| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise by providing a bulkhead for a cavity position corresponding to odd-number times of a specific times of a wavelength of resonance noise corresponding to longitudinal of a compartment or a volume of a luggage compartment, from an opening communicating with the compartment or the luggage compartment formed at one end of external equipment. SOLUTION: A pipe 12 is engaged with a circular opening 11 formed on the bottom surface of an anchor portion 19 of the front end of a roof rail(RR) through an opening 15a of a seal material 15, its top portion and bottom portion are respectively communicated with a cavity portion 10a of the RR10 and the compartment, and substantial opening of the RR10 is the top portion of the pipe 12. Acoustic standing wave with resonance frequency whose half wavelength is longitudinal length of the compartment occurs in the compartment of a wagon-type vehicle, a partitioning wall 17 is formed in the cavity portion 10a at a position far away from the bottom of the pipe 12 by 1/4 wavelength of resonance noise. Thus, a side-branch-type muffler with 1/4 wavelength is constituted in the RR10, and the opening 11 is positioned near an antinode of resonance mode. This can reduce noise by cavity resonance with 1/4 wavelength.
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