Hydraulic clutch control systems of power-shift transmission for a tractor
Three different types of hydraulic clutch control systems of the power-shift transmission for a tractor are presented in this study: conventional hydromechanical system, electronic control system with pressure reducing valve, and PWM control system with high-speed 3-way solenoid valves. First, conventional clutch pressure modulating system using mechanical linkage and accumulator was modeled and simulated. The results of simulation were compared with those of bench and real vehicle tests to validate the analytic model. The effect of various design and operation parameters such as oil temperature, size of accumulator and orifice diameter were analyzed to obtain optimal pressure modulation performance minimizing transmission shift shock. Second, clutch pressure control system using electrically proportioning pressure reducing valve was analyzed by simulation and experiments. It was revealed that the clutch pressure cannot be modulated to match the target value adjusted by the electric voltage to the pressure reducing valve, and that transmission quality can be deteriorated because of the elasticity of clutch friction material. Third, new clutch pressure control system using high speed on/off solenoid valves were developed to overcome the drawbacks of precedent systems in this study. Analytical model was established to estimate the proper coefficients of PID control which were implemented by PWM method. Experiments show that proposed PWM control scheme can be efficiently used for optimal pressure modulation for the hydraulic clutch of power-shift.
Power-shift transmission Hydraulic clutch Pressure modulation Electric pressure reducing valve PWM control
Jae-Cehon Lee Jae-Kyu Lee Dae-Cheol Kim Young-Sun Kang
Faculty of Automotive and Mechanical Engineering/ Keimyung University, Daegu/ S. Korea Central R&D Center/ Tongyang Moolsan Co. LTD, Gongju, Choongnam/ S. Korea
国际会议
杭州
英文
307-311
2009-04-08（万方平台首次上网日期，不代表论文的发表时间）