PURPOSE: To generate a swirl during low load conditions of an engine to improve combustion performance thereof by concentrating fuel-air mixture into an intake passage adjacent to a secondary intake port and supplying the same toward a primary intake port.
CONSTITUTION: During low load conditions of an engine 1, the operation of a secondary intake valve 9 is stopped and an intake passage 6a adjacent to a primary intake port 4 is closed by a shut-off valve 13. The fuel-air mixture in an intake passage 6 is concentrated into an intake passage 6a adjacent to a secondary intake port 5, and then supplied through the intake passage 6a toward the primary intake port 4. As the fuel-air mixture is discharged along a tangent of the peripheral wall of a combustion chamber 2, a strong swirl is generated.
KANEKO TADASHI
UEDA KAZUHIKO
