Influence oil temperature and pressure on clutch control for clutch actuator system

The demand for comfort and performance in vehicles requires more accuracy in clutch control of automatic transmissions. For the widely spread automatic transmission the main influence are caused by the fluid temperature as well as with different operation pressures besides control algorithm. It requires adequate experience and proper understanding to interpret the pressure response results in the presence of fluid temperature and operating pressure variations. Proper analysis of the pressure test result is only possible with an understanding of the physical behavior of the clutch actuator system in response to fluid temperature and operating pressure. A clutch actuator model, which describes the pressure response in the clutch chamber behavior, has been investigated in this paper. The values of the parameters of the fluid properties have been analysed from manufacture data. A differentiation has been observed with several fluid temperature and operating pressure that can be used as additional information for better interpretation of the clutch chamber pressure response results. This paper thus reports a detailed study on the effects of the fluid temperature and operating pressure on pressure response of a clutch actuator under controlled conditions. Some simulation results presented to demonstrate the influence of fluid temperature and operating pressure that may be introduced in clutch control analysis unless temperature and pressure variations effects are taken into consideration.