ABSTRACT This paper presents an alternative launch device for layshaft dual clutch transmissions (DCT's). The launch device incorporates a hydrodynamic torque converter, a lockup clutch with controlled slip capability and two wet multi-plate clutches to engage the input shafts of the transmission. The device is intended to overcome the deficiencies associated with using conventional dry or wet launch clutches in DCT's, such as limited torque capacity at vehicle launch, clutch thermal capacity and cooling, launch shudder, lubricant quality and requirement for interval oil changes. The alternative device enhances drive quality and performance at vehicle launch and adds the capability of controlled capacity slip to attenuate gear rattle without early downshifting. Parasitic torque loss will increase but is shown not to drastically influence fuel consumption compared to a dry clutch system, however synchronizer engagement can become a concern at cold operating temperatures. The performance of the dual clutch torque converter is assessed in a 7 speed front wheel drive DCT application and compared against the dry clutch system in the areas of launch, start/stop, driveline torsional isolation, gear rattle mitigation and fuel consumption. The dual clutch torque converter is shown to overcome the shortcomings of a dry friction launch system and deliver equivalent fuel economy performance. INTRODUCTION Dual clutch transmissions are steadily gaining market share with the increased focus on improving overall powertrain efficiency to reduce emissions and fuel consumption. Dry or wet DCT's (dDCT or wDCT, respectively) hold an inherent spin loss advantage over planetary gear set automatic transmissions due to the mechanical design of the transmission. The use of splash lubrication, low power consuming hydraulic or electro-mechanical actuators for thetorque transfer devices, greater ratio selection flexibility and virtually no clutch drag are the main contributors to the advantage over planetary automatics; see [ 1 and 2]. Wet DCT's, however, have a slight decrease in mechanical efficiency (fuel economy) compared to dDCT's because a higher capacity pump is required to supply continuous apply pressure and cooling flow to the clutch pack, [ 3]. When compared to planetary type automatic transmissions, DCT's have performance advantages with reduced shift times, minimizing torque interrupt and lower reflected inertia at the input shafts. However, dry or wet DCT's have a few mechanical and drive quality concerns when compared to planetary automatics, namely lack of sustained vehicle creep on grade, hill hold capability, towing capability, clutch thermal capacity, launch shudder and degradation in perceived launch performance. The DMF assemblies required to mitigate gear rattle can have adverse effects on packaging, 12V start/stop integration and can add significant inertia/mass to the drivetrain hindering acceleration performance and increasing fuel consumption. Additionally, for wDCT's, high quality lubricating oil is required to achieve adequate friction and cooling characteristics which requires interval changes, leading to increased initial and routine maintenance costs. The goal of this paper is to demonstrate that the use of a torque converter with integrated wet shifting clutches within a single pressure vessel can be beneficial to drive quality without negatively affecting fuel economy. This alternative device will hereafter be referred to as a dual clutch torque converter, DCTC. The performance of the DCTC will be compared against a dry clutch system for a front wheel drive (FWD) 7 speed DCT. The performance characteristics to be assessed include launch, 12 volt start/stop, driveline isolation, gear rattle mitigation, and fuel consumption on the FTP city- highway schedule. A Dual Clutch Torque Converter for Dual Input Shaft Transmissions2013-01-0232 Published 04/08/2013 Darrell Robinette and Ted Skrzycke General Motors Company Copyrig