US2617490A - Baffle type muffler - Google Patents

Description

w. c. DIEHL, JR 2,617,490

BAFFLE TYPE MUFFLER 2 SHEETS-SHEET 1 Nov. 11, 1952 Filed Jan. 10, 1951 'INVENTOR.

1377/1111 K112i], fi'

flrrcmwf) HI H NOV. 11, 1952 w c, m JR 2,617,490

BAFFLE TYPE MUFFLER Filed Jan. 10 1951 2 Sl-iEETS-SHEET 2 INVENTOR.

William fjiel fi Patented Nov. 11, 1952 BAFFLE TYPE MUFFLER William C. Diehl, Jr., North Bergen, N. J., as-

signor to Columbia Truck & Equipment Sales, Inc., New York, N. Y., a corporation of New York Application January 10, 1951, Serial No. 205,347

9 Claims.

This invention relates to an exhaust gas silencer and scrubber. In particular, the invention relates to an exhaust gas silencer adapted to reduce to a minimum the noise caused by the exhaust of an internal combustion engine and which at the same time minimizes back pressure on the engine.

The performance of exhaust silencers or mufflers heretofore employed has been a compromise between a maximum acceptable noise level and a minimum acceptable back pressure. The advent of high powered, high speed internal combustion engines has aggravated the exhaust noise problem; yet, no silencers have been afiorded which eliminate or reduce such noise to an unobjectionable degree and at the same time cause negligible back pressure in the combustion engine.

The exhaust from an internal combustion engine is in effect a continuous series of high pressure, high temperature and high velocity shock waves of gas, which in order to eliminate the objectionable noise associated with the discharge of such gas stream must be converted into a low pressure, relatively 0001, low velocity gas stream as it is being discharged from the exhaust system. The reduction of the noise factor in exhaust discharge can be accomplished by cooling, wave tuning, controlled turbulence, wave scraping, cushioning and swirling of the exhaust stream. However, heretofore the silencers that have been known to the industry have employed only two, or at the most three, of such expedients.

It is, therefore, one of the objects of this invention to provide an exhaust silencer which will reduce to a minimum the velocity, temperature and pressure of the exhaust gas stream being discharged from an internal combustion engine. To the end that this general objective may be attained, it is the purpose of this invention to provide a silencer in which an exhaust gas stream may be cooled to a low temperature whereby the pressure and the resultant velocity of the stream may be reduced, wherein tuning of the shock waves is achieved, wherein the turbulence of the gas stream is controlled, and wherein provision is made for wave scraping and cushioning as the exhaust gases pass through the silencer. A

silencer is thereby provided in which substantially all of the known processes are employed for reducing the ultimate noise caused by the normal discharge of the exhaust stream into the open atmosphere.

It is a specific object of the invention to obtain a maximum cooling of the gases as they pass through the silencer. This objective is attained by designing the silencer in such manner as to cause the gas passing therethrough to follow a relatively long, outer, air cooled, peripheral wall of the silencing unit where maximum cooling may be attained.

It is a further specific object of the invention to provide for wave tuning of the exhaust gases as they pass through the silencer. This objective is attained by incorporating in the silencer one or more cushioning chambers or wave traps which absorb and store portions of the peak pressure gases until the peak of the shock wave passes and then release such stored portions during the passage of the low pressure gases through the area. This device serves to smooth the pressure differential between the high and low portions of the shock wave.

It is a further specific object of the invention to provide a gas passage through the silencer which is of relatively large area, so that in the passage of the exhaust gases through such passages the pressure of the stream will be dissipated and velocity of the stream will be decreased.

It is a further specific object of the invention to provide a silencer in which there is only unidirectional flow of the gases so as to avoid restrictive turbulence which creates back pressure.

It is a further object of the invention to provide means for dampening the shock wave and for causing non-restrictive or controlled turbulence in the flow of the gas stream through the silencer unit. This objective is achieved by providing cushioning chambers in the silencer unit in which peak wave pressure of the gas stream is dissipated.

It is a further object of the invention to provide a, gas entrance chamber which is of large volume and in which the gases are given a vortex movement, thereby avoiding restriction to the gas stream flow, while at the same time subjecting the stream to maximum cooling by contact with outer heat dissipating surfaces of the silencer.

It is still a further ob ect of the invention to provide a silencer having therein a suitable chamber for holding an exhaust gas treating substance in such manner as to insure the intimate contact of the gas stream and the treating substance, so that the exhaust gas may be deodorized and the noxious constituents thereof may be neutralized before the gas is discharged into the open atmosphere.

These and other objectives of the invention will appear as the detailed description of the invention proceeds when read in light of the drawings forming a part of this application, and in which drawings:

Figure 1 is a side elevational view of the silencer with portions broken away to show underlying structure; and

Figure 2 is a cross-sectional view of the silencer on line 2-72 01 Figure 1.

The silencer is .a generallyelongated casing having therein a plurality of interconnecting chambers constituting a single, continuous path for engine exhaust gases on their way to the atmosphere. One end of the silencer casing is provided with a flange ill which serves to separate or seal off the several chambers of the silencer, and serves also as :a means through which an exhaust pipe l2 may be connected to the silencer for conducting highpressure exhaust gases thereto. The exhaust pipe l2 discharges into a generally circular inlet chamber'l l, which extends throughout the axial length of the silencer. The wallof the; inlet chamber ll is exposed to .theatmosphere throughout is major diameter and thereby provides fora maximum cooling of the gases received therein. Because of the generally circular cross-sectional contour of the inlet chamber, coupled with a tangential outlet-therefrom there is immediately imparted to-theincoming gasesa swirling motion which .causes.the.hot,.high pressure, high velocity gases to contact the outer, air"cooled,.periphera1 wall of the chamberwhich divests thesegases of much of-their heat by conduction through the atmos ;.pherically .cooled wall of the inlet chamber. From.theinletchamber l l .the partially cooled .gases enter one or. more cooling or dilfusing wings which are inthe-shapeofa hol-low, axially disposed fin extending generally-iradially in respect to the longitudinal center line or" :the v silencer. .Onesuch wing -is'provided by a pair of i spaced :side walls joined by an end wall. These walls are in contact with the atmosphere and provide a .long cooling-ipath for the-exhaust-gases in contact therewith.

Specifically, the entrance v chamber i l dischargessin-to' azcooling and diffusing wing lit, by way-f a'tangentiall-y disposed throat it, which extends along-the length-of the silencer structure. -T-h-us,-the vertically"movinggases within'the entrance chamber it move without substantial --turbulence from the entrance chamber ithroug-h'the throat 18 and into the cooling and diffusing wing It.

For the purposeof insuring c'ontact'ofa maxi- ;mum --amountof gas with the outer atmospherically cooled walls of the wing I6, there is provided in the wings guide baffle which serves this :purpose. nccordingly there isproVideQadividingbafile=2ll which is affixed to the Wall-2i of vthe" silencer discharge chamberand in such posiwtion as to lie substantially in the geometric center of the cooling and vdiffusing wing it and in a substantiall-yradialposition in respect to the center line of the silencer. The dividing bafiie ZU-isa solid plate, preferably-of imperiorate sheet -metal, which-extends throughout the axial length :of -the silencer.

Within 'the-wing l-fi is provided ashock wave scraping and cushioning structure which is designed to modify the nature-of the *gas stream as it passesthroughthe silencer. Disposed on eachv "side of ther-bafileflh and in a somewhat angular relation thereto, are a pair of perforated primary baflie-orcushion plates Handed. Between the ,pri-mary-ba-file plate 22 and the solid baffie plate -20 is a" secondary perforated baffle or cushion .of the respective bafiles, through which gases passing about the wing plate 2%, and between the primary baflle 24 and the solid baflle plate Ed is a secondary perforated bafile or cushion plate 2%. By this structure there is provided on each side of the solid baifie plate 253 a primary and a secondary pressure chamber, i. e., a primary pressure chamber is formed between the plates 22 and26on the one hand and between the plates 2d and 23 on the other hand. A secondary pressure chamber is formed between the plates 28 and 2% on the one hand, and between the plates 28 and 23 on the other hand.

The wing structure It has a flattened portion 36 which, together with the outer converged ends provides a channel structure may :flow from the inlet side of the structure to the discharge side of the structure.

A perforated baifie strip 32 is disposed along the wall-.39 and in spaced relation thereto, whereby a further cushioning chamber is provided at the area in which the exhaust gases pass from the entrance side of-the wing tothe discharge side of I the wing.

Theperforaticns in the plates 22 and 24mmprise substantially one-half th entire .areaof these plates, whereas the perforations in the plates 26 and 28 constitute onlythir-ty .per cent of the area of these latter plates.

Asthe exhaust gas passes from the entrance chamber i l, throughthe discharge throat [8, it

.flows along the surface of the shell constituting the wing it and the primarycushioning plate 22.

During a pulsation of. high pressure, a small portion of thegas in its passage enters the primary cushioning chamber formed between the cushion plates 22 and This absorbs and stores-some of the energy-of the high pressure pulsations and permits-the remaining .portionof thegas toproceed-in its passage through the cooling and diffusing wing. The gas which passes on in normal course is scraped by theperforations inthe cushion plate-zland this imparts to such gas a rolling action in the direction of-fiow. Therolling action of the passing gas causesa-maximum' of hot gas to come into contact with theouter shell of the coolingand diffusing wing 15, thus providing a maximum cooling efiect.

After the partially 'reduced' pressure wave of flowing gas streamhas passed on, the entrained portion of the pulse charge in the primary cushion chamber between cushion plates '22 and 26 has a primary and asecondary'wavetrap disposed on each side of thedividing bafile 20, the dampening process applied to the'exhaust stream is performedtwiceas theexhaust stream'ip'asses through'the cooling and diffusing wing it. As the gas stream passes along the dischargeside of the cooling and diffusing wing, thedampening and cooling process is precisely the same as that eifected on the entrance side of the wing with the exception that the pressure'and temperatures'on the discharge side are lower by-virtue of the treatment received by "the gases along the entrance side of the wing. The gases from the discharge side of the cooling and diffusing wing IE may be discharged into a generally axial- 1y disposed discharge chamber 34 which is closed at one end by the end flange it, but for which discharge to the atmosphere is provided through an opposite end flange 36. Provision is made for attaching an exhaust pipe 33 to the end flange 36, whereby gases treated within the silencer may be discharged to the atmosphere.

In its preferred form the silencer herein embodies a plurality of wings such as the wing l6, each having a baflie and a plurality of baflle or cushion plates, such as the plates 22, 24, 26 and 28. Accordingly, in the drawing there is shown a structure in which four such cooling and diffusing Wings are provided. When a plurality of such cooling and diffusing wings are employed, each wing following the entrance chamber 14 discharges into a succeeding wing. Thus, in the illustrated embodiment of the invention, the wing I6 is adapted to discharge its gases into a wing 31, and the wing 37 is designed to discharge the stream of exhaust gases into a Wing 39. Finally, the wing 39 discharges its gases into a wing 40 which is provided with an axially disposed passage forming a discharge throat 42, through which the exhaust gases are adapted to pass into the outlet chamber 34.

It will be appreciated that but for the outlet throat 42 the wings 31, 39 and 40 are identical with the first cooling and diffusing wing it. Each of these wings constitute an axially disposed chamber of hollow, fin-like form in which the cushioning chambers are provided by the respective baflie or cushioning plates referred to in connection with the initial cooling and diffusing wing H5.

The discharge throat 42 is tangentially disposed with respect to the axis of the discharge chamber 34, so that the low pressure gas stream enters the chamber in a whirling stream which finally tends to dissipate the last vestige of shock wave pressure therein. In this regard it is to be noted that the cooling and wave tuning action in each of the cooling and diffusing wings successively cools and dampens the pulsating gas stream as it passes through the silencer, so that by the time the exhaust gases have reached the discharge chamber 34 they are substantially cooled and at such low pressure that they may be discharged through the exhaust pipe 38 with-- out objectionable noise. In this regard it is to be noted that the bafiles 32 carried by the cooling and diffusing wings serve substantially to reduce resonance in the silencer shell so that the overall operation of the silencing device is so effective as to reduce the exhaust noises to almost an inaudible minimum.

In order that the exhaust gases may be subject to a scrubbing action for the removal of odors and noxious gas constituents, there is provided along the line of gas flow a reservoir 42 in which a suitable reagent may be placed by which the obnoxious characteristics of exhaust gas may be neutralized.

In the specific embodiment of the invention herein illustrated, the reservoir 42 is provided at the junction of two of the cooling and diffusing wings. As illustrated in the drawings, it is located between the wings 3'1 and 39, and it is formed by bending the outer shell of the silencer to provide an outwardly extending trough in which the reagent may be deposited. This trough extends axially along the length of the silencer so that the entire width of the gas stream may be subject to its influence. A perforated plate 44 may constitute a closure for the reservoir, and in connection therewith a downwardly extending bafile 46 is provided for insuring adequate contact between the flowing gas stream and the reagent in the reservoir.

The invention herein has been described with reference to a specific form thereof, but from the exposition of the principles embodied, it will be possible for those skilled in the art to vary the specific structure; and it is the purpose of this application to cover within the scope of the claims thereof such modifications as may be suggested by the specification.

What is claimed is 1. An exhaust silencer for internal combustion engines and the like, comprising walls forming an elongate entrance chamber of predetermined length and having at one end thereof an entrance opening for a stream of exhaust gases to be silenced, walls forming a discharge chamber disposed in substantially parallel relation to said entrance chamber, said entrance and discharge chambers being substantially coextensive in the direction of said predetermined length, and said discharge chamber having an exit opening for the flow of gases from said silencer at the end thereof opposite that end of the silencer at which gases are adapted to be supplied to said entrance chamber, a casing rigidly mounted with respect to all said Walls and including a pair of spaced walls and a center baffie jointly forming a gas cooling wing disposed in substantially radial relation in respect to said discharge chamber and substantially coextensive therewith in the direction of said predetermined length, said center baiiie being mounted on a wall forming said discharge chamber, a passage formed between one of said pair of spaced walls and said center bafiie and coextensive with said predetermined length from said entrance chamber to said cooling wing on one side of the center bailie thereof, and a passage formed by some of said walls and said casing and coextensive with said predetermined length and extending from that portion of said cooling wing on the other side of the center baffle thereof to said discharge chamber.

2. An exhaust silencer in accordance with claim 1, wherein said passage from said entrance chamber to said cooling wing communicates tangentially with said entrance chamber.

3. An exhaus-u silencer in accordance with claim 1, wherein said passage from said cooling wing to said discharge chamber communicates tangentially with said discharge chamber.

4. An exhaust silencer for internal combustion engines and the like, comprising walls forming an elongate entrance chamber of predetermined length and having at one end thereof an entrance opening for a stream of exhaust gases to be silenced, walls forming a discharge chamber disposed in substantially parallel relation to said entrance chamber, said entrance and discharge chambers being substantially coextensive in the direction of said predetermined length, and said discharge chamber having an exit opening for the flow of gases from said silencer at the end thereof opposite that end of the silencer at which gases are adapted to be supplied to said entrance chamber, a casing rigidly mounted with respect to all said walls and forming therewith a plurality of cooling wings each substantially coextensive with said predetermined length and all '7 disposed radially of said discharge chamber, each of said cooling wings being formed by a pair of spaced walls forming a part of said casing and joined together at their radial outer edges, a center baiiie secured to said walls forming said discharge chamber and cooperating with the walls of said casing in providing each of said wings respectively, a passage formed between one of said pair of spaced walls and the center bafiie aforesaid jointly forming a first of said cooling wings and coextensive with said predetermined length from said entrance chamber 'to the first of said cooling wings on one side of the center baffle thereof, a passage formed by some of said walls and said casing and coextensive with said predetermined length and extending from that portion of a last of said cooling wings on the other side of the center bafile thereof to said discharge, chamber, and passage means formed by portions of said discharge chamber forming walls and said casing and serially connecting the adjacent side portions of each of said cooling wings from said first cooling wing to said last cooling wing, so as to provide a continuous passage for gases extending in series from said entrance chamber through all said cooling wings to said discharge chamber.

5. An exhaust silencer for internal combustion engines and the like, comprising walls forming an elongate entrance chamber of predetermined length and having at one end thereof an entrance opening for a stream of exhaust gases to be silenced, walls forming a discharge chamber disposed in substantially parallel relation to said entrance chamber, said entrance and discharge chambers being substantially coextensive in the direction of said predetermined length, and said discharge chamber having an exit opening for the flow of gases from said silencer at the end thereof opposite that end of the silencer at which gases are adapted to be supplied to said entrance chamber, a casing rigidly mounted with respect to all said walls and including a pair of spaced Walls and a center baille jointly forming a gas cooling wing disposed in substantially radial relation in respect to said discharge chamber and substantially coextensive therewith in the direction of said predetermined length, said center bafiiebeing mounted on a wall forming said discharge chamber, said spaced walls and said center bai'lie comprising walls bounding a through passage for gases through said wing, a perforated wall in said wing secured to and cooperating with a portion of the walls bounding the through passage thereof to define a pressure cushioning chamber in said wing which is completely closed to said through passage except for the perfora tions of said perforated wall, so as to leave in said wing a through passage for gases uninterrupted by said perforated wall, while providing for the flow of gases into and out of said pressure cushioning chamber through the perforations of said perforated wall, a passage formed between one of said pair of spaced walls and said center baflie and coextensive with said predetermined length from said entrance chamber to said cooling wing on one side of the center baffle thereof, and a passage formed by some of said walls and said casing and coextensive with said predetermined length and extending from that portion of said cooling wing on the other side of the center baflie thereof to said discharge chamher.

6. Any exhaust silencer for internal combustion engines and the like, comprising walls forming an elongate entrance chamber of predetermined length and having at one end thereof an entrance opening for a stream of exhaust gases to be silenced, walls forming a discharge chamber disposed in substantially parallel relation to said entrance chamber, said entrance and discharge chambers being substantially coextensive in the direction of said predetermined length, and said discharge chamber having an exit opening for the flow of gases from said silencer at the end thereof opposite that end of the silencer at which gases are adapted to be supplied to saidentrance chamber, a casing rigidly mounted with respect to all said walls and including a pair of spaced walls and a center baiile jointly forming a gas cooling wing disposed in. substantially radialrelation in respect to said discharge chamber and substantially coextensive therewith in the direction of said predetermined length, said center baffle being secured to one of said walls formin said discharge chamber, said spaced walls and said center bafile comprising walls bounding a through passage for gases through said wing, a V-shaped perforated Wall disposed with the apex of the V along and surrounding the edge of said center baiiie remote from said discharge chamber with the edge portions of said perforated wall parallel to the apex of the V secured to said walls providing said discharge chamber, a second V-shaped perforated wall similar to the firstnamed perforated wall but with a greater included dihedral angle at the apexof the Vand disposed and secured similarly to and outside said first-named perforated wall, said perforated walls and said center baffle providing, with parts of said walls providing said discharge chamber, two primary and two secondary pressure cushioning chambers in said wing, so as to leave in said wing a through passage for gases uninterrupted by said perforated walls, while providing for the flow of gases into and out of said pressure cushioning chambers solely through the perforations of said perforated walls, a passage formed between one of said pair of spaced walls and said center baffle and coextensive with said predetermined length from said entrance chamber to that portion of said cooling wing on one side of the center baiTre thereof, and a passage formed by some of said walls and said casing and coextensive with said predetermined length and extending from that portion of said cooling wing on the other side of the center baflle thereof to said discharge chamber.

'7. An exhaust silencer in accordance with claim 6, wherein the perforations .of said first named perforated wall occupy about 30% of the area thereof, and wherein the perforations of the second named perforated wall occupy about 50% of the area thereof.

8. An exhaust silencer in accordance with claim 1, comprising in addition, a receptacle for a liquid gas-treating reagent communicating above the surface of the liquid therein with one of said passages, and means tending to cause gases to flow past and in contact with liquid in said receptacle.

9. An exhaust silencer in accordance with claim 1, wherein a plurality of gas cooling wings, each as aforesaid, are provided between said entrance chamber and said discharge chamber, passages for gases connecting said wings in series, and comprising in addition, a receptacle. for a liquid gas-treating reagent communicating above the surface of the liquid therein with'one-of said passages, and means tending to cause gases to flow past and in contact with liquid in said receptacle, said receptacle being disposed below one of the last named passages connecting similar as cooling wings when said silencer is positioned with its dimension along said predetermined length substantially horizontal, said receptacle communicating with said one last named passage through a perforated wall, and wherein said means tending to cause gases to flow in contact with liquid in said receptacle comprises a deflecting bafile opposite said perforated wall tending to deflect gases through said perforated wall and into contact with the surface of liquid in said receptacle.

WILLIAM C. DIEHL, JR.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,049,433 Winslow Jan. 7, 1913 1,395,920 Libenschek Nov. 1, 1921 1,745,492 Kelch et a1 Feb. 4, 1930 1,772,589 Beamer Aug. 12, 1930 1,839,462 Bourne Jan. 5, 1932 2,101,389 Fischer Dec. 7, 1937 2,138,510 Rauen Nov. 29, 1938 2,367,473 Smith Jan. 16, 1945

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