Abstract:
A cable duct coupler for coupling a first cable duct section to a second cable duct section without the need for tools, the cable duct coupler comprising a channel portion, a first outer guide element and a second outer guide element, a barb mount extending from at least one of the channel portion and the outer guide elements, and a barb having a body and first and second arms extending from the body, the barb being mounted on the barb mount, wherein at least a portion of the first arm extends at an angle between the first portion of the channel portion and the barb body and at least a portion of the second arm extends at an angle between the second portion of the channel portion and the barb body.

Description:
RELATED APPLICATION 
   This application is a continuation, claiming priority to previously filed U.S. patent application Ser. No. 10/323,527, filed on Dec. 18, 2002, now U.S. Pat. No. 6,634,605, which is a continuation, claiming priority to previously filed U.S. patent application Ser. No. 10/039,325, filed on Oct. 27, 2001, now U.S. Pat. No. 6,523,791, which is a continuation-in-part application, claiming priority to previously filed U.S. patent application Ser. No. 09/585,699, filed on Jun. 1, 2000, now U.S. Pat. No. 6,450,458, the entirety of the previously filed applications being incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   Field of the Invention 
   Raceway duct systems have become very popular in recent years to route, protect, and conceal data, voice, video, fiber optic and/or power cabling. Such systems allow custom installation and can be provided within walls or more preferably provided on external surfaces, allowing ready access for reconfiguration, repair, or installation of additional equipment. Such systems may typically include various sections of duct or raceway, including straight sections and various fittings, such as 90° elbow fittings, 45° elbow fittings, T-fittings, four-way intersection (x) fittings, and the like, respective ones of which are affixed together by duct couplers to cumulatively form a duct system. 
   Due to the increase in number and sophistication of such raceway duct systems, the number of duct couplers being installed in such systems has also increased significantly. Therefore, it is important to have couplers that are easy to install and expensive to manufacture, and that provide relatively high pull-out force to prevent unintended disassembly. 
   SUMMARY OF THE INVENTION 
   In one form of the invention, there is provided a cable duct coupler for coupling a first cable duct section to a second cable duct section without the need for tools, the first and second cable duct sections each having an end, the cable duct coupler comprising a channel portion having a first portion generally complementary to the end of the first cable duct section and a second portion generally complementary to the end of the second cable duct section, a first outer guide element generally complementary to the end of the first cable duct section and a second outer guide element generally complementary to the end of the second cable duct section, wherein the end of the first cable duct section is receivable into the coupler between the first portion of the channel portion and the first outer guide element and the end of the second cable duct section is receivable into the coupler between the second portion of the channel portion and the second outer guide element, a barb mount extending from at least one of the channel portion and the outer guide elements, and a barb having a body and first and second arms extending from the body, the barb being mounted on the barb mount, wherein at least a portion of the first arm extends at an angle between the first portion of the channel portion and the barb body and at least a portion of the second arm extends at an angle between the second portion of the channel portion and the barb body, wherein upon insertion of the end of the first cable duct section into the coupler between the first portion of the channel portion and the first outer guide element, the first arm of the barb engages the first cable duct section to significantly resist withdrawal of the first cable duct section, and wherein upon insertion of the end of the second cable duct section into the coupler between the second portion of the channel portion and the second outer guide element, the second arm of the barb engages the second cable duct section to significantly resist withdrawal of the second cable duct section. 
   In another form of the invention, there is provided a cable duct system comprising a first cable duct section having an end, a second cable duct section having an end, and a cable duct coupler including, a channel portion having a first portion generally complementary to the end of the first cable duct section and a second portion generally complementary to the end of the second cable duct section, a first outer guide element generally complementary to the end of the first cable duct section and a second outer guide element generally complementary to the end of the second cable duct section, wherein the end of the first cable duct section is receivable into the coupler between the first portion of the channel portion and the first outer guide element and the end of the second cable duct section is receivable into the coupler between the second portion of the channel portion and the second outer guide element, a barb mount extending from at least one of the channel portion and the outer guide elements, and a barb having a body and first and second arms extending from the body, the barb being mounted on the barb mount, wherein at least a portion of the first arm extends at an angle between the first portion of the channel portion and the barb body and at least a portion of the second arm extends at an angle between the second portion of the channel portion and the barb body, wherein upon insertion of the end of the first cable duct section into the coupler between the first portion of the channel portion and the first outer guide element, the first arm of the barb engages the first cable duct section to significantly resist withdrawal of the first cable duct section, and wherein upon insertion of the end of the second cable duct section into the coupler between the second portion of the channel portion and the second outer guide element, the second arm of the barb engages the second cable duct section to significantly resist withdrawal of the second cable duct section. 
   In yet another embodiment of the invention, there is provided a method for assembling a cable duct system, the method comprising providing a first cable duct section having an end, providing a second cable duct section having an end, providing a cable duct coupler having a channel portion with a first portion generally complementary to the end of the first cable duct section and a second portion generally complementary to the end of the second cable duct section, a first outer guide element generally complementary to the end of the first cable duct section and a second outer guide element generally complementary to the end of the second cable duct section, a barb mount extending from at least one of the channel portion and the outer guide elements, and a barb having a body and first and second arms extending from the body, the barb being mounted on the barb mount, wherein at least a portion of the first arm extends at an angle between the first portion of the channel portion and the barb body and at least a portion of the second arm extends at an angle between the second portion of the channel portion and the barb body, inserting the end of the first cable duct section between the first portion of the channel portion and the first outer guide element until the first arm of the barb engages the first cable duct section to significantly resist withdrawal of the first cable duct section, and inserting the end of the second cable duct section between the second portion of the channel portion and the second outer guide element until the second arm of the barb engages the second cable duct section to significantly resist withdrawal of the second cable duct section. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a cable duct coupler and cable duct system in accordance with an embodiment of the invention wherein first and second cable duct sections are coupled together by the coupler; 
       FIG. 2  is a perspective view of the coupler of  FIG. 1 ; 
       FIG. 3  is a front elevational view of the coupler of  FIG. 1 ; 
       FIG. 4  is a partially exploded perspective view of the duct section coupler of  FIG. 1  showing the alignment of an end of the cable duct section with the coupler and the alignment of the barb, cover, and screw to the coupler body; 
       FIG. 5  is a cross-sectional view of the coupler of  FIG. 1  showing the barb thereof in detail, the cross-sectional view taken across the line  5 - 5  in  FIG. 1 ; 
       FIG. 6  is a perspective view of an alternative embodiment of the barb; 
       FIG. 7  is a reverse perspective view of the barb of  FIG. 6 ; and 
       FIGS. 8-15  show various cable duct system fittings, with lids, that may be coupled to each other or to a cable duct section by a coupler in accordance with the invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1  shows a cable duct system  10  in accordance with an embodiment of the invention, and in particular shows a pair of discrete cable duct sections  12  each having an end  13  ( FIG. 4 ) inserted into and retained by a cable duct coupler  20  in accordance with an embodiment of the invention. As seen, the end of the cable duct section preferably has a U-shape, with a bottom portion  14  and two upwardly extending side portions  16 . The bottom portion may preferably include axially extending ribs  18  for strengthening the cable duct section, for facilitating the mounting of the cable duct section onto a floor, wall, bracket, or other supportive structure, and for preferably providing alignment criteria relative to the coupler  20 . At or near the distal ends of the side portions  16 , there may also preferably be a curved lip  19  or the like for facilitating the attachment of a lid over the cable duct section  12  to substantially enclose the cable duct section and retain one or more cables therein, as is well known in the art. The duct section may also include longitudinal ribs  17  on the outside thereof. The cable duct section is preferably made from a hard plastic or other strong, slightly deformable, dielectric material. 
   The coupler  20  is shown in greater detail in  FIGS. 2 and 3 , with  FIG. 2  showing the coupler in perspective and  FIG. 3  showing a front elevational view thereof. The coupler  20 , as seen previously in  FIG. 1 , joins two discrete cable duct sections  12 , and the coupler has an axial direction generally in accordance with and parallel to the direction in which cables will generally lie as they pass through the coupler, i.e., generally in line with the longitudinal direction of the cable duct sections. 
   Coupler  20  has a channel portion  22  which defines the cable pathway therethrough as the cable makes its way from one cable duct section to another. In a preferred embodiment, the channel portion includes a bottom portion  30  and two side portions  32  extending somewhat perpendicularly to each end of the bottom portion  30 . The side portions  32 , in a preferred embodiment, form a slightly obtuse angle (&gt;90°) relative to the bottom portion  30 , to open the section and facilitate cable retention and withdrawal. The channel portion  22  has an inner surface  26  including the facing surfaces of the side portions  32  and the upper surface of the bottom portion  30 , and an outer surface  27  including the opposite surfaces of the bottom and side portions  30  and  32 . 
   In a preferred embodiment, the coupler includes a rib  36  extending outwardly and generally perpendicularly from the outer surface  27  of the channel portion  22 . The rib  36  preferably completely traverses the outer surface  27  of the channel portion  22 , dividing it and the entire coupler into two symmetric halves, a first portion  24  for receiving a first cable duct section and a second portion  25  for receiving a second cable duct section. In a preferred embodiment, the rib  36  is centrally disposed along a line of symmetry for the coupler. As seen in  FIGS. 2 and 3 , the outer surface  27  of the channel portion  22  may preferably include contact ridges  28  for contacting and facilitating the alignment of an end of a cable duct section when inserted into the coupler. 
   Coupler  20  also includes a number of outer guide elements facilitating the alignment of a duct section end as it is inserted into the coupler. In the illustrated embodiment, the coupler includes a pair of outer guide elements  40  disposed opposite the outer surface  27  of the bottom portion  30  of the channel portion  22 , and a pair of outer guide elements  42  opposing the outer surface  27  of each side portion  32  of the channel portion  22 . The outer guide elements  40  include guide surfaces  44  and axial web portions  48 , with the guide surfaces  44  and axial web portions  48  being supported by a centered transverse web portion  50 , all of which extend from the narrow central rib  36  traversing the outer surface  27  of the channel portion  22 . The outer guide elements  42  opposite the side portions  32  of the channel portion also include guide surfaces  44  and axial web portions  48 , but they are supported by a pair of non-centrally disposed transverse web portions  52  extending outwardly from the corresponding guide surfaces  44 . Any or all of the guide surfaces  44  of the respective outer guide elements  40  and  42  may preferably include alignment ridges  46  for contacting and facilitating the alignment of an end of a cable duct section being inserted into the coupler. Additionally, there may be any number of guide elements  40  and  42  within the scope of the invention, and the gaps  49  between adjacent guide elements may, in particular embodiments of the invention, be spanned by a strengthening web  53  to strengthen the coupler generally. 
   In the illustrated embodiment of the invention, and as best seen in  FIGS. 2 and 4 , between particular outer guide elements,  40  and  42 , there are gaps  49 . Preferably disposed between transverse web portions  50  and  52  corresponding to adjacent outer guide elements  40  and  42 , and preferably disposed on or substantially on the central rib  36 , there is a barb mount  60  for receiving a fastener therein. In the illustrated embodiment, the barb mount supports a barb  54  thereon and has an internally threaded aperture  78  therein. As seen in  FIGS. 4 and 5 , the barb  54  includes a pair of arms  64  bent back relative to a body portion  62  at an angle greater than 90 degree so that the arms angle towards each other. The barb body  62  is mountable upon the barb mount  60  and retainable thereon by an externally threaded screw  58  or other fastener which penetrates a hole  56  in the barb and is directed into the internally threaded screw aperture  78  in the barb mount  60 . Externally threaded screw  58  or other fastener may also serve as a release mechanism adapted to release barbs  54  from retaining a first cable duct section positioned within a first duct-receiving portion of coupler  20 . Thus, the barbs  54  are mounted in gaps  49  between particular outer guide elements  40  and  42 . In a preferred embodiment of the invention, the barb may have serrated edges  66  at the distal ends of its arms  64 . The serrated edges permit the barb arms to more reliably engage inserted cable duct sections so as to resist withdrawal of the section from the coupler. In particular, the serrated edge may “bite” or “dig” into the material of the duct section  12 , such as extruded plastic. 
   Also in a preferred embodiment of the invention, and as best seen in  FIGS. 6 and 7 , the barb body  62  may have one or more flanges  68  running lengthwise along the edges thereof. Such flanges render the barb body  62  less prone to bending/deflection during withdrawal of a duct section from the coupler and thereby increase the minimum withdrawal force of the coupler. Also in a preferred embodiment of the invention, portions of the barb arms  64  and portions of the barb body  62  include one or more ribs  70  to strengthen the barb and make it less vulnerable to having the barb arm  64  deflected relative to the barb body  62 , especially during duct section withdrawal. Also in a preferred embodiment of the invention, the barb cover  72  may include a hole centrally located therein so that it may be retained over the barb body by the screw  58 . Covers  72  enhances the aesthetic appearance of the coupler by hiding the metal barbs  54  and, in some embodiments, may provide contact support for the barbs  54  when withdrawal force is applied to a cable duct section inserted into the coupler. 
   When the end  13  of a cable duct section  12  is to be inserted into a coupler  20  in the illustrated embodiment of the invention, the U-shaped profile of the end  13  is inserted to generally circumscribe the outer surface  27  of the channel portion  22  of the coupler. The various guide surfaces  44  of the outer guide elements  40  and  42  may initially contact the end  13  of the cable duct section  12  and facilitate alignment of the cable duct section into the coupler. In particular, contact ridges  46  of the guide surfaces  44  assist in the alignment upon insertion, as do the contact ridges  28  on the outer surface  27  of the channel portion  22 . The cable duct section&#39;s strengthening ribs  18  are aligned to fit into gaps between the outer guide elements  40 ,  42 . 
   While the end  13  of the cable duct section  12  approaches its fully inserted position adjacent to the central rib  36 , it encounters barb arms  64  angled generally in the direction of the insertion. Because the end  13  lacks sufficient clearance, it will contact one of each barb&#39;s arms  64  upon insertion. The barb arms  64  will deflect slightly toward their respective barb bodies  62  to permit the end  13  to pass thereunder without offering substantial resistance as the end continues toward the central rib  36 . The serrated edges  66  of the barb arms  64  will not significantly bite into the extruded plastic end  13  during insertion due to the angle of the barb arms  64 . Once the end  13  comes flush with the central rib  36 , the insertion is completed. 
   When a withdrawal force is applied to the cable duct section  12 , the end  13  of the cable duct section begins to and nominally slides away from the central rib  36 , but upon such nominal movement in the withdrawal direction, the serrated edges  66  of the barb arms  64  bitingly engage and dig in to the extruded plastic of the duct section  12 . Longitudinal ribs  17  on the exterior of the duct section are optionally provided to enhance the magnitude of engagement of the barb arms  64  therewith. The withdrawal forces are thereby countered by the resistance of the barb arms  64  to open. Thus, in order to withdraw the cable duct section, enough withdrawal force must be applied to either significantly deform the arms of the barbs or to permit the serrated edges  66  of the barb arms  64  to lose their biting grip thereon and thereby score the cable duct section  12  as it is withdrawn from the coupler. In a preferred embodiment of the invention, the duct section slides under the barb arm, with possible socring, and the barb arms are not permanently deformed when a withdrawal force exceeding the minimum withdrawal force is applied to the duct section. Avoiding damage to the barb arms permits the coupler to be reused. 
   In the embodiments of the invention including a barb cover, such as barb cover  72 , the cover may prevent or limit deflection of the barb body in a direction away from the cable duct section so as to support the magnitude of biting engagement between the serrated edge  66  and the extruded duct section. In the embodiments shown in  FIGS. 6 and 7 , the flange(s)  68  and the rib(s)  70  provide the support without the presence of a barb cover. 
     FIGS. 8-15  show various cable duct system fittings, with lids, that may be coupled to each other or to a straight cable duct section by a coupler in accordance with the invention.  FIG. 8  shows an outside vertical right angle fitting for routing cable between a horizontal orientation and a vertical orientation.  FIG. 9 , similarly, shows an outside vertical 45° fitting.  FIG. 10  shows an inside vertical 45° fitting.  FIG. 11  shows an inside vertical right angle fitting.  FIG. 12  shows a four-way cross fitting.  FIG. 13  shows an inside vertical right angle fitting.  FIG. 14  shows a horizontal Tee fitting.  FIG. 15  shows a vertical Tee fitting. These fittings are exemplary and in no way limit the scope of the application of the inventive cable duct system and coupler. 
   The disclosed invention provides an improved cable duct coupler and cable duct system. It should be noted that the above-described and illustrated embodiments and preferred embodiments of the invention are not an exhaustive listing of the forms such a coupler and system in accordance with the invention might take; rather, they serve as exemplary and illustrative of embodiments of the invention as presently understood. By way of example, and without limitation, a non-U-shaped coupler and correspondingly shaped duct sections are contemplated to be within the scope of the invention. Similarly, while the illustrated embodiment includes covers over each of the barbs in the coupler, embodiments having no covers are also contemplated by the invention. Many other forms of the invention are believed to exist. The invention is defined by the following claims.