Patent ID: 8302378
Filing Date: 2012-11-06
Classification: F01N,F02D,Y02T

Abstract:
1. A degradation diagnosis device for determining degradation of a catalyst comprising: an outflow exhaust temperature sensor disposed downstream of the catalyst for detecting an outflow exhaust temperature of an exhaust gas flowing out of the catalyst; and an electronic control unit configured, with executable programmed logic, to perform: changing an exhaust air-fuel ratio of an internal combustion engine to a rich side; estimating an inflow exhaust temperature which is a temperature of an exhaust gas flowing into a catalyst; and determining degradation of the catalyst by finding a temperature increasing degree of the outflow exhaust temperature at the time the exhaust air-fuel ratio is changed to the rich side, in respect to each of a plurality of the inflow exhaust temperatures, and finding a grade of the temperature increasing degree based upon the inflow exhaust temperature and the temperature increasing degree to determine degradation of the catalyst based upon at least one of a maximum value of the grade and the inflow exhaust temperature corresponding to the maximum value.