US2502017A - Suspension means for acoustical absorbers - Google Patents

Description

March 28, 1950 G; BEERS SUSPENSION MEANS FOR ACOUSTICAL ABSORBERS Filed Dec. 27, 1945 x Fly] ///////////////////////////1 V////////////// f lnnentor 'earye L Been* (Ittorneg Patented Mar. 28, 1950 UNITED STATES PATENT' OFFICE SUSPENSION MEANS FOR ACOUSTICAL ABSORBERS George L. Beers, Haddonfield, N. J., assignorto Radio Corporation of America, a corporation of Delaware ApplicaticnDccenher 27, 1943, Serial No. 515,'763

volume of air and the wall structure of which is constituted by a material which is perviousto sound waves 'but which offers a high dissip'ative 'impeclance thereto` By making the wallstructure of such a material and making thecavity or space within the casing so large that'the Volume of air therein offers a very small impedance to the sound waves, a very highly efcient clifir'action type absorber is provided. i

As disclosed by Olsen in his aforesaid application, the absorbing unit or "acoustic sink," as he has called it, may be made up from a suitably blanked sheet which can be folded to provide a box-like structure. However, units so constructed require a series of clcling, assembling and mounting Operations at the point of use which are time c'o nsuming and relatively costly. i To avoid 'these objectio-ns, it has been proposecl heretofore to form the absorber units or sinks of a pair of complemental parts which may be nested together compactly for storage, but which can be assembled when the unit is to be set up for use byplacing the two'halves together and securing them to each other by an adhesive, adhesive tape, stapling, or the like. The assembled units arethen ready for installation on `suitable supporting members throughout e, room, auditorium, or other enclosure requiring acoustic treatment.

While the latter arrangement overcomes,to a i large extent, the objections noted above, it still involves certain Operations, such as the individual assembly and subsequent mounting of the units, which require considerable handling of the parts, and the primary object of my present invention is to greatly simpliy the assembly and installation of acoustic absorbers or sinks of the type set forth above whereby to materially reduce the cost of the complete installation.

More particularly, it is an object of my present invention to provide an improved acoustic absorber unit and. an improved acoustic absorber system which may be formed therefrom in a facile manner and with a. minimum of Operations.

Another object of my present invention 'is to provide an improved method of assemblng and installing acoustic absorbers of the type set `forth whereby both the assembly and the installation or mounting of the units will be accomplished in a single operation.

Still another object ofmy present invention is to provide an improved acoustic absorber of the diffraction type which is neat in appearance and which may be rendered suitably deoorative.

A further object of my present invention isto provide an improved mounting arrangement'for acoustic abs'orbers of the type set `forth as aresult of which the individual units can be' rea'dily cleaned When necessary.

Still a further' object of my present invention is to provide an improved acoustic *absorber con,-`

which can be reaclily installed even by one un skilled in' the art, which is very' inexpensivein cost, and which 'is highly efcient in use.

As proposed heretofore, the absorber units cr sinks are fabrioated in twohollo-W parte of suitable shape, such as co nes, pyramids, hemispheres, or the like, the -two parts being substantially identical in shape so that they can be nested'together for compact packlng when'assembled for storage or shipment. In accordance with my present invention, I provide each part with 'a pe- .ripheral ange so that when these partsare butted together with the fianges in *engagement with each other, the parts form a casing which encloses 'a cavity. The flanges are formed a-tthe large, open-ended, base portions of' the casing -halves, and `I provide a small opening in'the :cena r ter at the opposite or vertex endof each casng` half so that it can be threaded onto ta supporting line, suchas a-wre, string, tape, 'or the like which can be stretched across a room.

To assemble'the unitsor sinks,'the correct number of complemental casing halves are threaded onto the wire or other suitable line constituting the supporting memben'the letter being anchored at one end at a suitable mounting point. After the appropriatenumber of sink halves or arts are'threaded 'onto the wire so that they can be pushed together to form the clesired'number of complete c'asings or enclosures, the other end of the wire or the like is fastened at &suitable point following application of suicient tension thereto to keep it from sagging. Starting at one end of the supporting line, a clamp is placed thereon at a desired location for the first sink. Onehalf of this sink is pushed against the clarnp and the second half, with is peripheral fiange acing the fiange of the first mentioned half, is moved along the supporting lin until the two fianges butt together, after which a second clamp is fastened to the line to hold the two halves together.

The sink or casing halves are constructed of a material which is pervious to sound waves, but which oers a high impedance thereto, as taught by Olson in his above identified application. One material which has been found especially suitable is a felted product made from woocl pulp fibers which are accreted by suction from a pulp solution in known manner. This material, like blotting paper and the like, is constituted by a plurality of intertwined fibers of various lengths arranged more or less compactly and indiscriminately in random directions to provide a plurality of irregular, random passages of very small cross-sectional dimensions. These fine passages acrd communication between the exterior of the sink casing and the space or cavity enclosed thereby, and they provide the requisite dissipative impedance to the acoustical energy received thereby. A material of this sort is usually sufficiently fiexible and yieldable to have enough give to take care of any expansion or contraction of the wire or other similar supporting line due to temperature and humiclity changes. Thus, adequate pressure will always be maintained between the two casing halves to avoid leaking of the air between the cavity enclosed by the casing and the external atmosphere. This method of assembling and mounting the acoustic sinks not only avoids separate assembly and mounting Operations, but entirely does away with the need for gluing the two casing halves of the sink together. Moreover, the sinks are mounted symmetrically with respect to the supporting line, and this results in a neat appearance. If, after a period of time, the sinks have collected dust on the upper surfaces thereof, they can be rotated easily on the wire to provide ready access to the dust so that the dust can be brushed off. If desired, the sinks can be made in various colors and used for decorative purposes.

The novcl features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description of several embodiments thereof, when read in connection with the accompanying drawing in which Figure 1 is a fragmentary, partly sectional view of an enclosure representing a room or the like in which one arrangement of acoustic sinks according to my present invention is shown,

Figure 2 is an enlarged, central, longitudinal section of one form of acoustic absorber or sink according to my present invention,

Figure 3 is a similar view of a slightly different form of absorber according to my present invention,

Figure 4 is an end elevation of the supporting line and one form of clamping member mounted thereon, and

Figure 5 is a View similar to Fig. 1, but showing a somewhat dierent mounting arrangement of 4 acoustic sinks in accordance with my present 1nvention.

Referring more particularly to the drawing. wherein similar reference characters indicate corresponding parts throughout, and especially to Figs. 2 and 3, there is shown an elongated, flexible, supporting line I, such as a wire, string, tape, or the like, on which is mounted an acoustic absorber 3 comprised of two casing halves 3a and 3b of substantially similar form and symmetrically arranged on the line l. These casin halves are hollow, geometric figures of suitable shape, and may be cylindrical, conical, pyramidal, hemispherical, or of any other suitable configuration. A suitable material for the casing halves may be made by accretion of pulp fibers on a suitably shaped forming screen in the manner disclosed, for example, in Pare Patent No. 2,488,555, granted November 22, 1949, to provide a layer of intertwined fibers having fine passages therebetween. In the form of the invention shown in Fig. 2, the absorber unit 3 is made up of two conical casing halves 3a and 3b, whereas in the form shown in Fig 3, the two parts aa and 3b are formed substantially as hemispheres. In any case, the casing halves 3a and 3b are open at their larger ends or base portions and are there formed with radially outwardly extcnding peripheral flanges 5a and 5b, respectively. At their opposlte or vertex ends, th casing halves sa and 3b are formed with small collars Ta and "lb, respectively, (exaggerated somewhat as to size in the drawing for the purpose of illustration), the collars 'la and 'lb being formed with small openings Sa and 9b of a size just sufiicient to freely receive the supporting line or wire I. Thus, the wire l may be threaded substantially axially through the casing parts 3a and 3b by merely passing the wire through the openings ea and sb and sliding the parts along the wire to any desired location.

In installing an assembly of acoustic absorbers or sinks according to my present invention, one end of the wire or line I may first be Secured to one wall of a room ll requiring acoustic treatment, as by means of a, suitable anchoring bolt I 3. The requisite number of casing halves Sa and 3b in complemental relation, that is, with the fianges Sa and 5b of each cooperating pair facing each other, are then threaded onto the wire l. Finally, the right-hand end of the wire I may be secured to a second bolt or the like I'I which is Secured to the opposite wall of the room ll, with suitable tension applied to the wire, as by a turnbuckle or the like (not shown) which may be hidden from view by an appropriate casing or cover of ornamental appearance.

At a suitable location, such as the point I in Fig. l, a suitable anchoring or locking device l5 is placed on the wire. The anchoring device !5 may be constituted by a substantially U-shaped, resilient member provided with oppositely directed slits |5a and I5b to form resilient barbs or the like |5c adapted to bite into the wire l, the space between the tabs l5c being somewhat smaller than the diameter of the wire i. Reading from left to right in Fig. 1, the lefthand anchoring member [5 is first applied to the wire i sonewhat to the left of its shown position and it is then moved slightly to the right along the wire I. This causes the barbs l5c thereof to protrude to the left, as clearly shown in Figs. 2 and 3, so that if an attempt is thereafter made to move the anchoring member |5 back to the left, the barbs or tabs l5c will bite manner.

into the 'wire and prevent such movement. The casing half sa is then moved to the left until its collar 'Iais brought into engagement With the left-hand anchoring member [5. Thereafter, the casing part db is moved over to the left until its fiange b abuts against the flange 5a of the casing part sa. The right-hand anchoring member !5 is then applied to the wire I somewhat to the right of its shown position and it is moved to the left until it engages the collar lb of the casing half 3b and suitable pressure is applied atthe fianges 5a and 5b. The absorber unit at iocation I is then complete. This procedure may be followed for each of the absorber units or sinks at locations II, III and IV which represent suitable, spaced mounting points along the wire l.

In the form of the invention shown in Fig. 5, the absorber units 3 are mounted on vertically extending lines i which. may be Suspended from the ceiling of the room H in any appropriate The lines i may be maintained under suitable tension by means of weights' IS which are secure'd `to the lower ends thereoi. Otherwise, the individual absorber units 3 and the manner of mounting the same may be similar to that described above in connection with the horizontal line arrangement of Fig. 1. In any case, it will be observed that the casing halves :ia and 3?) are assembled and mounted in a single operation and without the necessity of gluing or otherwise securing the same to each other.

When assembled in the complemental relation shown in the drawing, the casing parts Sa and se enclose a cavity 20 which is sufficiently large to have a large acoustic capacitance and thereio'e to provide only a very small acoustic impedance to the incident sound waves received bythe absorber units 3. The material of which the casing parts aa and 31) are made is pervious to the sound waves but offers a large, dissipative impedance thereto in accordance with the teachings of Olsen in his above identified copending application. Being rather loosely mounted on the supporting line i so as to be normally freely slidable thereon, it is apparent that the units 3 can be readily rotated on the line despite the fact that they are anchored against longitudinal movementthereon Thus, when dust has' accumulated on. the top surfaces thereof, they can be easily rotated through a sufiicient angle to permit ready access to the portions requiring cleaning. Also, it will undoubtedly be apparent that the unit's or sinks 3 can be made suitably decorative to enhance the appearance of the room in addition to providingthe desired acoustic efleote. All these and other advantages are affordecl by the present invention while still permitting the individual casing halves to be assembled in nested relation for storage and the like.

Although I have' shown and described several I arrangemcnts and types of acoustic absorbers according to my present invention, it will, no doubt, be apparent to those skilled in the art that many other variations are possible. .For example, the oasing halves 3a and 3b need not be made as geometric figures having surfaces of revolution, but may be in the form of pyramids, parallelepipeds, or the like', and if they are formed on surfaces of revolution, they may be ellipsoids, tori, or the like. Furthermore, where it is not found desirable to make the sinks 3 of yielding material, the looking members l5 may be provided with a yieldable spring element which will have the requisite give longitudinallyalong 'the' line l. Also, instead of the type' of clamping or anchoring member l shown in detail inFig. i, other `suitable forms of anchoring members may be employed, such as an ordinary slidable collar with a looking set screw. If the latter form of looking member is used, then it will obviously be necessary to firstthread one locking collar onto the line I followed by two complemental casing halves sa and 31), in turn followed by a second looking collar. Of course, the latter form of looking member may be C-shaped or U-shaped, in which case the assembly may be made as described above in connection with Fig. 1. Other variations will undoubtedly readily suggest themselves to those skilled in the art. 'I thereore desire that myinvention shall not be limited except insoiar as is made necessary by the prior art and by the spirit of the appended' claims.

I claim as my invention:

1. A diffraction type acoustic absorbing system comprising an elongated supporting member and a plurality of acoustic absorbing devices mounted on said member at spaced points therealong, said devices each comprising a pair of complemental, hollow parts formed of sound absorbing material and cooperatively arranged to enclose a cavity, and said member passing substantially axially through said parts.

2. A diffraction type acoustic absorbing system comprising an elongated supporting member and a plurality of 'acoustic absorbing devices mounted on said member at spaced points therealong, said devices each com prising a pair of complemental, hollow parts :formed of sound absorbng material and cooperatively arranged to enclose a cavity, the partsof each pair being substantially similar in configuration, and said member passing subi stantially axially through said parts.

3. A diffraction type acoustic absorbing system comprising an elongated supporting member adapted ,to be Suspended in space, a plurality of devices formed of sound absorbing material mounted on said 'member at spaced points therealong, said devices each comprising a hollow structure enclosing a cavity and being normally freely slidable on said member, and means anchoring said devices to said member at 'said points.

4. A diraction type acoustic absorbing system comprising an elongated supporting membena plurality of devices formed of sound absorbing material mounted on said member at spaced points therealong, said devices each comprising a pair of complemental, hollow parts cooperatively arranged to enclose a cavity and being normally freely slidable on said member, said member :passing substantially axially therethrough, and means anchoring said devices to said member at said points.

5. An acoustic absorbing system according to' claim 4 characterized in that said material is provided with a plurality of five passages therethrough whereby it is pervious to acoustical waves, said passages having such fine dimensions as to offer a large dissipative impedance to said Waves,

'7. An acoustical absorbing system according to claim 4 characterized in that each of said parts is constituted by a casing portion open at one end, characterized further in that said devices are each so arranged on said member that the open ends of the parts thereof are in abutting relation whereby to enclose a cavity, and characterized still further in that said anchoring means maintains each cooperative pair of said parts in cavity enclosing relation on said member.

8. An acoustical absorbing system according to claim 4 characterized in that each of said parts is constituted by a casing portion open at one end, characterized further in that said devices are each so arranged on said member that the open ends of the parts thereof are in abutting relation whereby to enclose a cavity, and characterized still further in that said anchoring means maintains each cooperative pair of said parts on said member in cavity enclosing relation and in pressing engagement with each other.

9. An acoustical absorbing system according to claim 4 characterized in that each of said parts is constituted by a casing portion open at one end and terminatin in a fiange, characterized further in that said devices are each so arranged on said member that said open ends of the parts thereof are in substantially aligned relation and the flanges of the parts thereof are in abutting reiation whereby to enclose a cavity, and characterized still further in that said anchoring means maintans each cooperative pair of said parts in cavity enclosing relation on said member.

10. An acoustical absorbing system according to claim characterized in that each of said parts is constituted by a casing portion having a large opening at one end and a small opening at the opposte end, said small openings being of a size just sufiicient to freely receive said supporting member, characteriaed further in that said de- Vices are each so arranged on said member that said first named ends of the parts thereof are in abutting relation whereby said large openings are in aligned relation and said parts enclose a cavity, characterized further in that said member passes through said small openings and said. cavity, and characterized still further in that said anchoring means maintains each cooperative pair of said parte in cavity enclosing relation.

11. An acoustical absorbing system according to claim 4 characterized in that each of said parts is constituted by a tapered casing portion open at its large end and having a small opening at its smaller end of a size just sufficient to freely receive said supporting member, charaeterized i further in that said devices are so arranged on said member that the large ends of the parts thereof are in abutting relation whereby said parts enclose a cavity, characterized further in that said member passes through said small openings and said cavity, and characterized still further in that said anchoring means is secured to said member in abutting relation to said smaller ends and maintains each cooperative pair of said parts in cavity enclosing relation.

12. A diffraction type acoustic absorber comprisng a pair of complemental, hollow parts each having an open end and an opposed, closed end, said open end terminating in a. fiange and said closed end having a small opening therein for the receptcn of a supporting member, said parts being adapted to be assembled in a relation wherein said fianges will face and abut each other and said open ends Will be in substantial alignment with each other whereby said parts will provide a casing which encloses a cavity, said openings being then at opposed ends of said casing, and said parts being constituted by a material which is provided with a plurality of passages therethrough whereby it is pervious to acoustical Waves, said passages having such fine dimensions as to offer a relatively large dlssipative impedance to acoustical energy received thereby.

13. A difiraction type acoustic absorber according to claim 12 characterized in that said parts are each constituted by a. geometric body having a surface of revolution.

14. A diffraction type acoustic absorber according to claim 12 characterized in that said parts are each consttuted by a. tapered, geometric body having a base end and an apex end, characterized further in that said fiange extends outwardly from said body at said base end, and characterized still further in that said small opening is provided at said apex end.

GEORGE L. BEERS.

REFERENCES CITED The following references are of record in the fle of this patent:

UNITED STATES PATENTS Number Name Date 271,'749 Stewart Feb. 6, 1883 1,483,365 Mazer Feb. 12, 1924 1308354 King June 2, 1931 1,816,618 Sklar July 28, 1931 2,1G0,638 Bedell et al. May 30, 1939 2,238,167 Genest Apr. 15, 1941 FOREIGN PATENTS Number Country Date 102914 Australia Jan. 6, 1938 certificate of correction Patent No. 2,502,017 March 28, 1950 GEORGE L. BEERS It is hereby Certified that errors appear in the printed specificaton of the above numbered patent requirng correction as follows:

Column 3, line 6, for the Words "with is read 'with its; column 6, line 64, for "five" read fine;

and that the said Letters Petent should be read With these corrections therein that the same may conform to the record of the case in the Patent Ofice.

Signed and sealed this 25th day of July, A. D. 1950 [SEAL] THOMAS F. MURPHY,

Assistant C'omm'ssioner of Patents.

certificate of correction r Patent No. 2,502,017 March 28, 1950 GEORGE L. BEERS It is hereby Certified that errors appear in the prnted specifioaton of the above numbered patent requiring correction as follows:

Column 3, line 6, for the words With is read with its; column 6, line 64, for "five" read fine;

and that the said Letters Patent should be read with these corrections theren that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1950 [SEAL] THOMAS F. MURPHY,

Assistant 'ommssioner of Patents.

certificate of Correction I Patent No. 2,502,017 March 28, 1950 GEORGE L. BEERS It is hereby certified that errors appear in the printed speeificaton of the above numbered patent requirng correction as follows:

Column 3, line 6, for the Words "With is read with its; column 6, line 64, for "five read fine;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Ofice.

Signed and sealed this 25th day of July, A. D. 1950 THOMAS F. MURPHY,

Assistant 'omm'ssioner of Patents.

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