Controller and control method for internal combustion engine

A control method for an internal combustion engine, wherein

• the internal combustion engine includes
• a three-way catalyst that is arranged in an exhaust passage and purifies exhaust gas,
• a particulate filter that is arranged in a section of the exhaust passage at a downstream side of the three-way catalyst to trap particulate matter contained in the exhaust gas,
• an exhaust gas recirculation passage that extends from a section of the exhaust passage at an upstream side of the particulate filter and communicates with an intake passage to recirculate the exhaust gas to the intake passage, and
• an exhaust gas recirculation valve that opens and closes a flow path of the exhaust gas recirculation passage,
• the internal combustion engine is configured to burn, in a cylinder, air-fuel mixture containing fuel injected from an fuel injection valve by spark discharge of an ignition device,
• the control method comprises:
• performing a fuel introduction process, in which, when stopping combustion in the cylinder under a situation in which a crankshaft of the internal combustion engine is rotating, the fuel introduction process causes fuel to be injected from the fuel injection valve and causes the fuel to flow out unburned from inside the cylinder to the exhaust passage,
• controlling opening and closing of the exhaust gas recirculation valve, wherein an opening degree of the exhaust gas recirculation valve at a point in time when a state in which an execution condition of the fuel introduction process is not satisfied is switched to a state in which the execution condition of the fuel introduction process is satisfied is a preliminary opening degree, and
• causing an opening degree of the exhaust gas recirculation valve to be smaller than the preliminary opening degree during execution of the fuel introduction process.

A non-transitory computer readable memory medium storing a program that causes a processor to execute a controlling process of an internal combustion engine, wherein

• the internal combustion engine includes
• a three-way catalyst that is arranged in an exhaust passage and purifies exhaust gas,
• a particulate filter that is arranged in a section of the exhaust passage at a downstream side of the three-way catalyst to trap particulate matter contained in the exhaust gas,
• an exhaust gas recirculation passage that extends from a section of the exhaust passage at an upstream side of the particulate filter and communicates with an intake passage to recirculate the exhaust gas to the intake passage, and
• an exhaust gas recirculation valve that opens and closes a flow path of the exhaust gas recirculation passage,
• the internal combustion engine is configured to burn, in a cylinder, air-fuel mixture containing fuel injected from an fuel injection valve by spark discharge of an ignition device, and
• the controlling process includes
• performing a fuel introduction process, in which, when stopping combustion in the cylinder under a situation in which a crankshaft of the internal combustion engine is rotating, the fuel introduction process causes fuel to be injected from the fuel injection valve and causes the fuel to flow out unburned from inside the cylinder to the exhaust passage,
• controlling opening and closing of the exhaust gas recirculation valve, wherein an opening degree of the exhaust gas recirculation valve at a point in time when a state in which an execution condition of the fuel introduction process is not satisfied is switched to a state in which the execution condition of the fuel introduction process is satisfied is a preliminary opening degree, and
• causing an opening degree of the exhaust gas recirculation valve to be smaller than the preliminary opening degree during execution of the fuel introduction process.