Abstract:
The present invention relates to an assembly including a conduit body for containing and accessing wires. The conduit body includes a housing having a generally continuous outer wall, wherein the wall defines a hollow interior chamber. Also, the wall has at least one opening extending therethrough, and at least one tubular hub projecting from the housing. Each tubular hub communicating with an opening. Additionally, a bushing is supported within each opening in the housing.

Description:
[0001]     This application claims the benefit of U.S. Provisional Application No. 60/696,711 filed Jul. 5, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates generally to a conduit body for containing and accessing electrical wires. More particularly, the invention relates generally to a bushing used in a conduit body that reduces friction for wires being pulled through the conduit body.  
         [0003]     Electrical conduit systems are required in order to safely provide electric power to homes, commercial buildings, and the like. These conduit systems often include long runs of electrical conduit with frequent changes in direction, such as 90° turns, and interruptions with various couplings to accommodate bends or changes in direction. The conduits themselves serve to provide a protective housing for the wires therein and to route these wires throughout the building or other installation as required.  
         [0004]     Conduit bodies are often installed at various locations throughout a conduit system in order to provide access to the wires in the conduits, or to route the wires through a bulkhead, an electrical equipment enclosure, a junction box, or other electrical fixture. Conventional conduit bodies can have openings through one or more side walls, as well as through the upper and lower walls.  
         [0005]     Typically, insulated wires are inserted through an opening in one wall of the conduit body and out through an opening located in another wall of the conduit body. However, the friction caused by rubbing the wires against the inner edges of the conduit body makes it difficult to pull the wire through the conduit housing. While power pullers are used for this purpose, often the wires break while being pulled, leaving a partially pulled wire end that is very difficult to access within the conduit. In addition, when the wire is pulled across the inner edges of the conduit body, the abrasion on the insulation can damage the wire.  
         [0006]     Attempts to minimize such friction associated with the wires rubbing against the inner portions of the conduit body have been less than satisfactory. It has long been known to use wire pulling compounds to lubricate the wire so that it can be more easily pulled through the hubs of the conduit body. However, as may be appreciated, these wire pulling compounds are cumbersome and messy to use. Alternatively, conduit bodies have been manufactured to include roller pins and/or smooth edges about the openings to minimize frictional engagement with the wires. However, such solutions unduly complicate the manufacturing of the conduit bodies and do not assist in minimizing friction in existing conduit bodies previously manufactured without such features.  
         [0007]     Accordingly, it is desirable to provide an assembly having a conduit body with a friction reducing bushing positioned within the openings to the conduit body in order to minimize the friction engagement between the wires and the conduit body.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention relates to an assembly including a conduit body for containing and accessing wires. The conduit body includes a housing having a generally continuous outer wall, wherein the wall defines a hollow interior chamber. Also, the wall has at least one opening extending therethrough, and at least one tubular hub projecting from the housing and communicating with an opening. Additionally, a bushing is supported within each opening in the housing.  
         [0009]     Additionally, other elements may be included as part of the assembly in accordance with the invention. In particular, the bushing can be rotatably supported in the opening. Also, the tubular hub can further include an annular rim projecting into the opening and an annular recess adjacent the annular rim. The bushing can include a first end disposed on a first surface of the annular rim and a second end disposed in the annular recess. The second end of the bushing can include an annular flange, the annular flange including an angled surface for snap-fit engagement of the bushing in the opening. Further, at least a portion of the second end of the bushing can be tapered. Further still, the bushing can be formed from a low friction material, such as PTFE, acetyl polymer and plastic. Yet further, the bushing can be secured within the opening by heat curling at least a portion thereof. Preferably, the housing includes two separate openings, each with a corresponding bushing therein and a tubular hub communicating therewith. Additionally, the housing can be formed in a generally elongate shape with the openings disposed at different ends thereof.  
         [0010]     These and other objects, features, and advantages of this invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]      FIG. 1  is a perspective view, partially in section, of an assembly in accordance with an embodiment of the present invention.  
         [0012]      FIG. 2  is a side cross-sectional view of the assembly of  FIG. 1 .  
         [0013]      FIG. 3  is a side cross-sectional view of the assembly of  FIG. 1  with a wire extending therethrough.  
         [0014]      FIG. 4  is a front perspective view of a bushing from the assembly of  FIG. 1 .  
         [0015]      FIG. 5  is a rear perspective view of a bushing from the assembly of  FIG. 1 .  
         [0016]      FIG. 6  is a cross-sectional view of a bushing from the assembly of  FIG. 1 .  
         [0017]     FIGS.  7  is a cross-sectional view of an alternative bushing in accordance with another embodiment of the present invention.  
         [0018]      FIG. 8  is a cross-sectional view of a portion of the assembly showing the bushing of  FIG. 7  installed therein.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]     The present invention provides an assembly for use preferably in electrical conduit systems for containing and accessing wires. In particular, the assembly allows wires to be pulled through a conduit body without causing damage to the wires or their insulation.  
         [0020]     Referring to  FIGS. 1-3 , one of many different versions of conduit body assembly  10  is shown. Conduit body assembly  10  includes a conduit body  12  which is an elongate generally tubular shaped member formed preferably of metal. The conduit body  12  includes an upwardly extending sidewall  14  having an open upper end  16  and a closed lower end  18 . The lower end  18  of sidewall  14  perimetrically bounds a lower wall  20  of the conduit body  12 . The sidewall  14  and lower wall  20  together define a conduit body interior  22 . The interior  22  may be enclosed by cover (not shown) over open upper end  16 . Sidewall  14  defines at the open upper end  16  a generally oval-shaped smooth planar rim  24 .  
         [0021]     Conduit body  12  further includes a pair of elongate tubular projections or hubs  30  and  32  extending outwardly from conduit body interior  22 . Each hub is an elongate member having an inner end  30   a ,  32   a , and outer end  30   b ,  32   b  and a central bore  30   c ,  32   c  therebetween. The bore  30   c ,  32   c  is in communication with the interior  22  of body  12 . Hubs  30  and  32  serve as points of ingress/egress for wire  40 . Each hub  30 ,  32  defines an access port for such wire  40 . Hubs  30 ,  32  may be internally threaded for accommodation of an externally threaded end of a conduit.  
         [0022]     As particularly shown in  FIG. 3 , conduit body assembly  10  is designed to accommodate an insulated electrical wire  40  therethrough. As is well known in the art, the wire  40  is pulled through the conduit body by using the hubs  30  and  32  as ingress/egress ports. Such movement of the wire  40  through the conduit body  12  may have a tendency to abrade the insulation of the wire as it slides along the inner ends  30   a ,  32   a  of the conduit body  12  at hubs  30  and  32 . Such abrading is particularly prevalent at the point of communication  30   d ,  32   d  between the hubs and the conduit body interior.  
         [0023]     In order to reduce the friction between the conduit body and the wire  40  being pulled therethrough, a reduced friction surface in the form of a bushing  50  is provided at the inner ends  30   a ,  32   a  where the hubs  30  and  32  communicate with the conduit body interior  22 .  
         [0024]     Referring particularly to  FIGS. 4-6 , a bushing  50  is shown in accordance with an embodiment of the present invention. Bushing  50  is an annular member having a first flared end  52 , an opposed second end  54  and a cylindrical body  56  therebetween. The bushing  50  is preferably formed in a molding process and is formed of a low friction material such as polytetrafluoroethylene (PTFE) such as Teflon®, or acetyl polymer such as Delrin®. While these materials are disclosed, other low friction materials, as well as various plastics, may also be employed.  
         [0025]     The bushing  50  is designed for accommodation within the connector body at the inner end  30   a ,  32   a . In that regard, each hub of conduit body  12  includes an annular rim  30   d ,  32   d  which is inwardly projecting into the opening of the hub, and an annular recess  30   e  and  32   e  which is recessed into the hub. The bushing  50  is designed for snap-fit engagement with the annular rim  30   d ,  32   d . When the bushing  50  is engaged, the first flared end  52  becomes disposed on a first surface of annular rim  30   d ,  32   d , an the opposed second end  54  becomes disposed on a second surface of the annular rim  30   d ,  32   d  and is further accommodated in recess  30   e ,  32   e . The opposed second end  54  of bushing  50  has an angled surface  54   a  to provide deflectable insertion of the bushing over the annular rim  30   d ,  32   d , which allows for snap-in accommodation of the bushing within the hub in this embodiment. The present invention therefore provides a bushing which may be applied to an existing conduit body so as to provide a friction resisting surface in a location where the conductor is being pulled through the conduit body.  
         [0026]     In an alternative embodiment of the present invention shown in  FIGS. 7 and 8 , a bushing  150  conforms to the shape of the conduit body opening by heat curling the bushing  150  to the conduit body. Although the bushing  150  is designed for accommodation within the conduit body at either inner end  30   a ,  32   a , only the inner end  30   a  is shown in  FIG. 8  for brevity and clarity.  
         [0027]     The bushing  150  in accordance with a preferred embodiment, is also an annular member but is formed in a three-step process. First, a bushing blank  150  as shown in  FIG. 7  is formed in a molding process of a plastic material. A variety of plastics may be used. The bushing blank  150  includes the first flared end  152  and an elongated cylindrical body  156 . Second, the cylindrical body  156  of the bushing blank  150  is then inserted from inside the conduit body  12  into the hub  30 ,  32 . Upon insertion the first flared end  152  should engage the surface of inner end  30   a ,  32   a , while a portion of the elongate cylindrical body  156  engages a first surface of the annular rim  30   d ,  32   d . Lastly, an end portion  154  of the cylindrical body  156  is heat curled into recess  30   e ,  32   e , forming the tapered second end  154  of bushing  150  for securing engagement with annular rim  30   d ,  32   d . This may be accomplished by introducing a heated mandrel from outside the conduit body  12  into hub  30 ,  32  to deform the plastic material and create a taper in the end portion  154  of the cylindrical body  156 .  
         [0028]     In all the preferred embodiments of the present invention, the bushing  50 ,  150  fully encircles and covers the annular rim  30   d ,  32   d  so that no portion thereof is exposed to a wire inserted therein.  
         [0029]     Furthermore, both the snap-fit and the heat curled arrangements described in the present invention allow the bushing  50 ,  150  to be completely rotatable on the annular rim. The ability of the bushing to freely rotate within the hub provides additional friction reduction which allows the wire to be pulled easily in either direction.  
         [0030]     Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be applied therein by one skilled in the art without departing from the scope or spirit of the invention.