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A wedge clutch with a wedge ramp transfers the tangential force to an axial force. It has unique features of self-reinforcement and small actuation force, and can be packaged into tight spaces. This wedge clutch can be developed to apply to an automatic transmission (AT) or a hybrid transmission. This paper focuses on the simulation of one wedge clutch in AT during shifting. A mathematical formula is given to describe the self-reinforcement principle of the wedge. The dynamic model of a motor actuated wedge clutch during shifting is built to simulate and develop the control algorithm. The model is implemented in Matlab/Simulink, which includes a DC motor model, a dynamic model of the wedge mechanism and clutch pack, and a driveline model of AT which can simulate a gear shift process. The key characteristics such as variation of normal pressure, response time and energy consumption are evaluated, and the results show a favorable comparison with the traditional hydraulic clutch.

Rotating clutches play an important role in automatic transmissions (AT), dual-clutch transmissions (DCT) and hybrid transmissions. It is very important to continually improve the transmission systems in the areas such as simplifying actuator designs, reducing cost and increasing controllability. A new concept of electrical motor driven actuation using a wedge mechanism, a wedge clutch, demonstrates potential benefits. This wedge clutch has the characteristics of good mechanical advantage, self-reinforcement, and faster and more precise controllability using electrical motor. In this paper, a new rotating wedge clutch is proposed. It presents a challenge since the motor actuator has to be stationary while the clutch piston is rotating. A new mechanism to connect the motor to the wedge piston, including dual-plane bearings and two mechanical ramp linkages, is studied. The design and verification of the physical structure of the actuator are discussed in detail in the paper.