Patent ID: 7695400

Claim:
A method of controlling the speed of at least one driven accessory comprising: providing a drive motor adapted for driving said at least one driven accessory; wherein said at least one driven accessory is characterized by an optimal operating speed range; providing a torque-transmitting mechanism selectively engagable to operatively connect an engine with said at least one driven accessory; monitoring whether the torque-transmitting mechanism is in an engaged state or a disengaged state; monitoring speed of the engine; comparing monitored engine speed to a predetermined range of speeds from a predetermined minimum speed to a predetermined maximum speed, including the predetermined minimum and the predetermined maximum; wherein the predetermined minimum speed and the predetermined maximum speed are calculated based on the optimal operating speed range; and controlling power to said drive motor and engagement of the torque-transmitting mechanism such that said at least one driven accessory is driven by the engine if monitored engine speed is within the predetermined range and is driven by the drive motor if monitored engine speed is not within the predetermined range; wherein said controlling includes engaging the torque-transmitting mechanism so that said at least one driven accessory is driven by the engine if monitored engine speed is not less than the predetermined minimum speed and not greater than the predetermined maximum speed and the torque-transmitting mechanism is in the disengaged state; disengaging the torque-transmitting mechanism and controlling power to the motor so that said at least one driven accessory is driven by the motor at a speed within the optimal operating speed range if monitored engine speed is less than the predetermined minimum speed or greater than the predetermined maximum speed and the torque-transmitting mechanism is in the engaged state; and powering the motor so that said at least one driven accessory is driven by the motor at a speed within the optimal operating speed range if monitored engine speed is less than the predetermined minimum speed or greater than the predetermined maximum speed and the torque-transmitting mechanism is in the disengaged state.