| 摘要 |
PURPOSE:To kill a radiant noise in a specific frequency range without fail, by installing an enclosed-form resonance chamber, having an intake port of the engine radiant noise, in a part at the more suction upperstream side than a suction intake port of a carburetor in an internal empty space of a cowling covering the engine and the carburetor. CONSTITUTION:A suction manifold 15, a carburetor 16 and a suction box 17 are all connected to an engine 14 of an outboard motor 10, and these constituent parts are covered with a cowling 18. In this case, a resonant type muffler 24 is installed at both sides of the suction box 17 in an internal empty space of the cowling 18. And, the muffer 24 is constituted of an intake pipe 25 to be interconnected to the inside of the suction box 17 and an enclosed-form resonance chamber 27 to be interconnected to the intake pipe 25 via an intake port 26. With this constitution, in time of driving the outboard motor 10, a radiant noisd out of the engine 14 radiated out of a suction intake port 21 of the carburetor 16 is muffled at a extensive frequency range in cooperation with an expansion- contraction type muffling effect in the suction box 17 and afterward it is killed in a specific frequency range in cooperation with a resonant type muffling effect at the resonance chamber 27. |
