| 摘要 |
PURPOSE:To permit a torque fluctuation caused when air-fuel ratio is switched to be absorbed, by providing a control means for opening and closing an intake air supply means when a setting of the air-fuel ratio is switched between rich and lean. CONSTITUTION:A control circuit 46 controls a fuel supply amount from a fuel injector 32 of which air-fuel ratio setting is switched between lean and rich depending upon a load on an engine. Further, there is disposed a bypass control valve 42 capable of controlling an intake air amount independent of a usual intake air throttle valve 38 in a bypass passage 40. The control circuit 46 controls opening and closing of the bypass control valve 42 according to an intake air pipe pressure sensed by an intake air pipe pressure sensor 54 when the air-fuel ratio setting is switched between lean and rich. That is, when a load is increased to a prescribed intake air pipe pressure, the air-fuel ratio becomes rich and the bypass control valve 42 is closed simultaneously and an amount of intake air is reduced by the amount. With this arrangement, a smooth switching can be carried out without causing an abrupt torque change.
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