| 摘要 |
PURPOSE:To aim at reducing the blow-out of fresh air from an engine cylinder and as well at enhancing the combustion of fuel gas, by allowing scavenging air fed under pressure from a crank chamber to impinge upon a wall which forms a scavenging passage or a vent hole. CONSTITUTION:When scanvenging air flows into a scavenging passage 12 from a crank chamber 6 through the inlet port 15 of the scanvenging passage 12 during scavenging cycle, the scavenging air impinges upon the outer wall 24 of the scavenging passage formed in a crank casing 2, then reaches a scavenging hole 10 where the scavenging air impinges upon the upper wall 9 of the scavenging hole 10 and thereafter flows into the engine cylinder. The fact that scavenging air impinges upon various places in the scavenging system before it flows into the engine cylinder, results in lowering the flow rate of scavenging air, which is particularly remarkable concerning an initial scanvenging process during which the flow rate of scavenging air is high, and the high flow rate component of scavenging air in the scavenging passage. |
