Misfire detection device for internal combustion engine

A misfire detection device for an internal combustion engine including a plurality of cylinders and a crankshaft configured to be connected to a rotating shaft of a transmission device, the misfire detection device comprising:

• a rotation angle sensor configured to output a detected angle signal of the rotating shaft by detecting a rotation angle of the rotating shaft of the transmission device;
• a crank angle sensor configured to output a crank signal by detecting a crank angle of the crankshaft of the internal combustion engine;
• and
• an electronic control unit configured to
• calculate first time series data based on the detected angle signal of the rotating shaft and the crank signal of the crankshaft in a connected state that is a state where the rotating shaft and the crankshaft are connected to each other, the first time series data being time series data of a predetermined frequency component in time series data acquired by removing a component caused by torsion between the crankshaft and the rotating shaft from a rotational behavior of the crankshaft shown on the crank signal,
• generate, in the connected state, second time series data that is acquired by removing the predetermined frequency component from time series data indicating the rotational behavior of the crankshaft,
• generate third time series data that indicates the rotational behavior of the crankshaft and is acquired by combining the second time series data with the predetermined frequency component based on the first time series data and the second time series data, and
• determine presence of misfire in the internal combustion engine based on the third time series data.