Abstract: In order to take into account the requirements of both jerk and slipping work of torque converter in lock-up process, the vehicle dynamics model in torque converter lock-up process is set up, with the formulae of jerk, slip time and slipping work in lock-up process derived. Then taking a heavy-duty vehicle as an example, a simulation is conducted to obtain the jerk curve in a lock-up process with engine running in a constant deceleration condition. The results show that the jerk is much smaller than the standard limits and it is found by calculation and analysis that in the lock-up process with the engine decelerating with a constant rate, the reasonable values of clutch pressure coefficient are in a range of 1.05 and 1.2 with a slipping time of around 1s. Finally according to the results of simulation, a control strategy for lock-up process is put forward based on the target trajectory of engine speed, with its feasibility verified by real vehicle test. This study provides an effective strategy for clutch engagement control with concurrently considering the requirements of both jerk and slipping work

Key words: torque converter, engine speed, lock-up control, jerk, slipping work