Abstract: A temporal change of a turbo rotation speed of a turbocharger is detected for each cycle of an engine. A first vibration component corresponding to each of cylinders is specified from a pulsation component included in the temporal change of the turbo rotation speed, and the first vibration components for each of the cylinders are integrated over a plurality of cycles. A variation of combustion states in the plurality of cylinders is calculated by comparing integration results among the cylinders.

Abstract: The present invention provides a device and method for detecting a misfire in an engine, the device being provided with: a rotation speed sensor (43) as a supercharger rotation speed measurement unit for measuring a rotation speed (Nt) of a supercharger (23); a misfire index calculation unit (51) that calculates a misfire index (Yt) from a degree of change in the rotation speed (Nt) of the supercharger (23), the rotation speed being measured by the rotation speed sensor (43); and a misfire determination unit (52) that determines a misfire in an engine (10) when the misfire index (Yt) calculated by the misfire index calculation unit (51) exceeds a pre-set determination value (D).

Abstract: A temporal change of a turbo rotation speed of a turbocharger is detected for each cycle of an engine. A first vibration component corresponding to each of cylinders is specified from a pulsation component included in the temporal change of the turbo rotation speed, and the first vibration components for each of the cylinders are integrated over a plurality of cycles. A variation of combustion states in the plurality of cylinders is calculated by comparing integration results among the cylinders.

Abstract: The present invention provides a device and method for detecting a misfire in an engine, the device being provided with: a rotation speed sensor (43) as a supercharger rotation speed measurement unit for measuring a rotation speed (Nt) of a supercharger (23); a misfire index calculation unit (51) that calculates a misfire index (Yt) from a degree of change in the rotation speed (Nt) of the supercharger (23), the rotation speed being measured by the rotation speed sensor (43); and a misfire determination unit (52) that determines a misfire in an engine (10) when the misfire index (Yt) calculated by the misfire index calculation unit (51) exceeds a pre-set determination value (D).

Abstract: An engine abnormality detection device for detecting variation of a combustion state of each of a plurality of cylinders of an engine, the engine abnormality detection device includes: a rotation information acquisition part configured to obtain rotation information related to a rotation state of the engine; a frequency analysis part configured to perform frequency analysis of the rotation information, the frequency analysis part being configured to calculate a component of fNe and a component fcyl through the frequency analysis of the rotation information, where fNe is a frequency of a single cycle of the engine and fcyl is a frequency of pulsation of the engine; and a detection part configured to detect variation of exhaust energy of each cylinder on the basis of the component of fNe and the component of fcyl.