Patent ID: 7178654

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; and 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 hydraulic clutch actuation system operable for applying a clutch engagement force to said friction clutch assembly, said hydraulic clutch actuation system including an electric motor drivingly coupled to a first piston, said first piston being slidably positioned within a housing for supplying pressurized fluid to an accumulator, said pressurized fluid within said accumulator being in selective fluid communication with a second piston, wherein supply of said pressurized fluid to said second piston provides said clutch engagement force, said hydraulic clutch actuation system further including a controller, a pressure sensor operable to provide said controller a signal indicative of a fluid pressure within said pressure chamber, and a second pressure sensor operable to provide said controller a signal indicative of a pressure of fluid within said accumulator.