Patent GB-789180-A (GB)
Title: Improvements in or relating to combined gas filters and silencers
IPC: F02M35/14
Filed: 1955-05-26
Abstract: 789,180. Silencers for gaseous currents; treating charges. COOPERS MECHANICAL JOINTS, Ltd:, and STREETE, C. M. April 27, 1956 [May 26, 1955; Aug. 10, 1955], Nos. 15273/55 and 23104/55. Class 7(2) [Also. in Group XXVIII] In a combined silencer and gas filter comprising a flat casing 1, Figs. 1 and 2, presenting in plan a comparatively large area and in side and end elevations comparatively small areas, an inlet duct 11 extends along the casing from a point at or close to one edge thereof, as viewed in plan, to a point close to the opposite edge thereof, or extends along the major portion of the distance between such edges, and receives gas at one end and delivers the gas into the casing at the other end, there being an outlet 18 arranged to discharge the gas through the wall of the casing in a direction substantially at right angles to the gas stream in the duct. The latter is free along the length thereof from any bend that would alter the direction of flow of the gas through the duct. Prior to passing through the outlet, the gas passes through a filter 15 disposed within the casing. As shown in Figs. 1 and 2, the metal casing 1 is divided by a partition 4 into chambers 6, 7 and the straight metal pipe 11 having a flared inlet 11a communicates with these chambers by way of holes 11b, 11c. A cylindrical filter element 15 having a corrugated or pleated wall consisting of galvanized wire mesh or paper wetted with oil is secured to a cover plate 14 and by staples to a perforated cylinder 16 also secured to the cover plate; the element is pressed tightly against the bottom of the casing by a nut 23 screwed on to a rod 21 and clamping the plate 14 in position. The end wall 12 of the casing is arcuate in form so that air induced to flow through the pipe 11 sweeps around that wall and circulates about the filter before passing through the latter to the outlet pipe 18, impurities carried into the casing being thrown out of the stream of air by centrifugal action and deposited in the chamber 6. The pipe 18 is split for clamping the casing on to the down tube of a carburetter with an intervening rubber bush 25, and the casing is supported by a member bolted to a bush 26. A flanged nipple 29 welded in an opening 27 is connected by a flexible tube to a breather hole in the crankcase or rocker cover, or both, of the engine. The pipe 11 may be formed by two concentric walls the annular space between which is closed at the inlet end of the pipe, and the inner wall having small perforations in lieu of the holes 11b, 11c. In a modification, the casing 33, Figs. 4 and 6, is rectangular in form and includes two parallel, semi-circular, air inlet ducts 48, 49 having flared inlet ends and extending lengthwise of and on opposite sides of the casing, the air from the ducts passing through ports 46, 47 situated at opposite corners of the casing; the ducts may have portions which increase in cross-sectional area towards the ports. In another modification, the filter which comprises a mass 72, Fig. 11, of woven or knitted wire contained between inner and outer cylindrical members 69, 70, is surrounded by an oil bath 66 filled to the level of a ridge 75, air from ducts 58 of increasing cross-sectional area entering the casing 62 through ports 77 and passing successively through the oil bath and the filter and then being discharged through the outlet duct 61. In a further modification, a rectangular casing 81, Fig. 14, contains a filter element consisting of a zig-zag layer of wire gauze 85 and a layer of felt 86, or of synthetic resin-bonded paper, the straight edges of the filter being tucked under clips 87, 88 secured to the casing, and felt seals being provided at the ziz-zag edges adjacent the walls of the casing; the air inlet ducts 93, 94 are arranged on top of the casing. In a still further modification, the outlet pipe 96, Fig. 15, forms part of a cover plate 97 located in the lower wall 98 of the casing 106 and secured in position by a spider 102 to which. the pleated filter 109 is attached. The casing is sub-divided by a partition 112 and has an air inlet pipe as shown in Fig. 1; alternatively, the inlet pipes are as shown in Fig. 14, the partition being omitted.