Control system for engine

A control device for an engine provided in a vehicle including an accelerator pedal, the control device comprising:

• memory and a processor that control an injector of the engine and an intake air amount adjustment device that adjusts an intake air amount that is an amount of air drawn into a combustion chamber of the engine, the control device being configured to:
• estimate a catalyst temperature that is a temperature of a catalyst device of the engine;
• implement a fuel cut that stops fuel injection by the injector when an accelerator opening degree detected by an accelerator sensor is equal to or less than a predetermined accelerator determination opening degree;
• when the fuel cut is implemented while the catalyst temperature is equal to or higher than a predetermined determination temperature, implement an intake air amount increase control that controls the intake air amount adjustment device so that the intake air amount is larger than while the catalyst temperature is lower than the determination temperature;
• and
• control the intake air amount adjustment device so that an increase rate of the intake air amount is decreased as the catalyst temperature increases.

A control method for an engine provided in a vehicle including an accelerator pedal, an engine body including a combustion chamber, an exhaust passage and an intake passage each connected to the engine body, an injector that supplies fuel to the combustion chamber, an intake air amount adjustment device that adjusts an intake air amount that is an amount of air drawn into the combustion chamber, a catalyst device provided in the exhaust passage to purify exhaust gas, an accelerator sensor that detects an accelerator opening degree, the accelerator opening degree being an opening degree of the accelerator pedal, and a control device that controls the injector and the intake air amount adjustment device, the control method comprising:

• estimating a catalyst temperature that is a temperature of the catalyst device;
• implementing a fuel cut that stops fuel injection by the injector when the accelerator opening degree detected by the accelerator sensor is equal to or less than a predetermined accelerator determination opening degree;
• when the fuel cut is implemented while the catalyst temperature is equal to or higher than a predetermined determination temperature, implementing an intake air amount increase control that controls the intake air amount adjustment device so that the intake air amount is larger than while the catalyst temperature is lower than the determination temperature;
• and
• controlling the intake air amount adjustment device so that an increase rate of the intake air amount is decreased as the catalyst temperature increases.