Abstract:
To enable the ready transport and erection of radiant energy shielded enclosures at locations having various immovable obstructions, shielded joints of several different types each having shielded splices therein are provided for the connection in the enclosure of adjacent sheets occupying a common plane or two right angular planes. A compound joint at the intersection of three right angular planes occupied by sheets of the enclosure is also provided. The construction is applicable to future expansion of existing shielded enclosures without sacrifice of shielding performance at the interface of the addition with the existing portion.

Description:
BACKGROUND OF THE INVENTION 
     The general objective of this invention is to provide a radiant energy shielded enclosure of increased operational efficiency, greater versatility of construction, and greater practicality. 
     More particularly, the invention satisfies a need for a radiant energy shielded enclosure which can be constructed in a variety of configurations around existing immovable obstructions, such as columns, in buildings without sacrifice in shielding performance. 
     Another object is to provide a shielded enclosure which can be constructed as an addition or extension of an existing enclosure, without loss of shielding performance. 
     Still another object is to provide a shielded enclosure which can achieve a shielding rating of 100 decibels at 10 gigahertz. 
     Other features and advantages of the invention will be made apparent to those skilled in the art during the course of the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic perspective view, partly in section, of a shielded enclosure erected around immovable obstructions in accordance with the invention. 
     FIG. 2 is an enlarged fragmentary perspective view of a portion of the shielded enclosure in FIG. 1 erected around a rectangular cross section obstruction. 
     FIG. 3 is an enlarged fragmentary vertical section taken on lines 3--3 in FIGS. 1 and 2. 
     FIG. 4 is an enlarged fragmentary horizontal section taken on line 4--4 of FIG. 2. 
     FIG. 5 is an enlarged fragmentary vertical section taken on lines 5--5 in FIGS. 1 and 2. 
     FIG. 6 is an enlarged fragmentary elevational view taken on line 6--6 of FIG. 4. 
     FIG. 7 is a similar view taken on line 7--7 of FIG. 3. 
     FIG. 8 is a similar view taken on line 8--8 of FIG. 5. 
     FIG. 9 is an exploded perspective view of a corner structure and splice utilized in the enclosure as depicted in FIGS. 5 and 8. 
     FIG. 10 is an enlarged fragmentary horizontal section taken on line 10--10 of FIG. 2. 
     FIG. 11 is an enlarged fragmentary plan view of the area of the enclosure encircled at 11 in FIG. 2. 
     FIG. 12 is a vertical section taken through a splicing channel on line 12--12 of FIG. 9. 
     FIG. 13 is a fragmentary vertical section taken through a tensioning element and associated parts on line 13--13 of FIG. 9. 
     FIG. 14 is a side elevation, partly in section, of a splined anchor nut for tensioning elements. 
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings in detail wherein like numerals designate like parts, FIG. 1 shows an enclosure of the Lindsay type constructed generally in accordance with U.S. Pat. Nos. 2,263,510; 2,263,511; and 2,364,083. While this type of enclosure is very well suited to accommodate the shielding means of the present invention, nevertheless the invention is not limited to use in a Lindsay enclosure or structure. 
     In FIGS. 1 and 2 of the drawings, a shielded enclosure 20 according to the invention is erected around two immovable obstructions 21 and 22 such as spaced building columns. The essence of the invention, to be described, lies in the formation of the various shielded corner joints and splices which enable the erection of the enclosure in the illustrated manner, without sacrifice in shielding performance and without greatly increased cost of construction. 
     The arrangement shown in FIGS. 1 and 2 is merely illustrative of one of many possible embodiments of the invention namely where two vertical building columns 21 and 22 are encountered. Utilizing the same essential components, now to be described, a shielded enclosure can be erected around other commonly found obstructions, such as horizontal beams, offset wall portions produced by closets, and the like. As previously explained, the invention finds utility in the construction of a totally new shielded enclosure or in an addition to an existing shielded enclosure without loss of shielding efficiency. 
     As shown in the Lindsay patents, the shielded enclosure 20 is constructed from a plurality of separately formed contiguous rectangular thin metal sheets 23 of various sizes. These sheets are joined along their meeting edges with adjacent sheets of the enclosure including along the various right angular corners in the structure. The essence of the invention resides in forming these joints between sheets in such a way that the resulting enclosure is highly effective in shielding radiant energy, as explained in the introductory portion of the application. 
     FIG. 3 shows a typical shielding joint between a pair of the sheets 23 which occupy a common plane in the enclosure, either horizontal or vertical. This joint comprises main channel members 24 which extend across any wall portion of the enclosure in end-to-end relationship and project exteriorly of such wall defined by the coplanar sheets 23. The main channel members 24 include opposite side flanges 25 which lie on the exterior faces of the sheets 23 and form rounded corners 26 with the body of the main channel around which edge portions of the sheets 23 are tensioned. Such tensioning or stretching is produced by an opposing tensioning channel 27 coextensive lengthwise with the main channel members 24 and fitting into the same snugly substantially as shown in the Lindsay patents. The corresponding edge portions 28 of the sheets 23 are held tightly in the narrow spaces between the two interfitting channels 24 and 27. The tensioning channel 27 has its closed side flush with the two interior faces of the sheets 23 to form a smooth interior surface for the shielding enclosure. 
     The tensioning channel 27 is firmly anchored at longitudinally spaced intervals by means best shown in FIGS. 13 and 14. This means consists of splined nuts 29 secured within spaced openings 30 of the main channel member 24, not shown in FIG. 3. Cooperative screws 31 are received in openings formed in the closed side of tensioning channel 27 and threadedly engage the nuts 29 within the space between the two interfitting channels. 
     As shown in FIG. 7, a pair of the main channel members 24 utilized in the joint or connection of FIG. 3 are in end-to-end abutting relationship with the interior tensioning channel 27 bridging their abutting ends. A relatively short splicing channel 32, also shown in FIG. 3, is applied over the exterior of main channel members 24. As shown in FIG. 12, splicing channel 32 has spaced threaded studs 33 fixed thereto and these studs are engaged by nuts 34 within the space defined by the opposing channels 24 and 27. The nuts, as well as the threaded shanks of the studs 33, are concealed in the finished enclosure. The joint and splice thus formed is mechanically secure and efficient in shielding against radiant energy. 
     FIGS. 4 and 6 depict another necessary corner joint and splice for the enclosure depicted in FIGS. 1 and 2. This particular joint is formed by a required number of end-to-end abutting M-cross section members 35 bridged exteriorly by relatively short splicing members 36 of matching cross section. The bridging member or members 36 have spaced threaded studs 37 similar to the studs 33 secured thereto and receive nuts 38 interiorly of members 35. 
     An adjacent pair of perpendicular sheets 23 have corresponding edge portions 39 held and tensioned by a continuous tensioner 40 which extends longitudinally of the corner joint defining the interior thereof. The tensioner 40 has an interior arcuate wall 41 blending smoothly with the perpendicular sheets 23 and forming a rounded interior corner, and opposite side flanges 42 which engage between the adjacent parallel walls 43 of the M-cross section members 35. Again, a spliced joint for the enclosure at one or more corners thereof is formed in a mechanically secure manner with radiant energy shielding efficiency. 
     A further typical corner structure occurring at several places in the enclosure 20 is shown in FIGS. 5, 8 and 9. In these figures, a pair of perpendicular sheets 23 are shown. Also shown are two perpendicular main channels 44 having side flanges 45. As shown in FIG. 8, two or more channels 44 in end-to-end abutting relationship are utilized along the two sides of the dual joint and splice depicted. Adjacent perpendicular flanges 45 of the two main channels 44 are joined by a continuous longitudinal weld 46 which has no interruptions. 
     A single splicing sheet 47 includes a center right angular corner portion 48 which interfits with the two flanges 45 joined by the weld 46. Two identical edge portions 49 of the splicing sheet 47 are held between corresponding side walls of tensioning channels 50 and main channels 44. The tensioning channels 50 are continuous elements along the entire length of the dual joint and across its splice or splices necessitated by end-to-end abutment of the main channels 44. Single edge portions 51 of perpendicular sheets 23, FIG. 5, are held by the other side walls of tensioning channels 50 within the main channels 44. 
     As described previously in connection with the joint and splice shown in FIGS. 3 and 13, the tensioning channels 50 are secured at intervals along their lengths by the screws 31 engaging with the splined nuts 29 held in openings of the two main channels 44. Inasmuch as this arrangement is common to the forms of the invention shown in FIGS. 3 and 5, the reference numerals designating both of the tensioning channels 27 and 50 have been applied to the drawings in FIGS. 9 and 13 for clarification. 
     Comparatively short splicing channels 52, identical to the channels 32, are employed to form splices along the dual channel joint of FIGS. 5, 8 and 9 wherever the longitudinally welded main channels 44 meet in end-to-end abutment, as depicted in FIG. 8. The splicing channels 52 are equipped with the previously-described threaded studs 33 which pass through apertures 53 in main channels 44 and receive nuts 54 which bear against the undersides of the main channels 44, as best shown in FIG. 5. At the region of each splice thus formed, the splicing sheet which is common to the dual splice effectively shields the enclosure against the entry of radiant energy. The provision of the continuous weld 46 joining the two main channels 44 in right angular relationship eliminates the need for corner panels and corner caps used in the prior art. These prior art elements are troublesome in that they tend to lose tension over a period of time, resulting in reduced contact and reduced shielding performance compared to the weld 46. 
     It should be understood in the several forms of joints already described, namely the joints of FIGS. 3, 4 and 5, that the main channels or members 24, 35 and 44 of the enclosure are sectional members which abut end-to-end, thus requiring the described splices. However, the tensioning elements 27, 40, 50 are continuous in the sense that they bridge a number of the splices at the meeting points of the sectional main channels or members. Therefore, a cross sectional view taken through a joint of the enclosure, such as FIG. 10, in a plane on either side of a splice, will not include the splicing channels 52 and the cooperating splicing and shielding sheet 47. 
     FIG. 11 depicts a further joint in the nature of a compound corner joint, necessitated along with the previously-described joints in the erection of shielded enclosures around various obstacles, as previously-discussed. In FIG. 11, an adjacent pair of the sheets 23 in a common plane are shown joined in enclosure shielding relationship by one of the simple joints illustrated in FIG. 3 at a region where there is no splice. Two additional sheets 23 at right angles to each other and also perpendicular to the common plane occupied by the other two sheets 23 in FIG. 11 are joined by one of the M-cross section members 35 described in FIG. 4 and a coacting continuous tensioner 40, also shown in FIG. 4. 
     Extending beyond the location of these elements 35 and 40 in FIG. 11 in right angular relationship around a corner of the obstruction 21 are two of the dual right angular joints of the types shown in FIGS. 5 and 10, in regions where there are no splices, and therefore no splicing channels 52 or sheets 47. The two connected pairs of main channels 44 as described in FIG. 5 are shown in FIG. 11, meeting at the right angular corner defined by the elements 35 and 40. Corresponding ends 55 of two of the channels 44 are butt welded to adjacent surfaces of the M-cross section member 35. A closure plate or gusset 56 overlies the end of the joint made up by the elements 35 and 40 and is welded into place around its margins, as shown. It may also be noted in FIG. 11 that the single channel 24 and one of the channels 44 of one dual channel joint are one and the same element. In essence, FIG. 11 depicts a compound corner connection for the shielded enclosure involving two of the double channel joints of FIG. 5 connected at right angles with a descending right angular joint of the kind shown in FIG. 4, and one of the single channel joints of FIG. 3 extending away from and being an extension of one dual channel joint 44--44. 
     In addition to enabling the construction of a completely shielded enclosure around various obstructions, the described splices formed in the several joints enables the making of separated sub-assemblies which are easily transportable to a required location where the enclosure can be erected in an expeditious manner. The unique advantages of the invention over the known prior art should now be readily apparent to those skilled in the art. 
     The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof but it is recognized that various modifications are possible within the scope of the invention claimed.