publisher: luk gmbh & co. - schaeffler.com€¦ · publisher: luk gmbh & co....

Publisher: LuK GmbH & Co.Industriestrasse 3 • D -77815 Bühl/Baden

Telephon +49 (0) 7223 / 941 - 0 • Fax +49 (0) 7223 / 2 69 50Internet: www.LuK.de

Editorial: Ralf Stopp, Christa Siefert

Layout: Vera WestermannLayout support: Heike Pinther

Print: Konkordia GmbH, BühlDas Medienunternehmen

Printed in Germany

Reprint, also in extracts, withoutauthorisation of the publisher forbidden.

Foreword

Innovations are shaping ourfuture. Experts predict that therewill be more changes in the fieldsof transmission, electronics andsafety of vehicles over the next15 years than there have beenthroughout the past 50 years. Thisdrive for innovation is continuallyproviding manufacturers and sup-pliers with new challenges and isset to significantly alter our worldof mobility.

LuK is embracing these challen-ges. With a wealth of vision andengineering performance, ourengineers are once again provingtheir innovative power.

This volume comprises papersfrom the 7th LuK Symposium andillustrates our view of technicaldevelopments.

We look forward to some intere-sting discussions with you.

Bühl, in April 2002

Helmut Beier

Presidentof the LuK Group

Content

LuK SYMPOSIUM 2002

1 DMFW – Nothing New? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Torque Converter Evolution at LuK . . . . . . . . . . . . . . . . . . . . . . . 15

3 Clutch Release Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4 Internal Crankshaft Damper (ICD). . . . . . . . . . . . . . . . . . . . . . . . . 41

5 Latest Results in the CVT Development. . . . . . . . . . . . . . . . . . . . 51

6 Efficiency-Optimised CVT Clamping System . . . . . . . . . . . . . . . 61

7 500 Nm CVT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

8 The Crank-CVT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

9 Demand Based Controllable Pumps. . . . . . . . . . . . . . . . . . . . . . . 99

10 Temperature-controlled Lubricating Oil Pumps Save Fuel . . . 113

11 CO2 Compressors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

12 Components and Assemblies for Transmission Shift Systems135

13 The XSG Family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

14 New Opportunities for the Clutch?. . . . . . . . . . . . . . . . . . . . . . . 161

15 Electro-Mechanical Actuators. . . . . . . . . . . . . . . . . . . . . . . . . . . 173

16 Think Systems - Software by LuK. . . . . . . . . . . . . . . . . . . . . . . . 185

17 The Parallel Shift Gearbox PSG . . . . . . . . . . . . . . . . . . . . . . . . . 197

18 Small Starter Generator – Big Impact . . . . . . . . . . . . . . . . . . . . . 211

19 Code Generation for Manufacturing. . . . . . . . . . . . . . . . . . . . . . 225

WESTEV

17 The Parallel Shift Gearbox PSG . . . . . . . . . . . . . . . . . . . . . . . . . 197

197LuK SYMPOSIUM 2002

The Parallel Shift Gearbox PSGTwin Clutch Gearbox with Dry Clutches

Reinhard BergerRolf MeinhardCarsten Bünder

17

17 The Parallel Shift Gearbox PSG

198 LuK SYMPOSIUM 2002

IntroductionThe Parallel Shift Gearbox (PSG) is a variantof the twin clutch gearbox.

Such gearboxes have been around for a longtime. For example, at the end of the 1980s aPorsche twin clutch gearbox (PDK) was beingused in motor racing [1]. However, it neverreached production. Thanks to the search fortransmission systems which minimise fuelconsumption, twin clutch gearboxes are nowexperiencing a renaissance.

Fig. 1: PSG - Principle

As a member of the XSG family [2] the PSGhas the following features:

� Dry clutches and electro-mechanical clutchactuators,

� Parallel shaft design and constant meshgears

� synchronised dog clutches with electro-me-chanical actuator and Active Interlock [4],

� system strategy elements in common withthe ASG.

It is this combination of features thatmakes the PSG stand out from other twinclutch gearboxes.

In terms of functionality and comfort, therequirements of a PSG and its compo-nents correspond to those also placed onthe automatic transmission designs of to-day.

The logical integration of the PSG in theXSG family is therefore particularly im-portant, since a whole string of gearboxmanufacturers are working on modulargearbox families, where, in addition to themanual gearbox, various automated ver-sions are also produced using the samemanufacturing equipment. LuK extendsthis modular approach to its components,clutches and actuators. Hence, for exam-ple, the same gear actuator can be usedfor an ASG or a PSG in conjunction withthe Active Interlock.

This paper shows the opportunities avail-able if dry clutches are used in a twinclutch gearbox, but also highlights the is-sues still to be resolved. It further dem-onstrates the integration of the individualcomponents presented in other papers[2], [3], [4], [5] into the entire system. Thesubject of vibration isolation using slipcontrol also plays an important part here.



Opportunities and Key Issues for the Dry Clutch in the PSG

OverviewLuK manufactures about 12 million dry clutch-es and about 3 million lock-up clutches fortorque converters annually. Hence it possess-es a wealth of know-how of both variants – dryand wet. This also applies to automation,since, in addition to ASG applications with dryclutches, LuK also played quite a crucial partin the development of the wet starting clutchfor Audi’s multitronic®.

The following explains why the use of a drytwin clutch is preferred in the PSG:

� Lower fuel consumption,

� Option for modular gearbox families (MT,ASG, PSG),

� More frequently used as start-up element.

This has raised various concerns which cropup repeatedly whenever there is talk of replac-ing conventional automatic transmissionswith gearboxes with dry clutches. More spe-cifically, these are:

� Lining wear,

� Thermal capacity and robustness againstmisuse

� Controllability,

� Behaviour in the event of a system failure.

LuK will today demonstrate that all these is-sues can be satisfactorily resolved. In somecases, there are even advantages of using thedry clutch in comparison to the wet clutch -seefigure 2. The most important criteria are nowcovered in detail.

Fig. 2: Dry or Wet Clutch

Gearbox Power Loss and Fuel Consumption

With more than 96%, the manual gearbox(MT) has an outstanding full-load efficiency.However, in actual driving cycles with a highpart-load content, friction losses in gears andbearings as well as lubrication losses, have al-ready reached double figures [6]. Figure 3 il-lustrates the additional losses that occur in theclutches and for the gearbox control (whilst thebase loss figures mentioned above are con-sidered equal across all variants and conse-quently not shown).

These values describe the rates of power lossin relation to the energy induced in the com-bustion engine. Convertion into consumptionvalues can result in slight discrepancies due tothe engine consumption mapping.

dry clutch wet clutch

consumption

overload capacity hill take-up

option for modular families

packing space/weight

fail safe behaviour

shift qualitycontrollability



Fig. 3: Clutch Losses and ControlAuxiliary Energy

Friction losses occur in the clutches whenstarting up and changing gear. This only af-fects the gear shifts for automatic transmis-sions, since start up is via the torque converterand not the clutches (start-up energy AT is in-cluded in the orange bar). As a result of thepower shifts on the PSG and wet twin clutchgearbox (hereafter, ‘DKG’), the clutch lossesprove to be approximately 0.6% higher com-pared with the manual gearbox in the NEDCcycle.

Further losses occur as a result of drag torquein the non-active clutches. This represents adistinct advantage for the dry clutch. The larg-est slip losses occur in the automatic trans-mission (AT) of conventional design, sincethree or more load-free clutches or brakes withseveral discs are dragged along constantly[7]. On the PSG and wet DKG the load-freeclutch runs without drag losses during driving,if no gear is preselected.

A dry clutch system with an electro-mechan-ical actuator is also the optimum solution whenauxiliary power is required for the actuation ofclutches and gear shifting. The average elec-trical power requirement is estimated at20 watts; on the current ASG in production itis 12 watts. The oil pump, which runs perma-nently, the leakage of pressurised oil, the oilflow through the radiator and the filter all causeconsiderably greater losses on the AT or wetDKG. Since there is a constant engagement

downforce on the clutch(es) during driving, anelectrical oil pump would not improve the sit-uation.

Given the automotive industry‘s voluntarycommitment to reduce fleet consumption by2008 to 140 g CO2 per kilometre, the alterna-tive concept with the dry clutches is the bestpossible solution.

Service Life of Dry ClutchesSince the introduction of asbestos-free clutchlinings and self-adjusting clutches with in-creased wear life, the replacement of theclutch within the normal life of a car is practi-cally never wear-related. With an automatedclutch the average service life is even furtherincreased. This is not only due to the greaterconsistency in clutch actuation, but also to thestrategies implemented against misuse.

In contrast to that, one question is justifiablyraised regarding the PSG: how does a dryclutch sustain the additional energy input fol-lowing the power shifts? After all, a clutch mustfirstly take over the full engine torque and thenreduce the speed difference. This createsthree times more fictional energy than in ASGgearshifts.

A mixed driving cycle has been developed atLuK to estimate the service life of dry clutches,which has gained approval from our custom-ers with field results and endurance tests. Thiscycle contains 50% urban driving, 30% ruraldriving, 18% motorway driving and 2% hilldriving. In total, this cycle includes 240 000journeys and 1.5 million gear shifts at a re-quired vehicle endurance of 240 000 km.

Figure 4 shows the results of the wear extrap-olation for a standard-size vehicle. It is clearfrom the figure that part of the start-up energyis also absorbed in the clutch of the secondgear. Depending on the ratio configuration, itis possible on the one hand to start up directlyin second gear (e.g. part-load operation) or toapply both clutches during start-up.

The results shown in figure 4 are based on anaverage wear rate that is 30% higher than to-



day‘s manual gearbox. This is in order to takeaccount of the properties of future lead-freelinings and also to take into consideration thehigher temperature of the component (higherenergy input due to power shift).

Fig. 4: Service Life of Dry Twin Clutch

Situations with a Very High Energy Input

Constant creeping, crawling, hill starts withand without a trailer, hillholding vehicle – mostof the concerns in these situations are linkedwith the use of a dry clutch in an automatictransmission. Every vehicle manufacturer hashis own tests for this, which, to some extent,focus on very different things.

By automating the dry clutch, situations witha very high energy input are better controlledthan with a manual gearbox. This is reflectedin the experiences with the Mercedes A-Class(ECM) and the Opel Corsa (ASG). The PSGagain offers even more potential than an ASG,more specifically, for the following reasons:

� A gearbox that is 100% fully automated of-fers more freedom in the ratio configurationof the first gear than an add-on ASG. A high-er ratio (first and possibly second gear)does not automatically lead to worse cycle

consumption, but drastically reduces fric-tional power during start-up or creeping.

� On the PSG the frictional heat can be distrib-uted over two clutches and their cast mass-es respectively.

Fig. 5: Stopping on a Hill – Temperature Simulation

Figure 5 compares temperature simulationsfor ‘stopping on a hill’ for different options.

It can be seen that the time for which a PSGvehicle can be held on a hill without destroyingthe clutch (Case 3), is almost twice as long aswith a manual gearbox (Case 1). This is im-portant, for example, in situations such as ex-iting a car park, when it is necessary to waiton a slope and give way to other vehicles.

From a certain point, however, the self-pro-tecting mechanisms of the automated clutchhave to intervene, even on the PSG [5]. Pos-sible solutions for that are shown in figure 6.

A decision is therefore required as to whetherthe driver depresses the accelerator and thusexplicitly expresses a desire to accelerate, orwhether he merely lets go of the brake pedaland a small creeping torque builds up in theclutch. In the first case the clutch could begradually engaged after some time (a few sec-onds, see figure 5), in the other case the clutchwould have to open, see figure 6. During con-tinuous creeping however, the period prior tothe intervention of self-protection lasts severalminutes due to the low torque.



Fig. 6: Hillholding – Possible Clutch Protection Strategies

Measurements of clutchself-protection strategiesare also shown in [5].These strategies havebeen reviewed very posi-tively in several prototypecars.

Nevertheless, even bettersolutions are envisagedfor the future, namelywhen the gearbox controlcan request hill holdingfrom an active braking system.

Limp-Home BehaviourThis section looks at the limp-home behaviourduring a total failure of the gearbox control.From a gearbox control point of view, this iscertainly the most serious scenario. Just aswith every partial failure, it is essential that itshould never reach a safety-critical condition,i.e. there is a direct risk of accident and dangerto life and limb.

As the response to processor errors shows [5],it also applies here that maintaining the cur-rent status of both clutches at the moment ofthe failure is the best possible direct response,i.e. the clutches should neither open norclose, see figure 7.

With such limp-home behaviour, the risk of anaccident at red traffic lights or on a pedestriancrossing, for example, can be avoided, be-cause the clutches in these situations areopen and remain open. Even when driving thislimp home behaviour would take account ofthe current driver command and thus avoiddangerous situations, because the clutchescan not disengage suddenly. For example,this is important during close overtaking or hilldriving. On the PSG the driver of the vehiclecould still accelerate, if the complete failure ofthe gearbox control occurred during an over-lapping gear shift.

Fig. 7: Safe Condition during Total Failure

Dry clutches and self-locking electro-motori-cal actuators demonstrate such behaviour af-ter the power output stages are switched off.On the other hand, additional mechanical ef-fort would have to be used on wet clutches tofreeze the condition of the clutches.

If the customer requested, LuK could also of-fer a system with opening clutches as the fail-ure mode. An electromotorical actuator, hy-drostatic release system incorporating a valve



which opened in case of failure, together withnormally open clutches, would give such asystem.

If gearbox control and actuation fail in the mid-dle of an overlapping gear shift, the questionis raised as to whether this could lead to thegearbox locking. After all, a gear is engagedin each section and both clutches are trans-ferring torque. It must firstly be stressed herethat both clutches in total only transfer the en-gine torque, i.e. a clutch is simultaneouslyclosed and the other opened during an over-lapping gear shift. Thanks to the known adap-tations for the clutch characteristic curve(touchpoint, gradient) [9] and due to the torquetracking or slip control, this can be very pre-cisely adjusted.

In the event of limp-home operation, a clutchwould now quite simply slip, but the gearboxwouldn’t lock at all. The output torque can becalculated using the following formula:

MabOutput torque

MmotEngine torque

MK2Torque of slipping clutch

nmotEngine speed

n2Speed – input shaft with slipping clutch

i1Ratio of gear with sticking clutch

i2Ratio of gear with slipping clutch

This equation shows that the output torque isdetermined by the engine torque, the torqueof the slipping clutch and the gear step. Evenduring a failure of gearbox control the drivercan still influence acceleration with the en-gine. Figure 8 shows the power fluxes for thescenario where the driver wants to acceleratefurther.

Only if the driver takes his foot off the accel-erator would the deceleration be slightly high-er than expected, figure 9.

The danger of the wheels losing their grip hereonly exists if everything occurs together (fail-ure of both clutch actuators during an over-lapping and driver taking his foot off the ac-celerator) on a smooth surface. With suchroad conditions, however, a power on/off loadcondition can lead to the wheels slipping onany gearbox system, ever without an error ex-isting.

Fig. 8: Power Flows during Acceleration after

Gearbox Control Failure during Overlapping

Fig. 9: Power Flows when Coasting after Gear-

box Control Failure during Overlapping

This is clear from figure 10. In the accelerationtime curves the largest deceleration occurs af-ter the power on/off load condition in first gear.The deceleration of a PSG is only greater inthe steady-state, if the gearbox has failed andthe clutches were previously frozen during agear shift.

An engine drag torque-control can prevent thewheels slipping in both cases. Figure 10shows an example of this for a power on/offload condition on which the engine goes tozero torque.



Fig. 10: Power On/Off Load Condition:Acceleration Time Curves

The reliability of gearbox control of a PSGcompared with an ASG can be increased withmarginal additional vehicle wiring.

Fig. 11: Redundant Protection of the PSG-Gearbox Control

The individual clutch actuators are protect-ed separately, so that during a short circuitin a clutch actuator, for example, the gear-box control and the other clutch actuator arestill supported, figure 11.

The likelihood the failure scenario previous-ly considered, occuring (i.e. that both clutch-es transfer torque and can no longer bemodulated) is thus minimised and, in fact,requires a double failure to occur at all.

Controllability

A torque travel characteristic curve appliesto the controllability of a dry clutch. On a wetclutch, a combination of torque-volume-characteristic curve and torque-pressure-characteristic curve describes the transferbehaviour, figure 12. This combination re-sults from the fact that the wet clutch mustfirstly be pre-filled before an engagementforce can be adjusted via the pressure.

Dry and wet clutches have one thing in com-mon: the clutch torque transferred dependsquite considerably on the current friction co-efficient and can effect both systems. Thechanges in friction co-efficient of both sys-tems show the following peculiarities:

� The friction co-efficient of a dry clutchcan change more drastically than on thewet clutch, but can however be success-fully compensated for with intelligent ad-aptational algorithms [9].

� The dry clutch usually recovers over theservice life, even if it has drastically al-tered its characteristic curve temporarilyafter a high input of energy. With a wetclutch it leads to irreversible oil ageing,which is expressed by a negative frictionco-efficient gradient, figure 13. The orig-inal friction co-efficient characteristicscan be restored by changing the oil.



These statements are backed up by experi-ence with the ASG. For example, a pro-gramme exists at LuK for objectively evaluat-ing shift quality using measured accelerationcharacteristic curves. This is used for the reg-ular assessment of vehicles in an endurancetest. The results illustrated in figure 14 showthat the shift quality of an ASG with a dry clutchscarcely changes over the service life.

Fig. 12: Characteristic Curves

Fig. 13: Wet Clutch: Oil Ageing

Fig. 14: Dry Clutch: Constancy throughoutService Life

Design Examples

Dry Twin Clutch and ActuationHaving dealt with the functional aspects of us-ing a dry clutch in the PSG, design layouts arenow considered. The twin clutch, flywheel,clutch release systems and clutch actuatorsmust be configured in the assembly so that op-timum use is made of the limited packagingspace. All components should be located inthe clutch bell housing or on the gearbox. Thisresults in two particular challenges:

� The axial packaging space in the clutch bellhousing (especially on transverse applica-tions),

� the package around the gearbox for thoseactuator components which are not locatedin the clutch bell housing.

Figure 15 shows a twin clutch with DMFW onthe left; on the right is a twin clutch with damperclutch discs and a flex plate. The latter varianthas considerable advantages for an axialpackaging space (about 20 mm) and inertia(about 0.1 kgm²). The following section showshow it should not result in any disadvantageswith respect to vibrational isolation.



Fig. 15: Twin Clutch Design Examples

Various options for the release system andclutch actuator are the subject of [3] and [4].The design examples in figure 15 contain adouble ramp mechanism.

Figure 16 shows a design example for electro-mechanical actuators which actuate this dou-ble ramp mechanism.

The cover mounted connection of the releasesystem on the clutch via a support bearingshould also be emphasised. This has the fol-lowing advantages:

Fig. 16: Release System Twin Clutch

� Reduction of the tolerances to be consid-ered in the release system,

� radial support of the clutch mass in the gear-box housing,

� actuating forces do not affect the crankshaft,but are supported internally.

The clutch and release system form a unit andbelong to the gearbox. Hence the entire as-sembly and the self calibration of the completePSG can be done in the gearbox plant.

Continuous Slip for Vibration IsolationThe usual low noise comfort factor from theDMFW in the vehicle can also be achievedwith the more favourable, compact twin clutchvariant with damper discs and flex plate. Forthis reason, the clutch in the vibration-sensi-tive operating ranges of the closed transmis-sion system is operated with continuous slip.Information about the control strategy is pre-sented in [5].

The torsional vibration dampers in the clutchdiscs guarantee that driving without slip inwide speed ranges is possible [8].

In the operating ranges in which there arenoise problems with a closed transmission



system, the specific slip offers partially betterisolation than a DMFW.

With power on/off load conditions, both fromtip-in to back out and vice-versa, vibration ex-citations in the transmission system can beavoided by using slip control [9].

From the dynamics point of view, the variantwithout DMFW offers equal advantages. Allthings considered, the inertia of the twin clutchis approximately as great as the entire inertiaof a DMFW and a single clutch, i.e. in termsof the inertia there is scarcely any differencebetween the manual transmission or ASG andthe PSG. Hence the accelerating performanceand the engine dynamics are comparable. Ona twin clutch with DMFW, the primary mass,which is necessary for stabilising the crank-shaft, would still have to be added as an ad-ditional inertia. This lies within a range of0.1 to 0.13 kgm2, see figure 17.

Fig. 17: Inertia Torques (inc. Crankshaft)

The primary flywheel of the combustion en-gine on the solution with the flex plate is con-siderably greater than on the DMFW solution,hence the crankshaft runs more quietly any-how. This means that the excitations on theengine side are reduced on a PSG with drytwin clutch, flex plate and damper clutch discs,compared with the other gearbox variants,also when compared with a manual transmis-sion, see figure 18.

Simulation calculations and tests have shownthat continuous slip in certain ranges for vi-brational isolation does not lead to increasedfuel consumption and only causes slight extrawear of the clutch linings.

Fig. 18: Rotational Irregularities

At first sight, it may seem implausible that ad-ditional clutch slip does not increase fuel con-sumption. This is due to the lower inertia of theunit compared with the DMFW solution. Theadditional primary inertia of the DMFW mustalso be accelerated in all acceleration opera-tions, so that non-usable kinetic energy isstored in it. With a primary mass of 0.1 kgm2,it corresponds to additional consumption ofabout 0.5% in NEDC cycle. Losses were cal-culated in the same magnitude for continuousslip in certain ranges, hence the saving due tolower inertia and the loss due to slip compen-sate each other, see figure 19.

Fig. 19: Consumption Results PSG with/without Slip Control

The slight extra wear of up to 0.4 mm perclutch was previously shown in figure 4.

without DMFW with DMFW

MT / ASG 0,2 kgm2 0,25 kgm2

PSG 0,25 kgm2 0,35 kgm2

increased consumption

manual mode

automatic mode

optimised engine operating point ± 0% -5,0%

reduction of inertia -0,5% -0,5%

slip control +0,5% +1,0%

total ± 0% -4,5%

*typical average value



Active Interlock for Gearbox Actuation With the Active Interlock system [4] developedby LuK, the effort for automated shift actuationin the gearbox is reduced to a minimum. Thecomponents of the internal shift mechanism(shift forks, shift rails, guide parts) correspondto that of a manual transmission or ASG,figure 20. No additional gear actuator is re-quired for the second section of the PSG(figure 1). It is only neccessary to modify theASG gear actuator locking elements in orderto be able to use it for shifting both PSG sec-tions.

Fig. 20: Active Interlock Shift System for PSG

For gearbox manufacturers who derive thePSG modularly from a manual transmissionfamily, the Active Interlock shift system is par-ticularly advantageous due to its great simi-larity to the manual shift mechanism/ASG.Even the flange for the installation of the gearactuator can be designed exactly like theflange for the shift mechanism on the manualtransmission module [4].

It is possible to do without the second actuatorif the shift slot in the shiftrails is wider than theshift finger which operates the shift rails viathis shift slot. Hence two gears can be simul-

taneously engaged in the PSG, i.e. an evenand odd gear at the same time see figure 21.

The Active Interlock system also ensures thatneither two odd, nor two even, gears can everbe engaged simultaneously [4].

Fig. 21: Shifting Two Gears with Active Interlock

Integration of Parking LockThe PSG should not only be a fully adequatereplacement for today’s automatic transmis-sion from the functionality point of view, butalso in terms of operability. This now leads tothe demand for an integrated parking lock. Inthe future this function can probably beachieved with electrical braking systems.

In current projects, LuK has investigated thepossibilities of not only using the advantagesof the shift-by-wire system (noise decoupling



Fig. 22: Example of Design with Integrated Parking Lock

to the vehicle interior, freedom for in-terior design), but also developingparking lock solutions with minimumadditional effort, without resortingback to the braking system.

The most simple solution appears to beto engage a gear in each section of thegearbox and close both clutches. How-ever, the starting of the combustion en-gine with the selector lever in P positionin this condition would not be possi-ble, because the clutches wouldhave to be open and hence the parklock lifted. This would contradict thestate-of-the-art in terms of automatictransmissions with a parking lock.

As can be seen from today’s automatictransmissions, the mechanical parkinglock ratchet is a relatively simple com-ponent. The parking lock ratchetcould also be operated by the elec-tro-mechanical gear actuator of thePSG. This suggests the followingideas:

� The parking lock ratchet is activelyengaged and disengaged throughthe gear actuator.

� The engagement of the parkinglock ratchet is via a spring-type ac-tuator, whilst the release is activelydone by the gear actuator. Duringdriving the parking lock is held openby a retaining magnet.

Both solutions are practical accordingto current state of the art technology.At the end of the day, the design mustbe adjusted in collaboration with thevehicle manufacturer to the preferredoperating concept. LuK’s concern isto save it’s customers extra effort byconsidering the option of the parkinglock operation when designing thegear actuator.

Figure 22 shows an example of a de-sign for releasing the parking lock withthe electro-mechanical gear actuator.



Summary and OutlookThe Parallel Shift Gearbox is an automatictransmission with a dry twin clutch. It is partof the XSG family and builds on the know-howthat LuK has gained with the dry clutch and itsautomation, together with the automation ofmanual transmissions. The main argument forthe application of dry clutches is the greatestpossible fuel saving, without simultaneouslyhaving to tolerate loss in driving comfort com-pared with conventional automatic transmis-sion systems.

A first PSG functional sample is currently be-ing built at LuK. Further exciting projects areplanned with different vehicle and gearboxmanufacturers. As it stands, the first series ap-plication is envisaged for model year 2006.

Whilst the ASG is more suitable for smaller orsporty vehicles and engines, the PSG can beused in all vehicle classes and engines.

With its know-how and its components, LuKhopes to contribute to this by offering the cus-tomer innovative, economic and competitivetransmission systems.

References[1] Flegl, H.; Wüst, R.; Stelter, N.

Szodfridt, I.: Das Porsche-Doppelkup-plungs-(PDK)-Getriebe,ATZ 89 (1987) 9, p. 439 - 452.

[2] Fischer, R.; Schneider, G.: The XSGFamily – Dry Clutches and Electric Mo-tors as Core Elements of the Future Au-tomated Gearbox, 7th LuK Symposium2002.

[3] Reik, W.; Kimmig, K.-L.; Meinhard, R.;Elison, H.-D.; Raber, C.: New Opportu-nities for the Clutch? 7th LuK Symposium2002.

[4] Pollak, B.; Kneissler, M.; Esly, N.;Norum, V.; Hirt, G.: Electro-MechanicalActuators – Setting Gearboxes in Motion,7th LuK Symposium 2002.

[5] Küpper, K.; Werner, O.; Seebacher, R.:Think Systems – Software by LuK. 7th

LuK Symposium 2002.

[6] Wagner, G.: Berechnung der Ver-lustleistung von Kfz-Vorgelegegetriebe,VDI Berichte 977, 1992, p. 175 - 198.

[7] Wagner, G.; Bucksch, M.; Scherer, H.:Das automatische Getriebe 6HP26 vonZF-Getriebesytem, konstruktiver Auf-bau und mechanische Bauteile, VDIBerichte 1610, 2001, p. 631 - 654.

[8] Fischer, R.; Berger, R.: Automation ofManual Transmissions, 6th LuK Sympo-sium 1998.

[9] Fischer, R.; Berger, R.; Salecker, M.:Anforderungen an die Verbrennungsmo-tor-Steuerung bei Automatisierung desSchaltgetriebes. 19. InternationalesWiener Motoren Symposium, Mai 1998.

publisher: luk gmbh & co. - schaeffler.com€¦ · publisher: luk gmbh & co....

Documents