Dual Clutch Transmissions - Lessons Learned and Future Potential 2005-01-1021
Dual Clutch Transmissions (DCTs) are providing the full shift comfort of traditional step automatics but offer significantly improved full efficiency and performance.
With up to 15% better fuel efficiency compared to planetary-ATs, the DCTs are the first automatics to provide better values than manual transmissions. Higher top speed and, more important in everyday driving, better acceleration compared to planetary-ATs and CVTs are additional benefits.
DCTs are also the first automatic transmissions well suited for high torque Diesels and high revving gas engines alike.
The DCT concept was originally developed in the 1940's but it took until recently that high volume production solutions were made possible and allowed for the mainstream vehicle market entry.
Beside the electronic hard- and software the key enablers for the DCT are the dual wet clutch and the electrohydraulic transmission control module.
On the clutch side new friction elements have been designed. Combined with an enhanced transmission fluid more than two million shifts per clutch and a consistent launch quality over the transmission lifetime are achieved.
The dual clutch design itself supports very responsive clutch engagements and disengagements as well as good controllability under slipping conditions.
On the controls side the electronics, sensors and electrohydraulics have been integrated into a mechatronic module for minimized tolerance bands and improved reliability.
Low hysteresis, direct acting solenoids enable the precise and fast clutch control that is the key for the DCT function.