Dynamic analysis and control strategy of wet clutches during torque phase of gear shift

Abstract

Control over the clutch during gear shift is the key technique in automatic transmission shift control and this control largely decides the shift quality. The engagement of the on-coming clutch and the disengagement of the off-going clutch should be controlled synchronously and accurately to achieve a smooth shift. Optimal control of clutch torque exchange phase is required to achieve this synchronous and accurate control. Shift quality can be easily influenced with inappropriate control parameters because of the many factors that affect the torque phase, as well as the use of closed-loop control. In this study, a dynamic model of frictional clutch with electro-hydraulic shift control is built. On the basis of the study of the influence of clutch-related parameters, an optimal control model is proposed with the closed-loop control together with an adaptive control method based on micro-slip clutch control. This control method can continually self-adjust control parameters to prevent shock, improve control precision and effectively reduce the calibration work after. Test result shows that this closed loop with adaptive method ensures consistently good shift quality.