| 摘要 |
PURPOSE:To prevent drop of the volumetric efficiency due to presence of a discharge passage, by forming the discharge passage with a material having a heat conductivity lower than that of the material of a cylinder, and thereby preventing temperature rise of the cylinder near the discharge passage. CONSTITUTION:On the inside of a discharge passage 23, there is provided a heat- insulating cylindrical sleeve 24 which is made of a material having a heat conductivity sufficiently lower than that of the material of a cylinder. Therefore, the temperature rise of the cylinder near the discharge passage 23 that is caused by the high-temperature exhaust gas passed through the discharge passage 23 is extremely small since the heat-insulating cylindrical sleeve 24 functions to reduce the amount of heat transmitted to the cylinder from the high-temperature exhaust gas passed through the discharge passage 23. Thus, since the amount of heat transmitted from the surface of the cylinder wall is reduced, it is enabled to prevent drop of the volumetric efficiency. |
