icpc 2019 proceedings - avl2019+proceedings.pdf · 2019-05-22 · icpc 2019 may 22nd - 23rd, 2019 2...
TRANSCRIPT
1
ICPC 2019 May 22nd - 23rd, 2019
2
FOREWORD
Welcome to the 10th AVL International Commercial Powertrain Conference – ICPC, a platform to discuss common challenges and opportunities of truck, agricultural and construction equipment OEMs, organized by AVL in cooperation with SAE International.
The on-road and off-road industry is in rapid transition: to meet ever stringent environmental, legislative and economic targets, the current powertrain technology will no longer suffice.
The Keynote session, with the roadmap to drive the future and the implications on logistics, environment, and economics sets the scene for the conference.
Experts from the three powertrain industries will tell us what lies ahead in powertrain development, what can still be achieved with combustion engines
and transmissions to reduce CO2, and what is the potential of vehicle and machine electrification to achieve zero emissions.
Digitalization is the game changer, both on-road and off-road.
The closing round table discussion will try to find answers if the Commercial Powertrain Industry will continue with steady evolution or be threatened by disruption with severe implications on the companies’ success, job security and the economy.
We are once again looking forward to an exciting event, an opportunity to meet and network with many representatives of the leading companies of the three powertrain industries including their strong supplier base.
Dr. Marko Dekena
Executive Vice President
Off-road Business Unit
Prof. Dr. h.c. Helmut List
Chairman and CEO
DI Rolf Dreisbach
Executive Vice President
On-road Business Unit
CONTENT Page
3
ON-ROAD AND OFF-ROAD INDUSTRY IN TURMOIL?
1.1 Roadmap to drive the future - The powertrain diversification
8
Matthias Horx – Founder;
Zukunftsinstitut Horx GmbH
1.2 Technologies and Infrastructure needed for Sustainable Logistic 11
Prof. Dr. Helmut Zsifkovits - Professor of Industrial Logistics;
University of Leoben
1.3 What is needed to ensure efficient and clean road transport? 19
Dorothee Saar - Head of Transport and Air Quality;
Deutsche Umwelthilfe e.V
1.4 Economic Implications:
Impact of e-mobility on supply chain and related market expectation
22
Gerhard Stempfer - Manager Elektrification;
ZF Friedrichshafen AG
CONTENT Page
4
INNOVATIVE ICE AND EAS SOLUTIONS
2.1 Innovative EAS technologies in development
for on-road and off-road applications
26
Rolf Brück - Managing Director;
Continental Emitec GmbH
2.2 Lowest CO2 Emissions Despite Ultra-Low NOx 28
Gernot Graf - Head of Development & Calibration, Commercial Vehicle and Large Engine, Helmut Theißl, Klaus Hadl, Anton Arnberger;
AVL List GmbH
2.3 Development and testing of an innovative gas engine for heavy duty applications
36
Stefano Golini - Alternative Fuels Project Manager – Innovation Dept., David D’AMATO, Sergio GIORDANA, Paolo GROSSO, Diego IUDICE; FPT Industrial S.p.A.
Anton ARNBERGER, Gernot HASENBICHLER; AVL List GmbH
Davide PAREDI; Politecnico di Milano
Peter GRABNER; Technische Universität Graz
2.4 Potentials for friction reduction with commercial vehicle engines – Contribution of the power cell unit
56
Dr.-Ing. Andreas Pfeifer – Vice President Product Development Engine Systems;
Mahle GmbH
M.Sc. Tobias Funk, Dr.-Ing. Thomas Deuß, Dipl.-Ing. Holger Ehnis
MAHLE International GmbH
2.5 ICE optimized for off-road hybrid powertrain 63
Dr. - Ing. Markus Schwaderlapp - Senior Vice President Research & Development,
Dr.-Ing. Paul Grzeschik;
DEUTZ AG
CONTENT Page
5
VEHICLE AND MACHINE ELECTRIFICATION
3.1 Fuel Cells:
A Profitable Zero-Emission Solution for Heavy Duty Trucks
71
William Resende, Global Product Manager Fuel Cells,
Heimo Schreier, Dr. Alexander Schenk, Martin Ackerl;
AVL List GmbH
3.2 Commercial vehicle battery solutions 82
Krzysztof Paciura - Technical Project Lead (Power Electronics R&D/Project Manager);
Cummins Ltd.
3.3 The smart eCVT hybrid system for 2020+ Commercial vehicle application
87
Dr.Zhiqiang Lin - Executive Vice President;
Guangxi Yuchai Machinery Co., LTD
3.4 Tractor/implement systems – the next generation 92
Dr.-Ing. Joachim Sobotzik - Versatility Tractor Lead, Electric Drive Engineering Services;
John Deere European Technology Innovation Center Kaiserslautern, Germany
CONTENT Page
6
CONTRIBUTIONS TO REDUCE CO2 - ON-ROAD AND OFF-ROAD
4.1 The initiative of the AG machinery industry for CO2 emission reduction
96
Dr. Eberhard Nacke - Head of Product Strategy;
Claas KGaAmbH
4.2 Long haul truck powertrain control for low emission and fuel consumption in real traffic conditions
99
Alois Danninger – Manager Engine Controls;
AVL List GmbH
DIGITALIZATION - THE GAME CHANGER, ON-ROAD AND OFF-ROAD
5.1 Impacts of Digitalization on the Ag Industry 106
Dr. Markus Baldinger - Chief Technical Officer;
Pöttinger Landtechnik GmbH
5.2 ADAS and Autonomy for Trucks - A look into the future 109
Ozan Nalcıoğlu - Engineering Director, Alper Tekeli, Güvenç Barutçu, Berzah Ozan;
Ford Otomotiv AS
5.3 Digital Twins - Prerequisites and implications on
CE architectures and platforms
115
DI Dr. Thomas Fischinger – Digitalization Consultant
Wacker Neuson Beteiligungs Gmbh
CONTENT Page
7
COMMERCIAL POWERTRAIN INDUSTRY: EVOLUTION OR DISRUPTION?
6.1 Powertrain Trends and Developments in the Commercial Vehicle Industry
119
Dr. Carl Hergart - Director Powertrain and Advanced Engineering;
PACCAR Technical Center
6.2 Value Creation in the Commercial Powertrain Industry 128
Dr. Albert Neumann - Managing Director, Jana Mühlig, Xaver Müller;
Strategy Engineers
8
ICPC 2019 – 1.1
Roadmap to drive the future - The powertrain diversification
Matthias Horx
Zukunftsinstitut Horx GmbH
Copyright © 2019 AVL List GmbH, Zukunftsinstitut Horx GmbH and SAE International
ABSTRACT
When will the transportation business reach the next transformation stage, and what will be the factors and trends which lead to this point? There are three forces which shape the coming shift:
Energy and environmental:
The Anti-Global-Warming -Movement will become a powerful force in the next decade, and shape value systems and cultural behaviour. The goods transportation system will come under huge pressure. Electrification or hydrogen tech will come sooner then we think.
Technology and Infrastructure:
The steadily increasing transportation traffic creates tensions between different groups on the road. But automatic driving systems cannot change congestion, so we need more radical proposals such as:
"The Human Factor":
Lorry driving is a very mighty and deeply rooted male culture. At the same time lorry drivers are suffering under hard economic pressures. With the coming technological shifts, this will lead to conflicts around the steering wheel. Another driver culture with higher educational skills will emerge.
DAS TROLL-PRINZIP
Vor einiger Zeit reiste ich mit meiner Familie nach Island, in dieses aussergewöhnliche Land der Geysire, Vulkane und fantastischen Nordlichter. Dort wohnen, wie jeder weiss, die Trolle.
Trolle sind eigentlich harmlose, sogar nützliche Wesen. Sie hausen in Spalten im losen Lava-Geröll; dort, wo Moos und Steine kleine Höhlen und Gänge bilden. An den Strassenrändern sammeln sie leere Bierdosen, die die Isländer, gelegentlich wegwerfen,
wenn sie alkoholmässig über die Stränge schlagen (das kommt schon mal vor, wird allerdings immer weniger, seit die isländische Regierung strenge Gesundheitsprogramme ins Leben gerufen hat). Wenn sie genug gesammelt haben, geben die Trolle die Bierdosen beim nächsten Recyclinghof, auf isländisch endurvinssla stofnun ab. Deshalb sieht Island so unglaublich sauber aus, wie geleckt.
Trolle sind normalerweise sehr verspielt. Wenn man mit einem Geländewagen - wir waren zum Beispiel mit einem alten Landrover Defender, mindestens zwanzig Jahre alt, das Modell, das noch ganz ohne Federung auskam unterwegs - auf einer der endlosen Geröllstrassen durch die grandiose Landschaft fährt, schmeissen sie unablässig kleine Steine an die
Windschutzscheibe. Und kichern. Das hört man aber kaum, wegen des Fahrlärms.
Trolle können allerdings wachsen. Ziemlich schnell. Und je grösser sie werden, desto schlechter wird ihre Laune. Sie machen dann alles Mögliche kaputt. Zunächst noch aus Neugier, einfach mal so, um zu schauen, was passiert.
Irgendwann sind sie so gross wie eine Kuh. Oder ein riesiger Felsbrocken. Oder ein kleiner Berg. Und sie verhalten sich dann - wie sagt man so schön? -ungünstig. Wie ein Erdbeben, das man lieber nicht erleben möchte.
Weglaufen nutzt dann nichts mehr.
Natürlich glauben wir nicht an solche Geister-Geschichten. Das sind Märchen für Kinder, wie etwa die übelgelaunte Gr´yla, eine alte Frau die in der dunklen Zeit vor Weihnachten aus den kalten Bergen kommt und bis zu 10.000 auf einmal Kinder frisst. Jedes isländische Kind kennt sie. Oder die berühmten Elfen, wegen denen in Island auch schon mal eine Strasse umgeleitet wird. Island wimmelt von solchen Sagen. Wie kann es auch anders sein in
ICPC 2019 – 1.1
9
einer Landschaft, die bis zum Weltraum reicht und voller Wunder ist? Über weite Strecken besteht Island aus marsianischer Öde ( Im nördlichen Teil hat ESA Mars, die Mars-Expeditons-Vorbereitungs-Mission der europäischen Weltraumorganisation, ihre Kuppeln und Container aufgeschlagen). Wer in einer solchen Einöde lebt, MUSS sich mit Elfen und Trollen und bösartigen Hexen umgeben.
Das Erstaunliche ist nur, dass Trolle, obwohl sie nur Imagination sind, äusserst REAL sein können.
Trolle sind Saboteure auf unserem Weg in die Zukunft. Sie stehen sozusagen zwischen uns und dem Kommenden, das möglich ist.
Sie leben von einer menschlichen Grundenergie: Unserer Angst. Angst ist ihre Lieblingsspeise. Sie verzehren Angst zum Frühstück, zum Mittagessen und zu Abendessen, und gerne noch als kleine Happen zwischendurch. Angst ist das, was sie gross, stark und böse macht. Die Aufmerksamkeit, die Fixierung, die durch Angst entsteht, ist das, was sie zu gigantischer Form auflaufen lässt, bis sie den Himmel verdüstern.
Wir alle kennen diese Situation. Wir sitzen zusammen mit einer Gruppe von Freunden, die wir kennen und schätzen. Etwa in einem Gasthaus in den Bergen; jemand hat Geburtstag, man hat sich länger nicht gesehen, grosses Hallo zu Beginn. Man kommt ins Gespräch mit einem alten Bekannten, den man noch aus der Studentenzeit kennt, und mit dem man vor Jahrzehnten einmal auf einer turbulenten Reise in den Süden war, als man sich noch Hals über Kopf verlieben konnte.
Man sitzt und redet und trinkt ein bisschen Wein, nicht mehr so viel wie früher. Und nach einigen schönen Erinnerungen formuliert der gute alte Freund plötzlich Sätze wie:
„Ich glaube, es geht zu Ende. Das fliegt uns alles um die Ohren. Ich schätze, es geht noch zehn, zwanzig Jahre... aber dann... Meine Kinder beneide ich nicht.... “
Schweigen. Verlegenes Lachen. Man versucht zaghaft einige Gegenargumente. Lieber X, haben wir das nicht in unserer Jugend auch schon so gedacht, Du erinnerst Dich, Atomkrieg, Waldsterben, Kapitalismus, Tschernobyl? Aber der düstere Angst-Glanz in den Augen des alten Freundes hat eine spezifische Hartnäckigkeit. Ja sogar ein bestimmtes Glück.
Man kennt ihn ein bisschen. Man weiss: Es ist in Wahrheit eine Depression. Er hat, wie so viele der alten Rebellen, eine schwierige Kindheit gehabt.
Hässliche Dinge, die man nicht erzählen möchte. Aber was nutzt das, wenn man es weiss?
Oder man kennt seine Nachbarin seit vielen Jahren. Eine lebensatte Frau, eigentlich. Bis vor einigen Jahren immer fröhlich und positiv und ziemlich katholisch. Plötzlich verändert sie sie sich, wird langsamer, stummer, in sich gekehrter. Und dann kommt sie über den Gartenzaun mit allen möglichen konfusen Theorien - über geheime korrupter Politiker-Kreise und die Manipulation des Wetters, den Islam als grosse Verderben. Auf ihrem Gesicht ist plötzlich ein seltsame Genugtuung eingekehrt (Sie hat gerade eine ziemlich schlimme Scheidung von ihrem Mann, einem Rechtsanwalt, hinter sich).
Die Angst scheint eine geheimnisvolle innerliche Stärke zu verleihen.
Am irritierendsten sind diese inneren Troll-Anfälle, wenn sie sich bei Menschen bemerkbar machen, die die Zukunft geradezu für sich beanspruchen. Ich haben ein ums andere Mal erlebt, wie CEOS, Inhaber grosser Firmen, charismatische Männer, ihre innere Dunkelheit offenbarten. Bei einer festlichen Kundenveranstaltung, nach einer flammenden Motivationsrede zur gloriosen Zukunft ihrer Technik, ihres Unternehmens, sass ich beim Essen mit ihnen zusammen. Und hörte beim obligatorischen Filetsteak, das bei solchen Anlässen immer gereicht wird, plötzlich diese apokalyptische Geschichten.
Sie als Zukunftsforscher geben mit doch sicher recht, dass...
- Die Ressourcen zu Ende gehen (ausgerechnet die, mit dem die Firma des jeweiligen Konzerns ihr Geld verdient)...
- Der Mensch sich wie wahnsinnige Kaninchen vermehrt, das kann ja von den Ökosystemen her nicht gutgehen...
Der Euro demnächst auseinanderfliegt, diesmal aber ganz sicher...
Der Terrorismus unsere Gesellschaft zerstört.
Alle Liebe und Bindung, Anstand und Respekt zwischen den Menschen verschwindet.
Es gibt demnächst einen grossen Krieg, einen weltweiten Bürgerkrieg, bei dem die Armen die Reichen abschlachten. Vielleicht ist das ja sogar gerecht...
Wir werden von Algorithmen versklavt und in einem neuen Faschismus aufwachen, ohne dass wir es überhaupt merken....
ICPC 2019 – 1.1
10
Die letzte Variante wurde mir bei einem schweren Rothschild-Wein ausgerechnet vom Vorstand einer grossen IT-Firma aufgetischt. Mit einer Mischung aus Zynismus und eitler Selbstgeisselung ("Wenn Sie glauben, ich wüsste nicht, was wir tun, dann irren Sie sich!").
Das Bizarre an diesen Ängsten ist ihre seltsame Beliebigkeit ; meistens bewegt sich die Narration entlang von uralten Schauergeschichten, die schon seit eineigen Jahren völlig widerlegt sind (etwa die "Bevölkerungsexplosion" oder die "ständige Zunahme der Arbeitslosigkeit"; beliebt ist auch die "Vergreisung der Gesellschaft", die einfach nicht innovativ und digital genug ist, um es mit der Zukunft "aufzunehmen".). Geschichten, die irgendwo aus der Tiefe des medialen Bauches stammen, und unendlich weitergesponnen werden, wie im Märchen von Rapunzel das Haar. Nicht selten offenbart sich in der Art und Weise, wie die Untergangsgeschichten erzählt werden, direkt eine persönliche Niederlage, ein frisch vernähtes Trauma. Aber immer laufen sie auf dasselbe hinaus:
ES GIBT KEINE ZUKUNFT!
Wenn alle, oder die Mehrheit, das wirklich glaubt, dann ist der Moment gekommen, in dem der grosse, der ganz grosse Troll den Raum betritt, sich genüsslich am Hintern kratzt, um sich dann sich ächzend, stinkend und dennoch sehr gemütlich niederzulassen.
Es ist dann ziemlich schwer, ihn wieder zu vertreiben.
Das Internet hat dem Troll inzwischen eine neue Ikonographie verliehen. Das grinsende Clownsgesicht, das unentwegt ablacht - die Maske des Bösartigkeit und hämischen Besserwisserei, mit der jeder irgendwann konfrontiert wird, der in die Öffentlichkeit tritt. Gerade in dieser Figur des Internet-Trolls zeigt sich das Paradoxon der Angst: Der Seelengenuss, der von reiner Negativität auszugehen scheint.
Die Psychologie der Internet-Trolle ist inzwischen weitgehend erforscht. Es handelt sich zum grossen Teil um Menschen mit einem fatalen Selbstwirksamkeits-Problem. Der Mann (90 Prozent sind Männer), der in einem abgeschlossenen Raum vor einem Computer sitzt, und aus der komfortablen Distanz des elektronischen Raumes andere Menschen belästigt, beleidigt, verhöhnt, verunsichert, denunziert, verfolgt, nimmt eine Art Superposition ein. Er kann die Gefühle anderer in Richtung Angst manipulieren. Das gibt dem Ohnmächtigen eine ungeheure Wirksamkeitserfahrung. Eine Kontroll-Illusion. Das ist der Hebel seiner Wirksamkeit; es stabilisiert ihn in seiner eigenen Lebensangst.
Bei der Angst geht es immer auch um Macht. Oder kompensierte Ohnmacht.
Es ist leicht, sich von den elektronischen Hass- Trollen zu distanzieren. Das Pathologische ist offensichtlich. Aber es macht wenig Sinn, die Existenz der Trolle einfach zu negieren. Die Trolle sind seit Millionen von Jahren mit uns gewandert. Jetzt, im Zeitalter der elektronischen Verbindungen und Erregungen, werden sie endgültig aus ihrem Schlaf geweckt. Sie können, wie wir gesehen haben, sogar das Amt des amerikanischen Präsidenten bekleiden.
Die Erde zittert, das können wir spüren.
Es wird also Zeit für einen Showdown mit dem zu gross gewordenen Troll.
11
ICPC 2019 – 1.2
Technologies and Infrastructure needed for Sustainable Logistic
Prof. Dr. Helmut Zsifkovits
Montanuniversitaet Leoben
Copyright © 2019 AVL List GmbH, University of Leoben and SAE International
ABSTRACT
The way goods and physical objects are currently moved, handled, stored, distributed and supplied is not sustainable economically, environmentally, and socially. Several examples will be presented to illustrate the symptoms and effects of unsustainable logistics. Based on a Smart Logistics framework, approaches towards more sustainable transport, storage and provision of goods are discussed. Furthermore, a number of conceptual, technological and organizational models for Smart Logistics are identified, and potential applications will be outlined and discussed.
INTRODUCTION
Infrastructure comprises the entirety of sustainable facilities and supply channels to be used by private households and companies. Economic/technical infrastructure consists of transport infrastructure, information and communication infrastructure whereas social infrastructure includes institutions for education, healthcare, culture and security within a state and society [1].
A further distinction can be made between a macroeconomic view, as described above, and the microeconomic dimension defining the technical structural properties of a logistics system, such as means of transport and material handling, conveyors, warehouses, storage and picking technology, and the information and communication systems required for controlling these facilities.
Logistics infrastructure forms the backbone of logistics systems, including the transport infrastructure, and the suprastructure including logistics locations and real estate as well as the telecommunication infrastructure.
Consequently, infrastructure has a major impact on the key performance indicators of logistics and
production systems. These are measures of supply chain efficiency, like operating cost, lead time, flexibility and visibility, customer-focused indicators like service level and solution portfolio.
Furthermore, sustainability has become a critical factor in every logistics-related activity. The 2030 Agenda for Sustainable Development of the United Nations underlines a global commitment to “achieving sustainable development in its three dimensions - economic, social and environmental - in a balanced and integrated manner” [2]. In order to achieve sustainable development, i.e. “protect the planet from degradation, including through sustainable consumption and production, sustainably managing its natural resources and taking urgent action on climate change, so that it can support the needs of the present and future generations”, the merging of the three dimensions in the context of decisions at enterprise level and into the public policy cycle is required.
Transport is a major user of energy and burns most of the world's petroleum, therefore the environmental impact of transport infrastructure and operations is significant. Road transport is the largest contributor to global warming, creating air pollution, including nitrous oxides and particulates, and emission of carbon dioxide [3].
In 2015, the 2030 Agenda for Sustainable Development was adopted by all United Nations Member States, as a “shared blueprint for peace and prosperity for people and the planet, now and into the future”. The agenda defines 17 Sustainable Development Goals (SDGs), calling for joint action by all countries to end poverty and other deprivations, to improve health and education, reduce inequality, and spur economic growth. Also, climate change has to be tackled, and the preservation of the natural environment [4].
ICPC 2019 – 1.2
12
Resilient infrastructure is explicitly addressed in Goal 9 of SDG: “Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation.” [5]
Resilient infrastructure is interlinked with industrialization and innovation which are drivers of infrastructure development and economic growth. Thus, infrastructure is critical for achieving the socio-economic SDGs, inclusive growth (Goal 8), reducing poverty (Goal 1), eliminating hunger (Goal 2), ensuring good health and well-being (Goal 3), providing quality education (Goal 4), supplying clean water and sanitation (Goal 6).
Access to energy, clean water and sanitation is central for better education and for better health, and is also critical for gender equality as it increases mobility, output and productivity of women, in particular.
It has to be taken into account, though, that infrastructure, as defined by highways, airports, power plants and dams does affect, and is affected by the environment. The construction and operation of infrastructure accunts for approximately 70 percent of greenhouse gases (addressed in Goal 13). Linear infrastructure and dams have major impacts on terrestrial and aquatic ecosystems and biodiversity (Goals 14 and 15). In contrast, the increasingly visible effects of climate change, land degradation and deforestation pose major threats to infrastructure [5].
The United Nations Economic Commission for Europe (UNECE) was set up in 1947, with its major aim is to promote pan-European economic integration, as one of five regional commissions of the United Nations. UNECE goals with respect to infrastructure are to identify main Euro-Asian links for priority development and cooperation, ensure seamless connections throughout Europe through motorways and railways and facilitate border crossings.
Observatory – online repository for transport network information [6]
An online repository (Observatory, Figure 1) will be established to store and exchange basic information on identified transport networks. All international corridors will be hosted in a GIS environment [7].
This will be a major foundadtion for providing a comprehensive informational basis for future infrastructure planning of transport networks.
The way goods and physical objects are currently moved, handled, stored, distributed and supplied is
not sustainable economically, environmentally, and socially. The basic experience of transportation has not changed very much over the past 50 years. Whereas other industries have undergone revolutionary changes, transport infrastructure and vehicles (cars, trains, planes) still move at roughly the same speed as decades ago. The potential of technological advancements has been compensated by the increasing density of frequency of moving objects – and regulation. Several examples will be
ICPC 2019 – 1.2
13
presented to illustrate the symptoms and effects of unsustainable logistics.
• According to various surveys, between 20 and 40 percent of trucks run empty (without freight). In addition, there is a high percentage of partially loaded vehicles. The inefficient use of trucks leads to too many trucks on European roads, creates congestion and unnecessarily increases the direct and external costs (delays, damages, injuries, fatalities, emission) of vehicles.
• The average passenger car is in use 1 out of 24 hours. Some surveys even indicate, the vehicle is used only 36 minutes per day [8]. From this fact, an immense requirement for parking space arises.
• In Vienna, the area dedicated to cars is 12 million square kilometers; one fourth out of this is for parking cars. The ratio is similar in Berlin, London and other major European cities. In Berlin, on average, only about 60,000 cars are traveling at one time, while 1.2 million are parked.
There is a number of approaches and initiatives, though, that indicate progress in sustainable supply chains. More logistics services providers are taking sustainability and resource consumption into account when planning or purchasing transportation. A turn towards electric vehicles, and the usage of natural gas for ground fleets are developments to be mentioned. Cleaner trucks, trains, ships and planes are further factors, and the introduction of automation and cleaner technology in cargo handling and warehouse operations contribute to “greener” supply chains.
Packaging is becoming more sustainable, due to the usage of reusable and recycleable containers and materials, and the reduction of wasted space. It must not be neglected, though, that the use of boxes for E-Commerce is growing considerably faster than other market segments.
In order to eliminate or minimize wasteful resource usage before it is even introduced, sustainability in supply chains must be taken account of all the stages of planning and implementation, from product and process design to the sourcing of facilities, tools, materials, components, energy and packaging to the distribution of goods.
Digitization of supply chains can contribute to make them leaner, help eliminate or minimize waste and avoid obsolencence. Data analytics, the use of advanced algorithms and Artificial Intelligence provide tools to model and evaluate scenarios and
optimize operations, in terms of efficiency, flexibility and sustainability. Expected effects will be a more efficient use of shared resources, like storage space, vehicles, and production facilities, and a multi-echelon inventory optimization. This in turn enables more productive and economic operations, higher service levels, and more sustainable systems in their economic, environmental and social dimensions.
A SMART LOGISTICS FRAMEWORK
In this section, the authors develop the framework for smart and sustainable logistics, outline and discuss state of the art conceptualizations and combine their findings to a generic Smart Logistics Framework.
Kagermann et al. (2013) define Industry 4.0 as the technological-based integration of Cyber-Physical Systems (CPS) into production and logistics and the application of the Internet of Things (IoT) and services in industrial processes, including all the resulting consequences for the value chain, business models, services and labor organization. Production and logistics are considered as core areas of Industry 4.0 while business models and other corporate function will only play a minor role [9]. Smart Logistics is a core element of the Industry 4.0 concept.
Hermann et al. (2016) derived four basic formal principles from relevant publications for the implementation of Industry 4.0 approaches which are 1) the assurance of digital interconnectivity, 2) the decentralization of decision-making processes, 3) the availability of transparent information, and 4) the usage of technical assistance systems [10].
Bechtold et al. (2014) created a framework which comprises eight important value drivers based on the four pillars of Industry 4.0, namely, 1) Smart Solutions, 2) Smart Innovations, 3) Smart Supply Chains and 4) Smart Factory. In this model, products and services respectively innovation processes are conceptualized as independent elements. This framework should be used to ensure continuous growth and enhanced efficiency based on an organizational framework which includes an agile operating model, human resource management, change management, corporate governance, processes and digital infrastructure [11].
Based on the outlined models, the authors propose a new framework of Smart Logistics which is displayed in Figure 2. Thereby, Smart Logistics includes intelligent and smart supply chains, based on an agile cooperation in interlinked networks and the digital interconnectivity of organizations. The digital interconnectivity is assured by state-of-the-art information and communication technologies (ICT), data networks, sensors and actors, and intelligent
ICPC 2019 – 1.2
14
technologies for identification respectively tracking of materials, components and/or products. Autonomous transport vehicles in combination with automated warehouses as well as storage and handling
infrastructure enable the complete or at least partial self-control of internal and external material flow processes [12].
A smart and sustainable logistics framework (adapted from [12])
Smart Solutions are implemented through Smart Products and Smart Services. Smart Products based on Product-Enabled Information Devices (PEID), such as RFID, sensors, actors, allow the interoperability of systems by dynamically exchanging product data and additional in-depth information related to lifecycle management, products, and manufacturing processes. New product and process innovations may result from these. Fitting products with sensors can lead to improved information for the development of new features or materials, a better utilization and ongoing optimization of production and logistics systems through real-time condition monitoring.
Smart Innovations can be realized by developing cooperative innovation strategies and open innovation platforms which could be more effective in transforming company-internal innovation processes into dynamic processes within company networks.
In Smart Logistics, the implementation of sensors, actors, and Cyber-Physical Systems (CPS) increases the accuracy and real-time availability of information and lowers the costs of supply-chain-wide tracking and tracing systems [13]. Also, monitoring of
products without human participation is possible, to improve logistics processes, competitiveness and reinforce the confidence of consumers in the quality of the supply chain. Logistics systems efficiency can be increased by internally implementing real-time planning and control systems and externally synchronizing information by using cloud-based approaches or learning algorithms [14].
Automated guides vehicles (AGV) become more and more important for industrial enterprises, with the ability of reconfiguration, flexibility, and customizabilityMoreover, warehousing processes are supported by autonomous robots, intelligent carriers and advanced assistance systems for man-machine-interaction.
Smart Manufacturing uses data analytics to increase production efficiency by gaining deeper insights into the manufacturing processes, also to enhance planning accuracy and achieve cost reductions. Decision support systems can be used to allow a systematic evaluation among different scenarios in order to take better decisions. Moreover, Industry 4.0 strategies can be seen as enablers of automation by reducing the time from failure occurrence to failure
ICPC 2019 – 1.2
15
notification by automatically triggering fault-repair actions through Smart Devices. The material flow can be supported by digital assistance systems based on augmented reality, employees get individualized information about necessary tasks to get along in timed productions and decentralized working stations could negotiate cycle times and thus find the optimum between highest possible capacity utilization per working station and a continuous flow of goods [15].
TECHNOLOGY ENABLERS FOR SMART SUSTAINABLE SYSTEMS
In this section, the authors outline a set of technological concepts for Smart Logistics and discuss potential applications. Literature has developed a multitude of divergent frameworks, models and conceptualizations. Bechtold et al. (2014) identify the following technology concepts as the main enablers of Industry 4.0: 1) cloud computing, 2) mobile technologies, 3) robotics, 4) advanced analytics, 5) machine-to-machine-communication, 6) social media, and 7) 3D printing [11]. This classification can be regarded as unspecific because of a missing unambiguous classification of technologies as enablers for Smart Production and/or Smart Logistics initiatives. Subsequently, the authors describe the concepts of the Cyber-Physical Systems (CPS), the Internet of Things (IoT) and the Physical Internet (PI) as the core elements of the proposed Smart Logistics component within the Smart Logistics Framework.
Cyber-Physical Systems (CPS)
CPS are physical objects or structures, such as products, devices, buildings, means of transport, production facilities, logistics components, that include embedded systems in order to ensure interactive communication [16]. The systems are connected through local and global digital networks. CPS detect, analyze and capture their surrounding environment, using sensors data combined with available information and services. Moreover, actors are used to interact with physical objects. CPS act autonomously, decentrally, can build up network amongst themselves and can independently optimize themselves according to the principles of self-similar fractal production systems. The Smart Factory interacts with human resources and/or machines and is able to organize itself in a decentralized, real-time manner [16]. A virtual image of the reality (“Digital Twin”) is permanently analyzed and updated with real-time information, and continuously synchronized with information from the real environment.
Internet of Things (IoT)
The IoT as an essential part of CPS is commonly associated with Radio-Frequency Identification
(RFID) technologies. Thereby, the IoT is used to identify and track objects (e.g., products, container, machines, vehicles) in logistics systems and supply chains. The objects are constantly processing information about their surrounding environment and can be unambiguously allocated which increases the effectiveness and efficiency of all related monitoring and control processes [17].
Physical Internet (PI)
The PI is an open, standardized, worldwide freight transport system based on physical, digital and operative interconnectivity by using protocols, interfaces and modularization. A provider-free, industry-neutral and border-free standardization is one of the basic requirement for the PI which connects and virtualizes material flows, in analogy to the concept of the digital internet. Moreover, standardized containers and carriers are used to ensure a maximum utilization of transport vehicles and a better usage of spare capacities. These principles can be applied in internal logistics systems, as well as in transportation networks by using self-controlling, autonomous systems in transport and storage processes as one of the central elements of the PI. The usage of shared transport capacities, storage locations, hubs and delivery points will have a positive effect on both economic (e.g., short transportation times, lower costs of human resources) and ecological (e.g., reduction of traffic and emissions) effects [18].
APPROACHES TO A MORE SUSTAINABLE DESIGN
Solutions for sustainability [20]
In this section, possible ways to a sustainable development in its economic, social and environmental dimensions will be outlined. New tools and policy approaches will be required to design, assess and implement programs that meet the
ICPC 2019 – 1.2
16
defined goals. We must be aware that humans are not good at giving up luxury goods and services.
The anthropocentric, globalized culture of the past created dichotomic systems: artificial vs. natural,
mechanical vs. organic, empiric vs.noumenal. This had negative impacts on our relationships with nature [19]. The present trade off sustainability model with its associated infrastructure (coexisting social, technical and natural infrastructures) is not sufficient to solve or to correct our global problems (Figure 3).
Model of sustainability and associated infrastructures [19]
Sustainability requires innovation. More is needed, than just repair damages done to the natural environment. Figure 4 shows a model of maturity stages in the design of sustainable systems, processes and products.
In general, the following approaches can be applied to design for sustainability:
1. Reducing the consumption of resources: This can be applied at the level of individuals, with regard to one’s personal requirements, but also in the professional sectors of industry, retail and services, in product definition, in manufacturing systems, in transport networks and other systems.
2. Sharing objects: By jointly using resources, on a personal/private or enterprise level, utilization of devices, tools, machines, vehicles, or space can be improved, reducing the number or volume of total required resources.
The shift from ownership to service use, as a major element of sustainable use, has become available in private vehicle mobility. In order to make service use a new lifestyle, policy instruments have to focus it directly, rather than just changing marginal economic costs. Networks and procedures for pooling solutions have to be established.
3. Effectice control of flows: Advanced algorithms for scheduling and routing in combination with learning systems can significantly improve the performance and throughput of transport networks. Flow objects are goods, containers, verhicles or humans.
To name some examples and practices, autonous vehicles and car-sharing in combination will significantly change the picture and mode of city traffic.
Researchers at the Massachussets Institute of Technology (MIT) Senseable City Lab, the Swiss Institute of Technology (ETHZ), and the Italian National Research Council (CNR) have developed slot-based intersections that could replace traditional traffic lights, which in turn leads to a significant reduction of queues and delays. This model is based on a scenario where sensor-laden vehicles pass through intersections by communicating and remaining at a safe distance from each other, rather than grinding to a halt at traffic lights [21].
With car-sharing, the utilization of passenger cars would potentially increase from 2 to 80 percent, according to a survey by the Hungarian Academy of Sciences. Since the vehicles are always on the move, hardly any parking spaces would be required, A study by the University of Stuttgart found that 93 percent of the parking space could be saved [8].
ICPC 2019 – 1.2
17
CONCLUSION
As a finding from the theoretical and conceptual analyses, Smart Logistics will be able to contribute to an enhanced efficiency of supply chains and to sustainable growth of industrial enterprises based on new business models by taking advantage of the following potentials:
• Enhanced control of processes based on real-time information
• Dynamic and situationally-orientated design of processes in the sense of adaptive and self-controlling systems
• Utilization of synergies by sharing capacities on neutral and independent platforms
• Increased decision-making processes based on extensive data analyses (Data Analytics) in combination with closed loop learning systems
• Ability of a flexible and customized adaptation of products, services and processes
• Individualization of designs, configuration options, orders, planning procedures, production processes and ongoing operation under economic conditions
• Effective man and machine interaction by including new principles of work design and competence utilization
• Realizing new potentials for logistics management through the development of new business models and innovative services.
In general, based on the Industry 4.0 approaches, Smart Logistics can be identified as a crucial element of digitalization in the industrial value chain. Smart Logistics is based on the usage of agile cooperation networks and on the information- respectively organization-based connectivity in order to enable intelligent and lean supply chains.
CPS, the IoT and the PI can be seen as integral concepts of Smart Logistics, aiming at an increased supply chain efficiency by the creation of (partly) autonomous systems and processes. Independent platforms for logistics services (e.g., transportation, storage, packaging, control of material and information flow) contribute to a better usage of resources and to the creation of new business models. Advanced data analytics provides tools for more efficient decision-making processes.
The consistent traceability of material flows which is based on new methods of automated identification and tracking, the development of self-controlled autonomous systems for transport and storage and the increase usage of advanced data analytics can be regarded as the first steps on the path to Smart Logistics.
In this context, the following future challenges are identified: The establishment of the provider-free, industry-neutral and border-free standardization of systems and interfaces in material- and information-flow processes, the definition of business cases in order to evaluate the benefits of investments in new technologies, the development of innovative organizational models for the integration of new technologies, the assurance of the security for human resources and data (Cyber Security), the further development and promotion of digitalization competences in vocational education and training incentives and the continuing integration of emerging technologies (e.g., Artificial intelligence (AI), Machine Learning, etc.) into logistics processes.
REFERENCES
[1] Gleissner, H., Femerling, J. Ch. 2013. Logistical Infrastructure, in: Logistics - Basics - Exercises - Case Studies, Springer 2013
[2] United Nations 2015. Integrating the three dimensions of sustainable development: A framework and toolsUnited Nations publication, ST/ESCAP/2737
[3] Fuglestvet, J., Berntsen, T., Myhre, G., Rypdal, K., and Skeie, R.B. 2007. Climate forcing from the transport sectors, Center for International Climate and Environmental Research, https://www.pnas.org/content/pnas/105/2/454.full.pdf [accessed 08 May 2019]
[4] Division for Sustainable Development Goals (DSDG) in the United Nations Department of Economic and Social Affairs (UNDESA) 2015. Sustainable Development Goals, https://sustainabledevelopment.un.org/?menu=1300 [accessed 08 May 2019]
[5] United Nations Environment Management Group (EMG) 2019. Sustainable Infrastructure for the SDGs, https://unemg.org/sustainable-infrastructure-for-the-sdgs/ [accessed 08 May 2019]
[6] Blackburn, A. 2017. SDG 9: Relevant UNECE Work on Resilient Infrastructure. http://www.unece.org/fileadmin/DAM/trans/main/SDGs/Workshop_1_-_October_2017/II_-_Relevant_UNECE_Work_on_Resilient_Infrastructure_-_SDG_9__UNECE_.pdf [accessed 10 May 2019]
ICPC 2019 – 1.2
18
[7] United Nations Economic Commission for Europe (UNECE) 2019. Transport and the Sustainable Development Goals, http://www.unece.org/trans/transport-and-the-sustainable-development-goals.html [accessed 10 May 2019]
[8] Pumhösel A. 2017. Weniger Autos in der Stadt der Zukunft. In: Der Standard, 21. Juli 2017, https://derstandard.at/2000061580102/Weniger-Autos-in-der-Stadt-der-Zukunft [accessed 10 May 2019]
[9] Kagermann, H., Helbig, J., Hellinger, A., Wahlster, W. 2013: Deutschlands Zukunft als Produktionsstandort sichern: Umsetzungsem-pfehlungen für das Zukunftsprojekt Industrie 4.0. Abschlussbericht des Arbeitskreises Industrie 4.0. acatech – Deutsche Akademie der Technikwissenschaften e.V., https://www.bmbf.de/files/Umsetzungsempfehlungen_Industrie4_0.pdf [accessed 15 January 2015]
[10] Hermann, M., Pentek, T., Otto, B. 2016. Design Principles for Industrie 4.0 Scenarios. In: Bui, T.X., Sprague, R.H., (eds). Proceedings of the 49th Annual Hawaii International Conference on System Sciences: 5-8 January 2016, Kauai, Hawaii. 2016 49th Hawaii International Conference on System Sciences (HICSS); 5/1/2016 - 8/1/2016; Koloa, HI, USA. Piscataway, NJ: IEEE. p. 3928–3937.
[11] Bechtold, J., Lauenstein, C., Kern, A., Bernhofer, L. 2014. Industrie 4.0 - Eine Einschätzung von Capgemini Consulting: Der Blick über den Hype hinaus. Capgemini Consulting, accessed 2019 Jan 15. https://www.capgemini.com/de-de/wp-content/uploads/sites/5/2017/07/industrie-4.0-de.pdf.
[12] Zsifkovits, H., Woschank, M. 2019. Smart Logistics – Technologiekonzepte und Potentiale. Berg- und Huettenmaennische Monatshefte. 615. doi:10.1007/s00501-018-0806-9.
[13] Louw, L., Walker, M. 2018. Design and implementation of a low cost RFID track and trace system in a learning factory. Procedia Manufacturing. 23:255–260. doi:10.1016/ j.promfg.2018.04.026.
[14] Qu, T., Lei, S.P., Wang, Z.Z., Nie, D.X., Chen, X., Huang, G.Q. 2016. IoT-based real-time production logistics synchronization system under smart cloud manufacturing. The International Journal of Advanced Manufacturing Technology. 84(1-4):147–164. doi:10.1007/s00170-015-7220-1.
[15] Kolberg, D., Zuehlke, D. 2015. Lean Automation enabled by Industry 4.0 Technologies. IFAC-PapersOnLine. 48(3):1870–1875. doi:10.1016/j.ifacol.2015.06.359.
[16] Bauernhansl, T., ten Hompel, M., Vogel-Heuser, B. 2014 (eds). Industrie 4.0 in Produktion, Automatisierung und Logistik: Anwendung, Technologien, Migration. Springer, Wiesbaden.
[17] Boyes, H., Hallaq, B., Cunningham, J., Watson, T. 2018. The industrial internet of things (IIoT): An analysis framework. Computers in Industry. 101:1–12. doi:10.1016/j.compind.2018.04.015.
[18] Montreuil, B. 2011. Toward a Physical Internet: meeting the global logistics sustainability grand challenge. Logistics Research. 3(2-3):71–87. doi:10.1007/s12159-011-0045-x.
[19] Swiatek, L. 2019. From Industry 4.0 to Nature 4.0 – Sustainable Infrastructure Evolution by Design, in: Jerzy Charytonowicz, Christianne Falcão Editors,Advances in Human Factors, Sustainable Urban Planning and Infrastructure, Proceedings of the AHFE 2018 International Conference on Human Factors, Sustainable Urban Planning and Infrastructure, July 21–25, 2018, Loews Sapphire Falls Resort at Universal Studios, Orlando, Florida, USA
[20] Tischer, U., Charter, M. 2001. Sustainable Product Design, in: Sustainable Solutions, Sheffield: Greenleaf
[21] Tachet, R., Santi, P., Sobolevsky, S., Reyes-Castro, L., Frazzoli, E., Helbing, D., and Ratti, C. 2016. Revisiting Street Intersections using Slot-Based Systems. PloS ONE, 2016http://dx.doi.org/10.1371/journal.pone.0149607
19
ICPC 2019 – 1.3
What is needed to ensure efficient and clean road transport?
Dorothee Saar
Deutsche Umwelthilfe e.V.
Copyright © 2019 AVL List GmbH, Deutsche Umwelthilfe e.V. and SAE International
ABSTRACT
Air quality and climate targets require additional efforts to reduce emission from road transport. Compliance with existing standards and the definition of standards for future technologies are necessary. Changes in technology – driven by stricter legal requirements and requirements from customer side – can be a chance for the sector with regard to competiveness on the global market. But also for new technologies, clear targets and standards are needed. Different interests have to be considered - individual mobility, the economic importance of the sector and urgent climate policy requirements. NGOs like Deutsche Umwelthilfe (DUH) stimulate a broad public debate on real world emission from the sector and demand compliance with existing legislation. For new technologies, standards and effective market surveillance have to be introduced. The current debate on a transition of transport also includes aspects like the future role of public transport as well as social aspects both from consumers and from employees side.
INTRODUCTION
In Europe, about 80,000 premature deaths are contributable to high NO2 concentration [EEA 2018]. High NO2 concentration in urban areas mainly derive from (diesel-fueled) road transport. About 45% of traffic based monitoring stations show exceedance of NO2 concentration limit values in Germany in 2017 (similar in France, Italy, UK) [UBA 2019].
The commitments under the Paris agreement and several national and EU agreements require CO2 redution in the transport sector by around 40% until 2030. However, in Germany, CO2 emission from road transport are as high as in 1990 [UBA 2019]. Beside the increase of vehicles and motorization, the growing gap between official CO2 numbers and real world consumption is responsible for that.
The necessary switch to renewable fuels however requires significant decrease in energy consumption.
Role of DUH
Deutsche Umwelthilfe (DUH) is an independent NGO for environmental and consumer right protection founded in 1975. We are engaged for better nature protection, transition towards renewable energy, better air quality and sustainable transport modes in order to ensure a healthy environment for us and for future generations. For many years, we are engaged for low emission and energy efficient transportation. Due to ongoing breach of binding EU air quality values in many German cities, we currently run 35 cases to achieve effective air quality plans. We also have been very active to elucidate the diesel scandal. In this context we also provide own on-road-emission tests of more than 100 passenger cars [1] that also include measurements of NOx-emission before and after mandatory software updates from various models. The result is disappointing, showing that under cold ambient temperature emission might be even higher than before. However, we also saw Euro 6d temp vehicles performing with NO2 emission values way below the limit value (Figure 1).
Figure 1 Euro 6d temp vehicle with low NO2 emission values (source: DUH)
In the context of the diesel scandal, we started legal cases against authorities to get access to relevant information. This approach takes a very long breath
ICPC 2019 – 1.3
20
and both authorities and industry obviously have no interest in transparency. Our latest success is a final decision against the Ministry of Transport to give insight in the protocols of the so called “Inquiry committee Volkswagen” set up by the ministry. In the course of the inquiry, the ministry commissioned emission tests on various vehicles. However, the data has only partly been published. We expect to get full insight within this year.
As a result of our legal cases for better air quality, bans for specific diesel vehicles are discussed in a lot of German cities and are to implemented in some of them – among them Stuttgart, the home of Daimler, Porsche and Bosch. The administrative court just announced recently that a ban for Euro 5 diesel has to be integrated in the local air quality plan by July 2019.
However, taking legal action is only one part of our work and we continue to seek the dialogue with all relevant stakeholders and the public. Fortunately, the diesel technology is not decisive for the compliance with our climate goals. DUH has gathered some arguments to damask this persistent myth [2]
WHAT IS NEEDED TO COMPLY WITH THE COMMITMENTS?
European legislation on emission standards is complex and rather ambitious. However, it lags implementation, independent control and sanctioning which leads to emission of exhaust gases above the current limit values.
Market surveillance and transparency
The diesel scandal brought facts to light that were known to experts long before. Three and a half year later, the problems still have not been solved. Despite several requests based on freedom of information legislation, there is no disclosure of the assessment of defeat devices, requirements and effects of software updates – mandatory or voluntary. Consumers still wait for adequate compensation and unrepaired vehicles move to Eastern European countries, downgrading air quality on site.
The increase of regulatory details as well as complex technology and software features challenge market surveillance. A clear commitment to compliance with standards under “normal use” is thus what we call for. The basis for this requirement is set out in the EU 715/2007 regulation. Independent third parties need to be involved – at least until authorities and manufacturers provide their findings.
Better market surveillance also means better periodical technical inspection. The current procedure
does not detect malfunctioning exhaust cleaning systems reliably and must thus be amended by emission tests for NOx under load and a proper system to measure particle number PN for both diesel and gasoline. DUH together with manufacturers of measurement devices just recently presented convenient technology and a proposal for a test procedure [3]
RDE for CO2
Better control of real world emission is also necessary for real world CO2-emission. CO2 emissions are currently measured under lab conditions only. According to the independent ICCT, the gap between certification data and real world fuel consumption has grown from 8% in average in 2001 to 39% in 2017 under unchanged test conditions [ICCT 2018].
The new test procedure WLTP offers some improvement towards more realistic conditions. However, it still does not fully reflect driving on the road and circumvention can still not be excluded. A high WLTP as “starting point” for the next phase of CO2 regulation for passenger cars as of 2021 would weaken the effect of further CO2 mitigation since a percental reduction is required and not a concrete value. Latest publication from Emission Analytics [EA 2019] raises questions and support the demand of onroad emission testing in the certification procedure. We call for a methodology how to measure CO2 emission on the road. First proposals are available. Obviously, the procedure must be reproducible and test conditions clearly defined. Independent third parties proofing their competence should be included as well.
Efficiency standards are necessary for vehicles driven by renewable fuels as well. The fact that BEVs are counted as “zero” with regard to their CO2 emission and the current practice to assess plug-in-hybrids disguise the real world emission from those vehicles instead of incentivizing efficient models which are necessary to lower the total energy consumption in the sector. How should such standards look like? Should they rather focus on the vehicle or on the battery? Should they also include strategies for recycling and second life? The debate is open!
Only Technology?
There is probably high technological potential for further decrease of emission. However, this has to stimulated by clear requirements and controlled. Existing legislation to lower CO2 emission from passenger cars and trucks will contribute to the overall goal – namely if we do not manage to close the gap between real world emission and official numbers.
ICPC 2019 – 1.3
21
The ideas are not new. However, they are not implemented yet. Numerous studies recommend a change in taxation of fuels and vehicles that stimulate low emission vehicles and reflect the real costs of burning fossil fuels. There are numerous good examples in Europe that show how targeted taxation helps to lower average CO2 emission in the passenger car fleet over the years [FÖS 2018]. Pricing CO2 even in the non-ETS sector transport needs to be tailored and has to take the specific willingness to pay into account. A pricing will amend but not replace binding reduction targets. German government announced a climate law in 2019 to define concrete steps that fulfil the 2030 target. A good window though to come up with concrete solutions that not only will become effective in the far future.
In addition, the way must be paved to push sustainable transport modes that will also lead to a decrease in number of vehicles. More engagement is needed to promote and facilitate public transport and also improve conditions for safe cycling and walking in urban areas. The connected transition in the sector needs to be discussed with the relevant stakeholders.
CONCLUSION
European legislation alone does not ensure the transition needed in the transport sector but needs implementation and effective market surveillance. Subsidies on national level need to support sustainable technology and transport modes rather high emitting and oversized vehicles. A comprehensive legal and political frame is needed to stimulate a transition towards new transport modes and technologies that provides both short term and mid term decrease of harmful emission. This has to be supplemented by public debate about the future of mobility. Latest sales numbers might only mean a spot light. However, they see non-European car makers with e-vehicles on the top of the sales lists.
Clear guidelines and ambitious targets are also relevant to define the future role of this industry sector and its role in the global context.
LITERATURE
• Agora Verkehrswende 2019: Blog: Warum wir Regeln für die Effizienz von Elektrofahrzeugen brauchen
• Emission Analytics 2019: The WLTP enigma
• European Environment Agency 2019: Air quality report 2018
• Forum Ökologische Marktwirtschaft FÖS 2018: Fair and low carbon vehicle taxation in Europe. A report for Transport & Environment
• ICCT: From laboratory to road: A 2018 update of official and "real-world" fuel consumption and CO2 values for passenger cars in Europe
• Sachverständigenrat für Umweltfragen SRU 2017: Umsteuern erforderlich: Klimaschutz im Verkehrssektor. Sondergutachten 2017
• Umweltbundesamt UBA 2019: Pressemitteilung vom 02.04.2019
• Umweltbundesamt: Handbuch Emissionsfaktoren des Straßenverkehrs, Version 3.3
REFERENCES
[1] (https://www.duh.de/projekte/eki-kontrollen/eki-ergebnisse/)
[2] https://www.duh.de/fileadmin/user_upload/download/Projektinformation/Verkehr/CO2-Minderung/Infopapier_Diesel_Klimaschutz_M%C3%A4rz2018.pdf
[3] https://www.duh.de/presse/pressemitteilungen/pressemitteilung/weiterentwicklung-der-periodischen-abgasuntersuchung-dringend-erforderlich-deutsche-umwelthilfe-ste/
22
ICPC 2019 – 1.4
Economic Implications: Impact of e-mobility on supply chain
and related market expectation
Gerhard Stempfer
ZF Friedrichshafen AG
Copyright © 2019 AVL List GmbH, ZF Friedrichshafen AG and SAE International
ABSTRACT
ZF is a global technology company and supplies systems for passenger cars, commercial vehicles, and industrial technology, enabling the next generation of mobility. With its comprehensive technology portfolio, the company offers integrated solutions for established vehicle manufacturers, mobility providers, and start-up companies in the fields of transportation and mobility. ZF continually enhances its systems in the areas of digital connectivity and automation in order to allow vehicles to see, think, and act.
In all of these applications, market and legislation requirements have shifted to emission reduction or even locally defined Zero Emission standards according to application-specific speeds and steps. Electrification-related technologies improve significantly in parallel, and each respectively approaches “market availability” status.
Considering these changes, ZF prepared and is currently implementing the Next Generation Mobility strategy, in which electric mobility solutions are a key element for all aforementioned applications with a special focus on electromechanic drive and steering systems.
The expectations of industry partners on this new drive and steering system is fostered by the speed of market demand: Be fast in bringing out application-specific system solutions without requirement specifications, but with system integration, competence, and affordable costs.
In addition to customer expectations, ZF’s strategy demands the following additional key competencies:
- System integration in HEV and EV
- Symbiosis of e-motor with transmission/axle
- Development of e-motors and inverters
- Management of e-motor, inverter blocksets
- Setup of modular software for HEV and EV
How can these requirements and expectations be served at the necessary speed and within a wide spectrum of application-specific solutions?
Focusing on these targets, ZF decided to set up a new E-Mobility Project House that is characterized by:
- Serving truck-, bus-, off-highway-, and marine-related applications directly from one source with eMobility system solutions
- Working in explore mode and serving customer demand with Minimum Viable Products (MVPs), in partnership-based pilot projects at maximum speed
- Enabling application-specific system solutions
- Integrating all ZF competencies in e-motor and inverter development and managing the e-mobility solution blockset
- Integrating internal and external industrialization facilities and partners to prepare necessary global production capabilities
With this Electric Mobility Project House, established requirements and customer expectations will be satisfied.
Strengthened by this approach, ZF can support industry customers in implementing Next Generation Mobility and answer future societal demand with affordable emission-free or emission-reduced vehicles.
ICPC 2019 – 1.4
23
CHANGE OF REQUIREMENTS
In both society and industry-related applications relevant to ZF, requirements and market expectations change quickly.
Major changes include:
• Increase of population
• Urbanization
• Local emission reduction
• Decarbonization
• Digitalization An increase in population causes an increase in resource and energy demands as well as emission levels. According to a number of estimates, two thirds of the world population will live in metropolises in 2050. Together, these two changes cause significant growth in urban areas and increase pressure to reduce local emissions in metropolises.
We see global examples of low to ultralow emission zones and intense discussion of zero emission zones.
Discussion about climate change is still controversial. Scientists agree that the primary root cause of global warming is CO2 emissions caused by humans, methane, and other gases. Apart from differing opinions, decarbonization plans are underway in certain industries and regions.
As part of the industry, we need to develop technologies that satisfy CO2 reduction plans. We expect further reduction to lower values in additional applications, compared to passenger cars and trucks.
The influences of digitalization lead in different directions. On the one hand, e-commerce causes increasing goods transportation and will enable automated and autonomous vehicles to change complete vehicle architectures.
All in all, we expect these requirement changes to result in disruptive technology changes in the vehicle industry, including in electric drives, electric steering systems, and ePTOs.
MARKET EXPECTATIONS RELATED TO E-MOBILITY
The first aspect of e-mobility market expectation is diversity related to markets, timing, applications, and solutions. This means that in each application, region or country the market introduction and penetration scenario is different.
To handle this diversity, ZF works with scenarios in different markets and applications. For example, in passenger car applications, expectations are almost equal between conventional and electrified vehicles.
For truck applications, the expected scenario is globally more diverse and the electrification quote is significantly lower with later timing compared to passenger car applications, especially in the HD segment.
The expected scenario for city buses is also globally very diverse, but increasing faster, whereas coaches more closely follow the truck evolution.
Industrial applications are again significantly more diverse with different scenarios. In marine technology, electric mobility will be more visible in pleasure craft than commercial fast craft. There is high diversity in MD- and MD-material handling and special solutions for agricultural engineering, and again, very high diversity in construction equipment.
As an example, if we compare the expected scenario of e-mobility evolution construction equipment with truck applications, we again see significantly lower values and later timing.
Besides differences, it is also important to discuss common aspects within commercial vehicle and industrial applications:
a) Commonalities in performance and life cycle:
In addition to lower and, at least from the point of view of magnitude, comparable values in terms of power and torque requirements, product life cycles are comparable between commercial vehicles and industrial applications.
b) Commonalities in e-mobility introduction:
In nearly all commercial vehicle and industrial applications, we expect market preparation or introduction of e-mobility solutions.
c) Main market expectations:
Based on these diverse e-mobility market preparation or introduction scenarios, the following expectations are of high importance:
• Providing e-mobility solutions starting at low and unpredictable volumes
• Solutions enable same or increased performance level
• High durability from first product generation
• Very fast progress from first concept to SOP
• System integration support necessary
• Comparable low prototype costs
• Despite above expectations: attractive series costs and outlook
ICPC 2019 – 1.4
24
According to market expectations, an investment in new technology and solutions that is based on low and unpredictable volumes in parallel with attraction series costs is necessary.
In the following sections, we will discuss the related ZF vision and selected strategic steps to satisfy these market expectations.
NEXT GENERATION MOBILITY AND RELATED STRATEGIC STEPS
Next Generation Mobility:
Based on this requirement change and related market expectations, ZF prepared and rolled out its vision called Next Generation Mobility, starting with the mission to offer clean and Zero Emission solutions.
This vision also applies to commercial vehicles and industrial applications, and is currently being implemented for these applications.
The electric mobility technology area states that for all mentioned vehicle applications, ZF is developing and will develop and provide electric mobility system solutions, including related components and technologies. In addition to technology solutions, system integration is provided by ZF to implement these solutions within the expected time line.
ZF will provide these solutions for the global market depending on demand and the focus of each region. Additionally, we expect these new technologies and new market requirements to create new vehicle concepts, especially by combining automated driving and e-mobility.
Related ZF Strategic Steps:
In order to implement this mission, many measures and strategic steps are necessary, some of which have already been implemented and others planned. In the following section, we will discuss some selected strategic steps and their status within ZF:
a) IMS electric drives and ZF e-mobility portfolio
b) Strategic partnerships
c) Integration of electric motor and inverter competence
d) IMS electric drives and system integration
e) Speed and MVP
f) Electric Mobility Project House between commercial vehicles and industrial technology
g) Building blockset for electric motor and inverter
In 2017 and 2018, there was a program called IMS designed to develop a new electric mobility portfolio for industrial applications. The following product positioning is the result of this program for ZF:
- Electromechanic Steering Systems
- Electromechanic Drivetrain Systems
- ePTO Systems
These types of electromechanic systems, including first pilot products, are and will be offered by ZF in the new portfolio, including e-motors, inverters, and related controls.
In order to be very fast in providing electromechanic systems to the market, a strategic corporation was set up with ZAPI Group. Thanks to combined forces and components, this corporation enabled early and very important common electromechanic systems, which are already available on the market or being prepared for market launch within the next years.
For the development teams at ZF in both commercial vehicle and industrial applications, e-motor and inverter development as well as industrialization competence and capacity was built up around two pillars:
a) Integrating technology experienced resources based within passenger car eMobility development
b) Building up competence in specific product line teams
Additionally, within the program for IMS system integration, competence and capacity for hybrid and electric vehicles was established and implemented in the first pilot projects.
As electric mobility market expectations are very dynamic, the time to market is shorter compared to established technologies. In order to satisfy this expectation, ZF decided to work in different project steering and operation modes, enabling shorter time to market with more agility.
One measure to facilitate this in the best way possible was the setting up of a new organizational unit, Electric Mobility Project House, at the beginning of 2019. Here, electric mobility projects for commercial vehicle and industrial applications will be implemented to produce the best possible framework conditions to leverage synergies.
ICPC 2019 – 1.4
25
Within this project house, a commonly used building blockset for the electric motor and inverter will be developed and managed, enabling integration of common components in different commercial vehicle and industrial applications.
SUMMARY OF IMPACT OF E-MOBILITY ON SUPPLY CHAIN
Based on these changes, expectations, and project experience, the following summary regarding impact on supply chain and on ZF can be provided:
Electric mobility solutions will be introduced for nearly all relevant applications; timing and market penetration scenarios are very diverse.
a) New portfolio and positioning is necessary.
b) Investment in new products is necessary. The challenge is the right balance between current and new products.
c) A shift of capacity is necessary, including the buildup of new competencies in e-motor and inverter development.
d) System integration and cooperation are important.
e) Very fast market launch is expected; higher speed compared to established markets.
f) Attractive costs are a key element for the product and business case as well as acceptance of electric mobility.
In preparation for this cost level, ZF decided to modify the organization and set up the Electric Mobility Project House between CV und industrial applications in order to leverage synergies more comprehensively:
- In general regarding e-mobility technology with all electric mobility applications
- Within CV and industrial applications regarding systems and components
- Within electromechanic systems regarding transmissions and axles
CONCLUSION
Currently ongoing requirement changes will intensely influence vehicle technologies and solutions in all applications. Even if global market penetration needs time for all applications, the impact on the supply chain is already a reality.
This means that the supply chain is currently reinventing itself for new e-mobility solutions and adapting to it in terms of organization.
ZF considers electric mobility in its Next Generation Mobility vision as a key technology and is preparing future solutions and the necessary organization very carefully and with a high degree of importance.
26
ICPC 2019 – 2.1
Innovative EAS technologies in development for on-road and off-road applications
Rolf Brück
Continental Emitec GmbH
Copyright © 2019 AVL List GmbH, Continental Emitec GmbH and SAE International
ABSTRACT
Similar to passenger cars also for on-road and off-road heavy-duty vehicles the challenge on the emission legislation side is comparable. The current discussion on tightening of NOX-limits in the commercial vehicle sector in Europe as well as especially in the Unites States presents a new challenge for the engine- and catalyst-manufacturer. Lowering of 90 % compared to todays limits (down to 0,02 g/bhp-hr) requires NOX-reduction at all engine operating conditions. Especially cold start and load points with low exhaust temperatures demand high activity of the exhaust aftertreatment system, particularly the amount and preparation of the reductant.
In passenger car application well proven close coupled catalyst configuration is deemed to be a major step to reach the future limits. The use of additional heating measures seems unavoidable to ensure the perfect preparation of the reductant on the one hand side and to reach the needed conversion efficiency of the SCR catalysts on the other hand.
The introduction of close-coupled catalyst solutions for heavy-duty applications requests new solutions on the substrate and catalyst side, as well as on the canning side.
SUMMARY
The estimated tightening of NOX-limits in the commercial vehicle – without any negative impact on greenhouse gas (CO2) emissions – requires NOX reductions under all operating conditions. Cold start and load points with low exhaust gas temperatures place increased requirements on the activity of the exhaust gas aftertreatment system and, in particular here, on the quantity and conditioning of the reducing agent.
Reducing raw NOX-emissions by adjusting the performance map and/or implementing engine heating measures are difficult because of the associated increase in CO2 emissions. Typical exhaust gas aftertreatment systems for commercial vehicles comprise the following:
Diesel oxidation catalyst (DOC):
Here, engine HC and CO emissions are oxidized and, if necessary, any additional fuel is used for increasing the temperature in the exhaust system. Nitrogen oxide in the engine is converted to NO2 and used for “passive” DPF regeneration.
Diesel particulate filter (DPF):
This system filters out the particulates. Regeneration takes place either passively with NO2 (formed via the DOC) or through an active increase in temperature via the additional injection of fuel. Particulate filters often have an oxidation coating comparable to that in DOCs.
Reducing agent dosage (watery urea solution: AdBlue®, DEF):
Provision of ammonia for reducing nitrogen oxide levels in the downstream SCR catalyst.
Nitrogen oxide reduction (SCR):
Selective reduction of the nitrogen oxide takes place with the ammonia (NH3) formed from the watery urea solution. The potential breakthrough of excessive ammonia is prevented by the ammonia slip catalyst.
Today in most Heavy Duty Exhaust systems these components are located in the muffler mounted either at the frame of Heavy Duty vehicles or in underfloor positions for medium duty vehicle.
For heavy duty catalyst systems the total catalyst and filter volume can go up to about 80l, compared to about 4,5l for a passenger car exhaust system. This
ICPC 2019 – 2.1
27
demonstrates the huge amount of energy needed to heat-up a truck catalyst system.
With the more stringent emission legislation, the cold start portion of the tailpipe emissions becomes of major importance. Also the temperature level at low load during city driving is getting a challenge, because similar to passenger cars, RDE or In-Use tests also in city driving will become the future.
By that the thermal management of the catalyst system becomes of major importance.
Beside moving at least a part of the catalyst into a close coupled position, active heating measures will be needed.
Todays truck engine compartments / frame designs do not allow to put the complete catalyst system close coupled. But moving the DOC and the SCR injection to a close coupled position seems possible in most applications in a first step. A vertical mounted rectangular metal substrate between engine and frame is an innovative solution. Also the so called “Universal Decomposition Pipe” supports a close couples DEF injection with a 100% evaporation of the droplets. By that flex bellows behind the close-coupled system are not negatively influenced by deposits.
Regarding active heating measures particularly an electrical heated catalyst, which is already known from passenger car and bus retrofit can be used. In combination with a HC-Doser the electrically heated catalyst works as a “match head”. A heating power of 10-15kW can be achieved.
It could be demonstrated that the combination of close couples catalyst, electrically heated catalyst and HC-dosing in front, is a high efficient solution to heat-up the catalyst system of heavy duty trucks and reduce the emissions significantly.
28
ICPC 2019 – 2.2
Lowest CO2 Emissions Despite Ultra-Low NOx
Gernot Graf, Helmut Theißl, Klaus Hadl, Anton Arnberger
AVL List GmbH
Copyright © 2019 AVL List GmbH and SAE International
ABSTRACT
Upcoming ultra-low NOx emission legislations in the USA and Europe require the fulfillment of lowest emission limits. Therefore, a highly efficient exhaust aftertreatment system in combination with a suitable control architecture, low NOx engine out emissions and rapid heat-up measures become mandatory. Using a 2-stage SCR system not only allows high DeNOx-conversion immediately after cold start but also gives additional benefits in terms of passive regeneration, PN filtration efficiency, DeNOx balancing and diagnostic strategy. In order to ensure a rapid heat-up and keep warm of the exhaust aftertreatment system, a variable valve train is an attractive option for future commercial engine concepts. Additionally, greenhouse gas standards and CO2 limits respectively, require diesel engines with 50% brake thermal efficiency. However, EGR will still be mandatory to ensure emission compliance under an extended range of environmental conditions.
INTRODUCTION
Future worldwide emission standards not only require the reduction of local pollutant emissions, to improve especially urban air quality, but also a significant lowering of CO2 emissions in view of climate change. Upcoming ultra-low NOx legislation in North America requires the fulfillment of lowest emission limits. A NOx reduction of up to 90% from the current standard is proposed by the Californian Air Resource Board (CARB), see Figure 1 leading to highest DeNOx
conversion rates not only in the HDDTC but also in the RMC and NTE conditions. In Europe Euro VI D will be replaced by Euro VI E from September 2020 onwards, where the cold start as well as PN measurement for in service conformity (ISC) testing will be included. Recently the “Euro VII” discussion has started. Although there are no specific targets or numbers published yet, an enhanced focus will be, beside NOx and PN, put on N2O and ammonia emissions, not only in legal test cycles but also during real driving. Also in China, a significant reduction of pollutant emissions is expected.
Proposed ultra-low NOx standards in North America require a NOx reduction down to 0.02 g/bhp-hr NOx tailpipe. Additionally, CARBs objective is to develop a new low load cycle (LLC) to represent real world urban tractor and vocational vehicle operation [1]. Moreover, the implementation of in use-conformity, possibly similar to Euro VI E, to monitor real driving emissions using the moving average window method, is under discussion. Lengthening the useful life up to
550.000 miles (class 4-7) and 1.000.000 miles (class 8) respectively, requires a highly robust and reliable aftertreatment system. Although CARB has allowed to maintain the current OBD limits as long as low NOx standards are optional, a tightening of OBD limits is also expected as soon as the standards become mandatory. N2O and CH4 limits impose additional boundaries to the engine and aftertreatment layout.
Figure 1 Emission legislation commercial vehicle on-road - tentative scenario
ICPC 2019 – 2.2
29
CO2 LEGISLATION
The mitigation of the ongoing climate change, largely affected by anthropogenic carbon dioxide (CO2)-emission, is a central aspect of global environment politics. In the USA for example, the environmental protection agency (EPA) indicates the portion of the
total CO2-emissions coming from the transport sector with 26.3% [2]. In this sector commercial vehicles contribute with 22.5% and have the fastest growth rate with 75% from 1990 until 2014. In Europe the commercial vehicles contribute with 6% to the total CO2-emissions [3]. Therefore, a further increase of freight efficiency and the subsequent reduction of CO2-emissions is a crucial goal for the future.
Consequently, governments worldwide have agreed on standards for GHG, CO2 and fuel consumption limits. Figure 2 shows a worldwide overview of the CO2 legislation for commercial vehicles. The USA follow the strategy to separate vehicle and engine targets and Canada has released regulations which are similar to the USA. The EU will release vehicle limits (in g CO2/tkm) and no specific engine limits. Since 2019 the engine is included in the monitoring process together with the vehicle and powertrain components, which influence the vehicle CO2 emission. The vehicle CO2 emission will be determined by a simulation tool (VECTO). A similar approach is used in Japan. China also limits the vehicle fuel consumption, although using a different evaluation process, with the chassis dyno test being a unique approach for commercial vehicles.
ULTRA-LOW NOX REQUIREMENTS
To highlight the extraordinary requirements of the ultra-low NOx standards in combination with Phase 2 greenhouse gas standards in the USA, Figure 3 shows a comparison of the current emission legislation with future requirements for a class 8 truck.
In order to comply with the emission standard of 0.02g/bhp-hr NOx emissions, the light-off of the aftertreatment system needs to be ensured within a very short time after cold start in the US HDDTC, using low NOx engine out emissions. Even by assuming no NOx tailpipe emissions afterwards, the SCR needs to be heated up within 250s using a
calibration with 1.5g/kWh NOx engine out, respectively within 50s using 5g/kWh (see Figure 4). Considering a NOx conversion of <100%, light-off of
Figure 2 Worldwide CO2 Legislation
Figure 3 Comparison of current CO2 and NOx emission limits with future requirements in US for a class 8 truck
ICPC 2019 – 2.2
30
the SCR is mandatory no later than 150s after cold start using NOx engine out emissions <1.5g/kWh.
ENGINE AND AFTERTREATMENT CONCEPTS FOR ULTRA LOW NOX
The most promising engine and aftertreatment concepts from AVL perspective are illustrated in Figure 5 [4], [5]. Concept 1 consists of a 2-stage SCR system in combination with a variable valve train with early exhaust valve opening (EEVO) for temperature management. Usage of a DOC upstream of the close coupled SCR is optional and mainly depends on the used catalyst technology for close coupled SCR, HC poisoning and its desulfation strategy. Utilization of a box type layout is recommended for the components downstream of the close coupled SCR/ASC to keep the backpressure increase on a moderate level and for keeping synergies from the current Euro VI aftertreatment architectures. Moreover, 2-stage urea dosing allows a smart balancing of the NOx conversion, giving additional benefits in terms of passive regeneration, PN filtration efficiency and diagnostic strategy [6].
Concept 2 consists of a SDPF, again with a second urea dosing after the particulate filter. Rapid heat-up is supported by a heater with ~12kW net power. A SDPF with a single stage urea dosing is less attractive due to limited potential for passive regeneration. This leads to frequent active DPF regenerations and consequently to a more severe aging of the system and a higher fuel consumption for the end customer. Yet again, usage of 2-stage urea dosing shows advantages similar to concept 1. However, SDPF is currently not the main technology route for on-road commercial vehicles which leads to high development and validation effort. Nevertheless,
especially for applications dealing with strict packaging constraints, concept 2 might be a viable solution.
In Figure 6 a comparison of using EEVO with and without DOC, upstream of the close coupled SCR for concept 1, is plotted. Due to the thermal inertia of the DOC, the light-off of the SCR is shifted by more than 100s. Therefore, placing the SCR as a first component is recommended as long as desulfation and HC-storage of the SCR can be handled.
N2O is another gaseous emission which will soon be limited. On the one hand, N2O formation occurs on the oxidizing coating of the DOC, by incomplete reduction of NO2 due to hydrocarbons [7], [8]. Low HC engine out emissions, as well as an optimized catalyst coating technology are mandatory to reduce this effect. On the other hand, N2O is also formed on catalysts with SCR coating, again depending on the used technology [9]. Lower NOx engine out emissions automatically lead to a lower urea injection, therefore the reduction of laughing gas emissions is feasible by the adaption of engine out emissions. Moreover, the N2O emissions are subject to variation depending on the NOx conversion, which is controlled by the NH3 filling level at the SCR catalyst. An exemplary tradeoff of a typical EPA2010 aftertreatment system in US HDDTC is shown in Figure 7.
Figure 4 Required DeNOx light-off depending on different NOx engine out scenarios in US HDDTC cold cycle (assuming 100% DeNOx afterwards)
Figure 6 Influence of DOC on temperature upstream of ccSCR by usage of EEVO
Figure 5 Engine and aftertreatment concepts targeting ultra-low NOx (both equipped with cooled/uncooled HP-EGR and exhaust flap)
ICPC 2019 – 2.2
31
Highest NOx conversion rates are not only required in the HDDTC but also in the RMC and NTE conditions. As mentioned above, the potential of a SDPF with a single stage urea dosing is seen as critical due to the limited NOx conversion at full load and non-standard conditions. Especially in aged conditions, the emission reduction at high temperatures is limited (see Figure 8Fehler! Verweisquelle konnte nicht
gefunden werden.).
To compensate the weak points and use the advantages of the different SCR technologies, a combination of Fe-SCR and Cu-SCR is recommended. For the second SCR system in concept 1 and 2 a Fe/Cu-SCR hybrid combination allows a compromise between the low and high temperature performance of both formulations (see Figure 9). Usage of a small Fe-SCR portion upstream of the Cu-SCR significantly increases the high
temperature performance of the system. Disadvantages in the low temperature performance can be compensated by the usage of Cu-SCR technology for the close coupled SCR or SDPF.
Furthermore, using a 2-stage SCR system not only allows high NOx-conversion immediately after cold start but also provides additional opportunities in terms of soot load control on the filter (see Figure 10). The actual soot load on the filter defines the distribution of the overall urea dosing amount between the two SCR-stages and hence the NOx (NO2) to soot ratio upstream of the filter. In this way, the soot load can be balanced in a range that allows a high PM Number filtration efficiency and low DPF-backpressure [6], [10].
Additionally, a controls and diagnostic strategy was developed by AVL for 2-stage SCR systems. Further details are already described in the publications [6] and [10].
EFFICIENCY GOAL FOR THE ENGINE
Figure 11 shows the required fuel consumption targets derived from the US GHG Phase 1 and Phase2 legislation for heavy-duty diesel, which are representative values for all developed markets.
Figure 8 Measured NOx conversion efficiency for a Copper SDPF in fresh and aged status
Figure 10 Smart DeNOx balancing to ensure optimum tradeoff between PN filtration efficiency and backpressure
Figure 9 Advantages of Fe/Cu-Hybrid SCR combination
Figure 11 Fuel consumption targets for heavy-duty vehicles in the USA
Figure 7 Tradeoff between NOx conversion and N2O tailpipe for 2 different NOx engine out levels for a typical EPA2010 EAS
ICPC 2019 – 2.2
32
In order to achieve MY’27 CO2 limits, a cycle BSFC value of 181 g/kWh in RMC is required. Considering a margin, a minimum BSFC of 170 g/kWh is estimated, which corresponds to 50% brake thermal efficiency (BTE).
BUILDING BLOCKS
In general, a high BTE of an ICE can be realized by optimization of the indicated efficiency and reduction of friction losses. Additionally, WHR systems can exploit rejected heat, for example from exhaust gas and EGR mass flow.
The indicated efficiency is a combination of the high-pressure and low-pressure cycle efficiency.
The efficiency of the high-pressure cycle is influenced by the compression ratio, the cylinder charge mass, the combustion process itself and the wall heat losses. All these parameters affect the necessary peak firing pressure (PFP) capability of the engine. Therefore, an increased PFP capability is one of the main prerequisites for achieving a high BTE. Parameters for improvement of the low-pressure cycle (essentially pumping work) are a high volumetric and high charging efficiency, as well as lowest pressure losses in the intake and especially in the exhaust system.
The balanced optimization of both, high-pressure and low-pressure cycle is strongly influenced by the
available turbocharging efficiency, as well as the desired EGR rate and EGR concept. The EGR concept and rate dictate the necessary pressure difference between the intake and exhaust manifold.
A further reduction of friction losses of the base engine is impeded by the demand for a higher PFP capability. Nevertheless, measures on the base engine, as well as minimized parasitic losses (auxiliaries on demand) will result in a further reduction of friction losses of future commercial engines. All these building blocks are summarized in Figure 12.
Figure 12 Building blocks for a high BTE
ICPC 2019 – 2.2
33
CO2 REDUCTION ROADMAP
Figure 13 shows a reasonable scenario in view of achieving MY’27 CO2 limits. The SET (RMC) related CO2 emissions will be realized by using ”engine internal” measures only. These measures are the improvement of combustion, gas exchange and friction as well as the adaptation of operation strategy. In this case, an average improvement potential has been considered. However, additional systems such as WHR or hybridization might be implemented to meet 2027 legislative requirements. [5]
PEAK FIRING PRESSURE
As a consequence of “engine internal” measures for CO2 reduction, the PFP capabilities of the base engine need to be increased to levels in the magnitude of 280 bar (see Figure 14).
EXHAUST GAS RECIRCULATION
The measures for meeting the required CO2 and fuel consumption targets affect the boundary conditions for the aftertreatment system, such as exhaust gas temperature and NOx engine out level.
The main factors to improve the gas exchange are the charging and EGR system. Therefore, one of the main focuses is the increase of turbocharger efficiencies to reduce gas exchange losses. State of the art charging systems have an efficiency of 50 to 55%. Future charging systems are expected to have efficiencies in the range of 60% and higher.
With such improved charging system efficiencies, it becomes increasingly challenging to generate the required EGR rates for NOx reduction, with high-pressure EGR systems only. Currently discussed counter-actions will require alternative EGR systems, such as EGR pumps or low-pressure EGR systems, additionally to (existing) high-pressure systems.
Figure 15 shows the NOx BSFC trade off measured on a R&D HD diesel engine at the load point 1200 rpm full load, in which the boost pressure and exhaust pressure level was kept constant. The blue curve represents a variation of injection timing without EGR. Obviously the minimum BSFC without EGR is reached at a high NOx engine out level. EGR is an enabler to realize the combination of low BSFC at low NOx emission. The red line represents an EGR sweep at optimal injection timing. In addition, the EGR technology provides a flexibility in NOx engine out in order to react to different EAS boundary conditions. Therefore, EGR becomes mandatory for future engine concepts.
Figure 13 Roadmap for CO2 reduction [5]
Figure 14 Peak Firing Pressure increase
Figure 15 BSFC - NOx trade off; w/ & w/o EGR
ICPC 2019 – 2.2
34
EXHAUST GAS TEMPERATURE
Figure 16 shows the tradeoff between BSFC and cylinder mass ratio (CMR, detailed description in publication [11]) for different TC efficiencies at an engine operation point of 1200 rpm - 25% load. The higher the TC efficiency, the higher the CMR for an optimal balance between high pressure and low-pressure cycle. A high TC efficiency is therefore not only a prerequisite for the reduction of pumping losses, but also for an improved high-pressure cycle.
The trend towards higher cylinder mass, either driven by the high TC efficiency or by the necessity of a reasonable EGR rate, reduces the exhaust gas temperature downstream of the turbine (see Figure 17). Therefore, the conflict between a high BTE, reasonable NOx engine out emissions and a sufficient exhaust gas temperature for the EAS becomes progressively challenging.
GAS ENGINE AS ENABLER FOR CO2 AND NOX REDUCTION
Due to its chemical composition, natural gas offers a theoretical CO2 reduction potential of 25% compared to diesel fuel, assuming the same fuel energy provided. Additionally, natural gas also offers a great reduction potential for pollutant emissions.
Gas engine technologies for commercial engines are available on the market. The two most promising technologies for mastering future requirements, regarding pollutant criteria and GHG emissions reduction, are the stoichiometric approach and high-pressure direct injection (HPDI).
Stoichiometric approach
Compared to a diesel engine, the overall efficiency of the stoichiometric gas engine is lower. In its sweet spot a stoichiometric commercial gas engine can reach 40% BTE which results in 13% lower CO2 emissions compared to a HD diesel reaching 46.5% BTE. However, the benefits are mitigated in the partial load due to throttling losses and lower cylinder mass. Nevertheless, in a low load cycle such as the WHTC, a CO2 benefit remains.
On the one hand, the low efficiency in the partial load is a weakness of the stoichiometric engine. On the other hand, the usage of a three-way catalyst offers a great potential for pollutant emission reduction. CARB recently published that all 10 engines, certified to the 0.02 g/bhp-hr optional NOx standard in California, are natural gas or liquefied petroleum gas powered engines. [12]
High pressure direct injection
HPDI means high pressure direct injection of natural gas. The gas burns on a diffusion flame. A diesel pilot provides ignitable conditions for the natural gas in the combustion chamber.
Natural gas therefore burns on a similar excess air ratio as diesel. Compared to premixed lean burn concepts, HPDI can operate significantly leaner. Hence the diffusion combustion of gas can avoid BMEP limitations due to knocking issues and avoid CH4 slip from flame quenching, crevice losses and scavenging.
All in all, HPDI combines the benefits of a diesel combustion process with the beneficial chemical compositions of natural gas.
Project HDGAS 2020 AVL, funded by the EU, demonstrated more than 22% CO2 reduction by high pressure direct injection of natural gas on a heavy-duty engine with 200 bar PFP capability. [13] In case
Figure 16 Trade-off BSFC – Cylinder mass ratio at an engine operation point of 1200 rpm – 25% load
Figure 17 Exhaust gas temperature decrease by increased cylinder mass
ICPC 2019 – 2.2
35
of a maximum PFP of 200 bar, a 300 bar injection pressure was sufficient. As described previously the PFP of the future diesel engine will rise, hence also the injection pressure of HPDI will have to increase, if HPDI is to maintain similar power density and efficiency as diesel engines.
CONCLUSION
In order to comply with future ultra-low emission legislations, the modification of current aftertreatment architecture becomes mandatory. The focus will be to achieve high NOx conversion in the cold part of the legal cycle as fast as possible by a combination of engine and aftertreatment measures. AVL sees the combination of thermal management by a variable valve train with early exhaust valve opening, together with a close coupled SCR system as the most promising technology route. A possible alternative is a concept including SDPF with 2 stage urea dosing and a heater for thermal management purpose.
In order to fulfill current CO2 requirements, a HD diesel engine has to reach a minimum BSFC in the range of 180g/kWh, which corresponds to a BTE of 46.5%. From today’s perspective 50% BTE is feasible using only “engine internal” measures. Enablers are an advanced combustion and an improved air & EGR path. As a consequence, the peak firing pressure levels will be increased, and the exhaust gas temperatures will be reduced. Therefore, a new engine design requires a high PFP capability, as well as effective heat up and efficient keep warm exhaust gas temperature measures.
REFERENCES
[1] California Air Resources Board, "Heavy-Duty Low Nox," California Air Resources Board, 22 January 2019. [Online]. Available: https://www.arb.ca.gov/msprog/hdlownox/hdlownox.htm. [Accessed 16 April 2019].
[2] Environmental Protection Agency, "Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles—Phase 2," 2016.
[3] European Comission, "Comission Staff Working Document Impact Assessement," European Comission, Brussels, 2018.
[4] M. Decker, H. Theißl, J. Schubert and W. Schöffman, "The Commercial Vehicle Engine of the Future Considering Emission Legislation," MTZ Worldwide, no. 11, pp. 26-31, 2017.
[5] L. Walter, T. Wagner, H. Theissl, S. Flitsch and G. Hasenbichler, "Impact of CO2 and ultra-low NOx legislation on commercial vehicle base engine," in 4th International Engine Congress 2017, Baden-Baden, 2017.
[6] M. De Monte, S. Mannsberger and H. Noll, "SCR control strategies with multiple reduction devices for lowest NOx emissions," in Heavy-Duty Diesel Emissions Control Symposium, Gothenburg, 2018.
[7] A. Beichtbuchner, L. Bürgler, H. Wancura, M. Weißbäck, J. Pramhas and E. Schutting, "HSDI Diesel on the way to SULEV - Concept Evaluation," in 21st Aachen Colloquium Automobile and Engine Technology, Aachen, 2012.
[8] A. Beichtbuchner, L. Bürgler, E. Schutting, K. Hadl and H. Eichelseder, "Diesel-Abgasnachbehandlungskonzepte für die Richtlinie LEVIII SULEV," in Internationaler Motorenkongress, Baden-Baden, 2015.
[9] A. Newman and J. Matthey, "High Performance Heavy Duty Catalysts for Global Challenges beyond 2020," in Heavy-Duty Diesel Emissions Control Symposium, Gothenburg, 2018.
[10] B. Brier, M. Tandl, A. Grauenfels and G. Graf, "Impact of particle number limitations on engine and exhaust aftertreatment layout," in 10th INternational Exhaust Gas and Particulate Emissions Forum, Ludwigsburg, 2018.
[11] H. Theissl, H. Seitz, G. Gradwohl and T. Sams, "Die Aufladung als Schlüssel zur weiteren Verbrauchsreduktion am modernen Nutzfahrzeug-Dieselmotor," in 19. Aufladetechnische Konferenz, Dresden, 2014.
[12] S. o. t. M. S. Control, "CARB Staff Current Assessment of the Technical Feasibility of Lower NOx Standards and Associated Test Procedures for 2022 and Subsequent Model Year Medium-Duty and Heavy-Duty Diesel Engines," CARB, California, 2019.
[13] A. Arnberger and A. Prochart, "HDGAS D7.1 - Assessment results of independent testing," EU Comission, 2018.
36
ICPC 2019 – 2.3
Development and testing of an innovative gas engine for heavy duty applications
Stefano Golini, David D’amato, Sergio Giordana, Paolo, Grosso, Diego Iudice
FPT Industrial
Anton Arnberger, Gernot Hasenbichler
AVL List GmbH
Davide PAREDI
Politecnico di Milano
Peter Grabner
TUG
Copyright © 2019 FPT Industrial, AVL List GmbH and SAE International
ABSTRACT
The need to drastically reduce GHG emission in the next decade will deeply change the technological solutions employed for long haul transportation. Several alternatives are possible and, among them, natural gas engines have proved a reliable and efficient way to curb GHG emission.
FPT Industrial is currently the European leader in the production of NG engines and joined the research project HDGAS (co-funded by the EU), aimed at the development of NG powertrains for the 2020s, to offer NG engines with increased fuel efficiency.
This paper describes the challenges encountered during the development of the HDGAS engine and presents results of the simulations and testing performed during the project.
INTRODUCTION
At the end of 2018 the European Council introduced limits on CO2 emissions from HD vehicles: compared to the 2019 average, a reduction of 15% is foreseen in 2025, which will become 30% in 2030.
Compared to the uniformity of today’s HD vehicles (100% ICEVs, diesel engines > 99%), in 10 to 20 years the landscape will be significantly more varied, because it will be impossible to meet these limits relying only on the development of the diesel engine.
A revolution will take place in the next few decades, which will bring about different vehicles and fuels to move goods across the world.
Electrical vehicles seem to be the most probable candidate to replace ICEs in the near future. It must be underlined, though, that the battery efficiency decreases as the vehicle size increases [1] [2]: this means that BEVs could be a viable options for LCV but it will be more difficult for them to replace ICEs in LH applications. Furthermore, the technical principles for the electrification of trucks are similar to those available for cars but the greater size and weight of trucks and their more rugged operations substantially increase the barriers to batteries serving as a substitute for diesel engines [2].
It must be underlined that the impact on the environment of this technology is not negligible: the LCA of BEVs shows that they have a global effect similar to traditional vehicles [3]: this is highly dependent on the way electricity is produced [4] and with the current European mix, in which renewable energy accounts only for 26% of the total [5], the positive effect of BEVs on global warming is very limited [1]. In the current situation, BEVs can be effective in reducing the pollutants level in urban areas: this factor must not at all be underestimated but will have little or no effect in reducing GHG emission [3].
In addition, batteries need raw materials, such as lithium and cobalt, whose production must be
ICPC 2019 – 2.3
37
increased substantially in order to meet the global demand of BEVs and there is a risk that large scale exploitation of these resources could lead to significant environmental impacts [4]. What’s more, the effect on water reserves must in no way be overlooked.
Fuel cells are another candidate foreseen to replace the ICE, at least partially, on LH missions. An FCV is, essentially an electric vehicle using hydrogen stored in a pressurized tank and equipped with a fuel cell for on-board power generation. Hydrogen is stored on vehicles in dedicated tanks at pressures of 35 MPa to 70 MPa: the energy density is much higher compared to batteries, but hydrogen storage still needs four times more space to achieve the same range as conventional diesel technology [2].
Today, around 50% of hydrogen is produced from natural gas through steam methane reforming, and one-third comes from the refining process of oil; the rest is produced from either coal or electrolysis [2]. From this, it follows that the ideal pathway for hydrogen production is electrolysis, using renewable energy. Alternatively, biomethane and the use of carbon capture and storage also provide another way to generate hydrogen with low life cycle GHG emissions [2].
Currently, there around 500 FCVs (mainly cars and buses) running across several demonstration projects globally, but the interest in hydrogen and FCVs is growing: up to 400 stations are planned to be operating in Germany by 2023 while California has set the goal of having 100 stations by 2020 and has developed funding programmes to achieve this target [2]. Nevertheless, it must be considered that the time needed to bring hydrogen-refuelling stations online is significant (California estimates it at two years [6]) and that refuelling is, in any case, a very complex operation, especially when using 70 MPa.
The high cost of the main components is another barrier that must be overcome. Current cost of FCs is around 1000$/kW and it will be necessary to wait for high-volume manufacturing of next generation of FCs to bring the cost somewhere between 60 and 200 $/kW [2]. The tank is another very expensive item, ranging from 40 to 60 $/kWh (at 70 MPa): a storage
tank of 1400 kWh, that should guarantee a 700-km range, will then stay between 56000 and 84000 $. Costs are expected to fall to 15-30 $/kWh, though at a slower pace compared to FCs [2].
The time necessary to build the infrastructure for the new vehicles, be they BEVs or FCVs, is a factor that must be fully accounted for, as more than few years will be necessary to put in operation the over 25000 charging points (20000 DC 150-500 kW and > 5000 DC >500 kW, along motorways) and the 1000 hydrogen refueling stations (500 for compressed H2 and 500 for liquefied H2) that are estimated as necessary by 2025-2030 to meet the EU standards on CO2 [7].
In the meanwhile, decarbonisation will have to be pursued reducing ICE’s GHG emission and this can be accomplished reducing the carbon content of the fuel: natural gas (a blend of different hydrocarbons, mainly methane) is the immediate replacement for diesel fuel.
To begin with, combustion of NG produces the lowest CO2 quantity per unit of energy of all other hydrocarbons [8]: due to the fact that NG has the lowest C/H ratio and the highest energy content per unit of mass, its combustion generates 58.5 gCO2/MJ versus 78 gCO2/MJ for diesel fuel, a reduction around 25%, assuming the same thermal efficiency. The higher efficiency of the diesel engine lessens this amount, but it remains still significant: a recent study [9] showed that, on a well-to-wheel basis, a HD NGV using CNG will produce 16% less CO2 than the corresponding diesel vehicle.
Moreover, NG can be obtained totally from renewable sources: the number of biomethane plants in the EU rose from 180 in 2011 to 420 in 2015 [2] and biomethane is obtained from agricultural residuals or from landfills, so it is not in competition with food. If NG is obtained from renewable sources, GHG emission will be, on the average, 23% of GHG emission with fossil NG [9].
Since NG technology has been around for the past few decades, the distribution network is well established and it is continuously growing (Figure 1).
ICPC 2019 – 2.3
38
Figure 1 Infrastructure of “alternative fuels” for HDV [7]
NG HDVs have been available for the past twenty years and the most recent products, such as the IVECO Stralis NP460 (powered by FPT’s Cursor13 NG), can replace the correspondent diesel vehicle, both in terms of performance and in terms of range (more than 1600 km with two LNG tanks [10]). Furthermore, the use of NG can lead to important savings on the fuel cost: LNG price in China in the past decade has been, on the average, 55% of diesel fuel price, on an energy equivalent basis and the number of LNG lorries skyrocketed from 7000 in 2010 to 132000 in 2015 [2]. But also in Europe, NG is significantly cheaper than diesel fuel and can tip the overall economic balance in favour of the LNG vehicle [10].
The already significant advantages of NGVs in terms of lower GHG emissions and lower operating cost can be improved by improving the efficiency of NG engines. FPT Industrial has developed NG engines since 1990s and strongly believes that this engine is one of the possible solutions (certainly the most readily available) to reduce the environmental impact of transportation.
In order to reach this target and to offer to its Customers more efficient and economically viable products, FPT Industrial joined the HDGAS project, aimed at developing innovative gas engines for the 2020s.
THE HDGAS PROJECT
The HDGAS project started in May 2015 and lasted 36 months. It was co-funded by the EU in the framework of HORIZON2020 and it involved 20 partners from 9 different countries across the EU, from both the academic and the industrial world.
Its goal was to develop, demonstrate and optimise advanced powertrain concepts for NG engines, to perform thereof integration into HD vehicles, and to confirm achievement of Euro VI emissions limits, and in use compliance under real-world driving conditions, while reducing CO2 emissions at least 10% with respect to 2013 state-of-the-art engines.
Three different ICEs were developed in the project along with innovative after-treatment systems. Moreover, a new concept of LNG tank was pursued, in order to increase vehicles’ range. Finally, technical requirements and international/European standards for LNG fuelling interfaces were drawn.
Project Organization
In order to achieve the above-mentioned goals, the HDGAS project was organised in 8 work packages (WP), as shown in Figure 2Fehler! Verweisquelle konnte nicht gefunden werden.:
ICPC 2019 – 2.3
39
Figure 2 HDGAS structure
• WP1 (led by AVL and Uniresearch) to manage the Project
• WP2 (led by Daimler) aimed at the development of advanced tank systems as well as standardization of fuelling process and interface
• WP3 (led by Ricardo) aimed at the development and demonstration of a new generation of ATSs
• WP4 (led by FPT Industrial) aimed at the development of an innovative positive ignition NG engine
• WP5 (led by MAN) aimed at the development of a dual-fuel, port-injected engine
• WP6 (led by Volvo) aimed at the development of a high-pressure gas injection engine
• WP7 (led by AVL) to determine testing procedures and overall results assessment
• WP8 (led by Uniresearch) to disseminate Project’s results.
Prof. Dr. Theodor Sams, from AVL Graz, was the Project Coordinator. Further information can be found at the Project’s website (www.hdgas.eu).
In particular, WP4, led by FPT Industrial, was devoted to the development of an innovative positive-ignition engine exclusively fuelled by natural gas, and the integration of the engine in a long haul truck, along with the new LNG tank developed in WP2 and the innovative ATS developed in WP3.
Tests aimed at demonstrating the improved fuel efficiency were performed at test bench. The engine was tested in two different configurations, stoichiometric and lean burn, in order to evaluate potentialities in fuel consumption reduction of both but in this paper we will concentrate only on the stoichiometric version.
ICPC 2019 – 2.3
40
The target of -10% in GHG emissions and +10% in performance (torque/power) with respect to 2013 state-of-the-art engines was reached applying several new solutions to the HDGAS engine, such as:
• An innovative combustion system, with the intake ports and the combustion chamber specifically designed for combustion in spark-ignition engines, hence creating tumble rather than swirl
• A new fuel system, which makes it possible to employ different injection strategies in order to improve air/fuel mixing and, thus, combustion efficiency, reducing pollutant emissions at the same time
• Cooled EGR, to increase fuel efficiency
• High energy ignition system. With the Corona ignition system, the air/fuel mixture is ignited in a larger volume compared to a standard spark plug ignition system, so burn delay and burn duration can be significantly reduced, leading to a swifter combustion and improved late burn behaviour, reducing the risk of knock
• Variable Valve Timing, using a cam-phaser, on both the intake and the exhaust. Hydraulic valve lash adjustment was also employed
• Double overhead camshaft with inclined valves. The high level of new content of this WP required the joint effort of several partners, each with a different role and task:
• FPT Industrial designed the new engine components and procured and built the prototype multi-cylinder engines. FPT also developed the stoichiometric configuration at test bench
• AVL tested the stoichiometric version on a single cylinder research engine
• IVECO integrated the HDGAS engine in the demonstrator vehicle, along with the new LNG tank and ATS
• BorgWarner supplied the high-energy Corona ignition system
• Politecnico di Milano performed CFD simulations of the stoichiometric configuration to assist the design of the combustion system
• Ricardo performed 1D and CFD simulations of the lean burn version and developed the same configuration at test bench
• Technische Universität Graz performed 1D simulations of the stoichiometric version to determine the best configuration of the engine in terms of subcomponents (EGR lay out, turbomachting, camshaft profile,…).
THE DESIGN PROCESS
It was clear from the beginning that the design of the HDGAS engine would have been a complex task, due to the features which required a totally new cylinder head as well as other fundamental components.
Some constraints were defined:
• First of all, the new cylinder head would have to be installed on the existing cylinder block, so the number and the position of the bolts as well the number and position of oil and water passages were fixed
• Secondly, the external dimensions of the new engine would have to be as close as possible to the Cursor13 NG engine, under development at the time
• Finally, the vehicular interfaces of the new engine would have to be the same (dimensions and position) of the aforementioned Cursor13 NG
The main characteristics of the engine are listed below.
Architecture 6-cylinder in line
Bore x Stroke 135 x 150 mm
Displacement 12.9 dm3
Valves per cylinder 4
Camshaft lay-out Double over-head
Valve drive Finger follower
As we will see, the final configuration of the engine derived from a close cooperation between design and 1D and CFD calculations.
The Combustion System
The design of the combustion chamber is based on the pent roof concept, which has been proven to be the best configuration for spark-ignition engines, from the efficiency of combustion point of view [12].
The design of the combustion chamber had to take into account the necessity to install the fuel injector and Corona ignitor, which are rather bulky objects: the two components were arranged in a configuration which allows good accessibility (for installation and maintenance) while keeping them as close as possible to the centre of the combustion chamber, to improve air/fuel mixing and to facilitate the mixture’s ignition.
The final configuration of the combustion chamber is shown in Figure 3.
ICPC 2019 – 2.3
41
Figure 3 Combustion chamber
The intake ports were designed in order to reach the best values of tumble ratio and discharge coefficient: the latter is a measure of the turbulence level (beneficial for combustion propagation) in the combustion chamber, while the former quantifies the mass flow through the ports and into the cylinder.
The proposed design was checked with CFD, in order to find suitable values for both parameters. The discharge coefficient thus found was then fed into the 1D model in order to verify that it guaranteed a correct global behaviour of the engine.
As tumble ratio and discharge coefficients have opposite trend, the best trade-off was found after three iterations between design, CFD and 1D simulations: the final configuration is shown in Figure 4 (see also Figure 19).
Figure 4 Final configuration of the intake ports
The piston head was shaped in a lenticular way, in order to reach the desired compression ratio and pockets are present on the piston ceiling to avoid interference with valves at TDC.
The Cylinder Head and Overhead
The cylinder head is the core component of the C13 HDGAS, and it incorporates all the new solutions introduced in this engine, namely:
• Pent roof combustion chamber
• Inclined valves
• Direct injection system
• Corona ignition system. The experience gained by FPT in more than ten years of designing high-performance NG engines greatly helped with this cylinder head. Therefore, some components (both geometry and material of valves and valve seats) and the cylinder head material are the same successfully used in other Cursor NG engines. The cylinder head material is a cast iron variant, particularly suitable for high temperatures found in stoichiometric combustion.
Figure 5 Cylinder head
FEA of the cylinder head, conducted according to FPT’s standard practice, showed that the component can successfully withstand the thermal and mechanical loads expected during its mission.
The cylinder overhead is a large aluminum component which has multiple functions:
1. It houses the camshafts and the HVA
2. It serves as the cylinder head cover
3. It has a central, oil-free to room where the upper parts of the ignitors and of the injectors, and their electrical connectors, are located. The injection rail is also located here
4. It has an integrated rear pocket to accommodate chain drive, cam phaser and variable force solenoid.
The axial dimension of the camshaft journals has been kept to a minimum, in order to reduce friction. Moreover, the use of HVA eliminates the need for valve lash adjustment, thus reducing maintenance.
Figure 6 Cylinder overhead
ICPC 2019 – 2.3
42
Gear Train and Back End
The back end of the engine was also deeply modified, as this is the first Cursor engine to employ a double camshaft. Because of this, the gear train currently used on the Cursor13 engine was revised and it is still used in the lower part, close to the crankshaft, while a chain is used in the upper part to drive the two camshafts.
The flywheel housing was completely redesigned to house the new components.
Figure 7 Back end
Intake Manifold
The intake manifold consists of two elements joined together: the fresh air-EGR mixer and the plenum.
In the mixer, fresh air enters through the throttle valve, coming from the charge air cooler, while EGR is added by the EGR nozzle, after it has passed through the cooler and its valve. The position of the EGR nozzle was determined with the aid of CFD calculation to obtain the optimal mixing between EGR and fresh air.
Figure 8 Intake manifold and EGR circuit
The plenum is connected to the cylinder head by means of 12 straight ducts, designed in order to reduce pressure losses to a minimum and to keep charge flow into the various cylinder as uniform as possible.
Exhaust Manifold and EGR Circuit
The EGR circuit is used to recirculate exhaust gas to the intake of the engine in order to reduce gas temperature during combustion, thus lowering NOx production, wall-heat losses and sensitivity to knock; moreover, EGR reduces pumping losses in part-load operation [12].
As it is customary with 6-cylinder engines, the turbocharger has a twin scroll, to avoid interference between pressure pulsations of the various cylinders. Therefore, it was decided to extract the EGR from both branches of the exhaust manifold. For the same reason, the turbocharger is equipped with two WGs, one for each turbine scroll: this configuration improves the engine efficiency, keeping both sections of the engines (i.e. cylinders 1 to 3 and cylinders 4 to 6) in the same conditions
The EGR routes are separated down to the EGR cooler and they are joined together only upstream the EGR control valve; reed valves are used to eliminate pressure fluctuations.
The FEA of the exhaust manifold showed positive results for this component too.
Figure 9 Exhaust manifold, TC and EGR cooler
External Packaging
The external shape and dimensions of the Cursor13 HDGAS engine were kept as much as possible similar to the current Cursor13 engine. Most interfaces are in the same position as those of the Cursor13 (intake duct upstream of the throttle valve,
ICPC 2019 – 2.3
43
turbine and compressor outlets) and the lay-out of the external components (turbocharger and exhaust manifold, EGR cooler and circuit) was designed in order to avoid interferences with the vehicle.
The result is a compact and elegant engine which can easily fit in the IVECO Stralis frame.
Figure 10 Cursor13 HDGAS engine
THERMODYNAMIC ANALYSIS
Figure 11 Simulation model of the HDGAS engine [13]
The 1D engine simulations were performed at the beginning of the project to define the thermodynamic layout of the HDGAS engine. This included valve timing, so different concepts for the gas exchange, like Early and Late Miller timing, were evaluated. Moreover, the turbocharger matching and the definition of the EGR layout were performed: for these purposes, a 1D simulation model was created with AVL BOOST v2013.2 software. Model calibration is an essential part of 1D engine simulations and, since at the time of the simulations the HDGAS engine did
not exist, the model was calibrated and validated against measured data of an existing FPT NG engine. Later the model was adapted to the requirements of the HDGAS engine (Figure 11).
EGR in Stoichiometric SI Natural Gas Engines
With the introduction of the EURO VI emission legislation, the operating mode of natural gas positive ignition engines was shifted from lean towards stoichiometric operation. Thereby, a three way catalyst can be used to comply with the very stringent emission limits. However, stoichiometric operation entails negative effects on the fuel efficiency and the thermal strain of the engine. EGR has received attention for the application in NG positive ignition engines to mitigate these penalties [14][15], due to its multiple effects.
Recirculated exhaust gas dilutes the fresh charge, increasing the inert mass in the combustion chamber and lowering the combustion temperature: as a consequence, also the exhaust gas temperature is reduced, and this lessens the thermal stress on several engine components, especially at the turbine inlet, which is critical at full load operation. The reduction of combustion temperature leads to a decrease of wall-heat losses and this increases fuel efficiency. In addition, cooled EGR reduces the knocking probability: thereby, the compression ratio of the engine can be raised and the combustion can be advanced to increase efficiency. Furthermore, the caloric properties of the charge during compression are altered: the isentropic exponent and the compression work is reduced, and fuel efficiency benefits from this.
Finally, the intake manifold pressure must be raised, when EGR is added, to maintain the load. In partial load operation this results in de-throttling and a reduction of the gas exchange losses. Also at full load operation the gas exchange losses can be reduced in combination with a waste gate turbocharger. The higher boost pressure leads to closing of the waste gate and, because of EGR, the turbocharger operates in an area of better efficiency
A trade-off exists between the gas exchange losses and the achievable EGR rate, for a given EGR layout. A positive pressure gradient between exhaust manifold and intake manifold is required to recirculate exhaust gas. The higher the amount of EGR, the higher the required pressure gradient and thus the higher the gas exchange losses. Several EGR layouts were evaluated to minimize the pressure losses over the EGR duct and thus limit the required pressure gradient: Figure 12 shows the chosen configuration which outperforms the other variants investigated and is the only one capable of getting close to the EGR target curve, defined for each
ICPC 2019 – 2.3
44
engine speed at full load operation (curve d in Figure 13).
Figure 12 The chosen EGR layout [13]
Figure 13 Calculated EGR rate with different layouts vs. target [13]
The Effects of EGR at Partial Load
The simulations results with and without EGR are shown in Figure 14Fehler! Verweisquelle konnte nicht gefunden werden. to quantify the effects of EGR. The part load operation point at 1200 rpm and 8 bar BMEP is chosen for this comparison. In this condition the engine is throttled and, with EGR, the intake manifold pressure must be raised by 200 mbar in order to maintain the load. The exhaust manifold pressure remains almost unchanged, consequently the gas exchange losses decrease by 200 mbar. The reduction of the combustion temperature is observed in the wall heat losses (-13%) and the exhaust gas temperature (-120 degC). The reduction of the wall heat losses and the change in the caloric properties of the cylinder charge cumulate and increase the gross indicated efficiency by 1.2%Pt. The sum of all
described effects results in a rise of the net indicated efficiency, by 1.9%Pt. [13]. These results clearly demonstrate the positive effect of EGR on fuel efficiency and thermal stress of natural gas positive ignition engines and confirm the results published in literature.
Figure 14 The effects of EGR at partial load operation [13]
Early and Late Miller Valve Timing
Apart from conventional valve timing, which is optimised for maximum volumetric efficiency, the Early and Late Miller (a.k.a. Atkinson) cycle were investigated: they are characterised by an early, and, respectively late intake valve closing (IVC) while, from a thermodynamic point of view, the processes are identical.
Compared to a conventional valve timing, the early IVC allows overexpansion of the fresh charge, which is then compressed again but the compression above intake conditions only starts when the piston again reaches the position it had at IVC: this reduces the volumetric efficiency, de-throttling the engine and decreasing gas exchange work.
Charge temperature undergoes the same changes, therefore it is lower, at a given crank angle, compared to standard valve timing: this beneficially affects the conflict between knock, compression ratio and maximum attainable load [13].
ICPC 2019 – 2.3
45
Figure 15 Valve lift profiles
The described effects, valid for Early Miller timing, also apply to Late Miller timing.
Figure 15 shows the intake and exhaust valve lift profiles used for the simulations.
The effects of early and late Miller in rated power conditions (1900 rpm-370 kW) are shown in Figure 17: keeping the temperature at the intercooler outlet constant, the in-cylinder temperature at firing with “Early Miller” profile is between around 30 degC lower than with the standard profile, while with “Late Miller” profile the reduction is around 10 degC [13].
The intake manifold pressure must be raised by more than 500mbar with “Early Miller” timing and by 300mbar with “Late Miller” timing. Contrary to the EGR case, the exhaust manifold pressure also rises considerably, therefore, the reduction of the gas exchange losses is lower, always compared to the no EGR vs.EGR case.
The reason is the turbocharger efficiency, as demonstrated in Figure 16Fehler! Verweisquelle konnte nicht gefunden werden.: the introduction of EGR shifts the operating points of the compressor towards higher efficiency, from the black curve to blue one, so that the compressor works in optimal conditions. With both Miller timings too the compressor works close to the optimum, but the difference, compared to the EGR case, is very small, and the efficiency remains approximately constant, because the maximum has already been reached [13].
Figure 16 The compressor operating map and the operating points at full load with different valve timings [13]
The influence of Miller timing on the net indicated efficiency, which includes the positive effect on the gas exchange losses, is shown in Figure 17: “Early Miller” timing increases the efficiency by 0.3%Pt at 1900 rpm while with “Late Miller” profile the improvement is 0.1%Pt [13].
Figure 17 Effects of different valve profiles at rated power [13]
ICPC 2019 – 2.3
46
Finally, Figure18 depicts the p-V and T-V diagrams: IVC is defined at 1 mm effective valve lift and added in the graphs. The overexpansion in the case of “Early Miller” timing, the higher intake manifold pressure and the lower charge temperature are well observed [13].
Figure 18 The p-V and T-V diagrams for Early Miller, Late Miller and standard timing [13]
CFD SIMULATIONS
CFD simulations were carried out using the open source OpenFOAM® technology coupled with the LibICE, which consists of a set of applications, solvers and libraries specifically developed during the years at the ICE Group of Politecnico di Milano. Such numerical methodology was extensively validated in previous works [16][17][18]. Simulations were performed using a Reynolds-averaged Navier-Stokes turbulence modelling approach.
The work activity was divided into three steps:
1. At first, steady-state flow bench simulations were performed. Different configurations of the engine intake ports were tested to find the best compromise between engine tumble intensity and flow discharge coefficient
2. Different engine operating points and valve lift profiles, at partial and full-load conditions, were tested by means of transient cold-flow, full-cycle simulations. The evolution of in-cylinder tumble motion and turbulent kinetic energy were assessed
3. Finally, fuel injection was introduced and the efficiency of the air-fuel mixing process was evaluated taking into account the homogeneity level of the mixture inside the combustion chamber. One engine operating point at partial load was tested, as well as the full-load condition with two different intake valve lift profiles.
Steady-State Flow Bench Simulations
Proper in-cylinder filling and charge flow motion intensity are fundamental to have a stable and efficient combustion process, so steady-state flow bench simulations focused on the evaluation of the Flow Coefficient (Cd) and the Tumble Ratio (TR). The former was expressed in a normalized form according to
where ṁ is the measured mass flow rate while ṁth is the maximum theoretical mass flow rate defined as
where:
Z Number of valves
dv Valve inner seat diameter
p Pressure drop across the valve
Air density
TR was defined as
where 𝜔𝐹𝐾 and 𝜔𝑀𝑜𝑡 are respectively the angular velocity of solid body rotation and the engine angular speed.
ICPC 2019 – 2.3
47
Figure 19 Evolution of intake ports layout [19]
Figure 19Fehler! Verweisquelle konnte nicht gefunden werden. reports the three different ports layouts tested under steady-state flow bench conditions. Layout (a) represents the initial geometry, while (b) and (c) represent the modifications which were carried out on the basis of the results of CFD simulations. Layout (b) is characterized by a larger section aimed at enhancing the mass flow rate. Layout (c) displays intake ducts which are more oriented towards the opposite cylinder wall, similar to geometry (a), but with an increase of the flow cross sectional area close to the caps of the valves stems.
Overall, Figure 20 demonstrates the capability of layout (c) to provide a good compromise between the discharge flow coefficient and the tumble motion intensity so this configuration was employed for further simulations and was used for the cylinder head casting.
Figure 20 TR and Cd for the different layouts of the intake ducts [19]
Full-Cycle Cold-Flow Simulations
Once the geometry of the intake ports was defined, the second step was the simulation of the flow field in the cylinder with moving boundaries, during a whole working cycle, not taking into account fuel injection and combustion.
The aim of this simulation is the analysis of the flow motion evolution during intake and compression strokes in order to determine the conditions (mainly turbulence level, to guarantee a complete and fast combustion) in the proximity of the igniter at ignition timing.
The operating condition which were analysed are listed below.
Full load 370 kW @ 1900 rpm
Full torque 2200 Nm @ 1000 rpm
Partial load 100 kW @ 1200 rpm
Calculations were started at 335 deg CA with a timestep of 0.005 deg CA.
Boundary conditions derived from 1D analysis were imposed. The in-cylinder TR was evaluated according to the methodology proposed in [20].
Valve lift profiles are shown in Figure 15.
Figure 21 displays the TR trend for the full-load operating condition with the “Early Miller”.profile.
Figure 21 TR evolution: full-load [19]
The shape of the curve is consistent with what was achieved in previous full-cycle simulations of DI engines [21], with a peak during the intake phase, a decrease and then a lower peak before the end of the compression phase.
It was then decided to compare the evolution of the turbulence level for different intake valve lift profiles.
ICPC 2019 – 2.3
48
Figure 22 shows the result for “Early Miller” vs. “Late Miller” profile: it is quite evident that the “Late Miller” profile exhibits a higher level of turbulence (i.e. TKE) during the last phase of the compression stroke, and this should guarantee a faster flame propagation, which will result in higher engine efficiency. The difference arises because, with the “Early Mller” profile, the lower valve lift combines with the early IVC to destroy quite quickly the big-scale structures: as a consequence, this leads to a turbulence decay in the first part of the compression stroke. With the other two profiles, and especially in the “Late Miller” case, the intake valves remain at the maximum lift (which is considerably higher than in the “Early Miller” profile) for a long interval: the result is a macro-vortex which remains basically unchanged during the piston descent and which is “compressed” when the piston moves toward TDC, so that the macro-scale vortex is converted to small-scale turbulence, as demonstrated by the second peak in Figure 22Fehler! Verweisquelle konnte nicht gefunden werden.. Contrary to what was found in the 1D analysis, the “Early Miller” timing seems to negatively affect the combustion process compared to the Standard or the “Late Miller” profile.
Figure 22 TKE evolution for two different valve lift profiles, full load : (a) “Early Miller”, (b) “Late Miller” [19]
Full-Cycle Simulations with Natural Gas Injection
The influence of gas injection on the efficiency of the air-fuel mixing process was then evaluated.
Different engine operating conditions were considered and multiple valve lift profiles were used to verify the effects on mixing. The conditions simulated were:
1. 1300 rpm, 2 bar BMEP with “Early Miller” profile
2. Full-load with “Early Miller” profile
3. Full-load with “Late Miller” profile.
Natural gas with a volume fraction of 84.7% in methane was injected through a centrally mounted, multi-hole, direct injector with a pressure of approximately 20 bar.
The different SOI timings used are listed below
1300 rpm-2 bar 424 deg CA
444 deg CA
Full load (both profiles) 413 deg CA
The computational mesh was refined to better capture the complex phenomena occurring during the injection phase and its interaction with the air flow.
The efficiency of the air-fuel mixing process was evaluated in terms of:
• Relative air-fuel ratio Lambda, defined as
Since each case was simulated under stoichiometric conditions, Lambda was always expected to be unitary at the end of compression stroke. The stoichiometric air-fuel ratio of the natural gas composition used is 15.46.
• The Homogeneity Index (HI), which accounts for local distribution of the fuel (=1 in case of ideal homogeneous distribution)
The evolution of HI for the “1300 rpm-2 bar” case is reported in Figure 23Fehler! Verweisquelle konnte nicht gefunden werden.: the air-fuel homogeneity gradually increases during the injection phase, almost reaching a unitary value at the end of the compression stroke and this trend is consistent with what was observed in previous works [21]
ICPC 2019 – 2.3
49
Figure 23 HI evolution for “1300rpm-2bar”: (a) SOI=424 deg, (b) SOI=444 deg [19]
Figure 23 also demonstrates that there is very little difference between the two different SOI, even though the case with earlier SOI shows a slightly higher HI at the end of the compression stroke, because of the longer time available for mixing.
Figure 24 shows the probability mass function (PMF) of Lambda, calculated for the “Late Miller” case at 720 deg CA: as expected for a stoichiometric condition, most of the mixture is characterized by a lambda value close to one, thus ensuring a stable combustion process even in full load.
Figure 24 In-cylinder lambda distribution at 720 deg CA; full load, “Late Miller” profile [19]
Figure 25 Distribution of in-cylinder equivalence ratio during the compression stroke; full load, “Late Miller” profile [19].
Finally, Figure 25 reports the distribution of in-cylinder equivalence ratio (i.e. 1/ lambda) for the full load simulation with “Late Miller” profile on two orthogonal planes during the compression stroke. An almost homogeneous mixture (equivalence ratio equal to 1) is found close to the ignition location, thus increasing the efficiency of the ignition process, though it is possible to discriminate lean zones, close to the cylinder liner, and rich zones close to the piston: the first ones might lead to HC formation while the second ones can lead to CO generation. However, the computed high levels of in-cylinder turbulence are expected to enhance the mixing during combustion
SINGLE-CYLINDER ENGINE TESTING
The single cylinder research engine was operated on an AVL test bed in Graz, Austria where the evaluation of different camshaft profiles, injector configurations, cooled EGR and the combustion chamber itself was performed.
The main advantages of single cylinder engines are lower costs for prototype hardware and lower assembly time for hardware change on the test bed. Since single cylinder engines are externally charged, they provide a degree of freedom in setting the operation points, like boost pressure and exhaust back pressure.
For the investigation of the stoichiometric concept, it brought the following particular benefits:
• Operation with rapid prototype engine control unit possible
• One instead of six cylinders brings a cost reduction, since fewer cost-intensive prototype parts are necessary
• Drift or malfunction on prototype parts are relatively easy to detect
• The operation of the engine is independent from turbocharger hardware (freedom in boost pressure and EGR rate). This gives more liberty to investigate combustion parameters and its sensitivity to them
• Parameters can be investigated independently. Lambda independent from gas exchange work, independent from MFB50.
Characteristics of the single cylinder research engine, based on the HDGAS engine (Figure 26) are:
• Bore x Stroke=135 x 150 mm
• Swept volume= 2.1 dm3
ICPC 2019 – 2.3
50
• AVL Rapid Prototype Engine Management System for closed loop AFR control
• Gas injector designed for high injection pressure
• Cylinder head for single cylinder operation with innovative charge motion
• Boost pressure control by an external supply
• Back pressure control by an electrically-actuated back pressure valve
Figure 26 AVL SCE, based on the HDGAS engine [22]
Potential of cooled EGR
MFB50-EGR variations on a single cylinder engine can show whether desired EGR rates can be applied for multi-cylinder engine applications. The maximum EGR rate is usually limited by misfire, HC emissions or instability in combustion (COV).
Figure 27 shows the influence of MFB50 and EGR rate on brake thermal efficiency, delta pressure over the engine, CH4 emissions and COV for the partial load point (1200 rpm-8 bar BMEP).
Figure 27 Influence of EGR on different parameters in partial load [22]
Figure 28 shows ignition timing variations for different EGR rates in partial load conditions: increase in the EGR rate leads to increase in brake thermal efficiency of the engine. For a constant lambda set point, more EGR reduces CO emission while CH4 increases.
Figure 28 Influence of EGR on different parameters in partial load [22]
Figure 28 also shows that combustion duration (measured as A_I90 minus A_I10) increases with the percentage of EGR. And cycle to cycle variation increases too while the rate of heat release is stretched (Figure 29 and Figure 30): nonetheless, these negative effects are outweighed by the positive ones: reduced wall-heat losses and reduced scavenging work. Furthermore, in full load conditions EGR can help reduce knocking, allowing advanced spark timing and improving fuel efficiency.
ICPC 2019 – 2.3
51
Figure 29 In-cylinder pressure and rate of heat release for different EGR rates in partial load (average cycle) [22]
Figure 30 In-cylinder pressure and rate of heat release for different EGR rates in partial load [22]
Investigations of alternative camshaft profiles
As we have seen, three different intake valve camshafts were foreseen during the SCE test campaign. A volumetric efficiency optimized intake valve timing, which was basically a carry-over from the standard diesel application, as well as two Miller camshafts: the design target for both Miller timings was the same volumetric efficiency at low engine revs, in order to guarantee the same low-end torque (Figure 15).
Figure 31 shows in-cylinder pressure and rate of heat release from SCE operation for the three different camshafts.
Indeed, combustion with the “Early Miller” profile results in a significantly slower turbulent flame velocity and therefore longer heat release. Important for this comparison: all different valve lift curves were evaluated using the same intake port design.
Figure 31 In-cylinder pressure and rate of heat release for different intake profiles in full torque (average cycle)
On the SCE, the effects of the different evolution of turbulence highlighted by CFD (Figure 22Fehler! Verweisquelle konnte nicht gefunden werden.) are clearly visible on the combustion process and offset the thermodynamic advantages shown by 1D analysis which, due to its intrinsic limitation, is not able to capture the flow evolution in the combustion chamber.
All in all, the thermodynamic benefit of a late IVC can be utilized without major changes of the combustion concept. Achieving similar thermodynamic benefits with an early IVC requires a careful adaptation of charge motion to avoid disadvantages in the combustion process.
MULTI-CYLINDER ENGINE TESTING
The multi-cylinder prototype engine was assembled in proto workshop in the FPT’s plant in Bourbon Lancy (France) and it was then delivered to FPT’s testing facilities in Foggia (Italy), where it was installed on a dynamic test bench.
A complete overhaul of the control system had been going on in parallel to the design and assembly of the prototype, due to the new content of the engine. The new injection and ignition systems, the VVT and the EGR valve, all required modification to the existing control system: a new HW ECU was necessary to manage the new components and an auxiliary Smart Driver Unit was introduced to control the injectors, which needed 65V to operate correctly. From the SW point of view, new control strategies were created.
Experimental set-up
The HDGAS engine was installed on a dynamic test bench, able to simulate also motoring conditions, featuring a 450 kW/3500 Nm dynamometer.
ICPC 2019 – 2.3
52
This test bed is normally used for development purposes and it is certified according to Accredia; it is equipped with the following instrumentation:
• ABB sensyflow FMT700-P to measure air flow
• Micro motion CMF025 to measure fuel flow
• AVL AMAi60SII-R2C-EGR analyser to measure CO, THC, O2, CH4, CO2
• AVL LDD analyser to measure NO, N2O, H2O, NH3
• AVL 489 to measure PN
• AVL Indimodul for in-cylinder pressure (6 channels)
• Eurins AdaMo control system to manage the test bench.
Following FPT’s best practice, prior to the proto assembly, the cylinder head was machined to install one pressure sensor in each cylinder, to monitor the combustion process, and a total of 8 thermocouples, to keep the thermal condition of the head under control: moreover, upon the installation on test bench, the whole engine was instrumented in order to completely monitor the various parameters during the testing.
Engine testing
The first operation performed on the engine was the debug of the new components and systems as well as the control system, both HW and SW and, once this operation was successfully completed, the engine was run-in.
Following this, it was possible to test the maximum performance of the engine. The goal of the project was to improve by 10% power and torque compared to the 2013 state-of-the-art NG engines which translated in 2200 Nm and 370 kW, target that was reached, as it is shown in Figure 32.
Figure 32 HDGAS performance, target vs. actual
As mentioned in the CFD section, calculations showed that, with the “Early Miller” profile, turbulence is less favourable, compared to the “Standard” profile, thus worsening engine’s performance: this was confirmed during the tests with the SCE, even though the difference was not so huge.
It was decided to test the “Early Miller” profile also on the MCE, to further verify the results of CFD and SCE: as Figure 33 shows, fuel consumption with “Standard” profile is significantly better than fuel consumption with “Early Miller” profile (“Hard Miller” in the figure), with an improvement of around 4% all over the full load curve (area A). It was therefore decided to continue testing using the “Standard” profile only.
Figure 33 also shows the fuel consumption curve for the “Standard” profile with the addition of EGR: in this case, fuel consumption is further reduced, as predicted by 1D simulations and confirmed by SCE testing (Area B). On the overall, the best configuration (“Standard” profile with EGR) gives an advantage in fuel consumption ranging between 5 and 8% on the full load curve if compared to “Early Miller” profile without EGR.
Figure 33 Fuel consumption in different engine configurations
The optimization process of the engine in steady state conditions followed: this process is aimed at finding the combination of the various factors that affect the engine's performance (ignition timing, injection phasing, air control through throttle valve and WG, EGR valve opening) in order to identify the conditions that enable to achieve the optimum in terms of fuel consumption, combustion stability, margin vs. knock and emissions.
The analysis was conducted over the same four operative points tested by AVL on the SCE:
• Operating Point 1 (1200 rpm-8 bar BMEP)
• Operating Point 2 (1000 rpm-2200 Nm)
700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000Engine speed [rpm]
Torq
ue [N
m]
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
Actual
Target
ICPC 2019 – 2.3
53
• Operating Point 3 (1200 rpm-2200 Nm)
• Operating Point 4 (1900 rpm-370 kW) The experiment was designed to check, at first, the effect of each single innovative technology, then the combined effects of the various technologies employed.
First of all, EOI sweep was performed. The use of Direct Injection involves restrictions on the injection phase, namely:
• Injection must start after EVC, to avoid fuel short circuit to the exhaust
• Injection may not be delayed indefinitely, to prevent subsonic flow through the injector.
The consequence of these constraints is a limitation in the maximum duration of injection.
Retarding EOI leads to a faster combustion, as reported in which shows how MBF50 is anticipated with delayed EOI.
Figure 34 MBF 50 (average over 6 cylinders) vs. EOI
Then, with the optimum EOI, spark advance sweep was carried out: starting from very retarded spark timing (IMEP covariance around 6), spark timing was advanced to reach the Knock Limiting Spark Advance (KLSA). Finally, sweeps of the Corona system parameters (first ignition voltage and then duration) was performed. Figure 35 shows the effect of the spark sweep on fuel consumption at Operating Point 1 with minimum BSFC reached at 8 deg CA after TDC.
Figure 35 Spark timing effect on BSFC, Operating Point 1
Engine optimization led to excellent BSFC values in the whole map, with efficiency exceeding 40% in various operating conditions.
At the end of the project, the engine was capable of performing a complete WHTC, in order demonstrate a 10% CO2 reduction on hot WHTC vs. 2013 state-of-the-art engine: the engine reached a 12% reduction in CO2 emission, therefore exceeding the target. Compared to a more up-to-date gas engine as the Cursor13 NG, the HDGAS engine showed a 4% improvement in fuel consumption over the same WHTC.
CONCLUSIONS
Natural gas engines can help reach the target for CO2 reduction, especially when used with bio-methane; moreover, they are readily available and their diffusion is growing, mainly in long haul missions.
In order to improve the thermal efficiency of gas engines (and, thus, further reduce GHG emissions), FPT joined the HDGAS project, to design and test an innovative engine, specifically conceived to work witn natural gas, and incorporating several advanced features, many of which used for the first time on an HD engine.
Working in close cooperation with other Partners (AVL, Politecnico di Milano and TUG), the task was accomplished employing advanced state-of-the-art 1D and CFD calculations to complement the design, and SCE testing to confirm calculation results: the outcome is an engine which reached the project’s targets, showing a significant reduction in fuel consumption compared to the best natural gas engine currently available.
ICPC 2019 – 2.3
54
ACKNOWLEDGMENTS
The Authors would like to thank the other Partners of WP4 of the HDGAS project for their support.
The research leading to these results received funding from the European Community’s Horizon 2020 Program under grant agreement 653391 (HDGAS PROJECT).
REFERENCES
[1] Ellingsen, L. A-W., Hung, C. R., Research for TRAN Committee – Resources, energy, and lifecycle greenhouse gas emission aspects of electric vehicles, European Parliament, Policy Department for Structural and Cohesion Policies, Brussels, 2018, doi: 10.2861/944056 – Internet http://bit.ly/2HDKk0y
[2] IEA (International Energy Agency), The Future of Trucks: Implications for energy and the environment, 2017
[3] Möhring L., Andersen J.: “CNG Mobility – Scalable, Affordable and Readily Available Solution for Environmental and Climate Challenges”, 38th Internationales Wiener Motorensymposium, Wien, 2017
[4] RICARDO, Impact Analysis of Mass EV Adoption and Low Carbon Intensity Fuels Scenarios, report on behalf of CONCAWE, 2108
[5] https://ec.europa.eu/eurostat/statistics-explained/index.php/Electricity_generation_statistics_%E2%80%93_first_results
[6] CARB (California Environmental Protection Agency Air Resource Board), Joint agency staff report on Assembly Bill 8: 2016 assessment of time and cost needed to attain 100 hydrogen refueling stations in California, 2017 – Internet https://www.energy.ca.gov/2017publications/CEC-600-2017-002/CEC-600-2017-002.pdf
[7] https://www.acea.be/press-releases/article/truck-co2-targets-no-public-charging-points-for-electric-or-hydrogen-trucks
[8] Semin R., “A Technical Review of Compressed Natural Gas as an Alternative Fuel for Internal Combustion Engines”, American J. of Engineering and Applied Sciences 1 (4): 302-311, 2008
[9] Schuller O. et al., Greenhouse Gas Intensity of Natural Gas, Thinkstep report on behalf of NGVA Europe, 2017
[10] http://www.ansa.it/canale_motori/notizie/eco_mobilita/2018/10/25/iveco-stralis-a-metano-da-record-1.728-km-con-un-pieno_1217b6ee-8fcd-4087-8804-ac31f3f3cfd2.html
[11] Krähenbühl P. et al., “FPT Industrial’s Leadership in Natural Gas Technologies for Industrial Engines”, 38th Internationales Wiener Motorensymposium, Wien, 2017
[12] Heywood J. B., Internal Combustion Engine Fundamentals, McGraw Hill Inc., New York, 1988
[13] Fasching P., Natural Gas as Fuel for Monovalent and Dual Fuel Combustion Engines - an Experimental and Numerical Study, Ph.D. thesis, Technische Universität Graz, Graz, 2017
[14] Figer, G et al., "Nutzfahrzeug-Gasmotoren mit Dieseleffizienz", MTZ – Motortechnische Zeitschrift, 75, (10), 2014, doi:10.1007/s35146-014-0573-4
[15] Geiger, J. et al., "Der Erdgasmotor als Nutzfahrzeugantrieb – Trends und Herausforderungen bei der Entwicklung", 8th Conference on Gas-Powered Vehicles, Stuttgart, 2013
[16] Lucchini T. et al., "Multi-dimensional modelling of the air/fuel mixture formation process in a PFI engine for motorcycle applications," SAE Technical Paper 2009-24-0015, 2009, doi: 10.4271/2009-240015
[17] Montanaro A. et al., "Experimental Characterization of High-Pressure Impinging Sprays for CFD Modelling of GDI Engines," SAE Int. J. Engines 4 (1):747-763, 2011, doi: 10.4271/2011-01-0685
[18] Lucchini T. et al., "Automatic Mesh Generation for CFD Simulations of Direct-Injection Engines," SAE Technical Paper 2015-01-0376, 2015, doi: 10.4271/2015-01-0376
[19] Paredi D. et al., "Gas Exchange and Injection Modelling of an Advanced Natural Gas Engine for Heavy Duty Applications," SAE Technical Paper 2017-24-0026, 2017, doi: 10.4271/2017-24-0026
[20] Scarcelli R. et al., “CFD and optical investigations of fluid dynamics and mixture formation in a DI-H2 ICE” ASME, ICEF2010-35084, 2010
[21] Lucchini T. et al., "Full-Cycle CFD Modelling of Air/Fuel Mixing Process in an Optically Accessible GDI Engine," SAE Int. J. Engines 6(3):1610-1625, 2013, doi: 10.4271/2013-24-0024
[22] Golini S. et al., “Natural Gas Engines for Long-Haulage Applications: Current Approach and Future Developments”, 16th Conference: The Working Process of the Internal Combustion Engine, Graz, 2017
ICPC 2019 – 2.3
55
DEFINITIONS, ACRONYMS, ABBREVIATIONS
AFR Air/Fuel Ratio
ATS After-Treatment System
BDC Bottom Dead Centre
BEV Battery Electtric Vehicle
BMEP Brake Mean Effective Pressure
CA Crank Angle
CFD Computational Fluid Dynamics
CNG Compressed Natural Gas
DI Direct Injection
EGR Exhaust Gas Recirculation
EOI End Of Injection
EU European Union
FEA Finite Element Analysis
FC Fuel Cells
FCV Fuel Cells Vehicle
GHG Greenhouse Gas
HC Unburned Hydrocarbons
HD Heavy Duty
HDV Heavy Duty Vehicle
HI Homogeneity Index
HVA Hydraulic Valve-lash Adjustement
ICE Internal Combustion Engine
IMEP Indicated Mean Effective Pressure
IVC Intake Valve Closing
KLSA Knock Limiting Spark Advance
LCV Light Commercial Vehicles
LH Long Haul
LNG Liquefied Natural Gas
NG Natural Gas
MFB Mass Fraction Burned
MCE Multi-Cylinder Engine
SCE Single-Cylinder Engine
SOI Start Of Injection
TDC Top Dead Centre
TKE Turbulent Kinetic Energy
TR Tumble Ratio
WG Wate Gate
WHTC World Harmonised Transient Cycle
56
ICPC 2019 – 2.4
Potentials for friction reduction with commercial vehicle engines – Contribution of the power cell unit
Dr.-Ing. Andreas Pfeifer
Mahle GmbH
M.Sc.Tobias Funk, Dr.-Ing. Thomas Deuß, Dipl.-Ing. Holger Ehnis
Mahle International GmbH
Copyright © 2019 AVL List GmbH, Mahle GmbH and SAE International
ABSTRACT
The reduction of friction losses in combustion engines is of great significance for lowering fuel consumption and CO2 emissions. Extensive parameter studies of diesel and gasoline engines for passenger cars have demonstrated that the piston group has significant potential for reducing friction. There are currently no statutory limits on CO2 emissions for commercial vehicle engines, but in the future, however, there will be strict limits in place for these types of engines as well. Friction reduction also plays a critical role for the end customer in the commercial vehicle sector, as fuel consumption makes up a significant proportion of the total cost of ownership (TCO). For these reasons, an additional friction power test bench has been set up at MAHLE to perform measurements on fired commercial vehicle engines.
This article presents the test bench setup, measurement and evaluation methods, and the established measurement accuracy. The influence of piston installation clearance, piston profile, and piston skirt surface structure on friction losses are assessed. Additionally, an optimized variant consisting of a combination of several individual parameters is investigated to evaluate the overall potential for reducing friction. To determine the savings in fuel consumption and CO2 emissions for each variant, a driving cycle simulation is performed. The resulting savings in CO2 emissions are up to 5 gCO2/km.
INTRODUCTION
Statutory limits for the CO2 emissions of passenger cars have been in place for a long time now and are continuously being made stricter. Statutory limits on CO2 emissions are now going to be introduced for heavy-duty commercial vehicles in the EU as well. An
expected reduction of 20%, relative to emissions from 2019, is planned by 2025. A further 15% reduction is scheduled by 2030. To achieve these objectives, the reduction of friction inside the engine is highly significant. With the goal of determining friction losses under real conditions, that is, fired operating conditions, MAHLE set up a friction power test bench for passenger car engines over ten years ago. In extensive individual parameter studies on passenger car diesel engines and gasoline engines, with a total of over one hundred test variants, significant potential for improvement was shown.
Another friction power test bench has now been set up for commercial vehicle engines so that potential savings can be determined by means of a systematic parameter study for the commercial vehicle sector as well.
MEASUREMENT METHOD FOR DETERMINING FRICTION LOSSES IN THE COMMERCIAL VEHICLE ENGINE
Test bench setup
Friction losses are calculated using the indication method. The indicated mean effective pressure IMEP is determined by means of high-pressure indication. The brake mean effective pressure BMEP can be calculated from a torque measurement. The friction mean effective pressure FMEP being sought is the difference between the indicated and brake mean effective pressure. In order to achieve the high level of measurement accuracy required for the indication method, external conditioning systems are used both for the coolant and for the engine oil. The friction power test bench is also equipped with conditioning systems for ambient air, intake air and fuel. A detailed description of the test setup and measurement equipment can be found in [1].
ICPC 2019 – 2.4
57
Measurement and evaluation method
To evaluate the saving potentials of individual parameters for the piston group, friction measurements are performed under steady-state conditions across the entire operating map. Design of experiments (DoE) is used to determine the FMEP maps. Using 21 operating points that vary the parameters of load, engine speed, and engine temperature, a FMEP map is established for the entire operating range of the engine. Three such operating map measurements are performed for each variant. The FMEP map for a variant is the average of these three measurements (Figure 1, left). The influence of such a design variant on engine friction is depicted in the form of a FMEP difference map (Figure 1, right). To obtain this, one of the FMEP maps for the variants to be compared is subtracted from the other. This difference map can be used to draw conclusions about friction behavior across the entire operating map.
Figure 1 Generation of difference map: FMEP maps of two variants to be compared (left), and the resulting FMEP difference map (right)
Measurement accuracy
For the indication method, very high measurement accuracy is critical to resolve the very small differences between the indicated and brake mean effective pressure. Therefore, extensive investigations of measurement accuracy are performed prior to the actual parameter study. They cover repeatability, reproducibility, and the influence of engine assembly on measurement accuracy.
The results for the 21 operating points from the FMEP map are used to evaluate individual measurement accuracies. To evaluate repeatability, the standard deviation of the FMEP is calculated from ten successive individual measurements. The average results in repeatability of ±0.002 bar for the FMEP (Figure 2).
The reproducibility is also evaluated on the basis of the standard deviation for the FMEP. In contrast to repeatability, operating map measurements from
three successive days are used. The average from the evaluation of the standard deviations results in reproducibility of ±0.01 bar for the FMEP.
It is typically necessary to assemble an engine, to be able to compare different design variants. To evaluate measurement accuracy, the influence of engine assembly on FMEP must therefore be investigated. To this end, the engine is fully disassembled and reassembled several times using the identical components and friction power measurements are taken in between each disassembly and reassembly. The average standard deviation for FMEP is ±0.02 bar, which is designated the confidence limit.
The FMEP differences must be outside of the confidence limit in order to unambiguously attribute the result to the design change. If the FMEP differences are below the confidence limit, then additional evaluations must be performed in order to be able to draw conclusions at least about tendencies. A detailed description of these tests can be found in [1].
Figure 2 Measurement accuracy of FMEP measurements: repeatability, reproducibility, and influence of engine assembly
RESULTS OBTAINED FROM THE COMMERCIAL VEHICLE ENGINE
In a systematic parameter study, the influence of individual piston group design parameters on friction was investigated. Table 1 shows all of the parameters that have been varied for the commercial vehicle engine. In over 30 tests, the influence of different design parameters including the tangential force of the oil control ring, the piston type, and the geometry of the connecting rod small end have been examined [2]. The results for the parameters of piston installation clearance, piston profile, and piston skirt surface structure are presented below.
ICPC 2019 – 2.4
58
Table 1: Parameters investigated for commercial vehicle engine
Piston installation clearance
Investigations on the passenger car diesel engine with aluminum pistons have shown that piston installation clearance can have significant potential for reducing friction [3]. Based on these findings, four different installation clearances are investigated for the commercial vehicle engine with steel pistons. The baseline variant has an installation clearance of 63 µm, measured on the skirt coating after the test run. One variant with installation clearance reduced to 31 µm and two variants with increased clearances of 85 µm and 107 µm are tested. The corresponding FMEP difference maps are shown in Figure 3. It is evident that variation of installation clearance leads to only minor differences in FMEP. No distinct dependence on load or engine speed is observed. The results are very close to the confidence limit, but nevertheless the three difference maps show that reducing installation clearance tends to cause greater friction with steel pistons as well.
The reason for this fundamentally small influence of the installation clearance is presumably the very similar material properties of the cylinder liner and the piston. In contrast to many passenger car diesel engines with aluminum pistons, the commercial vehicle engine has steel pistons that are installed in so-called wet cylinder liners. The piston and liner therefore have similar thermal expansion coefficients. This means that even under full load conditions, there can presumably be no interference between the piston skirt and the cylinder wall. Even pistons with small installation clearance still have sufficient operating clearance in the warm state and thus have only a slight disadvantage in terms of friction losses.
Figure 3 FMEP difference maps, measured during operation with various piston installation clearances (top: 63 µm – 31 µm; center: 63 µm – 85 µm; bottom: 63 µm – 107 µm), engine temperature 100 °C
Piston group component Parameter
Installation clearance
Pin offset
Piston profile
Skirt roughness
Skirt coating
Skirt area
Pin bore geometry
Piston type
Tangential force of oil control ring
Top ring height
Pin Pin coating
Other Oil viscosity
Piston
Rings
ICPC 2019 – 2.4
59
Piston profile
The piston profile can affect the build-up of the lubricating film on the piston skirt. Starting with a conventional, barrel-shaped, oval piston profile, three more different profiles are investigated. These alternative piston profiles are designed with the goal of influencing lubricating oil distribution on the piston skirt such that hydrodynamic lubrication conditions prevail to a greater extent. The tested piston profiles are shown in schematic form in Figure 4.
Figure 5 indicates the corresponding FMEP difference maps. The Camel Back 1 piston profile, with pronounced horizontal humps, shows significant benefits in FMEP over the entire operating map (Figure 5, top). No dependence on engine speed is evident, although there is a clear dependence on load. The greatest advantages in FMEP are evident at higher loads across the entire speed range. The maximum savings in FMEP are 0.09 bar.
The Camel Back 2 piston profile, with more substantial humps, shows similar friction behavior to the Camel Back 1 (Figure 5, center). No significant dependence on engine speed is evident. The evident dependence on load, however, is less pronounced than for the Camel Back 1 profile. The potential savings in FMEP are also somewhat lower at about 0.05 bar.
The friction behavior of the Banana Shape piston profile, with the humps curved like a banana, is largely the same as that of the Camel Back 2 (Figure 5, bottom). No benefit in FMEP is evident in the low to medium load range. The maximum FMEP benefit is also 0.05 bar.
The mixed lubrication component of piston skirt friction increases as the load increases, because greater lateral forces arise under these operating conditions and the thermal expansion of the components increases, especially that of the piston. The thermal expansion increases the contact pressure between the piston and cylinder wall. When the piston profile improves the lubricating oil distribution on the piston skirt, this promotes hydrodynamic lubrication conditions and the mixed lubrication component decreases. For all of the investigated piston profiles, therefore, the greatest friction advantage is seen at high loads. The Camel Back 1 piston profile is the optimization with the greatest friction advantage.
Figure 4 Schematic description of the examined piston profiles
ICPC 2019 – 2.4
60
Figure 5 FMEP difference maps, measured during operation with different piston profiles (top: Camel Back 1; center: Camel Back 2; bottom: Banana Shape), engine temperature 100 °C
Piston skirt surface structure
To investigate the influence of surface structure on friction, two different piston skirt surface profiles are compared. Sketches of the two surfaces are shown in Figure 6. The base variant is the conventional series production design of the skirt surface. The modified surface structure is characterized by distinct longitudinal waviness. Thus small plateaus form after test run whereby the effective running surface is reduced in comparison to the conventional piston skirt surface structure.
Figure 6 Schematic description of the examined piston skirt surface structures after test run
The FMEP difference map in Figure 7 shows the influence of the modified piston skirt surface structure on FMEP. Small friction advantages are evident in the low to medium load range. As the load increases, however, friction disadvantages appear for the modified, rough surface structure. These disadvantages are especially pronounced at low engine speeds and high loads. This operating range is characterized both by increased component temperatures and therefore reduced operating clearance and by high lateral forces. This results in high surface pressures for the modified surface structure. The mixed lubrication component consequently increases.
ICPC 2019 – 2.4
61
Figure 7 FMEP difference map, measured during operation with different piston skirt surface profiles (conventional - modified piston skirt surface structure), engine temperature 100 °C
POTENTIAL FOR CO2 REDUCTION
In addition to the potential savings in FMEP, great interest lies in the determination of the associated fuel consumption savings and reduction in CO2 emissions. The measured FMEP maps, together with the corresponding vehicle data, are used as input parameters for a driving cycle simulation. Three different driving cycles (Long Haul Vecto, HHDDT transient, HHDDT cruise) are considered, with three different vehicle load cases for each (empty, reference, full). This results in nine individual values for evaluating friction-based fuel consumption savings and reductions in CO2 emissions. The influence of the dynamic friction behavior on the cumulative fuel consumption and CO2 emissions in driving cycles is considered in [4].
Fuel costs represent a large portion of the total cost of ownership (TCO) in the commercial vehicle sector. Figure 8 shows the percentage of fuel savings and associated potential annual cost savings for the example of the Camel Back 1 piston profile results. The cost estimate is based on annual mileage of 150,000 km and average fuel consumption of 34 L/100 km. A price for diesel of EUR 1.20 per liter was assumed. The resulting cost savings are between EUR 100 and EUR 350 per year, depending on the driving cycle and load state considered.
Figure 8 Fuel consumption savings and TCO savings from the parameter Camel Back 1 piston profile
The average values for potential savings in CO2 emissions for the investigated parameters are shown in Figure 9. The parameter piston installation clearance has potential savings of up to 2.5 gCO2/km. By optimizing the piston profile, CO2 emissions can be reduced by up to 3 gCO2/km, while a suitable selection of the surface profile on the piston skirt has a maximum potential of 1.3 gCO2/km. The findings of the previous individual parameter studies are incorporated into a so-called best of variant. The combination of various design parameters enables CO2 emissions savings of about 5 gCO2/km.
Figure 9 Fuel consumption savings and CO2
emissions reduction due to reduced friction (values are averages from three driving cycles (Long Haul VECTO, HHDDT transient, HHDDT cruise) with three load cases for each (empty, reference, full))
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0
50
100
150
200
250
300
350
400
Fu
el C
on
su
mp
tio
n S
avin
gs [
%]
TC
O s
avin
gs [
€/y
ear]
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
CO
2E
mis
sio
n S
avin
g [
g/k
m]
Best
of
Pis
ton
Desig
n P
ara
mete
rs
Pis
ton
Pro
file
Conventional -
Cam
el B
ack 1
Pis
ton
In
sta
llati
on
Cle
ara
nce
31 µ
m -
107 µ
m
Pis
ton
In
sta
llati
on
Cle
ara
nce
63 µ
m -
107 µ
m
Pis
ton
In
sta
llati
on
Cle
ara
nce
63 µ
m -
85 µ
m
Pis
ton
In
sta
llati
on
Cle
ara
nce
63 µ
m -
31 µ
m
Pis
ton
Skir
t S
urf
ace S
tru
ctu
reC
onventional -
Modifie
d
Pis
ton
Pro
file
Conventional -
Cam
el B
ack 2
Pis
ton
Pro
file
Conventional -
Bana
na S
hap
e
ICPC 2019 – 2.4
62
CONCLUSION
The measurement and evaluation procedure that has been used for friction power measurements on passenger car engines was successfully transferred to the commercial vehicle engine. A high measurement accuracy of ±0.02 bar FMEP is possible for the engine used. As part of a systematic individual parameter study, the parameters piston installation clearance, piston profile, and piston skirt surface structure have already been investigated. Further tests will determine the influence on friction of the parameters structural stiffness, ovality, skirt surface, and coatings. With the findings to date, CO2 emissions can be reduced by up to 5 g/km.
REFERENCES
[1] Deuß, T.; Ehnis, H.; Schulze Temming, R.; Künzel, R.: Friction power measurements with a fired HDD engine—method and initial results. 17th Stuttgart International Symposium on Automotive and Engine Technology, 2017.
[2] Deuß, T.; Ehnis, H.; Schulze Temming, R.; Künzel, R.: Friction power measurements with a fired commercial vehicle engine—piston group potentials. MTZ Motortechnische Zeitschrift. 02/2019, Volume 80.
[3] Deuß, T.; Ehnis, H.; Freier, R.; Künzel, R.: Friction power measurements of a fired diesel engine—piston group potentials. MTZ Motortechnische Zeitschrift. 05/2010, Volume 71.
[4] Funk, T.; Ehnis, H.; Künzel, R.; Bargende, M.: Dynamic friction behavior of a gasoline engine in transient operation. 19th Stuttgart International Symposium on Automotive and Engine Technology, 2019.
63
ICPC 2019 – 2.5
ICE optimized for off-road hybrid powertrain
Dr. - Ing. Markus Schwaderlapp, Dr.-Ing. Paul Grzeschik
DEUTZ AG
Copyright © 2019 AVL List GmbH, DEUTZ AG and SAE International
ABSTRACT
This paper covers the DEUTZ strategy towards CO2 free powertrains. The discussion is focused on hybrid powertrains and on an optimized engine layout for these applications: reduction of complexity can result in downsizing by reducing the cylinder number or adjusting the technological level of the engine. The additional low-end torque provided by the electric motor also provides the opportunity to replace a Diesel engine by a cost-effective gas engine. In this context, the goal is always to make use of the already existing DEUTZ portfolio to maximize the commercial competitiveness of hybrid applications.
INTRODUCTION
The off-road powertrain is a domain of the internal combustion engine, see Figure 1: it combines in an almost ideal manner compactness, high operation range and robustness. With Stage V the pollutant emissions are reduced to a minimum contributing to a clean environment.
Figure 1 Application examples for DEUTZ engines
However, even with highly efficient Diesel engines, CO2 minimization remains a challenge. There are two complementary roadmaps to convert an almost emission free powertrain into a CO2 free powertrain,
see Figure 2: regenerative fuels and electrification. DEUTZ is very active in following both roadmaps.
Figure 2 Approaches towards a CO2 neutral drivetrain
Electrification means full electric drives for smaller vehicles and hybrid solutions for higher demands of power and operating range. Combining an engine with a 48 V electric motor (“mild hybrid”) or a 360 V motor (“full hybrid”) saves fuel (CO2) and has the advantage of an improved transient response. For the combustion engine, hybrid applications create the potential for component simplification and reduction of engine complexity.
In the end, the technical solution must create a benefit for the end customer – either by reducing the total cost of ownership or by creating advantages for the application of the vehicle, such as local zero emission or low noise in electrical drive mode. The hybrid solutions currently under development at DEUTZ offer those new potentials for the customer.
HYBRID POWERTRAINS FOR NRMM
One of the characteristics of NRMM powertrains is the wide variety of applications and operation profiles, see Figure 3. The technological and economic potential for electrification of these powertrains is strongly dependent on factors like dynamics of
ICPC 2019 – 2.5
64
operation, power and energy demand, supply infrastructure availability, powertrain on/off ratio and others.
Figure 3 Typical engine operation profiles for different NRMM applications
Figure 4 Hybridization potential for different energy demand and operating range regimes
ICPC 2019 – 2.5
65
Looking to the different applications, Figure 4 shows how the degree of electrification depends on the energy demand and the available energy supply infrastructure, which is equivalent to the necessary operating range of the respective application.
Machines with low cycle energy demand, which at same time do not have to travel too far away from re-charging infrastructure, are most conveniently equipped with a fully electric powertrain. They do not require large, sophisticated and therefore high-cost energy storage capabilities. For applications such as indoor lift trucks, light to medium-duty fork lifts, or airport towing tractors, a strong trend towards full electrification has already set in in the past years, and with the further optimization of electric powertrains, it can be expected that these applications will remain a domain of electric drives.
On the other end of the energy demand vs. operating range field, we have applications such as agricultural tractors which typically operate far from any high-performance re-charging infrastructure. This is combined with a very high demand for both power and energy to fulfill the task. For a day of e.g. ploughing duty, a tractor requires the energy equivalent of approx. 600 L of Diesel fuel. To accommodate this amount of energy in a chemical storage device, a battery module with a volume of approx. 3500 L and a mass of around 10 t would be necessary [1]. With the current technology
background, it will not be economically and practically feasible to electrify these applications in the foreseeable future, although several approaches to do so exist in pre-develompment and prototype status.
In between these boundary cases, there is an intermediate area where a combination of electrical and conventional (i.e. ICE based) drivetrains is becoming more and more attractive as technology levels – especially those of the energy storage device – progress. A large number of different applications such as heavy-duty lift trucks, wheel loaders, telehandlers and, to some extent, excavators, fall into this category.
Figure 5 shows the sub-systems of a typical 48 V hybridized powertrain for a telehandler application as developed by DEUTZ in the E-DEUTZ program. It is clear that such a powertrain raises a number of questions and challenges which are very new for both manufacturers and operators of NRMM; such as the location, or distribution, of the energy storage, the packaging space for electrical and electronical equipment, the requirement for a low temperature cooling system, the modified weight distribution of the vehicle, personal safety considerations and so on. Obviously, one of the most important and immediate questions is that for the economical viablilty of a hybridized powertrain.
Figure 5 Typical layout of a hybridized 48 V NRMM powertrain
ICPC 2019 – 2.5
66
As for the shown powertrain, by careful total system layout, the initial costs of electrification can be partially or fully compensated. By downsizing of the combustion engine, the engine-out power drops below the regulatory border of 56 kW and allows for the subsequent elimination of the expensive SCR system. In addition, it can be shown that hybridization of a telehandler as performed by DEUTZ will yield an operating cost saving, depending on the usage cycle, of around 10,000 € during the lifetime of the machine. Nevertheless, the savings margin will not always be high enough to cover all technically reasonable applications. So apart from the cases where the
inherent advantages of a hybrid drivetrain (better dynamics, zero pollutant and noise emission when driving fully electrically) are sufficient to convince owners and operators, the ICE optimized for hybridization has to contribute to the cost-effectiveness of the whole hybrid powertrain.
COMBUSTION ENGINES OPTIMIZED FOR HYBRID POWERTRAINS
To achieve this goal, DEUTZ offers three main approaches to the optimized combustion engine as showin in Figure 6.
Figure 6 Alternatives for hybridized ICE optimization approaches
The choice between the alternatives is mainly dependent on the operation scenario of the NRMM application and the hybrid powertrain operating strategy.
Size Fit
Downsizing is a feasible approach where the bulk of operation load and time share is still provided by the ICE while the electric drive is mainly used to boost for peak performance events. In these cases, as demonstrated by the DEUTZ 48 V hybridized
telehandler, a very convenient approach is so replace a four-cylinder engine (in this case, the DEUTZ TCD 3.6 L 74 kW machine) by a cost-effective three-cylinder engine (DEUTZ TCD 2.2 L 56 kW) and bridge the power gap with an appropriately sized electrical machine. As Figure 7 shows, this substitution additionally improves the total low-end torque of the drivetrain while at the same time shifting the application’s mean load curve into a higher-load, consumption-optimum range of the ICE operation map.
ICE AS RANGE EXTENDER:
TECH FIT
OCCASIONAL USE OF ICE:
GRADE FIT
PEAK LOADS COVERED BY EM:
SIZE FIT
ICPC 2019 – 2.5
67
Figure 7 Telehandler operation map for conventional and hybridized powertrains
Figure 8 Packaging comparison between conventional (TCD 3.6 four-cylinder engine, grey) and hybridized power plant (with TCD 2.2 three-cylinder engine, red)
An additional significant benefit of this specific example is that legislation allows 56 kW engines to go without sophisticated EAT system, thus further
reducing cost and installation space demand. The overlay in Figure 8 gives an impression of the longitudinal size of the respective power plants. While
ICPC 2019 – 2.5
68
keeping the overall length, the hybridized powertrain even leaves some formerly blocked space above the clutch/gearbox assembly.
That space can be used to accommodate some of the necessary electrical equipment or, if the electrics can be placed in a different location, allows for a size reduction of the engine bay – an important issue for the telehandler vehicle design for reasons of visibility towards the right-hand side of the machine.
Grade Fit
The typical NRMM combustion engine is an extremely robust heavy-duty machine designed for a long product life under demanding ambient conditions. Depending on their displacement volumes, DEUTZ engines are certified for B10 life-times of 6,000 to 13,000 hours and even after their “first life”, they can be refurbished for a “second life” as a cost-effective alternative in the DEUTZ XCHANGE program. Major components and systems are regularly found to remain in excellent condition even after long usage. However, in cases where the electrical portion of a hybrid powertrain is designed to be the main power source (e.g. in 360 V full hybrid applications), the ICE does not have to be specified for such long lifetime or heavy duty usage.
Figure 9 Cost optimization potential of a low usage ICE in a hybridized powertrain
The powertrain’s operating strategy would employ the combustion engine only occasionally to either significantly increase overall power output or to cover occasional work scenarios when long-term electrical operation is not feasible. Consequently, individual systems and components may be replaced with lower-grade derivatives to improve the ICE’s cost-
effectivenesse. Figure 9 gives some examples of possible cost optimization potentials on sub-system and component level. This “right-grade” approach proves to be especially effective within the DEUTZ strategy, which traditionally allows for competitive and economically feasible versioning of components even in small yearly quantities. For example, as showin in Figure 10, the replacement of a steel crankshaft by a cast iron crankshaft could be amortized within a yearly production rate of around 13,000 pieces. As soon as demand for these kinds of applications reaches a sufficiently high level, DEUTZ will engage in the described cost optimization.
Figure 10 Break-even calculation for the introduction of a low-cost crankshaft
Tech Fit
Hybridized applications which require even less contribution by the ICE (e.g. those which use the ICE just as a range extender) allow for application of cost-effective, ligher-duty engines such as gas engines, which are offered by DEUTZ in the form of the G2.2 [2]. This engine, designed for LPG and, with an adaptation, to CNG is the first DEUTZ engine for NRMM serving the market for material handling but as well other applications demanding for a robust engine where a Diesel engine with turbocharger and a sophisticated emission control is not the primary option.
The engine, with its main technological features shown in Figure 11, offers a robust approach taking into account economic features as well as a compact design. With a high level of synergies to the diesel engine platform of D/TD/TCD2.2, the installation in the same applications is redundant, providing a maximum torque of 160 Nm and a rated power of 42 kW at 2800 rpm.
DEUTZ is also introducing the G2.9, a four-cylinder variant of the same engine family.It is also planned to extend the gas engine business to higher displacements to achieve ratings of 70 kW and more.
Turbocharger Technology
Cylinder Head Material
Cam Tappets
Piston Material
Piston Cooling System
Conrod Bushing
Crank Shaft Material
Bearing Shells
Oil / Fuel Filters
0 5000 10000 15000 20000
Init
ial I
nve
st
Crankshaft Total Costs
Pieces p.a.
Steel
Cast Iron
ICPC 2019 – 2.5
69
Figure 11 DEUTZ G2.2 technology overview
In this field, DEUTZ has been developing the HoLeGaMo high power gas engine with 150 kW and 800 Nm [3], see Figure 12.
Figure 12 DEUTZ HoLeGaMo high power gas engine
This publicly funded pre-development project is helping to extend the application range for gas engine – and with them that of cost-effective hybridized powertrains – into power ranges of intermediate to heavy machinery.
DEUTZ PORTFOLIO OUTLOOK
In the coming years, the E-DEUTZ approach will gradually address machines and applications with increasing power and energy demands as shown in Figure 13. Starting with ICE powers < 56 kW as seen in today’s telehandler demonstrators, on a 2 … 10 year scale, intermediate tractors and larger equipment such as excavators are in the focus of hybrid power trains developed and offered by DEUTZ.
In parallel, the development of full-electric drives for small to intermediate applications will be continued, expecting to cover full electric small construction and agricultural equipment > 56 kW before the year 2030.
Modified Cylinder head and Crankcase castings
3-way catalyst
Modified Valves
and Valve seats
LPG Mixer
Throttle
Intake air
manifold
Piston (ε = 11):• Optimized piston bowl
geometry• Valve pocket for inlet
valve (Backfire)• Suction pressure at
closed throttle down to 200mbar abs. → oil consumption and reverse blow-by→ U-flex design of oil ring allows adaptation to cylinder surface deformation
• Friction reduced by U-flex ring, reduced ring thickness and reduced ring force
Evaporator• Converting liquid
gas into gaseous form• Reducing system pressure
(high pressure) to low pressure• 1st stage pressure controller (mechanic)
Pressure regulation valve (DEPR)• 2nd stage pressure controller
(electronic)• Regulation of LPG/CNG mass flow• Adjusting air ratio 14.7:1
Lock-Off Valve• Mounted at
the gas tank• Cuts the Gas supply after
ignition-off
ICPC 2019 – 2.5
70
Figure 13 Today’s and future applications for electrified powertrains
CONCLUSION
With the ever-increasing demand for both pollutant emission reduction and CO2 minimization, powertrain electrification has become an important topic for NRMM manufacturers and operators. As fully electric powertrains are not (yet) able to cover the full range of applications, hybrid powertrains are becoming an important step towards CO2 neutral operation of non-road equipment and machinery.
Hybridization, however, has to be accompanied by a strong effort to minimize cost of the conventional components to make electrified powertrains as economically attractive as possible. The “size fit” and “tech fit” approaches are already part of the work scope, while the “grade fit” approach will be subsequently implemented when customer demands increase. With their strong, diversified engine portfolio, DEUTZ is confident to provide the optimum, cost-effective solution for the ICE in any application, environment, and operating strategy.
ACKNOWLEDGMENTS
The HoLeGaMo project has been funded by the German Federal Ministry for Economic Affairs and Energy.
REFERENCES
[1] [1] M. Schwaderlapp, M. Winkler, Th. Adermann, K.-P. Bark: CO2-neutrale Mobilität. Potenziale von alternativen Kraftstoffen und Elektrifizierung bei Off-Highway-Anwendungen. In: MTZ 11/208
[2] [2] H. Bülte, C. Funke, K.-P. Bark, K. Tedsen: DEUTZ G2.2 – The New 3-Cylinder Gas Engine for Nonroad Mobile Machinery. In: Heavy-Duty-, On- and Off-Highway Engines. Future Challenges. 13th International MTZ Conference on Heavy-Duty Engines, Cologne 2018
[3] [3] H. Bülte, G. Töpfer, C. Funke: Gas Engines for Mobile Machinery - A Contribution to the Reduction of CO2 Emissions. In: 6th International Engine Congress, Baden-Baden 2019
DEFINITIONS, ACRONYMS, ABBREVIATIONS
HoLeGaMo High performance gas engine (Hochleistungs-Gasmotor)
ICE Internal combustion engine
LT Low temperature
NRMM Non-road mobile machinery
PMSM Permanent-magnet synchronous motor
2-10 year horizon
2-10 year horizon
Today
Starters & selective replacement of
attachments
Diesel downsizing
for small equipment
<56kW (fork lift
truck, telehandlers,
etc.)
Full replacement of mechanical
attachments (e.g. tractor, etc.)
Diesel downsizing for larger
equipment >56kW (Roller, etc.)
Diesel downsizing for larger
equipment >160kW
Today
Compact equipment and material
handling <37kW
wheelloader, etc.
Small rollers, Forklifts, etc.
Hybrid
Full-Electric
Small construction and
residential equipment <56kW
Lawn, Mowers, etc.
Compact utility tractor, etc.
Small construction and
agricultural equipment >56kW
Telehandler, small tractors,
excavators etc.
71
ICPC 2019 – 3.1
Fuel Cells: A Profitable Zero-Emission Solution for Heavy Duty Trucks
William Resende, Heimo Schreier, Dr. Alexander Schenk, Martin Ackerl
AVL List GmbH
Copyright © 2019 AVL List GmbH and SAE International
ABSTRACT
In this paper, a fuel cell powertrain for HD truck application is evaluated in greater details. The market drivers are discussed, the technical challenges described and solutions from AVL are proposed. Specific focus is given to the adoption of the current fuel cell technology to achieve a profitable zero-emission powertrain for heavy duty trucks.
INTRODUCTION
The trucking industry is facing challenges with regards to powertrain emissions as governments around the world push for stricter regulations, on a country and city level. These regulations are arising from findings and recommendations from several study groups which pin the temperature increases on greenhouse gas emissions. The Paris Agreement was the culmination of those discussions and set clear targets for CO2 reductions across different sectors. To achieve the upcoming CO2 targets, vehicle OEMs need to commercialize alternative powertrain technologies like hybrids as well as battery and fuel cell electric powertrains. Specifically the long-haul application is in the focus, as this vehicle category contributes most to the emissions of the on-road transport sector.
Additionally, city governments have started to propose bans to combustion engine powertrains from urban areas to avoid local air pollution and noise emissions. To cope with this demand battery electric powertrains have been brought to the market for trucks as well as busses. However, one of the remaining challenges of this technology is the limited range as well as the typically longer refilling times.
A technology which has the potential to overcome these challenges is fuel cell technology. During the past years this technology has made significant progress and different OEMs have already been developing and testing it for commercial vehicles.
However, as this technology has been developed mainly for passenger car application in the past, some engineering challenges need to be solved to achieve a sufficiently profitable and durable truck powertrain and hence, achieve a significantly high market penetration to contribute to the necessary emissions reductions in the on-road transport sector.
MARKET DRIVERS
In the trucking business, there are several factors driving the change to low or even zero emission powertrains. Among them, government CO2 regulations, drive bans and tolls.
CO2 Emission Regulations
Over the last years governments have been taking strong instances with regards to greenhouse gas emissions (see Japan, China, Korea, European Union and California). Figure 1 summarizes the current CO2 regulations and fuel economy standards in place in several countries for commercial vehicles.
Figure 1 CO2 and Fuel Economy Regulations in the World today
These regulations are expected to get stricter over the next years as the participation of CO2 emissions from the trucking business will start representing a larger share of the total amount of emissions. This is shown in Figure 2.
ICPC 2019 – 3.1
72
Figure 2 Status and Forecast of Green House Gas Emissions contribution for different transportation segments (Source: Transport Environment, EEA, EC, Roland Berger)
Due to this, at the end of 2018, the European parliament has approved a corresponding law that determines an interim target of 30% reduction of CO2 emissions by 2030 (in comparison to 2019). A mandatory target of 15% by 2025 (in comparison to 2019) was also agreed upon.
Internal Combustion Engine Bans
Cities and provinces have started a strong campaign to ban internal combustion engines as they consider them to be the major source of particulates causing respiratory and other diseases. As of February 2019, the number of cities and regions globally planning a ban amounted to 30.
Even though some of these bans are still not approved in the legislative and the courts, it shows the direction that several cities are willing to start imposing these types of bans.
Additionally, several cities have started to restrict night deliveries into their cities with focus on noise emissions. Therefore, the need for zero emission and zero noise truck powertrains is imperative to solve this new paradigm.
Tolls
In October 2018, the European parliament backed a 50% discount on road toll charges for zero emission trucks. The new regulation needs approval from the member states before taking effect. Once the regulation is enforced, the toll, which currently depends on the tonnage, fuel and emission type will see another penalty on internal combustion engines.
Also, in October, the German government communicated that they will exempt electric buses
and trucks from road tolls. Based on current toll rates, a 40-ton truck (Euro VI) toll costs 18.7 EUR per 100 km. Considering 120,000 to 240,000 km driven annually on German roads, 22,440 to 44,880 EUR of operating expenses would be saved per truck and year.
In Switzerland, the Swiss federal customs charge commercial vehicle based on the total weight, emission level and kilometers driven in Switzerland and the principality of Liechtenstein (HVC federal tax, i.e. the performance-related heavy vehicle charge). Trucks with electric powertrains are exempt from this HVC federal tax. For example, the road toll charge for a 40-ton diesel truck (Euro VI) would be 91.20 CHF (81.37 EUR) per 100 km. Considering an annual mileage of between 120,000 to 240,000 km, the toll costs would be approximately 109,000 CHF and 219,000 CHF respectively (approx. 97,000 € and 194,000 €).
FUEL CELL TECHNOLOGY
The trucking business rests on the profit potential that can be made by the cost of operating a truck and the corresponding amount received to transport the goods. The TCO of a truck is composed of several factors, for example depreciation, fuel costs, insurance, maintenance, opportunity cost, taxes, tolls, etc. To maximize profit with a truck, its revenues, uptime and freight utilization need to be maximized while minimizing operating costs. These parameters provide the answer why fuel cells can offer a profitable alternative for the trucking business while being zero emission. The reasons why fuel cells are a good alternative, are explained in the next chapters.
Refilling Time
Based on the current refueling infrastructure and refilling times, the amount of km per min that can be refilled for different fuels is compiled in Table 1.
Fuel type Refueling speed
Comments
Diesel 400 km/min 130 L/min*
32 L/100 km** Electricity (250 kW) 1.9 km/min 250 kW*
220 kWh/100 km **
Electricity (1 MW) 7.6 km/min 1 MW* 220 kWh/100 km**
Hydrogen
700 bar today
10 km/min 1 kg of H2/min*
10 kg of H2/100 km**
Hydrogen 700 bar
(H70HF Standard)
100 km/min 10 kg of H2/min*
10 kg of H2/100 km**
* Dispensing rate or power level
** Fuel Consumption or Energy Consumption
Table 1 Refiling Time comparison for Diesel, Fuel Cell and Batteries
ICPC 2019 – 3.1
73
The underlying assumptions (i.e. typical fuel refilling rates and vehicle consumption) for the calculation are noted in the last column.
As one can see, diesel refilling rates are faster than those that can be achieved with refilling/re-charging technologies for fuel cell/battery trucks today. Incumbent diesel technology is about 40 times faster than today’s hydrogen refilling technology, which is about 1 kg of hydrogen per min due to regulatory standard limitations and tank technology (which dictates the size of nozzles and dispensing rate). Recently a consortium of companies was formed and plans to change the standards so that higher refueling rates can be achieved, as shown in the table above. When this body of work is completed, fuel cell trucks could be refilled with up to 100 km/min, requiring only 10 min to be filled up for a 1,000 km trip. Battery charging capabilities are also evolving. Some companies are now evaluating trucks to be charged with a power of 1 MW, which would be enough to reach 500 km of range in 1 hr.
Assuming the best refilling rates for fuel cell and battery, these trucks would be able to have an annual mileage similar to diesel for most use cases. This assumption was made for a typical use case where a long-haul HD truck drives on average 800 km per day with about 1 hour stop for refueling and others. This assumption will vary depending on use cases, driver availability and country regulations.
Total cost of Ownership (TCO)
The TCO of a truck can be calculated using the costs figures as summarized in Table 2
Depreciation Costs 10% of total purchasing costs per year for 10 years
Fuel Costs Electricity: 0.30 to 0.50 €/kWh H2 Cost: 4.0 to 8.0 €/kg Diesel: 0.90 to 1.20 €/L
Insurance Costs 2,660 € for all powertrains
Maintenance Costs
Diesel and Fuel Cell: 10% of powertrain purchasing costs Battery: 5% of powertrain purchasing costs
Opportunity Cost 3% Interest per year applied to total purchasing costs
Toll Costs 18 €/100 Km for Diesel Trucks Zero Emission Trucks exempt
Driver 60,000 €/year
Table 2 Assumptions for TCO Calculation
Using these numbers in a TCO model, AVL determined the TCO of the different truck powertrains. The results are shown in Figure 3.
Figure 3 TCO comparison of diesel, fuel cell and battery trucks
The graph in Figure 3 indicates that fuel cell truck TCO would likely be slightly higher than diesel trucks (7%) but could be cheaper in case hydrogen fuel reaches the best case scenario costs (4 €/kg). Battery trucks remain more expensive than diesel and fuel cell trucks if one were to take the average scenario. Battery trucks could have a similar TCO to fuel cells in case hydrogen costs do not fall below 8 €/kg and energy prices at the charger are equal or less than 0.30 €/kWh. The cost breakdown can be seen in Figure 4 below (Mid Scenario):
Figure 4 TCO break down for different powertrains
As one can notice, fuel costs are dominant for the 3 powertrains, especially for fuel cells and batteries. Second biggest cost driver is the driver. Diesel has an additional toll cost, which is the third biggest cost driver. Powertrain costs, maintenance and insurance play a secondary role in the TCO.
Payload
Another important measure for the trucking business is the total payload that a truck can transport. Trucks are usually rated in terms of total allowed tonnage that they can have while transiting on public highways. Therefore, it is in the interest of the business that the
Diesel Fuel Cell Battery
TCO
35%
5%
33%
18%
1%
5%3%
55%
6%
29%
0%1%
6%3%
60%
8%
22%
0%1%
4%4%
+38%
+7%
Diesel Fuel Cell Battery
ICPC 2019 – 3.1
74
weight of truck and powertrain should be minimized in order to maximize the payload that can be transported. Figure 5 shows a weight comparison of the different powertrains (with current technology and target technology).
Figure 5 Powertrain weight comparison
As it can be seen, fuel cell trucks can already show similar weight as diesel trucks, while battery trucks with similar ranges would weigh 5 to 6 tons more. Most of the fuel cell powertrain weight results from the fuel tanks, due to the number of tanks required to store the required amount of hydrogen. The second biggest contributor is the battery (currently rated at 50kWh) and the fuel cell system, based on 3 fuel cell system modules (i.e., duplication of balance of plant components, piping and housings).
Looking at the future, diesel powertrains will likely remain with the same weight, maybe slightly lower, given typical technology advancements but also considering additional after gas treatment components. Fuel Cell systems have the potential to be about 30% lighter, if one single fuel cell system were to be used (therefore decreasing number of BOPs, enclosures and piping) and reduce the number of tanks by optimizing tank technology, packaging and system efficiency. Battery powertrains also show great potential for weight reduction, with most of the gains coming from the increase in cell energy density. This increase is expected to come from the adoption of solid state batteries which will have approximately 2.3 times higher energy density than current Li-Ion batteries.
TECHNOLOGY CHALLENGES
It is clear by now that fuel cells can be a good alternative as a zero emission propulsion powertrain also for trucks. However, the technology still needs to be further developed to achieve the full potential described above. Among those challenges, this paper
will discuss the most critical of them: cost, durability, packaging and cooling.
Cost
A fuel cell powertrain is made up of several components and their costs are shown below in Figure 6 in comparison with diesel and battery powertrains. The assumptions for the cost calculations are shown in Table 3
Diesel 500 HP Engine
1,000 km Range
Fuel Cell 300 kW Fuel Cell (3 X 100 kW Modules) @ 40 €/kW
500 km Range (52 kg of H2)
50 kWh Battery @ 100 €/kWh
Battery 500 km Range
1,100 kWh Battery @ 100 €/kWh
Table 3 Assumptions for cost calculation
Figure 6 Fuel Cell Powertrain Cost Distribution
The comparison shows that a diesel powertrain is still the cheapest powertrain option, followed by fuel cell system and battery being the most expensive.
Furthermore, the biggest part of the fuel cell powertrain cost is attributed to the hydrogen tank system and fuel cell system. In the fuel cell system, the fuel cell stack is the largest source of cost. Its cost scales linearly with the power required. Therefore, the heavier the truck or the higher the maximum continuous speed requirement, the more expensive the fuel cell powertrain will be.
Since the fuel cell stack cost is directly related to the targeted power, the right-sizing of the fuel cell system
0
1.000
2.000
3.000
4.000
5.000
6.000
7.000
8.000
9.000
10.000
Diesel Fuel Cell Battery Diesel Fuel Cell Battery
Today Future Potential
Wei
ght
(kg)
FCS Tank + Fuel Battery Engine Cooling E/E Rest
Diesel Fuel Cell Battery
Powertrain Cost Comparison
FCS Battery Fuel Tank Rest Motor and E-axle E/E Cooling
+436%
+65%
ICPC 2019 – 3.1
75
is, as stated above, a major challenge. The sizing point of the fuel cell stack and system is determined by considering the required maximum continuous power and the available heat rejection from the vehicle. Furthermore, the cooling capacity and the required electrical power will determine at which efficiency point the fuel cell stack needs to run. The higher the required efficiency target, the larger the necessary active area of the stack (either larger cell active area or higher cell count). Therefore, working on cooling systems that allow the fuel cell to reject more heat is imperative to achieve lower fuel cell system costs.
Another important cost driver will be related to the daily range. Trucks have a relatively large requirement for range. With current requirements of achieving at least 500 km per day, the required amount of hydrogen would be in the range of 50 kg of hydrogen. Today, the available tank alternatives are mostly based on the previous developments for passenger vehicles. These tanks can store about 3 to 4 kg of hydrogen. That means that the number of tanks required are large, which multiplies the number of valves and piping linearly. This adds extra cost that would not be necessary in case of a purpose built tank or usage of liquid hydrogen tanks.
Durability
Typical truck business powertrains are designed to have a durability of 1.0 to 1.5 million km.
Fuel cell durability is defined in different ways. Typically, the durability of fuel cells would mean the number of operating hours that lead to a 10% peak power degradation. This target classification has been inherited from the automotive passenger car development as 10% peak power loss is a degradation level when most customers start to notice a performance decrease during operation of the car. As trucks travel frequently at their max speed (between 80 and 90 km/h, or 60 km/h uphill), even a small reduction in power would be noticed by truck drivers, given the lower speeds that they also travel.
Fuel cells degrade in different ways compared to ICEs. For example, an important degradation mechnaism of fuel cells happens during start up, causing electrode corrosion. In addition, driving in a city in stop/go traffic also causes catalyst degradation due to voltage cycling. Hence, to understand how serious the durability problem is, one needs to understand the failure modes and how often they occur during the typical use cases. Table 4 summarizes the use cases where degradation is normally present and how frequently they are happening.
Degradation Modes
Passenger car
HD Truck
Stop/Go Traffic (#) 350,000 to 400,000
17,000 to 34,000
Long Soak Start Up (#)
6,000 to 13,000
3,000 to 4,000
Freeze Start (#) 2,000 to 2,250 1,500
Hot Operation (h) 200 to 300 200 to 300
Total operating hours (h)
5,000 to 6,000 h or
15 years
15,000 to 30,000 h
or 10 years
Table 4 Expected frequency of typical use cases with influence on fuel cell system degradation for heavy duty trucks and passenger cars
In general, it is possible to ascertain from Table 4 that most of the use cases that typically cause degradation in a fuel cell will be less than or similar to passenger car vehicles. This is due to the typical use case (for example less urban traffic, less freeze start ups, more continuous system operation) and while these trucks are expected to have a major rebuild after the 10 years time, while cars have to last up to 15 years. The difference will be the number of operating hours, which poses a challenge to ensure that every component holds its integrity for almost 5-times more operating hours.
Packaging
Packaging a complete fuel cell powertrain (including hydrogen tanks and battery) in a standard ladder-frame based truck is a challenge. Figure 8 shows the packaging space in a standard 4x2 tractor including the possible volume that can be used to package the hydrogen tanks laterally to the frame (blue marked box). This vehicle configuration is the most challenging for a fuel cell powertrain integration, as the wheel base is short and does not allow for the integration of long hydrogen tanks. It is assumed that the electric drivetrain is integrated in the rear axle. Hence a powerful integrated e-axle has to be developed and integrated in such vehicles to maximize the packaging space for energy storage systems (battery and hydrogen tanks). The packaging space for the fuel cell is shown in Figure 7 too (green marked box). The idea is that the fuel cell should be mounted in the engine compartment to be directly connected with the cooling loop to avoid large pressure drops.
ICPC 2019 – 3.1
76
Figure 7 Available packaging space for fuel cell powertrain components
As already mentioned, the hydrogen tanks will have to be mounted on the blue marked areas. AVL estimations show that approximately 25 kg can be packaged in both blue marked areas with current 700 bar tank technology. This amount of hydrogen will be enough for about 250 km of range. Since this is not ideal, the solution would be to install additional hydrogen tanks behind the cabin.
Current prototype vehicles from Toyota, HMC, and others package their hydrogen tanks behind the driver’s cabin. With current European truck dimension legislation, this would lead to a smaller cabin (no sleeper cabin anymore) or to reduced payload as the cargo volume would be reduced. On the one hand sleeper cabins are required for long-haul applications and on the other hand current truck body systems, like swap bodies, are optimized to use the full vehicle volumes in the range of legislation. Often payload reductions are not acceptable or it has to take place in a way that standardized good sizes fits into the body (load securing or use of standardized pallets).
Therefore, the challenge going forward will be to integrate enough hydrogen on board to ensure a minimum range of 500 km, and an ideal one of 1,000 km avoiding hydrogen tank volumes behind the cabin. Research into new forms of hydrogen storage will be necessary (for example, liquid tanks) including the required infrastructure.
Cooling
Table 5 shows the 3 main continuous vehicle speed scenarios that drive the sizing of a fuel cell system:
ID Vehicle Speed km/h
Road Inclination
%
Ambient Temperature
°C
1 90 0 35
2 80 2 35
3 50 6 35
Table 5 Sizing scenarios for a fuel cell system
For each one of these requirements it is important to calculate the required power and the available cooling capacity. This drives the sizing of a fuel cell system and in turn defines its cost. If there is enough cooling capacity, then the stack active area can be minimized and hence cost can be reduced. If the cooling capacity is not enough then the fuel cell stack needs to be operated at a higher efficiency point (lower areal power density) which will drive cost higher. Figure 8 shows the calculated power for each scenario, the available cooling capacity from current cooling systems and the expected heat rejection from the fuel cell system with an assumed efficiency of 50% (which would optimize the cost).
Figure 8 Power, Fuel Cell Heat Rejection and Available Cooling Capacity
The first conclusion is that for the requirement driving on the flat road, the currently installed cooling capability of the truck is enough. However, for both hill climb scenarios the available heat rejection is not enough at 50% fuel cell system efficiency, which would require a resizing of the fuel cell at higher efficiency point, driving the fuel cells stack costs higher. The problem is more critical for hill climb at 50 km/h, as this scenario requires the cooling capacity to increase by a factor of 3.
One might ask why cooling is such a problem for fuel cells as they normally operate at higher efficiencies than diesel engines. However, there are some
0
50
100
150
200
250
300
350
400
450
500
Flat, 90 km/hr, 0%Incline, 35C
Hill Climb, 80 km/hr, 2%incline, 35C
Hill Climb, 50 km/hr, 6%incline, 35C
Po
wer
, Hea
t R
ejec
tio
n, A
vaila
ble
Co
olin
g C
apac
ity
(kW
)
Power Heat Rejection FCS Available Cooling Capacity
ICPC 2019 – 3.1
77
reasons why cooling is an issue for fuel cells. The first is that today, fuel cells can operate at a maximum coolant temperature of 95 °C, while combustion
engines typically operate between 110 °C and 120 °C.
This is a limitation imposed by the ion exchange membrane, which in theory can be operated at higher temperatures, but since humidification becomes harder at higher temperatures, most systems have been designed to run at 95 °C or even at lower
temperatures. As a consequence, this reduces the temperature difference between the radiator and the ambient air, which leads to less cooling capacity.
Another issue is that the air that is required for the fuel cell reaction, needs to be compressed before entering the fuel cell and it reaches temperatures above what the fuel cell stack and humidifier can tolerate (max 110 °C for humidifier membrane, air compressed can
reach up to 180 to 190 °C). This stream of air needs
to be cooled down by the same cooling loop of the fuel cell system which adds another heat load to the cooling loop.
Since the air entering the fuel cell is already warmed up and will exit at 95 °C, the amount of heat leaving
the fuel cell system through the exhaust is also negligible.
Due to these 3 facts the cooling of a fuel cell system poses challenges which require a new approach either through new radiator designs, more cooling area, higher operating temperatures or new cooling concepts.
AVL SOLUTIONS
AVL has developed over the last years several approaches, tools and methods to address the challenges discussed in the previous section. These are described in the next paragraphs.
Tools and Methods
The overall process of powertrain optimization is a standardized task at AVL.
Optimization of the powertrain or balancing of the individual components respectively is done by using AVL CRUISE M for vehicle simulation in combination with a DoE (Design of Experiment) approach for intelligent parameter variation as well as KPI models for optimization.
As an example, the AVL CRUISE M tool package is used for a full powertrain simulation. The picture in Figure 9 gives an overview on the simulation setup of a fuel cell powered HD application.
Figure 9 Simulation setup from AVL
The basic input for the simulation is a representative driving cycle, with respect to the usage of the vehicle and the target mileage, typically vehicle speed and altitude over time. AVL CRUISE M allows then to map different powertrain configurations (e.g.: different no. of gears, different gear steps, different battery capacities,) to this driving cycle. The properties of each component can easily be modified to match available components (off the shelf components) or to define the requirements of the component (if it needs to be developed).
In the simulation setup shown above, the optimum powertrain solution is achieved when the consumed energy over the driving cycle is at its minimum. (other attributes can be defined based on the individual OEM input or use cases).
Subsequently, the results of the powertrain optimization are:
• Fuel cell max power
• Battery size, evaluation of SOC
• Energy consumption
• E-Motor power (continuous/peak)
• No. of gears/gear ratios Exemplarily, Figure 10 below gives an overview how the underlying driving cycle defines the system power. In this case the powertrain consists of 2 fuel cells systems (FC1 and FC2 with different sizes) which can be utilized according to the operating strategy. The difference between the total power demand and the power of FC1 + FC2 indicates the power / energy which needs to be provided by the battery.
ICPC 2019 – 3.1
78
Figure 10 Fuel Cell and Battery power balancing
Model Based Approach for Durability
As with performance modeling, a high-level powertrain model is used to understand the implications of any energy storage element and the hybridization strategy on how vehicle drive cycles map to actual stack cycles.
Physics-based models of failure modes and stressors permit creation of robust, accelerated lifetime test methods which can be linked through models to actual stack durability estimates in vehicle simulations. These models are also critical to properly cascading verifiable requirements to the subcomponents of the membrane electrode assemblies, like the membrane, or cathode catalyst powder type and loading.
Physical models also allow development of transfer functions for performance degradation cycling tests for subcomponents that are often done in test cells with minimal in-plane gradients, whereas the in-plane gradients present in a full-scale automotive cell cause complexity in both how damage is accumulated, as well as how it manifests in the overall device performance.
Lastly, as many of the stressors tend to be transient in nature, and since there is a wide range of time constants of response of the stack to condition changes, dynamic models are needed to understand the stack degradation response to system inputs. For instance, in response to parameters like current draw, air flow or air pressure, the performance of a stack will change and stabilize within seconds. However, in response to changes to inlet hydration, the time constant of response of relevant parameters to lifetime (i.e. membrane hydration) can be on the order of minutes. This causes the use of static models to
lose resolution on accumulation of damage for several key failure modes and drives the use of transient capable models. The AVL developed models that can account for this different time constants and the dynamics and allow one to generate hydration profiles in the cell as show in Figure 11.
(a)
(b)
Cell Relative Humidity
Figure 11 Cell hydration profile and the estimated durability (a) high temperature, low hydration, (b) target temperature and good hydration
The integration of such physical degradation models of the fuel cell system and battery in the powertrain models enables an optimum sizing of the components as the lifetime degradation of the most costly powertrain components is considered.
Modular Fuel Cell Systems and Operating Strategies
Current fuel cell demonstration trucks make use of fuel cell systems that were designed and developed for passenger car applications or even for stationary applications. However, the different needs of commercial vehicles must be acknowledged and thus dedicated fuel cell systems, considering power output, operating hours, lifetime, and reliability need to be developed.
While current passenger FCEVs share a common targeted fuel cell power that ranges around 100 kW, commercial vehicles possess a large variety of use cases and vehicle weight classes with different power requirements. The rationale of developing dedicated fuel cell systems to high power demands remains questionable as the applicability to different use cases (long-haul, regional and last-mile delivery) might not be given. By taking advantage of an innovative modular fuel cell system approach,
ICPC 2019 – 3.1
79
consisting of multiple smaller fuel cell systems, maximum flexibility to meet requirements of different commercial use cases can be achieved. As such, modular fuel cell systems can be applied to different vehicle classes, e.g. 7.5 t, 18 t, and 40 t classes, depending on the number of modules installed onboard. This approach requires a better understanding of the trade offs of how to operate the several stacks to maximize system performance, durability and robustness. Figure 12 shows an example of 2 cases in which the total power draw from 3 modules is the same, but different variations.
Figure 12 Strategies of power distribution between the systems
Table 6 summarizes the strategy for each system and the expected impact on durability or performance.
CASE 1 CASE 2
FCS1
Full power High heat production Potential degradation due to hot operation
High power Balanced heat production Cell voltage at non-degrading level
FCS2
Low power Degradation due to high cell voltage
High power Balanced heat production Cell voltage at non-degrading level
FCS3
Minimum load to avoid OCV
Idle power Degradation due to very high cell voltage (close to OCV)
Table 6 Comparison of 2 different power distribution strategies
Even though multiple smaller fuel cell systems provide a high flexibility regarding operational strategies, it is inefficient to operate single fuel cell systems at high power while operating others at low power or even idle power considering fuel consumption, heat rejection and durability/lifetime
(see Case 1 in Figure 12). It is better to run fuel cell systems at mid-load where efficiency is high, thus not too much heat is produced, and the cell voltages are in a range that does not cause degradation. Systems that are not needed to fulfill the power request of the vehicle should be shut down completely and only turned on as more power would be requested. In order to achieve a high overall lifetime, the operational hours should be distributed among all fuel cell systems of the truck powertrain.
To achieve the required performance, efficiency, and operational lifetime in commercial vehicle applications, sophisticated monitoring and control concepts are required to mitigate degradation of the fuel cell system. Typically, the fuel cell hybrid system is comprised of the fuel cell itself as well as additional energy-storage devices (such as HV batteries and super/ultra-capacitors). The primary control goal is to meet the required power demand (i.e. the requested mechanical power) at all times, while operating the fuel cell and energy-storage devices within their optimal regions. The energy-storage devices are charged via recovered braking energy (recuperation) and via the fuel cell system when the overall power demand is low. Accordingly, these components are used to supply peak power and represent a long-term energy buffer. Besides the mechanical/driving power, major electric loads may also occur from vehicle auxiliaries like refrigeration units (in refrigerated cargo vehicles), which have a substantial influence on the overall powertrain and fuel cell system operating strategy.
Due to the variability of possible system configurations and dimensions in HD vehicles regarding energy storage-devices and electric loads, modularity is the key to foster efficiency and lifetime improvements of the interconnected powertrain elements. Balancing of loads over multiple fuel cell systems will result in maximizing the energy efficiency of the overall fuel cell powertrain by reducing the load that is applied onto each single system. Obviously, maximum powertrain efficiency further increases the driving range of the truck and keeps the heat rejection of the fuel cell systems at a reasonable value, simplifying the cooling system. At the same time, durability- and lifetime-impairing operating conditions can be avoided by maintaining preferred cell voltages in each stack.
While balancing of electric loads over several fuel cell systems is an important measure to reduce stack degradation, additional levers need to be triggered to achieve targeted operational lifetimes in commercial vehicle applications. As such, reduction of system dynamics is a key solution.
ICPC 2019 – 3.1
80
Figure 13 Examples of dynamic operating strategies for modular fuel cell systems
Assuming a dynamic power request of 125 kW/s, as shown in Figure 13, it is obvious that a single high-power fuel cell system will need to bear the full load change by itself (Figure 13a). In contrast, in a fuel cell truck powertrain consisting of multiple smaller fuel cell system modules, lower dynamic load changes need to be borne on system level while achieving the same overall 125 kW/s power request on powertrain level (see Figure 13b and Figure 13c). At lower power demands, single fuel cell systems in a modular fuel cell powertrain could even be turned off, reducing the overall number of operating hours of each system, thus potentially prolonging the overall powertrain durability and lifetime (Figure 13c).
Real Time On-Board Diagnostics
In order to achieve highest durability of the fuel cell stacks, the operating strategies need to consider the
actual state-of-health of the stacks while calculating the setpoints for each actuator. Typically, the state-of-health is determined by monitoring the voltage of each single cell in the stacks. A deviation from the expected cell voltage would indicate that the cell or cells are operated in an undesirable condition, which could result in accelerated degradation of the stack. However, the voltage value does not provide insight into the underlying cause of the problem, thus a dedicated countermeasure cannot be taken, and a series of potential measures need to be performed following a certain reaction matrix. The application of such a cell voltage monitoring (CVM) remains questionable, considering the high number of sensors (>400 per stack), the associated cost and low quality of information.
In contrast, AVL developed a methodology, called THDA (Total Harmonic Distortion Analysis) that allows to distinguish between different root-causes of degradation-triggering operating conditions, while at the same time reducing the number of sensors to two per stack. Despite the low number of sensors, AVL’s methodology and algorithms are powerful enough to still achieve single cell resolution, providing comprehensive state-of-health information from single cell to stack level. THDA detects whether the stack is operated in too dry or too wet conditions, resulting in membrane dry-out or flooding and whether there is a starvation of reactants. This additional information on the root-cause enables targeted countermeasures and thus reduces the time in which the stack is operated in lifetime-impairing conditions, thus prolonging the overall durability of the fuel cell powertrain. Since the methodology can be implemented directly into the fuel cell controls and the fuel cell DC/DC boost converter, no additional hardware cost is added to the fuel cell powertrain, thus achieving a significant cost reduction compared to the current state-of-the-art cell voltage monitoring.
E/E Integration
As the power levels required for HD trucks are high, the usage of high voltage systems is normally preferred. This means that the connection of several fuel cell systems and batteries to the inverters and motor needs to be done with different DC-DC converters. AVL has investigated several DC-DC converters solutions and created several trade off models that can be used.
ICPC 2019 – 3.1
81
Figure 14 shows the potential DC-DC converter configurations that could be used to connect the fuel cell systems. Each one of them has different trade offs that need to be observed based on the customer requirements.
Figure 14 Potential DC-DC converter wiring
CONCLUSION
Fuel cells can offer several advantages as a zero emission powertrain for heavy duty trucks. These advantages are related to the quicker refilling times, low weight and low total cost of ownership. However, the technology still has several challenges in a truck vehicle with regard to cost, durability, cooling and packaging. AVL is engaged in solving these issues by offering innovative solutions like modular fuel cell systems, advanced operating strategies, high voltage boost converters with integrated real-time on-board diagnostics as well as all necessary simulation and testing environments. AVL will continue to work and advance the technology focusing efforts in the years to come on the hydrogen storage, fuel cell system cost and cooling issues, so that weight and cost can be addressed and reach the targets set forth by the industry.
ACKNOWLEDGMENTS
The authors would like to thank all contributors to this paper from AVL Fuel Cell Canada (Amy Nelson, Roger Penn, Sascha Mielke) as well as from AVL Graz (Christian Niedermayr, Armin Traussnig, Franz Hofer) and AVL Steyr (Wolfgang Gruber, Michael Kordon).
REFERENCES
[1] FCH Europe, 2017. Development of Business Cases for Fuel Cells and Hydrogen Applications for Regions and Cities - FCH Heavy-duty trucks. Online: http://www.fch.europa.eu/sites/default/files/171121_FCH2JU_Application-Package_WG1_Heavy%20duty%20trucks%20%28ID%202910560%29%20%28ID%202911646%29.pdf, accessed on March 29, 2018
[2] AVL: Hybrid fuel cell powertrain. In: Electric & Hybrid Vehicle Technology International 01/2018, S. 176
[3] Schenk, A, Berg, F, 2018, 'Konzeptfahrzeug mit Brennstoffzellen-Plug-In-Hybrid', ATZ 10/2018, pp. 30-35
[4] Rechberger, J, Schenk, A, 2017, 'Auslegung der Medienversorgung für ein automobiles Brennstoffzellen-System’ Ladungswechsel im Verbrennungsmotor 2017 - 10. MTZ-Fachtagung Proceedings. Springer Vieweg, Wiesbaden, pp. 1-12, DOI: 10.1007/978-3-658-22671-8_6
[5] Berg, F, Schenk, A, 2018 ‘ PEM fuel cell powertrain – which application makes sense – a study’ Eco-Mobility 2018, Vienna, November 13, 2019
DEFINITIONS, ACRONYMS, ABBREVIATIONS
OEM Original Equipment Manufacturer.
TCO Total Cost of Ownership
ICE Internal Combustion Engine
DOE Design of Experiments
SOC State of Charge
FCEV Fuel Cell Electric Vehicle
OCV Open Circuit Voltage
HV High Voltage
HD Heavy Duty
CVM Cell Voltage Monitoring
THDA Total Harmonic Distortion Analysis
82
ICPC 2019 – 3.2
Commercial vehicle battery solutions
Krzysztof Paciura
Cummins Inc. Copyright © 2019 AVL List GmbH, Cummins Inc.and SAE International
ABSTRACT
This paper describes the research and development journey that Cummins Inc. is taking to secure a market-leading position in electrified powertrains for commercial vehicles. Accelerating the migration from existing internal combustion engines (ICE), these developments underpin the next-generation of more-electric propulsion solutions, including full electrification and hybrids using efficiency-optimised thermal propulsion. As well as summarising all of these activities, here Cummins introduce the development of a novel approach to high power density electric traction based on Synchronous Reluctance Permanent Magnet Assisted electrical machines, and discuss integration of power electronics and other electrification accessories.
INTRODUCTION
Who are Cummins Inc.?
Cummins are the world's leading independent producer of diesel engines for commercial applications, ranging from 55 to 3,500 horsepower. As well as diesels, Cummins currently design, manufacture and supply a complete line of natural gas engines for many on-highway and off-highway markets, including heavy-duty and medium-duty trucks, buses and plant equipment. Additionally, Cummins supply engines into multiple industrial and power generation applications including agriculture, construction, mining, marine and military equipment.
Cummins have realised significant vertical integration in the supply chain, and also develop and supply value-added auxiliary components and subsystems across the electric machine, electromechanical machine and electronic system domains. Cummins can subsequently leverage globally-leading expertise and joint development partnerships with key stakeholders within the group as follows.
Electric machines: Cummins Generator Technologies have proven prominence globally, and currently manufacture the world's broadest range of AC
generators from 0.6 kVA to 20,000 kVA under the MARKON®, STAMFORD® and AvK® brands.
High-speed electromechanical machines: Expertise is assured through Cummins Turbo Technologies and Holset, who are one of the world’s largest turbocharger manufacturers with annual sales circa $1 billion, having been integrated into the Cummins family of brands in 1973.
A changing world for propulsion
However, whilst the diesel engine has revolutionised transportation and industry, particularly in medium and heavy-duty applications, the landscape for this success is changing. It is now known that trucks used for regional and urban logistics cause up to 45% of air-pollution in and around built-up areas, with devastating environmental and socio-economic impacts. The UK alongside many other countries targets migration to a zero-emission vehicle fleet over the coming decades, but a significant number of cities including London, Paris and Barcelona have commited to blanket diesel-bans far sooner, fundamentally risking logistics chains.
Battery electric vehicles (BEVs) remain the most credible approach to address this challenge, but whilst the broader evolution is occuring incrementally alongside both technology-driven and organic cost reductions, the immediate need for cost-effective commoditised medium and heavy duty BEV powertrains remains unmet. In the meantime, the role of efficient thermal propulsion and hybrid technology is vital to realise rapid reductions in CO2 emissions.
Cummins’ journey towards electrification
Cummins aim to be at the forefront of this new electric powertrain revolution, with a technology-driven approach to secure a position as the world’s leading provider of end-to-end electrification solutions in the on and off-highway sectors.
Cummins established a dedicated Electrification Team in 2017 to support their Research and Technology ambitions in this space, which are central
ICPC 2019 – 3.2
83
to their overall global product roadmaps. The Electrification Team ensure that Cummins continue to make the best possible strategic decisions in terms of internal investments in component and system technologies, building the new capabilities needed, and stimulating the external partnerships to meet their customers' needs in these prioritised markets.
Cummins have already gained significant expertise in powertrain electrification, and have long been the largest supplier of engines for hybrid commercial vehicles. Targeting the progression to zero emissions, over the last 15 years Cummins’ global Research and Technology team has been privately and publically developing a range of diverse electrification technologies, which can be applied directly to improve combustion engine efficiency and CO2 performance, as well as enable hybridisation of ICE-based powertrains and full electrification in the future.
During this period Cummins have successfully completed many high-profile projects from concept-level upwards, actively partnering with legislators, suppliers and customers to realise new more-electric powertrain solutions.
Maintaining vertical-integration of the components with the largest impact on performance, quality and system power, Cummins have also recently acquired Brammo and Johnson Matthey Battery Systems, to ensure strong capability in energy storage as part of the end-to-end electric powertrain offering.
CUMMINS CURRENT ELECTRIC POWERTRAIN PORTFOLIO
Cummins’ vision to penetrate the growing market for electrification technologies is evidenced by the commercial entry of a first generation of these products, summarised as follows.
Electric machines
Focussed initially on high-speed electromechanical machines, Cummins have developed a number of proprietary technologies for energy recovery [1].
E-COMPOUNDING ENERGY RECOVERY
Cummins have developed and integrated a suite of high-speed electromechanical machines which enable energy recovery from exhaust gases, as well as enhancing efficiency through electrically-assisted compression of the inlet and recovered airflows to the combustion engine.
Figure 1 High-speed electrical machines for the more-electric engine.
ELECTRIFICATION OF WASTE HEAT RECOVERY
These approaches have been further explored to realise novel architectures for electrically-assisted turbocharging, realised by integrating new electrical machines with existing high-speed machinery. Cummins are also implementing thermal heat recovery mechanisms for further efficiency gains.
Figure 2 Electrically-assisted turbocharger design.
HYBRID TECHNOLOGIES
Cummins have scaled these developments to realise a highly compact but powerful permanent magnet motor topology. This can be used for direct drive propulsion in pure BEV or range-extender solutions for early adopters, alongside a downsized 2.8L EURO 6 engine, or in hybrid stop-start applications.
ICPC 2019 – 3.2
84
Figure 3 Hybrid powertrain integration for a range-extender electric vehicle.
Battery Packs
Through strategic growth and partnerships, Cummins have a full range of proprietary battery technology, to support energy recovery and plug-in electrification.
Figure 4 Cummins’ modular pack architecture.
Modules: Focussing on individual customers’ unique operations and needs, Cummins’ high energy density modules underpin significant scalability and flexible vehicle-level integration.
Enclosure: Cummins have applied advanced composite materials to realise a super-lightweight case, increasing energy density and durability.
Battery Management System: Cummins have developed proprietary control architectures to maintain safe operation and isothermal management under extreme operating conditions.
THE TECHNICAL CHALLENGE OF FULL ELECTRIFICATION
Electric machines
The drive-cycles and diverse payload conditions of medium and heavy duty trucks place extreme demands on the powertrain performance in terms of: startability (peak torque at wheels above 20,000Nm – 2710Nm at differential, using standard trans-axle ratio); gradeability (continuous torque at differential 1,000Nm); speed (0-3000RPM at differential at 2710Nm); and corresponding power (>200kW). High powertrain efficiency over the whole drive cycle is also a vital consideration for mainstream adoption.
Whilst only partially meeting these torque and speed requirements, the existing state-of-the-art BEV powertrain architectures based on synchronous motors commonly contain up to 100kg of rare-earth permanent magnets as the primary excitation medium to generate the very high fields required.
As well as restricting the cost, weight, size and efficiency over the drive-cycles targeted, dependence on highly volatile mineral resource supplies of these exotic materials fundamentally prevents commoditised volume manufacture, and capability to meet future electrification demands.
Power electronics integration
Electric powertrains must also compete with ICE architectures in terms of vehicle-level and system-level integration. ICE power units are already highly integrated, having matured over many product generations to include all of the key auxilliary functions into a single warrantied product.
In contrast, this level of integration is yet to be realised for BEV powertrains, for which the primary challenge faced by technology developers of key subsystems and components – such as power electronics and controls – has been realising the baseline functionality to achieve the operational performance requirements. The integration challenge extends far beyond the interfaces and electro-mechanical aspects, and thermal management of electronic components becomes critical given the temperatures expected as they approach their limits to deliver the extreme performance targeted.
ELITS: EFFICIENT LIGHT INTEGRATED TRACTION SYSTEM
In response, Cummins – working closely with the University of Nottingham’s Power Electronics, Machines and Control Group – are developing totally new high power architectures for medium and heavy duty BEV powertrains, which are highly integrated and require no rare-earth permanent magnets.
ICPC 2019 – 3.2
85
Cummins’ approach
Using extreme gearing to radically reduce the motor peak-torque requirement, Cummins aim to deliver a breakthrough in power density by uniquely targeting an increase in electric machine speed within this context. This is being developed alongside direct-integration and cooling of power electronics into the traction motor housing, enabling intelligent control in a single or modular motor configuration.
Figure 5 Power-speed and torque-speed curves.
With this industrial-academic partnership yielding a number of novel high-speed reluctance machine topologies, Cummins are now focused on scaling and integrating disruptive synchronous reluctance motors into scalable powertrain systems, which only require minimal permanent magnet assistance.
Figure 6 Magnetic field distribution at high speed.
Electric machine performance
The step-change in maximum revolutions-per-minute (15,000 RPM) in a motor of this size and cost is fundamental to Cummins’ capability to uniquely deliver efficient power up to 220kW over an unprecedented range of motor speeds, using only very low permanent magnetic fields.
Transmission development
Also central to the solution is the development of an integrated multi-speed transmission, which is capable
of delivering extreme startability (20,000Nm at the wheels) and 10,000Nm continuous torque at speed.
Power electronics
The development of proprietary power electronics will focus on the intelligent control of the rotor to support safe and reliable operation at the motor speeds targeted, as well as shared cooling with the electric machine to enable direct integration without the addition of further auxiliary components.
Modularity and scalability
Interfaces for plug-and-play modularity are critical to scale the technology for heavy-duty applications, including the wide range of off-highway market sectors of strategic importance to Cummins.
INNOVATION OUTPUTS
The design-performance of these topologies corresponds to a 5-fold increase in maximum efficient motor speed in a >200kW motor, for which reluctance excitation alone is insufficient. However, the novel stator and rotor design is shown (by simulation and prototyping) to achieve the characteristic rpm.√kW greater than 200,000, which reduces the generation torque requirement of permanent magnets from 70%→10%. With careful engineering of the magnet properties and integration, this breakthrough enables low-cost ferrite material to replace rare-earth magnets, catalysing a 100-fold reduction in raw material costs, and an unconditional supply chain.
The work within the ELITS programme therefore yields the first cost-effective alternative to permanent magnet synchronous-motors for medium and heavy duty BEV powertrains. Innovations address the specific technical challenges of safely and reliably achieving these motor speeds.
STATOR
ELITS leverages new electrical-material development (6.5% Si-steel), lamination engineering, distributed-winding geometries and advanced cooling.
ROTOR
Embodied by high-strength materials, lamination and domain geometries optimising reluctance-excitation, ferrite integration and direct cooling.
ICPC 2019 – 3.2
86
Figure 7 Rotor geometry parameter space [2].
Figure 8 Reluctance torque based on the distribution of total barrier thickness [2].
CONCLUSION
Cummins have invested heavily in electrification technologies over the last decade, focussing on the critical components of electrified powertrains and leveraging the unique skillset across Cummins’ employee base, including mechanical, thermal, rotor dynamics, electro-magnetics and power electronics engineers. As a result, Cummins is ideally positioned to become a leader in the electrification value chain as a global Tier 1 supplier. The technological innovations stimulated by the ELITS project give Cummins a competitive advantage in electrical machine design and power electronics development, specifically targeting medium to heavy duty powertrains in sectors which are key to reducing the environmental impact of diesel transport, in line with global government-level ambitions and legislation.
REFERENCES
[1] Gerada, D et al. (2013), High-Speed Electrical Machines: Technologies, Trends, and Developments. Members, IEEE. Volume: 61 , Issue: 6 , June 2014.
[2] Walker, A et al. (2016), Development and Design of a High Performance Traction Machine for the FreedomCar 2020 Traction Machine Targets, Members, IEEE.
[3] Nardo, M et al (2016), Comparison of Multi-physics Optimization Methods for High Speed Synchrnous Reluctance Machines. Members, IEEE. Cummins Generator Technologies, Stamford, UK
[4] Gerada,D et al. (2011), Electrical Machines for High Speed Applications with a Wide Constant-Power Region Requirement.
[5] Erik Odvarka, E et al. (2009), Electric Motor-Generator for a Hybrid Electric Vehicle, Journal of Engineering Mechanics.
87
ICPC 2019 – 3.3
The smart eCVT hybrid system for 2020+ Commercial vehicle application
Dr.Zhiqiang Lin, Song Zhang, Tao Chen, Zhengsong Mao
Guangxi Yuchai Machinery Co., LTD
Dr. Christoph Schoerghuber
AVL Commercial Driveline & Tractor Engineering GmbH, Steyr
Copyright © 2019 AVL List GmbH, John Deere and SAE International
ABSTRACT
In this paper a new e-CVT hybrid system for various commercial vehicle applications is presented. This new hybrid system is combining the power sources of a combustion engine with two high-speed e-motors which are highly integrated into the e-CVT transmission. With the help of a new transmission concept including different operating modes, high efficiencies combined with comparatively low product cost are achieved. The high efficiency of the powertrain and the perfectly coordinated interaction of the three power sources ensure high fuel savings without compromising drivability and driving comfort. This is achieved, in particular with dynamic load profiles as they are usual for city bus applications, via power-split and pure electric vehicle operation mode. In addition, an overdrive operating mode enables efficient driving at constant high vehicle velocities for highway applications. Thereby, an optimum operating range for the combustion engine is achieved via a mechanical power flow and parallel hybrid operation. The operating mode is selected on the basis of a well-developed hybrid strategy. Furthermore, the hybrid system can be easily adapted to different commercial vehicle applications. The optional equipment with a PTO module with pure electrical and mechanical operation makes the e-CVT system also suitable for many truck applications.
INTRODUCTION
The development of highly efficient commercial vehicle powertrains is subject of ongoing research and development activities all over the world. Reduction of fuel consumption is the main driver for hybridization of commercial vehicle powertrains. But
next to the achievement of highest fuel consumption benefits, one of the main targets for Yuchai is the flexibility to apply the transmission to different commercial vehicle applications. Target applications of the developed hybrid powertrain are city buses but also highway coaches and medium duty trucks such as concrete mixers, cranes or delivery trucks with a gross vehicle weight between 16 and 20 tons. Thus, the powertrain must achieve high system efficiencies for city as well as overland and highway driving and must be adaptable to different maximum vehicle velocity and gradeability requirements. Also, a PTO unit is required for some of these applications.
AVL developed for Yuchai a new hybrid powertrain system which exactly fulfills these demands. Via electric power split with continuous variable transmission (CVT) property and further transmission modes this smart e-CVT hybrid system enables lowest fuel consumption for different commercial vehicle applications. Due to its modular and comparatively simple design the hybrid powertrain can be adapted to different applications with moderate production costs.
MECHANICAL LAYOUT OF THE E-CVT HYBRID SYSTEM
The powertrain consists of the engine (ICE), 2 electric motors (e-motors), a battery, a dry clutch, the e-CVT and the rear axle. The e-CVT consists of the input shafts for the e-motors and the engine, gear boxes for speed reduction of the e-motors, a mode selector unit, 2 planetary gear sets including (hollow) shafts, the transmission output shaft as well as a limp-home and PTO unit.
ICPC 2019 – 3.3
88
Figure 1 Renderings of the designed e-CVT hybrid system
In Figure 1 renderings of the finally designed e-CVT hybrid system can be seen.The left-hand side picture shows the e-CVT transmission with the two e-motors and the dry clutch actuation including a view into the gear box. The powertrain including engine, dry clutch and e-CVT with both e-motors but without rear axle and battery can be seen on the right-hand side. The e-motor 1 (EM1) is connected to the sun gear of planetary gear set 1 (PG1). In between there is a gear box with fixed gear ratio. The ICE is connected to the dry clutch which then is connected to the carrier of PG1. The e-motor 2 (EM2) is connected to the sun gear of planetary gear set 2 (PG2). In between there is a shift able gear box with 2 gears as well as a neutral position. The carrier of planetary gear set 2 (PG2) is fixed to the housing of the e-CVT. The rings of both planetary gear sets are connected to the transmission output shaft. Thus, there is a fixed ratio between sun and ring gear at PG2, and EM2 is always connected to the transmission output shaft, since a gear is engaged at EM2 gear box. PG1 is acting as power split or summation device enabling a CVT operation of the transmission.
Furthermore, the transmission consists of a mode selector unit where either the sun gear or the carrier of PG1 can be blocked to the housing. Thus, additionally to the CVT-mode a pure electric vehicle mode (EV-mode) and a direct ICE mode with overdrive gear ratio (OD-mode) can be selected. The different transmission modes are chosen very carefully. Therefore, different hybrid and electric powertrains are investigated in a first step.
Investigations on standard layouts of electrified powertrains
Studies on serial and parallel hybrids as well as pure electric vehicles form the basis for the development of the transmission modes. Compared to parallel hybrids, serial hybrids are preferable due to high driving comfort and comparatively simple mechanical topology and control strategy. Serial hybrids do not require shift able transmission and thus can be
operated without any torque interruption leading to highest driving comfort. Due to the battery as energy storage device the electric motor and generator are almost independent from each other and can be controlled separately. For highly dynamic drive cycles high fuel consumption benefits are achievable also because the engine can be always operated at best fuel consumption point, independently from vehicle velocity. But for driving at constant (high) speeds the electric efficiency chain from generator to motor gets quite bad resulting in higher fuel consumption. Furthermore, the mechanical layout requires high power for engine, electric generator and motor and thus product costs are quite high.
Parallel hybrids require only one electric machine with moderate power and the mechanical layout is quite similar to conventional powertrains which has positive effects on product and integration costs. High system efficiencies are achievable also for driving at constant high speeds because of the mechanic power flow and the possibility of load point shifting of the engine or boosting. However, the engine cannot be operated at best fuel consumption point continuously because engine speed and vehicle velocity are always coupled, and their relation is depending on the selected gear. Thus, for city and overland driving highest fuel consumption benefits cannot be achieved with parallel hybrids. Furthermore, there are torque interruptions during gear shifting of transmission which are affecting the driving comfort of the vehicle negatively.
Battery electric vehicles require only one electric machine with full power and can be operated in zero emission zones. For medium and heavy-duty commercial vehicle applications they are typically equipped with shift able transmissions to increase gradeability for vehicle start-up. Thus, there are torque interruptions during gear shifting of transmission which are affecting the driving comfort of the vehicle negatively. Furthermore, electric
ICPC 2019 – 3.3
89
vehicles require big battery capacities to achieve acceptable driving range.
Properties of the developed transmission modes
To combine all the advantages of the described electrified powertrains the developed e-CVT hybrid
system is equipped with different transmission modes enabling the powertrain to be operated as power-split hybrid, parallel hybrid and pure electric vehicle. In Figure 2 the layouts of serial and parallel hybrids as well as electric vehicle powertrains are compared to the different modes of the e-CVT hybrid system.
Figure 2 Layout comparison of serial hybrids, parallel hybrids and electric vehicle powertrains with the different modes of the developed e-CVT hybrid system
The e-CVT hybrid system in electric power split operation mode (CVT-mode) allows the ICE always operating at best fuel consumption point resulting in highest powertrain efficiencies as well as driving comfort. The resulting properties are similar to those of serial hybrids with the advantage of an additional mechanical power flow, leading to a further increase of efficiency. Via OD-mode the same properties as for parallel hybrids can be achieved resulting in highest efficiency values even for highway driving. Via EV-mode the powertrain can be operated with zero emissions and recuperated battery energy can be utilized for vehicle propulsion.
Due to the combination of electric and mechanic power flow enabled via the different modes the overall system power is resulting as a combination of ICE and e-motor power individual power values of the different power sources can be reduced compared to e.g. serial hybrids, leading to lower production costs. Thus, with the help of the new developed e-CVT hybrid system the advantages of serial and parallel hybrids as well as electric vehicles are combined.
EXPLANATIONS ON THE E-CVT HYBRID SYSTEM MODES
EV-mode
If EV-mode is selected the carrier of PG1 and thus the engine shaft is blocked to the housing of the e-CVT hybrid system. Similar to the connection of EM2, EM1 is always connected to the transmission output shaft with a fixed gear ratio. Because of limited battery capacity the EV-mode is typically used for low vehicle velocities. The energy for vehicle propulsion is provided by the battery to both e-motors. The requested transmission output power in general is provided by both e-motors as sum of the individual power values for vehicle propulsion and recuperation.
OD-mode
If the sun gear of PG1 is connected to the housing, EM1 input shaft is blocked and thus EM1 is not used. In this so-called OD-mode there is a fixed ratio between ICE and transmission output shaft with an overdrive gear ratio. Due to the resulting engine operating points at small engine speed regions for high vehicle velocities the OD-mode is enabling high
ICPC 2019 – 3.3
90
system efficiencies for highway driving. If EM2 gear box is switched to neutral the vehicle is driven by the ICE only. If a gear is selected at EM2 gear box, additionally EM2 is connected to the transmission output shaft and the powertrain is operated as parallel hybrid. The OD-mode can only be used for higher vehicle velocities because the engine’s idle speed is limiting the minimum vehicle velocity. The requested transmission output power in general is provided by the ICE and EM2 as sum of the individual power values. Thus, this mode can be used for both vehicle propulsion and recuperation.
CVT-mode
If neither PG1 sun gear nor PG1 carrier are blocked, the e-CVT hybrid system is operated in CVT-mode as continuous variable transmission, i.e. the ratio between transmission output and transmission input shaft can be adjusted between 0 and a certain finite value continuously. The requested transmission output power is provided by the ICE, EM1 and EM2 as sum of the individual power values. Because of the power split of mechanical to electrical and back to mechanical power, one e-motor typically is operated as generator and one e-motor as motor. Thereby, PG1 is acting as power split and summation device. In this CVT-mode it is possible to operate the ICE at best fuel consumption point and to choose the split between ICE power and battery power provided to the e-motors within certain limits for further efficiency optimization.
FUEL CONSUMPTION SIMULATION OF A CITY BUS WITH E-CVT HYBRID SYSTEM
For estimation of fuel consumption benefits which are achievable with the e-CVT hybrid system an overall vehicle simulation of an 18-ton city bus is performed. The vehicle simulation is done with AVL Cruise based on longitudinal dynamics of the vehicle. The powertrain model is split into engine (including 0,5 kW constant mechanic auxiliaries), e-CVT (including e-motors), battery (including battery management and 1 kW constant electric auxiliaries) and rear axle. Additional to the mechanical parts of the hybrid powertrain also the transmission controller (TCU) and the hybrid controller (HCU) must be considered within vehicle simulation. The e-CVT and the required controllers are modelled in Simulink and implemented as dynamic link libraries into the powertrain model in AVL Cruise.
To perform a fuel consumption comparison an additional simulation of the same city bus with identical engine (including mechanic auxiliaries) and rear axle but with automatic transmission (AT) and torque converter is performed. Thereby, a state-of-the-art AT transmission, a torque converter with lock-up clutch and an engine with start-stop function are modelled. Both Cruise vehicle models can be seen in Figure 3.
Figure 3 AVL Cruise vehicle simulation of a city bus. Left hand side: Conventional city bus powertrain with torque converter and AT; Right hand side: city bus powertrain with DHT.
For fuel consumption comparison, both vehicles are simulated driving on the Chinese city bus cycle
(CCBC). The resulting engine operating points for both powertrain models are depicted in Figure 4.
ICPC 2019 – 3.3
91
Figure 4 Engine operating points of a city bus vehicle simulation driving on CCBC drive cycle. Left hand side: City bus powertrain with torque converter and AT; Right hand side: City bus powertrain with DHT.
As can be seen the engine operating points of the conventional powertrain are located in a big region below 1500 rpm. Whereas the engine operating points of the powertrain with e-CVT (in CVT-mode) are located at the best point curve, connecting the best fuel consumption points depending on engine power. The resulting fuel consumption results are depicted in Figure 5.
Figure 5 Simulated fuel consumption results of an 18t city bus driving on CCBC drive cycle with conventional and DHT powertrain.
The fuel consumption results of the powertrain with e-CVT are based on a balanced state of charge of the battery where battery energy at beginning and end of the simulation is identical. With the e-CVT hybrid system a fuel consumption benefit of about 38% can be achieved. This benefit is a result of operating the engine at best point curve, recuperation of braking power, engine start-stop and driving purely electrically utilizing the recuperated battery power.
SUMMARY AND CONCLUSION
A new hybrid powertrain with e-CVT transmission for commercial vehicle applications was presented in this
paper. The carefully developed gear arrangement results in positive properties for different commercial vehicle applications. The mechanical layout is comparatively simple and offers the use of high-speed e-motors, resulting in optimum packaging and low product costs. With the help of a mode selector unit the new developed e-CVT hybrid system combines and improves the advantages of serial and parallel hybrids as well as pure electric vehicle powertrains. Via a power split operation mode with continuous variable transmission function (CVT-mode) the engine can be operated at best fuel consumption point. In addition, an engine direct drive mode with overdrive gear ratio and parallel hybrid function (OD-mode) allows the engine to operate in areas with highest efficiency, resulting in lowest fuel consumption even when driving on highway cycles. Furthermore, an electric vehicle mode (EV-mode) is used to drive with zero emission and to utilize the recuperated battery power. The simulation results show the big benefits in terms of fuel consumption compared to conventional state-of-the-art powertrains, i.e. the fuel consumption can be reduced by 38% with the help of the e-CVT hybrid system.
Optionally the e-CVT system can be equipped with a limp-home and a PTO module. The limp-home module ensures a safe trip with reduced functionality even in electric failure mode of the e-CVT hybrid system. The optional equipment with a PTO module with pure electrical and mechanical operation makes the e-CVT system also suitable for many truck applications.
REFERENCES
[1] EP-0967102A2
[2] CN-203766482U
[3] Müller, H.: Die Umlaufgetriebe. Springer 1998
92
ICPC 2019 – 3.4
Tractor/implement systems – the next generation
Dr.-Ing. Joachim Sobotzik
John Deere European Technology Innovation Center Kaiserslautern, Germany
Craig Puetz
John Deere Global Tractor Engineering, Waterloo, IA, USA
Copyright © 2019 AVL List GmbH, Guangxi Yuchai Machinery Co., LTD and SAE International
ABSTRACT
Electric dive systems are applied in vehicles and mobile machinery since decades, wherever the emission-free operation was required. E.g. in the material handling industry, electric drives represent the state-of-the-art, being integrated in a variety of system configurations, from basic operator controlled battery-electric systems to hybrid architectures where partial battery electric operation, the availability of an onboard power generation system and sophisticated power controls can be integrated.
In passenger cars and commercial on road vehicles, hybrid power trains, consisting of an electric drive system, battery energy storage and a combustion engine have gained a noticeable market share, particularly since the exhaust gas after treatment for diesel engines required significantly increased efforts driven by the latest emission regulations.
In precedent publications [1] three categories of electric drive application in off road machinery were discussed:
Engine and vehicle auxiliary drives, e. g. radiator fans, coolant pumps, AC-compressor drives, substitutes for alternators.
Power transfer from a mobile power source like a tractor to attachments, e. g. agricultural implements.
Traction drive systems, e. g. on construction machines, passenger busses, etc..
The future availability of electric energy storage systems, has been labelled as a separate fourth area of application for electric drives. The availability of energy storage systems is going to trigger innovative solutions, from complementing conventional vehicle configuration thru hybrid structures to completely new
architectures, not practicable with traditional approaches.
The current work is built on merging of the 2nd and 3rd category to create a next generation of agricultural systems, highly integrated tractor-implement propulsion systems.
Tractors and implement designs have shown significant progress in the last decades. Anyway, getting closer to the performance and productivity of highly optimized and specialized self-propelled machinery, tractor/implement systems continuously increased in size and weight. One cause for less-than-optimum systems has been the independent optimization of tractors and implements, gains possible thru integrated systems were not realized.
A key advantage coming with distributing traction forces from the tractor to implements, using traction assist axles, has been demonstrated and realized in the past. Less tractor weight and improved payload on implements were initial targets. Managing the efficiency of the overall system, tractor, implement and process is expected to drive additional improvements.
The paper will describe test results and expected improvements coming with a tractor-centric efficiency management for traction drives in combination with implement driven process optimization and state-of-the-art sensing technologies.
Relative to tractors, the ongoing developments will show significantly increased power densities based on lightweight chassis and high output drivetrains. Relative to implements, improved operating strategies and new sensing technologies discovered are enabling significant productivity improvements. In combination this is getting tractor/implement systems
ICPC 2019 – 3.4
93
closer to the performance of self-propelled machinery.
Particularly distributed traction is approaching the efficiency of self-propelled machinery while maintaining versatility and year-round usage of the investment.
ELECTRICAL POWER FOR AGRICULTURAL IMPLEMENTS
Farmall 450 with IH ElectrAll, 1954
While the first approach has been initiated already about 60 years ago, in 1954 when IH introduced the IH Farmall 450 with an integrated electric power generator (see Figure 1), the IH ElectrAll system, mobile electric drive applications became significantly more attractive with the introduction of IGBTs
(Isolated Gate Bipolar Transistor), efficient and cost-attractive power transistors, in the late 1980s.Available since the late 1980s IGBTs represent the back bone of inverters. Broad application in industrial automation was followed by automotive volume products from the early 2000s.
In the meantime, electrification technology has been adapted into off-road equipment. Agricultural tractors with higher power electric drive systems were introduced by John Deere with 7430/7530 E-Premium (2007) [2], Belarus’s model 3023 (2009) and Fendt with the X-Concept tractor (2013).
ELECTRIC DRIVE SYSTEM ARCHITECTURE
In current mobile applications, the common source to power an electric generator is a combustion engine. The generator is either mechanically linked to the crankshaft directly or via a transmission (see Figure 2)
In order to compensate for changes in rotational speed and therefore in output voltage and frequency of the generator, a first inverter is applied. Out of this DC-link, a second inverter, dedicated to the load, is applied to power the electric motor. This motor is driving a load either directly or via a transmission or gear set. The architecture is well established and introduced in various on- and off-road applications, e.g. [4]..
Electric drive system, schematic
VOLTAGE LEVELS, INTERFACES AND STANDARDIZATION
If power needs to be provided to agricultural implements on a 12V level, ISO 1724 connectors, the standard interface for lights and the ISOBUS Connector (see ISO 11783), a combination of a CAN-
based data interface and a 60amps capable power interface are applied.
The overall power available for implements out of the legacy 12V system is principally limited by the capabilities of alternators and the electric current required. Since the electric current drives the
ICPC 2019 – 3.4
94
conductor size and therefore weight, space and costs of an electric drive system.
In general, for mobile machinery applications, two voltage classes are considered:
Class A <50VAC; <75VDC, covering 12/24V systems as well as the new 48 V systems
and Class B 50VAC…1000VAC; 75VDC…1500VDC
Class B voltage covers the mainstream of electric and hybrid drive systems currently present in the marketplace for vehicles and mobile machinery. Respective requirements are basically covered by the “low voltage directive” (2006/95 EC). Since the term “Low voltage”, defined relative to cross country power lines, is easily misunderstood, the automotive industry is commonly using the term HV “Hochvolt” or “Higher Voltage” to characterize systems beyond the common 12V/24V onboard systems.
Geometry and performance of an interface to transfer class B power from tractors to implements has been described by the AEF (Agricultural Electronics Foundation). The respective AEF guidelines represent the foundation of standardization activities currently in process as ISO 23316: Electrical high-power interface 700VDC/480VAC.
Triggered by first class B applications on tractors having entered the marketplace, a safety standard has been released, ISO 16230:
New 48 V systems first introduced by the automotive industry are becoming attractive to off-road applications due to their cost effectiveness and component availability. They are very likely going to be an option for intermediate power levels, e.g. 2 … 20 kW, on board of tractors and on implements. Safety focused standardization is ongoing, working on the draft for ISO 23285.
48 V systems are not in focus of the current paper.
TRACTOR/IMPLEMENT TRACTION DRIVE SYSTEMS
Tractive performance of agricultural tractors is a function of the force between the tire and soil. The ballasted tractor weight is the major factor contributing to this force. Ballast and weight transferred from implements add additional force to the tires.
A current technology 400HP 4WD tractor (appr. 295kW) requiring a weight of about 27.6 tons to
efficiently deliver draft at 10 km/h field speed represents a benchmark.
With the new technology, electric traction assist on implement axles, transferring about 100HP electrical power from the tractor to an implement and using the implement’s weight for the tractive force allows scaling down the tractor’s weight to 20.2 tons. The result is a combination of reduced soil pressure, increased payloads (based on system gross weight regulations). An additional opportunity comes via the electrical power bypassing the tractors drivetrain on its path from the engine-driven generator to the implement’s traction assist axle – the provision of additional engine boost power becomes possible [4].
Based on complex simulation-based research in 2015, the value coming with electric traction assist has initially been validated in the field with a combination of a mid-size tractor and a slurry tanker. The power has been generated by a tractor front-PTO driven module [4].
Complementary field validation has been carried out in the subsequent years. In 2018 detailed field investigations were done based on a current John Deere 8400R and a Joskin slurry tanker equipped with an electric traction assist system. This system contained the key components, the “Traction Kit”:
• Off-the-shelve truck axle with differential
• JD Power systems gearbox
• JD modular high power-density electric motor
• AEF-HV-interface compatible power harness The field experience made transparent that a significant increase of productivity was made available thru the capability to pull wider injection tools behind a given tractor. Compared to current technology systems and using an exemplary farm operation as a base for calculations, productivity increases beyond 20 % were demonstrated. The corresponding revenue increase comes with
• about 15 % reduced machine operating costs,
• improved uphill and sidehill driving,
• optimized guidance performance, and
• less soil damages. To support the development of agricultural implements with traction assist features, John Deere Power Systems has introduced the “Traction Kit” at the 2019 BAUMA at Munich, Germany. To complement the electric machine and the gearbox with power electronics, John Deere Electronic
ICPC 2019 – 3.4
95
Solutions makes an inverter portfolio accessible to the industry.
SUMMARY
In the same way mechanical PTO and hydraulics led to increased productivity of agricultural machinery and particularly tractor/implement systems by allowing greater flexibility in implement design and introducing complex implements, electrical power systems are leading the way to increased options for process control and automation. Power can be transferred to remote regions of the implement where there may not be space to route hydraulic lines.
The key building blocks to deliver electric drive systems on Ag machinery, technology, safety measures, components and interface standard are available to the industry.
Implement traction assist systems are a great example to demonstrate the value coming with electric drives’ enhanced control and power distribution capabilities.
“Slower but wider, without tractor weight increase” is leading the way to a new generation of integrated high-performance tractor-implement systems.
Key components needed for electric drive solution are becoming available thru John Deere Power Systems’ traction kit and John Deere Electronic Solutions’ portfolio of power electronics - The Next Generation is at the door.
REFERENCES
[4] [1] Electric drives in mobile agricultural machinery – products and potentials, Dr. Joachim Sobotzik, ICPC 2013, Graz/Austria, 2013
[5] [2] E-Premium: Höhere Spannung in landwirtschaftlichen Nutzfahrzeugen, Dr. Eckhard Buning, Thilo Kempf, Roger Keil, VDI Tagung Landtechnik, Hohenheim, 2008
[6] [3] Dieselelektrisches Antriebssystem in selbstfahrenden Arbeitsmaschinen, T. Herlitzius, W. Aumer, M. Geißler, M. Lindner, 4. Fachtagung Baumaschinentechnik, Energie, Ressourcen, Umwelt, Dresden, 2009
[7] [4] Electrification as Enabler for New Tractor-Implement Solutions. Smart power system for implement traction drives and process drives, Dr. Rainer Gugel, Dr. Barbara Böhm, VDI Tagung Landtechnik, Hannover, 2015
STANDARDS
ISO23316 (in process) -Electrical high-power interface 700VDC/480VAC
ISO 16230 -Agricultural machinery and tractors – Safety of higher voltage electrical and electronic components and systems
ISO 23285 (draft)- Tractors and machinery for agriculture and forestry – 32-75 VDC Systems for Ag and EMM
96
ICPC 2019 – 4.1
The initiative of the AG machinery industry for CO2 emission reduction
Dr. Eberhard Nacke, Patrick Ahlbrand
Claas KGaAmbH
Copyright © 2019 AVL List GmbH, Claas KGaAmbH and SAE International
INTRODUCTION
Various interest groups or political parties may question the relevance of human influence in respect to climatic change. However, the majority of the scientific community is convinced that there are means to counteract global warming. Fighting against climatic change becomes a responsibility of any branch of our economies, notwithstanding that there may be other sectors, which represent a much higher share of climate relevant emissions..
It is a fact that a continuously growing world population will starve from hunger if agriculture will not increase its productivity by 50 – 100% within the next 30 years. Still, the agricultural sector is as well responsible as a major source of climatic gas emissions.
Therefore, success depends on the optimal combination of emission reduction and the preservation and expansion of productivity in agriculture. We have to foster innovations in agriculture to match both objectives. However, innovations do not arise in a regulatory environment, but rather in a competitive environment.
Over the past two decades, manufacturers of cars, trucks and mobile machinery have devoted a great part of their R&D investments into the implementation of exhaust gas regulations for engines with the aim of a drastic reduction of particulate matter and hazardous nitrogen oxide emissions. As a downside of this general focus on engines of entire industries, many other innovative developments, which do have positive effects on efficiency and emissions, have fallen by the wayside.
Now, as we concentrate on climatic gas, a comparable approach to reduce CO2 emissions of engines is conceivable. Nevertheless, the result will most likely be extremely limited in its impact if we do not want to risk what we have achieved in terms of NOx and particle emissions.
Within the agricultural sector, machinery are only responsible for a small proportion of total emissions. Notwithstanding, the AG machinery industry is ready to take its share of the responsibility for our climate. Despite the fact, that the engine exhaust emits CO2, there are many more means to reduce CO2 than just engine optimization, Figure 1..
Figure 1 CO2 efficiency potential
ICPC 2019 – 4.1
97
Holistic Approach
The agricultural mechanization industry is asking for a holistic approach to reduce emissions. Although climate-damaging emissions result from engine exhaust, it does not really make sense to look at the engine and its potential alone. A tractor emits CO2, but the very reason is the emission is the implement, which the tractor may be towing behind. The main potentials lie in all the aggregates of a machine and in the respective agricultural processes such as tillage, sowing, crop protection, fertilization and harvesting. The combination of tractor and implement is significant, whose harmony promises substantial savings.
Even an isolated view at an individual tractor-implement combination may be misleading, as a reduction in a first process may call for more emissions in consecutive steps. We have to regard entire mechanization process chains to reach our objectives sustainably. Indeed, agriculture is differing from almost all other sectors as we are working in an environment, which we cannot standardize. Shape of the landscape, differing soils, and varying
temperature, humidity and solar radiation call for a very individual and site-specific optimization of mechanization processes. If a farmer has to follow static rules and restrictions neglecting the specific situation on his site, we will end up in a big loss in efficiency and as well, we will not exploit the full potential of emission reduction
Machine and machinery chain improvement may provide opportunities, but proper realization is mostly dependent on the human factor, being the driver of the machine. Reducing driver’s vulnerability to run a machine ineffectively in respect to emissions is one of the major sources to fight climatic gas emissions in Ag mechanization.
The EkoTech project
Under the umbrella of VDMA, a consortium of major AG machinery companies and related research institutions are collaborating in the project “EKoTech – Efficient fuel use in agricultural technology”, with the objective to initiate a movement in the entire industry, Figure 2.
Figure 2 Project team
Figure 3 4-pillar approach of the European Manufacturer associations CECE and CEMA
ICPC 2019 – 4.1
98
A movement to take responsibility in a joint fight for fuel efficiency and against climatic change by utilizing the entire innovative power of Ag engineering instead of reducing it to a narrow regulation based compliance to a single threshold.
The research project, funded by the German Ministry of Agriculture, involves well-known manufacturers and research facilities. The close collaboration between industry, science and advisory institutions ensure a broad and comprehensive view at farmer’s options in the future.
The structure of the research project is based on the 4-pillar approach of the European Manufacturer associations CECE and CEMA: CO2 potential in terms of machine efficiency, process efficiency, improvement of operator performance, and potential of alternative energy sources (Figure 3).
Looking at savings potential in entire process chains instead of concentrating just on engines gives room for improvements in many directions. Respecting the real world in farming or anywhere else, another factor
often tends to be inefficient - the human factor. Machinery and process designers may find substantial improvements, but if the operator is not well trained or just has more fun using machines inefficiently, our contribution in the fight against climate change will be minor.
Arable production is characterized by different machinery processes throughout the year, being adapted to the specific needs of an individual site (Figure 4). Reducing emissions could be easy: do less. Reducing intensity of work or even omitting some of these process steps will definitely reduce CO2 emissions. However, if reducing emissions leads to a decline in productivity, we have achieved nothing. The very sense of farming is production, and any improvement in terms of fuel consumption has to be related to the quantity and quality of food or forage produced. Consequently, it does not make sense to identify CO2 emission progress per machine or hectare. The only valid measure can be CO2 emission savings per ton of grain or grass produced [l/t].
Figure 4 EKoTech - Agricultural Process Chains
The research project develops the basic methods for implementing this concept. Region-typical model farms are identified and their location and crop rotation-specific process chains (wheat, maize, and grass) mapped in a simulation model. They form the basis for the investigation of reduction potentials. Due to the nature of farming in an environment, which cannot be standardized, the simulation approach provides best means to acknowledge reality, but still
quantify the potential of the AG machinery industry in prevailing crops and typical farming regions.
There are many opportunities, but we need to reconcile the need for emission reduction and productivity growth. EkoTech shows that promoting competition is the best way to provide a CO2 efficient solution.
99
ICPC 2019 – 4.2
Long haul truck powertrain control for low emission and fuel consumption in real traffic conditions
Alois Danninger
AVL List GmbH Copyright © 2019 AVL List GmbH and SAE International
ABSTRACT
Fuel efficiency and emissions reduction interact with each other and vary with the specific vehicle application, operating conditions and mission. The pre-condition for predictive vehicle control is the knowledge on future velocity profile. Within the IMPERIUM [1] project a dynamic eHorizon system is developed and applied in 3 different trucks with a “look ahead” capability of delivering static, learned and dynamic data with respect to the road ahead. The measures for fuel consumption reduction combine conventional, rule based and/or predictive implementations. These are engine and EAS control, hybridization, thermal management and global powertrain and vehicle supervisor. A mission- and model- based validation of improvements based on simulation including realistic traffic scenarios is implemented.
INTRODUCTION
In the transport sector, the reduction of real driving emissions and fuel consumption in long haul traffic is one of the main societal challenges. Regulations e.g. Euro VI are a baseline with respect to targets in defined test environment conditions, while a clear need exist to have real driving efficiency measurements to promote the introduction of innovative solutions for fuel consumption and emission reductions.
Fuel efficiency and emissions reduction interact with each other and vary with the specific vehicle application, operating conditions and mission. The overall objective is the development of new means of predictive and comprehensive powertrain control in an optimal way, exploiting to the full potential of the individual systems for each vehicle application and mission.
The pre-condition for predictive vehicle control is the knowledge on future velocity profile. Within the
IMPERIUM project a dynamic eHorizon system is developed and applied in 3 different trucks with a “look ahead” capability of delivering static (topology, speed limits, curve radii …), learned (truck behavior) and dynamic data (speed limit changes, traffic flow, construction sites, incidents, local weather…) with respect to the road ahead [2].
The measures for fuel consumption reduction are grouped into 4 clusters with each combining conventional, rule based and/or predictive implementations:
• Engine and EAS control
• Hybridization
• Thermal management
• Global powertrain and vehicle supervisor
This contribution presents selected outcomes with respect to fuel consumption reduction of the EU-funded 3-year research program IMPERIUM and therefore gives a glance on upcoming technologies for CO2 reduction under real driving conditions and attractive from a Total Cost of Ownership perspective in commercial vehicle transport.
ENERGY MANAGEMENT SYSTEM
The task of the energy management supervisor controller is to suggest a driving strategy, as well as a control strategy for whole powertrain and its components like combustion engine, electric motor, battery, transmission or auxiliaries. The driving strategy is to a significant extent derived from information of the road ahead and from information about other traffic participants. The main objective of developed driving strategy is reduction of fuel consumption and emissions by simultaneously ensuring reasonable journey time and driver acceptance criteria.
In theory, this would lead to an extremely complex optimization problem for the whole vehicle including
ICPC 2019 – 4.2
100
component details with many degrees of freedom. Such optimization problems are according to current state of the art not possible to solve faster than real-time while driving.
One possibility to overcome this issue is to break the complex optimization problem into several smaller optimization problems (sub problems) for e.g. different system levels, components, etc. These sub problems can be solved fast with acceptable accuracy. This approach relies on the assumption, that the solutions of all sub problems can be realized in parallel, and that they lead to a solution, which is reasonably close to the global optimum.
Therefore, the key lies in the identification and formulation of appropriate smaller problems that fulfill above mentioned assumption. The formulation must
consider that the combined solution of the sub problems approximates a global optimum reasonably well. Looking at the overall system structure (see Figure 7) gives valuable insights in how the formulation of the sub problems may look like. It is shown that all relevant powertrain components, such as engine, Exhaust After-treatment System (EAS), transmission, battery and electric motor have a direct connection to the powertrain controller. Additionally, the velocity optimizer exchanges the predicted load profile with the powertrain controller. In other words, in the powertrain controller all relevant information related to the overall optimization problem is available.
As stated above, solving the overall optimization problem directly and in real time is currently not possible with known state of the art methods.
System Structure
The powertrain controller coordinates all information exchange between powertrain components and the velocity optimizer. Exchanged information contains predictions about the future vehicle states (e.g. expected load, expected gear, ...). The predictions are tailored to the needs of each component. Components can use the predictions to compute optimal operation strategies for themselves.
It is important to note, that if each component only computes the best operation strategy for itself, these strategies may be conflicting (e.g. EAS needs a higher engine load to increase exhaust gas temperature, but the velocity optimizer needs to slow down because of a preceding vehicle). Therefore, each component provides alternative strategies in addition. The powertrain controller coordinates the possible “search range” of all components to reduce the number of contradicting strategies. An “efficiency factor” or “cost” is assigned to each strategy, giving an indication about the loss of efficiency for that component, if an alternative strategy is used.
Based on the collection and evaluation of all optimal and alternative operation strategies that the components and the velocity optimizer provide, the best overall strategy is selected based on a parameterizable cost function. Information exchange between the components is updated according to the selected strategy.
The overall optimization problem can be solved based on the solutions of several sub problems on component level.
The overall costs are specified by the cost function:
𝐶𝑔,𝑣,𝑒,𝑎,𝑡 = ∑ 𝐿𝑔,𝑘 +
𝑁−1
𝑘=0
∑ 𝐿𝑣,𝑘 +
𝑁−1
𝑘=0
∑ 𝐿𝑒,𝑘 +
𝑁−1
𝑘=0
∑ 𝐿𝑎,𝑘
𝑁−1
𝑘=0
+ ∑ 𝐿𝑡,𝑘
𝑁−1
𝑘=0
𝑘 corresponds to discrete points in time, 𝑘 𝜖 𝑁+.
ICPC 2019 – 4.2
101
𝑁 refers to the length of the prediction horizon, 𝑁 𝜖 𝑁+.
𝐿𝑔,𝑘 refers to the cost of the gearbox (friction losses
and potential loss of travel time), at time 𝑘 if the gth strategy is applied; 𝑔 = 1, 2, … 𝐺, whereas G is the number of investigated strategies in for the sub-optimization problems of the gearbox / transmission.
𝐿𝑣,𝑘 refers to the cost of the velocity optimizer (energy
required on vehicle level), at time 𝑘 if the vth strategy is applied; 𝑣 = 1, 2, … 𝑉, whereas V is the number of investigated strategies in the sub-optimization problems of the velocity optimizer.
𝐿𝑒,𝑘 refers to the cost of the engine (fuel consumption,
emissions), at time 𝑘 if the eth strategy is applied; 𝑒 =1, 2, … 𝐸, whereas E is the number of investigated strategies in for the sub-optimization problems of the engine.
𝐿𝑎,𝑘 refers to the cost of the EAS (e.g. AdBlue
Consumption), at time 𝑘 if the a-th strategy is applied; 𝑎 = 1, 2, … 𝐴, whereas A is the number of investigated strategies in for the sub-optimization problems of the EAS.
𝐿𝑡,𝑘 refers to the cost of the thermal system (e.g.
increased aerodynamic losses if grill shutter is open, or power consumption of pumps), at time 𝑘 if the tth strategy is applied; 𝑡 = 1, 2, … 𝑇, whereas T is the number of investigated strategies in for the sub-optimization problems of the thermal system.
𝐶𝑔,𝑣,𝑒,𝑎,𝑡 is the overall cost as a combination of the
individual operation strategies as determined by the individual subsystems / components.
Note that as explained above some of the combinations of individual strategies in 𝐶𝑔,𝑣,𝑒,𝑎,𝑡 may
be contradicting each other and therefore must be omitted. However, as the powertrain controller takes care to coordinate the potential range of individual solutions. The remaining, implementable combinations are summarized in �̃�𝑔,𝑣,𝑒,𝑎,𝑡. The cost of
the optimal strategy 𝐶𝑚𝑖𝑛 and the corresponding indices of the individual sub strategies on component level 𝑔, 𝑣, 𝑒, 𝑎 and 𝑡 can then be determined by
𝐶𝑚𝑖𝑛 = 𝐦𝐢𝐧𝒈,𝒗,𝒆,𝒂,𝒕
�̃�𝑔,𝑣,𝑒,𝑎,𝑡
VELOCITY OPTIMIZER
The velocity optimizer ensures the best use of kinetic energy. For example, if a vehicle drives downhill, and if it is known, that another uphill part will follow immediately, the vehicle could increase the velocity,
exceed the normal target velocity within legal limits and consequently increase its kinetic energy just by reducing the braking forces, see Figure 8. The increase in kinetic energy will be used in the subsequent uphill part, and therefore the required engine power as well as the fuel consumption can be reduced. Thus, a key aspect for fuel consumption reduction is the computation of an optimal vehicle velocity profile. This is done by the velocity optimizer.
Velocity Optimizer
The velocity optimizer suggests an optimized velocity profile based on available information within the so-called eHorizon of the road ahead. Based on this velocity and power profile, other optimizers e.g. the powertrain optimizer compute their optimal strategies.
Target of the velocity optimization is the reduction of the overall required energy, which can be measured in total fuel consumption (e.g. Diesel & AdBlue) and battery state of charge. Also, aspects like thermal energy management or EAS will be considered. Due to time constants for thermal measures, which are in the range of approx. 10 minutes, a velocity profile for this upcoming time interval is required.
The information of the road ahead is available within the eHorizon. Thus, the velocity profile can rely on quantities like, e.g.:
• Current position or velocity,
• Road type (e.g. class, number of lanes, bridge/tunnel),
• Road information (e.g. curvature, crossroads),
• Altitude and inclination,
• (Legal) Speed limits,
• Traffic information (e.g. traffic density or average speed of traffic, traffic jams).
Consequently, based on legal speed limits, average traffic velocity, curvature and other information, an effective speed limit can be estimated, i.e. a maximum realizable velocity by the vehicle, which is one boundary condition in the optimization.
In real life the optimal velocity with respect to fuel consumption would be at a very low velocity. The faster a vehicle is driving, the higher is the fuel consumption due to increased driving resistance and air drag. Thus, additional boundary conditions with respect to a minimum required velocity as well as to journey time must be considered.
ICPC 2019 – 4.2
102
Solving the optimization problem on the vehicle while driving requires an optimizer, which is much faster than real time. A two-step approach is implemented to overcome this issue. At first, based on a vehicle model which contains simplified engine and transmission control strategies, the optimal velocity profile is computed for a catalogue of different representative driving maneuvers combined with altitudes. Secondly, based on these simulations and gained insights, another real-time capable control is derived, which results in a close to optimal velocity profile for any arbitrary driving scenario. The real-time capable control is implemented in the “velocity optimizer” onboard.
Velocity change requests can come from other optimizers, which use the velocity profile as basis, (e.g. in a thermal optimization loop a higher velocity could be more convenient) or from adaptive cruise control, for example if another slower vehicle is detected by the radar, see Figure 9. The velocity change request needs to be combined with an efficiency factor or cost. The velocity optimizer can now estimate what following the velocity change request would cost in terms of fuel consumption, and it can update its velocity profile based on this value as well as on the priority.
Velocity Optimizer connection to adaptive cruise control.
The predictions and suggested velocity profile are made available to the Powertrain Controller and all other subsystems or components (e.g. engine, transmission control) that may use this information to make predictions and optimizations of their own. The velocity optimizer provides the following information:
• Predicted vehicle velocity trajectories,
• Selected vehicle velocity trajectory,
• Current velocity request,
• Eco-roll request (e.g. if neutral gear is requested)
ECO-ROLL
Eco-roll is a measure to balance mission time with energy consumption. It contains an online optimization method that automatically finds optimal drive mode sequences for specific situations, which predictive cruise control may not handle on its own.
Eco-roll is running on standby while predictive cruise control is active and constantly looks for specific events. Such an event may be the detection of a preceding vehicle, which requires a specific action (e.g. reduce the velocity in a specific way to follow the preceding vehicle at the same speed at a desired distance). Another example for an event may be the detection of an upcoming curve, for which the velocity also must be reduced in a specific way. Eco-roll in general is not limited to situations where the velocity at the end is lower than at the beginning, though such cases may occur more frequent.
If an event is detected by Eco-roll, targets for the velocity, covered distance and travel time are computed. For the example of approaching a curve, that means that the velocity at the beginning of the curve is defined by the “safe cornering speed”, the distance is specified by the position of the curve and the travel time is constrained by a driver’s acceptance criteria (drivability) and deceleration limits. A real-time capable algorithm then finds the optimal (in terms of fuel economy and travel time) sequence of modes tailored to the current driving situation. Figure 10 shows an example of a scenario for which Eco-roll is used.
Exemplary scenario for Eco-roll.
PREDICTIVE GEARSHIFT
The Predictive Gearshift Module (PGS) provides gear shift suggestions based on the eHorizon road profile and the optimized vehicle speed from the velocity optimizer. A major aim of predictive gearshift (amongst other such as improvement of fuel consumption) is avoiding drops of the vehicle velocity on uphill sections. Therefore, the up- and downshift commands should comply with hysteresis and dynamic requirements for driving on flat road, uphill and downhill as well as engine speed limits.
The PGS module receives information from the eHorizon (e.g. road type, altitude, inclination, speed limits, traffic information, …) as well as an optimized velocity profile from the velocity optimizer.
In addition to the functionality for the basic shifting strategy, the PGS calculates costs for possible gear
shifts scenarios, which are relevant for the powertrain controller.
ICPC 2019 – 4.2
103
These costs consider following aspects:
• Gear box efficiency
• Comfort
• Number of gearshifts (especially during uphill)
• Foresight shifting
• Deviations from the received target vehicle speed
• Travel time (based on driver requests)
Gear shifts during uphill driving may lead to very high costs, whereas shifting on flat road or on slight slopes may increase the costs only marginally.
Possible shifting scenarios/modes of the PGS module are:
• Efficiency (max. gearbox efficiency)
• Comfort (acceleration and deceleration as low as possible)
• Balance (mix of Efficiency and Comfort)
• Dynamic (lowest possible gear, may be also required for predictive thermal control)
• EcoRoll-Light (highest possible gear, may be also required for predictive thermal control)
• EcoRoll (Neutral Gear – coasting mode)
The PGS modules calculate for each scenario a vector with decided gearshift positions and related costs. Therefore, predicted gears for at least two scenarios and the related cost is provided back to the powertrain controller.
MODEL PREDICTIVE ENGINE & EXHAUST AFTERTREATMENT CONTROL
The main task of the Model Predictive Engine Control within the energy manager is to provide cost factors for a set of possible engine load points (engine torque/speed). This information is used for the selection of the gear level and or powertrain strategy (e.g. E-Motor / engine torque split or load point shift) by the Powertrain Supervisor. The optimized request values contain the EAS heat up request, the optimized request value for tailpipe NOX mass flow and the optimized desired DOC upstream temperature.
Additionally, the gear information, torques & speeds are received from the Predictive Gearshift Module. For at least two predicted possible torque/speed pairs the corresponding engine and EAS optimizer calculates the corresponding cost functions.
The main outputs are the engine / EAS system total costs [g/kWh] or normalized cost factor and the velocity offset request to velocity optimizer and EAS heat up request (time based vector over prediction
horizon). Further on the desired tailpipe NOX mass flow, desired DOC upstream temperature and an EAS heat up request are provided.
Optimization problem
The main trade-off parameters for the engine / EAS system which need to be considered and optimized towards lowest operation costs which keeping compliant with emission limits are:
• NOX / Total Fuel Consumption (Diesel & AdBlue) trade off;
• EAS thermal management: Tailpipe NOX versus engine out temperature as main influence on SCR efficiency;
• Cooling actuator power versus engine mainly influenced by intake manifold temperature and EGR temperature;
• Thermal management / engine coolant circuit: Power/Temperature engine coolant circuit versus ICE fuel consumption & BSNOX
NOX / Soot tradeoff is considered as not critical for the considered application.
Cost Function design for optimized predictive engine operation
For the engine cost function primarily, the consumption of Diesel and AdBlue is considered.
Additionally, a too low exhaust temperature will be penalized as a constraint, whereas only a negative deviation to a minimum temperature threshold will affect the cost function. The temperature threshold depends on the SCR efficiency. Furthermore, the NOX emissions are considered also as a constraint, a deviation to a maximum allowed limit value will be penalized.
The modelled consumption of Diesel and AdBlue are accumulated over the prediction horizon to derive the consumed masses, which then are multiplied with the price per mass. Furthermore, other relevant system states are modelled/predicted ahead, like engine out temperature and temperatures along the EAS path, which are then considered in the cost function J. The optimization is done iteratively, calculating / modelling the relevant states for each considered variation along the prediction horizon.
Following input parameters are varied and the corresponding cost functions are calculated:
• Engine speed / torque pairs (load points) trajectories for the preselected gear level sequences in a pre-optimization loop
ICPC 2019 – 4.2
104
• EAS temperature and Engine Out NOX in a 2nd optimization loop
The boundary condition of exhaust gas temperature to be as low as possible, but as high as necessary to ensure SCR efficiency needs to be respected. An online tailpipe NOX observer ensures compliance with real life emission limits e.g. the In Service Conformity regulation.
𝐽𝑀𝑖𝑛 = 𝑚𝑖𝑛{C𝑑𝑖𝑒𝑠𝑒𝑙 + C𝑎𝑑𝐵𝑙𝑢𝑒 + max(0, NOx − NOxLim)− (min(TScrLim, TScr) − TScrLim)∙ PTDevScr}
𝐽𝑀𝑖𝑛 Overall engine / EAS cost function
C𝑑𝑖𝑒𝑠𝑒𝑙 Cost Diesel (accumulated mass Diesel multiplied by price per mass)
C𝑎𝑑𝐵𝑙𝑢𝑒 Cost AdBlue (accumulated AdBlue mass multiplied by price per mass)
NOxLim NOX Limit, an exceeding of this limit will be penalized
TScrLim SCR temperature limit, temperature level below will be penalized by the cost function
PTDevScr Price or penalty factor when SCR temperature falls below limit
VALIDATION
The main challenge to judge the fuel consumption reductions achieved is that a significant proportion of the expected benefit related to technology improvement will be in real-world traffic conditions, which can be anticipated due to the electronic horizon infrastructure. It is expected that the vehicle’s electronic controllers will be able to handle upcoming traffic situations more efficiently than a manual driver, who is not aware of upcoming issues on the route until they enter the line-of-sight.
The only option to get reproducible traffic needed for the validation is to use a simulation environment. A further challenge of validation under reproducible traffic conditions is, that even in simulation, the simulated traffic itself develops an interaction with the simulated vehicle under test.
Some key points that that were learnt from this activity are:
• each simulation is deterministic and therefore perfectly reproducible, but;
• a small change in the full load curve of the engine or in the vehicle control strategy has a strong influence on the vehicle’s trajectory through the traffic jam, even if all the other parameters of traffic simulation are kept the same.
The VECTO Long-Haul CO2 assessment cycle is used as a basis for assessment. The specific cycle definition used here is from VECTO 3.3.0.125 [3]. The loading condition used was the Long-Haul Reference Load (RL-LH). This load condition assumes a 19300kg payload and 7500kg trailer in addition to the tractor mass. The VECTO Long Haul cycle is defined as four vectors of distance, gradient, velocity target and stop duration.
Traffic is added to the simulation environment by means of traffic micro-simulation, which employs agent-based modelling to produce naturalistic traffic flow patterns. Each vehicle in the simulation obeys a set of rules that govern the vehicle and driver’s behavior with respect to the other vehicles in the simulation. As each vehicle interacts with the surrounding vehicles, complex traffic flow patterns emerge, such as congestion and traffic jams. The SUMO (Simulation of Urban Mobility) [4] simulator and TraCI4Matlab [5] are used in the results presented here.
RESULTS
Currently the measurement initiative is ongoing to validate the results on demonstrator trucks in real driving conditions. For this initiative the algorithms are implemented in prototype control units for online testing.
To judge the output of the simulation results and the fuel consumption improvement compared to the baseline uses the following equation:
𝐹𝐶𝑟𝑒𝑙[%] =FC
[l]Distance[100km]
FCRef [𝑙
100𝑘𝑚]
∗ 100 [%]
As simulated traffic is included, interactions between the vehicle under test and the traffic will influence the fuel consumption result. Therefore, the statistical nature of the results must be considered.
When simulated under traffic conditions on the IMPERIUM Long Haul cycle, the fuel consumption reduction incorporating the described technologies is calculated with -5.1 %.
CONCLUSION
The global powertrain optimisation takes care about power, propulsion, thermal system and pollutant emissions. The outcomes are globally optimised set values for the powertrain elements like internal combustion engine, transmission, thermal system, waste heat recovery, battery and e-motor.
ICPC 2019 – 4.2
105
The use of predictive information in the traditional powertrain domain, especially the combustion system enables further improvements.
The dependency on traffic directly leads to the problem of non-reproducible validation measurements on real roads. Therefore, a simulation – based validation strategy is developed.
It can be concluded that fuel consumption increases by circa 10% under the studied ‘real traffic’ conditions. The changes in vehicle control considering upcoming road inclinations and the dynamic electronic horizon data stream lead to reductions in fuel consumption by up to 5.1 %, particularly in case of increased traffic.
DEFINITIONS, ACRONYMS, ABBREVIATIONS
DOC Diesel Oxygen Catalyst
EAS Exhaust Aftertreatment
EGR Exhaust Gas Recirculation
PGS Predictive Gear Shift
REFERENCES
[1] A. Danninger, N. Knopper and E. Armengaud, "Welcome to the IMPERIUM project," 2019. [Online]. Available: http://www.imperium-project.eu. [Accessed 01 04 2019].
[2] A. Danninger, E. Armengaud, G. Milton, J. Lützner, B. Hakstege, G. Zurlo, A. Schöni, J. Lindberg and F. Krainer, "IMPERIUM – IMplementation of Powertrain Control for Economic and Clean Real driving emIssion and fuel Consumption," in 7th Transport Research Arena TRA, Vienna, 2018.
[3] "Vehicle Energy Consumption calculation TOol - VECTO," European Commission, 2018. [Online]. Available: https://ec.europa.eu/clima/policies/transport/vehicles/vecto_en.
[4] D. Krajzewicz, J. Erdmann, M. Behrisch and L. Bieker, "Recent Development and Applications of SUMO - Simulation of Urban MObility," International Journal On Advances in Systems and Measurements, vol. 5, pp. 128-138, 2012.
[5] A. F. Acosta, J. E. E. Oviedo and J. J. E. Oviedo, "TraCI4Matlab: Enabling the Integration of the SUMO Road Traffic Simulator and Matlab® Through a Software Re-engineering Process," in Modeling Mobility with Open Data: 2nd SUMO Conference, Berlin, Germany, 2014.
ACKNOWLEDGMENTS
The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement n° 713783 (IMPERIUM) and from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract n°16.0063 for the Swiss consortium members. The paper represents cooperative results from the consortium consisting of the following partners:
Special thanks go to Ferdinand Krainer and Marc Seljak who intensively worked on this topic and provided the basis for this contribution.
106
ICPC 2019 – 5.1
Impacts of Digitalization on the Ag Industry
Dr. Markus Baldinger, Dr. Martin Follmer
Pöttinger Landtechnik GmbH Copyright © 2019 AVL List GmbH, Pöttinger Landtechnik GmbH and SAE International
ABSTRACT
Digitalization enables major changes and improvements in agricultural industry. Implements, tractors and the farmers office are going to work more closely together. Various data are produced by each machine involved in the process chain and are combined with sensor data from e.g., weather stations, satellites and drones. Furthermore, sophisticated mathematical models (e.g. based on historical data and forecasts) are used to optimize the processes and to support the farmer in decision making. The combination of all these data and the enrichment with artificial intelligence offers the possibility to gain a holistic view on agriculture and to establish new services as well as business models.
Also several demanding challenges came up with digitalization for both manufacturer as well as end customer. Manufactures have to establish new competences in the whole organizations and have to find new partners to handle the new technologies. End customers have to deal with data platforms and data security, farm management systems and also new technologies on their machines.
Digitalization offers manifold potentials to optimize the processes, to increase productivity and to make agriculture more sustainable.
DIGITALIZATION IN AG INDUSTRY
Agriculture 3.0 – Precision Farming – started once military GPS-signals were made available for public use and offers solutions for guidance (mid-1990s), sensing & control (during the 1990s), telematics (early 2000s) and data management (early 80s). The intention is to give each plant exactly what it needs to grow optimally, with the goal to optimize the agronomic output while reducing the input (‘more with less’) [1].
Agriculture 4.0 – Smart Agriculture or synoym also called Digital Farming – started in the early 2010s based on the evolution of several technologies: cheap
and improved sensors and actuators, low cost micro-processors, high bandwidth cellular communication, cloud based ICT systems, big data analysis. Agriculture 4.0 stands for the integrated internal and external networking of farming operations. This means that information in digital form exists for all farm sectors and processes; communication with external partners such as suppliers and end customers is likewise carried out electronically; and data transmission, processing and analysis are (largely) automated. The use of internet-based portals can facilitate the handling of large volumes of data, as well as networking within the farm and with external partners [1].
Agriculture 5.0 is the synonym for the next evolution of farming consisting of unmanned operations and autonomous decision systems. Agriculture 5.0 will be based around robotics and (some form of) artificial intelligence [1].
Agriculture is a global business whose primary goal is to feed 10 billion people in 2050. All of these technologies make a contribution to the achievement of the goal through using resources more efficiently, being more animal-friendly, enable a sustainable production of high-quality food and optimize working processes [2].
Also [3] describes the huge potential of digitalization in Ag industry and claims the possibility of a tech-driven improvement of crop yields of up to 70% by 2050 using the following key technologies: a fleet of smaller autonomous systems to reduce compaction, precision fertilizer, precision irrigation, precision planting, precision spraying and several other technologies (e.g., field monitoring, data management). The current situation shows 15-20% yield loss suffered from inadequate fertilizer application and in turn a potential of 50% reduction in water waste by using modern irrigation systems.
ICPC 2019 – 5.1
107
KEY TECHNOLOGIES
According to [3] industry experts have the understanding that precision fertilizer applications will lead to 18% increase in yields. This can be achieved by collecting and analyzing several data e.g., weather data, soil data, drone and satellite data as well as previous yield data in combination with special hardware components (variable rate application). The data can be used to generate a map which allows for a subarea specific output quantity of fertilizer. Precision planting applications enable subarea specific seeding rates which will lead to 13% improvement in yields [3]. This can be done using multi-seed planters which allows to combine properties of different seeds in one planting or variable rate planting based on the specific subarea. Based on technologies such as image processing and highly accurate solenoid nozzles precision spraying applications will lead to approximately 4% improvement in yields [3]. This can be achieved by a subarea specific spraying rates. According to [3] precision irrigation is another promising technology which will lead to 10% improvement in yield and offers the potential to reduce water consumption by 50% [3]. A very important enabler for the technologies mentioned above is field monitoring using satellite, drones, weather data and models as well as remote soil sensors.
At present, automation is also of great importance in Ag industry and is being investigated intensively by both companies and research institutes. In recent years small autonomous systems which operate in so called field-swarm as well as big and heavy full-scale autonomous tractors have been demonstrated. All systems have common intentions: increase precision, effectiveness and sustainablity, become more productive and reduce labor costs. Field-swarms offer the additional benefit to decrease the negative influences of soil compaction which is responsible for the soil’s ability to hold water, nutrients and air. In the past decades the size of tractors used for agriculture has increased continuously, motivated by the increase of effectiveness and the reduction of labor costs. As a consequence, weight and dimensions of modern tractors have reached levels which are close to prevailing limits of usability as well as legal frameworks. Through the use of a fleet of smaller tractors (field-swarm) experts expect a yield improvement of about 13% by reducing the amount of soil and roots crushed by heavy agriculture machinery [3]. Several approaches of field swarms have been presented in the recent years: very small units (Fendt Xaver [4]) as well as bigger units with a standardized 3m working width (Feldschwarm project [5]). Much of the efforts done for the development of autonomous cars is already transferred to agriculture. Restrictions, tools and methods (such as the levels of
automation [6]), hardware components (e.g., radar, LIDAR, camera) and software tools & data (e.g., image recognition, maps) developed for autonomous car technology is going to foster autonomous technologies in Ag industry. This profound basis has to be enhanced with agriculture specific use cases and features [7].
All the data generated by e.g., drones, satellites, different sensors and vehicles used in modern farms have to be handled with a professional data management or so called Farm Management Information Systems (FMIS). The required office work, field and fleet management as well as several feed working steps for livestock farming and outdoor work are supported by professional software tools. In combination with mobile devices the farmer is (in real time) well informed about all ongoing processes and working steps and is connected to all relevant data.
CHALLENGES OF DIGITALIZATION
An online survey [8] done with more than 2000 persons residing in Germany shows that the German population has increasingly moved away from agriculture and thus the level of knowledge about current agricultural production processes is reversed. Explaining the potential of the new digital technologies in terms of environmental protection and animal welfare, the majority of respondents responded favorably to modern digital technologies. Furthermore, the majority of respondents indicate an increasing quality of life of farmers.
Another survey [2] done with more than 500 farmers shows that 88% of respondents believe that digital technologies can increase resource efficiencies. By contrast, 52% believe that digitization itself is the biggest challenge, and 39% see the associated costs as the biggest challenge.
To demonstrate the potential of digitalization in Ag industry so called test fields are going to be established in Germany, Switzerland (Swiss Future Farm, already started) and Austria (Innovation Farms Austria). The test fields will focus on e.g., the development and testing of technologies on real farms and therefore under real conditions, connecting of various agricultural processes, testing of agricultural digital applications (Use Cases), definition of suitable data standards, assessment of benefits in economic, environmental and social terms, assessment of opportunities and risks in the areas of sustainability, animal welfare and resource conservation. Test fields are going to be established as a point of contact to demonstrate the new technologies, to show the benefits, to enable knowledge transfer and to make digitalization more tangible [9].
ICPC 2019 – 5.1
108
CONCLUSION
The amount of new technologies that will find their way into agriculture also requires a lot of different (technical) skills. This not only affect the end customers – i.e., farmers or contractors – but also the machine manufacturers and dealers as well as the relevant educational institutions. From the point of view of a implement manufacturer, more cooperation must be entered to be able to handle all these topics. From the development of special sensors to artificial intelligence to evaluate the generated data, to the programming of apps, all of these topics must be competently supervised in future. This will also lead to changes in already established internal organizational processes (e.g., product development process) as well as new organizational units and possibly also new business models.
REFERENCES
[1] CEMA: Digital Farming: what does it really mean?; 2017
[2] Digitalisierung in der Landwirtschaft; BayWa AG; 2018
[3] Precision Farming; The Goldman Sachs Group, Inc.; 2016
[4] Fendt: Wird Xaver die Welt ernähren?; Thiemo Buchner; 2018
[5] The Evolution of Tractor Implement Systems to Modular and Highly Autonomous Machine Systems (field-swarm); Thomas Herlitzius, Jens Krzywinski, Matthias Klingner; 2019
[6] SAE J3016: Levels of driving automation; 2019
[7] From manual driving to full autonomy: An approach to systematically define different levels of automation in agricultural engineering; Norbert Streitberger, Florian Balbach, Eberhard Nacke; 2018
[8] Gesellschaftliche Akzeptanz von Digitalisierung in der Landwirtschaft; Johanna Pfeiffer, Sebastian Schleicher, Andreas Gabriel, Markus Gandorfer; 2019
[9] HBLFA Francisco Josephinum: Innovation Farms Austria; Heinrich Prankl; 2019
109
ICPC 2019 – 5.2
ADAS and Autonomy for Trucks - A look into the future
Ozan Nalcıoğlu, Alper Tekeli, Güvenç Barutçu, Berzah Ozan
Ford Otomotiv AS Copyright © 2019 AVL List GmbH, Ford Otomotiv AS and SAE International
ABSTRACT
Each and every year, road transportation demand is increasing in order to meet the requirements of developing world conditions. With the increased number of freight vehicles in the traffic, utilization of advanced driver assistance systems enhanced with connectivity features bring substantial benefits on traffic safety, transport system efficiency and driver comfort. Ford Trucks are currently equipped with several ADAS functions and Connectivity technologies which strongly supports truck drivers’ needs and logistic sector.
On top of ADAS and Connectivity Technologies, Automated Driving on Highways & Confined Areas holds a great potential for truck business which is the leading mode of freight transportation. Harmonious development of vehicle automation, digitalization and infrastructure will pave the way for transfer hub model, combining Highly Automated Driving functions on “specific approved roads” & “confined areas” with remote fleet and transport management systems. Ultimately, a new end-to-end logistic ecosystem will be formed with the usage of highly automated trucks and electrified distribution trucks in interurban and urban areas, respectively.
Ford Otosan is actively involved in several research&development projects named OptiTruck, TrustVehicle, PRYSTINE and 5G-MOBIX related with Advanced Cruise Control, Tractor-Trailer Combination Parking, Platooning & C-V2X technologies which are planned to be introduced on future products, aligned with the new business models of the logistic sector.
INTRODUCTION
Statistics of EU transportation modals show that road transportation has the largest share of EU freight transport by %75 consistently for the last 5 years. [1] Taking the increasing demand on transportation & current modal splits into account, Automated Driving enhanced with Connectivity Technologies hold a
great potential for truck business. The main drivers of higher levels of automated driving are categorized as safety, efficiency,environmental concerns and comfort in “Connected Automated Driving Roadmap” of ERTRAC [2] which is published in 2019.
Ford Otosan focuses on automated driving of heavy-commercial vehicles primarily for long-distance transportation & confined area logistics which will shape the future logistic and transportation eco-system. The overall roadmap includes not only L1&L2 ADAS functions which will be implemented in short term, but also Level-3+ functions which will serve for different customer needs to bring efficiency and comfort in near future.
Ford Otosan’s automated truck driving roadmap is consistent with ERTRAC’s recent report considering the development paths & implementation timings of different levels of connected-automated driving functions on commercial vehicles.
DIFFERENT LEVELS OF DRIVING AUTOMATION ON TRUCKS
More and more advanced driver assistance system (ADAS) functions (L0/L1/L2) – which help with monitoring, warning, accelerating, braking and steering tasks- are being implemented on trucks in order to increase traffic safety and driver comfort, largely driven by regulations and customer interests.
Without a doubt, the recent regulation proposal of European Commission which is announced at the end of Q1-2019 will accelerate the implementation of new ADAS functions on trucks.
Available ADAS Functions on Trucks
Driven by regulations, traffic safety and driver comfort, current trucks are mainly equipped with L0/L1 functions such as Lane Departure Warning, Driver Drowsiness Detection, Advanced Emergency Braking System, Adaptive Cruise Control, Adjustible Speed Limiter Device, Blind Spot Detection. With the new regulation proposal, Driver Drowsiness
ICPC 2019 – 5.2
110
Detection & Blind Spot Detection functions will be regulatory as Lane Departure Warning & Advanced Emergency Braking was in 2015.
Ford F-Max is equipped with Adaptive Cruise Control function which has extended braking capability on top of regulatory functions – Lane Departure Warning & Advanced Emergency Braking. Thanks to connectivity technologies and tophographical maps, F-Max has a Predictive Cruise Control function so called MaxCruise which estimates the optimal speed profile using road tophography and drivers’ set speed, resulting in up to %4 fuel economy as an economy & comfort function.
Potential Future Functions on Trucks
On top of the above mentioned ADAS functions - with the upcoming automated driving developments - Highway Autonomy, Confined Area Autonomy and Connectivity Technologies hold a great business potential in trucking industry.
Although each three potential areas have their own business and operation models, combination of these technologies will lead to a new logistic model, so called hub-to-hub transportation. This new logistic model combines conventional trucks for the first and last mile delivery with automated L4 or even driverless (L5) trucks for the middle part on the highways. Trailer/Load changes will be performed in transfer hubs which has direct access and connection to highways. Confined Area Autonomy takes the stage in transfer hubs while parking, attaching-deattaching trailers and maneuvering, whereas Highway Autonomy enables autonomous driving and platooning on highways. To improve overall system efficiency and safety during hub-to-hub transportation model and other business models, connection to the infrastructure and other vehicles (V2x) is essential and indispensable.
HIGHWAY AUTONOMY
Global OEMs are all carrying out various activities in the aspect of “transportation-as-a-service”. It is critical for vehicle manufacturers to grasp the idea behind x-as-a-service and put strategic plans in place. Autonomous driving is certainly an enabler of large-scale hub-to-hub transportation, in a way creating virtual road trains, and potentially lowering the costs road transportation, while increasing the speed, safety and reliability. With Level 4 Highway Autonomy of trucks, following social benefits are expected:
• For the drivers, reduced stress levels and ability to carry out other tasks during the ride.
• Reduced level of traffic congestion; saving time for all road users.
• Safer highway; less number of accidents.
• Reduced fuel consumption and air pollution
• Less transportation costs for goods and services Long-haul trucking requires driving day and night through varying weather, road and geographical conditions in just one mission. Because of this reason, effective automation should include the capability to handle all of these different conditions. According to OEM’s public announcements, state-of-the-art commercial solutions for L4 will be available by 2020-2021 but will only be able to handle autonomous driving under certain conditions (low speed, day, good weather etc.). That’s why, one of the main focus areas at Ford Otosan is to enable automated long-haulage in adverse conditions. Technical approach towards this goal is mainly based on novel deep learning models that are trained with data collected by trucks under several different conditions in Turkey. Ford Otosan’s existing fleet and truck usage know-how help feed the AI researchers with good quality data. Together with platooning, predictive cruise control, and other fleet operation functionality, L4 autonomy will bring further reduction of transportation costs and pave the way towards L5 trucks.
Although the results achieved in the last decade enabled a breakthrough in the world of autonomous vehicles, there are still many scientific challenges that require extensive research. These challenges may be briefly summarized under the below headings:
• Intelligence level a. Model architecture b. Training methods c. Data quality
• Adaptability level: Capability of the model/system to adapt to different conditions (road, weather, geography etc.)
• Speed & Processing Resources Required: a. Training speed & performance b. Resource requirements for real-time
performance
• Safety: Capability of the system to overcome unsafe situations
• Security: Vulnerability of the system to cyber/physical attacks
• Ethics: Ethical issues regarding training & decision making processes
• Transparency: How to track the decisions made during the ride and how to inform the driver / passengers about them
Ford Otosan is working on creating a holistic Autonomous Driving SW design & evaluation strategy and finding optimal ways to combine the strengths of AI and non-AI based approaches. This requires very
ICPC 2019 – 5.2
111
well linked theoretical analyses, simulations and field testing.
Many of the above aspects need further improvement in order to be able to deliver an L4 Autonomous Long-Haul Truck. With all these unsolved problems, there is an opportunity for the truck OEMS and suppliers, and start-ups to create novelties that enable competitive advantage, in terms of cost, quality or timing. Research at Ford Otosan is mainly geared towards creating competitive advantage in the fields of perception and planning for long-haul trucks under bad weather, road, and environment conditions. Enabling no-stop long-haulage under adverse conditions will create commercial benefits for the stakeholders as it also brings safety benefits.
In addition to the technical developments which are mainly concentrated on unsolved problems of L4 Autonomous Long-Haul Truck, infrastructural requirements and customer experience/habits are also investigated. For these spesific purposes, more than 20 Ford F-Max tractors are observed in a specific route presented in Figure 1.
Figure 1 Istanbul-Ankara Highway
The highway connecting Istanbul to Ankara is selected as the specific route for the above-mentioned investigations since it is the longest and mostly used highway in Turkey according to the information provided in the official website of “Ministry of Transport and Infrastructure”[3]
Considering the regulations/rules being discussed for Platooning function, Istanbul-Ankara highway is divided into 25 segments (from exit-to-exit) to be able to perform an infrastructural analysis more efficiently. Segments have varying lengths from 8.5 km to 47.5 km with an average of 17.8 km and results in a total of 445 km highway. The segment lengths are provided in a bar chart in Figure 2.
Although, Autonomous Driving or specifically Platooning on shorter segments does not bring significant benefit on fuel consumption and driver comfort, all defined segments are inspected separately for infrastructural requirements. For each segment defined in Figure 2, Lane Detection Performances are investigated separately which is a
cumulative result of camera performance, lane marking status, road and weather conditions.
Figure 2 Istanbul-Ankara Highway Segment Lengths
Results obtained from 20 Ford F-Max tractors show that lanes can be detected for the %99,52 (average of all segments) of the complete highway which means during 2.13 km of the total 445 km, lanes are not detectable or camera is not able to detect lanes due to several reasons. Figure 3 and Figure 4 provides some examples for detected and missed lane marking sections of the highway, respectively.
Figure 3 Examples of Good Lane Marking Sect. on the Highway
In addition to the lane detection performances on different segments of the highway, driver workloads/habits are also investigated segment per segment to quantify the benefits of potential highway autonomy functions. Accelerator Pedal & Brake Pedal (or auxiliary brake activation) are frequently used by drivers while travelling on the highway and those two driving tasks hold a substantial portion in the driver’s
ICPC 2019 – 5.2
112
workload on top of steering and monitoring driving environment.
Figure 4 Examples of Missed Lane Marking Sections on the Highway
Figure 5 presents the ratio of accelerator pedal, brake pedal, auxiliary brake usage to total travel time while travelling on Istanbul-Ankara highway with ACC-On and ACC-Off conditions, respectively. This information provides an estimate potential of a L2-Automated Truck Platooning and L4-Highway Pilot Platooning on driver workload reduction.
Figure 5 Driver Workload Reduction by ACC on Istanbul-Ankara Highway
Even with Adaptive Cruise Control, driver workload generated by acceleration & braking tasks is reduced by half which strongly points out that the driver workload improvement will be more with L2-Automated Truck Platooning on top of its efficiency on fuel economy that the function will bring.
CONFINED ZONE AUTONOMY
Highway Autonomy mainly covers autonomous driving between transfer hubs on highways but Autonomous Driving in Confined Areas is complimentary for a complete hub-to-hub transportation, which is the future vision for road transportation & logistics. Considering that tractor-trailer combinations can park at the associated locations in the transfer-hubs autonomously or tractors can attach to the designated trailers autonomously within the transfer hub, the last piece of the hub-to-hub transportation puzzle will be completed.
On top of being complimentary to Highway Autonomy for a complete hub-to-hub transportation; Confined Zone Autonomy has its own potential business models especially in ports, logistics areas and construction/mining areas. Driverless, remotely supervised or even cabless trucks for some specific usages will be possible with Confined Zone Autonomy.
Ford Otosan is currently involved in 4 different EU-Funded projects which have different use-cases related with Confined Zone Autonomy; TrustVehicle [4] & PRYSTINE [5] are concentrated on Auto-Trailer Parking function at Logistic Areas, 5G-Mobix [6] & NewControl (will start in June-2019) are taking Remotely Supervised Trucks on Customs Area & Construction Area as use-cases, respectively.
Auto-Trailer Parking Function @ Logistic Areas
One of the most challenging driver tasks on tractor-trailer combinations is the reverse parking or so called backing to a docking station in a logistic area due to the articulation between tractor&trailer as presented in Figure 6.
Figure 6 Sketch of a Tractor-Trailer Combination Backing to a Dock
ICPC 2019 – 5.2
113
Ford Otosan is mainly concentrated on the identification of optimum path for the tractor and trailer during reverse parking and improvement of tracking performance in TrustVehicle project. The optimum path calculations are performed based on the robust & fail-safe environment perception algorithm, so called occupancy grid generated within PRYSTINE project. In addition to the environmental perception, dock detection algorithms are being developed in PRYSTINE project as well. Figure 7 presents the initial results of dock detection algorithm.
Figure 7 Initial Results of Dock Detection Algorithm
Remotely Supervised Trucks @ Customs & Construction Areas
Autonomous Driving of trucks hold a great potential on closed construction areas, mining areas and other confined areas such as customs. In a strictly confined, challenging and even a dirty environment, equipping the area with relevant sensors is more efficient, safer, cleaner and cheaper than equipping each and every truck. With this approach the trucks will be remotely supervised from a control center, which will also enable the optimization of co-operative task management for each truck or any other construction equipment. Figure 8 shows a detailed sketch of the remotely supervised trucks at a construction area.
Figure 8 Remotely Supervised Trucks at a Construction Area
CONNECTIVITY TECHNOLOGIES
Connected vehicles will have significant role for transportation, environment and road safety. Vehicles will communicate with other vehicles (V2V), infrastructure (V2I) and pedestrian, cyclists or anything (V2X). The connected ecosystem will enable safer roads by avoiding potential crashes, reduced congestion by efficient route and speed optimizations, lower CO2 emissions by less fuel consumption.
It will be possible to see the beyond the obvious by interacting with the other vehicles, infrastructure such as traffic lights, road side units (RSU) or road users. Instead of limiting the driving capabilities by the on board sensors like radar or camera it will be possible to get wide range of valuable information from the V2X units within the vehicle.
The data could be exchanged between vehicle to everything and the collected and consolidated data would be sent back to vehicle to have better environment understanding. The increasing number of connected vehicles will improve the data accuracy and freshness.
Vehicles could get benefit from that real-time connectivity data in various ways. While that information is used to prevent dangerous situations such as traffic accidents any information related to weather, road conditions or traffic lights would also be used for route or autonomous driving profile optimization.
Truck platooning is one of the use cases which are enabled by V2V technology. It is a string of vehicle which is moving cooperatively by sharing the vehicle local information and platoon specific messages through the V2V communication. V2V enables a reduced time gap between the trucks. As a consequence of reduced time gap, fuel efficiency increases and CO2 emission reduces.
Ford Otosan and AVL have started a 3-year joint R&D project to develop “Platooning” technology for long-haul trucks. Within that project, for which field tests are ongoing, DSRC based communication is being used as the V2V technology.
In addition to that, Ford Otosan has an active role in 5G Mobix – H2020 project for cross border platooning, platooning see-what-I-see functionality and real time remotely supervised truck routing at a customs site, which will be enabled by 5G based C-V2X technology. Despite the numerous advantages of platooning, from the point of view of the vehicles that are at the back, following the lead vehicle in a platoon can cause lack of attention and anxiety while driving, since trailers are wide and high enough to
ICPC 2019 – 5.2
114
cover driver sight. To circumvent them, a “see-what-I-see” application will be designed and implemented for truck platooning within the 5G Mobix project, which will be providing the road view of the leader truck to the others in the platoon.
As another use case of the 5G Mobix project, real time remote truck routing will be demonstrated at a customs site. One of the key ideas behind remote supervised truck control in this project is controlling the non-autonomous drive-by-wire trucks by the use of external sensors in the field (i.e. customs site, logistics hub etc), instead of the perception sensors on the truck. In this way, the truck will be able to move from one point to another without the driver, performing tough maneuvers autonomously in a small area, which has other vehicles and pedestrian traffic. Sensor fusion in this case will include data from both the truck and the field. This will enable the driver to save time to expedite other procedures required to get border pass approval while, at the same time, traffic efficiency will be increased, and the average vehicle border crossing time as well as the number of traffic accidents due to human error will be decreased at customs sites.
CONCLUSION
All in all, Automated Driving on Highways and Confined Areas, on top of ADAS and Connectivity Technologies will shape the near future of transportation, logistics and trucking ecosystem. Ford Otosan is developing not only ADAS functions to increase traffic safety and driver comfort with the current technologies but also Automated Driving technologies boh on Highways and Confined Areas to be able to provide an end-to-end solution for potential customers, especially for hub-to-hub transportation and remotely supervised trucks in confined areas.
REFERENCES
[1] https://ec.europa.eu/eurostat/statistics-explained/index.php/Freight_transport_statistics_-_modal_split#Modal_split_in_the_EU
[2] ERTRAC-CAD Roadmap-2019
[3] http://www.uab.gov.tr/eng/
[4] http://www.trustvehicle.eu/
[5] https://prystine.eu/
[6] https://www.5g-mobix.com/
DEFINITIONS, ACRONYMS, ABBREVIATIONS
CAD Connected Automated Driving.
115
ICPC 2019 – 5.3
Digital Twins – Enabler for Digitalization
Thomas Fischinger, Stefan Hirschenberger, Franz Rimböck
Wacker Neuson Beteiligungs GmbH
Copyright © 2019 AVL List GmbH, Wacker Neuson Beteiligungs Gmbh and SAE International
ABSTRACT
At the moment we stand on the edge of a technical revolution that will fundamentally change the way we live, work and communicate. The transformation into a digital society is taking place at an unprecedented speed. For machinery industry this means to increase the flexibility and adaptability of industrial production systems by implementing virtual product- and
production models, which are referred to as digital twins. The goal is to convert the physical and virtual world starting from optimized product development, processes for new machines to a predictive spare part delivery for our customers (see Figure 1). At Wacker Neuson we tackle these new challenges that rise with the digital transformation by subdividing them in three major streams referred as Smart Processes, Smart Factory and Smart Customer Solutions
Figure 1 Concept of a digital twin as aimed at Wacker Neuson Group
INTRODUCTION
The evolution of the digital twin in industrial environment has started with the possibilities
computer-aided design (CAD) in the early 70s 1971 by Patrick J. Hanratty [1]. This has revolutionized and disrupted the product development as well as the production processes. Another corner stone in the evolution has been the concept of product lifecycle proposed by Dean [2] in 1950. This concept was extended to the engineering field by the influence of concurrent engineering [3]. Therefore the product
lifecycle covers the entire process from product planning, product developing, manufacturing processes as well as sales and after-sales service [4].
Along with the developments and applications of new information technologies, a new era of smart manufacturing is coming. By converging the physical world and the virtual world, a series of smart operation in the manufacturing process becomes possible. This concept is known as digital twin [5-7]. In this paper the
ICPC 2019 – 5.3
116
author describes the concept of a digital twin on example of Wacker Neuson Group.
DIGITAL TWIN AT WACKER NEUSON GROUP
The Wacker Neuson Group develops, produces and distributes concrete technology, compaction equipment, worksite technology and compact construction equipment, also offering a range of complementary services. Next to the headquarter in Munich, the Wacker Neuson Group have seven production and development sites around the world employing around 5,500 people.
Motivation
A suitable digital twin strategy enables a company as Wacker Neuson Group to accelerate and de-risk new product introduction, supports a more flexible and optimized production process and allows the implementation of new data-driven services and business opportunities. Unfortunately, a suitable software suite is often not available. At Wacker Neuson Group we follow a strict concept of standardization and centralization. The key is to establish scalable business processes, that match SAP standards to the highest possible degree. Therefore, we are working with SAP Visual Enterprise (SAP VE) as a backbone for the digital twin in production and add functionality with the help of self-designed Fiori-apps. This enables us to adapt in accordance to the specific needs of our historically grown production sites.
Digital twin-driven processes
DIGITAL TWIN-DRIVEN, VIRTUAL PRODUCT DESIGN
Traditional product design requires professional knowledge and expertise of each part of the process. In recent years, the processes in product development have become more virtualized. Starting in the conceptional design phase, the designer define the concept of the new product. The input of the digital twin and data regarding customer satisfaction, product usage, product sales as well as other information supports the designer. During the detailed
design phase the virtual product prototype is created including product functions and possible product configuration. Essential hereby is an additive-stacked variants configuration. In this phase, our virtual product design run through several simulation processes e.g. kinematic simulation to optimize our construction equipment. The necessary data is obtained by simulation algorithms fed with real-life machine data and defined boundary conditions. The virtual verification of the design substitutes the physical prototype to a large extent. This enables accelerated and cost-efficient product development.
DIGITAL TWIN-DRIVEN, VIRTUAL PRODUCTION
In the next step information coming from product engineering needs to be translated for manufacturing purposes. At Wacker Neuson Group, we use SAP VE to bridge the gap between engendering and manufacturing by referencing to the same data provided by SAP ERP system (see Figure 2). This enables our team to virtually plan the production in accordance to the resource allocation such as materials, equipment tools, method time measurements data etc. within the assembly line. After this step purchasing respectly make-or-buy decisions are initiated. Optimization process between resource allocation purchasing and logistics is key-performance-indicator based.
DIGITAL TWIN-DRIVEN PRODUCTION AND ASSEMBLY
The production and assembly process starts with a model sequence planning developed in-house to fit the requirements needed (see Figure 2). This tool automatically generates an optimizes an assembly sequence in accordance to historical data, assembly rules and customer orders. The algorithm is realized within a SAP Fiori app to ensure a smooth interface to our SAP ERP system and a maximum of flexibility. After starting a new machine within an assembly line, this machine is been tracked by a geo-tracking system based on ultra wide band technology. So the progress of the assembly is documented at anytime and linked to our quality control systems, which is also based on pure SAP standard functionality (see Figure 2).
ICPC 2019 – 5.3
117
Figure 2 Extract from the systems involved
To provide employees with a shop floor suitable frontend we count on custom developed Fiori Apps once more. Wacker Neuson Group use variant specific checklists to ensure product quality within the manufacturing line. Serial numbers of function critical parts get recorded and possible problems within the assembly line are documented . The data which is gathered throughout the whole assembly line enriches the digital twins of the single product instances with product lifecycle management (PLM) relevant information. Due to the progress tracking in the line, the pre-assembly can be triggered precisely. Due to the real-time changes in the assambly line, the system need an iterative adjustment and optimization.
The possibility of incorrect assembly is prevented by an automatic plausibility check, which uses data from SAP ERP. Another part of the digital twin in production is the worker-guidance system (WGS), which provide the assambly worker with necessary information. Next to general information regarding the machine, the worker gets specific data about options, safety instructions, quality instructions as well as engineering change notices. Due to the possibility of providing feedback to these topics within the WGS, the digital data-set regarding the product or production design is enriched.
DIGITAL TWIN-DRIVEN FIELD USAGE AND SERVICES
In order to be able to establish itself permanently on the market in a rapidly changing market and in times of globalization, it is important to know in detail its market, its customer segments, as well as the customers themselves and their requirements. In our developments, we rely on the involvement of our customers at an early stage to get a voice of the customer. The different systems and possibilities of digitization and the internet of things enable us to develop our products and services even more efficiently and in a more target way.
At the heart of this process are the integrated telematics modules and the corresponding app landscape. The development of a solution for a cross-product fleet management system for light and compact construction equipment is attributed to the end product. For Wacker Neuson Group it is important to offer a total solution for all equipment involved in the construction process. Next to the medium and large equipment that can be connected to the CAN-BUS system, the light construction equipment has its own challenges. For example, a gasoline-powered rammer has no power supply of its own. There are also special requirements due to the high vibration. In these applications, a possible technical solutions can be realized via a bluetooth low
ICPC 2019 – 5.3
118
energy beacons in conjunction with a corresponding app on mobile devices.
Using different techniques, the all machines automatically login on their own in case of maintenance, low levels, malfunctions, unexpected relocation, etc. – in real-time on mobile phones or desktop PCs. This enables our customer to minimize machine downtime, optimize repairs and maximize the return on the machine.
The backend of our fleet management and service management oriented products is the Wacker Neuson Cloud. Within this system, the data are collected and processed for the customer. In addition, Wacker Neuson Group is able to offer new business services such as pay per use, solution as a service, etc.. The machine data prove a good insight into how the machines are used in field and how Wacker Neuson can improve the product development to fit these requirements (see Figure 1). Next to the improvement of our products, the data reveal information about future behavior.
CONCLUSION
With the opportunities offered by a world of ever faster technologies, systems and processes must also be adapted at the same pace. Therefore, the digital twin of a process will always be a virtual picture corresponding to the options available. In this paper the author explained the current state of the attemps to digitalize our PLM data within a consistant system landscape at the Wacker Neuson Group. In the next steps the data will be used for smart business services and analytical services (see Figure 3).
Figure 3 Overview of the main system components of the digital twin at Wacker Neuson Group
REFERENCES
[1] Hanratty, P. J. (2005) MSC: Company History. Retrieved from https://web.archive.org/web/20050209155207/http://mcsaz.com/about/founder.htm
[2] Dean J (1950) Pricing policies for new products. Harv Bus Rev 28(6):45–53
[3] Nevins JL, Whitney DE (1989) Concurrent design of products and processes: a strategy for the next generation in manufacturing. McGraw-Hill Companies, New York
[4] Ryan C, Riggs WE (1996) Redefining the product life cycle: the five-element product wave. Business Horizons 39(5):33–40
[5] Glaessgen E, Stargel D (2012) The digital twin paradigm for future NASA and US Air Force vehicles. 53rd AIAA/ASME/ASCE/ AHS/ASC Structures, Structural Dynamics and Materials Conference 20th AIAA/ASME/AHS Adaptive Structures Conference 14th AIAA 1818
[6] Tao, F., Cheng, J., Qi, Q. et al. (2018) Digital twin-driven product design, manufacturing and service with big data. Int J Adv Manuf Technol 94: 3563.
[7] Q. Qi and F. Tao (2018) Digital Twin and Big Data Towards Smart Manufacturing and Industry 4.0: 360 Degree Comparison. IEEE Access, vol. 6, pp. 3585-3593
DEFINITIONS, ACRONYMS, ABBREVIATIONS
CAD Computer-aided design
SAP VE SAP Visual Enterprise
WGS Worker Guidance System
PLM Product lifecycle management
119
ICPC 2019 – 6.1
Powertrain Trends and Developments in the Commercial Vehicle Industry
Dr. Carl Hergart
PACCAR Technical Center
Copyright © 2019 AVL List GmbH, Paccar Inc. and SAE International
ABSTRACT
The last several decades have seen dramatic improvements in the performance, fuel efficiency and environmental footprint of powertrains for commercial applications. Today’s diesel engines are more power dense, efficient and clean than they have ever been. Yet, the challenges for the future are significant. With increasingly stringent requirements up to and including zero emission operation, powertrain development continues unabated.
Substantial advances in the efficiency of engines, transmissions and axles notwithstanding, perhaps the most notable powertrain development over the last 10 years has been the seamless integration of all components. This paper will review past, current and future developments aimed at evolving not only conventional diesel powertrains, but also those incorporating increasing levels of electrification.
INTRODUCTION
The importance of commercial trucking cannot be overstated. Over 10 billion tons of freight is transported on trucks every year in the United States, representing 70% of domestic tonnage. 7.7 million people were employed in jobs relating to trucking activity in 2017 in the U.S. [1]. Applications span a spectrum of vocations and it is important to understand the different use cases. Similar to the automotive sector, the commercial industry is very much in the spotlight with regards to emissions reductions. Regulatory and competitive pressures have driven trucks to become increasingly clean and efficient. Improvements to the individual powertrain components and subsystems have been substantial, but perhaps the most remarkable developments have
1 C8 SC HR = Class 8, Sleeper Cab, High-Roof; C7 DC MR = Class 7, Day Cab, Mid-Roof
occurred in the area of system integration. Today’s powertrains are the result of a sophisticated interplay between the major components: engine, aftertreatment, transmission and axles. Advanced control algorithms run as a thread through the operation and actuation of the subsystems. Powertrain components are carefully selected with the overall mission of the truck in mind. Continued pressure to improve transport efficiency and reduce the environmental impact of commercial powertrains will drive future developments. The upcoming North American Greenhouse Gas Phase 2 regulations call for reductions of up to 27% (Figure 1), much of which will come from improvements to the powertrain. The subsequent sections of this paper will discuss some of the key technology improvements and future opportunities for the major powertrain components and subsystems.
Figure 1 North American Greenhouse Gas Phase 2 regulations for two tractor configurations1
ICPC 2019 – 6.1
120
ENGINE TECHNOLOGIES
The most direct way of improving the efficiency of diesel engines is to increase the mechanical yield from the chemical energy stored in the fuel. Hence, there is active research ongoing to optimize the combustion system. The design of today’s combustion chambers is the result of a century worth of practical experience enhanced by sophisticated high-fidelity simulations, optimizing such parameters as piston bowl shape, injector geometry and port geometry. Improvements in material properties have enabled increases in peak cylinder pressure and turbocharger speeds, ultimately increasing efficiency while complying with ever more stringent emissions standards. Figure 2 shows the evolution of engine tailpipe Nitrogen Oxides (NOx) and Particulate Matter (PM) standards for Heavy-Duty commercial vehicles in North America over the past 35 years, along with some of the key enabling technologies. From 1985 until 2002 Heavy-Duty onroad emissions standards in North America were largely achieved by optimizing and calibrating in-cylinder performance parameters. In 2002-2004 Exhaust Gas Recirculation (EGR) was introduced and 2007 saw the introduction of exhaust gas aftertreatment systems.
Figure 2 Evolution of Heavy-Duty onroad NOx and PM emissions in North America (source: DieselNet)
At the same time efficiency has improved. Figure 3 shows how the peak Brake Thermal Efficiency (BTE) of diesel engines in commercial trucks has evolved since 1960. We note that efficiency has continued to increase while engines have become much cleaner. The dip in efficiency around 2002 is attributed to the introduction of EGR, which required increasing the
2 It is interesting to note that the ratio of DEF to Fuel is
approximately 65% in the U.S. vs. 30% in Europe, making it more attractive to pursue higher engine-out NOx in Europe than in the US from a total fluid consumption perspective.
engine back pressure. Included in the figure is also the 55% SuperTruck II target established by the U.S. Department of Energy.
As BTE inches up towards the Carnot theoretical limit, researchers also turn to ways in which to harness the energy contained in the exhaust. Such Waste Heat Recovery (WHR) methods include turbo-compounding and the Organic Rankine Cycle (ORC).
Figure 3 Progression of peak engine Brake Thermal Efficiency in HD trucks over the last 60 years
As part of the SuperTruck II program, PACCAR is exploring technologies such as the Miller cycle, low friction materials, thermal barrier coatings and ORC to achieve an unprecedented 55% BTE [2].
Modern diesel engines are equipped with an aftertreatment system, consisting of a Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF), Selective Catalytic Reduction (SCR) catalyst and an Ammonia Slip Catalyst (ASC). The system has to be designed in such a way as to optimize the overall system efficiency while meeting prevailing emissions standards. Figure 4 shows the familiar trade-off between BTE and engine-out NOx (solid lines). The dotted set of lines take the total fluid consumption into account, illustrating that an optimum can be found for engine-out NOx. Interestingly, this optimum occurs at different engine-out NOx-levels depending on the cost of Diesel Exhaust Fluid (DEF)2. The trade-off in Figure 4 also illustrates the challenge of continuing to improve engine efficiency in the face of regulatory reductions in NOx
3, potentially requiring reduced engine-out NOx.
3 Per a recent staff white paper, the Low NOx regulation is likely to
be set in the range of 0.05-0.08 g/bhp-hr. CARB is also proposing to implement a new Low Load Cycle over which compliance has to be demonstrated.
ICPC 2019 – 6.1
121
Figure 4 Fuel/Fluid Consumption vs. Engine-Out NOx
Downspeeding has long been discussed as a means to improving efficiency. For transmissions and axles there is a pretty straightforward relationship between efficiency and downspeeding, whereas it is a bit more complicated for the engine. In a downsped engine, the combustion takes place within a shorter crank angle window, which gets the overall process closer the ideal thermodynamic constant volume cycle. The turbocharger also tends to operate more efficiently at reduced speeds. On the other hand, in order to maintain power output, a downsped engine has to develop higher torque, which is typically accompanied by increased cylinder pressures and thermal loads. The core engine design and overall powertrain configuration become very important in the ability to take advantage of downspeeding.
Future technology improvements, such as advanced combustion concepts and low friction materials will potentially change the engine speed at which peak efficiency is achieved.
TRANSMISSION TECHNOLOGIES
The basic role of the transmission is to transfer power from the engine to the drivetrain, such that overall powertrain efficiency is maximized. There are some key factors to consider when it comes to selecting the right transmission for a given application:
• Overall gear ratio
• Transmission type
• Direct Drive vs. Over Drive
The overall gear ratio should be chosen to achieve high efficiency at cruise conditions, while ensuring adequate startability and gradeability. Furthermore, the steps between the gears may be progressive in order to keep variations in engine speed to a minimum, especially in the upper gears.
Historically, the North American market has been dominated by manual transmissions. However, as
controls and actuation have become more sophisticated and driver demographics are changing, recent years have seen a noticeable increase in the use of Automated Manual Transmissions (AMTs). Unlike automatic transmissions, AMTs do not have a torque converter, which make them the preferred choice for efficiency conscious line-haul customers. Automatics are finding more widespread use in vocational applications, where the powershift capability is an important attribute. Automated shifting requires seamless integration between engine, clutch, and transmission. Shift strategies are developed allowing the engine to operate in its most efficient region, while having sufficient power to climb hills without resorting to excessive shifting or gear hunting. Features such as launch and low-speed maneuverability require a delicate interaction between engine, clutch and transmission. The recently introduced PACCAR Transmission (Figure 5) is representative of a new class of Automated Transmissions, which - unlike traditional AMTs – were never intended to be manual and as such are not constrained by a shift pattern conducive to manual operation. This creates additional degrees of freedom, allowing a lightweight, compact and highly efficient design.
Figure 5 PACCAR 12-speed Automated Transmission
Relative to the question of whether to spec a Direct Drive (DD) or an Over Drive (OD) transmission, the former has historically been the preferred choice for Over-The-Road (OTR) applications primarily exposed to lower speeds (≤ 62 mph), moderate loads (< 80,000 GCVW) and flat terrain. Under these conditions, having a top gear direct connection between the engine and the transmission output shaft results in an efficiency advantage. However, with recent advances in gear design and architectures involving fewer meshes, the efficiency spread between DD and OD has narrowed. As a result, the
ICPC 2019 – 6.1
122
market in North America is increasingly migrating towards OD transmissions.
AXLE TECHNOLOGIES
As with the transmission, the choice of axle is highly application dependent. Some key design choices include:
• Axle configuration
• Axle ratios Figure 6 shows a schematic of two different axle configurations: a 6x2 and a 6x4. In North America, 6x4 dominates OTR applications. A 6x2 configuration has the advantage of lower rolling resistance, but has less traction than the 6x4 and may lead to accelerated tire wear. New technologies are emerging that allow either 6x2 or 6x4 operation depending on the condition. The Dual Range Disconnect™ concept offered by Dana [3] allows the tandem axle to operate as a 6x4 at startup, during backup maneuvering or in other environments where traction is cruicial. As the truck nears a predetermined speed or condition, the inter-axle shaft disconnects from the power divider in the forward axle as well as the ring gear in the rear axle, allowing the axle to operate in a more efficient 6x2 mode. At the same time, it shifts the forward axle to a faster ratio that enables engine downspeeding. The Meritor detachable and liftable rear tandem axle concept [4] is another concept allowing interchangeable 6x2 / 6x4 operation.
Figure 6 Examples of truck axle configurations
Engine downspeeding is typically accompanied by taller (lower numeric ratio) rear axles, which helps improve efficiency. However, it is important to also consider the impact a taller ratio rear axle has on vehicle performance, NVH, driveline weight and torque management.
The recently introduced PACCAR 40,000 lbs. tandem drive axle, shown in Figure 7, offers gear ratios from 2.47 to 3.70 and supports both direct and overdrive drivetrains.
It features a patented through-shaft pinion design in order to eliminate gears in the forward drive axle and reduces oil churning losses with a unique passive lubrication system and the use of laser welded joints instead of bolts.
Figure 7 PACCAR 40k tandem axle
POWERTRAIN INTEGRATION
While the individual subsystems have become increasingly efficient, it is the seamless integration of all building blocks that have enabled major strides in efficiency, performance, drivability and uptime – attributes essential to customers. For line-haul applications, transmission and axles are typically selected such that the engine operates in its most efficient point at cruise conditions. Figure 8 shows iso-contours of engine efficiency as a function of speed and power. The figure also illustrates where the engine operates while the truck is cruising at 65 miles per hour in the 11th and 12th gear, respectively. We note that the gear selection has a significant impact on engine efficiency.
The overall powertrain efficiency is described by the following expression:
𝜂𝑃𝑡𝑟𝑎𝑖𝑛 = 𝜂𝐸𝑛𝑔𝑖𝑛𝑒 ∙ 𝜂𝑇𝑟𝑎𝑛𝑠 ∙ 𝜂𝐴𝑥𝑙𝑒 (1)
where 𝜂𝑃𝑇𝑟𝑎𝑖𝑛 is the overall powertrain efficiency, 𝜂𝐸𝑛𝑔𝑖𝑛𝑒 represents the engine efficiency, 𝜂𝑇𝑟𝑎𝑛𝑠 is the
transmission efficiency and 𝜂𝐴𝑥𝑙𝑒 is the axle efficiency.
Both transmission and axle efficiency generally improve with downspeeding, whereas there is an optimum for the engine as seen from Figure 8 and discussed in the prior section on engine technologies.
ICPC 2019 – 6.1
123
Figure 8 Engine efficiency vs. speed and region of operation at 65 mph cruise condition
The choice of engine rating is critical in achieving the overall desired powertrain performance and fuel economy. This is illustrated in the following by contrasting the performance of two different engine ratings. Figure 9 shows the power available in the two top gears (11th and 12th) for a given application along with road loads corresponding to 0% (flat), 1%, 2%, and 3% grade. The 12th gear represents an Over Drive, enabling engine downspeeding. We imagine a scenario in which the truck is cruising at 65 mph in 12th gear as it approaches a 2% grade. Power will be increased until it reaches point A in the figure, at which point no more power is available in the 12th gear. Since insufficient power is available for the given grade, vehicle speed will start to decrease (transition from point A to B). When the vehicle speed hits the lower threshold of the cruise control speed window (assumed here to be 61 mph), a downshift to 11th gear is executed (B -> C). In 11th gear sufficient power is available to accelerate the vehicle back to the 65 mph set speed (C -> D), at which point the transmission performs an upshift in order to take advantage of the efficiency benefits of engine downspeeding (see Figure 8). The cycle is then repeated. The result is fluctuating vehicle speed and excessive shifting, which has a detrimental impact on fuel economy4.
4 The fuel consumed by accelerating the engine speed during a downshift is never recovered.
Figure 9 Suboptimal engine-transmission interaction
In contrast, we consider an engine calibrated to provide constant power across the gears, as illustrated in Figure 10. Similar to the case discussed above, the vehicle speed will decrease from the 65 mph set speed down to 61 mph as the 2% grade is encountered. However, unlike the situation described in Figure 9, no downshift will occur since there is no more power available in 11th gear and the speed will remain at 61 mph with the transmission in 12th gear. The result is a slower ascent up the hill, but with less shifting and better fuel economy. Moreover, the reduced vehicle speed turns out to be advantageous upon cresting the hill since it reduces the need for engine braking and subsequent downhill speed control. The net effect is typically a fairly minor impact on overall trip time but a noticeable positive impact on fuel economy.
Figure 10 Constant power engine rating
Predictive Functionality
Vehicle connectivity has emerged as an important enabler to transport efficiency. Today’s trucks have
ICPC 2019 – 6.1
124
access to GPS-based terrain information that makes it possible to control and optimize powertrain performance. Examples of these so-called Advanced Predictive Features are:
• Predictive Cruise Control
• Predictive Shifting
• Neutral Coast
Figure 11 illustrates how these features operate in a scenario where a truck is moving through a rolling hill terrain. Predictive Cruise Control (PCC) maintains a vehicle speed set by the driver, but allows variation within a certain range to ensure optimal efficiency and drivability. As the truck approaches a hill, the transmission executes a predictive downshift to ensure sufficient torque is available to ascend the grade. As the terrain plateaus, the transmission avoids a temporary upshift based on information that the vehicle is about to encounter another grade. As the truck climbs the hill, the PCC set speed is allowed to droop knowing that speed will recover on the downhill. Such a strategy results in less frequent shifts and improves fuel economy without penalizing overall trip time. Upon cresting the hill a feature referred to as Neutral Coast is activated, which causes the transmission to shift into neutral with the engine idling. Future extensions of this strategy may involve turning the engine off during the downhill coast event. This will obviously require uninterrupted power supply to critical accessories, such as power steering.
Figure 11 Advanced Predictive Features
FUTURE TECHNOLOGIES
Key drivers to future technology development continue to be Total Cost of Ownership (TCO), performance and productivity, while meeting increasingly stringent regulatory requirements. The latter include the Greenhouse Gas Phase 2, the Low NOx regulation proposed by the California Air Resources Board (CARB), emerging zero emission standards and urban area diesel bans. Technology advancements will benefit from progress made in the areas of automation, connectivity and electrification.
Automation and Connectivity
Our society is more connected than ever and through our smartphones and tablets there is a wealth of information at our fingertips. As it relates to commercial trucks, there is a tremendous amount of data being generated and transmitted between vehicles and infrastructure elements. This data can include vehicle operating parameters, weather, traffic information and logistical information communicated by fleet operators and dealerships. The availability of all this data offers a range of opportunities for new products and services aimed at increasing uptime, productivity and customer satisfaction. The prior discussion on predictive functionality is an example of how vehicle connectivity can be leveraged to improve efficiency, but it is fair to say that the full potential of vehicle connectivity has yet to be realized.
Additional opportunities related to connectivity include smart routing that takes parameters such as weather and congestion into account in chartering the most efficient route for a truck. There is also significant progress made in the area of vehicle self-diagnostics, recognizing when failures are about to occur and communicating to the nearest dealership what parts may be needed. Such predictive maintenance will be key to maximizing truck uptime.
Connectivity is also a critical enabler to automation, which is a topic receiving plenty of attention currently. As disruptive as many of the autonomous developments may seem, it is worth noting that automation really represents the continuation of a long-term trend. Many of the systems we today take for granted on vehicles, e.g. Anti-Lock Braking System (ABS), Electronic Stability Control (ESP), Automated Manual Transmissions (AMTs), manage tasks that originally fell on the driver to execute. A truck driving itself is obviously a significant extrapolation of that paradigm.
Advanced Driver Assistance Systems (ADAS) are aimed at improving safety, productivity and comfort of the driver. The SAE standard J3016 defines 5 ADAS levels, ranging from longitudinal or lateral control (e.g. Adaptive Cruise Control, Lane Keeping Assist) to fully autonomous operation. The latter requires a large amount of additional sensors on the truck (cameras, radars, LIDAR) and it is important to consider the impact on TCO in deploying higher levels of automation.
Truck platooning is an ADAS technology that has the potential of improving fuel economy by allowing trucks to draft. Platooning can be an ADAS level 1 or 2 depending on whether the following truck(s) feature either or both longitudinal and lateral control. Trucks
ICPC 2019 – 6.1
125
in a platoon typically communicate through a 5.9 GHz Dedicated Short Range Communication (DSRC) protocol. Not having a driver in the loop puts high demands on the level of integration of throttle, brakes and steering system. There are also serious requirements regarding functional safety and system redundancy.
Electrification and Hybridization
Several factors will drive increased adoption of hybrid and electrification technologies in the commercial segment:
• A growing number of cities and municipalities are in the process of implementing zero emission zones [5],[6]
• Batteries have become more powerful, reliable and less expensive
• The automotive segment has started to embrace electrification in a serious way
Each application - whether it be Pick-up & Delivery, refuse, regional-haul or long-haul - has a a different set of requirements and an electrification concept that works for one application does not necessarily translate to another. A key industry priority is to look for synergies, commonality and modularity in order to accomplish efficient product development and attractive volumes of scale.
There are different degrees of electrification, ranging from all-electric powertrains to hybrids that rely on a separate powerplant5 for propulsion. Recognizing the breadth of the topic, the current section will be limited to a discussion on all-electric applications and a mild hybrid featuring accessory electrification.
Absent regulation requiring zero emission operation, there is no strong business case for an all-electric Class 8 long-haul truck. Given today’s battery technology, the electric equivalent of a line-haul truck carrying two 80-gallon tanks of diesel would have to carry approximately 25,000 kg of batteries6, far offsetting the weight benefit of removing the engine, aftertreatment and transmission. At roughly $200/kWh for typical state-of-the-art Li-ion technology, this would result in a cost upwards of $500,000 just in batteries. For Medium-Duty applications with their more limited range and power requirements, there is a more attractive and nearer term business case. Incidentally, these are also the type of applications that are likely to be most exposed to zero emission regulation introduced in urban areas.
5 In most cases this power plant is an Internal Combustion Engine, although recently fuel cells are receiving renewed attention.
The key components of an all-electric powertrain are: battery pack, electric motor, inverter and potentially a transmission depending on the application. The battery pack has to be sized to provide the desired range and have proper controls and thermal management to achieve adequate cycle life.
The voltage level is primarily dictated by the amount of power required, since the maximum current is effectively limited by the cost and weight of connectors and wires as well as the ability to route the cables. Higher current levels are also associated with winding losses.
A key architecture decision relative to all-electric powertrains is where to place the electric motor. There are broadly speaking two possibilities: Central Drive and e-axle. The two are illustrated in Figure 12. There are pros and cons associated with each. An integrated e-axle benefits from a direct connection between motor, transmission and wheel ends, not requiring a bevel gear to connect a driveline to the rear axle. As such, e-Axle are a little bit more efficient than the central drive topology. However, challenges include unsprung masses, vibration, hose- and wire flexing and packaging (especially when a gearbox is necessary). E-axles are also not compatible with the driveline and axle offerings today.
Figure 12 Electric Powertrain Topologies
Another key design decision is whether or not to connect a transmission to the electric motor. While less speed sensitive than diesel engines, the efficiency of electric motors does vary with speed and there are limits to their operation. The e-motor ratio defines the ratio between maximum and nominal motor speed. Depending on this ratio and the application requirements, a 1-4 speed transmission may be necessary. The most common motor types are Permanent Magnet Synchronous Machines
6 Assumes 8 MPG for a diesel powered truck, 2 kWh/mile and a battery weight of 10 kg/kWh.
ICPC 2019 – 6.1
126
(PMSM), Induction Magnet (IM), Synchro Reluctance (SynRel), and External Excited Synchro Machine (EESM). Of these the PMSM and the EESM typically offer the highest efficiency and power density, wheras the other types are more attractive in terms of cost.
A 48V mild hybrid offers an interesting intermediate step between the conventional powertrains of today and tomorrow’s all-electric ones. A key attribute of the 48V mild hybrid is the ability to power accessories, such as power steering, AC compressor and water pump independent from the engine. Such “smart” operation of accessories can yield notable efficiency benefits. It is also possible to replace the 12V starter with a more robust 48V system. Similar to the all-electric topology, a key design decision for the mild hybrid is the position of the electric motor. A Belt integrated Starter Generator (BiSG) is a common and cost effective mild hybrid topology owing to its relatively minor impact on the existing vehicle architecture. However, this architecture does not support coasting. Figure 13 shows an alternative approach where a 48V electric motor is connected to a transmission mounted Power Take-Off (PTO) unit. The PTO unit is also connected to the AC compressor, thus eliminating the one on the belt. This architecture supports removal of the engine Front End Accessory Drive (FEAD), which frees up space under the hood and enables optimization of the aerodynamic performance.
Figure 13 48V mild hybrid with accessory electrification
During normal cruise operation, the engine is connected to the transmission, which provides mechanical energy to the drivetrain and drives the accessories through the PTO unit. At the same time the batteries are being charged.
When the truck is coasting down a hill, the engine can be turned off while power is still provided to all accessories. At the same time, the batteries can be charged with excess energy available through regenerative braking.
An onboard 48V electrical system also opens up other interesting possibilities. The Low NOx regulation proposed by CARB for 2023-24 will likely require some kind of thermal management of the exhaust gas. This is something that could be accomplished by incorporating a 48V electrical heater.
CONCLUSION
Commercial trucking is at the heart of the transportation sector and a cruicial contributor to the growth of the global economy. Decades of continuous improvement in engine, transmission and overall powertrain technology have made trucks operating on the roads today cleaner and more efficient than ever before. Powertrain integration has been a key enabler to this by focusing on overall system optimization as opposed to attempting to maximize the performance of individual subsystems.
Connectivity has emerged as an enabler to improving truck efficiency and uptime through predictive functionality and diagnostics. Continued automation, up to and including autonomous operation, is already having a significant impact on the trucking industry and this trend is likely to continue.
Future regulatory and competitive pressures will require solutions for zero emission operation in urban and non-attainment areas, which is spurring development efforts in the realm of electrification. A key challenge for the OEMs is to identify a modular and scalable architecture that can cover all relevant applications. Battery technology development is progressing rapidly, but there is still not a compelling business case for Heavy-Duty all-electric long-haul trucks in the absence of incentives or zero emission mandates. Medium Duty battery electric applications appear more feasible in the near term and a 48V mild hybrid offers an attractive stepping stone between today’s conventional powertrain and future all-electric configurations.
REFERENCES
“American Trucking Trends 2018”, American Trucking Association, 2018
DOE Vehicle Technologies Office Annual Progress Report 2018
Dana e-Newsletter, Issue 3, 2015
Meritor product information, 2018
“The Zero Emission Vehicle (ZEV) Regulation”, CARB Fact Sheet, August 2018
“City bans are spreading in Europe”, Briefing by Transport & Environment, October 2018
ICPC 2019 – 6.1
127
DEFINITIONS, ACRONYMS, ABBREVIATIONS
ABS Anti-Lock Braking
ADAS Advanced Driver Assistance Systems
AMT Automated Manual Transmission
ASC Ammonia Slip Catalyst
BiSG Belt integrated Starter Generator
BTE Brake Thermal Efficiency
CARB California Air Resources Board
DEF Diesel Exhaust Fluid
DD Direct Drive
DOC Diesel Oxidation Catalyst
DPF Diesel Particulate Filter
DSRC Dedicated Short Range Communication
EGR Exhaust Gas Recirculation
ESC Electronic Stability Control
NOx Nitrogen Oxides
NVH Noise, Vibration and Harshness
OBD On-Board Diagnostics
OD Over Drive
ORC Organic Rankine Cycle
OTR Over The Road
PM Particulate Matter
PTO Power Take-Off
SCR Selective Catalytic Reduction
TCO Total Cost of Ownership
VGT Variable Geometry Turbocharger
WHR Waste Heat Recovery
128
ICPC 2019 – 6.2
Value Creation in the Commercial Powertrain Industry
Dr. Albert Neumann, Jana Mühlig, Xaver Müller
Strategy Engineers
Copyright © 2019 AVL List GmbH, Strategy Engineers and SAE International
ABSTRACT
The commercial vehicle industry is about to change significantly in the upcoming years. While the traditional diesel dominated world will still generate main revenues and profits, future value creation needs to be based on new technologies and businesses. Electrification, Connectivity and Autonomous Driving can all be part of this value creation but not without risks as major investments are required to create the foundation for a profitable implementation. In this paper, we discuss how the traditional world will develop and how operational improvements are mandatory to maintain current profits. The main focus is on reviewing challenges and opportunities for the new technologies. For the three trends Alternative Powertrains, Connectivity and System Solutions as well as Autonomous Driving, we present our view of major risks and opportunities and how we believe the
future in the commercial vehicle (CV) industry will develop.
INTRODUCTION
In the past years, the global sales for commercial vehicles (comprising of light-duty, medium-duty, heavy-duty trucks and city busses in the course of this paper) have been growing steadily. But this growth will slow down when looking at published forecast data (compare Exhibit 1).
Back in the year 2000, the truck market was growing at a compound annual growth rate (CAGR) of almost 5%. This growth was interrupted in the late 2000’s by the financial crisis. Since recovery, the market has grown at a CAGR of over 2% until today. Looking forward, we expect future transportation demand to be still growing but at low rate of approximately less than 2% annually.
Exhibit 1: commercial vehicles sales volume in units, worldwide, based on [1]
2000 20102005 20302015 2020 2025
+4.5%
+2.1%
+1.8%Before
financial crisis
Today
Future
CAGR City bus Light-duty truck (<3.5 t)Medium-duty truck (< 11.8 t)Heavy-duty truck (> 11.8 t)
ICPC 2019 – 6.2
129
Looking towards 2030, the profit structure of commercial vehicle companies can be divided into two key areas: traditional business and new opportunities (compare Exhibit 2).
In the first area of traditional business, we see a price pressure across the industry due to lower growth rates and through new competitors which will lower margins and hence generate less profits. At the same time, commercial vehicle companies are and will continue to improve their operational excellence, such as optimization of product costs and internal processes.
Exhibit 2: Profit structure of commercial vehicle companies (illustrative), in EUR, based on [2]
All in all, we believe that commercial vehicle companies are capable of outperforming the external factors and increase their profits based on the operational excellence improvement.
Besides the traditional business, we see – and this is what this paper is all about – new opportunities which have the potential to significantly improve overall profits. The areas in which these profits can be obtained are:
I - Alternative Powertrains
II - Connectivity and System Solutions
III - Autonomous Driving
In the following chapters, these three trends are covered in more detail. Technology trends, practical examples arising opportunities but also challenges are discussed.
I - ALTERNATIVE POWERTRAINS
As seen in the passenger car industry, the main driver for alternative powertrains in the commercial vehicle industry are legislative frameworks and zero emission zones.
The city of London serves as a practical example in setting strict targets to reduce the local transport emissions in the city. In the capital of the United Kingdom, the government is gradually installing and aggravating Ultra Low Emission Zone (ULEZ) and Low Emission Zones (LEZ). In those zones, only vehicles complying with strictly defined emission standards are allowed, otherwise heavy fines are due - especially for commercial vehicles. Regarding the city bus fleet, the city’s target is to have a fully zero emission fleet by 2037. An investment of £300 million is planned by the mayor of London to transform the bus fleet including retrofitting thousands of buses and phasing out pure diesel double-deck buses from 2018 onwards. [3]
London only serves as one practical example. In fact, almost every larger city in the world is aiming at improving their air quality. Especially city busses and light-duty trucks that operate in or close to the city centre are expected to be influenced by these developments.
Besides restricted emission zones, overall CO2 efficiency of diesel engines is becoming increasingly challenging and other alternative powertrains (hydrogen/fuel cell, hybrid, synthetic fuels, biofuels) are likely to gain importance in achieving emission goals. Exhibit 3 shows our forecast on the upcoming distribution of alternative powertrains by vehicle type.
Exhibit 3: Powertrain forecast for commercial vehicles, share of new sales (volume) worldwide [1]
Today 2030
Traditional business
Mark
et and
Macr
oeco
nom
ics
Opera
tional
Exc
ellence
New opportunities(focus of this article)
Altern
ative
Pow
ert
rain
s
Connect
ivity
and
Sys
tem
Solu
tions
Auto
nom
ous
Dri
ving
1%28%
2018
14%
2030
City bus LD truck(<3.5 t1)
HybridDiesel / Petrol Electric & Fuel Cell
23%
13%3%
20302018
7%
168k 7.4M
MD truck(< 11.8 t1)
HD truck(>11.8 t1)
2018
23%2%
2030 2018 2030
0.3%
0.1%0.3%
1.0M 11k
ICPC 2019 – 6.2
130
The application of alternative powertrains depends on use case and timing. We see battery electric vehicles to be the superior technology in distribution and city-centric use cases. Fuel cell propulsion will be a strong contender as it is best suited for heavy-duty transport segments that require long haul range and high utilization. Main factors are higher energy density, lower weight and faster re-fuelling. The success of CNG/LNG as well as synthetic fuels and biofuels will heavily depend on market price. This is subject to the availability of renewable energies and resources.
Now, the main question is, how this can lead to more profit for CV companies. The answer is to be found in the different use cases and legislation restrictions, making these technologies more or less attractive for customers. In any case, the overall TCO and/or usability of the product will make the difference. Then, it is important that despite increasing material and product cost, the offer to the client is attractive.
We strongly believe that there is an opportunity to charge the customer for these new technologies. Because of this, CV companies are still able to generate add-on profit from alternative powertrains despite higher material costs.
As shown in Exhibit 4, we expect the additional value creation to be approximately 5.7% until 2030.
Exhibit 4: Expected value creation in propulsion technologies of commercial vehicle companies, in EUR share [4]
As already indicated, a number of challenges have to be met in order to achieve this additional profit. The key challenges can be clustered along three different areas and cover the entire value chain from development to production and operations (see Exhibit 5).
Due to the fundamentally different technologies, CV companies must build up new E/E competencies required for electric-driven vehicles. Development competencies in e.g. batteries, e-motors, inverters or power electronics is key to successful product
creation. Along with this, it is essential to define a new set of modular architectures that can be applied across different applications. In the field of production, companies have to verify their make-or-buy strategy as some components may be outsourced and others will be produced inhouse for competitive advantage. This also requires setting up a new supplier base. On the operational level, standardized hardware and software interfaces as well as an easy access to charging infrastructure need to be established. Furthermore, aftersales support to customers is key as these new technologies may require additional accessories such as intelligent switchboards or battery monitoring.
Exhibit 5: Key challenges in the area of Alternative Powertrains
II - CONNECTIVITY AND SYSTEM SOLUTIONS
The next big area with great potential to increase the profit potential in upcoming years is what we generally name as connectivity. This can be services very close to the traditional business and products such as applications for fleet operators to manage, maintain and optimize their fleet, but can also reach to areas beyond the core business into service portfolio extensions with data-based business solutions. The competition in these areas is quite divers as new players are moving in, trying to capture part of the overall future value chain of transport (see Exhibit 6).
A great example for a connectivity platform is RIO, a digital brand established by the TRATON Group in 2017. Companies like Scania, MAN, Continental, Meiller Kipper or Schmitz Cargobull are already using the open connectivity platform to manage their vehicle fleets. In form of a box, RIO can be retrofitted to trucks from every manufacturer and can be used to control single trucks of the fleet, to determine the vehicles’ positioning, for intelligent routing and route
24%
72%
12%4%
20302018
24%
64%
+5.7%
+0.5%
-0.5%
+9.4%
CAGR
Battery electric drive components
Combustion engine components
Gearbox and differential
Opera
tion
Pro
duct
ion
Deve
lopm
ent
Verify their make-or-buy decisions
Set up a new supplier base
Restructure their manufacturing capabilities
Standardizehardware and software interfaces
Broaden their infrastructure
Gain new E/E competencies
Define new electrical product platforms
ICPC 2019 – 6.2
131
analysis, to plan and optimize maintenance of the whole fleet and to analyse performance of the vehicles.
Exhibit 6: Players in the connected commercial vehicle market, non-exhaustive exemplary selection
This is only one example and we expect 80-90% of the global fleet to be “connected” in 2030, at least in Europe and NAFTA. The challenge is how to use connectivity for new or extended business models and hence increase the overall profit for CV companies.
There are three different areas of services that we see on the market, based on their proximity to the commercial vehicle (see Exhibit 7).
Figure 7: Value adding services for connected commercial vehicles
The first stage are vehicle-integrated services, where the value add relates to the vehicle itself. This includes basic features such as navigation, infotainment or fuel management functions. The next stage is to offer a commercial vehicle related portfolio of services that benefits the customer retention. This includes e.g. fleet management, maintenance, driver analysis or digital payment functions. All the functions of the first two stages are mainly standard and part of the portfolio of all companies - there is very little differentiation potential. The objective for any CV company should be to develop and market services that go beyond the vehicle and cover additional elements of the transport value chain. This can be applications for load capacity sharing, truck sharing, aftersales or other digital services offered to transport operators.
To develop, implement and manage digital services, CV companies must manage a vastly different business compared to today’s core business. It requires different people with different skills, methods and processes (see Exhibit 8).
Exhibit 8: Key challenges in the area of Connectivity and System Solutions
The development of any digital service requires in-depth customer understanding and fast realization. Application and software development capabilities are key to be successful. Developing software calls for a new and independent software development process with shorter product development cycles and continuous product updates. Connected with that, agile working methods have to be set up and clear synchronisation points between the traditional hardware based and software development have to be defined.
Connected vehicles will produce a significant amount of data that a future E/E architecture needs to cope with. Data needs to be handled onboard within the car
traditionalCV companies
newCV companies
logisticsproviders
tier Isuppliers
fleetmanagement
providers
telematicsservice
providers
techgiants
Opera
tion
Pro
duct
ion
Deve
lopm
ent
Develop new supplier management
Enable on-/offboard computing
Offer flexible/efficient updatability
Shorten their product development cycles
Set-up agile workingmethods
Gain SW development knowledge
Establish partnering models
Think customer-centric
Re-positionwithin the value chain
Build-up reliable data protection
Extend customer contact
ICPC 2019 – 6.2
132
but also offboard, as cloud-based applications or on mobile computing devices.
Last but not least, a whole new concept for data security is necessary to manage digital services connected to vehicles or outside the vehicle perimeter.
III - AUTONOMOUS DRIVING
Autonomous driving aims to enable unmanned driving of trucks and will heavily influence the truck business in the future.
TuSimple, a California-based start-up, already operates 12 autonomous trucks on Arizonan streets and aims to increase this number to 50 until June 2019. The company which was founded in 2015 and operates from offices in San Diego and Peking raised over USD 178.1 million in four funding rounds and therefor gained unicorn status [5]. The Chief Product Officer Chuck Price mentioned that they “are confident that [they] will have [their] first commercial driverless operation in late 2020 to 2021” [6]. For safety reasons, their trucks are still manned with a system engineer and a driver but basically drive autonomously. The company just managed to get a public road test licence for Shanghai and by developing a new night camera, they accomplished to raise the daily utilization from 12 hours (50%) to 19 hours (80%) [7].
Another example from the conventional commercial vehicle industry is Volvo trucks which operates six autonomous mining trucks in a Norwegian limestone extraction mine. The trucks from the type Volvo FH 16 are controlled by a wheel loader operator using a site management system and are currently in test mode. Volvo trucks plans to operate the autonomous trucks 24/7 autonomous from autumn 2019 on [8]. Another innovator is Nikola, a US based start-up company which not only announced fully autonomous
unmanned trucks by 2022-2023, but also intends to use fuel cell powertrains in their vehicles.
As shown in Exhibit 9, we consider that autonomous driving will develop in different phases and that fully unmanned operation in all use cases will only be available far after 2030.
Autonomous trucks promise profit potential for OEMs as well as TCO optimization potential for their customers (see Exhibit 10). Main savings are expected from unmanned driving, but also through more fuel efficiency. Depending on the use case, this can sum up to 30% of TCO savings for the vehicle owners. Additionally, the annual mileage can be more than doubled due to higher utilization potential of driverless trucks.
Exhibit 10: Optimization potential through autonomous trucks, own calculation based on [9] and [10]
To succeed in autonomous driving technologies, commercial vehicle companies have to face different challenges, as shown in Exhibit 11.
The key challenge is the development, validation and homologation of assisted and autonomous driving functionalities. This not only requires skilled software developers and capable partners for both development and validation, but also a new E/E
291
Non-
autonomous
HD truck
Autonomous
HD truck
113
TCO compositionin thousand EUR per HD truck
Annual mileagein thousand km per year per HD truck
800
Other
Fuel
Non-
autonomous
HD truck
Driver
Autonomous
HD truck
Acquisition
560-30%
x 2.6
Exhibit 9: Roadmap of autonomous commercial vehicles
2015 2020 2025 2030
Autonomous trucks will first be established in geo fenced, confined areas
Fully autonomous drivingwithout geo restrictions
far after 2030
High automation on selected highways
High automation in confined areas
Full automation without geo restrictions
Partialautomation
unmanned operation in all use cases
ICPC 2019 – 6.2
133
architecture with high performance processors. In contrast to mechanical architectures, E/E architectures can be cost-efficiently used across various derivatives.
Exhibit 11: Key challenges in the area of Autonomous Driving
CONCLUSION
Commercial vehicle companies are facing a challenging time with traditional markets still growing but at lower pace. Maintaining current profits is key and can only be managed with continuous improvement of operational excellence.
New technologies and business development offer a great chance to add additional profits to the existing core business. However, this requires a significant change in all areas of a company.
We see four main tasks for CV companies: New value chains, new business models, new competencies and new vehicle platforms. All four have to be tackled simultaneously in order to succeed in Alternative Powertrains, Connectivity and System Solutions and Autonomous Driving (see Exhibit 12).
Transforming value chains require the CV companies to re-think their value chain positioning in forms of e.g. vertical integration. They also need to reconsider their make-or-buy strategy when it comes to manufacturing of hardware components. A changing supplier base will also require new partnering models through the three fields.
Emerging business models call for a change of mindset inside commercial vehicle companies. They have to implement an expanded service offering portfolio and tackle product digitalisation under close consideration of their customer (customer centrism).
New competencies are required throughout all three growth fields. Synergies can be drawn from building-up E/E know-how, promoting software development skills and respective methods and enhance manufacturing capabilities.
Exhibit 12: Main tasks for commercial vehicle companies
Changing vehicle platforms move away from mechanical-based platforms to electrical-driven platforms and require modular E/E architectures as well as standardized interfaces of hard- and software.
REFERENCES
[1] IHS Markit Vehicle Industry Forecast, 2018
[2] McKinsey&Company: “Route 2030 – the fast track to the future of the commercial vehicle industry”, September 2018
[3] Mayor of London / London Assembly – Transport: “Green Transport”, 2019
[4] VDMA, Forum Elektromobilität: “Antrieb im Wandel”, March 2018
[5] TuSimple Media page via Forbes: “First Robo-Trucking Unicorn? TuSimple Delivers $95 Million Funding Round” by Alan Ohnsmann, February 13, 2019
[6] The Wall Street Journal, Logistics Report: “Self-Driving Truck Tech Startup TuSimple Raises $95 Million in New Funding” by Jennifer Smith, February 13, 2019
[7] TuSimple Media page via VentureBeat: “Driverless trucks ride at night with TuSimple’s improved camera system” by Seth Colaner, March 19, 2019
[8] Volvo Trucks Magazine, Business Story: “Autonomous trucks in real operation” by Alastair Macduff, February 20, 2019
[9] Statista.de
Opera
tion
Pro
duct
ion
Deve
lopm
ent
Harmonize legal frameworks
Establish partnershipswith tech companies
Clarify TCO benefits
Build effective cyber security
Monetize their autonomous features
Set-up an agile SW development approach
Develop a flexible, modular E/E architecture
New competencies
New business models
New value chains
New vehicle platforms
ICPC 2019 – 6.2
134
[10] “Analysis of long haul battery electric trucks in EU” by Earl, Mathieu, Cornelis et al., originally presented in “8th Commercial Vehicle Workshop, Graz”, May 17-18, 2018
DEFINITIONS, ACRONYMS, ABBREVIATIONS
CAGR Compound Annual Growth Rate
CV Commercial vehicle
E/E Electrics/Electronics
OEM Original Equipment Manufacturer
TCO Total Cost of Ownership