| 摘要 |
PURPOSE:To improve combustion stability at the time of controlling EGR by feeding an air-fuel mixture richer than a stoichiometric air-fuel ratio, to the surroundings of an ignition plug. CONSTITUTION:When an engine reaches a predetermined driving condition, a swirl control valve 6 is closed by a control unit 22 so as to limit the amount of air to a second intake port 4B. Assist air is fed by a fuel injection valve 8 from an auxiliary air channel 17 to only the second injection hole directed to the second intake port 4B. A first intake valve 5A is set so that its opening time and closing time become earlier than those of a second intake valve 5B, and the fuel injection timing of the fuel injection valve 8 is set so that the fuel injected from the second injection hole reaches the inside of the second intake port 4B when the second intake valve 5B is going to be closed. An air-fuel mixture layer of high air-fuel ratio, an air-fuel mixture layer of the air-fuel ratio closer to a stoichiometric air-fuel ratio, and an EGR gas layer are formed in this order from the center part to the outside of a cylinder 1.
|
