Dual Clutch

Courtesy of NISSAN NORTH AMERICA, INC.

Instead of a conventional clutch with mechanical or hydraulic release mechanism like those usually installed on vehicles with manual transaxles, a dual clutch transaxle uses a clutch module with two combined multidisk clutches which are electrohydraulically actuated on alternating basis. Each multidisk clutch is coupled to a sub-transaxle 1 (K1 clutch engaged) contains the odd forward gears 1, 3, 5 and 7. Sub transaxle 2 (K2 clutch engaged) contains the even forward gears 2, 4, 6 and reverse gear. During driving operation and with the exception of reverse gear, only one gear of a sub transaxle is ever engaged, while the next expected gear is preengaged by the transaxle control system (associated clutch still open, no power transaxle takes place). Due to the high thermal load which arises when starting off in gear range "D" because of the frictional energy at the clutch plates, K1 clutch is located above K2 clutch. Due to this design measure, the friction surface of K1 clutch is correspondingly higher than that of K2 clutch, which reduces the specific thermal load. Starting off in gear range "R" is carried out via K2 clutch. This also results in high friction values and thus high temperatures at the clutch plates, but the effect of this is limited by the fact that the vehicle starts off less frequently in reverse gear. The main advantages achieved through these design features and functional characteristics include improved vehicle dynamics, greater comfort through jolt-free shifting, high efficiency and almost uninterrupted power transaxle.