Study On Slip Control Technology Of Hydraulic Torque Converter For Automatic Transmission

When the vehicle starts in the traditional way,the hydraulic torque converter is always in the condition of complete hydraulic transmission,which can make a smooth start but reduce the transmission efficiency of the system.If the hydraulic torque converter carries out slip control when the vehicle starts,the power of the engine can be transmitted in multiple ways so that one part of the power can be transmitted through the turbine while the other part of the power can be transmitted through the lock clutch.It can not only retain the ability of absorbing vibration and alleviating impact of the hydraulic torque converter but also enlarge the working range of the locking clutch,thus reducing the energy transfer loss of the torque converter,improving the transmission efficiency of the system and achieving the compromise in the starting performance and comfort.In view of the above problems,this paper takes the hydraulic torque converter with locking clutch as the research object,and studies the slip control of the hydraulic torque converter under the starting condition.The main research work is as follows:(1)Based on the test data,the characteristic curves of engine and hydraulic converter established and analyzed,and the simulation models of engine and hydraulic converter are established,the common working characteristics of the engine and the hydraulic torque converter under pure hydraulic and slip conditions are studied.(2)Introducing the function and structure of the hydraulic control system of the lock clutch of the hydraulic torque converter,and analyzing the working principle of the reversing valve and solenoid valve in the system emphatically.The transfer function of the hydraulic control system is derived by combining the dynamic balance equation and the flow continuity equation,and the mechanism simulation model of the hydraulic control system is established.(3)Analyzing the slip control principle of hydraulic torque converter,formulating the control strategy of starting slip of hydraulic torque converter,and introducing the important performance evaluation index of starting control.Then,taking into account the vibration impact of starting slip intervention and termination,designing the fuzzy controller of starting slip of hydraulic torque converter by using fuzzy control algorithm,and building the simulation model of starting slip of hydraulic torque converter based on MATLAB.The simulation results show that compared with the traditional complete hydraulic starting,the starting slip control strategy of the hydraulic torque converter developed in this paper can effectively improve the transmission efficiency of the system,reduce the vibration impact when the starting slip intervenes and terminates.(4)In order to verify the feasibility of the starting slip control strategy of the hydraulic torque converter developed in this paper,the bench test platform based on the cooperative unit was tested and verified.The experimental results show that the control strategy of starting slip of the hydraulic torque converter is feasible,and compared with the traditional complete hydraulic transmission,it can effectively improve the transmission efficiency of the system.