The mainstream transmissions currently used in cars include AT transmissions, DCT (or DSG) transmissions and CVT transmissions. Among them, AT gearboxes are more common, DCT (or DSG) gearboxes are currently mainly used by German cars or independent brands, and CVT gearboxes are the favorite of Japanese cars. Of course, some independent brands also use them.
picture
The two more famous manufacturers of AT gearboxes are Japan's Aisin and ZF. This also reflects from the side that Japan does not lack AT gearbox technology. However, in comparison, Japanese cars are still mainly equipped with CVT gearboxes. The reason is also closely related to Japan's development philosophy.
picture
Japanese cars generally have lower fuel consumption. There are many factors that affect a car's fuel consumption. In addition to the engine and gearbox, there are also main reduction ratio, vehicle weight, drag coefficient, tires, etc. Among them, the engine and gearbox are the two most important factors. So how much impact does the CVT gearbox have on fuel consumption?
CVT gearbox, also known as continuously variable gearbox, has a relatively simple structure and mainly includes basic components such as a driving wheel set, a driven wheel set, a metal belt and a hydraulic pump. The metal belt is composed of two bunches of metal rings and hundreds of metal sheets. Both the driving pulley set and the driven pulley set are composed of a movable disc and a fixed disc. The pulley on the side close to the cylinder can slide on the shaft, while the other side is fixed.
Both the movable plate and the fixed plate have conical structures, and their conical surfaces form V-shaped grooves to mesh with the V-shaped metal transmission belt. The power output from the engine output shaft is first transmitted to the driving wheels of the CVT, then transmitted to the driven wheels through the V-shaped transmission belt, and finally transmitted to the wheels through the reducer and differential to drive the car.
The working process of the CVT transmission is to change the working radius of the engagement between the driving wheel, the driven wheel cone surface and the V-shaped transmission belt through the axial movement of the movable disc of the driving wheel and the driven wheel, thereby changing the transmission ratio. The axial movement of the movable disk is achieved by the driver adjusting the hydraulic pump cylinder pressure of the driving wheel and driven wheel through the control system as needed. Since the working radius of the driving wheel and the driven wheel can be continuously adjusted, stepless speed change is achieved.
Through the entire shifting process of the CVT transmission, it is not difficult to find several advantages:
The first is fuel saving. Because CVT can achieve continuously variable transmission within a fairly wide range, it can achieve the best match between the transmission system and the engine operating conditions and improve the fuel economy of the entire vehicle.
The second is motivation. Due to the continuously variable transmission characteristics of CVT, it can obtain the transmission ratio with the largest backup power, so its power is significantly better than that of MT and AT gearboxes.
Then there are emissions. The CVT's wide speed ratio working range enables the engine to work in optimal working conditions, thereby improving the combustion process and reducing exhaust emissions.
Finally there is the cost. The CVT system has a simple structure and fewer parts than AT. Once car manufacturers start mass production, the cost of CVT will be smaller than AT.
