Patent ID: 7083030

Claim:
A power transmission device comprising: a rotary input member adapted to receive drive torque from a source of torque; a rotary output member adapted to provide drive torque to an output device; a torque transfer mechanism operable for transferring drive torque from said input member to said output member, said torque transfer mechanism including a friction clutch assembly operably disposed between said input member and said output member and a magnetorheological clutch actuator operable for applying a clutch engagement force to said friction clutch assembly, said magnetorheological clutch actuator including a first thrust cam fixed for rotation with and axial movement relative to said input member and having a first cam surface, a second thrust cam having a second cam surface, a chamber formed between said first and second thrust cams in which said first and second cam surfaces are disposed and which is filled with magnetorheological fluid, and an electromagnetic coil arranged to vary the viscosity of the fluid in said chamber in response to electric control signals; and a controller for generating said electric control signals.