| 摘要 |
PROBLEM TO BE SOLVED: To provide a suction duct capable of certainly establishing compatibly the noise prevention due to pulsation in the suction gas and the noise prevention due to the emitted sound while the manufacturing costs are suppressed. SOLUTION: The suction duct is a component made of a synthetic resin in a cylindrical form such that only one open end 10a to take in the atmosphere is enlarged diametrically and the diameter of the inside surface 10c extending in the longitudinal direction from the open end 10a till the other open end 10b is set in the same dimension. The line covering approximately the whole extent between the two open ends 10a and 10b of the suction duct 10 is furnished with a suction passage 16 consisting of an inner pipe 12 in cylindrical form to admit passage of the atmosphere and an outer pipe 14 installed on the whole peripheral zone of the inner pipe 12 with a certain gap C reserved. The inner pipe 12 of the suction passage 16 has a small wall thickness while the outer pipe 14 has a large wall thickness. Air is encapsulated in the gap C between the inner pipe 12 and outer pipe 14, and an air layer is formed. COPYRIGHT: (C)2004,JPO
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