| 摘要 |
PURPOSE:To reduce the pulsation of exhaust gas to aim at enhancing the effect of sound-silencing and at lowering the back pressure, by forming a plurality of expansion chambers in an auxiliary exhaust passage through which exhaust gas in a muffler is led into water in a water jacket, so that the exhaust gas in the muffler is expanded in a multi-stage manner through these expansion chambers. CONSTITUTION:Engine exhaust gas is introduced into a muffler 40 from an exhaust port formed in an exhaust guide, through an exhaust manifold 50. Two expansion chambers 88A, 88B are formed adjacent to a vertically elongated auxiliary exhaust passage 86 which is formed in the front section of the muffler 40 and which is closed at the lower surface of the exhaust gide. The inside of the muffler 40 is communicated with the expansion chambers 88A, 88B and the auxiliary exhaust passage 86 through openings formed in the partition walls of the muffler 40. The lower end of the auxiliary exhaust passage 86 is positioned at a predetermined depth in the water jacket containing therein water of a fixed level. |
