| 摘要 |
PURPOSE:To induct new charged air to be sufficiently sucked also to the side of a main combustion chamber from a high load use intake passage when the valve timing is overlapped, by opening the high load use intake passage to both the main combustion chamber and a squish zone. CONSTITUTION:An engine main unit 1 forms a combustion chamber 6 between a cylinder head 3 and the upper surface of a piston 5 further a main combustion chamber 8 in a head internal wall surface 3a by a recessed part 7. The recessed part 7 opens the first intake port 11 and the first exhaust port 13, and the other port is opened to a flat part being a squish zone excepting the recessed part 7. When the valve timing is overlapped in the end of an exhaust stroke in high loaded operation with a shutter valve 22 being opened, a large amount of new charged air is allowed to flow into the main combustion chamber 8 from a high load use intake passage 21 mainly through the first intake port 11. In this way, residual combustion gas in the main combustion chamber 8 is sufficiently scavenged in a short period. |
