| abstract |
A hybrid vehicle employing a parallel hybrid system, using both an internal combustion engine and an electric motor for propulsion, comprises a propulsion mechanism having at least a first electric motor, an internal combustion engine, a clutch, a second electric motor, a transmission, and drive wheels, and constructed so that a crankshaft of the engine and a motor shaft of the first electric motor are connected to an input shaft of the clutch, and that a motor shaft of the second electric motor and an input shaft of the transmission are connected to an output shaft of the clutch to transmit a driving torque from the output shaft of the transmission to the drive wheels. An engine temperature sensor is provided for detecting an engine temperature. An electronic control unit is connected to the propulsion mechanism and the engine temperature sensor, for disengaging the clutch and stopping the engine during a standstill state of the hybrid vehicle, and for propelling the hybrid vehicle by a driving torque generated by the second electric motor when the hybrid vehicle starts, and for starting up the engine by the first electric motor and engaging the clutch after engine startup, during the warm-up of the engine. A variable valve timing control system is electrically connected to the control unit for adjusting an intake-valve closure timing to a predetermined retarded closure timing when the clutch is disengaged and for adjusting the intake-valve closure timing to a predetermined advanced closure timing after the clutch is engaged, after the engine warm-up. |