GB623098A - Improvements in exhaust silencers for internal combustion engines - Google Patents

Abstract

623,098. Exhaust-silencers. DEHN, S. G. (Fluor Corporation, Ltd.). Dec. 23, 1946, No. 37757. [Class 7 (ii)] In an internal combustion engine silencer for dampening pulsations produced in an exhaust gas stream, there is provided a pair of relatively large pulsation-absorbing chambers through which the gas flows in series, and a circular cross-section conduit forming an acoustical inductance passage interconnecting the chambers, the minimum volume of each of the chambers and the dimensions of the passage having predetermined values substantially in accordance with the following equation : LV/R<SP>2</SP> C<SP>2</SP>/78.674F<SP>2</SP> wherein L=Length of the passage in inches R=Radius of the passage in inches. V=Minimum corresponding or common volume of the chambers in cubic inches. C=Velocity in feet per minute of sound in the gas. F=A selected value for the fundamental frequency per second of pulsations created in the gas stream. A cylindrical casing 11, Fig. 1, is divided by a transverse partition 12 into two chambers 13, 14 interconnected by one or more conduits 18. The exhaust gas enters the chamber 13 by an inlet pipe 15 and discharges from the chamber 14 by an outlet pipe 16, after taking a sinuous path. The casing 11 may be contained within an air jacket 21, the air being drawn through a space 22 by the induction action of the gases discharging from the outlet pipe 16. In a modification, Fig. 3, a centrally-disposed air conduit 34 extends throughout the length of the casing 30, whilst an exhaust inlet pipe 38, which is positioned within the conduit 34, has its other end situated in the wall of the latter to enable the exhaust gas to discharge opposite a baffle 46 into a lefthand chamber 31. The latter is formed in the cylindrical casing by a central transverse partition 33, from which by means of interconnecting conduits 45 disposed externally of conduit 34 the exhaust is led into the second chamber 32. The walls of the central air conduit 34 have two diametrically opposed openings in the second chamber 32 which by means of piping communicate with a common exhaust outlet pipe 42 located within the right hand end of central air conduit 34. The outer end of the exhaust outlet pipe 42 discharges into a venturi 36, that is a continuation of the central air conduit 34, wherein the air and exhaust gas are discharged together. In a further modification, the casing 30 is enclosed in an air jacket through which air travels from the outlet side of the silencer before being admitted into the central air conduit 34 near the inlet of the latter into the casing 30. Under these circumstances the main air inlet to conduit 34 may be c'osed.