Patent ID: 7568337

Claim:
A device that detects a state of thermal degradation of an exhaust purifying catalyst, compromising: a degree of thermal degradation calculating unit that is programmed to calculate a degree of thermal degradation of the exhaust purifying catalyst by integrating a rate of progress of thermal degradation of the exhaust purifying catalyst at every predetermined time period; and a determining unit that is programmed to determine a state of thermal degradation of the exhaust purifying catalyst based on the degree of thermal degradation calculated by the thermal degradation calculating unit; wherein the calculating unit is programmed to calculate the rate of progress of thermal degradation of the exhaust purifying catalyst at a present time period based on an integrated value of the rate of progress of thermal degradation at an immediately preceding time period and temperature of the exhaust purifying catalyst at the present time period, and programmed to calculate an accumulated value for the degree of thermal degradation of the exhaust purifying catalyst by cumulatively adding said degree of thermal degradation calculated up to the immediately preceding time period.