| 摘要 |
PURPOSE:To prevent creeps or pitching of a boss section precisely by utilizing an internal space of a hollow piston pin fitted into a piston boss section as a passage of the fresh air and the mixed gas from a pre-pressure chamber to a combustion chamber. CONSTITUTION:A hollow piston pin 8 is fitted into the boss section 7 of a piston 5. A concave section 9 of the piston 5 connects an inlet section 8a of the fresh air and the gas to a crankcase. When the piston 5 reaches the bottom dead point, the compressed mixed gas in the crankcase 6 is fed into a combustion chamber 4 by way of a passage A passing through a main scavenging passage 11 and a passage B passing through the concave section 9, the internal space of the piston pin 8 and a supplementary scavenging passage 10. Therefore, the pin 8 is cooled efficiently because the fresh air and the mixed gas with a low temperature pass through the internal space of the piston pin 8. Thereby, creeps or pitching of the boss section can be prevented precisely. |
