Patent GB-1400594-A (GB)
Title: Muffler with resilient exterior
IPC: F01N13/16
Filed: 1972-09-29
Abstract: 1400594 Gas flow muffler DOW CORNING CORP 29 Sept 1972 45038/72 Heading F1B A muffler, for attachment to a high velocity gas device, comprises a gas impervious sheath defining a container, a frame supporting the sheath and consisting of frame members having edge surfaces adapted to contact the sheath to close the container and gas entry means on the frame, means for attaching the frame to the gas device, the sheath being of a resilient material adapted to be displaced from the frame member edges under gas-pressure to pass gas from the container defined by the sheath. Fig. 1 shows a muffler for use with a small (e.g. 0.049 cu. in. capacity) engine and consists of a rectangular section finned metal tube 22 having an open end 29 which is attached to the exhaust port of the engine and an integral extension comprising two side walls 41 joined at their free ends by an end-wall 42. A flexible sheath 44 e.g. of silicone rubber, surrounds the frame members and is preferably adhered to the tube 22. An intermediate baffle plate 53 extends between the side walls and includes a port, the effective area of which can be varied by a sliding plate 61. Gas entering the tube 22 lifts the sheath away from the edges of the baffle 53 and the end-wall 42 to escape to atmosphere. The sliding plate 61 is positioned to tune the muffler to its basic resonance. The sheath resilience may be modified by laminating to its top and bottom walls 45 and 46 respectively a layer of stretch fabric 68. A further layer of foamed silicone rubber may be applied over the fabric. Alternatively the fabric may be embedded within the thickness of the sheath. Fig. 7 (not shown) shows an arrangement in which two rectangular section tubes are clamped to the outside of a cylinder by a sheath (87) extending around the outer ends of the tubes. Fig. 8 shows a construction which is applied to an airmotor operated hand tool and which consists of two semi-circular shells 108 and 109 encircled by a sheath 129 which engages the edges of side walls 111 and 112 and intermediate ribs 127. Air leaves the motor through ports 124 and enters an inner chamber 116, from which it passes by a port 121 to a first outer chamber 133. The gas displaces the sheath to pass over the edge of the first intermediate rib to a chamber 134, over the second intermediate rib to a chamber 135, and over the edge of the side wall 111 to atmosphere. Fig. 11 shows a construction suitable for a large vehicle engine. The muffler consists of a bottom plate 182 having a gas inlet 183, connected by angle iron corner pieces 178 to a top plate 181 having a gas outlet 201. The sheath comprises four panels 173, 174, 175, 176. The muffler has imperforate partitions 185, 197, 198 and 199, each compartment being sub-divided by diagonal walls 193, 194, 195 and 196. Exhaust gas passes around the edge of each partition successively to reach the outlet 210. Fig. 13 shows a construction in which exhaust gas from a vehicle engine enters a manifold 221 which communicates with four muffler assemblies 215, 216, 217 and 218 each consisting of resilient side panels 222 and 223 supported by a framework including intermediate baffles 231 and 232. Gas enters through a port 235, passes around the edges of the baffles and exhausts to atmosphere by lifting the panels away from the edges of a top member. Fig. 16 shows a vehicle engine air intake silencer. A sheath 302 surrounds a framework including end-plates 304 and 307 and intermediate baffles 305. Air enters a port 312 and passes between the sheath and the edges of the baffles to an outlet 315. A casing 309 surrounds the sheath and is open to the engine suction so that a depression exists around the sheath. In any of the constructions described one of the baffles may be adjustable in a direction parallel to the gas flow-path to tune the muffler to resonance.