| Electro-hydraulic proportional control system is the one of the key components ofautomatic transmission, the analysis of its characteristics is the premise to realize shiftquality control, and the precise clutch pressure control of the system is a key link in theprocess of optimization control strategy. Thus, a clutch pressure control system thatachieved the precise control of clutch pressure under various operating conditions wasdesigned after the analysis of the characteristics and requirements of the electrohydraulicproportional control system for a integrated hydraulic mechanical transmission of thetracked vehicle.The electronic control unit and the hydraulic control module of the electro-hydraulicproportional control system are introduced, and the transmission flow of the control signalis analyzed. The steady-state and dynamic characteristics of the key institutions includingthe proportional electromagnetic valve, regulating valve, piston and oil cavity of the clutchare described trough the tests, and taking above institutions as a whole organization shiftcontrol mechanism, and its output characteristic is analyzed by testing. And then, theinfluence of the external factors such as the oil temperature, driving voltage and oil pumpflow on the output characteristics and the control parameters such as PWM controlfrequency, flutter signal are studied through tests, it provides effective reference of the fdemand analysis or thesubsequent pressure control system.The ideal clutch pressure trajectory curve is obtained when the clutch pressure controlsystem’s demand analysis combined with the dynamics analysis of the transmission systemand the characteristics analysis of the electro-hydraulic proportional control system wascarried out on, and the feedforward-feedback compound control system consist of theinverse mapping arithmetic, feedforward control, flutter signal control, PI control based oncurrent and PID closed-loop control based on pressure is designed, and the optimal settingof the control parameters are obrained respectively through the multi-dimensionalinterpolation method, quasi-newton method and gradient iteration self-learning algorithm.According to the design method of the control system, the hardware design andsoftware design of the controller are completed. After the control parameters of the control system are set on the test platform, the system performence is proved through thecharacteristic tests of the electro-hydraulic proportional control system. Through a givenclutch pressure trajectory curve, the clutch pressure tracking control experiment are carriedout on the test platform, and the results show that the designed clutch pressure controlsystem can effectively improve the accuracy and the robustness of the clutch pressuretracking control. |
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