Study On Modeling, Simulation, Matching And Control Strategy Of Vehicle With Metal V-Belt Type Continuously Variable Transmission System

Continuously variable transmission (CVT) is the ideal transmission for automobile, it is also one of the most important research items of researchers and automobile companies all over the world. Study on matching and control strategy of metal pushing V-belt continuously variable transmission of automobile has important theoretical and engineering value. Theoretical and experiment researches of transmission mechanism and control strategy of the CVT have been carried out under the project (59835160) financed by National Natural Science Foundation which includes follow content:1)The kinematic relation of the metal pushing V-belt type transmission is analyzed. The relation among oil pressure of pulley cylinder, transmission ratio and input torque under load condition is studied. Optimal design method for metal pushing V-belt type continuously variable transmission is put forward.2)Based on the engine experiment, torque and oil consumption model of engine are established by method of spline interpolation. The optimum economy and performance curves are put forward. Speed ratio control model of CVT is established which can realize the control of engine operation along target line. The economy and performance characteristics of LIYANG car equipped with CVT and MT (manual transmission) are studied respectively and compared. 3)Based on experimental analysis, the relation among the speed ratio changing rate, oil pressure of driving and driven pulley cylinders, driving pulley input speed and torque, metal belt speed ratio has been studied. Model for getting the ratio changing rate is put forward, and practical equation giving the ratio changing rate is obtained by experiments. 4)By the bond graph theory, a bond graph model is established and the state-space equations of drive system of the CVT car are derived. The effect of the profile of membership function and the defuzzification algorithm on the capacity of fuzzy controller is studied systematical, and a practical self-adaptive fuzzy controller is designed. A continuously variable transmission test bench is built. An autocontrolling software about Continuously variable transmission system is developed, the data of engine throttle opening, speed ratio of CVT and load can be gathered in test bench and the system can be controlled. 5)From the viewpoint of synthetic fuzzy control, expert control and graded control, a practical control strategy and controller for CVT vehicle standing start is put forward. Base on experiment of torque converter, a mathematics model of torque converter is established and control strategy for cooperating torque converter with CVT is put forward. By analyzing the engine driving torque characteristics and the transmission inertia torque while speed ratio is changed under transient condition, a new synthetic control algorithm is developed which can approach engine target torque by compensating engine output torque with transmission system inertia torque. In summary, the mechanism of metal push belt continuously variable transmission is studied. The engine and speed ratio control models are established, and the matching strategy of CVT vehicle is studied. The synthetic control algorithm is put forward which has been proved by simulation and experiment, the results of theoretical analysis and experiment are coherent. The research results provide the theory analysis and design method for CVT vehicle development.