Deterioration determining system for an exhaust gas purifier of an internal-combustion engine

摘要

The invention provides a deterioration determining apparatus capable of accurately determining the deterioration of an exhaust gas purifier in an internal-combustion engine. <??>The deterioration determining apparatus applies a high-pass filter or a band-pass filter to outputs of an exhaust gas sensor installed downstream of the purifier to extract frequency components associated with the deterioration degree of the purifier. Then, the deterioration determining apparatus calculates squares of the extracted outputs. The apparatus further applies a sequential type statistical algorithm to the squares to calculate a deterioration determining parameter for the purifier. The apparatus finally determines deterioration of the purifier using the deterioration determining parameter. <IMAGE>