Internal combustion engine misfire detecting device and misfire detecting method

An internal combustion engine misfire detecting device for detecting a misfire of an internal combustion engine having a plurality of cylinders, the internal combustion engine misfire detecting device comprising:

• a pulsating component acquisition unit for frequency-analyzing operation parameter data indicating a change over time in an operation parameter correlated with an overall operation status of the plurality of cylinders and acquiring a pulsating component spectrum that is a spectrum at a frequency of pulsation of the internal combustion engine;
• a change rate parameter acquisition unit for acquiring a change rate parameter indicating a degree of a change in an operating parameter correlated with the overall operation status of the plurality of cylinders;
• and
• an all-cylinder misfire determination unit for determining that an all-cylinder misfire has occurred in the internal combustion engine in a case where the pulsating component spectrum acquired by the pulsating component acquisition unit falls below a first threshold value and an absolute value of the change rate parameter acquired by the change rate parameter acquisition unit exceeds a fourth threshold value,
• wherein the all-cylinder misfire determination unit determines the all-cylinder misfire without detecting a misfire for each of the plurality of cylinders to avoid an amount of non-combustion gas from increasing due to occurrence of the all-cylinder misfire.

An internal combustion engine misfire detecting method for detecting a misfire of an internal combustion engine having a plurality of cylinders, the internal combustion engine misfire detecting method comprising:

• a pulsating component acquisition step for frequency-analyzing operation parameter data indicating a change over time in an operation parameter correlated with an overall operation status of the plurality of cylinders and acquiring a pulsating component spectrum that is a spectrum at a frequency of pulsation of the internal combustion engine;
• a difference parameter acquisition step for acquiring a difference parameter correlated with a degree of a difference in an operation of each of the plurality of cylinders;
• and
• an all-cylinder misfire determination step for determining that an all-cylinder misfire has occurred in the internal combustion engine in a case where the pulsating component spectrum acquired through the pulsating component acquisition step falls below a first threshold value and the difference parameter acquired through the difference parameter acquisition step falls below a second threshold value,
• wherein the all-cylinder misfire determination unit determines the all-cylinder misfire without detecting a misfire for each of the plurality of cylinders to avoid an amount of non-combustion gas from increasing due to occurrence of the all-cylinder misfire.

An internal combustion engine misfire detecting method for detecting a misfire of an internal combustion engine having a plurality of cylinders, the internal combustion engine misfire detecting method comprising:

• a pulsating component acquisition step for frequency-analyzing operation parameter data indicating a change over time in an operation parameter correlated with an overall operation status of the plurality of cylinders and acquiring a pulsating component spectrum that is a spectrum at a frequency of pulsation of the internal combustion engine;
• a change rate parameter acquisition step for acquiring a change rate parameter indicating a degree of a change in an operating parameter correlated with the overall operation status of the plurality of cylinders;
• and
• an all-cylinder misfire determination step for determining that an all-cylinder misfire has occurred in the internal combustion engine in a case where the pulsating component spectrum acquired through the pulsating component acquisition step falls below a first threshold value and an absolute value of the change rate parameter acquired through the change rate parameter acquisition step exceeds a fourth threshold value,
• wherein the all-cylinder misfire determination unit determines the all-cylinder misfire without detecting a misfire for each of the plurality of cylinders to avoid an amount of non-combustion gas from increasing due to occurrence of the all-cylinder misfire.