Hydraulic Servo Cvt Design

The hydraulic servo-control continuously variable transmission (CVT) studied in this paper is a new hydraulic CVT with hydraulic servo-control system on the basis of the original hydraulic CVT. Hydraulic servo control system replaces the original mechanical adjustment device. Transmission automatically adjusts hydraulic motor's speed to maintain it stability. It will not change in the case of any load fluctuation and the remote control can be achieved, the hydraulic servo-control CVT can meet the requirements of machinery automation.This paper firstly describes the hydraulic CVT working principle and analyzes the original control methods of variable pump. On the basis of the above analysis, this paper determines the overall program of hydraulic servo-control system and studies hydraulic control valves and the valve-control hydraulic cylinder system in the hydraulic servo-control system. Meanwhile, it identifies the main parameters of the main components.Secondly, this paper establishes mathematic model of the valve-control hydraulic cylinder system and determines parameters of the control engineering-describing function. The control engineering-describing functions of the system are simplified and this paper gets the simple and visible system state-equation. The stability of the system is also analyzed.Finally, based on the mathematical model, this paper makes simulation of the mechanic and hydraulic servo-control system by using the SIMULINK tools in MATLAB. Some performance parameters are optimized and more suitable system's performance parameters are obtained.