| 摘要 |
<p>PURPOSE: To achieve deterioration diagnosis for a catalyst at high precision while considering the activating state of the catalyst and an exhaust sensor. CONSTITUTION: Exhaust sensors 2A, 2B arranged upstream and downstream from a catalyst 1, a means 3 for feedback-controlling the quantities of fuel to be supplied to an engine on the basis of the output of the upstream exhaust sensor 2A, and a means 4 for judging the deterioration of the catalyst by comparing the reversing times of the upstream and downstream exhaust sensor outputs with a judging reference value are provided. Moreover a catalyst deterioration diagnostic device is provided with a means 6 for setting a different judging reference value according to the exhaust gas temperature, and a control means 7 for prohibiting the judgement of the catalyst deterioration when the exhaust gas temperature is less than the specified value, and for performing the judgement by the comparison with the judging reference value according to the exhaust temperature when the exhaust temperature exceeds the specified value.</p> |
