| 摘要 |
PURPOSE:To enable complete combustion of lean mixture in a four-cycle internal combustion engine, by providing a scavenging valve in a cylinder head, said scavenging valve being opened and closed at a position near the top dead center between the exhaust stroke and the suction stroke, and thereby the scavenging residual gas in a combustion chamber effectually. CONSTITUTION:A carburetor 1 is formed with an air passage 5 into which air restricted by an air jet 5' is introduced, and the suction side of a pump 6 driven by a motor or an engine in association therewith is connected to the air passage 5. Further, in a cylinder head, there is provided a scavenging valve 7 which is opened and closed at a position near the top dead point between the exhaust stroke and the suction stroke of the engine. A port 8 of the scavenging valve 7 is directed, for instance, from the side of an exhaust valve to the side of a suction valve. The discharge side of the pump 6 is connected to an inlet port of the scavenging valve 7. With such an arrangement, it is enabled to scavenge the residual gas in a combustion chamber 9 of the engine effectually and to achieve complete combustion of air-fuel mixture even if the mixture is lean. |
