Design And Test On Controller Of Hydro-mechanical Continuously Variable Transmission

Hydro-mechanical variable transmission is a dual power flow transmission compounded by hydraulic transmission and mechanical transmission, and has the characteristics of high efficiency and stepless speed variation. There is a good application prospect in heavy vehicle. Controller is the key part of hydro-mechanical variable transmission. And the development of the controller is the basis for researches in its dynamic characteristics and control strategy.Based on the arithmetic of a two-range hydro-mechanical variable transmission, this paper carried out the design of hardware and software of the controller, formulated the strategy of speed control in range and shift, and verified parts of the function. The main research contents are as follows:(1)Determined the speed regulation scheme based on analysis of composition, working principle and the ratio characteristics of hydro-mechanical variable transmission controller.(2)Designed the hardware circuit of the hydraulic mechanical transmission controller, including the selection of microprocessor and peripheral circuit, switch signal acquisition circuit, analog signal acquisition circuit, pulse signal acquisition circuit, shift solenoid valve drive circuit, electro-hydraulic buffering valve drive circuit, variable displacement pump drive circuit and communication circuit.(3)Formulated the control strategy of Hydro-mechanical variable transmission, including speed control strategy and shift strategy; completed the control program written using Code Warrior programming software, including vehicle state collection program; previous speed control program; the range changeover control program, clutch/brake oil pressure adjustment program, and the main program.(4)Carried out the verification of part function of controller, including signal acquisition; clutch/brake oil pressure adjustment procedure ect. The results showed that the hydro-mechanical variable transmission controller designed in this paper basically meet the control requirements.