Patent ID: 8187145

Claim:
Method for controlling a hydraulic line pressure of a hydraulic control system in an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and an electric machine adapted to selectively transmit mechanical power to an output member via selective application of a plurality of hydraulically-applied torque transfer clutches, said method comprising: monitoring a current output torque of said transmission; monitoring a requested output torque command; monitoring transmission of clutch reactive torque in each of said clutches; adjusting a minimum clutch torque capacity as a feed-forward control based upon said clutch reactive torques and comparing said requested output torque command to said current output torque; and controlling said hydraulic line pressure by modulating operation of said hydraulic control system based upon said minimum clutch torque capacity; wherein said current output torque is generated by providing mechanical power from said electric machine and selectively providing mechanical power from said engine.