| 摘要 |
PROBLEM TO BE SOLVED: To reduce the leak of sound from a silencer by providing a sound isolating plate opening or closing an air intake port on the air intake port of the silencer. SOLUTION: A sound isolating plate 62 is provided on the air intake port 33b of a silencer 33 rotatably around a rotary shaft 63. A lever 66 is fixed to the sound isolating plate 62, and the end section of the lever 66 is connected to a throttle cam 69 via a rod 67. When the valve element 32b of a throttle valve 32 is rotated in the opening direction, the sound isolating plate 62 is rotated in the opening direction. When the valve element 32b is rotated in the closing direction, the sound isolating plate 62 is rotated in the closing direction. When the aperture of the valve element 32b of the throttle valve 32 is small, i.e., when an air inflow quantity is small, the sound isolating plate 62 having a small aperture does not leak the sound in an engine 6 to the outside. Lubricating oil can be prevented from flowing outward from the air intake port 33b of the silencer 33 by the sound isolating plate 62 to the utmost.
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