Multi-state control strategy of starting for a wet friction clutch via a fuzzy logic algorithm

Wet multi-plate friction clutches are used in automotive drivelines to transfer torque, change gears, and prevent motion by locking-up components in the transmission. The control strategy of starting is a crucial technology for the application of a wet multi-plate friction clutch in the automotive industry. In this paper, a multi-state fuzzy control strategy for starting is presented and applied to a continuously variably transmission (CVT) powertrain for the validation of this strategy. The operation of the clutch was divided into four states: parking, starting, riding and emergency. The starting state was investigated in detail. A fuzzy algorithm was employed to control the pressure of the hydraulic cylinder acting on the clutch. A distinguishing feature is that the pressure does not increase but decreases to implement smooth starting during the initial period of starting. The rapid-control prototype (RCP) of the wet friction clutch was developed to validate the new control strategy onboard a test vehicle. Based on the experimental results, the multi-state control strategy for a wet friction clutch is a viable candidate for engineering applications.