Research On Slip Control Of Lock-up Clutch In Torque Converter

The application of torque converter in automatic transmission means an essential improvement of transmission technology to vehicle. The automobile with automatic transmission has smooth starting, gearshifting and convenient operation. Accordingly, the amount of cars with AT has greatly increased all over the world. However, low transmission efficiency slows down the forward pace of automatic transmission. Among those measures for higher transmission efficiency, slip control of lock-up clutch shows its original significance. 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.According to the experimental data of engine and torque converter, the input and output characteristics of the united operation of engine and torque is investigated. The lock-up rule of LingYang 3AT of Chongqing Changan-Suzuki Automobile Inc. is made based on the lock-up theory of lock-up clutch. The lock-up clutch slip output characteristics is analyzed and lock-up region and slip rotation speed is set down according to the balance between transmission efficiency and transfer level of engine torque vibration. Hydraulic control cycle is framed based on the study of slip control system. On the basis of established model of slip control, the slip control simulation of slip speed at different slip speed is respectively performed with Simulink of Matlab, and also the efficiency of the transmission from engine to turbine is calculated under the aforementioned slip speed. Calculation of instantaneous fuel consumption of engine at the two aforesaid slip speed is carried out. Simulation model of integrated automatic transmission control is established, and ten-mode cycle simulation is carried through. The result indicates better transmission efficiency with the slip control of lock-up clutch than pure hydraulic transmission.