| 摘要 |
PURPOSE:To improve the catalytic action and the engine performance, by effecting the suction stroke of air-fuel mixture in lean-burn region and the suction stroke of mixture of the theoretical air-fuel ratio by a predetermined ratio at the time of steady operation of an engine when the rate of load change is lower than a prescribed value. CONSTITUTION:At the time of steady operation of an engine when the rate of load change is lower than a prescribed value, an electronic control circuit 20 determines the sequence and pattern of the combination of the theoretical air- fuel ratio and the air-fuel ratio of lean-burn region, and fuel supply is controlled by calculating the required fuel supply rate from the detected air-fuel ratio. By thus supplying air-fuel mixture of the theoretical air-fuel ratio and mixture of lean-burn region alternately to a cylinder at the time of steady operation of the engine, the engine performance is improved as compared with the casse in which the air-fuel ratio is set always in lean-burn region. At the same time, the exhaust-gas purifying efficiency of a catalyst can be raised in case of exhaust emission control using a catalyst. |
