| 摘要 |
PURPOSE:To effectively protect a catalyst from being overheated, by increasing the amount of fuel, when the temperature of the catalyst is above a predetermined value and the engine runs under a high load or at a high rotational speed, by an amount necessary for lowering the temperature of the catalyst. CONSTITUTION:A control unit 18 receives various control input data upon running of an engine 1, and computes a fuel injection pulse width T. Then, the condition whether the engine 1 runs under a high load or not, and as well the condition whether the engine runs at a high rotational speed or not are sucessively judged. When either one of both conditions is satistifed, a shut-off valve 17 is closed to cut off a secondary air fed to a catalyst 2 from a secondary air supply passage 4. Further, the condition whether the tenperature of the catalyst 2 exceeds a set temperature or not is judged, and if this condition is satisfied, the index (n) of the increment of fuel is renewed to (n+1) so that the above-mentioned injection pulse width T is renewed to T+DELTATXn to increase the injection pulse width T by DELTATXn. Further, a fuel injection valve 13 is controlled with this renewed injection pulse width. |
