Controller and control method for internal combustion engine

A method for controlling an internal combustion engine, wherein the internal combustion engine includes:

• a fuel injection valve;
• a cylinder into which air-fuel mixture containing fuel injected by the fuel injection valve is introduced;
• an ignition device that ignites the air-fuel mixture introduced into the cylinder with a spark;
• an exhaust passage through which gas discharged out of the cylinder flows;
• and
• a three-way catalyst device arranged in the exhaust passage,
• wherein the method comprises:
• executing a fuel introduction process of introducing the air-fuel mixture, which contains the fuel injected by the fuel injection valve, into the exhaust passage without burning the air-fuel mixture in the cylinder;
• determining, during the execution of the fuel introduction process by the fuel introduction processor, whether afterfire, in which the air-fuel mixture burns at an upstream side of the three-way catalyst device in the exhaust passage, has occurred;
• and
• stopping, during the execution of the fuel introduction process by the fuel introduction processor, the fuel introduction process when determining in the determination process that the afterfire has occurred.

A controller configured to control an internal combustion engine, wherein the internal combustion engine includes:

• a fuel injection valve;
• a cylinder into which air-fuel mixture containing fuel injected by the fuel injection valve is introduced;
• an ignition device that ignites the air-fuel mixture introduced into the cylinder with a spark;
• an exhaust passage through which gas discharged out of the cylinder flows;
• and
• a three-way catalyst device arranged in the exhaust passage, wherein
• the controller includes processing circuitry configured to execute:
• a fuel introduction process of introducing the air-fuel mixture, which contains the fuel injected by the fuel injection valve, into the exhaust passage without burning the air-fuel mixture in the cylinder;
• a determination process of determining, during execution of the fuel introduction process by the fuel introduction processor, whether afterfire, in which the air-fuel mixture burns at an upstream side of the three-way catalyst device in the exhaust passage, has occurred;
• and
• a stopping process of stopping, during the execution of the fuel introduction process by the fuel introduction processor, the fuel introduction process when determining in the determination process that the afterfire has occurred.