Research And Simulation On Shift Schedule In Automatic Transmission

In total vehicle power-transmission system, transmission occupies an importantposition, which combines with automatic transmission technology make a bigenhancement of vehicles control ability, stability and reduce operation intensity ofdrivers.Hydraulic automatic transmission not only can be equipped with various typesof vehicles but also can match all kinds of engines, thus, the application of hydraulicautomatic transmission is very extensive.Shift schedule is critical to automatictransmission control system, and it has an important influence on the performance ofvehicles.In this paper, the study of hydraulic automatic transmission is mainlycomposed of the following aspects:This paper summarized the classification, advantages and development status ofautomatic transmission, concluded the hydraulic automatic transmission system’sresearch status.The working principle of hydraulic torque converter which is animportant part of hydraulic automatic transmission was analysed.According to theoriginal data of hydraulic torque converter, the characteristic curve of hydraulic torqueconverter was fitted, and in accordance with the characteristic curve, the features ofhydraulic torque converter can be observed intuitively and analysed.It is engine and hydraulic torque converter matching problem that is the basis ofresearching shift schedule, so the problem is worth further researching.The matchingmathematical model was established and optimized by particle swarm optimizationalgorithm and genetic algorithm.The optimization target which is effective diameter ofhydraulic torque converter is optimized successfully, as a result both dynamicperformance and fuel economy performance of the vehicle are improved.Theclassification of shift schedule according to the different control parameters wasreviewed.The calcuation method of best power performance shift schedule and the bestfuel economy shift schedule were analysed.In the MATLAB environment, the shiftpoints are calculated and the best power performance curve is made.And the formulasfor calculating the optimum fuel economy shift schedule are deduced.In the MATLAB/Simulink environment, vehicle power transmission system and its simulation model of each subsystem were built.The simulation was carried out underthe given condition and dynamic shift schedule, the simulation results meet actualsituation and verify the feasibility of the scheme.