| 摘要 |
PURPOSE:To prevent seawater from coming into each cylinder from an exhaust port by collecting the exhaust ports of the plurality of the cylinders of an engine so as to be disposed in a place above the exhaust port at the uppermost position, and concurrently forming each reverse flow preventive section therein. CONSTITUTION:An outboard motor 1 to be mounted onto a hull 2 is equipped with an engine 10 having a plurality of cylinders 15 at the upper section of the motor. The exhaust ports 26 of the plurality of the cylinders 15 of the engine 10 are arranged in the vertical direction. These exhaust ports 26 are collected to a collecting exhaust passage 26 at one side so as to be extended upward. The exhaust ports 26 of the plurality of the cylinders are so collected as to be positioned in a place above the exhaust port 26 at the uppermost position, moreover, an exhaust passage A is formed, which leads exhaust gas to an underwater exhaust port 48 located under the sea level. And each reverse flow preventive section A1 is formed in an upper section located above the exhaust port 26 at the uppermost position of the exhaust passage while being protruded above the area in front and in the rear on the border of the aforesaid upper section. By this constitution, it is possible to prevent seawater from coming in from the exhaust port of the engine. |
