Clutch fill control of a heavy-duty automatic transmission

Abstract

In this paper, a clutch filling phase control for gearshifts on wet clutch transmissions is developed. In a clutch-to-clutch shift of an automatic transmission, in order to achieving a smooth start to the shift process, the commanded fill pressure and the commanded fill time are critical. The overfill and underfill problems are often raised due to the calculating errors in these two parameters. To address these challenges, a new fill phase control strategy is proposed based on the system analysis. The electro-hydraulic actuator system is analysed and modeled, and the control parameters is optimized according to the variation of the oil temperature and engine speed. The designed strategy is validated by a simulation work. The results demonstrated that the proposed control strategy and the parameters modified method can transit the shift process from the fill phase into the torque phase effectively.