Abstract: Coordinated engine control is an essential method to improve the shift quality. The relationship between the output torque fluctuation of upshifting and shift quality is analyzed. In order to reduce the output torque fluctuation, an output torque observer is designed based on the torque converter model, and then a torque based coordinated engine control strategy is proposed. Finally the experimental study is carried out on the test bench. The experimental results show that the torque response of the diesel engine with electronic unit pump can meet the requirement of coordinated control during the shifting process; and the torque based engine control strategy can make the output torque fluctuation reduced and shift quality improved apparently.

Key words: Automatic transmission, Diesel engine, Shift process, Torque based control, Torque observer