| 摘要 |
<p>PURPOSE: To prevent the misjudgment of increasing emission and catalyst deterioration resulting from catalyst poisoned by sulfur by providing a sulfur poisoning detection means which detects catalyst deterioration by sulfur poisoning, and changing the control parameter of an engine if deterioration by sulfur poisoning is detected. CONSTITUTION: During the operation of an engine, poisoning is judged, utilizing a characteristic that the larger the content of sulfur is, the smaller the maximum output of O2 sensor 16 on the downstream side becomes. If sulfur poisoning of a ternary catalyst 14 is detected, air-fuel ratio feedback control is stopped, and the value of air-fuel ratio correction coefficient is changed to a prescribed value so that the air-fuel ratio of mixture supplied to the engine 1 may be on the richer side than a theoretical air-fuel ratio, and the rich condition of air-fuel ratio is maintained over a prescribed time. The sulfur in the ternary catalyst 14 is discharged as oxygen sulfide. After a prescribed time has passed, air-fuel ratio control is returned to ordinary feedback control to detect the deterioration of the ternary catalyst 14.</p> |
