Abstract:
An electrical busway housing system mechanically connected at the joints of adjoining housing sections by utilization of a coupling system having a top plate and a bottom plate, at least one of which has a roughened surface that provides superior gripping strength when the adjoining sections of busbar housing are clamped between them. Frictional clamping force is provided by a means of drawing the top plate and the bottom plate together and securing between them flanges or similar structural features of the busbar housing.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to an electrical busway housing system capable of conducting electricity and mechanical connection means therefor, and more particularly, to an electrical busway housing system mechanically connected at the joints of adjoining housing sections by utilization of a coupling system having a top plate and a bottom plate, at least one of which has a roughened surface that provides superior gripping strength when the adjoining sections of busbar housing are clamped between them.  
         BRIEF DESCRIPTION OF PRIOR ART  
         [0002]    Electrical busway, also known as elongated electrical distribution busway, is well known in the art. An electrical busway housing system is typically comprised of multiple pieces of track connected end to end with one or more electrically-isolated, conductive busbars fastened to the housing, such that the system is capable of conducting electricity end to end through the busbars. The busbar is adapted to permit electrical power tap-off at any point along the length of the busbar. Such busbar is often provided overhead, or may be provided along walls or flooring, and is used to distribute electricity to various take-off devices to equipment, appliances, lighting or other articles requiring a source of electrical energy to operate. For example, when installed in a home or office setting, it is often used to permit lighting and/or electrical sockets to be placed in one or more locations along the electrical busway. When installed in a factory or other industrial application, electrical sockets, lighting or other industrial devices may be placed on, near or along the busway to obtain electrical current from the busway.  
           [0003]    Electrical power distribution tracks or busways are typically comprised of an elongated housing containing multiple electrically isolated conductive busbars. Sections of the track can be joined together to form long runs for the power distribution, and such sections may be of any length, but are generally anywhere from two (2) to twenty (20) feet long each. The joining of two twenty foot sections to one another, for example, provides 40 feet of electrical busbar, and the process can be repeated as necessary to provide electrical busway of substantial length.  
           [0004]    While not limited to the use of aluminum housings, aluminum busbar housing generally tends to be the housing of choice due to its light weight, great strength and economical cost and ease of manufacture.  
           [0005]    The joining of the individual sections must provide for making both mechanical and electrical connections from one section of housing to the adjoining section. This is generally accomplished with a coupler, also known, among other terms, as a coupling system, a connecting system, a coupling assembly, or a connector assembly. There are several known approaches to this coupling system. Examples include U.S. Pat. No. 2,969,421, to Sott, Jr; U.S. Pat. No. 3,210,716 to Meacham; U.S. Pat. No. 3,509,514 to Christensen et al.; U.S. Pat. No. 6,039,584 to Ross and U.S. Pat. No. 6,105,741 to Ross, with certain of these patents focusing on the mechanical connection, the electrical connection or both.  
           [0006]    Referring now to FIG. 1A there is illustrated a coupling system of the prior art which uses a pair of flat plate connector assemblies  2  and  4 . Two sections of busway  6  and  8 , shown in phantom in FIG. 1A can be connected by using the two flat plate connector assemblies  2  and  4 , that sandwich a flange or similar feature at the ends  10  and  12  of the busway housing. Flat plate connector assemblies of the type of flat plate connector assemblies  2  and  4  are usually used in two sets, either top and bottom or side and side. Referring to both FIG. 1A and FIG. 1B, such flat plate connector assemblies of the type of flat plate connector assemblies  2  and  4  are each composed of a flat bottom plate  14  having a pair of throughholes  16  therethrough which may or may not be threaded, and a corresponding top plate, in this case the u-shaped top plate  18 . The unshaped top plate  18  includes throughholes  20  therethrough, which may or may not be threaded. Bolts  22  and  23  are typically inserted through the throughhole  20  and  21  respectively of u-shaped top plate  18 , and into the corresponding throughhole  16  and  17  in flat bottom plate  14  whereupon, if the throughhole of the flat bottom plate is threaded, said bolt threadably engages said threaded throughhole, allowing the bolt to be tightened in order to draw the unshaped top plate and the flat bottom plate together over the flanges at the ends  10  and  12  respectively of the busways  6  and  8 . If the throughhole of the flat bottom plate  14  is not threaded, a nut  26  is threadably engaged with the bolt  22  to draw the flat bottom plate  14  and the unshaped top plate  18  together. The frictional force between the flat bottom plate  14 , the u-shaped top plate  18  and the flange of the respective housings  6  and  8  is intended to keep the adjoining housings  6  and  8  from separating. However, under loads, particularly where the housings  6  and  8  are supported overhead and span a substantial distance, the housings  6  and  8  tend to pull apart overtightening bolts  22  to provide additional compressive force generally results in stripping the threaded throughholes or nuts damaging and/or destroying the connector assembly.  
           [0007]    Referring now to FIG. 2 there is illustrated a known wrap-around type connector  30 . In this design, an aluminum extrusion  32  telescopes over the ends of housings  6  and  8  shown in phantom that are joined. Wrap-around connector  30  has two bolts  34  and  35  that tighten a plate  36  to create a frictional clamping force as described above in connection with the flat plate coupling assemblies  2  and  4 . However, as may be appreciated, most of the support comes from the telescoping or wrap-a-round effect rather than the frictional clamping force.  
           [0008]    Illustrated in FIG. 3 is yet another known connector generally referred to as a channel and set screw connector  40 . An extruded piece of aluminum channel  42  is designed to slide loosely into each end of a pair of busbar housings  6  and  8  in phantom, where channels  44  and  46  engage corresponding lips on each of the busbar housings  6  and  8 . Once the busway housings  6  and  8  are butted together, and the connector  40  is centered over the gap interface between the two housings  6  and  8 , two or more setscrews  48  and  49  are tightened in throughholes through the connector  40  and through a corresponding channel in each housing corresponding to the lip  50  of the connector  40  in order to secure both the connector  40  and the two housings in place. Although the setscrews  48  and  49  keep the connector  40  from moving and the shape of the extrusion provides some support for keeping the two housings in line, particularly when the housings are supported overhead, the amount of gripping frictional force in this design to prevent separation of the housings is minimal.  
           [0009]    All of the known embodiments described above suffer from the limitation that where the busbars housings are joined, particularly but not limited to larger busway systems (e.g. greater than 100 amps), where the busbar housings are installed overhead or along a wall the above described connectors provide insufficient force to hold the busbars tightly together. For example, this is particularly true for large busway systems supported overhead from a ceiling or other structure where the supports are placed at greater intervals from one another (e.g. 10 foot intervals versus 5 foot intervals). Greater spacing intervals between the supports is generally desired as fewer supports are needed to support the busway system as a whole, but as pointed out above, the known connectors between busway housing sections, particularly for the larger busway systems, cannot provide sufficient force to hold the busbar sections together over greater spacing intervals. For example, such designs typically cannot meet a United Laboratories Resistance to Bending Test 857-45, which uniformly tests the ability for such housings to withstand bending loads over such connectors.  
           [0010]    There remains a strong felt need in the art for an electrical busbar housing system, and in particular a busbar housing coupling system that has greater resistance to bending at the joints where adjoining sections of housing are fastened together, end to end and are supported at as great an interval between supports as is practicable.  
         SUMMARY OF INVENTION  
         [0011]    Accordingly, a primary object of this invention is to provide an electrical busway housing system that has greater strengths, greater load-carrying capabilities and greater resistance to bending, thereby enabling such housing systems to be mounted with hangers at greater intervals than are presently possible. The greater the strength of the system at a joint between adjoining housing sections, the greater the allowable distance between hangers from which the electrical busway housing system is hung.  
           [0012]    The essence of this invention is an improved and novel coupling system. In the prior art, particularly the coupling systems illustrated in FIGS.  1 A- 3  and described above, a top plate and bottom plate are paired and operate to grip adjoining busway housing sections together and the top and bottom plates that are utilized to create the gripping force are smooth. In contrast, in the present invention a coupling system is disclosed with a markedly roughened surface on an area of one or more those portions of the top and/or bottom plate that are intended to contact and grip the busway housing. The components having such a roughened surface are preferably formed of a selected material which indents the contacted surface of the busway housing, thereby substantially increasing the amount of gripping force and increasing substantially the force necessary to separate the joined housing sections.  
           [0013]    The roughened surface operates to increase the co-efficient of friction between the busway housing section and the top and/or bottom plates. The roughened surface may be in the form of serrations or other indentations on the surfaces of the top and/or bottom plates contacting the busway housing sections, or may be in the form of materials adhered to or formed within the surfaces, such as grits or other materials. The materials adhered to the surface may be adhered by any known process, including welding, soldering, brazing, chemical or other adhesives and the like. A particularly preferred embodiment comprises serrations in either the top or bottom plate of a material sufficiently rigid to deform the busway housing section when the busway housing section is clamped between the top and bottom plate. In an alternative embodiment of the present invention, the busway housing itself may also include a roughened surface on that portion of its surface contacting the top and bottom plates to further increase the co-efficient of friction between the top plate, bottom plate and the busway housing section gripped therebetween.  
           [0014]    In one embodiment of the invention, the connecting assembly of the present invention is used to connect the bottoms of the adjoining housing sections together, but not the tops of the adjoining housing sections. In an alternative embodiment of the present invention connecting assembly of the present invention is used to connect the tops of the adjoining housing sections together but not the bottoms. In yet another embodiment of the present invention the novel connecting assembly of the present invention is used on both the top and bottom portion of interface between the two housing sections. Finally, as may be appreciated, the novel connecting assembly of the present invention may be used with wrap-around type connector assemblies illustrated in FIG. 2 as well the orientations of top, bottom and side are generally illustrated in FIG. 1A.  
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0015]    [0015]FIG. 1A is perspective view of a pair of prior art flat plate connector assemblies being used at the interface between two busbar housings to join the two busbar housings together.  
         [0016]    [0016]FIG. 1B is a perspective view of one of the prior art flat plate connector assemblies of FIG. 1A, separating the components of the flat plate connector assembly to more fully illustrate the design of each component.  
         [0017]    [0017]FIG. 2 is a perspective view of a prior art wrap-a-round connector assembly  
         [0018]    [0018]FIG. 3 is a perspective view of a prior art channel/set screw connector assembly.  
         [0019]    [0019]FIG. 4 is a perspective view illustrating a roughened bottom plate and top plate of a connector assembly of the present invention.  
         [0020]    [0020]FIG. 5A is a top plan view of the top plate of a connector assembly of the present invention.  
         [0021]    [0021]FIG. 5B is a side elevational view of the top plate of the connector assembly of the present invention.  
         [0022]    [0022]FIG. 6A is a top plan view of the roughened bottom plate of the connector assembly of the present invention.  
         [0023]    [0023]FIG. 6B is a side elevational view of the roughened bottom plate of the connector assembly of the present invention.  
         [0024]    [0024]FIG. 6C is a side elevational view of an enlargement of a portion of the roughened bottom plate of FIG. 6B.  
         [0025]    [0025]FIG. 7 is a perspective view illustrating an assembly of one embodiment of this invention illustrating the connection of two sections of busbar housing with the novel connector assembly of the present invention.  
         [0026]    [0026]FIG. 8 is an elevational sectional view along the line VIII-VIII in FIG. 7.  
         [0027]    [0027]FIG. 9 is an elevational sectional view along the line IX-IX in FIG. 8. 
     
    
     DETAILED DESCRIPTION OF INVENTION  
       [0028]    In the following discussion, unless otherwise clear from the context of use, when used in reference to a surface of a component of the present invention, the word “outer” refers to surfaces that have no direct contact with the busway housing when the invention is installed to connect two sections of busway. Conversely, when so used, the word “inner” refers to surfaces that have at least some portions thereof in direct contact with the busway housing when the invention is so installed. “Inner” surfaces of the components of the invention face each other when the invention is installed to connect two sections of busway housing. “Top”, “bottom” and “side” orientations are indicated in FIG. 1A and the terms are applied in a similar fashion throughout the following discussion.  
         [0029]    To the extent necessary for an appreciation of the present invention, U.S. Pat. Nos. 6,039,584 and 6,105,741 both to Ross, and United Laboratories&#39; Resistance To Bending Test 857-45 are hereby incorporated herein in their entities.  
         [0030]    Referring now to FIG. 4 and in a view similar to FIG. 2, there is shown an embodiment of the present invention consisting of a busway housing connection assembly  50  comprising a top plate  52  having four throughholes  54 ,  56 ,  58  and  60  therethrough. Top plate  52  is illustrated as a u-shaped channel, but as may be appreciated the present invention is not so limited and the top plate may be a flat plate, a u-shaped channel or any other type of plate that will operate to cooperate with a bottom plate  62  described immediately below to grip a section of busway housing therebetween. Also illustrated in FIG. 4 is bottom plate  62  having a roughened inner surface  64  and four throughholes  66 ,  68 ,  70  and  72  therethrough which align and correspond with throughholes  54 ,  56 ,  58  and  60  respectively in top plate  52 . Throughholes  66 - 72  in bottom plate  62  may or may not be threaded to receive four bolts  74 ,  76 ,  78  and  80  respectively. If said throughholes  66 - 72  in bottom plate  62  are threaded, bolts  74 - 80  may be inserted through the throughholes  54 - 60  in top plate  52  and threadably engaged in said throughholes  66 - 72  in bottom plate  62  and turned in order to draw top plate  52  and bottom plate  62  together. However, the invention is not limited to the use of  4  bolts to draw top plate  52  and bottom plate  62  together, and more or less bolts or screws, or rivets may also be used to draw the bottom plate  62  and the top plate  52  together. Where the throughholes  66 - 72  in bottom plate  62  are not threaded, top plate  52  and bottom plate  62  may be connected and drawn together by the use of nut and bolt assemblies or rivets for example.  
         [0031]    As discussed below, the invention is not limited to embodiments in which the inner surface of the bottom plate  62  is roughened. In other embodiments, discussed below, only the inner surface of the top plate  52  is roughened. In yet other embodiments, the inner surfaces of both the top plate  52  and the bottom plate  62  are roughened.  
         [0032]    The top plate  52  and bottom plate  62  may be manufactured of any suitable material providing sufficient strength and rigidity to firmly hold two sections of busway together when the busway housing connection assembly  50  is installed. However, when either the top plate  52  or the bottom plate  62  is manufactured with a roughened inner surface such as surface  64  of bottom plate  62  illustrated in FIG. 4, it is preferably manufactured of a material that is harder than the busway housing, so that the roughened inner surface of the top plate  52  or the bottom plate  62  respectively will indent the flanges or similar features of the busway housings  6  and  8  when said flanges or similar features are clamped between top plate  52  and bottom plate  62  and top plate  52  and bottom plate  62  are drawn together by tightening bolts  74 - 80 , thus providing increased gripping force and strengthening the connection. In a most preferred embodiment, the busway housings  6  and  8  are made of aluminum and the top plate  52  and/or the bottom plate  62  are made of steel.  
         [0033]    In an alternative embodiment of the invention not shown, all or part of the inner surface of the top plate  52  is also roughened, so that both the bottom plate  62  and the top plate  52  will increase the gripping force and the strength of the connection.  
         [0034]    In yet another alternative embodiment, only top plate  52  is manufactured with a roughened inner surface contacting the busway housing.  
         [0035]    [0035]FIGS. 5A and 5B show top plate  52  having the four throughholes  54 - 60  therethrough. FIG. 5A is a top view of top plate  52  showing the outer surface, while FIG. 5B is a side view of same. FIG. 5B includes arrows  82 ,  84 ,  86  and  88  illustrating the position of throughholes  54 - 60 .  
         [0036]    [0036]FIGS. 6A and 6B show bottom plate  62  having the four throughholes  68 - 72  (corresponding to throughholes  54 - 60  through top plate  52  as shown in FIGS. 5A and 5B). FIG. 6A is a top plan view of bottom plate  62  showing the roughened inner surface  64 , while FIG. 6B is a side elevated view of same.  
         [0037]    [0037]FIG. 6C is an enlarged side elevated view of the circle portion  90  of bottom plate  62  illustrated in FIG. 6B, showing in more detail the roughened inner surface  64 .  
         [0038]    [0038]FIGS. 4, 5A, and  5 B all depict embodiments of top plate  52  having four throughholes  54 - 60  therethrough. Likewise, FIGS. 4, 6A, and  6 B all depict bottom plate  62  having four throughholes  66 - 72  therethrough to accommodate four bolts to draw top plate  52  and bottom plate  62  together. These illustrations are exemplary only. Other embodiments of the invention may have more or fewer throughholes with an equal number of bolts or alternative fastening devices, as may be deemed necessary to provide sufficient connecting force between top plate  52  and bottom plate  62 . All such embodiments are included within the scope of the present invention and include bolts into threaded throughholes  64 - 72 , bolt and nut assemblies throughholes  54 - 60  and  66 - 72 , or screws or rivets or any similarly functioning devices which operate to draw bottom plate  62  and top plate  52  together.  
         [0039]    [0039]FIGS. 4, 6A,  6 B, and  6 C depict bottom plate  62  having the roughened surface  64  in the form of serrations formed by pointed ridges running from side to side. However, as may be appreciated, the surface of either bottom plate  62  or top plate  52  may be roughened by any structural feature that will provide increased frictional gripping force on the flange or similar feature of the busway housing when the bolts  74 - 80  or other fastener connecting top plate  52  and bottom plate  62  are tightened. For example, and without limiting the scope of the invention, bottom plate  62  and/or top plate  52  may be manufactured with cone-shaped or other shaped teeth, and/or with friction increasing granules or films adhered therein or thereon to form the roughened surface  64 . All embodiments of bottom plate  62  and top plate  52  having a roughened surface are within the scope of the present invention, regardless of the manner in which the surface is roughened.  
         [0040]    In addition, it is not necessary that the entire inner surface of either bottom plate  62  or top plate  52  be roughened, as long as portions of said inner surface that are in direct contact with the busway housings  6  and  8  when installed are roughened. Accordingly, embodiments of bottom plate  62  and top plate  52  having only portions of the surface  64  that are roughened are likewise within the scope of the present invention.  
         [0041]    In an alternative embodiment, both top plate  52  and bottom plate  62  have all or parts of their inner surfaces roughened so that the increased frictional gripping force is applied to both sides of the flange or other feature of the busway housings  6  and  8  when the invention is installed.  
         [0042]    In a preferred embodiment, both top plate  52  and bottom plate  62  are manufactured of a selected material that is harder than the busway housings  6  and  8 . Also in a preferred embodiment, where both of the surfaces of the top plate  52  and the bottom plate  62  contacting the busway housings are roughened, the structural features that form the roughened surfaces  64  of top plate  52  and bottom plate  62  fit together or overlap one another, as, for example, where the roughened surfaces are in the form of interlocking pointed ridges or teeth, such that the roughened surfaces of top plate  52  and bottom plate  62  cooperate to crimp the flange or similar feature of the busway housing when bolts  74 - 80  are tightened and top plate  52  and bottom plate  62  are drawn together.  
         [0043]    [0043]FIG. 7 illustrates two busway housing connector assemblies  100  and  102  being installed to connect two busway housing sections  6  and  8 . FIG. 8 illustrates the busway housing connector assemblies in cross section as installed at the end of a section of busway housing along the line VIII-VIII of FIG. 7. FIG. 9 illustrates the busway housing connector assemblies  100  and  102  in longitudinal cross section as installed at the end of a section of busway housing along the line IX-IX of FIG. 7.  
         [0044]    As illustrated in FIGS. 7, 8 and  9 , in order to connect two sections of busway housing  6  and  8 , one bottom plate  104  is inserted up to approximately half of its length into the top recesses  106  formed by the upper inwardly projecting flanges  110  and  112  and roof member  114  at the top of busway housing  8 . A top plate  116  is then placed over bottom plate  104  and upper inwardly projecting flanges  110  and  112  with the sides  118  and  120  of the u-shaped portion extending downwardly along the sides  122  and  124  of the busway housing  8 . Bolts  126  and  128  are inserted through the throughholes  127  and  129  respectively of top plate  116  and loosely screwed into the threaded throughholes  130  and  132  of bottom plate  104 . Another bottom plate  134  is likewise inserted up to approximately half of its length into the bottom recess  136  formed by the lower inwardly projecting flanges  138 - 144  at the bottom of busway housing  8 . Another top plate  146  is then fitted over the bottom plate  134  and lower inwardly projecting flanges  138  and  140  with the sides  148  and  150  of the top plate  146  extending upwardly along the sides  152  and  154  of the busway housing  8 . Again, bolts  156 ,  158 ,  160  and  162  are inserted through the throughholes  164 ,  166 ,  168  and  170  in top plate  146  and loosely screwed into the threaded throughholes  174 - 178  of bottom plate  134 . The second section of busway housing  6  can then be fitted into the interstitial spaces  180  and  182  respectively between the top plate  116  and bottom plate  104  and the top plate  146  and the bottom plate  134  by sliding the flanges of busway housing  6  corresponding to upper inwardly projecting flanges and lower inwardly projecting flanges of busway housing section  8  into said spaces  180  and  182 . When the two busway housing sections  6  and  8  are firmly butted against each other, the busway housing connector assemblies  100  and  102  are manually centered over the connection joint and bolts  126 ,  128 , and  156 - 162  are firmly tightened, drawing the respective top plates and bottom plates of the connector assemblies  100  and  102  together, so that upper inwardly projecting flanges and lower inwardly projecting flanges of both sections of busway housing sections  6  and  8  are firmly pressed therebetween. The roughened surface  184  of the bottom plate  134  provides heretofore unknown gripping strength to hold the busway housing sections  6  and  8  together. The inventors have found that this embodiment, even without roughening and or all of the remaining busway-contacting surfaces of the top plate  146 , and/or top plate  116  and/or bottom plate  104  contacting the busway housing sections  6  and  8  in the interstitial spaces  180  and  182  respectively, is sufficient alone to cause the joined section to meet and/or surpass United Laboratories&#39; Resistance To Bending Test 857-45. Roughing one or more of the remaining surfaces bounding spaces  180  and/or  182  only increases the ability of the connector assemblies  100  and  102  to hold the busway housing sections  6  and  8  together. The connected busway housing sections  6  and  8  may then be hung or supported by any means known in the art, as for example, by the hanger assemblies  9  illustrated in FIG. 7.  
         [0045]    In another embodiment of the invention, a u-shaped wrap-around channel  32  of the type depicted in FIG. 2 illustrating the prior art is substituted for the top plates  116  and  146 . However, rather than the simple bottom plate  36  used in the prior art, a bottom plate of the present invention with a roughened inner surface cooperates with the u-shaped wrap-around channel  32  to firmly hold the inwardly projecting flanges of two busway housing sections in place when the bolts connecting the u-shaped wrap-around channel  32  and the roughened surface bottom plate are tightened. In other embodiments of the invention, both the inner surface of the bottom plate  36  and the corresponding inner surface of the u-shaped wrap-around channel  32  are roughened. In yet other embodiments, only the inner surface of the u-shaped wrap-around channel  32  is roughened. As with other embodiments of the invention discussed herein, when either component, that is, either the u-shaped wrap-around channel  32  or the bottom plate  36  has a roughened surface, said component is preferably manufactured of a material that is harder than the busway housing sections that are to be connected in order to allow the roughened surface to indent the busway housing. Use of a roughened inner surface bottom plate  36  with a u-shaped wrap-around channel  32  combines the support of the telescoping or wrap-around effect of the u-shaped wrap-around channel  32  known in the prior art with the improved frictional clamping force provided by the roughened inner surface of the bottom plate  36  of the present invention. Roughening the corresponding surface of the u-shaped wrap-around channel  32  only operates to improve the frictional force gripping the busway housing sections to one another. It should be noted that, without limiting the invention to this manner of installation, embodiments employing a u-shaped wrap-around channel  32  are preferably installed such that the bottom plate  36  fits into the recesses formed by the bottom inwardly projecting flanges of the busway housing with the opening of the u-shaped wrap-around channel (corresponding to the top of the “U”) at the top of the busway housing.  
         [0046]    Although this invention has been described in terms of multiple embodiments, it is not intended that the invention be limited to these embodiments. Modification within the spirit of the invention will be apparent to those skilled in the art. The scope of the invention is defined by the claims that follow.