US2205899A - Silencing device for pulsating gases - Google Patents

Description

. J1me 1940- A. s. CHIPLEY ,899

SILENCING DEVICE FOR PULSATINQ GASES Filed May 1, 1939 J/f LAX x M M Patented June 25, 1940 UNITED STATES PATENT OFFICE SILENCING DEVICE FOR PULBATING GASES Application May 1, 1939, Serial No. 271,031

14 Claim.

This invention relates to devices used for the prevention of noise caused by flowing, pulsating gases, such as the exhaust gases of internal combustion engines, or, as the terms are loosely used,

to muiiiers and silencers for such pulsating gas systems.

Although the invention is useful for the prevention of noise caused by pulsating gases generally, including, for example, the intake and delivery of air compressors, the most severe conditions are met in the prevention of noise caused by the exhaust of internal combustion engines and for-this reason the invention will be illustrated and described as applied to this particular problem.

A considerable variety of silencer constructions have been used and are now in use in coping with the problem of preventing or reducing to a minimum the noise attendant upon the operation of internal combustion engines. These various forms of apparatus operate on divers principles and are grounded on as many different conceptions of the causes of noise. A particular silencer may, for example, be of the baffle, resonator, three-pass, two-pass, expansion chamber or pack type, in simple or compound form, or it may embody a combination of two or more of these well-known types of apparatus.

The object of combining the different forms of apparatus is to take advantage of the characteristics peculiar to each and thus obtain a device having the desired mufiiing characteristics. The resultant product of such a combination contains a plurality of classifiable muiiling sections.

This expression will be used herein to denote a unit of one of the well-known forms of mufiling apparatus, such as those enumerated above.

A new type of noise-preventing device, known as the snubber, has recently been developed and commercially used. This device comprises a snubber tube into which the exhaust gases are projected at high velocity from the exhaust ports of the engine, an unconstricted shunt or by-pass passageway being provided around the snubber tube from the inlet to the outlet of the device. The snubber may be used as the silencer itself or a snubber section may be employed in com blnation with other types of mufliing sections in the building up of a composite device, designed to accomplish a specified function with the desired degree of perfection. The snubber operates on a gas-inertia principle and, although it differs in operation from most of the other types of mufflers and silencers in that it operates to modify the gas slug pressure-velocity peaks and thus remove the primary cause of noise 'rather than to merely suppress the noise after it has been generated or minimize secondary reverberation in the exhaust system, it may be loosely referred to as a muiiler or silencer.

The snubber tube of a snubber type of silencer is generally in the form of a perforated sheet metal member. It has been found that under certain circumstances, for example, when'the device is used with a Diesel engine, especially one of the low speed, low pressure type, solid materials carried by the exhaust gases stick to the inside surface of the snubber tube and cause an accumulation of tarry deposits. This material may in time plug the perforations and deprive the silencer of its ability to effectively snub the exhaust slugs. Accordingly, one object of the present invention is to obviate the possibility of plugging of the snubber tube of a snubber typeof silencer, or a snubber section thereof. A 20 further object is to simplify this type of apparatus and to thereby reduce the cost of the device without at the same time sacrificing its high silencing eiiiciency or depriving it of other desirable characteristics.

In the accompanying drawing: Fig. 1 is a longitudinal, sectional view of a simple embodiment of the invention;

Fig. 2 is a fragmentary view, similar to that of Fig. 1, illustrating a permissible modification; 30

Fig. 3 is a transverse, sectional view taken at the line 3-3 of Fig. 1,;

Figs. 4 and 5 are longitudinal, sectional views of compounded forms of the invention;

Fig. 6 is a longitudinal, sectional view illus- 35 trating certain modifications of the invention and the combination of the invention with another type of muilling section;

Fig. 7 is a longitudinal, sectional view (taken at the line 'I'| of Fig. 8) of another combination device including a modified form of snubber section; and

Fig. 8 is a transverse, sectional view taken at the line 8-8 of Fig. 7.

Referring specifically to Fig. 1 which illustrates 45 a simple embodiment of the invention, the unit is enclosed within a shell including a side wall I of circular or elliptical cross section and end headers 2 and 3. End header 2, which may be referred to as the inlet-end header, is provided 50 with an inlet opening 4 through which the gases enter the shell as indicated by the arrow. An inlet snout 5 may be attached to the inlet-end header at the inlet opening for convenience in mounting the device in the exhaust system of 55 the engine. An outlet openingt is provided in outlet-end header 3 and an outlet snout l, illustrated as integral with conduit 53, may be mounted in header 3. A partition 8 is arranged within the shell in spaced relation to inlet-end header 2 and divides the volume of the device into a by-pass chamber 9 and a snubber chamber In. An opening H is provided in partition 8 in alignment with inlet opening 4 and snout 5. This opening is preferably about as large as the area of inlet opening 4. It is preferable, although not essential, to develop the sheet metal of partition 8 at the periphery of opening ill to form a lip l2 for the purposes hereinafter more fully stated. This lip may be developed away from inlet opening 4, as illustrated at E2 in Fig. i, or it may be carried toward the inlet opening as illustrated at We in Fig. 2. A conduit 53 connecting bypass chamber 9 with the outlet of the device completes the structure of the unit of Fig. 1. The walls of conduit Iii are apertured in any suitable manner, as by perforating or slotting, to provide communication between snubber chamber it and the interior of the conduit. In the simple form of the device, as that shown in Fig. 1, it is desirable to limit direct communication between the conduit and snubber chamber it to the portion of the conduit remote from the outlet end of the device by perforating only that portion, as shown.

In the operation of the device, the exhaust gas slugs which are emitted from the exhaust ports of the engine at high velocity and under high pressure are conducted into the shell and toward opening it via the exhaust pipe (not shown) and inlet snout 5. The portion of each slug having sufficient inertia to do so, enters snubber chamber in through opening it while the remainder of the gases of the slug, the tailings traveling at lower velocities, follow the path of least resistance and by-pass directly to conduit l3 and thence to the atmosphere via outlet opening 6, outlet snout l and the tail pipe of the exhaust system. It will be seen that the path followed by the tailings is through an unconstricted passageway, that is, one whose transverse area at any point is not less than the area of the inlet snout and opening 4. This feature assures low back pressure operation of the silencer. The rapidly traveling gases entering chamber l0 through opening H are snubbed by reason of the limited means of escape from this chamber provided by the openings in the walls of conduit l3. The gases in chamber |0 cushion the impact of the entering gases, being compressed and absorbing the kinetic energy thereof. The gases then expand in chamber l0 and the pressure dissipates as the gases pass from the chamber into conduit 3 through the openings in the walls of the conduit. These gases follow the tailings to the atmosphere.

Although a device provided with a simple sharp-edged opening without the lip l2 will operate to substantially modify the pressurevelocity peaks of the exhaust gases, and thus prevent the noise-causing impact of the slugs with the atmosphere, it has been found that some edge noise is generated by the high-velocity movement of gases past the sharp edge of partition 8 as they pass through the opening. This undesirable noise is eliminated by means of a lip or flange, such as is shown at |2 or lza, this lip operating to ease the gases into chamber ID without necessitating their passage at right angles to the sharp edge of the partition. The lip may inlet opening it and snout l8 and outlet opening l9 and snout 20, respectively. Outlet snout is illustrated as integral with conduit 33 although it may, of course, be separate. The volume of the shell is divided into primary section 2| and secondary section 22 by intermediate par-- tition 23. Primary mufiling section 2| is divided into primary by-pass chamber 24 and primary snubber chamber 25 by partition 26 and secondary mufliing section 22 is divided into secondary bypass chamber 27 and secondary snubber chamber 28 by partition 29. Partition 26 is provided with 4 an opening 30 in alignment with inlet opening ill and an apertured conduit 3| passes through chamber 25 and connects the by-pass chambers 24 and 27!. An opening 32 is provided in partition 29 in alignment with conduit 3| and an apertured conduit 33 passes through secondary snubber chamber 28 and connects secondary bypass chamber Zll with outlet opening Hi.

The operation of the individual sections of this silencer is the same as that described in connection with the device of Fig. 1. The exhaust slugs are operated upon successively and the pressure-velocity peaks modified by the action of each. In addition to the individual operation of the two sections, it appears that an interference phenomenon between them contributes to the efiectiveness of the compounded unit in preventing noise. This may be due to the irregularity of the impacts of the successive slugs as they project into the successive chambers and as the modified slugs strike the atmosphere, or it may be due, at least in part, to interference of the' sound Waves within the device.

A modified form of the silencer of Fig. 4 is' shown in Fig. 5. In this device the inlet opening 34 and snout 35 are placed at the center of inletend header 36 of shell 31 and outlet opening 38 and snout 39 are placed in the center of outletend header 40. Primary snubber chamber 4| formed by partitions 42 and 43 receives the nuclear portion of each gas slug entering the device at inlet opening 34, the tailings of eachslug shunting through primary by-pass chamber 44 to the several apertured conduits passing through chamber 4|, such as conduits 45 and 46, two or more of which may be provided. The tailings are thus divided into a plurality of streams which pass on to the second section of the silencer. The.

expanded gases from chamber 4| also pass into the next section of the silencer at a plurality of points. An opening is provided in partition 41 in alignment with each of the conduits 45, 46' as shown at 48 and 49. Gases entering. the second section of the silencer may project into secondary snubber chamber 50 or pass through secondary by-pass chamber 5| directly into apertured con-, duit 52. In either case the gases then proceed to the atmosphere via outlet opening 38.

The silencer of Fig. 6 embodies modifications of certain of the elements of the apparatus above described and illustrates the combination of a snubbing section with a compound section composed of two treatment chambers each of which is known to the art as a "two-pass section, that is, a chamber having non-aligned inlet and outlet apertured tubes extending into the chamber from opposite points. This combined unit, as illustrated, is provided with two inlets 6! and 64 for connection, for example, to the two banks of cylinders of an engine of the "twin type. These inlets open into by-pass chamber 55. Openings 66 and 5! in partition 58 are in alignment with openings 53 and 54, respectively, and permit the passage of the incoming gases into snubber chamber 59. The lips or flanges 60 and 6| at openings 56 and 61 are substantially equivalent to the curved lips described in connection with the embodiments of Figs. 1 to 5, differing only in that they meet partition 58 at right angles rather than with a curve. A conduit 62 having a slot 63 connects by-pass chamber 55 with the expansion chamber 64 of the next succeeding mufiling section. The slot 63 is substantially equivalent to perforations and permits gases to pass from chamber 59 into the conduit. Perforated tubes 65 and 66 conduct the gases from chamber 64 into chamber 61 which latter forms the third mufiling section of the combination unit, being separated from the second muiliing section by partition 68. An outlet conduit 69 which is provided with a slot 10 carries the gases from chamber 61 through outlet opening H and outlet snout 12 to the atmosphere.

In the operation of the silencer of Fig. 6, the sharp pressure-velocity peaks of the gas slugs are modified by the snubbing action of the first muffling section of the silencer and the pulsations are further smoothed as the gases pass through the second and third sections of the unit in succession. The gases are then exhausted to the atmosphere in a relatively steadily flowing stream.

The combination unit of Fig. l is specially designed to remove high-frequency noises and to reduce so-ca'lled shell noise to a minimum. It also illustrates a snubber section which is essentially the same as those above described but in slightly different form. In this embodiment the snubbing section follows a pack section comprising sound-absorbing material", such as steel wool, glass silk, exfoliated vermiculite, etc., filled into the space between partition 1|, inlet-end flange I5, perforated tube 16 forming substantially an extension of inlet snout I1 and shell 18 of the silencer. The gases, after passing through the pack section, enter the snubber section. The gas stream entering the snubber section from tube 16 is spread by baffle 79 and directed radially from the axis of the silencer. The gases then pass through openings 80 which provide an annular entrance into the by-pass zone 8| of this section of the silencer. Battle 19 is mounted to the shell 18 of the unit, as shown at points 82. A partition 63 having peripheral openings in alignment with openings 80 in baflic I9 separates snubber chamber 84 from by-pass zone 8|. Slotted conduit 85 connects the by-pass zone with outlet fitting 86.

It will be apparent that the snubber section of the device of Figs. 7 and 8 operates as above described in connection with the previously described forms of snubbing section. The highvelocity portions of each gaseous slug projects into chamber 84 through the openings in partition 63 which are in alignment with openings 80 in baffle 19. The tailings may by-pass through zone 6| directly to conduit 85 and thence to the 1; atmosphere. Gases entering chamber 84 pass into conduit 86 through the slot therei and then also pass to the atmosphere.

Silencers oi the snubber type, such as the device of this invention, have the important ad.- vantage over units of the resonator type that they may be placed at any point in the exhaust line with substantially the same effectiveness. Since the primary cause of noise is obviated by means of the snubbing unit, the troublesome period noises do not occur. Also, back pressures are negligible since an unconstricted passageway is provided through each snubber or snubber section. The improved snubber construction described herein is exceedingly simple in construction and therefore inexpensive to manufacture. The various forms of the individual elements of the silencers described herein may be used in any of the arrangements disclosed and in other equivalent units of the type exemplified herein.

I claim:

1. In a device of the character described including a shell having an inlet opening and an outlet opening, conduit means adapted to conduct gases into said shell at said inlet opening, means forming a snubber chamber within said shell, said means including a partition arranged in spaced relation to said shell at said inlet opening to form a by-pass chamber and having an opening therein in alignment with said conduit means, and at least one conduit passing through said snubber chamber establishing communication between said by-pass chamber and said outlet openmg, said conduit having an apertured wall and opening into said by-pass chamber at a point in non-alignment with said conduit means, the construction and arrangement of said device being such that gases entering said snubber chamber are free to expand substantially unimpeded therein and thereafter pass therefrom through the aperture or apertures in said conduit.

2. A device in accordance with claim 1 in which Ellie afizrtired wall of the conduit passing through c c m er comprises a wall h perforations therein. avmg dlstnbuted 3. A device in accordance with claim 1 in which the apertured wall of the conduit passing through the chamber comprises a wall having an elongated slot therein.

4. A device in accordance with claim 1 in which the-opening in said partition is provided with a hp at its periphery.

5. In a device of the character described including a shell having an inlet opening and an outlet opening, conduit means adapted to conduct gases into said shell at said inlet opening, means forming a snubber chamber within said shell, said means including a partition arranged n spaced relation to said shell at said inlet openmg to form a by-pass chamber and having an opening therein in alignment with said conduit means, and a conduit passing through said snubber chamber establishing communication between said by-pass chamber and said outlet opening, the portion of said conduit remote from said outlet opening being apertured, said conduit opening into said by-pass chamber at a point in nonalignment with said conduit means, the construction and arrangement of said, device being such that gases entering said snubber chamber are free to expand substantially unimpeded therein,

and thereafter pass therefrom through the aperture or apertures in said conduit.

6.-In a device of the character described including a shell having a plurality of inlet openings and an outlet opening, conduit means adapted to conduct the gases into said shell at each oi said inlet openings, means forming a snubber chamber within said shell, said means including a partition arranged in spaced relation to said shell at said inlet openings to form a by-pass chamber and having an opening therein in alignment with said conduit means associated with each of said inlet openings, at least one conduit passing through said snubber chamber establishing communication between said by-pass chamber and said outlet opening, said conduit having an apertured wall and opening into said by-pass chamber at a point in non-alignment with said conduit means, the construction and arrangement of said device being such that gases entering said snubber chamber are free to expand substantially unimpeded therein and thereafter pass therefrom through the apertured wall of said conduit.

7. A device of the character described comprising a cylindrical shell, an in1et-end and an outlet-end header enclosing the space within said shell, said inlet-end header having an inlet opening and the outlet-end header having an outlet opening therein, an inlet snout associated with said inlet opening and adapted to conduct gases into said shell, a transverse partition within said shell spaced from said inlet-end header to form a by-pass chamber into which said inlet snout opens, said partition having an opening therein in alignment with said inlet snout, and an apertured tube passing through the space within said shell between said partition and said outlet-end header and connecting said by-pass chamber with said outlet opening, said conduit opening into said by-pass chamber at a point in non-alignment with said inlet snout.

8. A device in accordance with claim 7 in which said opening in said partition is provided with a lip at its periphery.

9. In a device of the character described including a shell having an inlet opening and an outlet opening, conduit means adapted to conduct gases into said shell at said inlet opening, means forming a primary snubber chamber within said shell, said means including a partition arranged in spaced relation to said shell at said inlet opening to form a primary.bypass chamber and having an opening therein in alignment with said conduit means, a tube passing through said primary snubber chamber and connecting with said by-pass chamber at a point in non-alignment with said conduit means, said tube having an apertured wall, means forming a secondary snubber chamber within said shell, said means including a partition spaced from a wall of said primary snubber chamber to form a secondary,

by-pass chamber and having an opening therein in alignment with said apertured tube, and a .second tube passing through said secondary ed to conduct gases into said shell at said inlet opening, a partition intermediate the ends of said shell dividing the volume thereof into a primary and a secondary section the former being adjacent said inlet opening and the latter being adjacent said outlet opening, a transverse partition within said primary section spaced from the end closure to form a primary by-pass chamber into which said inlet opening opens and having an opening therein in alignment with said conduit means, at least one apertured conduit within said primary section connecting said primary by-pass chamber at a point in non-alignment with said conduit means with said secondary section, a transverse partition within said secondary section spaced from said intermediate partition to form a secondary by-pass chamber into which said apertured conduit opens and having an opening therein in alignment with said apertured conduit, and a second apertured conduit within said secondary section connecting said secondary by-pass chamber at a point in non-alignment with said first-mentioned apertured conduit with said outlet opening.

12. A device in accordance with claim 11 in which said openings in said partitions within said sections are provided with lips at their peripheries.

13. In a device of the character described including an elongated shell having an inlet opening at one end and an outlet opening at the other end thereof, conduit means adapted to conduct gases into said shell at said inlet opening, a plurality of connected mufiling sections arranged in series within said shell, the first mufiling section being connected with said inlet opening and the last mufiiing section in the series being connected with said outlet opening, one of said sections comprising means forming a chamber, said means including a wall having an opening therein, means for conducting gases toward said opening in said chamber wall, and an apertured conduit passing through said chamber connecting the spaces on either side thereof, the upstream end of said apertured conduit opening at a point in said wall other than at said above-mentioned opening therein, the arrangement being such that said gases are free to flow into said chamber and thence into'said conduit through the apertures therein or directly into said conduit at one end thereof.

14'. In a device of the character described including ashell and means for conducting gases thereinto and means for conducting gases therefrom, a snubbing section arranged within said shell, said snubbing section consisting of: a wall forming a by-pass chamber on one side and a snubber chamber on the other side thereof within said section, said wall having an opening therein, inlet means for conducting gases into said section, said inlet means opening directly into said by-pass chamber and being in alignment with said opening in said wall so as to conduct the gases toward said opening, and at least one conduit having apertured walls passing through said snubber chamber and opening into said bypass chamber for direct communication with said inlet means at a point other than at said opening in said wall, the construction and arrangement being such that gases conducted into said section pass forwardly therethrough and from said section through said conduit without reversal.

A ALFRED S. CHIPLEY.

Images