| 摘要 |
773,227. Silencers for gaseous currents. COOPER'S MECHANICAL JOINTS, Ltd., and STREETE, C. M. Sept. 12, 1955 [Sept. 21, 1954], No. 27320/54. Class 7 (2): A duct 12 having at all transverse planes along a substantial length thereof a crosssectional area which is small in relation to the peripheral length of the duct is substantially wholly surrounded by a mass of fibrous or porous sound-absorbing material 17 contained in a casing 1, and is arranged to receive the gases at one end from an expansion chamber 7 to deliver at the other end into a secondary expansion chamber 13 from which the gases are discharged through a comparatively narrow outlet. As shown, the duct 12 is formed by a perforated, tubular member the ends of which fit over flanges provided by slots of the same configuration as that of the duct and formed in perforated plates 8, 11, the casing 1 being of elliptical, circular or rectangular cross-section and comprising two parts welded together along flanges 2. The expansion chambers 7, 13 are formed between the ends of the casing and plates 8, 11. The annular space between the duct and the casing is packed with glass wool 17 to a density of four and a half to five pounds per cubic foot, the glass wool being initially packed in paper or scrim to facilitate insertion into the casing, or bonded with phenolic resin or a starch compound and moulded to fit between the casing and the duct; alternatively, the soundabsorbing material may comprise metal, e.g. brass, swarf, steel wool or sintered metals such as porous aluminium. A member 15 of angular cross-section secured to the duct 12 prevents the sound-absorbing material from being blown, by the gas passing through the perforations in the plate 8, to the rear of the silencer. The duct may be flat, cruciform or annular, and divided into several passages in parallel each surrounded by sound-absorbent material ; as shown in Fig. 3, the duct is divided by a perforated plate 14, or two such plates spaced apart by a distance equal to that between the flat faces of the duct are used, the space between the plates being filled with soundabsorbing material and covered at each end by perforated guards. A fishtail may be attached to the outlet pipe 4; the inlet pipe 3 fits inside a pipe 5 secured by a bracket 6 to the casing 1.
|
