Hybrid vehicle powertrain and control therefor

Abstract

A powertrain assembly for an automotive vehicle having an interanal combustion engine and transmission gearing for delivering engine torque to traction wheels of a vehicle. An electric induction motor is situated in the torque flow path between the engine and the transmission. The induction motor complements engine torque which permits the engine to be turned off when the vehicle is at rest, thereby improving fuel economy and rendering undesirable exhaust gas emissions from the internal combustion engine. The torque multiplication that would normally be available from a hydrokinetic torque converter in the transmission is essentially replaced with auxiliary launch torque supplied by the induction motor during vehicle startup. The vibration damping function of a hydrokinetic torque converter during engine idle is also performed by the induction motor. Therefore, a hydrokinetic torque converter in the transmission in not necessary. The induction motor, during those operating modes of the vehicle when induction motor torque is not required to deliver driving torque, functions as an alternator during periods of regenerative braking with the internal combustion engine inactive and with the vehicle in a coast mode.