Type and application of automatic transmission


At present, the automatic transmission in the market is mainly divided into: AMT (Automatic Mechanical Transmission), AT (Automatic Transmission), CVT (Stepless Transmission), DCT (Double Clutch Transmission, Volkswage DSG).

First let's talk about AMT (automatic mechanical transmission)


Accurately, AMT is not an automatic block. In fact, it is joined to join the servo shifting mechanism on the basis of manual gearbox. The structure is relatively simple, and the actual performance is also slower, and it is very strong, generally in low-end cars. Used, such as the old SMART can now be seen in the second-hand car market, the type and application of the automatic transmission of SAIC MG (Figure 2) MG3 (parameter | picture) 5 block AMT, and Haval's new H1 ( Parameters | Pictures Apply 6 block AMT.

AT (automatic gearbox):

The AT gearbox is used as the most traditional automatic transmission, which has been very mature today.


The automatic gearbox is widely used in many gearboxes, and the performance performance is balanced. The most common in the market is the 6AT gearbox. It is a 5AT gearbox, 4AT, 3AT is a relatively simple technology in the early years. It has applied 3AT gearbox in the earlier, and Outo, I have used 3AT gearbox. Many brands use 8at, 9at gearbox, which is reported to the new Honda Odyssey (parameter | picture) will be equipped with a 10AT gearbox. The advantage of the AT transmission is that the carrier torque is more mature relative to CVT and dual-clutch gearboxes. When the manufacturer does engine gearbox match calibration, it is relatively easier, but it is also necessary to arrange according to the replacement, and the maximum number of gear numbers is.

CVT (stepless gearbox)

The CVT continuously variable transmission has been used in recent years, mainly Japanese brand (Nissan, Subaru, Toyota, etc.) and some independent brands (Geely, Chery, etc.).


The principle of the CVT transmission is actually the same as our common pedal motorcycle, and the conventional gear is substituted with a pair of pulleys and a steel belt, each pulley, is actually a V-shaped structure consisting of two vertebrands.


In all automatic transmission technology, CVT is the most smooth, no one. Due to the continuity of the teeth of the variable speed, there is no so-called multi-stage fixed teeth ratio, there is no change in the CVT gearbox shift. Since there is no multi-stage fixed teeth ratio, the CVT transmission can work according to the working conditions to choose a relatively ideal adaptive tooth ratio, which is theoretically fuel-efficient gearbox. Its fuel economy is greatly better than the general AT speed. box. And the CVT gearbox is simple, high reliability, and is more convenient. However, the strength of the CVT gearbox drive is limited, and the loadable torque is extremely small, so the acceleration sensation will be relatively poor, speed up the meat, and the overtaking is weak. A performance vehicle with a hundred kilometers is less than 5 seconds, and the large displacement off-road vehicle will not consider the CVT gearbox. Simulated 7-speed CVT in Nissan (Parameter | Pictures), the 7-speed CVT, sleeper, and the climbing is bound to be weaker than other automatic transmission, which may also cause the gearbox under the use of vehicle violence. damage.

DCT (Double Clutch Transmission)

The DCT dual clutch speed is also a more mainstream automatic transmission. There are many car companies in use, such as the mass, Ford, Roewe, General, etc., China's brands also follow up research and development and mass production DCT transmission.


Double clutch gearboxes typically have two clutches connected to the two input shafts, shift and clutch operations are achieved by integrated electronic and hydraulic components. It is a popular saying that there are two clutches in this gearbox, one control 1, 3, 5 files, one control 2, 4, 6 files. When using a file, the second gear is ready, the same, so the shift time is greatly shortened. The advantage of the double clutch alternate is small, the oil is saved, and the shift is fast. Although the double clutch is so smooth, it has been smooth relative to the AT transmission, and its torque limit it can be loaded is larger than the CVT gearbox, and the power ratio transmitted to the wheel is also the largest. However, in a half-linking state, the dual-clutch transmission is prone to overheating, which is why the initial dry dual clutch gearbox fault is frequent. For example, when Volkswagen DSG initially entered China, there was a large-area gearbox overheating protection, in fact, the cause of the mass double clutch alternator on China's road conditions is not enough. In order to solve this problem, the simplest way is to adjust the degree of friction connection in a dry dual-clutch alternating speed box, but thereby also results in a dual-clutch gearbox in a low-speed low chassis. In addition, it is also a good idea to change the damp dual-clutch gearbox, but the cost is a big problem. At present, many car companies are also constantly improving their own DCT dual-clutch alternatives. I believe that the dual-clutch gearbox will make mature stability in the near future.