One clutch is responsible for odd gears (1, 3, 5 and 7 gears), and the other clutch is responsible for even gears (2, 4 and 6 gears). It is conceivable that the functions of two manual gearboxes are integrated into one system, without torque converter and planetary gear set.
From the gear part, it looks like a manual gear at first glance because it has a synchronizer, but the difference is that it uses a "double" clutch to control the on-off of engine power. These two automatic clutches are driven by electric control and hydraulic pressure, which can control the work of two sets of clutches at the same time.
After shifting to the second gear, the odd clutch (red) turns off the power and transmits it to the even clutch (green). When the gearbox is running, one set of gears is engaged, and when it is close to shifting, the gear of the next set of gears has been pre-selected, but the clutch is still in the disengaged state;
When shifting gears, one clutch is disengaged from the in-use gear and the other clutch is engaged with the pre-selected gear. These four actions are all carried out at the same time under the control and action of the electronic control unit, so the shift response is extremely fast, and at least one gear can output power during the whole shift period, and theoretically there will be no power interruption.
Advantages:
1, the dual-clutch gearbox combines the advantages of manual gearbox and automatic gearbox, and uses two sets of clutches instead of torque converter, and achieves the effect of shifting gears without gap through the alternating work of the two sets of clutches.
2. Because there is no torque converter, the power of the engine can be fully exerted, and at the same time, two groups of clutches work alternately, which makes the shift time extremely short and the power failure of the engine is very limited.
3. Because the gear shifting is more direct and the power loss is smaller, the fuel consumption can be reduced by more than 10%.
Disadvantages:
1, because there is no hydraulic torque converter, it is impossible to realize the "semi-trailer" action of manual transmission. For small displacement engines, the characteristics of insufficient low-speed torque will be completely exposed.
2. Because the dual clutch is controlled by a computer and belongs to an intelligent transmission, it needs to send an electronic signal to the engine when upshifting/downshifting. After the engine is restored, it can cooperate with the engine to complete the upshift/downshift. The use of a large number of electronic components also increases the probability of failure.