Patent ID: 7416510

Claim:
A method of controlling a vehicle powertrain having a transmission and multiple prime movers including a primary prime mover coupled inline to the transmission and a secondary prime mover selectively coupled to the transmission by a substantially concentric coupling, the method comprising the steps of: determining powertrain torque demand; determining torque available from the primary prime mover and the transmission within its present gear ratio; comparing the powertrain torque demand with the torque available from the primary prime mover and the transmission within its present gear ratio; increasing output of the primary prime mover, if the powertrain torque demand does not exceed the torque available from the primary prime mover and the transmission within its present gear ratio; downshifting the transmission to a lower gear ratio, if torque demand exceeds torque available from the primary prime mover and the transmission within its present gear ratio; comparing torque demand to torque available from the primary prime mover and the transmission within its downshifted gear ratio; increasing output of the primary prime mover, if torque demand does not exceed torque available from the primary prime mover and the transmission within its downshifted gear ratio; activating the secondary prime mover and increasing output of the secondary prime mover to meet the torque demand, if torque demand exceeds torque available from the primary prime mover and the transmission within its downshifted gear ratio; and upshifting the transmission to a higher gear ratio.