A hybrid vehicle includes an internal combustion engine, an electric motor/generator and a battery. The drivetrain includes a planetary gear in which the engine is coupled to the sun gear, the motor/generator to the ring gear and the vehicle wheels to the carrier of the planetary. A controller switches the vehicle between electric, assist, charge and regenerative modes of operation and substantially decouples the engine speed from the vehicle speed, enabling the engine to operate at peak efficiency. Additional overdrives are included to enable the engine to operate at optimum speed in the various modes of operation.
Ashok Nedungadi; Mark Walls; D. Dardalis