| 摘要 |
PROBLEM TO BE SOLVED: To provide a muffler requiring no antiphase sound source, excellent in environment resistance and durability, and minimized in passage loss. SOLUTION: The sound flow directing from the upper stream of a main pipe 1 to the lower stream is branched into two flows in the inlet of a pipe 5, one is carried through the pipe 5 having a length L1, a pipe 7 having a length L2, and a pipe 9 having a length L3, and the other is carried through the part 13 having a length L of the main pipe 1, and they are converged together in the outlet of the pipe 9. When the wavelength of main noise isλ, the relation of L1+L2+L3-L=λ/2 is established. Therefore, the phase of the main noise (and the harmonic noise of odd-orders of the main noise) is differed by 180 deg. between the main pipe 1 and the pipe 9 in the converged part, so that the main noise and the harmonic noise of odd-orders of the main noise are erased.
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