| 主权项 |
1. A control system for a spark-ignition internal combustion engine, the spark-ignition internal combustion engine including
an intake valve, an exhaust valve, an intake port, an ignition plug arranged near a center of an upper wall surface of a combustion chamber, the ignition plug being configured to ignite air-fuel mixture, and a port fuel injection valve arranged in the intake port, a direction in which the port fuel injection valve injects fuel being set such that an injected fuel is directed toward the center of the combustion chamber through an opening of the intake valve when fuel is injected during an open period of the intake valve, the control system comprising: an electronic control unit configured to: i) control a flow speed of gas around the ignition plug during ignition by changing a tumble flow between a first tumble flow and a second tumble flow, the first tumble flow being a tumble flow that a flow direction of gas around the ignition plug during ignition is a direction directed from the intake valve toward the exhaust valve in a second half of a compression stroke, the second tumble flow being a tumble flow that the flow direction of gas reverses from the direction directed from the intake valve toward the exhaust valve to a direction directed from the exhaust valve toward the intake valve in the second half of the compression stroke as a result of a change into a tumble flow having two swirl flow components in process of compression of the gas in the compression stroke, the two swirl flow components having mutually opposite rotational directions when the combustion chamber is viewed from an upper side; and ii) generate the second tumble flow by overlapping at least part of a fuel injection period of the port fuel injection valve with the open period of the intake valve. |
