Research On Starting Locking Slip Control Technology Of Hydraulic Torque Converter In Uphill Condition

The torque converter uses pure hydraulic transmission to transmit engine power,and part of the engine power will be converted into heat energy and lost.The lock-up slip control of the torque converter turns the hydraulic transmission into a mechanical transmission,reducing energy loss.However,for starting uphill and other working conditions,if the flat ground lock slip control is used,it will cause the engine torque to fluctuate due to the drastic load change,resulting in vehicle vibration and shock.Aiming at this problem,the vehicle quality and road gradient angle are estimated in real time,based on which the hydraulic torque converter lock-up slip model is formulated,and the lock-up slip control performance is optimized through the double-layer fuzzy control algorithm.Specific work content includes:(1)First,without affecting the problem analysis,the vehicle model is simplified into three major subsystems: engine,lock-up clutch,and vehicle load,and the theoretical model of lock-up clutch power transmission is derived.Secondly,aiming at the problem of locking slip accuracy control and hydraulic oil cooling,analyze and improve the existing hydraulic control system and derive related control theory models.Finally,a theoretical model of the evaluation index of lock-up slip is derived.(2)Based on vehicle dynamics,derive the theoretical model of vehicle quality and road gradient angle estimation,use the deviation compensation recursive least squares algorithm()to estimate them in real time,and establish related models.Secondly,it is used to provide vehicle motion parameters for estimation—vehicle acceleration,driving force,speed,and simulated road gradient angle used to verify the estimation effect,and the quality of the whole vehicle.Finally,the co-simulation model is used to verify the accuracy of the estimation of the vehicle quality and the road slope angle,and the results show that the estimation effect is better.(3)In order to improve the self-adaptability of the lock-up slip control,a double-layer fuzzy controller for the lock-up slip is designed.The first layer of fuzzy input is the throttle opening and its rate of change,and the output is the lock slip time.The second level of fuzzy input is the error of the target engagement force and actual engagement force of the lockup clutch considering the lockup slip time and the error rate of change.The fuzzy output is the change value of the control parameter to update the parameter of the controller.Secondly,the scope of the lock-up slip control is preliminarily determined,and the lockup slip-related power transmission model derived from the previous theory is established based on Simulink.Finally,a joint simulation model of lock-up slip for uphill start is established.The simulation results show that as the slope angle increases,the lock slip time is relatively prolonged,the pressure change rate decreases,the impact degree gradually decreases,and the sliding friction work gradually increases.(4)The road experiments with different slope angles were carried out in the cooperative unit.The test results and the simulation results have a certain gap.This is because: 1.The time lag of the hydraulic control system;2.The simplification of the lockup slip hydraulic control model.However,the change trend is consistent,which can preliminarily prove the effectiveness of the lock-up slip control model for uphill start.