GB358970A - Improvements relating to exhaust silencers - Google Patents

Abstract

358,970. Exhaust silencers. WILMAN, Z., 6, Rue de Bizerte, Paris. June 10, 1930, No. 17823. Convention date, Nov. 23, 1929. [Class 7 (ii).] The silencer consists of an outer cylinder 1b and a concentric inner cylinder open to atmosphere at both ends, two or more helical baffles between the cylinders forming helical conduits for cooling air and exhaust gas respectively, the exhaust gas conduit being of decreasing cross section in the direction of flow and communicating with the inner cylinder through apertures of progressively increasing cross section. In Fig. 1, two baffles 5, 11 are employed to form conduits for exhaust gas entering at 2, and air entering at 2a, the apertures being shown at 6. A portion of the gases may escape through apertures of increasing size into an auxiliary conduit 1c the outlet from which is controlled by a throttle 1d. Air passes through the inner cylinder due to the motion of the vehicle on which the silencer is mounted. In Fig. 2, four helical baffles are employed of which one pair b, c forms a passage of decreasing area for gases entering at 2, and another pair a, d a passage for gases entering at 2d. Between these pairs of baffles two helical passages are formed for air entering respectively at 2f and 2g. In a modification, the inner cylinder is of divergent form towards the outlet end, and the apertures 6 are formed with lips disposed in the direction of flow. The Specification as open to inspection under Sect. 91 (3) (a) describes also the construction shown in Fig. 1 (Cancelled), in which the exhaust pipe 2 is connected to a casing 1b enclosing a concentric tube 3 the inner end 4 of which is closed and of conical form. A single helical baffle 5 is provided, and the apertures of increasing size are shown at 6. A modified form is also described in which the helical baffle is duplicated in the reverse direction, a concentric apertured wall being located between the casing 1b and the inner cylinder 3. A further modified form is also described in which the silencer is traversed axially by a tube 7, Fig. 3 (Cancelled), one end of which communicates through apertures and a helical baffle 9, with the exhaust pipe 2, and the other end opens into the throat of a bi-conical tube 8 to produce an ejector action. The sound waves are reflected upwardly by surfaces 10. These constructions are not described in the Specification as accepted.