Research On Lock-up Point Optimum And Lock-up Dynamic Characteristic Of Torque Converter Used In Tracked Vehicle

Torque converter is widely applied to tracked vehicle.However due to its inefficiency at high speed ratio,lock-up torque converter is used.Lock-up point and lock-up hydraulic pressure characteristics influence the process of locking up largely.In this paper,the lock-up point of torque converter was optimized,the hydraulic pressure model of lock-up control was established,and simulation of lock-up process was conduced.The specific contents are as follows:Firstly,the matching of engine and torque converter was researched,the input and output properties were studied,and the matching results based on evaluation indicators were analyzed.The results testified the rationality of the matching.Based on the matching analysis,different methods of making lock-up point in torque converter were researched.Study the optimal value of torque ratio that the torque converter output before and after locking up,the optimal value of inertial energy ratio before and after locking up,and establish the target function using goal programming method between the two optimal values.The results of optimization show that the speed difference and torque difference of engine decreased obviously after lock-up point optimized.In study of the lock-up dynamic characteristic of torque converter,the mathematic model of lock-up process was established.Based on the analysis of influence factors such as hydraulic pressure for lock-up process,the lock-up control hydraulic pressure model was established.The Matlab/Simulink was applied in simulation of lock-up process.The results of simulation show that the optimization of lock-up point can largely reduce the attack to engine and the hydraulic pressure model can lower the friction power.