Abstract:
An improved duct or raceway including a modular duct system and manufacturing technique for fabricating the components of the improved system as used in connection with electrical control panel wiring. The duct system utilizes an interlocking construction that may comprise extruded plastic base and top members connected to interlocking apertured sidewalls. The sidewall members, when fabricated by injection molding techniques provide for smooth surfaces for accepting protruding wires or relatively small wire bundles.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to wiring duct assemblies, and in particular to a modular duct assembly or raceway permitting expansion of components as needed to provide electrical wiring protection.  
           [0002]    Past duct assemblies have presented numerous problems; especially where it is desired to expand a system once it has been installed. It often becomes necessary to provide additional raceway or duct components. Efforts to expand an already installed system involve the difficulties and expense of dismantling and reassembling various constituent components.  
           [0003]    To overcome problems concerned with both the manufacture and installation of components used in a raceway wiring system, various wiring duct system embodiments have been provided. Such systems generally have utilized a main conduit section defining a main passage for wires, the wires generally being bundled together by means of longitudinally spaced wire ties, or encased in an insulating sheath. This main section was secured to a mounting surface.  
           [0004]    In order to add additional passages for wires, one or more sidewall sections were added to the main section. The sidewall sections were apertured to provide various configured openings or slots to accommodate selected wires selected from a main raceway bundle. The wires emerging from the sidewall apertures were bent to follow exterior paths through other raceway systems, or to be directly connected an electrical device. The sidewalls have also been made without apertures, when no openings were necessary, nor desired.  
           [0005]    Installers of wiring ducts often utilized a main section of relatively extended length enclosed by relatively short length sidewalls or covers. These sidewalls were preferably of various lengths and of desired aperture configurations. In these circumstances, it would be desirable to have the option of using interchangeable shorter sidewall lengths, which would be readily and facilely positioned along the main duct length during assembly and even substituted later without requiring major dismantling of the assembly.  
           [0006]    Further, prior manufacturing techniques included die cut openings and edges creating relatively rough, and often undesirable sharp edges around the perimeter of the openings, making it difficult to install the needed wiring. The sharp edged perimeters also have been known to cut and remove wire insulation, particularly when the insulation has been applied as a thin coating to small diameter wires.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention overcomes the shortcomings of conventional duct products by providing interchangeable sidewalls of various configurations and lengths. The variety of interchangeable components allows for more compact packaging for shipping and inventory, resulting in lower shipping cost and less inventory space. The modular design also provides a much lower inventory cost due to fewer components required to make greater combinations of styles and sizes. Further, the invention contemplates an improved fabricating technique that avoids the sharp edges associated with prior production techniques.  
           [0008]    It is a further object of this invention to provide a higher performing, higher quality product in an efficient manner. Devices made in accordance with this invention have particular application for networking, routing and protecting wire and cable in cable and wire management applications and installations.  
           [0009]    The improved duct or raceway of this invention contemplates a modular duct system and manufacturing technique for fabricating the components of the improved system as used in connection with electrical control panel wiring. The duct system preferably embodies an interlocking construction that may comprise extruded plastic base and top members connected to interlocking apertured sidewalls. The sidewall members, when fabricated by injection molding techniques provide for smooth surfaces for accepting protruding wires or relatively small wire bundles. Sidewalls may be extruded and punched, however when this technique is used the resulting edges are mechanically chamfered to provide for smooth surfaces.  
           [0010]    The base member is preferably provided with a pair of coextensive, laterally spaced, upstanding curbs. Each of the curbs includes a coextensive trough arranged to releasably receive a sidewall member. Additionally, the curb troughs each are preferably configured to receive a sidewall member by a snap-action grip. The grip is provided by means of a detent-indent arranged along the longitudinal lengths of the mating base and sidewall. Subsequent removal of a sidewall may be accomplished by sliding out through a base end or by prying upward in an indent well with a screw driver or other prying devices. The sidewalls may be apertured to provided any of several peripheral openings or slotted configurations arranged to receive segregated wires or relatively smaller wire bundles bent away from a main bundle lying in the longitudinal track defined by the laterally spaced curbs. Alternatively, the sidewall member may also be devoid of openings to provide a solid barrier and enclose the duct, or wireway. The top member is preferably provided with means to permit slideable engagement with the sidewalls. This engagement means may optionally include a bead of caulk or adhesive disposed in the engagement means to provide additional frictional engagement and assure proper fit between engaging members.  
           [0011]    Initial assembly of the present invention is simplified over past duct systems. The bas member may be mounted to a control panel or other surface independently of the sidewalls. Sidewalls may then be added as needed as the total assembly is built. If additional width is required, the present invention provides further flexibility in application. In this case two base members may be assembled side by side. Use of three sidewalls provides for two outer sidewalls and an inner divider. In that case a central divider may be snap fit. Base members of varying widths are also within the scope of this disclosure. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a perspective view of one embodiment of the invention, and illustrating a modular duct assembly including a cooperating top member, oppositely disposed, apertured sidewalls and a base member.  
         [0013]    [0013]FIG. 2 is a cross sectional view taken along lines  2 - 2  of FIG. 1.  
         [0014]    [0014]FIG. 2 a  is a fragmentary view of FIG. 2 and illustrates a means for facilitating removal of sidewall from the base by means of insertion of a wedge, such as a screwdriver tip at the juncture of the lower portion of the sidewall and a flexible curb outer wall extending upwardly from the base member.  
         [0015]    [0015]FIGS. 3 and 4 are fragmentary cross sectional representations taken approximately along lines  2 - 2  of FIG. 1 and illustrating a modified base member with two versions of a separating partition or divider arrangement, suitable for selected installations of the assembly of this invention.  
         [0016]    [0016]FIG. 5 is a fragmentary plan view of a molded apertured sidewall member, and particularly illustrating circular apertures with smooth edge surfaces for receiving wires or wire bundles.  
         [0017]    [0017]FIG. 6 is a fragmentary plan view of a molded sidewall member including longitudinally spaced, upstanding fingers defining slots with smooth edges for receiving wires or bundles of wires.  
         [0018]    [0018]FIG. 7 is a perspective view illustrating a modular duct assembly according to the present invention and used to retain a bundle of wires divided into two portions, one portion arranged to protrude through a slotted sidewall member and the other portion arranged to protrude through a sidewall member with circular apertures. 
     
    
     DETAILED DESCRIPTION  
       [0019]    Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.  
         [0020]    Referring to FIGS. 1 and 2, a preferred embodiment of the modular duct assembly  10  includes a base member  20 , a top member  30 , an apertured sidewall member  40   a  with circular openings  44  and a slotted sidewall member  40   b . Slotted sidewall member  40   b  include adjacent fingers  45  that define a plurality of slotted apertures  4   b . The members  20 , insert space  30  and  40   a  and  40   b  are preferably made as independent components, with the members  40   a  and  40   b  being interchangeable. The sidewall members  40   a  and  40   b  are slidably secured to the base and top members  20  and  30 , respectively. As shown in FIG. 2, sidewall member  40   b  preferably includes a frangible area  35  defined by longitudinal scoring or grooving  36 . An enclosing, imperforate sidewall member (not shown) may also be substituted for the sidewall members  40   a ,  40   b  where access to protruding wires is not required. Further, as will be later explained, the sidewall members  40   a ,  40   b  are preferably configured to be independently removed and inserted from the bottom and top members  20  and  30 , respectively, without disturbing previously assembled components. This arrangement is especially advantageous where the sidewall members  40   a ,  40   b  are shorter than the length of the base and top members  20  and  30 . The shorter sidewall members  40   a ,  40   b  may be removed and replaced without disturbing adjacent sidewall sections or members by slip fitting or snapping into the base member  20 . The top member  30  slides over the oppositely disposed sidewall members  40   a  and  40   b.    
         [0021]    Further, with respect to the fragmentary view of FIG. 2 a , it will be observed that removal of the sidewall member  40   b  may be facilitated by wedging insertion of a conventional flat screwdriver tip  29  between the upper edge of the outer barb wall  23  and the abutting curved portion  40   c  to release the sidewall  40   b  from the groove  25 .  
         [0022]    The views of FIGS. 1 and 2 illustrate each of the component assembly members in their assembled relationship. The assembly shown includes the base member  20  with integrally formed, oppositely disposed, upstanding curbs  21 . The curbs  21  preferably extend for the entire length of the base member  20  and each contain a generally U-shaped coextensive groove  22 . Each of the curb grooves  22  are further defined by a pair of bifurcated outer and inner walls  23  and  24 . The outer wall  23  also includes a coextensive, inwardly facing, indent or groove  25 . The base member  20  may be extruded or injection molded of a relatively resilient material to provide a snap fit with a detent, or tongue  41  coextensive with a respective downwardly extending sidewall base portion  42 . The base portion  42  of a respective sidewall member  40   a ,  40   b  may be releasably and slidably received by the groove  22  of a selected upstanding base member curb  21 . The outer and inner walls  23  and  24  of the base member  20  are each provided with continuous bottom grooves  26  and  27 , respectively. The grooves  26  and  27  provide flexibility to the walls  23  and  24  for ease in snap fitting the sidewall members  40   a ,  40   b  to the curbs  21  of the base member  20 . The floor  28  of base member  20  may be further supplied with apertures  34  to allow mounting means (not shown) to pass therethrough.  
         [0023]    Again referring to the view of FIG. 2, it will be observed that the top member  30 , which may be formed as an extrusion, includes means for completing the assembly by a snap action fitting with respect to the top surfaces  43  of the sidewall members  40   a  and  40   b . Preferably, the top member  30  is supplied with a pair of overhanging curbs  31 . The curbs  31  each have a longitudinally extending overhanging flange  32  defining an undercut, coextensive groove  33 . The grooves  33  each engage with a laterally extending elongated tongue  47  coextensive with the length of the top member  30 . Since the sidewall members  40   a ,  40   b  are formed of plastic material, and extend upwardly away from the base member  20 , the tongue  47  will be biased outwardly to slidably engage the groove  33 . Selecting the width of the top member  30  to be slightly less than the width of the base member  20  may increase the relative tightness between the tongue  47  and the groove  33 .  
         [0024]    Referring next to the fragmentary views of FIGS. 3 and 4, the present invention may also provide divider means, when such is desired. As illustrated in FIG. 3, an upstanding separator or partition  50   a  may be slidably received between upstanding, inwardly curved, spaced apart, supporting members  29   a  and  29   b . The members  29   a  and  29   b  are each preferably molded integrally with the floor  28  of the base member  20 . The removable partition  50   a  is preferably extruded to a desired length, which is usually selected to be coextensive with the length of the base member  20 , and may be of the same or lesser height than the sidewall members  40   a ,  40   b . The partition  50   a  preferably includes a coextensive sub-base  51 . The sub-base  51  is retained by a sliding fit in the groove formed between the facing support members  29   a  and  29   b  of this version of the base member  20 .  
         [0025]    Another version of the partitioning or dividing means is illustrated in the view of FIG. 4. Here, the divider, or partition,  50   b  includes a supporting base  52  providing a coextensive groove  53 . The groove  53  is configured to provide inturned, shouldered flanges  54  that grasp the head  55  of a fastener  56 .  
         [0026]    With reference to FIG. 1, it will be observed that the selected sidewall member  40   a  is provided with a plurality of spaced-apart, circular apertures  44 . As mentioned above, sidewall  40   a  may be used on either side of the duct  10 , when required. It will also be observed that each of the apertures  44  has a relatively smooth perimeter. The smooth perimeter, or edging,  44   a  (See FIG. 5) is achieved when the sidewall member  40   a  is formed by injection molding. Prior devices have generally been fabricated from extrusions that are die punched after extruding. Such machining operation provides relatively sharp perimeters, which can scrape off insulation from wires fed through the apertures  44  (See FIG. 7). This is especially true when relatively thin insulation is applied to small diameter wires used in communication installations. It will be apparent that where smooth surfaces are not required or desired the sidewall members  40   a ,  40   b  may be extruded and punched with mechanically formed chamfered edges without departing from other aspects of the invention.  
         [0027]    With respect to FIGS. 1 and 6, it will be observed that the sidewall member  40   b  is comprised of longitudinally spaced, upstanding fingers  45  projecting from the base portion  42  of the sidewall member  40   b  seated in the groove  25  of the base member  20 . The adjacent fingers  45  define a plurality of slotted apertures  46 . As in the case of the circular apertured sidewall member  40   a , the sidewall member  40   b  is preferably injection molded to fabricate the fingers  45  with smooth edges  45   a , as shown with particularity in the view of FIG. 6. At least one finger  45  preferably includes a frangible area  35  defining a longitudinal score or groove  36  at the base of individual fingers  45 . This permits the individual finger or fingers  45  to be broken and removed to provide a wider slotted aperture  46  to accept a larger wire or bundled cable  60  passing therethrough. (See FIG. 7) Thus wires  61  passing through the slotted apertures  46  may do so without fear of scratching or removal of insulation. Laterally projecting ears  48  are provided intermediate the top and bottom portions of the fingers  45  to separate upper and lower portions  46   a  and  46   b  of the slotted apertures  46 . The ears  48  provide a means of partitioning the slotted area for segregation of wires  61  or small wire or cable bundles  60 , and thereby minimize entanglement of the wires during installation and removal of the wires or bundles from the slotted apertures  46 .  
         [0028]    With reference to FIG. 7, it will be observed that the modular duct assembly  10  finds use as a wiring device for transporting, supporting and distributing cable or wire bundles  60  or individual wires  61 . As mentioned earlier, individual fingers  45  may be broken off to provide a wider slotted aperture  46  to accept bundled cable  60  therethrough.  
         [0029]    The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.