What is the structure of continuously variable transmission?

As the name implies, CVT is similar to automatic gearbox in operation, but the change of speed ratio is different from the stop process of automatic gearbox, but continuous, so the power transmission is continuous and smooth. In CVT transmission system, the traditional gear is replaced by a pair of pulleys and a steel belt. Each pulley is actually a V-shaped structure consisting of two conical disks. The engine shaft is connected with a small pulley, and the big pulley is driven by a steel belt. The mystery lies in this special pulley: the transmission pulley of CVT has a strange structure and is divided into two movable halves, which can be relatively close or separated. The conical disk can be tightened or opened under the hydraulic thrust, and the width of the V-shaped groove can be adjusted by extruding the steel chain. When the conical disk moves inward and tightens, the steel chain will move out of the center of the circle (centrifugal direction) under the extrusion of the conical disk, and vice versa. In this way, the diameter of the disc driven by the steel chain increases and the transmission ratio changes. What are the advantages of CVT gearbox? Because there is no transmission gear of general automatic gearbox, there will be no shifting process of automatic gearbox, and the sense of shifting frustration will disappear, so the power output of CVT gearbox is linear and very smooth in actual driving. Theoretically, the transmission system of CVT can have infinitely many gears, and it is easier to achieve the balance of transmission ratio, speed ratio, performance, fuel consumption and exhaust emission in the traditional transmission system. The mechanical efficiency and fuel economy of CVT transmission are much better than ordinary automatic transmission, second only to manual transmission, and the fuel economy is much better. "Anatomical diagram of CVT gearbox of Audi A6L" Since "CVT gearbox steel belt of Audi A6L" has so many advantages, why not let all cars adopt CVT gearbox? There are two factors: compared with the traditional automatic gearbox, its cost is slightly higher; And if the operation is improper, the probability of problems is higher. CVT gearbox itself also has its shortcomings, that is, the power that steel belt can bear is limited, but with the progress of science and technology, the problem of steel belt carrying capacity is being solved, and soon we can see that large displacement and high torque models will be equipped with CVT gearbox.