Misfire detection device for internal combustion engine, misfire detection method for internal combustion engine, and memory medium

A misfire detection method for an internal combustion engine, the misfire detection method being employed in the internal combustion engine including cylinders, the misfire detection method comprising:

• deactivating, by misfire detection circuitry, combustion control for air-fuel mixture in a deactivated cylinder serving as a specified one of the cylinders;
• obtaining, by the misfire detection circuitry, a value of a combustion variable, the combustion variable indicating a combustion state in each of the cylinders, a sensor detecting a physical quantity corresponding to the combustion state of the air-fuel mixture in each of the cylinders, the combustion variable being defined by a detection value of the sensor;
• determining, by the misfire detection circuitry, whether a misfire has occurred in a determined cylinder serving as a cylinder subject to a determination of whether the misfire has occurred on condition that a divergence degree is greater than or equal to a specific amount during the execution of the deactivating combustion control,
• an occurrence point in time of each of compression top dead centers of cylinders adjacent to the deactivated cylinder being adjacent to an occurrence point in time of a compression top dead center of the deactivated cylinder,
• the cylinders adjacent to the deactivated cylinder including the determined cylinder and a cylinder different from the determined cylinder and adjacent to the deactivated cylinder,
• the divergence degree being between the value of the combustion variable of the cylinder different from the determined cylinder and adjacent to the deactivated cylinder and the value of the combustion variable of the determined cylinder;
• and
• controlling, by the misfire detection circuitry, predetermined hardware based on a determination result of whether the misfire has occurred in the determined cylinder,
• wherein the cylinders adjacent to the deactivated cylinder and the cylinder different from the determined cylinder and adjacent to the deactivated cylinder are cylinders in which the combustion control has been executed.

A non-transitory computer-readable memory medium that stores a program for causing a processor to execute a misfire detection process for an internal combustion engine, the misfire detection process being employed in the internal combustion engine including cylinders, wherein

• the misfire detection process includes:
• deactivating, by misfire detection circuitry, combustion control for air-fuel mixture in a deactivated cylinder serving as a specified one of the cylinders;
• obtaining, by the misfire detection circuitry, a value of a combustion variable, the combustion variable indicating a combustion state in each of the cylinders, a sensor detecting a physical quantity corresponding to the combustion state of the air-fuel mixture in each of the cylinders, the combustion variable being defined by a detection value of the sensor;
• determining, by the misfire detection circuitry, whether a misfire has occurred in a determined cylinder serving as a cylinder subject to a determination of whether the misfire has occurred on condition that a divergence degree is greater than or equal to a specific amount during the execution of the deactivating combustion control,
• an occurrence point in time of each of compression top dead centers of cylinders adjacent to the deactivated cylinder being adjacent to an occurrence point in time of a compression top dead center of the deactivated cylinder,
• the cylinders adjacent to the deactivated cylinder including the determined cylinder and a cylinder different from the determined cylinder and adjacent to the deactivated cylinder,
• the divergence degree being between the value of the combustion variable of the cylinder different from the determined cylinder and adjacent to the deactivated cylinder and the value of the combustion variable of the determined cylinder;
• and
• controlling, by the misfire detection circuitry, predetermined hardware based on a determination result of whether the misfire has occurred in the determined cylinder,
• wherein the cylinders adjacent to the deactivated cylinder and the cylinder different from the determined cylinder and adjacent to the deactivated cylinder are cylinders in which the combustion control has been executed.