Schaeffler Innovations for Torque Converters Offer Significant Advantages with Regard to Energy Efficiency, Design Envelope, Weight and Performance
Resource from: Schaeffler Technologies Likes:228
Jan 14,2014
Integrated torque converters – performance and efficiency with low space requirements
Most new vehicles registered in North America are equipped with an automatic transmission with a torque converter. This is an area in which Schaeffler has been making a decisive contribution towards reducing fuel consumption and thus CO2 emissions for decades with its innovations. These automatic transmissions, which were once branded inefficient, have been trimmed to exemplary levels of efficiency through continuous development work, so modern automatic transmissions with torque converters are no longer inferior to manual transmissions or double clutch systems when it comes to energy efficiency.
Torque converters have been primarily used in automatic transmissions and continuously variable transmissions for years. The converter is placed between the engine and the transmission, and transfers the engine torque to the transmission’s input shaft. This transfer takes place hydrodynamically during startup and via an integrated friction clutch to reduce fuel consumption during driving operation. The converter additionally increases the torque on the transmission input shaft by up to a factor of three during startup.
“The desire for greater driving performance, reduced fuel consumption and lower emissions, as well as the increasingly compact design envelope, mean that the design and conception of modern torque converters have to be subject to continuous development,” explains Marc McGrath, president Transmission Systems at Schaeffler North America.
Higher performance with a lighter and more compact design
A glimpse of the new W238 generation of torque converters clearly shows the progress that has been made in development. This current generation boasts the following key data: 530 Nm of torque and a hydraulic diameter of 238 millimeters. This is now combined with a weight of just 14 kilograms and a hydraulic element width of around 50 mm. The previous W258 generation still weighed over 17 kilograms with a diameter of 258 mm and was 70 mm wide. More compact, more lightweight, but still delivering higher performance – the comparison of the two generations makes a clear point.
Schaeffler has been strengthening its position in the USA with its own torque converter development and manufacturing location in Wooster, Ohio since 1998. Wooster plays the role of a competence center in Schaeffler’s global development network, which encompasses 40 locations and about 6,000 engineers and technicians. An important factor for the market success of LuK’s torque converters is their continuous further development. Our development expertise means we are always making significant technological advances, including innovative damping concepts like the centrifugal pendulum-type absorber (CPA) and new converter concepts like the integrated torque converter and the multi-functional torque converter. There are multiple approaches for further reducing weight, mass inertia and costs.
Innovative converter concepts
The integrated torque converter is a completely revised converter and clutch system in which the clutch function is carried out directly by the torque converter turbine instead of using a separate piston, as was previously the case. This reduces the weight and mass moment of inertia while making the design envelope smaller and making it possible to implement innovative damping concepts like the CPA without needing any additional space. Centrifugal pendulum-type absorbers have been successfully used in rear-wheel drive vehicles since 2010. The combination of an integrated torque converter and CPA means they will also become increasingly widespread in front-wheel drive vehicles.
The centrifugal pendulum-type absorber works as follows: In the new converters, a centrifugal pendulum-type absorber is located on the turbine side and operated in the oil chamber. A spring damper provides basic isolation of vibrations when the lockup clutch is closed and the residual irregularities are almost totally canceled out by the centrifugal pendulum-type absorber. This way, the maximum speed fluctuations in the differential input can be reduced by more than 70 percent compared to a conventional damper – ideal prerequisites for reducing fuel consumption and CO2 emissions.
“The damper with a centrifugal pendulum-type absorber in the torque converter significantly improves the isolation of vibrations. This technology makes it possible to close the lockup clutch earlier and thus to simultaneously improve fuel economy and comfort,” explains Uwe Wagner, vice president Research and Development Automotive at Schaeffler. “This means that the CPA will be finding more widespread use in the torque converters of automatic transmissions in the future. And we will continue to further develop this technology in order to ensure that we maintain our competitive edge.”
The CPA is a finalist for the Automotive News PACE Award, which is presented annually in recognition of innovations in the automotive sector.
There is further converter innovation that is customized to suit modern, turbocharged engines and represents a revolutionary invention in the field of converters: “The multi-functional torque converter, or MFTC, is ideal for use in combination with start–stop systems and can compensate for the delayed response – known as “turbo lag” – that is commonly experienced,” explains McGrath.
Furthermore, fuel savings of up to five percent can be achieved with the multi-functional torque converter, the optional idle disconnect function, and early torque converter lockup. The MFTC eliminates converter idling losses because the transmission can be decoupled from the engine, and this arrangement also allows the mass moments of inertia to be distributed in a more beneficial way – the result is outstanding isolation of vibrations in all operating ranges. Because of this decoupling, the engine reaches higher starting speeds at the moment at which the torque converter is activated, which in turn significantly improves the starting performance of turbocharged vehicles and is a way to avoid the dreaded “turbo lag.”
Increasing market share for automation
In 10 years time, it is probable that more than 100 million vehicles per year will be produced worldwide and more than half of those will be equipped with automatic transmissions. Automatic transmissions with torque converters will make up the majority of this number at around 30 million. In other words, the volume of automatic transmissions with torque converters on the market is set to rise by 13 percent during this period. However, torque converters are also installed as a startup element in continuously variable transmissions. The number of CVTs is set to rise to 12 million (an increase of approximately 70 percent), thus probably surpassing that of double clutch transmissions – which during the same period will increase roughly threefold. Growth for these transmissions is mainly being generated in Europe and China.
“Legal boundary conditions mean that the trend towards automatic transmissions may well become stronger in the future because measures for further reducing emissions and fuel consumption are difficult to implement with manual transmissions,” explains Andreas Englisch, vice president Product Unit CVT and Converters at Schaeffler.
The chronology of torque converters at Schaeffler
1983 LuK produces the first dampers for automatic transmissions (customer: Ford).
1990 LuK begins developing torque converters.
1997 LuK begins volume production of the Allison torque converter.
1998 LuK begins complete in-house production of torque converters (customer: GM).
2001 Volume production of torque converters for GM begins in Wooster (USA).
2004 Volume production of the Ford 6R torque converter – used in the USA’s top-selling vehicle (the F150) – begins in Wooster (USA).
2004 Volume production of ZF torque converters begins in Bühl (Germany).
2004 LuK produces its one millionth torque converter.
2005 LuK produces 1 million torque converters per year.
2010 Volume production of torque converter dampers with CPA (centrifugal pendulum-type absorbers) begins in Europe.
2012 LuK produces 2.1 million torque converters and an additional 2.3 million lockup clutches/dampers per year worldwide.
2013 Volume production of torque converters with CPA in Wooster (USA).
2014 Torque converter production begins in Taicang, China.
(Schaeffler Technologies)
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1.The news above mentioned with detailed source are from internet.We are trying our best to assure they are accurate ,timely and safe so as to let bearing users and sellers read more related info.However, it doesn't mean we agree with any point of view referred in above contents and we are not responsible for the authenticity. If you want to publish the news,please note the source and you will be legally responsible for the news published.
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