Simulation analysis of V-belt style continuously variable transmission with electro-hydraulic proportional control system

The early version of the mechanically controlled continuously variable transmission (CVT) with hydraulic servo system has been improved and electro-hydraulic proportional control system has been designed. By analyzing operating principle of electro-hydraulic proportional system, respective function of the electro-hydraulic proportional directional valve and electro-hydraulic proportional pressure valve in the system and running resistance of vehicle in all kinds of working conditions, a mathematical model using the method of linearization has been established. The mathematical model included two models. The first, electro-hydraulic proportional system model was obtained based on a hypothesis that the connection between V-belt and tape reel was inflexible, drive wheels oil cylinder and driven wheel oil cylinder were considered cavity without piston pole and cavity with piston pole in a: hydraulic cylinder and their effective area ratio was proximity two. The second, resistance model was established based on the relations among running resistance of vehicle, vehicle speed, rotational speed of engine, CVT ratio and hydraulic cylinder displacement. Thinking about the complexity of CVT transmission system, fuzzy controller has been designed. Simulation has been carried out based on the mathematical model and fuzzy controller. Simulating results show that the electro-hydraulic proportional system model is in accordance with the practicable working condition of CVT transmission system, which provides the foundation of the development of CVT control system.