Patent ID: 8083041
Filing Date: 2011-12-27
Classification: B60K,F16D,Y10T

Abstract:
1. A power transmission device comprising: a rotatable input member; a rotatable output member; a friction clutch selectively transferring torque between the input member and the output member; and an actuator providing an actuation force to the friction clutch, the actuator including an electric motor coupled to a pump, the pump having an outlet supplying pressurized fluid to a piston positioned within a closed volume, the piston acting on the friction clutch to generate a predetermined torque; a valve positioned in series between the pump outlet and the piston, the valve being moveable between a first position allowing fluid communication between the pump outlet and the piston and a second position where pressurized fluid acting on the piston is trapped between the piston and the valve to maintain the predetermined torque output of the friction clutch without continued energization of the electric motor; and a controller to determine whether the friction clutch is to be operated in a locked mode for a predetermined amount of time greater than a minimum threshold, the controller signaling the valve to move to the second position to place the friction clutch in the locked mode.