| 摘要 |
A means of detecting anomalies (S116, S118) determines when there is an anomaly in the oxygen collector when the theoretical oxygen storage capacity of the catalyst, calculated from measurements of the oxygen content of the exhaust gases upstream of the catalyst, has passed the maximum storage capacity of the catalyst The oxygen collector (28) is placed downstream of a catalyst (24) for purifying exhaust gases from an internal combustion engine (10). A collector (26) upstream of the catalyst gives an output corresponding to an air-fuel ratio in the exhaust. Means of calculating the storage time capacity (50) gives a theoretical oxygen storage capacity of the catalyst by determining the amount of oxygen in the exhaust gases entering the catalyst over a period during which the oxygen collector provides a rich source and the upstream collector produces a poor source. The upstream collector is an air-fuel ratio detector and includes means of calculating the air-fuel ratio to obtain a difference DELTAA/F between the air-fuel ratio detected by the upstream collector and a stoeometric air-fuel ratio. There are also means of detecting how much fuel is supplied and the calculating unit works out the quantity of oxygen in the exhaust gases from the different DELTAA/F and the amount of fuel supplied. When the air-fuel ratio supplied to the engine is rich, the oxygen collector provides a poor output and vice versa. When the oxygen collector produces a poor output, the fuel-air ratio to the engine is forced to a target ratio.
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