US2501767A - Muffler with internal side branch chamber - Google Patents

Description

March 1950 J. R. FLUOR ETAL 2,501,767

MUFFLER wrm INTERNAL SIDE BRANCH CHAMBER Filed March 1, 1948 INVENTORS. zYH/v Rose-e1- fizz/0e,

Fosv-Ee M. STEPHENS,

AQNOLD BHRTELS, glmeL Es NEWMAN, Y

141- T'ORNE'Y.

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UNITED STATES PATENT OFFICE MUFFLER WITH INTERNAL SIDE BRANCH CHAMBER John Robert Fluor, Foster M. Stephens, Arnold Bartels, and Charles Newman, Los Angeles, Calif., assignors to The Fluor Corporation, Ltd., Los Angeles, Calif., a corporation of California Application March 1, 1948, Serial No. 12,375

This invention has to do broadly with the elimination or dampening of pulsations in gas streams, and is concerned particularly, though typically, with the mufiiing of engine exhaust gas streams for the removal of pulsations predominating in the audible frequency range.

In the illustrative embodiment hereinafter described. the invention has adaptability to particular ad- .vantage for mufiiing the exhaust gas discharge from stationary engines, e. as used in compressor plant installations.

One of our major objects is to effect more efficient mufiiing of audible sound frequencies -by equipment characterized by its advantages from standpoints of production facility and substantially reduced cost in comparison with conventional apparatus of comparable efliciency,

In certain of its aspects the invention is directed to mufiiing equipment applicable to an engine in a building or room, and from which the exhaust gas is discharged to the outside, as within a stack shell. As adapted to such installations the invention contemplates a dual chamber arrangement in the nature of a pair of acoustical capacitances respectively inside and outside the engine room, and an elongated pipe interconnecting the chamber for series flow of the gas therethrough, and having characteristics of an acoustical inductance.

of employing the vertical outside stack shell as a second capacitance.

A further important feature and object of the invention is the use in conjunction with an acoustical capacitance chamber, and specifically with each of the chambers in the above mentioned dual chambers system, of a communicating closed space or chamber itself serving to cancel out gas stream pulsations by reason oiits individual characteristics as an acoustical filter. In this respect. the invention contemplates use 01 a closed chamber having a restricted inlet communication with a secondary chamber, the gas surgin into and out of the --closed chamber through the restricted inlet, and

the chamber and inlet being so proportioned as to form an acoustical filter having a resonant frequency corresponding substantially to the dominating pulsation The above mentioned as well as various additional features and objects of the invention will be understood to better advantage from the As will appear,. the invention incorporates the practical feature frequency in the gas 9 Claims. (Cl. 181--59) following detailed description of an illustrative 2 embodiment shown generally in section by the accompanying drawing.

Referring to the drawing, an internal combustion engine, diagrammatically indicated at m, is shown to be contained in a room R, with the exhaust gas discharge conducted through the room wall H to the stack assembly l2 at the outside. Exhaust gases are discharged from the engine through a pipe Iii into a first chamber assembly generally indicated at M, and thence through an elongated pipe iii to a second chamber arrangement I6 in the stack assembly [2.

The exhaust pipe l3 communicates by way of a perforated tubular section I! with a closed chamber I8, the latter being closed in the sense that exhaust gases can enter and leave the chamber only by surging flow through a restricted inlet. Preferably, such inlet is formed by a perforated plate I9, the total apertured area of which is such as to restrict the exhaust gas flow into chamber l8. This closed chamber, together with restricted inlet, constitutes essentially an acoustical filter which may be designed, by proportioning the chamber volume and the effective restriction to gas flow presented by the perforated plate i 9, as to have a resonant frequency (i. e., frequency of gas surge into and out of the chamber) corresponding substantially to the frequency of the dominating pulsations in the gas stream. Thus the effect of the chamber I8 is to accomplish an initial canceling out of pulsation effects, particularly while functioning in conjunction with a second chamber 2i! having restricted communication with the exhaust gas feed through the perforated tubular section l1.

Chamber 20 is formed by an outer shell 2| axially aligned with the inner chamber l8 and having an end closure 22 about the inlet l3. The forward end of shell 2! is tapered at 23 to connect with the elongated pipe I 5. The latter in turn is connected at 24 with an enlarged pipe section 25 having restricted communication through perforated plate 25 with chamber 21, the structural and functional characteristics of which are similar to those previously described with reference to chamber l8. Pipe 25 has restricted communication through the perforated tubular section 28 with the enlarged chamber 29 in the vertically extending stack shell 38, the latter having a bottom closure 3! and a convergent upper end 32 containing an outlet which may be formed by pipe 33 having a perforated section 34.

Where it may be desirable that the muffling assembly be air-cooled, or the energy of the exhaust gas stream utilized to Withdraw air from the engine room R, provision may be made for inducing air flow from the room by the exhaust gas discharge from the outlet 33. For this purpose, shell 38 may be contained within and annularly spaced from the outer shell 35 having a convergent head 36 and stack 31 forming a Venturi throat, the exhaust gas discharge into which from outlet 33 induces air flow through the inter-shell space 38. At this point it may be mentioned that because of the exceptionally high degree to which the mufiiing system acts to remove the exhaust gas stream pulsations, the air displacement efficiency, i. e., the ratio of induced air to exhaust gas, is exceptionally high. The air flow is induced from the engine room through the flared inlet 40 and conduit M annularly spaced about the pipe I5 and connecting at '52 with the shell 35.

In the operation of the muilling system, gas stream pulsations initially are subjected to the nullifying or canceling eilect of the acoustical filter system consisting of the chambers 18 and 2n and the restrictions presented by the perforated elements H and 19. The exhaust gas stream then passes through the extended in ductance pipe l5 wherein its flow is restricted with relation. to chambers 20 and 25. Any remaining pulsations in the gas stream then be come subjected to canceling out by the acoustical filter system presented by chambers 21 and 29,

and the gas passage restrictions presented by the perforated areas 26 and 28.

We claim:

1. Apparatus for eliminating gas stream pulsations comprising an outer shell having a gas out let, an inner shell extending longitudinally within and spaced from said outer shell and having a closed end toward said outlet, an inlet pipe connccted to said shells, and means forming a plurality of restrictions in the end of said inner chamber toward the inlet pipe and through which the inlet surges into and out of the inner chamber and flows into said outer chamber to the outlet.

2. Apparatus for eliminating gas stream pulsations comprising an outer shell having a tapered end forming a gas outlet, an inner shell extending longitudinally within and spaced from said outer shell and having a closed end toward said outlet, an inlet pipe connected to said shells, and means forming a plurality of restrictions in the end of said inner chamber toward. the inlet pipe and through which the inlet gas surges into and W out of the inner chamber and flows intosaid outer chamber to the outlet.

3. Apparatus for eliminating gas stream pulsations comprising an outer shell. having a gas outlet, an inner shell extending longitudinally within and spaced from said outer shell and having a closed end toward said outlet, an inlet pipe connected to said shells, and a perforated plate forming the end of said inner chamber toward the inlet pipe and through which the inlet gas surges into and out of the inner chamber and flows into said outer chamber to the outlet.

4.. Apparatus. for eliminating gas stream pulsations comprising an outer shell having a gas outlet, an inner shell extending longitudinally within and spaced from said outer shell and having a closed end toward said outlet, an inlet pipe connected to said shells, means forming a plurality of restrictions in the end of said inner chamber" toward the inlet pipe and through which the inlet gas surges into and out of the inner chamber and flows into said outer chamber to the outlet, and means forming a plurality of restrictions at the inlet side of the first mentioned restrictions and through which the gas passes in flowing outwardly into said outer shell.

5. Apparatus for eliminating gas stream pulsations comprising an outer shell having a gas outlet, an inner shell extending longitudinally within and spaced from said outer shell and having a. closed end toward said outlet, an inlet pipe connected to said shells, and means forming a plurality of restrictions in the end of said inner chamber toward the inlet pipe and through which the inlet gas surges into and out of the inner chamber and flows into said outer chamber to the outlet, said inlet pipe being a perforated section through which the gas at the inlet side of the first mentioned restrictions passes in flowing outward- 1y into said outer shell.

6. Apparatus for eliminating gas stream pulsations, comprising a pair of shell assemblies through which the gas flows in series, each of said assemblies comprising an outer shell having a gas outlet, an inner shell extending longitudinally within and spaced from said outer shell and having a closed end toward said outlet, an inlet pipe connected to said shells, means forming a plurality of restrictions in the end of said inner chamber toward the inlet pipe and through which the inlet gas surges into and out of the inner chamber and flows into said outer chamber to the outlet, the inlet pipe connecting with the shells of the second shell assembly leading from the gas outlet of the outer shell of the first assembly.

7. Apparatus as claimed in claim 6, in which said inlet pipe connecting with the shells of the second shell assembly is elongated and has considerably smaller diameter than said outer shells.

8. Apparatus as claimed in claim 6, in which said inlet pipe connecting with the shells of the second shell assembly has enlarging tapered connections with the second shell assembly and with the gas outlet of the outer shell of the first assembly.

9. Apparatus as claimed in claim 6, in whic the outer shell of the second shell assembly is a vertically positioned stack located remote from the first shell assembly.

JOHN ROBERT FLUOR. FOSTER M. STEPHENS. ARNOLD BARTELS. CHARLES NEWMAN.

REFERENCES CITED The following references are of record in the file oi thispatent:

UNITED STATES PATENTS

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