| 摘要 |
PROBLEM TO BE SOLVED: To inhibit radiation sounds generated in association with the air flow such as exhaust gas in an air passing pipe from leaking outside. SOLUTION: In an air passage pipe 4, a rigidity reduced portion 12 comprising a pseudo cylindrical concave polyhedron is formed in a housing pipe 6. As a result, the pipe wall of the rigidity reduced portion 12 easily generates film vibrations by pressure vibrations acting from in the air passage pipe 4, and is able to thereby sufficiently transmit pressure vibrations via the pipe wall to a sound absorption material 8. In particular, if the relationship between the depth d of the unevenness of the surface of the pseudo cylindrical concave polyhedron and the thickness t of the member constituting the rigidity reduced portion 12 is d<√2t or d<2t, the member more flexibly deforms to easily generate significant film vibrations, whereby the pressure vibrations can be transmitted with higher efficiency to the sound absorption material 8 in solid-to-solid contact with the air passage pipe 4 to achieve the problem to be solved. COPYRIGHT: (C)2011,JPO&INPIT
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