Research On Shift Control Strategy Of Automatic Transmission For Matching High-power Tractor

In the course of vehicle driving,the automatic gearbox can automatically change the transmission ratio of the gear train according to the current speed and throttle opening of the vehicle,and realizing automatic gear shift.Compared with manual gearboxes,automatic gearboxes do not require manual gear shift,which can reduce driver fatigue.At present,the research on automatic gear shift of multi-gear with high-power tractors in China is relatively few,and most of the production and application are still in the stage of manual transmission.In fact,a tractor with manual transmission needs a clutch and manual gear shift in the process of manual gear shift,which can cause the power of the tractor to be interrupted for a short time,and can lead to decrease in the working efficiency of the tractor.At the same time,the working characteristics of tractor engines are usually in low speed and high torque,but manual switching between different gear shifts will inevitably lead to shift frustration.The shift control strategy of multi-gear and automatic gear shift can greatly improve the tractor power and ensure the stability in operation.Therefore,it has important engineering application value to study and analyze the automatic shift control strategy of high-power tractor.The main content of this paper is to study the shift control law of high-power tractor,which under the premise of adopting hydraulic automatic gearbox as gear shifting mechanism,and finally get a reasonable shift control strategy.Based on the theory of automobile,the model of power source and transmission system of high-power tractor is established based on the Matlab/Simulink module.Based on the experimental data of high-power diesel engine bench,the torque characteristic curve of tractor engine,the main parameters of hydraulic torque converter,the speed ratio of gear train stages,Shift transfer critical value,the transmission load,brake torque and ground load coefficient are determined.In the Matlab/Simulink module,the tractor transmission subsystem(engine subsystem,hydraulic torque converter subsystem,torque conversion subsystem),GUI-controlled tractor throttle and brake modules,tractor complete machine moduleTractor,Tractor shift results display module and tractor overall power transmission system module are established.The shift transfer module is established in the Matlab/Stateflow module.Based on the complete machine dynamics model established in Matlab/Simulink/Satlow software,the control strategy of high-power tractor is simulated under different working conditions.Then based on the analysis of the simulation results of the whole machine,combined with the application of feedback control in automatic gear shift control,the conclusion is that in order to have high-quality dynamic gear-shifting characteristics of high-power tractor,the gear-shifting actuator must match the speed,throttle and gear-shifting time accurately,so as to achieve a stable and non-impact up-and-down gear process.This paper provides the theoretical basis and technical support for the localization of automatic gear shifting system of high power tractors.