Patent ID: 7448482
Filing Date: 2008-11-11
Classification: F16D,F16H

Abstract:
1. A torque-coupling assembly comprising: a rotatable torque-coupling case; at least one output shaft drivingly operatively connected to said torque-coupling case; a friction clutch assembly for selectively engaging and disengaging said torque-coupling case and said at least one output shaft; a hydraulic pump for generating a hydraulic fluid pressure to frictionally load said clutch assembly; a variable pressure-relief valve assembly to selectively control said friction clutch assembly, said variable pressure-relief valve assembly including a valve closure member, a valve seat complementary to said valve closure member, and an electro-magnetic actuator for engaging said valve closure member and generating a variable axial electro-magnetic force urging said valve closure member against said valve seat so as to selectively vary a release pressure of said pressure-relief valve assembly based on a magnitude of an electric current supplied to said etectro-magnetic actuator; said electro-magnetic actuator including an eleetro-magnetic coil assembly and an armature disposed radially inwardly of said electro-magnetic coil assembly and axially movable relative thereto; a plenum passage provided adjacent to a radially inner peripheral surface of said armature for providing fluid communication through said electro-magnetic actuator; and an annular bushing disposed within an annular bore of said armature and rotatably supporting said electro-magnetic actuator to said torque-coupling case so that said plenum passage is formed between said armature and said bushing.