Continuing just-auto’s series of interviews with transmission manufacturers, Matthew Beecham talked with Dr Hartmut Faust, Chief Engineer Technical Excellence & Advanced Engineering, Getrag, Uli Blessing, Senior Manager Programmes & Technology Strategy, Getrag, and Dr Ingo Steinberg, Platform Director DCT Transmissions, Getrag. In this interview, Getrag’s engineers talked DCTs and how their Powershift 6DCT250 transmission has pushed back the technical boundaries.
just-auto: Do you think that transmissions have more potential these days to help reduce fuel consumption and at a lower cost than, say, engine-internal measures?
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Getrag: Yes, besides engine downsizing the new technologies such as dual clutch transmissions (DCTs) significantly contribute to fuel consumption reduction. The main reasons for gaining good fuel efficiency are the absence of the torque converter slip loss and flexibility of gear ratios with high overall ratio spread combined with controllability of launch behaviour by electronics.
Compared with other automatic transmissions (ATs), DCTs enable engine start-stop without any additional electric driven pump or pressure oil accumulator needed. The opportunity of easy hybridisation delivers one further advantage, because the motor size can be minimized by connecting the motor to a certain path of the DCT with higher speeds instead of connecting to the lower engine crank shaft speed directly.
Vehicles containing the second generation of our DCTs even show lower fuel consumption and CO2 emissions in the driving cycle than the corresponding derivative with manual transmission.
just-auto: Although DCTs have high-speed resistance, they are still more expensive than torque converter transmissions (depending, of course, on the segment you are looking at). Or is all that price relationship changing?
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By GlobalDataDCTs are still more cost intensive as it is a complex technology and currently have a lower market share. DCT technology is still quite new in the market, but is received really well and worldwide volumes are growing fast. Therefore, the current cost advantage of the torque converter will disappear. CSM predict a growth of DCT share from 1% in 2010 to almost 8% in 2016. Our order book confirms this trend. With growing volumes, the cost differences to torque converter ATs will disappear. As mentioned earlier, DCTs do not need additional hardware enabling engine start-stop, while torque converter ATs requires an electric driven pump or an oil pressure accumulator.
just-auto: How do you see the global transmission market evolving in terms of manual, automatics, etc? And what do you see happening in those emerging markets such as China and India?
In Europe the DCTs are very well received by the customers, because the Powertrain response is “MT-like” and DCTs offer good efficiency. With the introduction of DCT technology, the market share of manual transmissions is decreased.
In the US, in some portion the market will stick to torque converter ATs. Sure, sports cars contain DCTs.
In Japan, for traffic jam reasons the customers will stay with CVTs, beneath the new technologies.
India will stay with manual transmissions mainly for the next decade.
In China, a strong trend from manual transmissions to DCTs can be recognised. Getrag are prepared to fulfil the corresponding customer demands in China.
just-auto: In terms of the future of manual gearboxes, some people expect manual transmissions to remain attractive in cost-sensitive markets while automated transmissions will gradual gain market share. Other people anticipate a gradually decreasing market for manual transmissions as drivers like the comfort and convenience while engineers like the ability to control the shift points in order to meet emissions and CO2 requirements. What do you anticipate will happen to the manual transmission market?
We expect a shift from manual transmissions to automated transmissions also in Europe, which has happened with the introduction of fuel efficient DCTs already. Nevertheless the manual transmissions will stay at very high volume. The market share of 6-speed manual transmissions versus 5-speed manual transmissions will increase further on.
In very cost sensitive markets, the manual transmissions, as the lowest cost solution, will stay the mainstream technology.
just-auto: Given the global economic climate, need to control emissions, demand from BRIC countries and increasing oil price, it suggests that no one transmission technology will be the winner. Would you agree?
Different markets require different technologies. It is absolutely important to understand the different market needs and expectations which can be fulfilled appropriately with DCTs.
just-auto: What do you expect to happen with CVTs in North America and Europe? Do you see CVTs having a brighter future in Japan where the roads are more congested with lower average speeds?
We expect that CVT will remain in his home market in Japan. In Europe, DCTs will increase while in North America the torque converter ATs will hold a high market share.
just-auto: We’ve seen the introduction of gearboxes with seven and eight speeds which can improve efficiency. From a technical point of view, I guess that gives the traditional planetary automatic a new lease of life? On the flipside, does the additional cost and weight of more gears cancel out the efficiency gains?
The increased number of speeds delivers a very low contribution to fuel economy improvement and is driven by marketing mainly. A key enabler to fuel economy improvement is the flexibility in gear ratios with high ratio speed, which is covered by DCT technology.
just-auto: Could you talk us through how Getrag’s Powershift 6DCT250 transmission differs from its closest rivals and pushes back the technical boundaries of the DCT arena?
The Getrag Powershift 6DCT250 is equipped with three features to reach highest level of fuel economy:
- Dry running dual clutch with lower drag torque compared to wet disk clutch
- Electro-mechanic clutch actuation not needing any pump drive
- Electro-mechanic on demand shift actuation with shift drum.
just-auto: In what ways are you developing and applying DCTs for hybrids?
DCTs are without mechanical changes ready for start-stop and dedicated for Mild, Full or Plug-In Hybrid functionality. Getrag uses high-speed e-machines for most of the applications to achieve a very good power density with low weight. For Full- or Plug-In Hybrid functionality the e-machines are connected to one part of the transmission. Thanks to the cooperation with Bosch on Hybrid and pure electric drivetrain integrated solutions can be developed on a platform base.
Besides the integration of an e-machine in a DCT, there is also the possibility to use one of Getrag’s various electric drivetrains as an axle split Hybrid
just-auto: How do you see the future for electronically-actuated AMTs, whether integrated into hybrid or electric powertrains or combined with a conventional internal combustion engine?
Due to high efficiency at low cost, also as an add-on unit to manual transmissions, AMTs might have a future in passenger cars. However, the shifting comfort is the major reason why the future is limited to entry level passenger cars.
Filling the torque-break is a big challenge to AMT hybrids. Interestingly the first axle split hybrids aren’t launched with AMTs.
Nevertheless AMTs will stay a mainstream technology in the truck business.
