Overview
This document contains information on:
General
Function requirements
Function
General
The dual clutch is used to transfer engine torque non-positively from the engine to the respective transmission input shaft of the corresponding sub-transmission. The dual clutch performs the following basic tasks:
Disconnects and connects power flow between engine and transmission
Transfers engine torque to one of the two sub-transmissions
Starting off and fast gear change without interruption of tractive power
Additional vibration decoupling through operation with microslip (vibration decoupling is mainly achieved through two-mass flywheel)
The two clutches in the dual clutch have the following specific tasks:
Clutch K1 (outer clutch): Connect power flow, change gear and transfer torque, e.g. in 7-speed dual-clutch transmission, in 1st, 3rd, 5th and 7th gear
Clutch K2 (inner clutch): Connect power flow, change gear and transfer torque, e.g. in 7-speed dual-clutch transmission, in 2nd, 4th, 6th gear and in reverse gear
Function requirements
Engine management ON (circuit 87M)
Engine in operation
Example illustration of dual-clutch transmission |
1 | Dual clutch |
P27.20-2144-76
Function
The dual clutch (1) is a clutch module that consists of two combined multiplate clutch packs. To save space the multiplate clutch packages are built into each other. Each multiplate clutch is coupled with a sub-transmission. Sub-transmission 1 contains the odd forward gears, sub-transmission 2 the even forward gears and the reverse gear.
Each multiplate clutch package is operated by the fully integrated transmission control electrohydraulic controller unit or the dual-clutch transmission control unit. Clutches K1 and K2 are operated independently of each other.
The dual clutch is a wet one, i.e. the multidisk clutches are operated in an oil bath. The transmission oil is used for power transmission and for cooling the dual clutch.
The oil pressure required to compress the clutch plates is relatively low. This enables a high transmission efficiency rate to be achieved.