People familiar with and knowledgeable about automobiles should know that the gearbox is the driving part of a car, which can transmit the engine's power to the wheels as required.
The twin-clutch transmission consists of a dual-mass flywheel, dual clutches, dual clutch actuators (controlling the engagement and separation of clutch 1 or clutch 2), a gearbox with dual power inputs, and a gearbox shift actuator (hydraulic or electric). The power is transmitted from the engine through the dual-mass flywheel (which has a damper that can filter out unstable torque fluctuations from the engine) to the dual clutches. If the odd-numbered (odd) gear is selected, the corresponding odd-numbered (odd) clutch of the dual clutches engages, and the power can be transmitted to the odd-numbered (odd) power input shaft of the gearbox, and then power is outputted from the corresponding gear. Similarly, when the even-numbered (even) gear is selected, the power is transmitted from the even-numbered (even) clutch of the dual clutches to the even-numbered (even) power input shaft of the gearbox, and then power is outputted from the corresponding gear.
It should be noted that before the clutch (either odd or even) of the dual clutches engages, the synchronizer of the corresponding gear needs to enter the meshing state in advance. During the gear-shifting process, only the engagement and separation status of clutch 1 and clutch 2 are switched. Usually, when one clutch is released, the other clutch synchronously engages. In this process, there will be a state where both clutches simultaneously transmit torque. However, the proportion of transmission is different. This is also the advantage of the automotive twin-clutch transmission in terms of driving performance compared with a normal MT gearbox.
The gearbox structure of twin-clutch transmission is similar to that of a normal MT gearbox, relying on the shift fork to change whether the synchronizer of the gear engages or releases. The difference is that the gear-shifting fork of MT is manually shifted, while the gear-shifting fork of twin-clutch transmission is shifted by an electronic actuator. This is similar to the working process of AMT gearbox's gear-shifting fork.
Since the gearbox structure of twin-clutch transmission is similar to that of MT or AMT, it means that it has the advantages of high transmission efficiency and low fuel consumption compared with other AT or CVT gearboxes, and the advantage of better shift smoothness and higher comfort than AT and CVT gearboxes compared with MT or AMT. This is also why more and more mainstream market models began to equip twin-clutch transmission in recent years. In addition, since the automotive twin-clutch transmission must be equipped with dual-mass flywheels and dual clutches, and has a complex structure, the manufacturing cost may be higher than other gearboxes, which is also a factor affecting the market share of twin-clutch transmission. However, with the maturity and innovation of technology, this factor will gradually become smaller.
Currently, there are two types of mainstream automotive twin-clutch transmission: dry twin-clutch transmission and wet twin-clutch transmission. The gearbox structure and working principles of these two gearboxes are the same, except for the different types of dual clutches, namely dry dual clutches and wet dual clutches. The characteristics of each type will be discussed below.