DEVICE FOR DETECTING CATALYST DEGRADATION OF INTERNAL COMBUSTION ENGINE, EXECUTING DEGRADATION DETECTION OF CATALYST BY DEGRADATION DETECTION UNIT

摘要

PURPOSE: A device for detecting catalyst degradation of an internal combustion engine is provided to exactly determine degradation of a catalyst although the standard of catalyst degradation is set rigidly. CONSTITUTION: A device for detecting catalyst degradation of an internal combustion engine(1) comprises catalysts(3,4) installed to an exhaust passage(2) of the internal combustion engine; a catalyst temperature-detecting unit(13) detecting the temperature of the catalysts; and a degradation-detecting unit(10) executing degradation detection of the catalysts when the temperature of the catalysts detected from the catalyst temperature-detecting unit is over the activating temperature of the catalysts and is in a specific temperature zone where Nox purification efficiency of the catalysts is lowered. The catalyst includes CeO2 as an oxygen occlusion agent.