Dynamic modeling and optimal design of the speed ratio control valve in CVT

Properties of the speed ratio control valve used in continuously variable transmission (CVT) effect the performances of the whole electro-hydraulic control system. A method for dynamic performance optimization of CVT speed ratio control valve based on genetic algorithm (GA) is presented in this paper. The structure and basic working principle of the valve are analyzed firstly, and then a dynamic model is set up by means of mechanism analysis. For the purpose of checking the validity of the modeling method, a prototype workpiece of the valve is manufactured for comparison test, and its simulation result follows the experimental result quite well. An associated performance index is founded considering the response time, overshoot and saving energy, and then four structural parameters are selected to adjust for deriving the optimal associated performance index. The optimization problem is solved by the classic genetic algorithm with necessary constraints. Finally, the properties of the optimized valve are compared with those of the prototype workpiece, and the results prove that the dynamic performance indices of the optimized valve are much better than those of the prototype workpiece.