25072013082800 valvetronic engine

8/12/2019 25072013082800 Valvetronic Engine

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VALVETRONIC ENGINE TECHNOLOGY

1. INTRODUCTION

The automobile has been providing individual mobility for more than 100 years. This mobility

is made possible first and foremost by combustion engines drawing their power from fossil energycarriers, which, even today, provide the foundation in generating mechanical drive power in the

automobile. The primary objectives in developing drive systems are to curb fuel consumption and

reduce CO2 emissions. n an effort to meet this challenge, the automotive industry is developing

suitable new engines. The voluntary commitment assumed by the !uropean "utomobile #anufacturers

"ssociation $"C!"% is to reduce the fleet emission average of all newly introduced cars to 1&0g of CO2

per 'ilometer by 200( .

The first objective is to minimise emission components such as hydrocarbon, CO2 and

nitrogen o)ides $*O)% subject to specific limits. "t the same time, manufacturers are see'ing to

minimise fuel consumption and, accordingly, CO2 emissions. "ll of this should be achieved with a

ma)imum standard of comfort and safety on the road. n the homologation of motor vehicles, !urope,

+apan and the - apply different driving cycles to determine emissions and fuel consumption.

owever, it is the individual customer who ultimately decides on his/her particular style of motoring

and up to 0 of a cars fuel consumption depends on how it is driven and the style of motoring that

is preferred by the driver. Clearly, the development engineer is unable to influence these e)ternal

parameters 3 all that he/she can do is change the basic functions and control factors in the car and its

drivetrain. The amount of energy re4uired for driving a vehicle also drops with decreasing driving

resistance provided by, for e)ample, a reduction in roll and air resistance.

To ma'e more efficient use of the energy in fuel, the actual process of using energy must

reach a higher standard of efficiency.

5espite modern engine technology, the process of on6going development has not yet come

to an end. 7oo'ing at the overall concept of a vehicle, the development engineer must therefore

optimi8e the efficiency chain formed by all of the cars individual components. 9or e)ample, a car with

a state6of6the6art spar'6ignition engine uses only about 20 of the energy consumed to actually

generate driving power and mobility in the ! test cycle. This alone demonstrates the remaining

potential

2. VALVETRONIC

2.1. Evolution of Valvetronic

The losses that are capable of being influenced are composed primarily of the following:

a combustion process not yet ideal;

the charge cycle;

friction; and

thermal losses through the walls.

Optimisation in these areas in driving cycles with low loads and engine speeds provides the

greatest improvements in fuel economy.


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having a fle)ible concept capable of fulfilling future emissions standards;

creating a benchmar' product in terms of its pac'age, weight and cost of ownership;

ta'ing a modular approach in order to develop specific engine variants;

ensuring a significant potential for on6going development; and

providing the foundation for other engine variants, i.e. communality with future

engines.

"ll of this led to the development of a fully variable valve drive system, >#? @alvetronic,

helping to significantly reduce fuel consumption while maintaining stochiometric driving conditions

with all the usual advantages.

2.2. !"at I# Valvetronic$

The @alvetronic engine is the worldAs first engine without a throttle butterfly. @alvetronic

allows the engine to run without a throttle butterfly, the cylinder charge being determined under part

load as a function of the valve6opening period. The inta'e and outlet camshafts are driven by variable

cam adjustment, >#?s @anos technology. " further advantage of this concept is that it allows

worldwide use of the proven three6way catalyst for emissions management, thus meeting even the

strictest emissions standards in the -.

nnovative technology was essential in order to reach the demanding objectives and

functional re4uirements desired. owever, at the same time, this concept demanded the utmost of

the electronic control and management systems in the engine.

2.%. Conce&t

Ta'ing nature as the role model: human beings also apply the @alvetronic principle

" comparison with the human being clearly e)plains how @alvetronic wor's: ?henever we

are re4uired to ma'e a great effort, we human beings breathe in a deep and long process of

ventilation. ?henever we need less air, we do not throttle the supply of air by, say, closing our nose

or our mouth, but simply breathe in a shorter, flatter process of ventilation. n a conventionalcombustion engine the throttle butterfly is basically comparable to a human being 'eeping his nose or

mouth at least partially closed. ?ith its large valve lift $B deep, long ventilation% and short valve lift

$B flat, short process of ventilation%, @alvetronic, on the other hand, is able to breathe in the same

way as nature 3 always in line with current re4uirements, without any 'ind of throttling effect and

therefore with ma)imum efficiency.

2.'. Valvetronic Tec"nolo()

"ccordingly, the @alvetronic engine no longer re4uires a throttle butterfly, which has 4uite

literally restricted the free ventilation of the internal combustion engine ever since its invention. *ow

@alvetronic replaces this conventional function by infinitely variable inta'e valve lift, offering a

4uantum leap in technology 4uite comparable to the changeover from the carburetor to fuel injection.

ts most important feature is that it is able to save at least 10 per cent fuel throughout the

entire operating range relevant to the customer, with a corresponding reduction in e)haust emissions,

regardless of fuel 4uality. "nd a further important point is that the efficient operation of @alvetronic

does not re4uire any unusual types and grades of oil possibly difficult to obtain.

"s a result of these particular features the ( '?/11bhp >#? 1Dti compact with its top

speed of 210 'm/h or 12 mph consumes a mere D.E liters of premium fuel on 100 'ilometers in the

!uropean test cycle, e4uivalent to &0.E mpg mp. This is a significant 0.F liters less than the former

FF '?/10 bhp compact and well over a liter less than all competitors in this class.

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The @alvetronic system is based consistently on >#?s proven double6@"*O- $@"*O- B

variable adjustment of the camshafts%, with infinite camshaft adjustment to meet specific

re4uirements. The additional, variable valve lift adjusts the effective cam action and, accordingly, the

opening cross6section of the valves.

This is done by a lever positioned between the camshaft and the inta'e valves, its distance

from the camshaft being adjusted infinitely by an additional eccentric shaft operated by an electric

motor. 5epending on the position of the @alvetronic control system, the lever converts the cam

contour into a larger or smaller valve lift, whatever may be re4uired.

%. !OR*ING O+ VALVETRONIC ENGINE

%.1. !or,in( Of Or-inar) En(ine

n engines without valvetronic technology fuel injection systems monitor the volume of air

passing through the throttle butterfly and determine the corresponding amount of fuel re4uired by the

engine. The larger the throttle butterfly opening, the more air enters the combustion chamber.

"t light throttle, the throttle butterfly partially or even nearly closes. The pistons are still

running, ta'ing air from the partially closed inta'e manifold. The inta'e manifold between the throttle

and the combustion chamber has a partial vacuum, resisting the suc'ing and pumping action of the

pistons, wasting energy. "utomotive engineers refer to this phenomenon as Gpumping lossG. The

slower the engine runs, the more the throttle butterfly closes, and the more energy is lost.

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%.2. !or,in( Of Valvetronic En(ine

Compared with conventional twin6cam engines with finger followers, @alvetronic employs anadditional eccentric shaft, an electric motor and several intermediate roc'er arms, which in turn

activates the opening and closing of valves. f the roc'er arms push deeper, the inta'e valves will

have a higher lift, and vice6versa. Thus, @alvetronic has the ability to get deep, long ventilation $large

valve lift% and flat, short ventilation $short valve lift%, depending on the demands placed on the

engine.



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Cylinder heads with @alvetronic use an e)tra set of roc'er arms, called intermediate arms $lift

scaler%, positioned between the valve stem and the camshaft. These intermediate arms are able to

pivot on a central point, by means of an e)tra, electronicly actuated camshaft. This movement alone,

without any movement of the inta'e camshaft, can open or close the inta'e valves.

The @alvetronic system is based on >#?As established double @"*O- system, which

steplessly varies the timing of both the inlet and e)haust cams. owever, the @alvetronic system adds

variable valve lift to the inlet cam, achieved by the use of a lever positioned between the camshaft

and the inlet valves. @alvetronic varies the timing and the lift of the inta'e valves. The @alvetronic

system has a conventional inta'e cam, but it also uses a secondary eccentric shaft with a series of

levers and roller followers, activated by a stepper motor. >ased on signals formerly ta'en

mechanically from the accelerator pedal, the stepper motor changes the phase of the eccentric cam,

modifying the action of the inta'e valves. "n additional eccentric shaft alters the leverAs distance from

the camshaft, with the eccentricAs position determined by a worm drive from an electric motor. The

position of the lever converts the cam action into a smaller or larger valve lift, as re4uested by the

engine management system. nta'e vale lift can be altered from a minimum of 0.2mm$M% to a

ma)imum of E.Fmm, with the electric motor adjusting the eccentric shaft in 0. seconds.

>ecause the inta'e valves now have the ability to move from fully closed to fully open

positions, and everywhere in between, the primary means of engine load control is transferred from

the throttle plate to the inta'e valve train. >y eliminating the throttle plateAs Gbottlenec'G in the inta'e

trac', pumping losses are reduced, fuel economy and responsiveness are improved.

%.%. O&eratin( ara/eter#

@alve lift is variable between 0 and E.F mm.

"djustment of the worm gear from one e)treme to the other ta'es 00 milliseconds.

Combined with double6vanos valve timing technology, the camshaft angle relative to the

cran'shaft can be adjusted by up to D0N.

The intermediate arm is finished to a tolerance of 0.00( mm.

The cams controlling the eccentric shaft are machined to tolerances of a few hundredths of a

millimeter.



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'. ENGINE DE0IGN A0ECT0

'.1. a#ic en(ine -e#i(n co/&letel) revi#e-

*ot only the cylinder head with >#?s new @alvetronic technology, but also the complete

four6cylinder power unit featured in the >#? 1Dti is an all6new development from the ground up.

The new cross6flow cooling concept with its open dec' cran'case reduces coolant flow resistance and

therefore allows use of a smaller water pump with just D0 per cent of the usual power upta'e.

#ade of aluminum, the engine bloc' ends e)actly on the centerline of the cran'shaft

bearings. " ladder frame between the cran'case and the oil sump connects the lower halves of the

bearing bridges to form one complete unit also accommodating the balance shaft housing and the

two6stage oil pump. This ma'es the entire drive unit very stiff and robust, minimi8ing any vibration of

other vehicle components the driver would otherwise feel on the steering wheel, gearshift lever and

pedals, and also perceive as a 'ind of consistent humming noise.

"ll ancillaries are bolted directly to the cran'case without the rather elaborate supports and

attachments otherwise re4uired 3 again an important contribution to running smoothness with

vibrations reduced to a minimum.

'.2. T"rottle &late i# not re/ove-

t is important to note however, that the throttle plate is not removed, but rather defaults to

a fully open position once the engine is running. The throttle will partially close when the engine is

first started, to create the initial vacuum needed for certain engine functions, such as emissions

control. Once the engine reaches operating speed, a vacuum pump run off the passenger side e)haust

camshaft $on the *D2 @( only% provides a vacuum source, much as a diesel engine would, and the

throttle plate once again goes to the fully open position. The throttle plate also doubles as anemergency bac'up, should the @alvetronic system fail. n this case, the engine would enter a Glimp

homeG program, and engine speed would once again be controlled by the throttle plate.

. ADVANTAGE0 AND ENE+IT0

.1. +uel econo/) increa#e-

@alvetronic offers the customer direct, immediate benefits, with fuel consumption and

e)haust emissions decreasing, but dynamic performance and the spontaneous response of the engine

improving accordingly. "dded to this there is the even higher standard of running smoothness, since

the valves move only slightly in a precisely controlled process.

The improvement in fuel economy ensured by this concept of throttle6free engine load

management is appro)imately 10 per cent in the ! cycle and at least 10 per cent under the typical

driving conditions encountered by a customer. The basic rule is that fuel economy versus other

concepts increases with the driver running the vehicle at lower loads and engine speeds. The

consumption figures the motorist is able to achieve in this way are comparable to the fuel economy

only a diesel engine was able to offer just a few years ago.

"t the same time the new four6cylinder is even more dynamic than its predecessor, the 1Dti

now accelerating well over a second faster to 100 'm/h, achieving this important mar' from a

standstill in 10.E seconds. The standing6start 'ilometer, in turn, comes after 1.D seconds, 1.(



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seconds faster than before, and the top speed of the 1Dti is now 201 'm/h or 12 mph, 11 'm/h

faster than the top speed of the former model.

"nother advantage is the unusually spontaneous response of the 1Dti to the gas pedal. This

is attributable to the simple fact that load control, to use the technical term for Ggiving gasG, now

ta'es place Gright there where the action isG, that is directly in the combustion chamber. Thiseliminates the usual time lag between the process of Ggiving gasG and the actual acceleration of the

car, which used to be inevitable due to the need to fill the inta'e manifold between the throttle

butterfly and the combustion chamber. n this respect, @alvetronic even outperforms the most

advanced concepts using individual throttle butterflies, thus offering an unprecedented combination of

spontaneous engine response and ultra6fine dosage of power and performance under low loads.

.2. erfectl) #uite- for all fuel (ra-e#

"nother significant advantage of @alvetronic highly beneficial to the customer is that a

@alvetronic engine offers at least the same fuel economy as the most advanced direct6injection petrol

engines without the same compromises in terms of emissions. "ccordingly, the 1Dti is able to do

without the elaborate and so far hardly reliable emission management technologies still re4uired today

on a direct6injection petrol engine. "nd it does not re4uire sulfur6free fuel li'e a direct6injection petrol

engine, achieving its superior fuel economy with proven l B1 technology, which allows the @alvetronic

engine to run on all commercially available grades of regular petrol. n other words, the customer

enjoys all the consumption6related advantages of @alvetronic also when driving in countries without a

nationwide supply of sulfur6free fuel. The consumption figures for the 1Dti nevertheless relate to the

use of premium fuel with an octane rating of E IO*. Together with its D6liter $1.E mp gal% fuel

tan', the 1Dti offers a much longer range than its predecessor, with e)tra6urban fuel consumption in

the !uropean ! test cycle of just . liters for 100 'ilometers $. mp gals%. This means that the

driver would only have to refuel after a very significant 1,1(( 'ilometers or FF miles.

.%. Ot"er A-vanta(e#

"nti6'noc' control for running on all fuel grades between (F and EE octane.

#aintenance6free ignition system with individual coils.

#aintenance6free valve drive with hydraulic valve play compensation.

" -ervice nterval ndicator to 'eep the cost of service to a minimum

" two6mass flywheel for ma)imum running smoothness

@alve drive with roller bearings throughout in the interest of minimum friction and fuel

consumption.

"dvanced catalysts near the engine in special manifold design for minimum emissions.

n @alvetronic engines coolant flows across the head, resulting in a temperature reduction of

D0.

The water pump si8e is cut in half, reducing power consumption by D0.



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The power steering fluid is warmed 4uic'ly, reducing the power used by the hydraulic pump.

#ounting the water and power pump on the same shaft and a heat e)changer between

coolant and engine oil reduces oil temperature by 0.

>#? has successfully completed this 4uantum leap in technology, even in the light of a

demanding product development process. "n important tas' in this process is to reduce the product

development period to just 0 months. This applies to all new products. " further objective is to

reduce the amount of hardware re4uired and provide a broad 'nowledge base for the new @alvetronic

technology, the 'now6how ac4uired in this process serving to develop this technology to an even

higher standard with new functions. Computer aided e)ercise $C")%6based methods and three6

dimensional calculations were applied consistently in this project, ensuring successful application of

the new technology in the car despite the high level of product comple)ity. This new mechatronic

system calls for multi6parameter load management re4uiring the introduction of new control

algorithms and new, even more efficient, engine management.

.'. Di#a-vanta(e#

9acing such a high standard of software and hardware comple)ity, a manufacturer obviously

also runs a greater ris' of ma'ing mista'es. t is essential to ac4uire a sufficient stoc' of data under

all 'inds of operating conditions in order to understand how such a new system behaves. owever,

such data cannot be provided by the usual se4uential test runs.

"ll6round, general use of the latest direct6injection technology, in turn, faces some significant

drawbac's such as costs, the need to ma'e the combustion process very robust and the potentials in

e)haust emissions treatment.

3. E4ERI5ENTAL RE0ULT0

3.1. +ir#t !or,in( 5o-el

The first >#? model to enter the mar'et in 2001 with a large6production spar'6ignition

engine featuring fully variable @alvetronic and @anos valve control was the 1Dti Compact. n turn,

the first representative of this newly developed family of engines was a four6cylinder four6valve spar'6

ignition power unit displacing 1.( litres, developing ma)imum tor4ue of 1F *ewton meters $*m% and

ma)imum output of ('? $see Figure 4%. >#?s new @alvetronic four6cylinder power units come with

1.(6litre and 2.06litre capacities.

3.2. 0o/e E6&eri/ental re#ult#

5espite the reduction in engine si8e by 100 cubic centimeters, compared with the former

generation of power units, tor4ue is up from 1D*m to 1F*m, with output increasing from FF'? to

('?. ?ith displacement of the 2.06litre engine being increased by , tor4ue was up by no less

than 11 from 1(0*m to 200*m, engine output increasing from (F'? to 10'?, resulting in specific

tor4ue of 100*m/litre and specific output of 2.'?/litre.

The driver senses this enhanced performance through the more powerful tor4ue curve, the

cars dynamic behaviour on the road clearly proving the advantages of this e)tra tor4ue. #ore than

E0 of the engines tor4ue comes at just 2,000 revolutions per minute $rpm%, with tor4ue pea'ing at

,F0rpm. !ngine output, in turn, remains consistently at its near6ma)imum throughout a wide speed

range.

The &.&6litre power unit develops a ma)imum output of 2&'? with a fuel consumption of

only 10.E litres/100'm $or 2.E miles per gallon% and already complies with the !& standard, which



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does not become obligatory until 200. The oil service intervals, in turn, have been e)tended up to

&0,000'm or 2,000 miles.

One of the most important objectives from the start was to reduce fuel consumption. These

engines offer a particular enhancement of fuel economy above all at low loads. ?hen idling, fuel

consumption is down by appro)imately 2 and the overall improvement in the !uropean fuel

consumption test cycle is 12. The customer will also e)perience this improved economy and fuel

efficiency in everyday motoring on the road. sing the power of the engine in full, on the other hand,

the driver does not have greater fuel efficiency than with a conventional power unit. The reason for

this is that, under these conditions, the engine runs li'e a throttle butterfly power unit with its

butterfly fully open. nder normal driving conditions, however, throttle6free load management

significantly reduces fuel consumption in practice.

7. CONCLU0ION

n summary, these innovative developments provide a combination of product features thus

far inconceivable with a spar'6ignition engine. The introduction of the worlds first inta'e manifold

providing infinite variation in manifold length serves to improve the tor4ue level, which is already very

good to begin with. " particular highlight of engines with @alvetronic load management is the

significantly improved fuel/air mi)ture guaranteeing minimum fuel consumption, ma)imum

spontaneity and optimum refinement.

59 with a stochiometric air/fuel ratio provides the highest level of specific output as well as a

combustion process helping to fulfil all e)haust emissions standards worldwide. "ll6round, general use

of the latest direct6injection technology, in turn, faces some significant drawbac's such as costs, the

need to ma'e the combustion process very robust and the potentials in e)haust emissions treatment.

@alvetronic combines a significant improvement of fuel consumption with e)cellent engine

response and control, allowing optimum valve timing under all running conditions. The result is

smooth and free operation of the engine under part load with very little throttle effect. Optimised

fuel/air mi)ture management ensures significant advantages in fuel efficiency compared with aconventional four6cylinder engine, reaching the same standard as todays lean6burn concepts. -ince

such an engine with @alvetronic does not re4uire an *O) removal catalyst, it can be used worldwide

with all types and grades of fuel.

8. RE+ERENCE0

www.bmwworld.com/technology/valvetronic

www.bmwworld.com/engines/valvetronic

www.wi'ipedia.org/wi'i/valvetronic

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25072013082800 valvetronic engine

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