| Because of the complex and severe operating environment,engineering vehicle needs tomanipulate the shiftfrequently,which usually leads to a low efficiency when operating the shiftsystem.Automatic gearshift technology can improve vehicle handling in the application of engineering vehicles and can improve operational efficiency.In addition,thecontrol technology of shift process also affects the vehicle's smoothness and service of transmission system parts.Therefore,it is of great significance to research electronic and hydraulic system of off-road vehicle transmission.The paper is based on the provincial projects "Simulation of Transmission Control Technology for off-road Vehicles",taking the shift law and the shift quality control as the research focus,optimizing the electro-hydraulic shift control system of the engineering vehicle transmission.The paper puts forward to the automatic combination strategy targetedly,and controls oil pressure to achieve the clutch of the soft combination,and eventually concluded these main research points:(1)This paper determines research routes by analyzing the structure,principles and electro-hydraulic shift system of the off-road vehicle power shift transmission.(2)Based on the AMESim software,the hydraulic model of the hydraulic system of the engineering vehicle is established and the simulation test is carried out to verify the rationality of the model and prepare for the control system.(3)Studying the current engineering vehicle shift strategy,aiming at the problem of low efficiency of the transmission system in the process of engineering vehicle operation,a reasonable shift rule is established based on the improvement of the torque converter transmission efficiency,and the locking point of the inefficient zone torque converter on the right side of the gear are deduced.The fuzzy shift controller is realized by MATLAB,combined with the mechanical and hydraulic model of the vehicle transmission system,which verified that the shift law can be changed by the timely transmission and the torque converter is locked to keep the converter working in the efficient range.(4)Vehicle shift quality evaluation indicators is analyzed that determines the relationship between clutch action and the quality of the shift.Through the transmission shift hydraulic test,the clutch hydraulic control deficiencies is found.The dynamic model of the shift process is established,and the influencing factors of the shift impact are deduced.The clutch hydraulic control strategy is proposed,and the clutch process of the clutch is controlled in stages and optimized by PID control in the buffer boost stage.Simulink software is used to establish the control model,combining with the drive system model,the simulation of the gearshift process is carried out to verify that the control strategy can ensure that the engineering vehicle has good gear quality. |
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