| 摘要 |
PURPOSE:To reduce the blow-by of a fresh air outside a cylinder by controlling the inflow route for scavenging through the cylinder with two or more of scavenging passages different in the sectional area to each other. CONSTITUTION:The pressures in a crank chamber 8, a main scavenging passage 16 and a sub scavenging passage 17 are almost the same immediately before the scavenging and with the lowering of a piston 4, they come down as the scavenging is subdued by opening a scavenging port 15. Gas flowing through the main scavenging passage 16 by the inlet 18 thereof lowers in the flow rate due to the resistance and length of the passage to bring down the pressure on the side of the scavenging port 15 within the main scavenging passage. Since a scavenging air is fed passing through the sub scavenging passage 17 short-circuited to this position from the crank chamber, the pressure in the scavenging passage falls gradually. Therefore, the scavenging air is made smooth as a whole as flowing into a cylinder bore 3. |
