GB1017912A - Improvements in or relating to a sound attenuating gas pipe - Google Patents

Abstract

1,017,912. Exhaust silencers. ARVIN INDUSTRIES Inc. May 17, 1963, No. 19833/63. Heading F1B. A sound attenuating gas pipe comprises an outer pipe 10, Fig. 2 carrying therein an inner pipe 16 providing a main gas flow passage and beads 17, 18, axially spaced along the gas pipe to form axiallyspaced resonator chambers 19 interposed between the pipes 10, 16 and the throats 20, openings to the throats being formed in the inner pipe at 22 and in the bead 17 at 23. In a modification a dam, comprising a weld fillet on a drawn section of the inner pipe, is interposed in the throat between the openings 22, 23, to provide a longer path thereby attenuating lower sound wave frequencies. The beads may be arranged to project inwardly from the outer pipe or as a group of helical beads on the inner pipe, having a closed turn at one end and an open turn at the other end. In another embodiment, two adjacent throats may be formed by a group of three beads on the inner pipe, and one of the throats in each group may be modified by the provision of a dam. In further modifications the inner and outer are spaced by pairs of rings have a Z-shaped cross-section, or rings having inwardly or outwardly directed channels, or by inwardly-directed beads on the outer pipe which are surrounded by an annular ring. In other embodiments the inner pipe has a series of axially-spaced projections having formed beads closed at one end by the body of the projection and opening out at the other end into a resonance chamber or the inner pipe may be formed from sections having integral projections at their ends, the spaces between adjacent pipe sections forming apertures leading to the throats.