US 3322879 A
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Description (OCR text may contain errors)
May 30 1967 E. A. LINDGREN 3,322,879
SOUNDPROOF SCREEN ROOM Filed Jan. l2, 1955 3 Sheets-Sheet l 5o ez 22- '0 'FIG 4.
INVENTORS ERIK A. LINDGREN May 30, 1967 E. A. UNDGREN 3,322,879
SOUNDPROOF S CREEN ROOM Filed Jan. l2, 1965 3 Sheets-Sheet 2 WVENTORS. ERIKA. LINDGREN ATTY May 30, 1967 E. A. UNDGREN 3,322,879
SOUNDPROOF SCREEN ROOM Filed Jan. l2, 1965 `5 Sheets-Sheet 5 ATT'Y.
United States .Patent C ABSTRACT OF THE DISCLOSURE A soundproof double isolated electrically shielded screen -room in which panel frames have cross members of a thickness substantially less than the border members with sound insulatio-n mounted therewithin so that metallic shielding material on opposite sides of the panel is supported yonly by the frame members and the insulation without contact with the cross members. Compressible sound insulation is also disposed between the edges of the panel frames whereby vibration can only be subsonic in the panel and is not transmitted from frame to frame.
This invention relates in general to, improvements in double isolated electrically shielded enclosures or screen rooms for protection ynot only against the penetration of high frequency wave eminations and magnetic fields but also against the transduction of physical vibrations including sound waves whether they originate inside or outside of the enclosure.
` Cross references This invention concerns itself more particularly with the construction andassembly of -prefabricated demountable panel wall units having two spaced electrically isolated layers of sheet metal shielding; the electrical continuity between adjacent wall panels of the ty-pe illustrated in my earlier patents, Numbers 2,765,362, 2,860,- 176 and 3,070,646, reference to which is hereby made for a fuller explanation of the portability and double isolated electrical shielding characteristics contemplated in this invention; and, further to the soundproong of the panels against the transduction of sound in either direction or from one panel to another. y
Background of invention As already noted in the above mentioned patents, shielding eciency is related to physical Contact conductivity and non-permeability of metal shielding elements and this includes contiguous points in and between all shielding elements and in the electrical isolation between spaced inner and outer shells of multiple shielding elements. Thesev characteristics lend themselves to the transmission of physical vibrations.
The amount of spacing between the multiple shells further enhances magnetic attenuation and can range up to four inches although two inches of spacing is 'preferred particularly for optimum results with portable prefabricated panel constructions utilizing ka thin sheet of solid shielding material secured'to each side of a ydielectric core. This entails an increased size and weight factor. y
Consequently, in providing a desirable spacing distance, it is also desirable to save weight and employ open frame work rather than a solid dielectric core and then construct the panels so that the shielding elements will not act as drum headsy in transmitting 'sound therethrough and the solid elements of the frame work will not conduct vibrations from one to another ofthe panels.
2 Summary dnd objects of `invention Not only is it desirable to deaden 'sound vibrations within the confines of the panel, but one of the objects o-f tion dampening joint between abutting panel edges while maintaining f continuous electrical conductivity at all points. t
A further object of the invention is to provide an irnproved soundproof prefabricated double isolation panel utilizing weighted thin sheets of, solid metallic material resiliently stressed in spaced isolated relationship upon a light frame member with substantial clearance between the frame and the weighted sheets in areas where there is likelihood of relative movement therebetween. Other objects and advantages including ease and lightness of construction and assembly will appear from the following description and drawings in which:
FIG. 1 is a perspective view illustrating an isolation room made up from a plurality of panels for the Walls and top thereof having a basic frame Prefabricated panel construction embodying the invention;
- lines 4-4 in FIG. 1 illustrating cross-sectionally the connection of anytwo corner panels at the corner joints; and,
FIG..5 is an exploded preassembly orientation of panel elements making up the floor construction of the isolation room. f
' Panel structure Referring now to FIGS. 1 and 2 the basic construction of the intermediate panels 10 and corner panels 10a from which the dou-ble isolation and soun-d proof screen room 12 is fabricated is illustrated in connection with a frame member 14 that is two inches thick, and two sheets 22 of galvanized steel shielding of No. 24 gauge.
The frame member 14 is made up of two side members 16, two end members 18, all two inches thick, and intermediate cross ,members 20 that are only one and a half inches thick secured at their ends to the side members midway their thickness to leave ay quarter inch'of spacing on each face side from the faces of the side memelements, or both. The end and side frames define a central open area 24 and the cross members divide this up into compartments 26.
The sheet metal shielding is marginally flanged at 28 '(FIG. 3) to a depthof one-half an inch to lit snugly over and around the corners 30 -of the frame and to be disposed and terminate in the plane of the joint 32 established between abutting panelsltl. A reversely doubled ange 34 (FIG. 4) is required at the corner joints 36 for this purpose as will be understood from further explanation.
As mentioned the sides 16 and ends 18 of the frame 14 define a central open area 124, disregarding for a moment the cross members 20. A mask (not shown) corresponding to the silhouette of the frame 14 is laid upon the inside faces of each shielding member 22 to define an opening corresponding to the open area 24. Thereafter goop, an asphalt base mixture with solids in it which congeals but never hardens, is sprayed onto the exposed open area to a depth of one-eighth of an inch upon each shielding element to provide a weighting layer 38 which greatly lowers the inherent modulus of sympathetic vibration of the shielding sheet.
The mask is then removed from one of the shielding members 22 and replaced with the frame 14 and bats 40 of polyurethane cut from resilient sheet foam one inch thick and to the sizes of the compartments 26 defined by the frame between the members 16 and 18 and cross members 20 are then dropped in pla-ce within the flanges 28, two bats 40 being stacked together for each compartment 26. This provides a total thickness in each compartment of two inches. The mask is then removed from the other shielding members 22 and it is then inverted and in turn .laid over the assembly and pressed into place to compress the bats slightly.
The internal panel construction is thus completed and referring to FIG. 3 it will be observed that there still remains 1/8 clearance at 42 between the cross members and the surface of the weighting layer 38 carried by the shielding. This clearance is maintained by channel members 44 sometimes referred to as hat sections extending substantially the length of the open area 24 of the frame with the flanges 46 of the channel members soldered or otherwise adhered to the external surfaces of the shielding sheets 22 both upon the inside and outside surfaces of the panel. The channel members not only maintain the -clearance and prevent oil-canning of the sheet of shielding, but also serve as fastening brackets by which the panels can be yfastened externally to a building wall or upon which fixtures can be secured to the channel members upon the panel inside of the room. This fastening can be accomplished without putting a j hole through the sheet 22 of shielding.
Referring again to FIG. 3 where the edge abutting relationship is shown between adjacent panels, it will be observed that the anges 28 being only 1/2" wide there remains between the edges of opposite anges on each frame a space 48 of yl" 4of exposed frame material. Within this area a body 50. of polyurethane foam 1" x 1" is mounted and compressed. The body may be a 1" x 1" strip adhered on only one of the mating frame members or two 1/2 x 1" strips one on each of the two abutting frame edges.
Also referring to FIG. 3 the edges `are drawn together by pairs of L-shaped channel members 52a and 52b on opposite sides of each joint. The leg -4 of one channel mem-ber 52a overlaps the joint 32 while the co-operating channel member 52b is spaced back from the joint. Bolts 56 interconnect the opposing upstanding flanges 58a and 58h of each pair of channels and as the bolts are tightened they draw the flanges together. In this operation the opposing flanges of the shielding are placed under compressing the polyurethane strip 50 therebetween until the ,opposing flanges of the shielding are placed under comlpressive contact as a terminal accomplishment. When this is attained it will be observed that the overhanging legs 54 bridge and contact both face edges of the respective shielding members 22 at the joint 32 and in bridging the edges of the joint the legs 54 they obstruct direct ingress of the magnetic waves in the plane thereof. Thus, continuous electrical conductivity between the flanges abutting shielding elements is established at all points and obstruction of direct entry of the magnetic waves to the joint is provided. The compressed polyurethane serves as a sound deadening medium between adjacent frames.
Corner joints In FIG. 4 the same principles are employed at a corner where the outer corner edge of one frame member 10a is relieved to a depth of one half of its thickness and to a width of two inches leaving a ange portion 60 to engage laterally against the edge 62 of the adjacent panel. The shielding 22a on the flange portion is brought around t-he free edge of the flange to provide the reversely extending flange portion 34 yof one-half of an inch width for the purposes already described. In this embodiment however, one of the cooperating clamping elements is a flat or strap member 6'4 fastened to the upper surface of the panel and overhanging the corner to cooperate with the L-sha-ped channel 52a which overlaps the joint. Here again and at all joints the polyurethane strip 50 is provided and compressed to deaden the transfer of vibration from one frame to another.
Floor construction On the floor panels, the channel members 52 are omitted since wooden treadways either solid or lattice are provided. Below the oor panels, however, wooden floor frames are provided approximately 3A thick for the lower shielding elements of the floor panels to rest on, and along the bottom surfaces thereof facing the #door are provided strips of Ipolyurethane 1/2 x 1 which are compressed by t-he weight of the room. Although polyurethane sponge compressed solid can transmit some vibration, it is to be observed that with the irregularities conventionally experienced in oor levels, there is much polyurethane which are'in portions not compressed solid and these portions operate to dampen vibration entering the system.
Utility of invention In understanding -the invention it will be appreciated that a free sheet of thin metal such as copper and steel used for shielding material will respond to vibrations throughout a wide range of frequencies. This is due to the very small linertia of the thin sheet metal in a transverse direction. The present invention greatly increases this inertia by the addition of the weight and sluggishness of a pliant coating sprayed thereon, for example, an asphalt base product having solids and fibers therein and further fortified 'with heavy silicon which congeals yet never hardens to a brittle status. As coated with this composition vibrations above that of the lowest audible sounds are rejected at the initial or exposed surface of the metal sheet.
To prevent low frequency vibrations that might set the sheet metal shielding in motion notwithstanding the effect of the goop, polyurethane foam of extra thickness is used between the shielding elements. In doing this it will be appreciated that otherwise mere contact with polyurethane would not prevent initiation of the excursion even though it might attenuate the ultimate excursion. The excursion would proceed until the foam begins to be compressed, but by placing the polyurethane foam under initial yand appreciable compression, the attenuation is instantly effective, provided, however, that the responsive area of the shielding is not in contact with a solid intermediate member such as the cross frame members. This is eliminated by the cross member 20 being of reduced thickness to provide a Ms clearance protected by compressed polyurethane foam. This is found to be adequate even under wave forms such as those induced by heavy internal combustion engine exhausts, air pressure release waves, explosions or other suddenly induced heavy air movements in industry.
With respect to the compressed polyurethane at the joints and floor surface, these strips dampen squeaks that might be induced by walking around in the room or by vibrations in the floors of industrial plants with heavy loads transported over them, thereby isolating the room space from the outside space, and Vice versa, regarding the transmission of sound or heavy vibrations other than sheer Ibodily movement of the screen room as a unit.
Having thus described the invention and the preferred embodiment thereof it will be observed how the objects are accomplished and how various changes and substitution of equivalent materials can be made for the purposes set forth without departing from the spirit of the invention the scope of which is commensurate with the appended claims.
What is claimed is:
1. In a shielded enclosure a rectangular panel comprising a frame of predetermined thickness dening a central open space having cross members of a thickness appreciably less than said predetermined thickness traversing and dividing said central open space into compartments, a sheet of metallic shielding material covering each side of the frame and having marginal iianges turned over the corner edges of the frame and extending inwardly from the respective panel faces to cover minor portions of the edge faces of the frame and provide a space between terminal edges of the sheets that are on opposite sides of the frame to electrically isolate the sheets from each other, a coating of weighting material adhered to said sheets within the contines of said central open space, and compressible elements filling in the compartments defined by said cross members, said compressible elements and said coatings combined having a normal thickness greater than said predetermined thickness, and a strip of compressible material in said space between said terminal edges of a normal thickness greater than the thickness of said sheet of shielding material.
`2. The combination called for in claim 1 in which said frame along one edge is relieved to one-half of its thickness for a depth equal to said thickness and the marginal ilange of said metallic shielding material is reversely doubled at said one edge to extend around its corner edge and back upon the relieved portion to cover a minor portion of the face thereof.
3. The panel deiined in claim 1 with channel member means secured to the exposed surfaces of sheets intermediate the sides of the panel.
4. In a shielded enclosure a rectangular panel comprising a frame of predetermined thickness defining a central openspace having a sheet of metallic shielding material covering each side of the frame and having marginal flanges turned over the corner edges of the frame and extending inwardly from the respective panel faces to cover minor portions of the edge faces of the frame and provide a space between terminal edges of the sheets that are on opposite sides of the frame to electrically isolate the sheets from each other, a coating of weighting material adhered to said sheets within the confines of said central open space, and compressible elements disposed in said central open space, said compressible elements and said coatings combined having a normal thickness greater than said predetermined thickness, a strip of compressible material in said space between said terminal edges of a normal thickness greater than the thickness of said sheet of shielding material, and channel member means secured to the exposed surfaces of sheets intermediate the sides of the panel.
5. In a shielded enclosure a rectangular panel comprising a frame of predetermined thickness defining a central open space having a sheet of metallic shielding material covering each side of the frame and having marginal flanges turned over the corner edges of the frame and extending inwardly from the respective panel faces to cover minor portions ofthe edge faces of the frame and provide a space between terminal edges of the sheets that are on opposite sides of the frame to electrically isolate the sheets from each other, a coating of weighting material adhered to said sheets within the contines of said central open space, and compressible elements disposed in said central open space, said compressible elements and said coatings combined having .a normal thickness greater than said predetermined thickness, a strip of compressible material in said space between said terminal edges of a normal thickness greater than the thickness of said sheet of shielding material, and L-shaped channel members along the side edges of the panel, one of said members overhanging its adjacent side edge, and another one of which is spaced from its adjacent side edge.
6. In a shielded enclosure a pair of rectangular panels each comprising a frame of predetermined thickness deining a central open space having cross members of a thickness appreciably less than said predetermined thickness traversing .and dividing said central open space into compartments, a sheet of metallic shielding material covering each side of the frame and having marginal iianges turned over the corner edges of the frame and extending inwardly from the respective panel faces to cover minor portions of the edge faces of the frame and provide a space between terminal edges of the sheets that are On opposite sides ofthe frame to electrically isolate the sheets from each other, a coating of weighting material adhered to said sheets within the contines of said central open space, and compressible elements filling in the compartments dened by said cross members, said compressible elements and said coatings combined having .a normal thickness greater than said predetermined thickness, said pair of panels being disposed in edge abutting relationship with their marginal flanges in contact with each other rin isolated pairs, ka strip 0f compressible material in said space between said terminal edges and between adjacent f edge surfaces of said pair of frames of a normal thickness greater than the thickness of said sheet of shielding material, elongated members carried by said panels on the faces thereof along the adjacent side edges including one electrically conductive member carried by one of the panels and overlapping the line of said contact to bridge the flange engagement between adjacent sheets on the respective panels and another of the members carried by the other panel spaced from said line of contact, and means for drawing the said members toward each other to compress said strip of compressible material and with said contacting flanges under pressure contact.
References Cited UNITED STATES PATENTS 2,860,176 11/1958 Lindgren 174--35 3,092,218 6/1963 Clay 174-35 X 3,246,072 4/ 1966 Lindgren 174-35 DARRELL L. CLAY, Primary Examiner.