Door frame assembly for electrical enclosure

Abstract: An electrical enclosure having a housing including a door. The electrical enclosure includes a frame assembly and a plurality of fasteners. The frame assembly has a first side including a planar portion opposite door. The plurality of fasteners are disposed through frame assembly for mounting the frame assembly to the door such that the fasteners do not protrude beyond the plane of the planar portion.

Description: FIELD OF THE INVENTION The present invention relates generally to door frame assemblies, and more particularly, to frame assemblies for supporting doors of electrical enclosures. BACKGROUND OF THE INVENTION Electrical enclosures typically include an outer housing and a door and are manufactured of a plastic or a metal, such as steel. The outer housing and door form an enclosure which houses electrical components, such as switches. The door is typically made of sheet metal having sufficient strength to avoid unwanted contamination of the electrical components by dust or water. These doors lack rigidity, and, especially with larger doors, may be perceived to be flimsy and thus cheap by some customers. Moreover, it has become desirable to mount electrical accessories to the inner side of the door. Sheet metals doors generally lack the rigidity and mounting surface necessary to durably and easily accommodate such accessories. To increase the rigidity of electrical enclosure doors and to facilitate mounting of accessories, door-support frame assemblies, such as the assembly disclosed in German Patent No. 41 03 785 C2 to Reuter, have been used. These frame assemblies typically include a pair of vertical tubular members, a pair of horizontal tubular members and four corner fasteners, which interconnect the vertical tubes with the horizontal tubes to form a generally rectangular frame assembly. The frame assembly is mounted to the inner side of the door using a number of threaded nut and bolt assemblies. To facilitate the mounting of accessories, the frame assembly is provided with bore holes along its tubes for mounting accessories on the frame assembly Typically, a number of threaded bolts are mounted to the inner side of the door and are received by holes in the frame assembly. The holes also receive internally threaded nuts, which are provided with guide sleeves onto which a washer is placed. The guide sleeves then receive the threaded bolts so that the nuts can be screwed to the bolts to mount the frame assembly to the door. Typically, a threaded nut and bolt assembly is used in each corner of the frame assembly and in the middle of the vertical tubes if the cabinet is tall. However, in these frame assemblies, the threaded nuts protrude from the outer plane of the frame assembly. The protruding nuts limit the ability to mount accessories and also catch on objects, such as a user's clothes. An example of such a frame assembly with nuts protruding the frame assembly is known from DE 295 16 362 U1. The frame assembly is mounted on the door of a housing by fixing the assembly at the four corners with nuts extending into bolts mounted on the door. Another example for an electrical enclosure with a housing including a door with a frame assembly is disclosed in EP 0 583 856 A1. A plurality of bolts are mounted on the door and a plurality of nuts are disposed through the frame assembly. The nuts do not protrude the planner surface of the frame assembly. The disadvantage of this embodiment is that several frame parts are connected together with overlapping thin metal sheets. The metal sheets are mounted on the frame parts with protruding screws. Consequently, there is a need in the electrical enclosure industry for a door-support frame assembly which increases the rigidity of the door and provides an unobstructed surface for mounting accessories. The present invention addresses this and other needs associated with frame assemblies. SUMMARY OF THE INVENTION The present invention is directed to an electrical enclosure having a housing including a door with the features of claim 1. The electrical enclosure includes a frame assembly and a plurality of fasteners. The frame assembly has a first side including a planar portion opposite the door. The plurality of fasteners are disposed through the frame assembly for mounting the frame assembly to the door such that the fasteners do not protrude beyond the plane of the planar portion. Additionally, the frame assembly includes a plurality of corner members each having a pair of legs for interconnecting the vertical and horizontal tubes of the frame assembly and having a central mounting portion disposed between the two legs. The mounting portion defines a bore for receiving a corresponding stud. The mounting portion further includes a recess configured to receive a corresponding head of the fastener such that the fastener does not protrude beyond the planar surface of the frame assembly and the recess is sized to allow movement of the studs therein. These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtaining by its use, reference should be made to the drawings which form a further part hereof, and the accompanying descriptive matter in which there is illustrated and described some preferred embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a perspective view of an electrical enclosure having a frame assembly in accordance with the principles of the present invention; Figure 2 shows a perspective view of a corner of the frame assembly shown in Figure 1, illustrating how it mounts to a door; Figure 3 shows a detailed perspective view of a section of the tube for the frame assembly shown in Figure 1, illustrating how the tube mounts to a door; Figure 4 shows a side elevational view of a section of a tube shown in Figure 1; Figure 5A shows a cross-sectional view taken along line 5A-5A of Figure 4; Figures 5B shows a cross-sectional view taken along line 5B-5B of Figure 4; Figure 5C shows a cross-sectional view taken along line 5C-5C of Figure 4; Figure 5D shows a cross-sectional view of an opening of Figure 5A having a fastener and stud mounted therein; Figure 6 shows a perspective view of a corner member of Figure 1; Figure 7 shows a cross-sectional view of the corner member of Figure 6 fastened to a door; and, Figure 8 shows an elevational view of the corner member of Figure 6. DETAILED DESCRIPTION OF THE EMBODIMENTS Referring now to the drawings, and more particularly to Figure 1, an exemplary frame assembly 10 mounted to a door 42 of an electrical enclosure 40 is shown. Frame assembly 10 includes four corner members 30, four tubular members or tubes 12, a pair of which are vertical and a pair of which are horizontal, and a plurality of fasteners 50. Each corner member 30 interconnects a vertical tube 12 with a horizontal tube 12 to form a typically rectangular frame assembly 10 as shown. Frame assembly 10 includes a first side opposite door 42 and a second side facing door 42, the first side having a substantially planar surface. Tubes 12 may be constructed of plastic or metal, and in the exemplary embodiment, comprise preplated, rolled 20 gauge steel. Corner members 30 may be constructed of plastic or metal, and, in the exemplary embodiment, are comprised of zinc. Metal tubes and corner members enhance the ability to ground frame assembly 10 and thus simplify mounting of electrical accessories. Frame assembly 10 may be mounted to door 42 using studs 44 and fasteners 50 as shown in Figures 2 and 3. Fasteners 50 may comprise threaded, flathead screws each having a head 52 with a tapered edge 53. Studs 44 are typically welded to door 42 and may be cylindrically shaped and internally threaded for threadably receiving fasteners 50. It is noted, however, that in alternate embodiments, studs 44 may be externally threaded bolts and fasteners 50 may be internally threaded nuts accompanied with cylindrical sheaths. In the exemplary embodiment, one stud 44 is provided in each corner of door 42 for mounting frame assembly 10 through its corner members 30, and one stud 44 is provided with each vertical tube 12 for mounting vertical tubes 12 to door 42. Studs 44 are typically positioned such that frame assembly 10 lies a given distance from the edge of door 42, so that sufficient room is provided for mounting hinges and a lock. It is noted that with smaller enclosures, mounting of vertical tubes 12 is not necessary, and frame assembly 10 may be sufficiently mounted to door 42 by mounting through corner members 30 only. Turning now to Figures 4 and 5A-D, there is shown an exemplary tube 12. In the exemplary embodiment, vertical and horizontal tubes 12 are manufactured by rolling and thus include a rolled portion 21. Tubes 12 further include a first side 23 opposite door 42 and a second side 25 facing door 42. Each vertical tube 12 may be provided with an opening 14 passing through first side 23 and second side 25 for receiving a fastener 50 and a stud 44. Fastener 50 passes through first side 23 and stud 44 passes through second side 25 and receives fastener 50 in order to mount vertical tubes 12 to door 42 as best shown in Figures 3 and 5D. As shown in Figure 5A, opening 14 may have a smaller diameter on the first side 23 than on the second side 25, since, in the exemplary embodiment, the second side 25 of opening 50 receives a stud 44 having a diameter larger than that of the fastener 50 which is received by the first side 23. In the exemplary embodiment, openings 14 are disposed at the midpoint of vertical tubes 12. However, opening 14 can be disposed in other places along vertical tubes 12, or, more than one opening 14 may be provided in each vertical tube 12, if so desired. Moreover, though typically not required, one or more openings 14 may be provided in horizontal tubes 12. It is noted that in the exemplary embodiment, horizontal tubes 12 are similar to vertical tubes 12, save that horizontal tubes 12 are generally not mounted to door 42 and thus are not provided with openings 14. It should be appreciated that first side 23 of tubes 12 has a substantially planar surface with the exception of holes, i.e., the surface of first side 23 is substantially flat. As best shown in Figures 5A and 5D, vertical tubes 20 may be provided with a countersunk region 16 surrounding openings 14. As shown in Figure 5A, countersunk region 16 may be initially coplanar with the plane of the planar portion of vertical tube 12 and, as shown in Figure 5D, when frame assembly 10 is mounted to door 42, countersunk region 16 yields so as to be depressed relative to the plane of the planar portion such that fasteners 50 do not protrude beyond the plane of the planar portion. In this manner, countersunk region 16 allows fastener 50 to be self-countersinking. With reference to figure 5D, it can be seen that countersunk region 16 cooperates with an upper end 45 of stud 44 to limit the depth to which fastener 50 is received by stud 44. Prior to tightening of fasteners 50, upper end 45 is initially spaced a distance from the first side 23 of tube 12. As shown in figure 5D, when frame assembly 10 is mounted to door 42, countersunk region 16 yields until it abuts upper end 45. The initial spacing between first side 23 of tube 12 and upper end 45 of stud 44 may be provided such that the depth to which fastener 50 is received is limited so that when frame assembly 10 is mounted to door 42, fastener 50 lies flush with the plane of the planar portion of the tube 12. It should further be appreciated that tapered edges 53 of fastener 50 cooperate with countersunk region 16 to provide a substantially continuous planar surface formed by tubes 12 and fastener heads 52. Tubes 12 may further be provided with holes 24, as shown in Figures 4 and 5B, for mounting accessories to the inner side of door 42. Holes 24 need only be provided through first side 23, and may be spaced equidistant along the length of tube 12. It should be apparent that an edge of first side 23 of tubes 12 forms the perimeter of each hole 24. In the exemplary embodiment, the edge may extend inwardly to form a lip 27 for providing additional strength with which to hold mounted accessories. An additional two holes 26 extending through both first side 23 and second side 25 may be provided to allow an external mechanism (not shown) to grip and position tubes 12 for crimping or otherwise connecting them to corner members 30. Referring now to Figures 6, 7 and 8, there is illustrated an exemplary one of corner members 30. To facilitate mounting and assembly, exemplary corner members 30 are interchangeable. Each corner member 30 includes a mounting portion 32 and a pair of legs 36 extending from mounting portion 32. Mounting portion 32 may include raised portions 31 and a recess 35, the purpose of which will become apparent hereinafter. Legs 36 are each received by a corresponding vertical or horizontal tube 12. Though corner members 30 having a pair of legs are exemplified herein, it is noted that mounting portion 32 may be provided with more than two legs 36 for interconnecting more than two tubes 21, e.g., where a lattice framework is desired. The cross-section of each leg 36 is stepped down from the mounting portion 32 to form a lip 38 for limiting the depth to which a leg 36 is received by a tube 12. Moreover, in the exemplary embodiment, the depth of lip 38 is sized to the thickness of tubes 12 such that tubes 12 lie flush with raised portions 31 of corner members 30. Thus, the upper surface of raised portions 31 lies in the same plane as that formed by first side 23 of tubes 12. For securely connecting legs 36 and tubes 12, each leg 36 is provided with indentations 37 on one of its sides, for example, an outwardly facing side as shown. After a tube 12 receives a leg 36, it can be crimped into the indentations 37 for securing a connection therebetween. It is noted that crimping is only exemplary, and that, in alternate embodiments, the tubes and corner members may be connected by press-fitting, bolting, etc. Moreover, frame assembly 10 may be crimped or otherwise connected together prior to or after mounting to door 42. As shown in the perspective view of Figure 6, each leg 36 may include a recess 39 for receiving rolled portion 21 of tubes 12. Each leg 36 may further include grooves 62 separated by supports 60. Grooves 62 and supports 60 are desirable for decreasing the weight of frame assembly 10 and increasing its strength-to-weight ratio, and in addition, for facilitating the boring of holes 24 through a corner member 30, if so desired. Mounting portion 32 of each corner member 30 defines a bore 34 provided to receive a stud 44 and a fastener 50 for mounting frame assembly 10 to door 42. Bore 34 may be circular and may have a diameter larger than the diameter of stud 44 such that there is play in bore 34, i.e., stud 44 and fastener 50 may move within bore 34, to account for mechanical tolerances in the construction, assembly, and mounting of frame assembly 10 to door 42. Though bore 34 may take any number of shapes, in the exemplary embodiment, bore 34 is circular, As indicated above, mounting portion 32 may also be provided with recess 35 for receiving head 52 of a fastener 50 so that head 52 does not protrude from the plane of frame assembly 10. Moreover, recess 35 may be provided with a depth which limits the distance to which fastener head 52 is received so that a fastener head 52 lies flush with the plane of frame assembly 10. Fastener 50 may additionally be provided with a washer 54. As best shown in Figures 7 and 8, washer 54 may be circular and have an outer perimeter 55 with a triangular cross-sectional area. It should be appreciated that the inner surface 56 of outer perimeter 55 of washer 54 may be provided with a taper which mates with the tapered edge 53 of fastener head 52. As shown in Figure 8, recess 35 may be sized larger than fastener 50 such that a gap 33 exists between raised portions 31 and washer 54 and/or fastener head 52 to allow movement of fastener 50 within recess 35. Gap 33 also provides play in corner members 30 to account for mechanical tolerances. An exemplary method for assembling and mounting the frame assembly includes first sliding the ends of each tube 12 over a respective corner member leg 36 and then crimping each tube 12 and corresponding leg 36 together. Following this, frame assembly 10 is positioned on the inner side of door 42 such that studs 44 are each received by a corresponding opening 13 or bore 36. Next, vertical tubes 12 are fastened to door 42, then corner members 30 are fastened to door 42. It is noted that with the self-countersunk, countersunk regions 16, vertical tubes, once fastened, are fixed. Consequently, the play provided by bores 34 and gaps 33 is desirable. This assembly and mounting method is exemplary only and many other methods may be used. For example, corner members 30 an legs 36 may be connected after frame assembly 10 is positioned on door 42 or after vertical tubes are fastened to door 42. It will, of course, be understood that modifications can be made to the embodiments described herein above within the scope of the present invention. For example, the frame assembly may be employed in any type of enclosure having a door, for example, lockers, tool cabinets, etc.

Claims: Electrical enclosure (40) having a housing including a door (42), comprising: a frame assembly (10) including at least vertical and horizontal tubes (12) having a planar surface (23) opposite the door (42); a plurality of studs (44) mounted to the door (42); a plurality of fasteners (50) including a head (52) and disposed through the frame assembly (10), whereby said fasteners (50) are mounted to the studs (44) such that the fasteners (50) do not protrude beyond the planar surface (23); characterized by the frame assembly (10) further including a plurality of corner members (30), each corner members (30) having: a pair of legs (36) for interconnecting the vertical and horizontal tubes (12); and a central mounting portion (32) disposed between the two legs (36), said mounting portion (32) defining a bore (34) for receiving a corresponding one of said studs (44), and said mounting portion (32) includes a recess (35) configured to receive a corresponding one of the heads (52) of said fasteners (50) such that the fastener (50) does not protrude beyond the planar surface (23) of said frame assembly (10), wherein said recess (35) is sized to allow movement of the studs (44) therein. Electrical enclosure according to claim 1, characterized in that the central mounting portion (32) includes raised portions (31) disposed about a periphery of said recess (35) and extending to the planar surface (23) such that the upper surface of said raised portions (31) lies in the same plane as that formed by said surface (23).

Inventors: KERN KLAUS, LAU ROBERT G, RIEGER UWE, WICK HENNING, KERN, KLAUS, LAU, ROBERT G., RIEGER, UWE, WICK, HENNING
Applicants: HOFFMAN ENCLOSURES INC, HOFFMAN ENCLOSURES INC.
Application year: 1997
Main classification: H02B1
IPC codes: H02B1, H05K5, E06B3