Mission CO2 Reduction: the Future of the Manual Transmission: Schaeffler

56 57

Mission CO2 Reduction The future of the manual transmission N x D H I O E A S M I O u e n l O A N G A D F J G I O J E R U I N K O P J E W L S P N Z A D F T O I E O H O I O O A N G A D F J G I O J E R U I N K O P O A N G A D F J G I O J E R a N p D H I O E A S M I O u e n l O A N G A D F O I E R N G M D S A U K Z Q I N K J S L O G D W O I A D U I G I r z H I O G D N O I E R N G M D S A U K n m H I O G D N O I E R N G U O I E U G I A F E D O N G I U A m u H I O G D V N K F N K K R E W S P L O C Y Q D M F E F B S A T B G P D r D D L R a E F B A F V N K F N K R E W S P D L R n E F B A F V N K F N W F I E P I O C o m f o r t O P S D C V F E W C G M j B j B K R E W S P L O C Y Q D M F E F B S A T B G P D B D D L R B E z B A F V r K F N K R E W S P z L R B E o B A F V N K F N J V D O W R E Q R I u Z T R E W Q L K J H G F D G M D S D S B N D S A U K Z Q I N K J S L W O I E P JürgenN N b KrollA U A H I O G D N p I E R N G M D S A U K Z Q H I O G D N w I E R N G M D G G E E A Y W T R D e E S Y W A T P H C E Q A Y Z Y K F K F S A U K Z Q I N K J S L W O Q T V I E P MarkusN z R HausnerA U A H I r G D N O I q R N G M D S A U K Z Q H I O G D N O I y R N G M D T C R W F I J H L M l K N I J U H B Z G V T F C a K G E G E F E Q L O P N G S A Y B G D S W L Z U K RolandO G I SeebacherK C K P M N E S W L N C u W Z Y K F E Q L O P P M N E S W L N C t W Z Y K W P J J V D G L E T N O A D G J L Y C B M W R Z N a X J X J E C L Z E M S A C I T P M O S G R U C Z G Z M O Q O D N V U S G R V L G R m K G E C L Z E M D N V U S G R V L G R x K G K T D G G E T O I Z S W Q E T U O M B C Y N V X H N V u V u J R C N I F Z K M N D A B O N Y A M E C R J G N I N E E O M N Y A Z T E W N l X J R C N I F E E O M N Y A Z T E W N y X S R C T C R W U U M a I Z R W O U Z T W H N E D L D Q F Q F u a J K U V X E S Y M N R E E W C L O M E P S C V C Y L i N E W C L V V F H N V o a J K U V Y L i N E W C L V V F H N V K Y Q W P J K P S D v G H J K L P O I U Z T R E T E N A N A F H t G U P W Q V Z E S L N F A M U A N J Y Q Y O Y O B R n L N F X T J O L D Q F H B w n G O B R n L N F X T J O L D Q O E I a u t o m a t i o n D S A Y V N P I Z R W Z Y K F K F A O E C K t a C T S V Q D E F B N I M B L P O P Q P Q A Y C B E F V B N R T E N A O D F E C Q A Y C B E F V B N R T E N N U E S R C K O I J n R D C K I O P M N E S W L S A C V C V F E O P N G X E V S D K D L D W C Y Q B E B G B A B A Y X S W A D C B P L M I J N T B G H U A Y X S W A D C B P L M I J B H B K Y Q O G N T g D S Q O M G D N V U S G R R T C A C A V B E T Z H N D E u Z N U B J Z M H Z D H N B N U N U I O P L K U H G F D S A C V B O F E T U I O P L K U H G F D S A C N E T O E I N R L U E G D I N G R E X O M N Y A G S G E G E A S N R O A K L P m X W E W a g Q S W I E R T R Q R Q H G F D L G E N D E R T C A S N I N R Q H G F D L G E N D E R T C R S H N U E I N R L U J G D I N G R E X O M N Y N M Z G Z G E B Z Y L s I d a m x e r F F I M b C H S E H E B E B U P S K U P P L U N G S G E B E R Z Y B U P S K U P P L U N G S G E P I C O O V C E S O P M N V C S E Y L J N E W B V C X C X G O S E D C U J M a K O Q A C E C B S t P O I O D O D C V F E W C V T E B N M Z G O H A S E D C 4V F E W C V T E B N M Z O W R Y I Z Q Y A H I N C W Q Y J A O B R E L N E C R F R F X Y M O K N l o k t U Q T F D G V T Q U j x R E L E L K J H G F D S A M M B V C X Y M L M O L K J H G F D S A M M B V C E A Y J K V N J R A K D O B N J O R O I D F N G S N W A W A F V B Z H N E U H i Z G W R Y L M R T X A g Y W P W P H C E Q A Y W S X E E C R F V E G B Z P H C E Q A Y W S X E E C R W F I U D M B B D B D M G R e B D P B D L R B E N M I Q I Q A S C V F s A b s o r b e r C X V N H O U b I J B J B Z G V T F C R D X E S N W A S R E C V B Z G V T F C R D X E S N W J V D A A O E U A N D O N G I U A R N H I O G D L K H E H E Q W T O I J V S G n J P N E Z V T F L U J a D G Y G Y C B M W R Z I P S F H K T V N Z L M O Y C B M W R Z I P S F H K T G G E M O T M Q O G N T Z D S Q O M G D N V U S P O N C N C E S C B F G Z B C Y D G T R X D B P O R U T E T M T M B C Y N V X A D G J L K H E S Y S C B M B C Y N V X A D G J L K H T C R U D M T B D B H M G R I B D P B D L R B E C V B N B N C A I K n D L P Q d C E Z R D C S K U P O W R W Z W Z T W H N E D K U N W P O N C A L V I K Z T W H N E D K U N W P O N W P J F E I D R E Q R I U Z T R E W Q L K J H G Z N J I J I N M W u R T S A Y a G D S W E H K L P F L K J K O K O I U Z T R E W Q Y X C V B N M I Q W u O I U Z T R E W Q Y X C V B K T D C I M N S t R E C L P Q A C E Z R W D X A Z Y K F K F I M t R E C C I T m M O S G W D X A Y H A S g S V S V N P I Z R W Q S C G Z N J I M N S t R V N P I Z R W Q S C G Z N J S R C K O I J E R D C K I O P M N E S W L N G R V K G E G E F E O P N G M N D p B O i z L Z U K O G I K C K P K P M N E S W L N C X W Z Y K F E D i O P P M N E S W L N C X W Z Y K K Y Q O G N T U D S Q O M G D N V U S G R V E W N F X J X J E C E M S A S Y M e R E z W R U C Z G Z M q g O D O D N V U S G R V L G R V K G E C E Z E M D N V U S G R V L G R V K G O E I N R L U O G D I N G R E X O M N Y A Z T E W N F X F X J L I F Z K W Q V r E g L N q a t s l o k z I N E N E X O M N Y A Z T E W N F X J L R N I F E X O M N Y A Z T E W N F X N U E I N R L I J G D I N G R E X O M N Y A V V F H N V N V R D U V X E B O Y R X w N G C L O M E P S C V C Y C Y L J N E W C L V V F H N V R D J K U V Y L J N E W C L V V F H N V C O O V C E S K P M N V C S E Y L J N E W C T J O L k Q k Q F H F G U P I N K J S Y t O F A M U A N J Y Q Y O Y O B R E L N F X T J O L s Q F H B Q F G O B R E L N F X T J O L a Q Y I Z Q Y A H D N C W Q Y J A O B R E L N F D F M G O I O I Z P D R N Q L O C Y Q I M F K M N S R D O J N J O J O I D F N G K L D F M G O I Z P M F D R O a D F N G K L D F M G O I J K V N J R A n D O B N J O R O I D F N G K E R N G M g M g S A U K Z Q I N K o S U W i m p l I E P N N R A U A H I O G D N O I E R N G M t S A U K Z Q H I O G D N O I E R N G M k U D M B B D B H M G R e B D P B D L R B E F B A F V N K F N k R E W S P S A C I T P M O E F B S A T B G P D B D D L R B E F B A F V N K F N q R E W S P D L R B E F B A F V N K F N A A O E U A N D O N G I U A R N H I O G D N O I E R N G M D S A g K Z Q L O C Y Q D M F k a p I E P N N R A U A H I O G D N O I E R N G M D S A l K Z Q H I O G D N O I E R N G M D M O T M Q O G N T Z D S Q O M G D N V U S G R V L G R V K G E C L Z E M K N I J B H U Z S G R U C Z G Z M O Q O D N V U S G R V L G R V K G E C L Z E M D N V U S G R V L G R V K G U D M T B D B H M G R I B D P B D L R B E F B A F V N K F N K R E W S P H N U J M I K O E F B S A T B G P D B D D L R B E F B A F V N K F N K R E W S P D L R B E F B A F V N K F N F E I D R E Q R I U Z T R E W Q L K J H G F D S A M M B V C X Y M L M O F H K N U T E Q G F D G V T Q U o t R E L K J H G F D S A M M B V C X Y M L M O L K J H G F D S A M M B V C C I M N S t R E C L P Q A C E Z R W D X A Y H B M W R Z I R F V E G B Z I J E U H B Z G Q A Y L M R T X A z Y W P H C E Q A Y W S X E E C R F V E G B Z P H C E Q A Y W S X E E C R P J M N I J H L M O K N I J U H B Z G V T F C R D X E S N W A S R E C V F G M H T I L Q T F C X V N H O U b I J B Z G V T F C R D X E S N W A S R E C V B Z G V T F C R D X E S N W C G T J D G L E T U O A D G J L Y C B M W R Z I P S F H K T V N Z L M O n D V S G W J P W R Z V T F L U J r D G Y C B M W R Z I P S F H K T V N Z L M O Y C B M W R Z I P S F H K T J T Z U E T O I Z R W Q E T U O M B C Y N V X A D G J L K H E S Y S C B R T Z B C S D G N V X D B P O R U T E T M B C Y N V X A D G J L K H E S Y S C B M B C Y N V X A D G J L K H V W M O R W U U M P I Z R W O U Z T W H N E D K U N W P O N C A L V I K E C L P Q A C E N E D C S K U P O W R W Z T W H N E D K U N W P O N C A L V I K Z T W H N E D K U N W P O N A K D L J K P S D F G H J K L P O I U Z T R E W Q Y X C V B N M I Q W u R T Z B C S D G T R E H K L P F L K J K O I U Z T R E W Q Y X C V B N M I Q W u O I U Z T R E W Q Y X C V B L S J A D S Y K J H G F D S A Y V N P I Z R W Q S C G Z N J I M N S t R E C L P Q A C E Z R W D X A Y H A S e S V N P I Z R W Q S C G Z N J I M N S t R V N P I Z R W Q S C G Z N J E K J I C K O I J G R D C K I O P M N E S W L N C X W Z Y K F E D i O P N G S A Y B G D S W L Z U K O G I K C K P M N E S W L N C X W Z Y K F E D i O P P M N E S W L N C X W Z Y K L S J A D S Y K J H G F D S A Y V N P I Z R W Q S C G Z N J I M N S t R E C L P Q A C E Z R W D X A Y H A S u S V N P I Z R W Q S C G Z N J I M N S t R V N P I Z R W Q S C G Z N J E K J I C K O I J G R D C K I O P M N E S W L N C X W Z Y K F E D i O P N G S A Y B G D S W L Z U K O G I K C K P M N E S W L N C X W Z Y K F E D i O P P M N E S W L N C X W Z Y K M O T M Q O G N T Z D S Q O M G D N V U S G R V L G R V K G E C E Z E M S A C I T P M O S G R U C Z G Z M o x O D N V U S G R V L G R V K G E C E Z E M D N V U S G R V L G R V K G T N U G I N R L U J G D I N G R E X O M N Y A Z T E W N F X J L R N I F Z K M N D A B O B N x z p e w n q m I N E X O M N Y A Z T E W N F X J L R N I F E X O M N Y A Z T E W N F X D C O S V C E S O P M N V C S E Y L J N E W C L V V F H N V R D J K U V X E S Y M N R E i W C L O M E P S C V C Y L J N E W C L V V F H N V R D J K U V Y L J N E W C L V V F H N V M O T M Q O G N T Z D S Q O M G D N V U S G R V L G R V K G E C E Z E M S A C I T P M O S G R U C Z G Z M a x O D N V U S G R V L G R V K G E C E Z E M D N V U S G R V L G R V K G A A O R U A N D O N G I U A R N H I O G D N O I E R N G M D S A U K Z Q I N K J S L W O z w u I E P N N R A U A H I O G D N O I E R N G M D S A U K Z Q H I O G D N O I E R N G M D 58 Manual Gearbox 4 59

oped. Although the centrifugal pendulum ab- Introduction 30 sorber (CPA) developed by LuK also offers good potential for the coming years, in the long term, even more capable systems will 25 The internal combustion engine will continue need to be integrated. to be the dominating force behind individual mobility for some time to come. The biggest 20 challenge in this context, however, revolves around lowering fuel consumption in line with Initial situation – 15 ever more stringent legal requirements while Manual transmissions at the same time maintaining driving comfort and pleasure. All aspects of the engine and under pressure Production in millions 10 transmission must be revisited with equal at- tention, whereby driving strategies that mini- mize consumption are key to achieving des- 5 ignated performance targets. To improve on In addition to the effort expended to further these aspects, the transmission must be fur- reduce the consumption of the engine itself, 0 ther automated and coupled with electrifica- equal focus must be placed on developing a 2014 2020 2014 2020 2014 2020 2014 2020 2014 2020 2014 2020 tion measures. The conventional manual transmission that optimizes the efficiency of NAFTA Europe China India Japan ROW transmission is therefore coming under pres- the entire powertrain. The manual transmis- sure and runs the risk of being „overrun“ by sion is initially positioned quite well in this re- MT DCT AMT other designs at least in the developed mar- gard, since it offers a high level of operating AT CVT kets. On the other hand, manual transmis- efficiency. Additional, conventional improve- sions remain attractive for cost reasons and ment measures, such as reducing frictional Figure 1 Global vehicle production based on transmission technologies (source: CSM, Aug. 2013) may continue to play a key role in the future if loss and increasing the number of gears and a way is found to develop systems that also gear ratio spread, are limited in their potential, in several vehicle categories in order to com- New opportunities for the enable „sailing“ and other efficient drive however. The transmission can therefore only ply with tomorrow’s CO2 limits and avoid ex- modes to be achieved in vehicles equipped play a much more effective role if it enables pensive penalty payments. Vehicles currently manual transmission with a standard transmission. the internal combustion engine to operate un- permitted to expel 135 g/km will only be al- Adopting a partially automated setup for der conditions that allow it to burn as little fuel lowed to produce in Europe 130 g/km in 2015, the manual transmission would also open as possible. In terms of today’s engines, this and in 2020, this limit will drop to 95 g/km. the door to integrating comfort, conve- translates to low operating speeds or deacti- Against this backdrop, the manual Analyzing or assessing potential areas in which nience, and safety-oriented functions with- vation of the engine as soon as the driver’s transmission isn’t out of the game yet, as consumption can be reduced is best facilitated out additional cost. Fuel consumption could power requirement makes this possible. It you might think, since current estimates by conducting tests in line with the established then be further reduced by opting for longer goes without saying that a manual transmis- point in the opposite direction. The manual driving cycles to pinpoint in which phases cer- gear ratios, for example. Misuse, or abuse sion does not offer the ideal setup for tapping transmission still enjoys the highest share of tain measures can offer beneficial results. The of the clutch, causing it to overheat, can be this potential and is the reason why it is receiv- the market, especially in the entry vehicle stop rate of 20 % in the New European Driving reliably prevented thanks to the partially au- ing more and is increasingly under pressure. segments in the BRIC nations and in Eu- Cycle (NEDC), for instance, led to the wide- tomated setup. Apart from visual shift point recommendations, rope (Figure 1). spread implementation ofstart/stop systems in The end result – “extreme” downspeed- it is not possible to implement any other, more If this predominant market position is to be Europe, which can reduce overall fuel con- ing – has disadvantages, however, especially sophisticated, fuel-saving shift strategies. In ad- maintained in the future, the manual transmis- sumption in the range of 5 %. The logical en- when it comes to future engines, where few dition, hybrid and advanced start/stop functions sion will have to be upgraded. While emphasis hancement of this technology is to switch the cylinders and/or feature cylinder deactivation require a specific, baseline level of automation. needs to be placed on exploiting the potential engine off during normal driving, which in turn will be widely used. In order to realize the Viewed from this perspective, automation available for reducing fuel consumption, as- means that it has to be mechanically decou- comfort and convenience expected by end is no longer only driven by the needs and pects pertaining to convenience and comfort, pled from the rest of the powertrain. This is customers, ever better systems for isolating, wants of buyers looking for greater comfort such as launch or stop-and-go assist manag- what is known as “sailing” and theoretically is or dampening, vibrations, must be devel- and convenience, but is absolutely necessary ing traffic jams, cannot be overlooked. always a practical mode to be in when vehicle 60 Manual Gearbox 4 61

5.5 -6.1 % The sailing function for with automated or assisted launch proce- -2.6 % currently can only be dures, for example, and additional safety and 5.14 -6.1 % combined with an reassurance could be provided by incorporat- 5.00 automatic transmis- ing a strategy that prevents excessive heat to 5,0 4.87 4.83 4.86 4.85 4.85 sion and has already the clutch. 4.72 1997 2013 4.68 reached volume pro- Combining sailing with lower engine speeds 4.57 duction for several can theoretically reduce consumption by 5 to 4.5 models. The trans- 10 %, depending on the driving cycle. Integrat- mission itself does ing an automated clutch assembly would open Consumption in l/100 k m not need to be fully up even more possibilities (Figure 3).The higher 4.0 automated, howev- level of automation associated with this is per- NEDC WLTP er, and an automat- fect for setting the stage to transition to a hybrid- Figure 4 ECM at market launch (volume Basis Sailing (ICE on) Sailing G 4/5/6 (ICE off) production) and in a concept vehicle Start-stop Sailing (ICE off) ICE = Internal combustion engine ed clutch to discon- ized manual transmission. Coupled with an ad- nect the engine from ditional electric drive, such as an electric 48-volt Figure 2 Consumption benefits of start/stop systems and sailing across the transmission driven axle, it also would be possible to offer Automation of manual different driving cycles theoretically could functions like electric launch and creeping in a be sufficient enough. special stop-and-go mode. Driving at constant transmission – Old friends deceleration forces lie between those of driving Unlike vehicles with an automatic transmission, speeds could likewise take place without the resistance and engine braking torque. Current their manually shifted counterparts are required assistance of the internal combustion engine for the 21st Century NEDC do not incorporate these phases, which to hold a certain gear in a defined speed range (electric sailing), and during braking, the effec- is why the sailing function does not bring about under cycled testing. If an engine is to also op- tiveness of an energy recovery system could be any concrete benefits when comparing posted erate efficiently at low speeds, the gear ratios increased by the drag loss of the internal com- The electronic clutch management system fuel economy numbers. This will not be the provided must be adapted accordingly. The bustion engine. Internal calculations have shown (ECM, Figure 4) developed by LuK, which al- case when the WTLP (Worldwide Harmonized potential here should not be underestimated, that the total reduction in fuel consumption lows the driver to shift without having to en- Light Duty Test Procedure) takes effect, how- since a 10 % drop in engine speed reduces when all measures are combined can exceed gage the clutch, was launched in 1993 [2, 3]. ever. Internally conducted consumption simu- consumption by 7 % when traveling at a con- 20 % under cycled testing conditions [1]. What started out as a great idea did not win lations with a 2.0-liter diesel engine (Figure 2) stant 70 km/h in fifth gear (example simulation Increased comfort and convenience over end customers, however. Vehicles show that a reduction in fuel consumption of with a 2.0-liter diesel engine); under NEDC and represent an additional aspect that comple- equipped with an ECM were well received by more than 6 % is possible when a sailing strat- WLTP conditions, approximately 5.6 % and ments the lower levels of consumption. In only a few people and are no longer on the egy is incorporated. Even when sailing is only 2.5 % less fuel is consumed, respectively. an automated stop-and-go mode, the driver market. One of the reasons why acceptance used in higher gears (4/5/6), it is possible to re- Start-off performance would suffer somewhat, could take his left foot off of the clutch ped- was so low presumably has to do with the fact duce consumption by approximately 4 %. This however, as comfort levels decrease and al, making it much easier to drive in con- that when a vehicle comes only with an ac- is counteracted by the decreased benefits of clutch wear increases. An automated clutch gested traffic while at the same time mini- celerator and a brake pedal (i.e. no clutch modern start/stop systems under WLTP con- could provide the answer here, too, however, mizing wear and tear on the clutch. pedal), it very much resembles a vehicle with ditions, however, which perform more than by resolving this inherent conflict. The higher 50 % worse due to the lower stop rate. operative requirements could be compensated Clutch actuator

Enhancement of Assistance and Hybrid capability Protective functions start-stop, sailing comfort functions

Trans. actuator

MT ECM AMT

Figure 3 Motivation for clutch automation Figure 5 Automated manual transmission 62 Manual Gearbox 4 63

a conventional automatic transmission, and the aforementioned operative strategies for Spindle drive Position sensor Rotor the assumption is made that an ECM should reducing consumption. Stator LCU behave in this manner, which it cannot due to There are other ways to automate the its different design. manual transmission, however, without hav- The automated manual transmission ing to forego the clutch pedal. (AMT, Figure 5) also debuted in volume-pro- duced vehicles around this time and compet- ed directly with the ECM. Today, even this technology has not been able to win over cus- Clutch by wire – tomers and is currently offered on selected Intelligent clutch models only. This lack of acceptance can be attributed to the noticeable interruption in tractive power, which puts the AMT at an im- Piston mediate disadvantage to the automatic trans- One well-known concept is the clutch-by- mission when it comes to comfort. The global wire (CbW) design. For the driver, this trans- Cylinder Press. sensor market share for vehicles equipped with an mission very much resembles a convention- Pressure connection Angle sensor AMT is under 1 %, making this type of trans- al manual transmission because three mission by far the one with the lowest unit pedals are provided and there is no immedi- Figure 7 Hydrostatic clutch actuator – HCA quantities when viewed in the context of the ate sense of automation involved. Automa- other transmission technologies available. tion is, in fact, working “behind the scenes”, LuK has already presented the technology In this arrangement, the physical release force It therefore almost goes without saying since actuating the clutch pedal merely several times as a way to bring the manual of the clutch no longer acts on the pedal, that previous attempts to automate the serves to communicate the driver’s inten- transmission up to date, with design work which means that this must be emulated to manual transmission have been less than tion, which is detected by a position sensor. focusing on improving comfort levels with provide for a realistic experience. Schaeffler fruitful, as the unit did not impress drivers The clutch is actually operated by an actua- regard to using the clutch, accelerating from has addressed this need by developing a new enough in terms of enjoyment or comfort. tor assembly. As the name “by wire” no a stop, and improving NVH behavior. The product that appeals from a cost and installa- Today, however, new opportunities have doubt reveals, this system does not have a inherent problem with this approach, how- tion perspective. The result is a very compact presented themselves. The ECM and the hydraulic or mechanical connection that ever, was that the functions offered did not force emulator that replaces the conventional AMT both provide a solid basis to facilitate links the clutch with the clutch pedal. lead to a favorable cost-benefit ratio. The hydraulic master cylinder while mirroring its concept was then no longer pursued from dimensions (refer to [4] for details). Slave cylinder Reservoir the original design perspective and has The hydraulic clutch actuator (HCA, Figure 7), Clutch pedal never entered volume production. also developed by Schaeffler, can likewise be Master cylinder Figure 6 depicts the architecture of a fitted to actuate the clutch assembly and is clutch-by-wire system. The input data re- described in detail in [5]. This actuator tech- Electric motor quired by the clutch control unit comprises nology was designed specifically for hydrauli- LCU information about the vehicle (CAN) and the cally actuated clutches as found in automated Force driver’s intent (pedal position) as well as ad- transmissions and is now being used in vol- Spindle drive emulator ditional parameters such as transmission ume production double clutch transmissions. Clutch Actuator pos. speed, which are provided by on-board The inherent benefit of the HCA lies in its sensors. Predefined strategies then deter- universal adaptability. Not only can it be ac- Rpm sensor Pedal position mine the target clutch torque on this basis, commodated without having to make major and the system can correct driver inputs as modifications to the vehicle; it can also actuate required. For example, if the driver inadver- and control a CSC as well as a semi-hydraulic Vehicle signals (CAN) Control unit tently misuses the clutch or does not coor- slave cylinder. The latter may not represent the dinate it properly with the gas pedal which best configuration, however. The internal axial can cause the engine to stall, the system is stroke drives a hydrostatic system that, in turn, clever enough to override the driver’s com- produces an axial stroke on the release lever of Figure 6 Design and components of the clutch-by-wire (CbW) system mands. the clutch. It is therefore practical to actuate the 64 Manual Gearbox 4 65

Anti-judder control Torque SlipS control tracking Impulsep start Torqueuee Launch/ limitation modulationlaatioioon

Complexity Stall Torque demand protection Sailing Start-stop Requirements

Permanent Basic functions Temporary modulation Permanent modulation with (opening/closing) with low dynamics modulation high dynamics

Figure 8 Electromechanical actuator for CbW – Compact and performance oriented Figure 10 Actuator requirements versus functions release lever directly instead of indirectly, by that allows the same base actuator to be means of hydraulics. This has prompted used in all applications (Figure 9). This ac- MTplus – Partially Figure 10 provides a rough estimate or out- Schaeffler to develop a compact, perfor- tuator houses all electronics, including the line in this context by assessing several func- mance-oriented solution (Figure 8). The design sensors, electric motor, and a special spin- automated alternative tions based on dynamic performance and objective is to replace the semi-hydraulic cylin- dle drive for manual clutches (self-locking in application times as pertinent evaluation der with an electromechanical actuator without the closing direction). Depending on the criteria. The highest requirements relate to having to make substantial modifications to the constraints of the application, the base ac- functions for reducing vibrations. The re- transmission, since this makes it possible to tuator is mated to a mechanical or hydraulic The underlying idea is to arrange an actuator quirements for accelerating from a stop and add an automated clutch to an existing trans- module, which also serves as the connec- in parallel with the release system to consid- sailing are small by comparison as they do mission with minimal additional cost. tion point to the transmission. Development erably reduce the actuator performance or not require high dynamic response or ongo- In an effort to enhance flexibility still fur- and system costs are minimized as a result, capacity required. Consideration must also ing clutch modulation. ther, Schaeffler has taken an additional step which is absolutely required if these sys- be given to the functions that can still be ex- According to this estimation, a smaller by developing a modular actuator system tems are to be offered in conjunction with ecuted, however, and whether the remaining actuator would already offer sufficient po- price-sensitive manual transmissions. added value can justify an automated setup. tential for upgrading a manual transmission An additional description of this system Mechanical module and current developments in actuator technology as pursued by Schaeffler can be found in [6]. Elec. mot. The design requirements for the actua- LCU tor are comparably high with respect to the aforementioned possibilities for automating Spindle drive the manual transmission. The ECM and Base actuator CbW in particular require a pronounced dynamic response to also enable fast gear- shifts. If progress is made to considerably OR logic reduce these requirements, costs can be Hydraulic module lowered further. With this in mind, Schaeffler has taken a new direction whereby the Figure 9 Modular actuator concept for clutch is no longer operated by an actuator maximum flexibility every time. Figure 11 Basic concept of MTplus partial automation with OR logic 66 Manual Gearbox 4 67

Reservoir connection Position sensor Pressure in Figure 11 and has two defining character- Integrating the ac- Active secondary piston connection istics: 1) At no time when the actuator is actuator in the hydrau- Master cylinder connection Hydraulic cylinder tuated does this translate into the clutch lic pressure line, on pedal being moved and 2) the release posi- the other hand, is Piston rod tion of the clutch is well defined by OR logic. much more favor- This, in turn, ensures that the driver’s intent able with respect to is highly prioritized at all times. installation space The sketch provided in Figure 11 char- and adaptability. In acterizes an active master cylinder in prin- this setup, the ac- Electrical ciple, with a structural design shown in Fig- tuator unit is posi- Spindle drive connection Electric motor ure 12. The electric motor with spindle drive tioned where it can Electric motor Slave cylinder connection Spindle drive is arranged next to the master cylinder. The be physically ac- Clutch pedal Electrical connections linking the pedal and spindle commodated and is Figure 14 Alternative intermediate piston variant without additional loss connection connection drive to the piston rod allow only one force connected to the encountered during foot-operated actuation Figure 12 Example of an active master cylinder to be transmitted in the disengaging direc- hydraulic line. A di- (OR logic) tion, which correlates with the OR logic. rect transfer fom the design shown in System comparison – An active master cylinder has noticeable Figure 11 leads to an intermediate cylin- and make it possible to include the func- drawbacks, however, including a greater der with two pistons which divide the hy- Limitless possibilities tions mentioned above for reducing con- risk of noise being transmitted by the elec- draulic system (Figure 13). During auto- sumption. tric motor to the interior, additional installa- mated actuation, piston 2 is driven The challenge is to find a suitable actuation space required in the already cramped directly by the actuator, while piston 1 tor concept that allows a clutch to be actu- area surrounding the cylinder, and little to remains stationary. The previous sections discuss a number of ated conventionally and automatically. no universal adaptability. This type of actua- During manual, foot-operated actua- possibilities for automating the clutch used Steps must also be taken to ensure that the tor would have to be modified or redesigned tion, piston 1 drives piston 2 by way of the in a manual transmission. Figure 15 com- actuator does not interfere with foot-actuat- in many cases for different application sce- carrier ring, which in turn leads to two pares each of these variants side by side. ed operation and that the driver always has narios, which does not make it very attrac- drawbacks: 1) The seals produce addition- The most consequent variant is the ECM, complete control over the vehicle. tive from a cost standpoint. The same holds al friction and 2) the “sniffing” function re- which does away with the clutch pedal and Detailed concept studies were conduct- true for the majority of installation arrange- quired of the piston 2 cylinder further mini- only senses driver inputs through the gear ed to find solutions for this application sce- ments near the slave cylinder, which like- mizes travel. selector. The CbW offers similar possibilities nario. The basic concept devised is shown wise lead to moderate results. To counteract these drawbacks, design at comparable cost. Although the driver work is being carried out on an alternative must engage the clutch, all direct actuations Master cylinder connection variant that does not call for the release sys- of the clutch are executed by an actuator as Piston 1 tem to be permanently split into two sepa- is the case with the ECM. rate parts (Figure 14). The result is a direct The new MTplus concept was devised Carrier ring fluid path extending from the master to the to offer a cost-effective alternative with a re- slave cylinder (blue arrow) during foot-oper- duced functional scope by partially auto- Reservoir connection ated actuation, with minimal additional loss mating the clutch assembly. Unlike the ECM encountered. In automated mode, the ac- and CbW, the clutch is only automated tive intermediate piston blocks the inlet ac- when accelerating from a stop in gears 1, 2, cess point of the master cylinder and as- and R; when the driver shifts to higher sumes actuation of the clutch. Another gears, the clutch is operated manually only. problem area that needs to be addressed The design challenges specific to this con- Spindle drive Electrical connection for this concept is ensuring a smooth transi- cept are to provide for good operability Electric motor tion when a driver override input is received. while optimally coordinating actuator and To this end, different valve and reservoir ar- foot-operated actuation inputs. Further Slave cylinder connection Piston 2 rangements are currently being investigated analysis will be conducted in a trial test us- Figure 13 Actuator variant for MTplus with two intermediate pistons (not shown in Figure 14). ing a demonstrator. The following benefits 68 Manual Gearbox 4 69

manual transmission much more hybrid friend- CbW MTplus Improving the efficiency of ECM ly from an overall design perspective. A wide variety of technical features and options also the powertrain and the improves comfort and durability and can even be extended to include assistance systems. challenges to be overcome

The previous section already discussed the Looking optimistically importance of shifting the operating point of • 2-pedal design • 3-pedal design • 3-pedal design • Fully automated clutch • Fully automated clutch • Partially automated clutch into the future an engine to lower operating speeds • Actuator with high dynamics • Actuator with high dynamics • Actuator with reduced dynamics (downspeeding) in order to significantly re- • Gearshift intention detection • Pedal force emulator • Hydraulic connection between duce fuel consumption. For example, when • Gear recognition sensor • Gear recognition sensor pedal and clutch • Automated actuation for launch • Automated actuation for launch • Gear recognition sensor the mean operating speeds of a current and shifting and shifting • Automated actuation for launch The trend toward greater levels of automation 2.0-liter diesel engine are reduced by 10 %, only (gears 1st, (2nd), reverse) and electrification to reduce fleet consump- it is possible to consume 5.6 % less fuel un- tion also requires solutions for the manual der NEDC testing conditions. This potential Figure 15 Variations of clutch automation for manual transmissions transmission. Schaeffler is dedicated to find- can only be tapped, however, if doing so ing these solutions by promoting technical does not lead to any drawbacks in driving are achieved in comparison to an ECM or –– No possibility of a breakdown should developments for automating the clutch. In dynamics or comfort. Thus, to ensure that CbW: the actuator system fail the process, the effects on the overall power- these driving dynamics remain fairly consis- –– Lower cost thanks to reduced actuator All three systems offer comprehensive func- train cannot be overlooked. For example, fur- tent and comparable, the same output must requirements (dynamic response and tionality (Figure 16). This especially applies to ther reducing consumption by adding longer be achieved when the engine operates at a application times) the options available for reducing consump- gear ratios leads to increased engine excita- speed that is 10 % lower, which is why max- –– Mechanical override capability (re- tion, which are supported by each system. The tions as a result of lower operating speeds, imum torque must also be increased by ap- duced functional safety requirements) sailing and other functions offered make the which in turn necessitate better operative proximately 10 % (Figure 17). characteristics of the torsion dampers. Driving without clutch pedal 600 Optimal Consumption pedal force

Microslip NEDC ECM 100 Traction Anti-judder 400 -5.6 % control control -11 %

CbW Electric clutch Impact Tip-in/back-out during gear shift protection damping 90 Longer drive ratios 200

Engine torque in Nm Sailing 80

800 Consumption in % Regeneration Stall prevention 900 1.000 MT plus Electric Automated Resonance Collision 70 launch/creeping launch drive protection 0 1,000 1,500 2,000 Hybrid Autonomous Clutch Pedal force Emergency Engine speed in rpm Today's engine capability driving protection assistance braking 10 % operating point shifting Constant power Extreme downspeeding Concept CO2 potential Assistance Protection Comfort Safety

Figure 16 Functions afforded by clutch automation Figure 17 Operating point shifting and potential reduction in consumption with downspeeding 70 Manual Gearbox 4 71

In addition, it is foreseeable that usable even intentionally avoid low engine speeds for Full-load Down- speeds will be expanded much further this reason and thereby not profit from the characteristic speeding Yesterday

Torque down in the rev range. Some engines in the lower fuel consumption otherwise possible. Nm in

Torque Fewer Nm in future will even reach their peak torque at Further downspeeding amplifies the situa- cylinders 300 2008 300 Higher Torsional sensitivity damper below 1,000 rpm! Compared to today’s en- tion disproportionately (red line). When maxi- 1990 gines, this will allow these power units to mum torque is available below 1,000 rpm, the 100 100 0 0 theoretically reduce their consumption by comfort target at this speed is undershot by 1,000 4,000 1,000 4,000 11 % under NEDC testing conditions. more than 600 %. In order to achieve an ac- Engine speed in rpm Engine speed in rpm Such engine developments ultimately ceptable comfort level with these engines, lead to considerably higher vibrations from performance-oriented damper systems must Dual-mass the powertrain. This initially becomes evi- be fitted and are critical to ensuring that the 1985 ﬂywheel (DMF) dent in the rotational irregularity that in- consumption benefits afforded by downspeed- creases proportionately to an increase in ing can, in fact, be realized. torque or a drop in engine speed. Adding to this is the fact that as engine speed goes down, the excitation frequency becomes DMF + Prim. Sec. Vehicle Trans. more closely aligned with the natural fre- Vibration isolation – centrifugal 2008 pendulum quency of the rest of the powertrain. State of the art Tomorrow absorber Figure 18 summarizes the effects on the rotational irregularity in the powertrain. Relative ? to a current engine (green line), the oscillation range at the transmission input doubles for the Some 20 years ago, the requirements Figure 19 Dramatic increase in performance requirements for vibration-dampening systems same damper technology when engine speed placed on damper technology dramatically is reduced by 10 % (blue line). This marks the rose as a result of the direct-injected diesel This shift in engine technology presented experience torsional vibrations that can- starting point at which target comfort levels can engines then offered for passenger cars the developers of these systems with en- not be counteracted with a DMS alone. no longer be attained. Some drivers would (Figure 19). tirely new challenges. The resulting rota- The answer to these increased require- tional irregularity could not be sufficiently ments is the centrifugal pendulum ab- 100 Extreme downspeeding counteracted using the available torsion- sorber (CPA), which is a damper assembly 1,000 damped clutch disks. Although the princi- that introduces additional mass external 800 Δn ple of the low-pass filter was known, it was to the power flow. The dual-mass flywheel not regarded as being technically feasible and centrifugal pendulum absorber have Speed 300 until the dual-mass flywheel (DMS) was in- been continually refined and advanced Time troduced in passenger-car applications. and will meet the requirements associated 10 % Operating point shifting By leveraging its comprehensive knowl- with the upcoming evolutionary stages set 50 1,200 edge of the operating principles of passive for the current generation of engines [7]. 900 damping systems, LuK systematically The next engine generation, however, started investigating the underlying corre- which is currently under development, Speed Δn peak to in rp m 300 lations early on and was consequently able will call for vibration isolation measures Time to offer a compatible solution that met the that are even more capable, which is why emerging challenges in good time. Many Schaeffler is not only investigating the 1,200 Today's engine 0 years of know-how in metalworking then possibilities and constraints of today’s 1,000 finally led to a robust product. technology, but is also looking at alterna- 800 900 1.000 In the years that have passed, specific tive solutions. Speed Engine speed nEng in rpm 300 torque outputs have more than doubled in Time comparison to the first turbocharged, di- Target Engine Transmission rect-injection diesel engines. The resulting Figure 18 Rotational irregularity at the engine and transmission input for current and future engines effect is that even today, some engines 72 Manual Gearbox 4 73

Alternative solutions – Stiffness /17 Anti-resonance – Principle of Absorber Basis Mass x 3.5 interference Basis Options and the operating The following describes two concepts for principles that define them or generating anti-resonance: The spring-mass absorber and the summation damper. Although both concepts use a different Before implementation concepts are consid- operating principle, they produce similar ered at product level, the operating principles results under the same conditions. that govern them must be thoroughly evalu- ated with respect to future requirements. It is The Spring-mass absorber in this context that the method that uses The spring-mass absorber is based on a simple, linearized models to investigate the second spring-mass system. When this relative operating principles has proven suc- system is excited at its resonance frequen- cessful. Not only the technical potential of the cy, an opposing oscillation is generated that Amplitude different approaches must be factored into Amplitude ideally completely cancels out the original the overall assessment, however, but also excitation. With a conventional absorber 800 1,000 1,500 1,800 2,000 their cost-benefit ratio, whereby the objective 800 1,000 1,500 1,800 2,000 connected via a spring, this effect occurs at must always be to find approaches that offer exactly one frequency – the resonance fre- Engine speed n in rpm Engine speed n in rpm Eng equal, uniform performance across an en- Eng quency of the absorber. The drawback is an Target Basis gine’s entire operating speed range. Im- additional resonance point above the ab- Target Basis Mass x 3.5 or Stiffness /17 Absorber provements made at very low engine speeds sorber resonance frequency. are not optimal if they compromise the prog- Figure 20 Isolation capacity and limitations of A conventional absorber is therefore not Figure 21 Principle and isolation effect of a ress already achieved in the mid and high- the spring-mass system a suitable means of reducing torsional vi- conventional absorber speed ranges. In addition, only those solu- brations in the powertrain. What is required tions that comply with the restrictions for tions that are encountered as a result, is a absorber whose dampening frequency ure 22), which restoring force is dominated installation space and weight and are just as dampers demonstrate overcritical perfor- corresponds to the ignition frequency of the by the centrifugal force of the absorber robust as current systems when it comes to mance, and provide better isolation as fre- engine at all times. This property is fulfilled mass. Since the centrifugal force changes friction, wear, and manufacturing tolerances quency increases. When frequency drops, by the centrifugal pendulum absorber (Fig- quadrically in relation to the engine speed, are promising candidates. the resonance frequency is more closely The following systems will be investigat- aligned with these excitations and torsional Absorber Centrifugal pendulum absorber ed to determine whether (and under which vibrations become more prevalent. J conditions) their physical potential is capa- Theoretically, it is also possible to use a c ble of isolating the torsional vibrations of a spring-mass system to reach the required motor that utilizes an extreme downspeed- target even in extreme downspeeding sce- L ing concept so that comfortable driving is narios. This, however, would require the possible from 800 rpm. mass to be increased by a factor of 3.5 or l

the spring rate to be reduced by a factor of Amplitude c L f ~ f ~ n · 17 compared to the base construction. A J A l Spring-mass system – Principle of Neither is realistic. Arguments not in favor fA - Anti-resonance frequency the dual-mass flywheel of increasing mass are the increased installation space required, added weight, The basic operating principle of this ar- and worse driving dynamics. Reducing the 1,000 1,500 2,000 rangement is that two masses connected to spring rate by an extreme amount is also 800 Engine speed n in rpm each other by a spring-damping system os- not possible as a result of the installation Target Eng cillate against one another. In terms of the space problem and the compromised driv- CPA operating range used today and the excita- ing experience that would result. Figure 22 Centrifugal pendulum absorber (CPA) as a speed-dependent absorber 74 Manual Gearbox 4 75

J eff trinsic. The mass of the pendulum can also J(Sec+CPA) J only be increased to a certain extent due to i =0 15 M c i M JSec Jeff the installation space available. Whether the CPA can produce a vibration =ˆ isolation that is also compatible with the ex- 10 i =1 citations of the next generation of engines is JCPA not entirely clear at present. Recent im- 5 provements made to the system support φ this working hypothesis, however. c 2 ∆M 1 1 0 ( i - 1 ) Nevertheless, Schaeffler also continues f = c0 = A 2π J · i ∆φ 0 1,000 1,500 2,000 to search for alternative approaches. Using mass intelligently is the key to implementing Engine speed n in rpm fA = Anti-resonance frequency c0 = Effective stiffness Eng future solutions. Figure 23 Equivalent effective mass inertia of a Figure 25 Variations in spring arrangement for the summation damper centrifugal pendulum absorber The summation damper Another way of dampening vibrations with As in the case with a conventional absorber, the concepts, but also an identical transfer the centrifugal pendulum absorber has a anti-resonance is to add two vibration paths a summation damper can also decouple response. absorber frequency that is proportionate to together. Figure 24 charts this principle. Vi- 100 % of vibrations but only for a single fre- When the transfer response for design this speed. This is the ideal property or at- brations are transferred via a spring-mass quency. The summation damper therefore concepts with different anti-resonance tribute for reducing torsional vibrations in system along the one path and directly to a has an advantage over the absorber in that points is considered, the typical properties the powertrain, since a fixed excitation or- lever on the other. The pivot point of the le- no additional natural frequency is generat- of a summation damper become apparent. der can be dampened. ver (summation unit) is void of force and mo- ed. Unwanted vibrations above and below Anti-resonance frequencies can theoreti- Figure 23 shows how effective the mass tion from a dynamic vibration perspective. the anti-resonance frequency remain pres- cally be shifted to any low engine speed. of a centrifugal pendulum absorber is. The ent, however. Doing this, however, not only reduces the graph depicts, in relation to the engine Summation damper The frequency to be isolated, or target- absorbtion width, but also the isolating Basis speed, by what factor the secondary mass ed, can theoretically be selected as re- properties above the anti-resonance fre- would have to be increased for similar per- quired. When coordinating the system, the quency (Figure 26). This, in turn, means that formance – e.g. by a factor of 3 at a speed J summation damper provides one additional a summation damper configured for very of 1,000 rpm or a factor of 9 at 1,500 rpm. parameter not available with the conven- low anti-resonance responds sensitively to With a CPA, a vibration isolation figure of tional absorber – the lever ratio in addition to fluctuating parameters. A satisfactory solu- 100 % could theoretically be achieved up the spring rate and the rotary mass (J). An- tion can only be achieved if at least one of on a defined frequency. In demonstrator ve- other benefit is that the system can also be the three relevant parameters is variable hicles, a decoupling performance rating of configured so that a dampening effect is with respect to engine speed. up to 99 % was already demonstrated in achieved on the primary side (engine side). In a direct comparison, the summation conjunction with a DMF. This, in turn, makes Further arrangements are possible in damper has a slightly higher theoretical it easy to meet the requirements of today’s addition to the summation damper charac- potential for dampening vibrations than the engines and their upcoming evolution stag- terized in Figure 24. For example, the spring conventional damper (Figure 27). Having es. Current systems are even capable of can be positioned at any point required (Fig- said this, the advent of the centrifugal pen- Amplitude fulfilling the requirements of two-cylinder ure 25). Comprehensive testing has re- dulum absorber has already provided a so- engines. The potential offered by the CPA is vealed that the same basic laws and princi- lution for realizing a variable-speed damp- described in an additional article in this 800 1,000 1,500 1,800 2,000 ples apply irrespective of the positional er and is currently being used in volume book [7]. Engine speed nEng in rpm arrangement of the spring. The anti-reso- production applications. Variable-speed When engine speed drops, the centrifu- Target Basis nance frequency can even be calculated for summation dampers, on the other hand, gal pendulum absorber must absorb more Summation damper all concepts using a single formula. Assum- have yet to be integrated. energy. The ability of this pendulum to re- ing that the lever ratio, spring capacity, and spond depends on the mass involved and Figure 24 Principle and isolation effect of a mass J do not change, not only is the same the vibration angle, whereby the latter is in- summation damper anti-resonance frequency yielded for all of 76 Manual Gearbox 4 77

Summary mass flywheel in conjunction with a centrifugal pendulum absorber is a prime candidate, the summation damper is also worth consid- ering if a way can be found to extend its high

In the race to achieve global CO2 targets, au- potential at low operating speeds to mid- tomatic transmissions have clearly taken an range and higher speeds. Schaeffler contin- early lead as they allow engineers to develop ues to investigate both concepts with a great fuel-saving strategies by decoupling the en- deal of interest. The key to developing a more

Amplitude Absorbtion width gine from the transmission. The manual trans- responsive summation damper lies in the abil- mission also offers certain benefits, however, ity to vary one relevant parameter with respect including reliability, durability, and a low price, to engine speed. A solution that is robust, af- the latter of which continues to appeal to buy- fordable, and can be deployed on a large ers of small vehicles in particular. The logical scale has not yet crystallized, however. next step of advancing the technology of the 1,000 1,500 2,000 proven manual transmission must therefore focus on automating the clutch so that the Engine speed nEng in rpm Target driving strategies explored here can also be Literature Summation damper Anti-resonance frequency implemented in vehicles with manual transmissions. In addition to offering technical solu- Figure 26 Influence of the anti-resonance frequency on the absorbtion width tions that have already been developed (ECM, CbW), Schaeffler is working on systems that, [1] Gutzmer, P.: Individuality and Variety. when scaled down in scope, largely maintain 10th Schaeffler Symposium, 2014 the price advantage that a manual transmis- [2] Kremmling, B.; Fischer, R.: The Automated Constant parameters Speed-dependent parameters sion has over its automatic counterpart. Clutch. 5th LuK Symposium, 1994 Automated clutches are not only capable [3] Fischer, R.; Berger, R.: Automation of Manual of decoupling the engine from the rest of the Transmissions. 6th LuK Symposium, 1998 powertrain, but also actively support and fa- [4] Welter, R.; Herrmann, T.; Honselmann, S.; X cilitate many other comfort and protective Keller, J.: Clutch Release Systems for the functions. Automating acceleration from a Future. 10th Schaeffler Symposium, 2014 stop, for example, can prevent the clutch from [5] Müller, M.; Kneissler, M.; Gramann, M.; Esly, N.; Absorber Daikeler, R.; Agner, I.:Components for Double Amplitude being overloaded or misused, which in turn Amplitude allows the powertrain to be configured differ- Clutch Transmissions. 9th Schaeffler ently so that longer gear ratios can be imple- Symposium, 2010 1,000 1,500 2,000 1,000 1,500 2,000 mented to further reduce fuel consumption. [6] Müller, B.; Rathke, G.; Grethel, M.; Man, L.: Engine speed n in rpm Engine speed n in rpm Eng Eng th The operating point of the internal com- Transmission Actuators. 10 Schaeffler bustion engine then shifts to lower speeds Symposium, 2014 and specific torque is increased. Both mea- [7] Kooy, A.; The Evolution of the Centrifugal Pen- sures lead to more pronounced rotational ir- dulum Absorber. 10th Schaeffler Symposium, regularity, however. The resulting higher de- 2014 sign requirements for mechanisms that isolate [8] Fidlin, A.; Seebacher, R.: DMF Simulation Tech- ? frequencies will nevertheless be reliably met niques. 8th LuK Symposium, 2006 Amplitude Amplitude by current technology as it is incorporated into [9] Kroll, J.; Kooy, A.; Seebacher, R.: Torsional today’s engines and those targeted for the Vibration Damping for Future Engines. Summation damper th 1,000 1,500 2,000 1,000 1,500 2,000 next evolution stage. The problem revolves 9 Schaeffler Symposium, 2010 around the next generation of engines, which [10] Reik, W.; Fidlin, A.; Seebacher, R.: Gute Engine speed nEng in rpm Engine speed nEng in rpm will require even more capable systems. Al- Schwingungen – böse Schwingungen. VDI- Figure 27 Evolution of the absorber and summation damper though the technology offered by the dual- Fachtagung Schwingungen in Antrieben, 2009