US2943695A - Silencer - Google Patents

Description

July' 5, 1960 J. JEFFORDS 2,943,695

SILENCER Filed Oct. 25, 1957 3 Sheets-Sheet l INVENTOR (lose vb I (la ford;

ATTORNEY July 5, 1960 J. JEFFORDS 2,943,695

SILENCER Filed om. 2a, 1957 s Sheets-Sheet? ill-Ill I m1 INVENTOR dosc p/v C/e/fqrcfs ATTORNEY J. JEFFORDS July 5, 1960 SILENCER 3 Sheets-Sheet 3 Filed Oct. 23, 1957 -high compression gas United States Patent 2,943,695 SILENCER Joseph Jefliords, 700 Park Ave., Baltimore, Md.

Filed Oct. 23, 1951, Sen. No.'691,863

3 Claims. 01. 181-50) The present invention relates to silencers for fluid exhausts whether they are of either pulsating or continuous flow. The silencer is constructed primarily for portable pneumatic-driven apparatus, such as grinders, sanders, hammers, and the like. However, it may be employed in any type of exhaust where a silencer would be required or preferred whether portable or stationary.

One object of the invention is to provide a silencer that is compact and efficient and one that will reduce the to substantially atmospheric pressure.

Another object of the invention is to provide a disposable and sound absorbing element which may be easily and quickly changed.

A further object is to provide an adjustable and removable air diif-user for the silencer which will further diffuse the exhausted gases as they are passed from the silencer and which may be utilized to hold the sound absorbing and dissipating element in place'in the silencer.

A still further object of the invention is to provide means whereby the sound absorbing and dissipating element is surrounded by a resilient cushion for allowing slight movement thereof longitudinally and relative to the outside housing of the silencer.

While several objects and uses of the invention have been set forth, it is not intended that they be conclusive, as other objects and uses may become apparent to those skilled in the art as its nature is more fully disclosed.

The invention consists in its novel construction, combination and the arrangement of its several parts, all of which are illustrated in the accompanying drawings and described in the description to follow.

Figure 1 is a sectional view of the silencer.

Figure 2 is an elevational view of the replaceable sound absorbing unit carried by the silencer.

Figure 3 is a view of the silencer similar to that shown in Figure 1 partly in elevation, the outer portion being broken away in order to disclose the sound absorbing and dissipating unit.

Figure 4 is a separate detailed view somewhat in plan of the sound diffuser identified with the invention.

Figure 5 is a sectional view taken along the line 5-5 of Figure 3.

Figure 6 is a view in perspective showing the silencer in use with a pneumatic grinden.

Figure-7 is a top plan view of the same. A

In referring to the drawings like numerals are used to point out like and similar parts throughout the several views. 1

,Preferably,'the silencer has ajtapered or cone-shaped outer rigid hollow housing 10. This housing 10 is shown as being generally of cylindrical form in cross-section, but it may have any desirable'conventional cross-sectional shape, such as square, rectangular, etc. Also, the housing may increase its diameter in steps rather than being tapered, if desired.

The small end 10' of the housing. 10 is provided with an air intake opening 12 adapted to engage the exhaust end of the apparatus or for connecting it with an exhaust conduit. One means for accomplishing this is by a threaded coupling 12'. The larger end 10 of the housing 10 is provided with an opening 19 having a diameter at least twice the size of the air intake opening 12 on the opposite end of the housing just described. Surrounding the outer edge of the larger end 10" is a fixed ring 14. Over the larger end 10" of the housing 10 and the fixed ring 14 is a sound ditfuser D which is provided with an outer casing 20 having an inner side 20' adapted to be secured to the housing. The side is fun ther provided with a circumferential flanged portion 20 adapted to slidably fit over the ring 14. On the side 20 of the difiuser casing 20 there is an opening 22 at least as large as the opening 19 leading from the larger end 10" of the housing. In the portion 20" is a plurality of threaded holes 20" so spaced about its circumference as to threadably receive screws 18. Adapted to slidably engage the inner surface of the ring 14 is a second ring '16. The ring 16 is provided with a number of spaced apertures adapted to slidably receive screws 18 which are also opposite the threaded holes 20". By this arrangement the diffuser 20 may be adjusted about the axis of the housing and fixed in any desired position by tightening down on the screws 18, or the degree of tightness of the screws may be sufficient to enable the turning of the difiuser to any desired position and maintained in said position without additonal tightening of the screws. The diffuser is provided with an opening 23 which is at ninety degrees with the opening 22. The area of the opening 23 is at least as large as the opening 22.

Over the outer opening of the diifuser 20 is a perforated plate 24. The perforations are in the form of openings 25. The total area of the opening 25 is also at least as great as the area of the openings 19 and 22 in the larger end 10f of the housing 10.

In the operation of most apparatus by compressed air, there are always small amounts of oil, dirt and the like 7 being discharged, and the ordinary silencer soon becomes clogged with this oil, dirt, etc., which is prone to get on the operator, or the work, or both, and it is the purpose gularly disposed to each other, the angles of the portions 30 and 30' of the side walls being in separate planes substantially at right angles to each other and are joined along both their respective inner and outer edges. The :wall sections 30 are angled to face towards the inlet end of the silencer and are provided with a plurality of openings 32. The inner wall surface of the member A consists of a plurality of hills 34and valleys 36 sloping from the outer'perimeter angularly toward the inner apex centerwise. On the outside of the side walls and within the recesses oppositethe inner hills 34 there'is provided a relatively loosely packed mass of'g'lass fibers- 39, usually referred to as .fiber glass, or other suitable and available interstitial material,which extends out-' wardly to a line drawn between the lower points of'the inner valleys 36. About the glass fibers 39 there is a felt wrapping 38, or other suitable fibrous non-sound conducting material.

The elements A, 38 and 39 go to make up the sound absorbing and dissipating insert unit.

The sound-" absorbing element A may hesecured to each end of'the covering 38 for keeping. the element. in. full. extended position, the small end of the. element A being secured to the covering 38 at 42, and the larger end being secured to the cover38r at. 44;. This sound-absorbing and-dissipating'dispcs able element is'zadapted to be insertediwithinl the larger endlof the housing 10 and to fit snugly therein", andz is: held in.- place positionallyi by any conventional? means onlack oi displacement space. In.the pre'sent dis'- closure the sound-absorbing: unit: is shown held within the: housing by the gas-diffusing:memberztllwhich has herein before-been described: as adjustably securedto. the larger end of the silencer.

Within the diffuser D there isprovided an inner cover ing 21 of a; material: having a minimum amount: ofsound transmitting qualities;- suchas fiber glass, papier-mache', felt, or other interstitial material;

The bellows shaped sound-absorbing and dissipating ele'mentiA; with its: angledside portions 30" and 30 ex tends the full length of the silencer housing It The member A; is tapered outwardly in the same proportionsas thehousing 10 as" it approachesthe outlet endof the housing. The member A is-fo'rmed of a non-sound transmitting material and is preferably molded from papier-- mache, plastic, or similar interstitial material.

The air inlet 12 to the housing, as stated before, ispreferably of substantially at least one-half the diameter of the' outlet opening 19 in the housing. It willbe noted that thesound-absorbing' element A- is of a structure that has a plurality of connecting sound receptacles in which the 'Wallportions 30' and rneet each other at right angles. This type structure also lends itself to a slight oscillation lengthwise of its long axis of the housing-pant icularly when its opposite ends are held substantially at fixed points. The openings 32 in the wall portion 30' also act to allow the air pressure to be evenly distributed on the'inner and outer surfaces of the wall sections 30 and'30' to prevent collapse and distortion of the walls.

In using the silencerwith some types of tools; or apparatus, a handle 4% is provided to aid in'manipulating. and balancing the tool. However,.the housing may very well'be used. for ahandle itself.

The silencer is' 'illustrate'd in use with a grinding tool as shown in'Figures 7' and 8. These grinding tools comprise generally a rotatable arbor (not shown) carried within a casing 52' on which issecured a grindingwheel 56; Compressed air i'sled into the casing by the flexible conduit 58 and exhausted through an opening 60" which is connected with the threaded connector 12' of the silencer. The flexible conduit 58 is in turn secured to a rigid conduit 61'. Associated with this rigid portion 61 is an air valve control lever 62. This rigid conduit 61 serves as a guiding. and manipulating handle for the apparatus;

In operation, compressedair is fed into the casing. 52 which rotates the arbor and the grinding wheel 56 by the principle ofturbine propelled fins. (not shown). The air is exhausted out of the opening 6%) into'the small inlet 12 at the small end of the silencer. As the air moves through the silencer, it expandscontacting with. force the sides 30 of the. member A in particular, which. is angled toward thev oil-coming air. Fart of}? the air. and sound passes through the openings 32 into the fiber glass 39 and is cushionedthereby whichlalsobuilds up a pressure. onthe outside of the walllportions 30 and '30.'.. The sound con tacting thesurfacesfitl and 30. is'rebounded atsright angles to. eachother, and, therefore, the, sound. is. disrupted and. silenced. by the-principle of losing sound valusby chang.-. ingthesonnd wave direction'. The': member'A, beginning.

at its smaller end, gradually increases in cross-scctional area toward the: larger end of the housing and the outlet end of the silencer which, in turn, increases the size of the connected sound receptacles. This allows the compressed air to expand" progressively and to return quite 4 nearly to normal atmospheric extent. dissipate the. sound.

When the air and sound enter the air diffuser 20, the direction of the sound and air are again changed at an angle of approximately 90 degrees, which change in direction further dissipates the sound. The sound is still further reduced by passing the exhaust air from the difiuser outwardly throughthe plurality of openings 25 at the outer end of the ditfi'lser.

The silencer is not onlyazla titerl to use on such apparatus as shown insFigures 7 and 8,. but may be used in many other types oftbols' or apparatus such as previously referred to, and other instances too numerous to pressure, and to a large mention.

The location of the silencer on the apparatus is important. It is located at a point not more than degrees from the air intake and handle member in order to provide a second handle at a convenient location and to make the? apparatus the more maneuverableand available to work into close places? particularly in corners of. various structures. The position: of the diffuser is adjustable to directth'e exhaust. gases toward the work, or: the apparatus may: be moved-into such apositionover; the work asto. remove or. blow objectionable abrasives,=.grindings-, etc; from the work surface.

While the invention has been: illustrated and described in. a particular. form, it is not intendedas. a limitation and its scope is: best defined in the appended claims which have been allowed in view of the prior art.

l. A. silencer for absorbing. and dissipating: the sound of high pressure exhaust gases from fluidactuatcd apparatus comprising, means for attaching the silencer to he said apparatus, the silencer having an outer elongate rigid continuous-side wall and a. gas inlet opening at one enclfor receiving the high pressure gases and-a out let opening in the opposite end of the housing from which the gases are'exhausted from the silencer under low pressure to the atmosphere, the housing being. of smaller di ameter at the end. of the housing adjacent the gas inlet opening of larger diameter at the end adjacent: the gas outlet opening, the housing increasing progressively in. diameter: from 'the' end adjacent. the: inlet opening, to the end adjacent: the outlet opening. for gradually; increasing the cubic area: of the housing to provide space for the expanding gases as their. pressure: is lowered, an elongated separate insertable disposable. inner element of substantially the same length and: adjacent. the. inside surfaceofthe housing and form-fittingwith.respectatosaid housing surface, said insertableelement having an conitinuous bellows shapediside wall inwhichthalfi of the inner surfaces of the bellows. Wall areangled toward: the gas inlet and the other half are: angled toward the. gas outletprov-iding a plurality of communicating sound' receptacle therein, the diameter of the bellows insert in-- creasingin diameterfrom the gas intake end of the silencer to the gas outlet end thereof, a resilient cushion surrounding the bellows w-all element andrncans removably engageable with the exhaust end of the silencer housing for. retaining the same within the housing.

2. A silencer for absorbing and dissipating the. sound of. high pressure exhaust. gases from fiuidactuated apparatus comprising, means. for. attaching the silencer to the said, apparatus. the silencer having an. outereiongated rigid continuous?sidevwalliand a. gas inlet openingatone endtifor:recciving'thehigh pressure; gases. anda gas! out let opening in the opposite end of thehousing from'rwhich the gases are exhausted-from the silencer under low-pressure to the atmosphere; the housing being of smaller diatncter at the end of the'housing adjacent the gas inlet opening and of larger diameter at the and adjacent the gas outlet opening, the housing increasing progressively indi'ameter 'from the end adjacent the-inlet'opening to the end adjacent the outlet opening for gradually increasing the cubicarea of the housing'to provide space-for'the-en panding gases as their pressure is lowered, an inner element Within the housing having a central passage increasing in diameter in the same ratio as the outer housing extending therethrough, the walls of the inner element having a plurality of rigid angled surfaces positioned substantially at right angles to each other extending about the inner element and increasing in area progressively from the small to the large diameter of the element for engaging part of the gas stream passing through the central opening for changing the direction of that part of the gas stream and directing the same back into the remaining portion of the gas stream passing through the central opening, a low sound conducting wrapping extending about the inner element adapted to fit into the said outer housing, a gas diffuser fitted to the large exhaust end of the housing having an inlet at least equal in size to the gas outlet of the inner element and an outlet in the storm of a plurality of small openings of which their total areas are at least equal to the area of the diituser intake opening 3. In a device as claimed in claim 2 in which the sound absorbing element is provided with a plurality of openings on the surfaces of the bellows element angled toward the gas inlet opening for admitting air and sound waves beyond the bellows surfaces for equalizing the pressure on each side of the bellows surface to prevent its collapsing under the high pressure of the exhaust gases.

References Cited in the file of this patent UNITED STATES PATENTS 1,115,704 Manes Nov. 3, 1914 1,162,064 Hutton Nov. 30, 1915 1,442,196 Truelson Jan. 16, 1923 2,073,480 Jimerson Mar. 9, 1937 2,154,133 Mcllvaine Apr. 11, 1939 2,166,218 Morrison July 18, 1939 2,206,259 Nield et al. July 2, 1940 2,342,905 Smellie -1 Feb. 29, 1944 2,561,726 Cherain July 24, 1951 2,643,731 Schmid June 30, 1953 FOREIGN PATENTS 704,741 France Feb. 24, 1931 287,597 Italy July-28, 1931 563,110 Great Britain July 31, 1944 553,321 Italy Dec. 22, 1956

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