What's the difference between 4AT, 6AT and 8AT? Why can't China car companies build AT gearboxes?

According to the different working principles, there are four common forms of automobile automatic gearbox: AC and am, and each gearbox has its own loyal fans, among which At gearbox is the gearbox with the highest market penetration rate at present. After years of development, at gearbox has gone from the original 4AT6AT to the current 8AT highway, up to BMW and Mercedes-Benz, down to Honda and Toyota. At gearbox is also called Li Yan automatic gearbox, and the number in front represents the gear of automatic gearbox.

For example, 4AT means that the gearbox can simulate four gears. The bigger the number, the more gears there are, the more gears there are in the car, the more accurate the control of the transmission ratio, the smoother the shift of the car, and the better the transmission efficiency and fuel economy. Moreover, at gearbox can bear great torque, with excellent stability and extremely low failure rate. It only needs the owner to change the oil regularly, so the at gearbox is always unpopular. However, with the improvement of at gearbox level, the more gears, the finer the internal division of labor, the more parts needed, the larger the gearbox volume and the more manufacturing costs.

Usually, the complexity of the transmission control system will increase several times with each additional gear in the at gearbox. In the automobile industry, the technical potential of At gearbox is inclined. What is important is that with the patent protection of at technology, a very high technical barrier has been built. These patents almost formed an insurmountable obstacle to the later gearbox research and development enterprises. In China, it is not without car companies trying to develop gearboxes. In 2009, Geely acquired a gearbox company in Australia and produced its own brand of 6AT gearbox.

However, due to the weak technical strength, the performance and quality of Geely 6AT gearbox are always difficult to satisfy users. Therefore, although most car companies have their own R&D capabilities, when at speed change is needed, everyone can only look for German love.

Behind the development of at gearbox by Chinese enterprises, it also reflects a helpless fact that the adjustment of gearbox needs a lot of experience and support. Any at gearbox needs to get experience and data support from the previous generation products in the research and development process. These data are accumulated after hundreds of thousands or even millions of actual loads. For this gap, I believe it is difficult for China car companies to recover in a short time.