The Volkswagen 7-speed dual clutch gearbox OAM is a follow-up development product of Volkswagen's direct shift gearbox (DSG) 02E. However, it is the first 7-speed gearbox for front transverse installation and uses a dry-type dual clutch as the dual clutch transmission. In terms of comfort and uninterrupted traction shifting, the new gearbox is the same as the direct shift gearbox, but its efficiency has been significantly improved, making an important contribution to reducing fuel consumption and emissions.
The total assembly quality of the Volkswagen 7-speed dual clutch gearbox OAM is about 70kg, with a maximum torque of 250N·m, 7 forward gears and 1 reverse gear, and a gear ratio range of 8.1. It adopts a dry-type dual clutch and a modular gearbox structure, and the clutch, mechanical-electronic unit and transmission constitute a unit respectively. The mechanical-electronic unit and mechanical gearbox have separate oil systems, which are filled once and do not need to be replaced, and there is no oil/water heat exchanger.
The dual clutch gearbox mainly consists of two independent sub-transmissions. The functional structure of each sub-transmission is the same as that of a manual transmission, and each sub-transmission has a dry-type clutch. The clutch is controlled, engaged and disengaged by the mechanical-electronic unit according to the gear position to be engaged. Gears 1, 3, 5 and 7 are changed by clutch K1 and sub-gearbox 1 and output shaft 1. Gears 2, 4, 6 and reverse gear are controlled by clutch K2, sub-gearbox 2 and output shaft 2 and 3. In principle, one sub-transmission always transmits power. The other sub-transmission has already been able to shift to the next gear, because the clutch of that gear is still in the disengaged state. Each gear position has a conventional manual transmission synchronizer and shifting unit.
The dual clutch gearbox is installed in the gearbox housing and consists of two traditional clutches combined to form a dual clutch. Clutch K1 transfers torque to input shaft 1 through a spline, and input shaft 1 continues to transmit torque of gears 1 and 3 to output shaft 1 and torque of gears 5 and 7 to output shaft 2. Clutch K2 transfers torque to input shaft 2. The latter continues to transmit torque of gears 2 and 4 to output shaft 1, and torque of gears 6 and reverse gear to output shaft 2. Then the torque is transmitted to reverse gear wheel R2 of output shaft 3 through reverse gear wheel R1 of reverse gear. All three output shafts are connected to the main reducer gear of the differential.
Torque enters the transmission through clutch K1 or K2. Each clutch drives an input shaft. The power transmission route to the differential is as follows: output shaft 1 for gears 1, 2, 3 and 4; output shaft 2 for gears 5, 6 and 7; output shaft 3 for reverse gear and parking lock.