Abstract:
Electrical wiring trunking with a flexible hinge is reinforced to prevent impacts causing accidental opening of the cover section. The base section and the cover section are attached laterally by a hinge in the form of a flexible strip and respectively comprise a groove and a rib in the vicinity of the hinge and establishing a stiffening structure around the flexible strip when the cover section is closed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to electrical wiring trunking with a flexible hinge, mainly comprising two sections, namely a base section which usually has a U-shaped profile and a cover section shaped to be forcibly nested with the base section; it relates more particularly to an improvement relating to a flexible longitudinal hinge connecting the cover section to a lateral wall of the base section. 
     2. Description of the Prior Art 
     U.S. Pat. No. 5,235,136 describes wiring trunking of the above kind in which the hinge is formed by thinning the material extending longitudinally on one side between the part forming the base section and the part forming the cover section. 
     The longitudinal edges of the base section and the cover section opposite the hinge have forcible nesting means exploiting the relative flexibility of the material, which is generally a semirigid plastics material. The hinge area is relatively deformable, however, and the closed trunking may accidentally open due to a frontal impact on the cover section or a lateral impact on the wall of the base section that incorporates the hinge. 
     To remedy this drawback, the above prior art document provides a reinforcement inside the base section consisting of a longitudinal flange adjoining the wall of the base section that incorporates the hinge. This complicates extruding the sections constituting the trunking and limits the space available for wiring within the trunking. The invention overcomes these drawbacks. 
     SUMMARY OF THE INVENTION 
     To be more precise, the invention concerns electrical wiring trunking including a base section, preferably with a globally U-shaped profile, a cover section shaped to forcibly nest with the base section and attached laterally to the base section by a longitudinal hinge defined by a flexible and relatively deformable strip, and a rib member and a groove member in the vicinity of the hinge and on respective opposite sides of the longitudinal direction of the strip, wherein one of said members is on the base section, the other of said members is on the cover section, and the rib member engages in the groove member when the cover section is closed to establish a stiffener structure around the flexible strip. 
     The rib member and the groove member can advantageously be shaped to provide a stable open or at least partly open position of the cover section relative to the base section. This stable position is assured by contact or a buttress effect between an edge of the rib member and an edge of the groove member, for example, operative for a given position of the cover section and which can be forcibly overcome to close the trunking completely, exploiting the relative flexibility of the hinge. 
     The hinge can be coextruded with the cover section and the base section. It is made from a different and more flexible material, for example, or even a slightly elastic material, for example using the coextrusion process well known in the art. 
     In a simpler embodiment, which is currently a preferred embodiment, the hinge can consist of an attached adhesive tape. 
     The invention will be more clearly understood and other advantages of the invention will become more clearly apparent from the following description of various embodiments of electrical wiring trunking in accordance with the invention given by way of example only and with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view in cross section of a first embodiment of wiring trunking with the cover section open. 
     FIG. 2 is a view analogous to FIG. 1 with the cover section partly open in a stable position. 
     FIG. 3 is a view analogous to FIG. 1 with the cover section closed. 
     FIG. 4 is a view in cross section of a second embodiment of the invention with the cover section partly open. 
     FIG. 5 is a view analogous to FIG. 4 with the cover section closed. 
     FIG. 6 is a view in cross section of a third embodiment of wiring trunking in accordance with the invention with the cover section partly open. 
     FIG. 7 is a view analogous to FIG. 6 with the cover section closed. 
     FIG. 8 is a view similar to FIG. 7 of a variant of the trunking of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more particularly to FIGS. 1 to  3 , electrical wiring trunking  11  mainly comprises a base section  12  with a globally U-shaped profile, a cover section  13  and a longitudinal hinge  15  defined by a flexible and relatively deformable strip  16  between the base section and the cover section. The three members are shown in cross section; they are extruded sections and consequently have a constant cross section. The description of the trunking in cross section is therefore sufficient to characterize it. Here the cover section  13  is globally U-shaped in cross section; it is shaped to nest forcibly with the base section  12 . 
     To be more precise, the base section comprises a plane wall  18  in the form of a strip forming the base of the trunking and extended by two lateral walls  19 ,  20  which extend longitudinally and are globally perpendicular to the wall  18 . The lateral wall  20  is attached to the cover section  13  by the hinge  15  and the opposite lateral wall  19  incorporates a groove  21  opening longitudinally onto its outside face. 
     The cover section  13  further includes a flat strip  22  extended by two longitudinal lateral walls  23 ,  24  which are globally perpendicular to the strip  22  and respectively cooperate with the lateral walls  19 ,  20  of the base section. The lateral wall  23  has a reentrant edge  26  bent at 90° and adapted to engage in the longitudinal groove  21  in the lateral wall  19  of the base section. The longitudinal groove  21  and the reentrant edge  26  form forcible nesting closure means. Forcible nesting is possible in particular because of sufficient flexibility of the lateral wall  19 . 
     The base section and the cover section at least are preferably made from a semirigid plastics material, like most wiring trunking available in the trade, this material lending itself to this type of forcible nesting closure. The flexible strip  16  which constitutes the hinge is made from a material which is more deformable than the base section and the cover section, and even from a slightly elastic material, for example an elastomer material. 
     However, in this example, the strip  16  constituting the hinge  15  is coextruded at the same time as the base section and the cover section, using a two-material coextrusion process well known in the art. The trunking  11  is therefore formed in a single extrusion operation. 
     According to an important feature of the invention, the trunking  11  includes a rib  29  and a groove  30  on respective opposite sides of the longitudinal direction of the strip  16  constituting said hinge. 
     To be more precise, in this example, the rib  29  is part of the cover section and the groove  30  is part of the base section. The opposite configuration is naturally possible. 
     Be this as it may, when the cover section is closed, the rib  29  engages in the groove  30  to establish a stiffening structure  35  around the flexible strip  16 . This can be seen more clearly in FIG. 3, which shows that when the cover section is closed the two lateral walls  19 ,  20  of the base section and the two lateral walls  23 ,  24  of the cover section nest within each other so that any forces subsequently applied to the trunking are entirely absorbed by the base section and the cover section, without deformation, the hinge being “backed up” by the stiffening structure  35 , which relieves it of all stresses and deformation. 
     In this example, the rib  29  is a reentrant edge of the cover section  13  and the groove  30  is formed along a reentrant edge of the base section. The reentrant edge of the cover section is at the edge of the lateral wall  24  to which the hinge is connected and the reentrant edge of the base section is at the edge of the lateral wall  20  of the base section to which the same hinge is connected. The two reentrant edges are oriented at substantially 45° toward the inside of the walls which respectively carry them. The groove  30  has a hook-shaped profile open toward the path of movement of the reentrant edge of the cover section when the latter is closed. 
     FIG. 1 shows the trunking wide open with the cover section and the base section substantially perpendicular to each other. 
     For a predetermined position of the cover section, shown in FIG. 2, the edge of the rib  29  comes into contact with the edge of the groove  30 , which defines a stable position of the cover section  13  relative to the base section  12 . 
     Under these conditions, the trunking can be closed only by lightly forcing the closure beyond this stable position, which results in slight stretching of the material constituting the strip  16  forming the hinge. When this stable partly open position is passed, the forcible nesting closure means  21 ,  26  on the lateral walls  19 ,  23  cooperate, thanks to slight flexing of the lateral walls, until the cover section is forcibly nested with the base section, as shown in FIG.  3 . 
     FIGS. 4 and 5 show another embodiment of the invention in which structural components analogous to those of FIGS. 1 to  3  carry the same reference numbers with the suffix a. As previously, the forcible nesting closure means opposite the hinge include a longitudinal groove  21   a  opening to the outside of the lateral wall of the base section and a reentrant edge  26   a  (at 90°). The upper edge of the lateral wall  19   a  and the reentrant edge  26   a  are rounded to facilitate forcible nesting on closure. On the same side as the strip  16   a  forming the hinge  15   a,  the rib  29   a  on the cover section is a separate part attached to a lateral wall  24   a  of the cover section substantially perpendicularly thereto (it forms a kind of hook when seen in cross section). It is shaped to engage in a groove  30   a  with a substantially U-shaped profile attached laterally, here close to its base, to a longitudinal edge of the lateral wall  20   a  of the base section. 
     As can be seen in the drawings, the inside flange  32   a  of the groove is slightly curved toward the outside and the outside flange  33   a  is lower than the inside flange. 
     As in the previous example, the hinge is made from a material relatively more flexible than that of the base section and the cover section. The trunking as a whole is made by two-material coextrusion. 
     As previously, the rib and the groove are shaped to define a stable partly open position of the cover section shown in FIG.  4 . In this position, the edge of the rib  29   a  bears on the edge of the outside flange  33   a  of the groove. However, if the cover section is forced toward its closed position, slight stretching of the hinge leads to forcible nesting of the rib into the groove in the position shown in FIG.  5 . 
     In this position, the base section  12   a  and the cover section  13   a  are rigidly nested on each side of the trunking throughout its length and the hinge  15   a  is protected from deformation by the cooperation of the rib  29   a  and the groove  30   a.    
     FIGS. 6 and 7 show a further embodiment, which is currently a preferred embodiment, in which analogous structural components carry the same reference numbers with the suffix b. This embodiment therefore includes a base section  12   b  with a globally U-shaped profile and a cover section  13   b  also with a globally U-shaped profile. 
     The base section  12   b  includes a plane wall  18   b  in the form of a strip forming the base of the trunking and two lateral walls  19   b,    20   b  extending longitudinally and globally perpendicular to the wall  18   b.  Similarly, the cover section  13   b  includes a strip  22   b  extended by two longitudinal lateral walls  23   b,    24   b  approximately perpendicular to the strip  22   b  and respectively cooperating with the lateral walls  19   b,    20   b  of the base section. 
     In this example, the lateral walls  19   b,    20   b  of the base section are similar and symmetrical about a median plane of the trunking. Likewise the lateral walls  23   b,    24   b  of the cover section. In this example, the hinge  15   b  is attached to the walls  20   b,    24   b  of the base section and the cover section which are aligned with each other on one side of the trunking when the cover section is clipped onto the trunking (see FIG.  7 ). The hinge  15   b  is advantageously an adhesive tape. 
     On the side opposite the hinge, the lateral wall of the trunking includes a longitudinal groove  21   b  opening onto the outside face of that lateral wall and the edge of the corresponding lateral wall  23   b  of the cover section includes a reentrant edge  26   b  at 90° shaped to engage in the longitudinal groove. 
     The longitudinal groove  21   b  and the reentrant edge  26   b  form forcible nesting closure means, thanks in particular to the flexibility of the lateral wall  19   b.    
     The edge of the lateral wall of the base section includes a rounded bead  36   b  which facilitates forcible nesting of the cover section with the base section. 
     On the same side as the hinge the arrangement is similar, i.e. the lateral wall includes a groove which constitutes the groove  30   b  of the stiffening structure and the edge of the lateral wall of the cover section includes a reentrant edge at 90° which constitutes the rib  29   b  of the stiffener structure. In this embodiment, the stable partly open position of the cover section is obtained when the reentrant edge encounters the lateral wall  20   b  of the base section in the immediate vicinity of the groove  30   b.  This is shown in FIG.  6 . 
     By pressing on the cover section to force it toward its completely closed position, the reentrant edge (the rib  29   b ) is caused to engage in the groove  30   b.    
     In the FIG. 8 variant, the base section  12   c,  the cover section  13   c  and the hinge  15   c  are coextruded, as explained with reference to the previous embodiment.