| 摘要 |
<p>PURPOSE:To detect deterioration of a catalyst with good accuracy regardless of operating condition of an engine by providing a catalyst deterioration detecting means for detecting deterioration of a catalytic converter rhodium while using a locus length ratio, an area ratio and the degree of transient change of operating condition of an internal combustion engine. CONSTITUTION:A means E is provided for feedback-controlling the air fuel ratio of an engine A to a theoretical air fuel ratio on the basis of the output of an upstream side air fuel ratio sensor C provided in the exhaust passage of the upstream side of a catalytic converter rhodium B. A locus length ratio calculating means is provided for calculating the ratio between the output locus length of the upstream side air fuel ratio sensor C and the output locus length of a downstream side air fuel ratio sensor D during feedback control. Furthermore, an area ratio caluting means for calculating the ratio between an area enclosed by the output of the sensor C and a reference value, and an area enclosed by the output of the sensor D and the reference value is provided and a transient degree dectecting means for detecting the degree of transient change of operating condition of an internal combustion engine is also provided. Deterioration of a catalyst is judged by a means for detecting deterioration of the catalytic converter rhodium, while using the locus length ratio, a area ratio, and the degree of transient change.</p> |
