Patent Publication Number: US-2006012175-A1

Title: Trunking and coupling means therefor

Description:
The present invention relates to trunking and coupling means therefor, and particularly, not exclusively, to waterproof trunking for carrying electrical cables.  
      The carrying of electrical cables in a network of trunking is used in many industries. In the food, beverage and pharmaceutical industries, where hygiene is of paramount importance, stainless steel trunking is regularly used. It is important that such trunking is easily cleaned and that places where dirt may gather, and infestation:may occur, are kept to a minimum.  
      In some situations it is necessary to provide a waterproof trunking. For example, where trunking is located near a high ceiling the preferred method of cleaning maybe to direct a jet of water at the trunking from the ground. As a result, the term waterproof is used within this document to refer to the amount of sealing of joints that is required, between parts of the trunking, in order to prevent water penetrating under the circumstances of this type of cleaning.  
      An example of a trunking system of this type is shown in  FIG. 1 . The trunking shown consists of elongated trunking members  10  and  12  having respective lids  14  and  16 . Each lid is retained in position by screws  18  and the junction between members  10  and  12  and respective lids  14  and  16  is sealed with a gasket (not shown). In order to provide an adequate seal for the waterproofing required it is necessary to provide a large number of screws  18 . If only a few screws  18  are used the lids  14  and  16  buckle along their edges, providing gaps which allow water inside the trunking members  10  and  12 . As a result of the large number of screws used to provide this seal, the time taken to install this waterproof trunking is significant.  
      A coupling  20  is used to join trunking members  10  and  12 . The coupling  20  consists of first coupling plate  22 , attached to trunking member  10  and a second coupling plate  24  attached to trunking member  12 . Between coupling plates  22  and  24  is a gasket seal  26 . The coupling plates  22  and  24  are fixed together using screws in holes  28 . This form of coupling creates a significant number of dirt traps around the edge of plates  22  and  24  and in holes  28 . The gasket  26  is also exposed around all of the edge of plates  22  and  24 , providing a further dirt trap.  
      Preferred embodiments of the present invention seek to overcome the above described disadvantages of the prior art.  
      According to an aspect of the present invention there is provided a section of waterproof trunking comprising:—
          at least one elongate tubular member of substantially rectangular cross-section having attaching means for attaching the or each said member to at least one further member and having at least one aperture in at least one respective side of said member for providing access to the interior of, said member, wherein the or each said aperture has a length less than the length of the or each said side measured in an axial direction along said tubular member and has a dimension less than the dimension of said side measured transverse to said axial direction; and     respective closure means for the or each said aperture.        

      By having a trunking member with small apertures in at least one side and closure means therefor, provides the advantage that the majority of any trunking member is entirely sealed along its length at all times. Therefore, the only points at which potential leaks may be found are around the closures to the aperture and the joints between adjacent members and any couplings therebetween. The advantage is also provided that the number of securing screws is significantly reduced, thereby reducing the time required to install the trunking as well as reducing the number of potential dirt traps which require cleaning.  
      In a preferred embodiment the attaching means includes at least one hole in said member adapted to receive a respective screw or bolt for retaining the member in position relative to a further member.  
      In another preferred embodiment the attaching means is at least one threaded member extending internally from said member and adapted to engage a coupling internally of said member, said coupling having slots therein allowing said threaded members to pass along said slots.  
      By providing the member with internally located threaded engaging means and slots in the coupling, the advantage is provided that the trunking member is provided with even fewer holes on its external surface thereby reducing the number of dirt traps.  
      The closure means may comprise a plate adapted to cover said aperture.  
      In a preferred embodiment said plate is provided with a plurality of holes adapted to receive respective screws or bolts therein for engaging with said member.  
      The closure means may further comprise a sealing gasket located between said plate and said member.  
      In a preferred embodiment the axial length of the aperture is less than 50% of the axial length of the member.  
      In another preferred embodiment the axial length of the aperture is less than 20% of the axial length of the member.  
      According to another aspect of the present invention there is provided a coupling for joining at least one first tubular waterproof trunking member of substantially rectangular cross section to at least one second tubular waterproof trunking member of substantially rectangular cross section, the coupling comprising:—
          a body adapted to extend within the or each first and second member;     retaining means for retaining said body and the or each said member together; and     at least one extension portion extending around said body and adapted to form a substantially continuous surface between a surface of said coupling and at least one surface of the or each first member and between a surface of said coupling and at least one surface of the or each second member.        

      By providing a coupling as described above, the advantage is provided that a tubular trunking, of the type described above, can be used, and can provide a waterproof seal between adjacent members. Providing a substantially smooth and continuous surface at the junction between the coupling and the member reduces the number of potential dirt traps.  
      In a preferred embodiment, edges of said body are shaped so as to provide a substantially smooth transition between an internal surface of the trunking member and a respective internal surface of the body.  
      In another preferred embodiment said edges are curved.  
      The retaining means may comprise a hole in said body adapted to align with a hole in a trunking member and adapted to receive a screw or bolt therein.  
      The hole may further comprise an internal thread.  
      In a preferred embodiment, said extension portion is provided with at sealing means for sealing between the trunking member and the extension portion.  
      The sealing means may comprise a gasket attached to said extension portion.  
      According to a further aspect of the present invention there is provided a coupling means for joining at least one first tubular waterproof trunking member having a rectangular cross section to at least one second tubular waterproof trunking member having a rectangular cross section, the coupling means comprising:—
          a body adapted to extend, within the or each first and second member;     retaining means for retaining said body and the or each said member together; and     sealing means extending around said body and adapted to provide a seal between the or each said first and second member.        

      By providing a sealing means extending around the body adapted to extend within first and second trunking members, the advantage is provided that a waterproof seal can be provided between adjacent members and the transition from one trunking member to the next can be provided in an almost continuous surface with a minimum number of dirt traps.  
      In a preferred embodiment edges of said body are shaped so as to provide a smooth transition between an internal surface of the trunking member and a respective internal surface of the body.  
      By providing such a smooth transition, the advantage is provided that as cables are pushed along a section of trunking and over a transition to a next section of trunking the coupling means provides little obstacle to that cable as it passes through.  
      In another preferred embodiment said edges are curved.  
      According to another aspect of the present invention there is provided a coupling for joining at least one first tubular waterproof trunking member of substantially rectangular cross section to at least one second tubular waterproof trunking member of substantially rectangular cross section, the coupling means comprising:—
          a tubular body, adapted to extend at least partially over the or each first member and at least partially over the or each second member;     retaining means for retaining said body and the or each said member together; and     sealing means for sealing a junction between the first and second members.        

      By providing a tubular coupling extending partially over the two trunking members being joined together, the advantage is provided that the junction between the first and second trunking members is completely covered, and completely sealed and a relatively smooth external surface having few dirt traps can be provided. The above coupling also has the advantage that the internal surface of the transition between the first and second trunking members is smooth thereby allowing free motion of the cables along the trunking members.  
      In a preferred embodiment at least one edge of at least one surface of said body is curved.  
      According to another aspect of the present invention there is provided a coupling for joining at least one first trunking member having a lid thereon to at least one second trunking member having a lid thereon, the coupling comprising:—
          a body, adapted to extend at least partially within the or each first and second member;     first retaining means for retaining said body and the or each said member together;     receiving portion adapted to receive all except one edge of surfaces at an end of said member and said respective lid;     clamping means adapted to be located over said edge of said member and lid not received in said receiving portion; and     second retaining means for retaining said clamping means and said retaining portion together.        

      By providing a coupling as described above the advantage is provided that the clamping means is able to assist in holding the lid of the trunking section in position. In particular, this is advantageous when a waterproof seal is required since the receiving portion can provide a waterproof seal between the adjacent trunking members and the clamping means provides a seal between the adjacent lids. The clamping means also maintains the sealing along the join between the member and the lid to the very end of the member and lid.  
      In a preferred embodiment the body consists of four surfaces.  
      By providing the body of the coupling with four surfaces, i.e. including an upper part adjacent the clamping means, the advantage is provided that a better seal between the adjacent lids is provided. However, where three surfaces are provided on said body easier access to the cables is provided once the clamping means has been removed.  
      According to another aspect of the present invention there is provided a trunking apparatus comprising:—
          at least one trunking section substantially as described above; and     at least one coupling substantially as described above.       

    
    
      Preferred embodiments of the present invention will now be described, by way of example only, and not in any limitative sense, with reference to the accompanying drawings in which:— 
       FIG. 1  is a perspective view of trunking members and a coupling of the prior art;  
       FIG. 2  is a perspective view of trunking sections of a first embodiment of the present invention;  
       FIG. 3  is a perspective view of a coupling and trunking members of a second embodiment of the present invention;  
       FIG. 4  is a perspective view of a coupling and trunking members of a third embodiment of the present invention;  
       FIG. 5  is a perspective view of a coupling and trunking members of a fourth embodiment of the present invention;  
       FIG. 6  is a perspective view of a coupling and trunking members of a fifth embodiment of the present invention;  
       FIG. 7  is a perspective view of a coupling and trunking members of a sixth embodiment of the present invention;  
       FIG. 8  is a perspective view of a coupling and trunking members of a seventh embodiment of the present invention;  
       FIG. 9  is a plan view of the coupling and trunking sections of FIGS.  7  or  8 ; and  
       FIG. 10  is a plan view of a coupling and trunking members of an eighth embodiment of the present invention. 
    
    
      Referring to  FIG. 2 , a section of waterproof trunking  30  has an elongate tubular member  32  of rectangular cross section, two opposing sides of which have holes  34  with screws therein. These holes act as means for attaching member  32  to further members  32   a  and/or  32   b . Member  32  also has an aperture  36  in one side. Aperture  36  has a length L 1  which is substantially less than the length L 2  of member  32 , this length being measured axially along member  32 . Aperture  36  also has dimension L 3  which is measured perpendicular to L 1  and L 2 , and this length is equal to or slightly less than length L 4 , the external dimension of member  32  measured in the same direction. Trunking section  30  also has closure means  38  for the or each aperture  36 . Closure means  38  has a cover plate  40  which is attached to member  32  by use of screws  42  through holes  43  and into threaded holes  44 . Plate  40  is also provided with a neoprene sealing gasket  46 .  
      In use, a trunking member  32  is attached to further trunking members  32   a  and  32   b  by use of an internal coupling means (not shown) and held in position the by screws in holes  34 . The person installing the trunking, and cabling therein, inserts his hand within aperture  36  and uses this aperture to access the cables inside. When installing a new cable, the cable is passed from one aperture to the next. Once all the cables are installed the closure means  38  are used to cover apertures  36 . Plate  40  is placed over aperture  36  and screws  42  are inserted through holes  43  into threaded holes  44 . Gasket  46  provides a waterproof seal to the trunking section.  
      An alternative coupling device might be external of the members  32 ,  32   a  and  32   b.    
      Referring to  FIG. 3 , a coupling  50  for joining a first tubular rectangular waterproof trunking member  32  to a second tubular rectangular waterproof trunking member  32   a  the coupling having a body  52 , which extends within the first and second members  32  and  32   a , and retaining means in the form of threaded holes  54 .  
      Holes  54  are adapted to receive screws  55 . Coupling  50  also has an extension portion  56  extending around the body  52 . Extension portion  56  is formed such that a surface  58  will, in use, form a substantially continuous surface with surface  60  of member  32  and surface  62  of member  32   a . Similarly surface  64  of extension portions  56  forms a substantially continuous surface with surface  66  of member  32  and surface  68  of member  32   a . Extension portion  56  is also provided with. neoprene gasket  70 .  
      In use, body  52  of coupling  50  is inserted within member  32 . Screws  55  are inserted through holes  34  and into threaded holes  54  and tightened so as to provide a strong mechanical joint. Because the coupling  50 , member  32  and screw  55  are all formed from stainless steel a good electrical contact is provided between all of these parts and as a result an earth continuity between trunking sections can be maintained. Similarly member  32  is inserted over body  52  such that holes  34  and  54  are aligned and screw  55  is inserted and tightened.  
      As an alternative, the extension portion  56  maybe entirely formed from a neoprene gasket. This would require that the extension portion be much narrower than that shown so that an almost continuous surface between the surfaces  60  and  66  of member  32 , and  62  and  68  of member  32   a  could be formed. Ideally the edges of and surfaces  60  and  62 , and  66  and  68  would be shaped so as to receive the gasket leaving as little neoprene exposed as possible. For example if these edges were given concave surfaces they would provide a suitable seal with a gasket of circular cross-section.  
      An alternative variation of this coupling is shown in  FIG. 4 . In this embodiment the retaining means, shown as holes  34  in  FIG. 3 , are replaced by slots  72  in body  52 . Members  32  and  32   a  are provided with threaded lugs internally of the members, which are not shown on  FIG. 4 .  
      In use, body  52  is slotted into members  32  and  32   a  such that the threaded lugs are located within slots  72 . A nut, also not shown, is then tightened over each threaded lug so as to provide a strong mechanical joint with good electrically conducting properties. Access to apply these nuts is gained through apertures  36 .  
      Referring to  FIG. 5 , a coupling  80  for joining a first tubular rectangular waterproof trunking member to a second tubular rectangular waterproof member has a tubular body  82  is adapted to extend partially over the first and second members  32  and  32   a . The coupling  80  also has retaining means, in the form of holes  84 , which are adapted to receive screws  86  which in turn engage with threaded holes  34 . Coupling  80  also has a neoprene sealing gasket  88 .  
      In use body  82  of coupling  80  is slid over the ends of members  32  and  32   a  and screws  86  are inserted through holes  84  and tightened in threaded holes  34 . As a result a mechanically strong and electrically continuous joint is provided.  
      An alternative variation of this coupling is shown in  FIG. 6 . In this embodiment the retaining means, shown as holes  34  in  FIG. 5  are replaced with slots  90 . The retaining means on body  82  of coupling  80  are four threaded lugs  92 , only one of which is shown in  FIG. 6 .  
      In use, body  82  of coupling  80  is slid over the ends of members  32  and  32   a . Threaded lugs  92  are located within slots  90  and a retaining nut, not shown, is tightened over each lug  92 . Neoprene seal  88  provides a waterproof contact between body  82  and members  32  and  32   a.    
      Referring to  FIGS. 7 and 9 , a coupling  100 , for joining a trunking section  102  with respective lid  104  and trunking section  106  with respective lid  108 , has a body  110 , adapted to be partially received within trunking sections  102  and  106 . Coupling  100  also has first retaining means, in the form of threaded holes  112 , which receive respective screws, not shown, inserted through holes  113  in trunking sections  102  and  106 . Coupling  100  also has receiving portion  114  which extends around three sides of body  110  and is adapted to receive edges of three respective sides of trunking sections  102  and  106  and lids  104  and  108 . Normally the inserted edges would be the edges of the trunking sections  102  and  106  and not the edge of lids  104  and  108 . For example the edges  116 ,  118  and  120  of trunking section  106  would be received within receiving portion  114  and edge  122  of lid  108  would not. Coupling  100  also has clamping means  124  and second retaining means  126 . Receiving portion  114  is provided with a neoprene gasket  128 .  
      In use coupling  100  is brought into engagement with trunking section  102  and two screws, not shown, are inserted through holes  113  and engage the threads in holes  112 . Similarly trunking section  106  is engaged with coupling  100  and two screws are similarly inserted. Cables are then laid in the trunking sections and through the body  110  of coupling  100 . This is made easier if the upper most surface of body  110  is not present. Lids  104  and  108  are then attached and screwed to trunking sections  102  and  106  and clamping means  124  is placed on top and fixed in position by second retaining means, screws  126 .  
      Referring to  FIG. 10  receiving portion  114  has rounded edges so as to provide a smooth transition between the surfaces of trunking sections  102  and  106  and the surface of receiving portion  114 .  
      An alternative variation of this coupling is shown in  FIG. 8 . In this embodiment the retaining means, shown as holes  112  in  FIG. 7  are replaced with slots  130  which are adapted to receive threaded lugs  132  and are fixed in position using threaded nuts, not shown.  
      It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.