Patent ID: 7597648

Claim:
A vehicle powertrain for an electric hybrid vehicle providing improved energy efficiency and output torque during engine-off battery-only operation, said powertrain comprising: an electronically variable transmission (EVT) comprising: an input member operatively connected to receive mechanical rotary power from a vehicle engine; an output member to provide mechanical rotary power to motively propel said vehicle; a gear train configured to selectively and operatively couple said input member to said output member; a first motor/generator adapted to convert bi-directionally between electrical and mechanical power, said first motor/generator driveably coupled to said gear train, said motor/generator for receiving power from or providing power to said gear train; a second motor/generator adapted to convert bi-directionally between electrical and mechanical power, said second motor/generator driveably coupled to said gear train, said second motor/generator for receiving power from or providing power to said gear train; and at least one EVT torque transfer device selectively operable together with an input torque transfer device to configure said gear train into at least one electric power only fixed gear ratio electric drive mode; said input torque transfer device selectively engageable to torsionally resist rotation of said input member, said input torque transfer device operable together with said EVT torque transfer devices to configure said transmission to operate in one or more battery fixed gear modes, enabling both motor/generators to be used with additive power for electric propulsion or regenerative braking, said input torque transfer device improving electrical power to mechanical power conversion efficiency by reducing power circulation when said EVT is operated in electric drive, engine off mode; said input torque transfer device including one of or both of a one way clutch to ground and an input brake to ground, said one way clutch connected to said input member permitting said input member to rotate in a positive direction as normally driven by said engine while preventing said input member from rotating in a negative direction, said input brake to ground selectively operable to resist rotation of said input member by frictionally braking said input member to ground; an energy storage device electrically interfaced to said motor/generators for providing electrical power to and receiving electrical power from said motor/generators; and a control unit adapted to selectively control motoring/generating modes including power and torque of each motor/generator, said control unit selectively operating said EVT torque transfer devices, said control unit adapted to selectively engage said input brake device, wherein said engine is in an off condition before said input brake is engaged and wherein said input brake is released before said engine is started.