| 摘要 |
PURPOSE:To prevent a catalyst from being abnormally heated, by stopping control for lean mixture combustion and resuming feedback control, when the control for lean mixture combustion has lasted for more than a prescribed time or the temperature of the catalyst of an exhaust gas purifier has exceeded a prescribed level. CONSTITUTION:When a feedback control condition is present, the presence of a partial lean condition and the comparison of the temperature (t) of a catalyst detected by a sensor 28, with a prescribed temperature T, are discriminated. If the partial lean condition is not present or if the condition is present and the catalyst temperature (t) is higher than the prescribed level (T), during the execution of partial lean control after the discrimination, the partial lean control is immediately replaced by feedback control. As a result, the catalyst is prevented from being abnormally heated, if an upper temperature limit is previously set depending on the kind of the catalyst. The shift of the feedback control back to the partial lean control is prohibited until the temperature of the catalyst becomes lower than the prescribed level T. |
