| 摘要 |
PROBLEM TO BE SOLVED: To increase the degree of freedom of the design for forming an opening in a simple structure, as well as to reduce the air flow speed near the opening to reduce the generation of a suction sound. SOLUTION: A projection 5 is provided near the part separated the most in the peripheral direction from a valve shaft 12, in the inner wall of a throttle body 1 between an opening 17 and a throttle valve 11. As a result, even though the opening 17 is formed near the part most distant in the peripheral direction from the valve shaft 11, the air flow speed near the opening 17 is reduced securely, so as to prevent pressure flactuation from generating resonance in an auxiliary air passage 7. Consequently, the generation of intake sound can be reduced. Furthermore, by a relatively simple structure of providing a projection 5, the air flow speed near the opening 17 can be reduced to reduce the generation of the intake sound, resulting in enhancing the designing freedom degree to form the opening 17 as well as reducing the manufacturing cost.
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