exhaust gas recirculation and control - kuvatevvk.1g.fi/temp/yhyy/pb_kombi_agr_en_low.pdf ·...

Exhaust gas recirculation and controlwith Pierburg components

pb_kompi_agrV9_EN.indd 1 04.09.13 21:58

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Pierburg components for exhaust gas recirculation and exhaust gas control

Lowering fuel consumption and reducing pollutant emissions – in conjunction with optimising performance, comfort and safety – is of growing importance in the de-velopment of new engine generations. A catalytic converter or a diesel particulate filter used with a combustion engine cannot cope with this task alone.

Pierburg GmbH, part of the KSPG Group, is a specialist in the areas of emission control, air supply and throttle valves. Its decades of experience and comprehensive, innovative and renowned expertise when it comes to engines provide ideal foundations for Pierburg in the ongoing development and production of pioneering components, modules and systems. In addition to other

concepts, the manufacturer also offers technology for exhaust gas recirculation (EGR) and exhaust gas control: this can be used to meet the current limit values prescribed by legislation and future requirements on national and international markets in an efficient manner.

Although raw emissions from engines can be continually reduced with technical measures, the tightening of emission limit values also means that technologies in non-engine measures must be improved. Consistently developed, state-of-the-art EGR concepts also make a valuable contribution to more effective use of fuels. On top of this, they support the engine during the warm-up phase, with flap systems also bringing it to the required operating temperature more quickly.

Fig. 1: Compact EGR valve


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With various components and modules, supported by pneumatic or electrical actuators, Pierburg can provide its customers with optimum EGR components for future engine applications too. The engine specialist offers a modular system that can be used to create the ideal customer solution.

Due to strict emission limit values that are constantly beingtightened, the technical requirements for EGR components are also becoming increasingly demanding in terms of control in higher-level engine systems. The resulting high degree of mechanical and electronic integration of function groups leads to “tailor-made” mechatronic EGR components.

Pierburg EGR valves and exhaust gas fl aps feature excellent responsiveness and control and positioning accuracy at high actuating forces. The use of EGR valves in conjunction with an EGR cooler and exhaust gas fl aps for controlling the pressure difference enables a signifi cant reduction in nitrogen oxides.

Overall, the intelligent integration of all EGR components such as valves, fl aps, bypasses, coolers and lines offers a cost-effective solution with excellent durability that protects the environment.

How exhaust gas recirculation works

Exhaust gas recirculation reduces nitrogen oxide emissionsin both diesel and petrol engines right at the formationphase by lowering the combustion temperature and reducing the oxygen content in the intake air.

Exhaust gas recirculation is not only used to minimise nitrogen oxides; it is also used in petrol engines to reduce fuel consumption.

Due to the lean operation of diesel engines, these can handle much higher exhaust gas rates than petrol engines.

Fig. 3: EGR module

Fig. 2: EGR ranges of conventional petrol and diesel engines

Speed [rpm]

Load

[%]

EGRrangepetrolEGR

rangediesel

Full loaddiesel

Full loadpetrol

100

80

60

40

20

01000 2000 3000 4000 5000 6000


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Fig. 4: Emissions legislation (selected areas) for Europe, America and Asia

Exhaust gas recirculation in diesel engine applications

In diesel engines, oxidation catalytic converters and particulate fi lters are used to reduce hydrocarbons (HC) and particulate matter (PM). To reduce NOx in diesel engines, exhaust gas recirculation has become established as a well-engineered and cost-effective technical solution alongside measures in the engine such as injection start timing.

Due to the continual tightening of NOx limit values, urea catalytic converter exhaust gas after-treatment systems (SCR) and NOx storage catalysts are used in addition to EGR.

By signifi cantly reducing the temperature of the recirculated exhaust gas, EGR cooling makes exhaust gas recirculation more effective and therefore further reduces nitrogen oxides.

Exhaust gas recirculation in petrol engine applications

In petrol engines, exhaust gas recirculation is used to dethrottle the engine in the part-load range. This leads to a reduction in fuel consumption.

Depending on the petrol engine concept, the EGR rates can be increased. Petrol engines with direct injection in stratifi edcharge operation have the highest EGR rates (lambda > 1; see Fig. 2).

As lean operation of petrol engines with direct injection means that three-way catalytic converters cannot be used, the highest possible EGR rates are required to reduce the raw emissions of nitrogen oxides. With exhaust gas recirculation, the nitrogen oxides in the raw exhaust gas are reduced down to 70 % and the air fl ow is also reduced signifi cantly. The reduced frequency of DeNOx catalytic converter scavenging due to the lower raw emissions also indirectly benefi ts fuel consumption. Future concepts may contribute to increased engine effi ciency by reducing the engine’s knocking tendency in the high-load range.

Country/Year‚00

‚01

‚02

‚03

‚04

‚05

‚06

‚07

‚08

‚09

‚10

‚11

‚12

‚13

‚14

EU Euro 2 Euro 3 Euro 4 Euro 5 Euro 6

Hong Kong, China Euro 2 Euro 3 Euro 4

India (petrol) India 2000 / Euro 1 Bharat Stage II / Euro 2 Bharat Stage III / Euro 3

India (diesel) Bharat Stage II / Euro 2 Bharat Stage III / Euro 3 Bharat Stage IV / Euro 4

PR China (petrol) Euro 1 Euro 2 Euro 3 Euro 4

Turkey (petrol) Euro 1 Euro 4

Turkey (diesel) Euro 3 Euro 4

Russia Euro 1

CIS States Euro 2 Euro 3 Euro 4

USA Tier 1 Tier 2 Tier 3

Canada Tier 1 Tier 2 Tier 3

Mexico SEMARNAT 2003/Tier1 Tier 2 /Euro 3, 4 equivalent


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National and international emissions requirements

Legislation is continually tightening emissions requirements to limit the environmentally damaging infl uence of fossil fuel combustion in engines.

Combustion produces end products such as carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM), sulphur dioxide (SO2), sulphuric acid (H2SO4) and many more. The fi rst common European emission standards were introduced in the 1970s for cars. The values for carbon monoxide (CO) and hydrocarbons (HC) were restricted. In 1977, nitrogen oxides (NOx) were also restricted. The limit value for soot particulates (PM) was introduced for diesel engines in 1988.

Vehicles are assigned to specifi c emission classes using the limit values. Among other things, these emission classes are used to calculate vehicle tax and in pollutant group classifi cation for low-emission zones. With the limit values,

distinctions are made between diesel and petrol engine combustion types and between the vehicle types of cars, trucks and motorcycles.

In addition to the European emission standards (Euro 1 – 6), other national standards also exist, which must be taken into account in the relevant countries. In the USA, various emission standards (Tier 2 EPA limit values, LEV II CARB limit values) have been introduced. The EU and the USA arethe driving forces for emission standards. Most countries is Asia and North and South America adopt the EU and US emission standards. Motor vehicle manufacturers must therefore take the various limit values into account at different times.

Fig. 5: Development of pollutant limitation for vehicles withdiesel engines

Fig. 6: Development of pollutant limitation for vehicles withpetrol engines

Euro 4

Tier II, Bin 8

ULEVSULEV

Euro 3

Euro 5Euro 6Euro 6

Tier II, Bin 5Tier II, Bin 5Tier II, Bin 5Tier II, Bin 5Tier II, Bin 2

0 0,1 0,2 0,3 0,6

0,05

0,04

0,03

0,02

0,01

0

HC + NOx (EU) [g/km] / NOx (US+Cal.) [g/mi]

Part

icul

ate

mat

ter (

EU) [

g/km

] / (U

S) [

g/m

i]

HC

(EU

) [g/

km] /

HC

exce

ptio

n m

etha

ne (U

S) [

g/m

i]

NOx [g/km] / NOx (US+Cal.) [g/mi]

Euro 4

Tier II, Bin 8

LEV

Euro 3

Tier II, Bin 2Tier II, Bin 2Tier II, Bin 2SULEV

Tier II, Bin 2Tier II, Bin 2Tier II, Bin 2

ULEV

Euro 4Euro 5

0,2

0,15

0,1

0,05

00 0,1 0,2

Diesel engine Petrol engine


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• Excellentreliability• Durabilityandrobustness• Highresistancetocontamination• Smallinstallationvolumeandlowweight• Hightemperatureresistance• Lowlevelsofleaks• Diagnosticcapability• Lowsystemcosts

In terms of design, functionally equivalent electromotive EGR valves are used for intake manifold petrol engines and direct injection (DI) petrol engines. EGR valves for petrol engines are characterised by components with high resistance to thermal loads and to contamination. Larger valve cross sections are also typical in EGR valves for DI petrol engines in lean operation.

EGR valves for applications in high-load high-pressure(HP) and low-pressure (LP) concepts

Stricter CO2 regulations and the associated requirement to reduce fuel consumption are set to trigger a greater shift of emphasis for exhaust gas recirculation in the direction of high loads. Pierburg provides solutions for high-load EGR systems, which are being increasingly used in petrol engines with supercharging in particular.

CO2 and climate change

In the 1990s, the EU Commission published its strategy for reducing CO2 emissions from cars and lowering the averagefuel consumption. On the basis of this, manufacturers committed, on a voluntary basis at fi rst, to reduce CO2 emissions in line with the EU specifi cations, with the average emission limit being set at 140 g/km.

However, when the average CO2 emission per car was around 20 g/km above the target value set for 2009, the EU decided to take statutory measures. As a result, the Commission lowered the limit values for average CO2 emissions per car continually and set a target of 95 g/km for 2020.

Petrol EGR concepts

EGR valves for applications in part load

Exhaust gas recirculation in part load has become establishedin engines with manifold injection and is used to some extent for engines with direct injection. Future emissionlimits such as the limit value of 95 g CO2/km, demand specifi cally tailored external exhaust gas recirculation systems in modern petrol engines. The function of an exhaust gas recirculation system is determined centrally bythe layout of the EGR components. For this reason, EGR components must be designed on an individual basis for the application. Based on its many years of experience with EGR valves, Pierburg has developed electrical EGR valves for petrol engines that excel through the following characteristics:

• Excellentdynamics• Highcontrolquality/goodmeteringacrossthe fl ow rate range• Goodmixingofexhaustgasandfreshair thanks to specifi cally adapted housing• SufficientEGRratesinthedesiredloadrangeand exhaust gas back pressure range

Fig. 7: Petrol HP EGR and LP EGR concepts

Petrol engine

1000 2000 3000 4000 5000 6000

100

80

60

40

20

0NEDCPart-load EGR

WLTP

High-load EGR

Speed [rpm]

Load

[%]

Knock limit


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As can be seen in the schematic depiction of an engine map (see Fig. 7), EGR is used in two ranges.

In the part-load range, non-cooled EGR is used for dethrottling and therefore produces a reduction in fuel consumption.

Due to increasing loading pressures in the high-load range, the compression ratio of the engine must also be reducedin order to reduce the knocking tendency of the engine that is caused by these. However, this in turn lowers the effi ciency of the engine.

To counteract this (i.e. to maintain the compression ratio or even to increase it), cooled LP EGR is used in the high-load range at low engine speeds, alongside ignition timing adaptation.

The application range of EGR may be expanded in future into the high-load range for higher engine speeds. To do this, LP EGR and HP EGR modules with high cooling performance need to be integrated in the engine design. Here too, the

Fig. 8: High-pressure exhaust gas recirculation

aim is to reduce the knocking tendency at high loading pressures and a simultaneous high compression ratio.

In contrast to EGR valves, which are used in the high-pressure range, butterfl y or high-fl ow valves can be used in the low-pressure range – in a similar manner to in diesel engines.

Diesel EGR concepts

There are various positions for exhaust gas removal depending on the application. The classic method of removing exhaust gas from the engine upstream of theturbine and feeding it back into the fresh air is known as high-pressure exhaust gas recirculation (HP EGR). With low-pressure exhaust gas recirculation (LP EGR), the exhaust gas is removed downstream of the turbine and fed to the compressor at a low pressure level. The mixing of the exhaust gas and the fresh air via the compressor is at an optimum for the engine.

Fig. 9: Low-pressure exhaust gas recirculation

ETC

IntegratedCA & EGR cooler

C T

EGRvalve

Cat

HP EGRETC


C T

LP EGR valve

Pre-cooler

Cat

Petrol engine HP EGR

LP EGR

Petrol engine LP EGR


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EGR valves for diesel high-pressure concepts

In this case, the exhaust gas is removed directly at the exhaust manifold and fed through a tube at a high pressure level to the fresh air side. The exhaust gas and fresh air mix in the intake manifold or boost pressure tube.

The recirculated exhaust gas is added to the mix by an exhaust gas recirculation valve located on the engine.

The recirculated exhaust gas reaches a temperature of approx. 400 °C to 600 °C. Exhaust gas recirculation valves must be securely sealed against the exhaust gas back pressure and the boost pressure. They must also be resistant to soiling, soot contamination and harmful condensates, which can lead to corrosion.

Diesel HP EGR valves generally need to have:

• Excellentadjustmentdynamics• Good metering• Definedcharacteristiccurve• Resistancetocontamination

• Robustnessanddurability• Diagnosticcapability• Flexibledesignforthevariousinstallationspaces• Lowweight• Lowcosts

HP EGR valves generally have a non-contact stroke sensor. The engine control unit can use this sensor information to adjust the desired valve stroke – and therefore the required exhaust gas recirculation rate – in a closed control loop. If necessary, the sensor information can be used for EGR valve diagnostics.

HP EGR poppet valves

Electromotive EGR valves, or EM EGR valves, are used in diesel engines. The shut-off component of the EGR valve is a valve poppet, which is opened with or against the direction of flow, depending on the design. A DC electric motor with downstream gearing is used as the drive. The rotary motion is transformed into a linear motion via an eccentric drive. Reversing the direction of rotation of the DC electric motor provides motor support to the closing force. This produces quicker and more reliable closing with low valve seat leakage. EM EGR valves are characterised by excellent adjustment dynamics and at the same time, high actuating forces. Single poppet valves are robust and resistant to contamination. Lower pressure losses and high flow rate can be seen in particular in EM EGR valves that open in the direction of flow. The compact EGR valve provides an especially space-saving model.

Both the standard EM EGR valve, which is more consistently modular, and the compact EGR valve are particularly lightweight.

Fig. 10: Diesel EGR Gen. II valve


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EGR valves for diesel low-pressure concepts

In order achieve the higher exhaust gas recirculation rates needed to meet the Euro 6 exhaust gas regulation, low-pressure exhaust gas recirculation (LP EGR) will in future beused increasingly in turbocharged engines in addition to theestablished high-pressure exhaust gas recirculation (HP EGR). In this process, the exhaust gas is rerouted downstream of the diesel particle fi lter (DPF) and returned upstream of the compressor. The required scavenging gradient is set by supplementary engine throttling. Pierburg offers the required fully electronic individual components for the exhaust gas recirculation section, such as EGR valves, throttle valves and exhaust gas fl aps, as well as complete EGR cooler modules for this process.

An LP EGR valve controls the exhaust gas recirculation rates through continual adjustment of the fl ow cross section.

Pierburg develops appropriately adapted LP EGR valves for this and other desired functions and requirements of our customers operating around the world.

LP EGR butterfl y valve

The Pierburg butterfl y valve consists of an aluminium pressure die-cast housing with a central butterfl y valve and an integrated actuating drive, made up of a direct current motor and a two-stage spur gear unit.

The tried-and-tested assembly groups for the LP butterfl yvalve were developed from existing throttle valves and EGRvalve assembly groups, which had already been in series production for many years. This guarantees a perfectly tailored solution for the customer.

ETC


C T

EGRvalve

LP EGR valve

ECVPre-cooler

Oxi-CatDPF

NOx

HP EGR

ETC


C T

EGRvalve

LP EGR valve

Pre-cooler

NOx

HP EGR

LP EGRsystem

LP EGRsystem

Oxi-CatDPF

Diesel engine LP concept I

Diesel engine LP concept II

Fig. 11: Combination of EGR valve + exhaust gas fl ap

Fig. 12: Combination of EGR valve + throttle valve


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Fig. 14: Low-pressure butterfl y valve

Tab. 2: Typical values for a butterfl y valve with 35 mm Ø

Fig. 13: Diesel EGR Gen. II valve

Tab. 1: Typical values for an HP poppet valve with 25 mm Ø

Max. fl ow rate 150 kg/h at Δ 50 hPa

Internal leakage < 3 kg/h at 600 hPa

Max. ambient temperature -400C to +1500C

Typical exhaust gastemperature

1600C

Nominal currentconsumption

1 amp

Permissible vibrationacceleration

20 g

Weight < 0.7 kg

Actuation frequency 1 to 10 kHz

Position feedback Non-contact sensor

Installation position -850 to +850

Specifi c characteristics

• Corrosion-resistant materials

• Low installation weight• High torque at the fl ap• EGR rate precisely controllable• Flap is pressure balanced


Internal leakage, valve seat < 0.5 kg/h at 600 hPa



4000C to 6000C (with water cooling)


1.1 amp


25 g

Weight < 0.7 kg



Installation position Vertical -850 to +850


• Excellent dynamics• Small installation volume• Low weight• High temperature

resistance• Low leakage• Modular construction method


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Fig. 16: Compact EGR valveFig. 15: High-fl ow EGR valve

Tab. 3: Typical values for a wastegate EGR valve with 35 mm Ø Tab. 4: Typical values for a compact EGR valve with 25 mm Ø


Internal leakage < 0.5 kg/h at 600 hPa



1600C


1 amp


20 g

Weight < 0.85 kg



Installation position -850 to +850


• Corrosion-resistant materials

• Low installation weight• High torque at the fl ap• EGR rate precisely controllable• Low pressure loss• Low leakage


Internal leakage, valve seat < 0.5 kg/h at 600 hPa



4000C to 6000C (with water cooling)


1.2 amp


20 g

Weight < 0.6 kg



Installation position Vertical -850 bis +850


• Excellent dynamics• High EGR rates• Small installation volume• Low weight• Temperature resistance• Low leakage


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LP EGR high-fl ow valve

The high-fl ow EGR valve from Pierburg is characterised in particular by the fl ow cross section that is fully released when open and a design principle resulting from this that is optimised for loss of pressure. Compared to the butterfl yvalve, this design has considerably less leakage when closed.

LP EGR poppet valve

The EGR poppet valve from Pierburg is now also used in the low-pressure range. Here, the advantages from the high-pressure range are transferred to the low-pressure range, such as the compact construction method and low leakage for example.

Exhaust gas fl ap

If the pressure gradient in the low-pressure system is insuffi cient to control the required EGR mass fl ow rate, an electrical Pierburg exhaust gas fl ap is used to generate ram pressure.

The exhaust gas fl ap can be adjusted between the “open” and “closed” positions with continuous electromotive adjustment. This enables a defi ned pressure build-up in theentire adjustment range and as a result, controlled exhaust gas recirculation and pollutant reduction. The fl ap positionresponse is sent via a non-contact angle sensor; in the case of a de-energised drive, it is automatically set with spring-loading to the “open” emergency running position. Its actuators are designed as a modular system and whilst they have the same range of functions, they vary in terms of fl ange size, attachment geometry and fl ap diameter. The electromotive exhaust gas fl ap can therefore be adjusted to the dimensions required in each case, according to the installation space for various vehicle types and exhaust systems.

Fig. 17: Exhaust gas fl ap

Tab. 5: Typical values for an exhaust gas fl ap with 55 mm Ø


Internal leakage < 50kg/h at 600 hPa



6500C


1 amp


5 g

Weight < 950 g



Installation position -50 to -450


• Corrosion-resistant• Heat-resistant• Lightweight design• High torque


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Fig. 18: Combi valve

In 2007, Pierburg developed the fi rst electromotive exhaust gas fl ap for the NAFTA market with a precision-cast housing.Today, the further-developed exhaust gas fl ap has a lightersheet metal design. The use of high-quality materials means that the fl ap can be operated in even the most challenging environmental conditions. On the one hand,the high resistance to corrosion enables use directly in the exhaust system, which is subject to a particularly high degree of soiling from outside and within due to prolonged exposure to corrosive exhaust gas products. On the other hand, high-strength material ensures seamless function for the electrical fl ap, even at high exhaust gas temperatures.

Pierburg exhaust gas fl aps are also used in the area of soundshaping.

LP EGR combi valve

The combi valve assumes the tasks of the low-pressure EGR valve and the exhaust gas fl ap. In doing so, it controls the exhaust gas recirculation fl ow, assists control of the delivered exhaust gas fl ow and sets the required differential pressure. As a combined component, the LP combi valve is not only more cost-effective, but also offers the benefi t of a lower weight.

The valve is fi tted with a non-contact position sensor for position control. Together with an air mass sensor, this enables precise EGR control in all operating states. The valve is not sensitive to soot or particulate matter and is resistant to condensate. The drive and valve construction is particularly robust.

Tab. 6: Typical values for a combi valve with 30 mm Ø


Internal leakage < 3kg/h at 300 hPa



1600C


1 amp

Vibration resistance 5 g

Weight < 1,200 g



Installation position -850 to -850

Specifi c characteristics• Corrosion-resistant• Lightweight design• Multifunctional


++

+

+

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The use of a bypass fl ap means that the typical “diesel knock” at a cold start and the raw emissions of hydrocarbons(HC) in the engine’s warm-up phase can be reduced. With the bypass function, the engine and catalytic converter operating temperatures are achieved more quickly after a cold start.

EGR modules for the low-pressure range

For an engine design with a low-pressure EGR module, the exhaust gas is rerouted downstream of the diesel particulatefi lter (DPF) and returned to the intake air system of the engine upstream of the turbocharger compressor impeller. The exhaust gas is also cooled by a special low-pressure EGR cooler. The exhaust gas cooling provides thermal protection for the turbocharger compressor impeller. A typical LP EGR module consists of an LP EGR valve in conjunction with an EGR cooler.

Fig. 20: Diesel EGR valve with bypass fl ap and EGR cooler

EGR modules

EGR modules for the high-pressure range

EGR modules consist of an EGR valve, an EGR cooler to cool the exhaust gases and optionally, a bypass fl ap. Integrating these functions in one component produces advantageswhat it comes to size. Component interfaces and the number of sealing points are reduced. As a rule, having multiple individual components increases component costs, whereas a module can make a major contribution to cost reduction.

The bypass fl ap is used to regulate the controlled re-routing of the hot exhaust gas fl ow past the EGR cooler or, in the cooling position, through the EGR cooler. A pneumatically controlled actuator is used to operate the bypass fl ap. This means that at a cold start, the engine and catalytic converter reach operating temperature more quickly.

Fig. 19: EGR module versions

EGR valve

EGR valve

Bypass fl ap EGR cooler

Bypass fl ap

EGR valve EGR cooler


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Subject to change. Printed in Germany. © KSPG AG – 09/2013

Pierburg GmbH · Alfred-Pierburg-Straße 1 · 41460 Neuss · Germany Tel. +49 2131 520-01 · Fax +49 2131 520-645 · www.kspg.com


exhaust gas recirculation and control - kuvatevvk.1g.fi/temp/yhyy/pb_kombi_agr_en_low.pdf ·...

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