Integrated control strategy of tractor hydromechanical continuously variable transmission

Abstract

Given the transmission efficiency fluctuation and response lag problem of hydromechanical continuous variable transmission combined with the complex and variable working environment of a tractor, an integrated control strategy of engine throttle compensation–hydromechanical continuous variable transmission speed regulation is adopted for dual-flow transmission control. On the basis of the estimation of working resistance, a fuzzy algorithm is used to design the throttle compensation law. Considering the maximum driving power of a tractor as the target of variable speed control, an hydromechanical continuous variable transmission efficiency model is established, and the control law of an hydromechanical continuous variable transmission displacement ratio with the maximum driving power of the tractor under any working condition is determined. On the basis of the wavelet neural network proportional–integral–derivative algorithm, the control law of the hydromechanical continuous variable transmission speed regulation is designed, and the parameters of proportional–integral–derivative control are corrected in real time during the control process. Based on MATLAB/Simulink modelling and simulation and the real vehicle verification test, results showed that the influence of hydromechanical continuous variable transmission efficiency fluctuation on the driving power of the entire vehicle, the response lag of the pump-controlled motor system, and the effect of the leakage on the variable speed control and the fluctuation of the working resistance are solved by studying the hydromechanical continuous variable transmission variable speed transmission control strategy. This strategy improves the stability of the tractor speed and ensured the quality of the work, thereby improving the ability of the tractor to adapt to complex working environments.