Research On Shift Actuator Of Tractor Automatic Mechanical Transmission

The tractor gearbox is a key part of the tractor power transmission which has animportant influence on the tractor’s dynamic property, fuel economy and efficiency.With the developing of automatic transmission theory and which is widely used onvehicles, the demand to improve performance of tractors is increasing gradually. Manyfamous tractor companies adopt automatic transmission technology on tractors in theworld. But most of tractors use traditional manual mechanical transmissions in China,which results in shift operation frequently, shift difficulties, easy to make the driverfatigue. To apply automated mechanical transmission (AMT) on tractors cansignificantly improve maneuverability, reduce driver’s labor intensity, improveoperation efficiency and has bright application prospects in the tractor field.Based on the tractor automatic transmission theory, the structure principle ofAMT shifting actuator is analysed. Combined with the design requirements of shiftingactuator from tractor transmission, tractor AMT shifting actuator is designed andcalculated. The three-dimensional model of shifting actuator is established and virtualassembly is finished. Dynamic analysis of the shifting process is finished. By usingpower bond graph theory, the mathematical model of shifting actuator hydraulicsystem is established and the equation of state is derived. With dynamic analysis, theinfluence of parameters on the dynamic characteristics is got. By using the software ofAMESim, the characteristics of high-speed switching valve and the influences ofhydraulic oil viscosity, parameter of oil pipeline on dynamic characteristics are studied.Based on the theory of fuzzy control and closed-loop control, fuzzy controller ofshifting hydraulic cylinder output displacement is designed and the precise control ofshifting actuators displacement is finished. According to the characteristics of tractortransmission, the models of engine, transmission, power shift synchronizer, thehydraulic actuator control system and vehicle transmission system are established. Theinfluences on shift quality of the hydraulic shifting actuator are analysed by using MATLAB/SIMULINK and AMESim to finish co-simulation.