A Study On Lock-up Rule And Slip Control Of 4AT Torque Converter

It is an innovation for automotive transmission technology that torque converter was put into used in automotive automatic transmission. Automatic transmission is helpful in starting the car smoothly and steadily, exchanging the level flatly, operating by hand much easier, also it makes driving more relaxed and facilitative. Since it has the advantages listed above, the use rate of automatic transmission has increased greatly in the whole world. However, the conventional torque converter transfers power by hydraulic, when the speed and the gear is very high, it cannot convert hydraulic transmission into mechanical transmission, just to satisfy comfort, so there is a disadvantage that is the efficiency of transmission is not good enough. Among the various studies of improving the transmission efficiency of torque converter, slip control technology of lock-up clutch has shown the special impact already. This technology can make torque converter operate more efficiently because a part of engine power is directly transferred by lock-up clutch with efficiency of approximate 100%, which is realized by the control of tiny slip rotation speed of lock-up clutch through adjusting the engaging pressure between two sides of the lock-up clutch within little structure change of the traditional torque converter provided with lock-up function.This paper analyzes the input and output characteristics of the united operation of engine and torque converter according to the experiment data of engine and the original features of torque converter; Work principle of automatic transmission clutch electro-hydraulic control system is presented general, lock-up clutch control system is analyzed mainly, also we study detail work process of lock-up clutch solenoid; We establish the shift rule of automatic transmission and the lock-up rule of torque converter at basis of it, also we analyze the simulation results of the torque converter lock-up control model; According to the relationship between power distribution ratio, the level of torque fluctuation of transmission and transmission efficiency, we analyze the output features of lock-up clutch slip and confirm the slip region and target slip speed, and we have established the mathematical model of slip control under the study of slip control system of lock-up clutch; Based on the Matlab/Simulink, we have established slip control model of lock-up clutch, we get experiment data of slip speed and engine speed through the experiment of torque converter slip control, and we calculate transmission efficiency from engine to the turbine and the transient fuel consumption; so we make a confirmation of better transmission efficiency of torque converter and better fuel economy of automobile.