| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of accurately determining the deterioration of a catalyst converter. <P>SOLUTION: On the basis of output information from an exhaust sensor provided downstream to the catalyst converter in regard to the modulation of an exhaust air/fuel ratio, an amplitude correlation value of the exhaust air-fuel ratio downstream to the catalyst converter is obtained. A catalyst downstream modulation state detecting means (S12 to S20) obtaining a period rate correlation value during a period that the exhaust air-fuel ratio downstream to the catalyst converter is in a lean air-fuel ratio side as compared with a reference value, or a period that the catalyst converter is in a rich air-fuel ratio side, and a deterioration determining means determining the detrioration of the catalyst converter on the basis of the amplitude correlation value and the period rate correlation value, are provided. The deterioration determining means determines the detrioration of the catalyst converter by assigning weights to the amplitude correlation value so as to made an influence degree of the amplitude correlation value become larger than that of the period rate correlation value. <P>COPYRIGHT: (C)2004,JPO</p> |
