Double clutch transmission can be divided into wet dual clutch transmission and dry dual clutch transmission. Difference between the two: in terms of working principle and basic structure, there is no essential difference between dry dual clutch transmission and wet dual clutch transmission. The difference lies in the cooling mode of dual clutch friction plate: the two sets of clutch plates of wet clutch are in a sealed oil groove and absorb heat through the transmission oil soaked with clutch plates, while the friction plate of dry dual clutch transmission has no sealing oil groove requires air cooling to dissipate heat.
As the name implies, the key technology of double clutch transmission is dual clutch, that is, there are two clutches, one is responsible for odd gear (1, 3, 5, 7 gears), and the other is responsible for even gear (2, 4, 6 gears). It can be imagined that the function of two manual gearboxes is combined into one and built in a single system. It has no hydraulic torque converter and no planetary gear group. At first glance, the gear part looks like a manual transmission because it has a synchronizer. But the difference is that it uses a 'double' clutch to control the power on and off of the engine. The two automatically controlled clutches, driven by electronic control and hydraulic pressure, can simultaneously control the operation of the two sets of clutches.
After the double clutch transmission is switched to the second gear, the odd gear clutch (red) is disconnected, and the power is transmitted to the even gear clutch (green) for the second gear operation. When the transmission operates, a set of gears are engaged, and when it is close to the shift, the next set of gears have been selected in advance, but the clutch is still in the disengaged state; When shifting, one clutch will separate the gears in use, and the other clutch will engage the pre-selected gears. These four actions are carried out simultaneously under the control and action of the electronic control unit. Therefore, the speed change response is very fast. During the whole shift, it can ensure that at least one group of gears is outputting power, and the power will not be interrupted in theory.
To cooperate with the above operation, the transmission shaft of DSG is divided into two parts. One is the transmission shaft placed in the inner solid, and the other is the hollow transmission shaft outside. The inner solid drive shaft is connected to 1, 3, 5 and reverse gear, while the outer hollow drive shaft is connected to 2, 4 and 6 gears. The two clutches are responsible for the meshing action of one drive shaft, and the engine power is transmitted uninterruptedly by one of the drive shafts.
Taking the gearbox of Ford 6-speed double clutch transmission as an example, it contains two automatic control clutches, which are driven by electronic control and hydraulic pressure, and can control the operation of the two clutches at the same time. When the transmission operates, a set of gears is engaged. When close to shifting, the next set of gears have been selected in advance, but the clutch is still in a state of separation. When shifting, one clutch separates the gears in use, and the meshing of the other clutch has been pre-selected. During the whole shifting period, it can ensure that at least one set of gears is outputting power, so there is no power interruption. In order to cooperate with the above operation, the transmission shaft of the double clutch transmission is divided into two parts when it moves, one is the solid transmission shaft, and the other is the hollow transmission shaft. Solid drive shafts are connected to 1, 3, 5 and reverse gear, while hollow drive shafts are connected to 2, 4 and 6 gears. Each clutch is responsible for the meshing action of one drive shaft, and the engine power is transmitted uninterruptedly by one of the drive shafts.