What is the principle of a continuously variable transmission?
2 Answers
The principle of a continuously variable transmission is: the steel belt transmits the force from the driving pulley assembly to the driven pulley assembly. The torque is then transmitted to the internal shaft via a single planetary gear system with multi-plate clutches. Through the gear intermediate shaft, the torque is transmitted to the differential, which evenly distributes the driving force to the axles. A continuously variable transmission allows the gear ratio to vary continuously within a certain range. It consists of a fixed pulley, a movable pulley, a steel belt, a planetary gear assembly, multi-plate clutches, an electro-hydraulic control unit, and an electronic control unit. Continuously variable transmissions are categorized into: hydro-mechanical continuously variable transmissions and metal belt-type continuously variable transmissions.
I understand the principle of the continuously variable transmission (CVT), which essentially relies on two variable pulleys and a sturdy belt to change speeds. Imagine the pulleys as two cones that can expand or shrink in diameter. When the driver presses the accelerator, the system automatically adjusts the size ratio of the pulleys, with the belt transmitting power in between. This allows the engine to continuously vary its speed without the traditional gear-shifting jerk. The driving experience is exceptionally smooth, with acceleration as seamless as gliding on ice, because the engine always stays within the optimal RPM range, which also helps reduce fuel consumption. However, CVTs are prone to issues like belt wear or slippage, and repairs can be expensive, so I need to weigh comfort against durability when choosing a car. From a physics perspective, it avoids the impact of fixed gear ratios, delivering power more directly, but the design requires precise control of pulley pressure to prevent overheating. In short, its clever principle makes driving more comfortable and efficient.
