ABSTRACT Hydrodynamic launch elements, from the Foettinger principle of the torque converter to the first series production HCC wet clutch, are becoming more relied on in the transmission world for their high power density, launch comfort, and vibrational isolation capability. In order to attain the ambitious fuel economy objectives of the future, engine vibrations have to be successfully isolated from the driveline at low engine speed ranges without the use of the hydrodynamic circuit. This is now all the more challenging as new combustion engines are producing higher torsional vibrations as a result of fewer cylinders, higher combustion pressures, cylinder deactivation, and lower critical speeds. This paper will describe the next generation of powertrain vibrational isolation, dampening via powersplit. Additionally, a next generation wet launch element, the Hydrodynamically Cooled Clutch will be discussed. A brief description of the current state of the art dampening technologies will be reviewed, highlighting the limitations of these solutions which pave the way for the new generations. The challenge with front wheel drive or hybrid layouts is to reduce the dimensions of the hydrodynamic and clutch systems, while sustaining high thermal capacity in order to improve vibrational isolation, and ensure protection against judder in a challenging packaging environment. INTRODUCTION High gasoline prices and government regulations continue to demand additional improvements in light vehicle fuel economy. The optimization of powertrains - engines and transmissions - is an effective way to achieve further improvements. With automatic transmissions being the dominant transmission concept for light vehicles in the NorthAmerican market there is still potential to improve the efficiency of the powertrain with the help of the transmission and its components. Engine downsizing is a growing trend: Cylinder deactivation for 8- and 6-cylinder internal combustion engines has been state-of-the-art for some time now. The same is true for the application of turbo- or supercharging and with that the reduction of engine displacement and number of cylinders (8 -> 6 -> 4 -> 3/2). The drawback of these measures is generally a drastic increase in torsional irregularities produced by the engines. At the same time engine torque levels are still increasing, while the space available for powertrain components becomes more scarce. While torque converters are still the dominating launch elements in automatic transmissions in the North American and Asian markets their functionality is changing. With increasing transmission gear ratios and growing engine torque plateaus the need for torque multiplication and thus big hydrodynamic circuits (in many passenger car applications) is decreasing. However, smooth vehicle launch and creeping capability are functions that are demanded by the drivers and have to be mastered by a launch element despite the demand for increased fuel economy. The increase in torsional irregularities have shifted the development focus for torque converters towards the integrated torsional dampers. Not only will the torsional dampers become more capable but they will demand more space within the launch device. As a result less space will be available to transfer or multiply torque with a hydrodynamic circuit. New Launch Devices for Automatic Transmissions2013-01-0233 Published 04/08/2013 Scott William Binder, Matthias Fischer, Christoph Sasse and Joerg Trampler ZF Friedrichshafen AG Copyright © 2013 SAE International doi:10.4271/2013-01-0233Downloaded from SAE International by Univ of Nottingham - Kings Meadow Campus, Saturday, August 11, 2018Current Torsional Dampers in Torque Converters This section will give a brief overview of the state-of-the-art in torsional damping technology implemented in torque converters for automatic transmissions. Standard Torsional Damper The standard torsional damper in a torque converter consists of a