Solenoid actuated variable pressure relief valve assembly for torque transfer assembly

A torque transfer assembly in a motor vehicle, said torque transfer assembly comprising:

• a ring gear assembly adapted to deliver an input drive torque;
• a differential assembly adapted to receive said input drive torque, said differential assembly being rotatable relative to said ring gear assembly;
• at least one output shaft drivingly connected to said differential assembly through a differential gear mechanism;
• a friction clutch pack for selectively delivering said input drive torque from said ring gear assembly to said differential assembly, said clutch pack comprising at least one inner friction plate coupled to rotate with said differential assembly and at least one outer friction plate coupled to rotate with said ring gear assembly;
• and
• a hydraulic clutch actuator for selectively frictionally loading said clutch pack, said actuator comprising:
• a hydraulic pump for generating a hydraulic pressure to frictionally load said clutch pack;
• and
• a variable pressure relief valve assembly to selectively control said friction clutch pack, said variable pressure relief valve assembly including a valve closure member, a valve seat complementary to said valve closure member, and a electro-magnetic actuator for engaging said valve closure member and urging thereof 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 electro-magnetic actuator,
• wherein said valve closure member is movable between a closed position when said valve closure member engages said valve seat and an open position when said valve closure member is axially spaced from said valve seat.