Control method of air fuel ratio for hybrid vehicle and control device of air fuel ratio for hybrid vehicle

A control device for a hybrid vehicle comprising:

• a first motor configured to supply a generated electric power to a battery;
• a second motor configured to drive a driving wheel by the electric power from the battery, or the electric power generated by the first motor;
• an internal combustion engine configured to drive the first motor;
• and
• a controller configured to switch between a stoichiometric combustion in which a target air fuel ratio of the internal combustion engine is set to a theoretical air fuel ratio, and a lean combustion in which the target air fuel ratio is set to be leaner than the theoretical air fuel ratio,
• wherein when the combustion mode is switched from the lean combustion to the stoichiometric combustion while a request torque of the internal combustion engine is less than a predetermined value, the controller is configured to
• stop a fuel supply to the internal combustion engine,
• decrease an intake air amount of the internal combustion engine during the stop,
• set the target air fuel ratio of the internal combustion engine to the theoretical air fuel ratio, or the air fuel ratio richer than the theoretical air fuel ratio, in a state in which the intake air amount of the internal combustion engine is decreased, and
• restart the internal combustion engine,
• wherein when the combustion mode of the internal combustion engine is switched from the lean combustion to the stoichiometric combustion while the request torque of the internal combustion engine is greater than the predetermined value, the controller is configured to switch the target air fuel ratio with the fuel supply continued.