| 摘要 |
<p>PURPOSE:To accurately judge the degradation of catalytic converter rhodium when an instrumentation time is less than a predetermined time by measuring a time from when an internal combustion engine is shifted to rich operation condition to when the output of an air/fuel ratio sensor at the down stream side of the catalytic converter is reversed to rich condition. CONSTITUTION:Respective air/fuel ratio sensors c, d are provided at the upper and down stream sides of catalytic converter rhodium b provided at the exhaust passage a of an internal combustion engine and the air/fuel ratio of the internal combustion engine is adjusted by a means e according to those respective detected results. At this time, reverse between the lean and rich condition of the output of the down stream side air/fuel ratio sensor d is judged by a means (f). The operation condition of the internal combustion engine is judged by a means g that theoretical air/fuel ratio operation condition is shifted to rich operation condition. Further, a time from the shift to when the output of the down stream side air/fuel ratio sensor d is reversed from lean condition to rich condition is measured by a means h. When the measured time is less than a predetermined time, the degradation of the catalytic inverter rhodium b is judged by a means t.</p> |
