FR2945386A1 - CABLE TRAY ASSEMBLY AND METHOD FOR MANUFACTURING AND MOUNTING THIS ASSEMBLY. - Google Patents

Abstract

The assembly includes a metal body (14) closed by at least first and second metal cover members (28, 30) provided with adjacent longitudinal ends (28A, 30A). The adjacent end (28A) of the first cover member overlies the adjacent end (30A) of the second cover member such that the adjacent ends (28A, 30A) are provided with surface facing surfaces (SF, SM) creating a baffle effect attenuating the penetration of an electromagnetic field into the body (14). This assembly also includes at least one metal clip forming a clamping clip of a cover member (26) on the body (14). This clip contributes to the limitation of the spacing of the cover surfaces (SF, SM) by opposing the bending of the cover member (26). At least one end of the clip has claw means for scratching and piercing any body coating (14) to provide electrical contact between the clip and the body.

Description

The present invention applies to the field of cable tray assemblies, the cables can carry strong or weak currents. Already known in the state of the art a cable tray assembly, of the type comprising a body closed by at least first and second cover members provided with adjacent longitudinal ends. In what follows, we will designate by longitudinal direction the general direction of the path of a cable in the raceway. In addition, a length will be defined as a dimension measured in the longitudinal direction. The body and the cover elements of an assembly such as above provide effective mechanical protection of the cables housed in the assembly. However, it is sometimes necessary to install the cable tray assembly in an environment likely to be subjected to electromagnetic interference, particularly in the form of an electromagnetic field pulse (from a source close to the whole forming a cable tray) momentarily creating an electric field that can generate interference in the cables likely to disturb electrical components to which they are connected. In this case it is desired to protect the cables housed in the raceway against electromagnetic interference. Already known in the state of the art a cable tray assembly of the aforementioned type, wherein the body and the lid elements are metallic. In such a metal assembly, the mechanical protection of the cables is effectively ensured. However, the electromagnetic protection of the cables remains insufficient, this in spite of the metallic structure of the assembly likely to form a Faraday cage. In fact, in general, the adjacent ends of the cover elements are abutted edge to edge in such a way that the abutment edges form, in the assembly containing the cables, transverse slots with respect to the path of the cables which strongly limit the protection. against an electromagnetic field pulse. FR-A-2 692 731 and US-A-2005/0087358 each propose a cable tray assembly provided with metal means forming a Faraday cage. However, these sets are complex and relatively difficult to mount. The object of the invention is to provide a cable-structure assembly of simple structure, providing effective protection of the cables with respect in particular to high electromagnetic disturbances. For this purpose, the subject of the invention is a cable tray assembly, of the type comprising a metal body closed by at least first and second metal cover elements provided with adjacent longitudinal ends, characterized in that 2945386 -2- the adjacent end of the first cover member overlies the adjacent end of the second cover member such that the adjacent ends of the first and second cover members are provided with overlapping surfaces creating a baffle effect attenuating the penetration of a cover member; electromagnetic field in the body.

The baffle effect is achieved by imposing a large amount of overlap area relative to the gap between these overlapping surfaces. The skilled person can therefore choose the length of the overlapping surfaces depending on the attenuation he wishes to obtain. The desired attenuation can preferably be at least 10 dB.

There is generally electrical contact between the cover surfaces, but this contact is not necessary for the efficiency of the baffle effect. It is therefore not necessary to provide on the covering surfaces clamping means of these surfaces ensuring large and precise clamping forces, which simplifies the structure of the cable tray assembly according to the invention.

Furthermore, any longitudinal slots (parallel to the general direction of the path of the cables in the cable tray assembly) generally do not interfere with the protection of the cables against an electromagnetic field, this in contrast to the transverse slots. Thus, the removal of the transverse slots by overlapping the joining ends of the cover members is sufficient to greatly increase the electromagnetic protection provided by the cable tray assembly. The possibility of leaving longitudinal slots, particularly between the body and the cover elements, simplifies the structure of the cable tray assembly of the invention. Finally, it should be noted that the structure of the lid elements of the assembly according to the invention is very simple and can easily be adapted to a conventional assembly body forming a cable tray. According to other optional features of the cable tray assembly according to the invention: the adjacent end of the first cover element has a generally U-shaped shape, so as to comprise a core connecting two wings, and, in which, the adjacent end of the second cover member has a generally planar shape to be nested under the core of the adjacent first end and between the wings of the adjacent first end; the covering surfaces each have a substantially constant width over their entire length, this length being at least equal to 6% of this width, this length being for example equal to 5 cm for a width of between 6 and 6 cm; and 61 cm; the cover elements are manufactured in sheet blanks, preferably aluminum, with a thickness of less than or equal to 1 mm, preferably equal to 0.5 mm; the assembly comprises at least one metal clip forming a clamping clip of a cover member on the body, this clip comprising first and second gripping ends in contact with the body respectively and a cover member, this clip being opposing, where appropriate, longitudinal bending of the cover member; at least the first nip end comprises claw means intended to scratch and pierce any coating of the body electrically insulating said body, such as paint or varnish, to ensure electrical contact between the clip and the body. The clip has a generally clevis shape comprising a core connecting two wings forming the contact ends; - The clip is in a material adapted to that of the body or lid elements to avoid in particular redox effects. The invention also relates to a metal cover element for closing a metal body of a cable tray assembly, characterized in that it is intended to form a cable tray assembly according to the invention. The invention also relates to a method of manufacturing and mounting a cable tray assembly, the assembly being of the type comprising a metal body closed by at least first and second metal lid members 25 provided with ends adjacent longitudinal process, the method being of the type in which the cover elements are made to predetermined dimensions, characterized in that: - a cable tray assembly is manufactured in which the cover elements are manufactured in sheet metal blanks; thickness less than or equal to 1 mm, preferably equal to 0.5 mm, so that each lid member is formed in a sheet blank that can be sheared with a portable hand tool by a user, and when mounting the assembly, the dimensions of at least one cover element are adapted by shearing this cover element.

The method according to the invention facilitates the assembly of the cable tray assembly. Indeed, during assembly of the assembly, it is generally appropriate to adjust the dimensions of some of the lid elements to take into account the specific dimensions of the cable tray. The lid elements being made of a relatively thin sheet blank, it is easy to adapt their length (by shortening) by shearing them. Shearing, performed by an operator with the aid of a portable hand tool, causes almost no dust, which makes it possible to mount the cable tray assembly in a very clean environment without detriment to this cleanliness. The invention will be better understood on reading the following description given solely by way of example and with reference to the appended drawings, in which: FIG. 1 is an exploded perspective view of a first section of FIG. a cable tray assembly according to the invention; - Figure 2 is a detail view of the circled portion II of Figure 1; FIG. 3 is a view similar to FIG. 1 of a second section of the cable tray assembly according to the invention; FIG. 4 is a detail view of the circled portion IV of FIG. 1, after mounting a cover member on the body of the cable tray assembly according to the invention, showing a staple in the course of assembly on this set; Figure 5 is an elevational view of the clip shown in Figure 4; - Figure 6 is a top view of the clip shown in Figure 5; Figures 7 to 10 are top views of various cover members for use in the cable tray assembly of the invention. FIGS. 1 and 3 show two sections 12A, 12B of an assembly 12 forming a cable tray according to the invention.

The assembly 12 comprises a conventional metal body 14 of generally U-shaped shape, for example made of steel. In what follows, the identical or similar elements will be designated by identical reference numerals. The body 14 comprises various conventional elements 16 to 20, U-shaped, provided with adjacent longitudinal ends interconnected by conventional means 22. It will be noted that the body 14 comprises conventional means 24 for guiding the cables. A metal cover 26, preferably aluminum, is intended to close the body 14. This cover 26 comprises a plurality of metal elements arranged longitudinally one after the other. These cover elements are manufactured in sheet blanks, preferably aluminum, with a thickness of less than or equal to 1 mm, preferably equal to 0.5 mm. The body 14 and the cover 26 provide mechanical and electromagnetic protection for the cables intended to be housed in the assembly 12.

Referring to Fig. 1, showing the first section 12A of the cable tray assembly, it will be seen that the cover 26 comprises at least first 28 and second 30 metal cover members. The first cover member 28 includes a female longitudinal end 28A adjacent a first male longitudinal end 30A of the second cover member 30. The first lid member 28 also includes a male longitudinal end 28B adjacent to a corresponding female end of another not shown lid member. The second lid member 30 also includes a second male longitudinal end 30B adjacent to a corresponding female longitudinal end of another not shown lid member.

The first cover member 28 has a generally U-shaped straight shape. The side edges of the first cover member 28 are parallel to each other. The first cover member 28 comprises a core 28C connecting two wings 28D. Thus, the female end 28A of the first cover member 28 has a generally U-shaped profile formed by the core 28C and the two wings 28D. On the other hand, the male end 28B of the first cover member 28 is formed by one end of the web 28C extending longitudinally beyond the longitudinal ends of the wings 28D. The core 28C of the cover element 28 is intended to be placed on the free ends of the wings of the body 14 so that the wings 28D of the element 28 partially cover the wings of the body 14.

The second cover member 30 is generally planar in shape bounded by curved lateral edges about an imaginary axis Ti perpendicular to the general direction of the cable path and the plane of the sheet. The first male end 30A of the second cover member 30 thus has a generally planar shape intended to be fitted under the core 28C of the female end 28A and between the flanges 28D of this female end 28A. Thus, the female end 28A of the first cover member 28 covers the first male end 30A of the second cover member 30, so that these ends 28A, 30A are provided with cover surfaces SF, SM creating a baffle effect attenuating the penetration of an electromagnetic field into the body 14 (see Figures 1 and 2). These cover surfaces SF, SM may be at least locally in electrical contact with each other. However, the contact between the cover surfaces SF, SM is not necessary for the efficiency of the baffle effect. It will be noted that the covering surfaces SF, SM each have a substantially constant width along their entire length. Preferably the length of the covering surfaces SF, SM is at least equal to 6% of this width. For a width of the surfaces SF, covering SM of between 6 and 61 cm, an effective attenuation of the penetration of the electromagnetic field (attenuation of at least 10 dB) can be obtained with a length L of the covering surfaces SF, SM at less than 5 cm (see Figure 2). The second element 30 is intended to be placed on the free ends of the wings of the body 14.

Preferably, the male ends of the cover members are delimited by longitudinal edges forming slight recesses in width D with respect to the longitudinal edges of the cover members. Referring to FIG. 3, it can be seen that the part of the cover 26 of the second section 12B of the cable raceway assembly 12 comprises an element 32 having a generally curved shape about an imaginary axis T2 perpendicular to the direction general of the cable path and parallel to the plane of the sheet in which this element is formed. The cover member 32 comprises two male longitudinal ends 32A, 32B. In the example shown in Figures 1 and 3, the body 14 is covered with a coating electrically insulating the body, such as a paint or varnish. To fix the lid 26 on the body 14, it is preferable to use metal clips 34 forming clamps such as that shown in FIGS. 4 to 6. These clips 34 serve to tighten a lid element, for example a profiled element. U such as the element 28, on the body 14. In Figure 4, the clip 34 is shown during assembly on the assembly 12 forming cable tray. In the example shown, the clip 34 has a generally clevis shape comprising a core 34C connecting two wings 34D. The wings 34D of the clip 34 form first and second nip ends in contact with the body 14 and the cover member 28, respectively. A first flange 34D, intended to be in contact with the body 14, comprises claw means for scratching and piercing the insulating coating of the body 14, to ensure electrical contact between the clip 34 and the body 14. By Referring to Figures 5 and 6, it is seen that in the illustrated example, the claw means comprise two claws 36 each formed by a puncture formed in the wing 34D. Alternatively, the wing 34D could have only one claw 36. For reasons including simplification of mounting of the clip, it is preferably provided claw means 36 on both wings 34D of the staple 34, as shown in FIG. 5. Thus, it is possible to indifferently either of the flanges 34D in contact with the body 14. Furthermore, the claw means 36 formed on the wing 5 34D in contact with the cover 26 may scratch and drill any electrical insulating coating of the cover 26 to ensure electrical contact between the clip 34 and the cover 26. With claw means, the clip 34 provides electrical continuity between the body 14 and the lid 26 even if the body 14 or the lid 26 is covered with an insulating coating. Preferably, the clips 34 are made of a material adapted to that of the body 14 or that of the elements of the lid 26, for example steel, in particular spring steel, to avoid undesirable redox effects. To manufacture the assembly 12 forming a cable tray, in particular, the lid elements are manufactured to predetermined dimensions. Thus, all the straight elements 28 intended to form the assembly 12 may have a predetermined length, for example equal to 2.5 m. In general, when assembling the assembly 12, at least one cover element, for example the right element 28, must be shortened to fit the specific dimensions of the cable tray. Since the lid members 26 are made of a relatively thin sheet blank, it is easy to adjust the length (by shortening) of a straight member 28 by shearing one of its ends. This shearing can be performed by an operator using a portable hand tool easy to handle. In addition, shearing causes practically no dust, or any material debris, which makes it possible, if necessary, to respect an environment with a very high stress of cleanliness. It is also possible to shear any other element of the lid 26 to fit the specific dimensions of the cable tray. To secure the lid 26 to the body 14, the lid members 26 are clamped to the body 14 by means of staples 34. It should be noted that the lid members having no female ends are retained on the body 14, on the one hand, by cooperation of their male ends with the female ends of the adjacent lid members, and on the other hand, by the clips 34. An appropriate number of clips 34 are placed on the lid members 26 and the body 14 so as to ensure good mechanical retention of the lid 26 on the body 14. The lid members 26, produced in a relatively thin sheet blank, tend, if they are relatively long, to to bend longitudinally, that is to say to bend slightly around an imaginary axis perpendicular to the general direction of the cable path and the plane of the sheet.

However, cover elements made from sheet blanks between 0.5 and 1 mm thick, provided with 5 cm long overlapping surfaces SF, SM, have a sufficient rigidity for the spacing of the surfaces SF, SM does not exceed about 1 mm, which guarantees an efficient baffle effect. The lid members are even more rigid when they have side wings 28D. Indeed, these wings form stiffening means of the lid elements. In the case of lid members without lateral wings, the bending tends to undesirably widen the longitudinal slots (parallel to the general direction of the cable path) between the body 14 and the lid members having no wings. side. However, by placing an appropriate number of staples 34 on these cover elements (without side wings) and the body 14, it limits the widening of these longitudinal slots (the staples 34 oppose bending). This prevents the penetration of an electromagnetic field into the body through these longitudinal slots, the width of which is limited for example to less than 1 mm thanks to the clips 34. In FIGS. 7 to 10, various cover elements are shown. may be used in the assembly 12 forming a cable tray. The longitudinal ends of the elements shown in Figs. 7 to 10 are intended to be adjacent to ends of adjacent lid members, and are all male ends. In Figure 7, there is shown a cover member 38 having a generally planar and straight shape. The side edges of this cover member 38 converge from a first male end 38A to a second male end 38B. In FIG. 8, there is shown a cover member 40 which, unlike the element 38 shown in FIG. 7, comprises two parts 42, 44 with parallel lateral edges interposed respectively between, for the part 42, a male first end 40A and a central portion converging side edges and, for the portion 44, a second male end 40B and the central portion with converging side edges. In FIG. 9, there is shown a lid member 46, generally T-shaped, comprising three male ends 46A, 46B, 46C. In Figure 10, there is shown a cover member 48, generally cross-shaped, comprising four male ends 48A, 48B, 48C, 48D. Among the advantages of the invention, it will be noted in particular that the cover surfaces SF, SM create a baffle effect which effectively attenuates the penetration of an electromagnetic field into the body 14, by using manufactured cover elements. in a relatively thin sheet metal blank, of easy to adapt length (by shearing with a hand tool causing almost no dust), the clips 34 forming very simple means opposing the longitudinal bending of the elements of cover without side wings.

It should also be noted that the elements of the cover 26 have very simple structures and shapes and are capable of adapting to conventional cable tray bodies, without it being necessary to modify these cable tray bodies. Finally, it should be noted that the cover elements 26 can be mounted on the cable tray body at the end of the worksite, without producing any dirt. The function of protecting the cable tray against electromagnetic pulses can therefore be put in place, at the end of the construction site, in a clean environment, without contaminating this environment.

Claims (10)

REVENDICATIONS1. Cable tray assembly, of the type comprising a metal body (14) closed by at least first and second metal cover members (28, 30, 32, 38, 40, 46, 48) (26) provided with longitudinal ends adjacent (28A, 30A), characterized in that the adjacent end (28A) of the first cover member overlies the adjacent end (30A) of the second cover member, so that the adjacent ends (28A, 30A) of the first cover member and second cover members are provided with cover surfaces (SF, SM) creating a baffle effect attenuating the penetration of an electromagnetic field into the body (14). 2. The assembly of claim 1, wherein the adjacent end (28A) of the first cover member has a generally U-shaped shape, so as to comprise a core (28C) connecting two wings (28D), and wherein the adjacent end (30A) of the second cover member has a generally planar shape to be nested under the web (28C) of the adjacent first end (28A) and between the wings (28D) of the adjacent first end ( 28A). 3. The assembly of claim 1 or 2, wherein the covering surfaces (SF, SM) each have a substantially constant width over their entire length, this length being at least equal to 6% of this width, this length being for example equal to 5 cm for a width between 6 and 61 cm. 4. An assembly according to any one of the preceding claims, wherein the lid members (28, 30, 32, 38, 40, 46, 48) are made from sheet blanks, preferably aluminum, of lower thickness. or equal to 1 mm, preferably equal to 0.5 mm. 5. An assembly according to any one of the preceding claims, comprising at least one metal clip (34) forming a clamping clip of a cover member (26) on the body (14), this clip (34) comprising first and second second pinch ends (34D) in contact with the body (14) and a cover member (26), respectively, which clip (34) is opposed to the longitudinal bending of the cover member (26). 6. An assembly according to claim 5, wherein at least the first nip end (34D) comprises means (36) with claws for scratching and piercing a possible coating of the body (14) electrically insulating the body (14), such paint or varnish to ensure electrical contact between the staple and the body. 2945386 -11- 7. The assembly of claim 5 or 6, wherein the clip (34) has a generally clevis shape comprising a core (34C) connecting two wings (34D) forming the contact ends. 8. An assembly according to any one of claims 5 to 7, wherein the clip (34) is in a material adapted to that of the body (14) or cover elements (26) to avoid the effects of redox. 9. Element (28, 30, 32, 38, 40, 46, 48) of metal cover (26) for closing a metal body (14) of a cable tray assembly, characterized in that it is intended for forming a cable tray assembly according to any one of the preceding claims. 10. A method of manufacturing and mounting a set (12) forming a cable tray, the assembly (12) being of the type comprising a metal body (14) closed by at least first and second metal lid elements provided with adjacent longitudinal ends (28A, 30A), the method being of the type in which the lid members (26) are manufactured to predetermined dimensions, characterized in that: - a cable duct assembly (12) is produced according to claim 4, whereby each cover member is formed in a sheet blank that can be sheared with the aid of a hand-held portable tool by an operator, and - when mounting the assembly (12), is adapted the dimensions of at least one cover member (26) by shearing this cover member.