CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE FOR VEHICLE

摘要

PROBLEM TO BE SOLVED: To transfer to the lean mode operation when a drive assisting by a motor is started even during stoichicemetric mode operation. SOLUTION: In a hybrid vehicle in which the drive is assisted by a motor, possibility of lean mode operation is determined from a reduction of the engine load by the drive assist in response to the start of the drive assist during operation with the theoretical air-fuel ratio, and the air-fuel ratio of the engine is controlled to be lean in accordance with the determination. The temperature of a lean NOx catalyst is sensed, and operation with the lean air-fuel ratio is allowed only when it lies within a activation region in which the catalyst exerts the NOx purifying performance. Thereby the enhancement of fuel consumption as well as enhancement of the purifying effect for exhaust gas are achieved.