FR2743451A1 - Variable length box for electric cables set into concrete walls - Google Patents

Abstract

The box is in the shape of a cylinder, and has several regions along its length. The bottom end has two telescopic sliding parts (14,15,16) inside the end cylinder. The telescopic parts are initially in the fully extended position and are fixed by breakable joints. The upper end (11) is attached to the telescopic parts by an elastic region (151,152) which initially deforms when the assembly is placed in compression, but reach a limiting position where the compressive force is then transmitted to the telescopic part, causing the breakable joints to rupture and allowing shortening of the box. The different parts have joints that rupture at different compressive forces.

Description

VARIABLE DIMENSION COLUMN HOUSING FOR
ELECTRICAL APPLIANCES
The present invention relates to a columnar box of variable size for electrical equipment for the prefabrication of networks, in particular of electrical pipes put in place before pouring concrete, especially in formwork during the construction of a building.

 Enclosures for electrical devices are known in particular from French patent application 2,691,298 and from French patent application 2,668,864. The housings taught by this prior art are generally attached to a flexible deformable structure which makes it possible to absorb bending forces and a dimension variation of between 3 and 25 mm when closing the forms. In the devices of this prior art each box must be designed and produced for a determined wall thickness. However in residential constructions the walls can vary in a thickness range between 140 and 210 mm. This requires having several types of boxes adapted to different possible dimensions in addition to the acceptable variation range of 3 to 25 mm provided for the box.

 The first object of the invention is therefore to overcome this drawback of the prior art and to propose housings which are self-adaptable whatever the thickness of the wall.

 This first object is achieved by the fact that the column casing for electrical apparatus is characterized in that it is connected by its bottom and an elastic intermediate element to a column of at least two elements which can be fitted into each other after rupture of the link that unites the nestable elements.

 According to another particular feature, the box or the column comprises means adapted to receive a magnet or another fixing element.

 According to another particular feature, the first nestable element is adjacent to the elastic intermediate element which is characterized in that the maximum compression is of a determined length Z, this deformation giving a determined reaction force F2, and that each time the deformation Z is reached the elastic element no longer has this spring function and any additional compression passes through the other elements of the housing, in particular the rupture zones.

 According to different embodiments, the elastic intermediate element can be made either as an integral element of the molded plastic case, or with at least one piece of metal spring added.

 According to another particular feature, the second nestable element adjacent to the first element is connected to the latter by a rupture zone for a determined force F4.

 According to another particular feature, the third nestable element is connected to the second by a rupture zone for a determined force F3.

 According to another particular feature, the second nestable element slides on the first nestable element with a length different or equal to that of sliding of the third nestable element on the second element.

 According to another particularity, the sliding lengths are determined by an external stop integral with the first nestable element and respectively by an external stop solid with the second nestable element.

 According to another variant, the lengths are determined by an internal stop integral with the second nestable element and a second internal stop integral with the third nestable element.

 According to another characteristic, a compression of the elastic intermediate element with a length V for example of the order of 5 mm results in a reaction force having a determined minimum value F1.

 According to another particularity, the other compression or rupture forces are for F2 equal to or greater than F1, and for F3 strictly between F2 and F4.

 According to another particular feature F1 is of the order of 50 kg.

 According to another particular feature F4 is less than 200 kg.

 According to another particular feature, the interval between F2 and F3 and the interval between F3 and F4 are of the order of 20 kg minimum.

 According to another particularity, the nestable elements are provided with regularly spaced holes on the periphery and the length.

 According to another particular feature, the arrangement of the holes is provided so that after fitting one or more interlocking elements the holes of the interlocking elements remain aligned.

Other features and advantages of the present invention will appear more clearly on reading the description below made with reference to the accompanying drawings in which
Figure 1 shows a perspective view in partial section of the column housing according to the invention;
2 shows a perspective view of a variant of the upper part of the housing according to the invention;
Figures 3 and 4 show a sectional view of the alternative uses of the column housing according to the invention.

 FIGS. 5A to 5D each represent a sectional view of the different compression configurations, which allow the housing to adapt to the different closing dimensions of the forms.

 FIG. 6A represents a diagram of the reaction forces (F1, F2, F3, F4) obtained as a function of the deformations shown in FIG. 5.

 FIG. 6B represents the same diagram applied to a specific example of embodiment of the column box.

 The invention will now be described in conjunction with FIGS. 1, 5, 6A and 6B. As an example, Figure 6B shows the following values for the reaction forces and the compression and uncompressed case lengths: F1 = 50 kg, Flb = 93 kg, F2 = 100 kg, F3 = 140 kg, F4 = 180 kg, X = 205 mm, Y = 20 mm, Z = 18 mm, V = 5 mm, U = 15 mm. The column casing (11) (14 to 16) according to the invention consists of cylindrical walls (11) connected by an elastic element, produced for example with a double truncated cone, (151, 152) to a bottom wall (13). The elastic element (151, 152) mounted head to tail is connected by each of its bases on the one hand to the housing (11) and on the other hand to a nestable cylindrical element (14) forming a column. This hollow column (14) is extended at its end opposite the elastic element by a second interlocking element (15) of determined length Y and whose internal diameter is equal to or greater than the external diameter of the first element.

The edge adjacent to the first nestable element (14) is connected to a first end of the second nestable element (15) by a link (145) constituting a rupture zone which is liable to yield under a force F3, which in the example given is 140 kg.

 The second nestable element (15) is connected by its other end to a third nestable element (16) whose internal diameter is equal to or greater than the external diameter of the second nestable element (15). This third interlocking element (16) is connected to the second interlocking element (15) by a junction zone (156) which constitutes a rupture zone capable of yielding under a force F4, which in the example given is 180 kg. At the end of the second interlocking element (15) close to the first interlocking element (14) and adjacent to the rupture zone (145), the second interlocking element (15) has a stop (152). At a distance Y of l end of the first interlocking element (14) adjacent to the second interlocking element (15) is integral with the first interlocking element (14) a peripheral stop (142) which makes it possible to stop the sliding of the second element once the link (145) is broken . Finally the second element (15) has a height Y allowing the sliding of the third nestable element (16) on this second element of a length Y. The first element (14) is also connected to the housing (11) by a deformable element (151, 152) with double truncated cone and comprising a membrane (13) in the center of the small base of the truncated cones. This deformable element (151, 152) is liable to collapse over a length Z resulting in a reaction force F2, which in the example given is 100 kg. Each time this deformation is reached, the elastic element no longer has the spring function and any additional compression takes place through the other elements of the housing, in particular the rupture zones. Each of the nestable elements (14, 15, 16) has openings (141, 151, 161) regularly distributed along the periphery and along the length, the dimension and the distribution of these openings (141, 151, 161) are studied so that when the first, the second and the third element (14, 15, 16) are nested one inside the other, the openings (141, 151, 161) of each of the elements for the nested parts are in vis-å- screw each other and thus provide a passage for concrete pouring. The casing thus formed easily allows to adapt to the variable dimensions between the forms (3, Figures 3 and 4) according to the width of the partitions that one wants build up.

A magnetic plug (2) enabling the column casings (11) to be held on the forms (3) can be inserted either in the casing (11, FIG. 3) or in the third nestable element (26).

 The column box (11 to 16) must be slightly larger than the maximum thickness of the walls or partitions concerned. In the example given, the maximum thickness of the targeted walls is 200 mm, and thus the column box has a length X of 205 mm. The column box (11 to 16) is mounted by means of a magnet (2) or any other device such as a cover on one side of a pair of open forms.

 When the forms are closed so as to form the mold, they are stopped when the distance between the two walls corresponds to the desired thickness of the wall, for example 200 mm. In this case the column casing is compressed by a length V, causing a reaction force F1. In the example, V is 5 mm and F1 is 50 kg. The compression will be absorbed mainly by the spring elements (151, 152). This force must be sufficiently high so that the housing remains in place when the concrete is poured and then vibrated, since the force of the magnet or of the fixing means or the like is not always sufficient. In fact, in certain cases, the housing can remain compressed between the formwork for several days (weekends, public holidays, etc.) before the concrete is poured. In such a case, the plastic relaxes and the force F1 decreases substantially. Even in this case, the force F1 must remain sufficient to keep the box in place. Normally an F1 force greater than or equal to 50 kg is sufficient to achieve this functionality.

 In the case where the desired thickness is 190 mm, the box must be compressed by 15 mm causing a reaction force Flb greater than F1. In this case the box will be held more securely than in the previous case. Similarly, the deformation will be mainly absorbed by the spring element (151, 152). In the example given Flb is 93 kg. If the forms are brought closer together, the flexible element (151, 152) will be compressed until the upper part (152) of the telescopic column (14 to 16) touches the bottom of the box (11).

Thus the possibility of compressing the elastic element is exhausted. The reaction force and the deformation at this point are named F2 and Z in the preceding description and in the diagram of FIG. 6A. In the example given, FIG. 6B, F2 is 100 kg and Z is 18 mm.

 Since the elastic element is now inoperative, any additional compression will pass through the rigid parts of the housing. Thus the reaction force will increase rapidly when the forms continue to approach in order to arrive at the level of the desired wall thickness.

 In fact, after a few tenths of a millimeter of additional compression, the reaction force reaches the value F3 for which the weaker of the two rupture zones of the telescopic element (14 to 16) yields. In this case it is in the example of the link (156) between the second and the third element as shown in Figure 5C. After the rupture of the link (156) the telescopic element (16) close to the rupture zone slides of a length Y over the next element (15), driven by the reaction force. The rigid part of the column housing therefore becomes shorter, thus allowing the spring element (151, 152) to open again. In the example given Y is 20 mm and in any case Y must be greater than Z.

 If the formwork stops at a dimension between them of 180 mm, the case of length 205 mm of the example will have lost 20 mm of its original length due to the collapse of the first rupture zone and the subsequent telescopic effect . So that the housing can adapt to 180 mm, the flexible element will be compressed again with a length V of 5 mm, giving a reaction force F1 of the order of 50 kg, the same as for a dimension of 200 mm.

This force F1 being sufficient to hold the housing in place.

 By looking at FIG. 6B, it is understood how the column box of the example can also adapt to dimensions less than 180 mm, in this case the dimensions of 170, 160 and 150 mm.

The operation is cyclical in nature and similar to the adaptation to higher dimensions. The key points are as follows
If the formwork stops at a dimension between them of 170 mm, the case of length 205 mm of the example will always have lost 20 mm of its original length due to the collapse of the first rupture zone and the telescopic effect consecutive. Thus so that the housing can adapt to 170 mm, the flexible element will have to be compressed again by 15 mm, giving a reaction force Flb. The compression of the flexible element and the reaction force will therefore be the same as for a dimension of 190 mm.

 By going from a dimension of 170 mm to 160 mm, the reaction force will have exceeded the level F4, in this case 180 kg, and, in a very similar way to what happened between 190 mm and 180 mm, the second rupture zone will have given way allowing one telescopic element to be housed in another. Thus the case of length 205 mm in the example will now have lost the other 20 mm of its original length, which means 40 mm in total.

In order for the housing to be able to adapt to 160 mm, the flexible element will therefore have to be compressed again by 5 mm, giving a reaction force F1. Thus the values of the latter will be the same as for a dimension of 200 or 180 mm.

 Finally, if the formwork stops at a dimension between them of 150 mm, the housing of length 205 mm in the example will always have lost 40 mm from its original length due to the collapses of the two rupture zones and the consecutive telescopic effects. So that the housing can adapt to 150 mm, the flexible element will have to be compressed again by 15 mm, giving a reaction force Flb. The values of this force will therefore be the same as for a dimension of 190 or 170 mm.

 Given that the thickness ratings of the wall or partition from 150 mm to 200 mm are by far the most common, we therefore understand that thanks to this system, a column box can thus be automatically adapted to the thicknesses most important wall or partition with a single box, without reducing the forces holding the box between the forms.

It is obvious that the examples of force values
F1, F2, F3, F4 have been given for illustrative purposes and are not limiting. We can very well design boxes operating on the same principle for different force values.

It is also evident that the maximum dimension
X of the housing can be modified. Similarly, the dimension Y of the second element (15) may be different from that Y at which the stop (142) for stopping the nesting of the second element (15) on the first (14) is arranged to modify the possible dimensions. of the column (14, 15, 16). Finally, the dimension Z corresponding to the maximum deformation of the spring can be adapted. The box (11) of FIGS. 1, 3, 4 and 5 has been shown in simplified form and it is obvious that this box (11) can also include the interior and exterior arrangements shown in FIG. 2.

 Thus the housing (4, Figure 2) whose side walls (41) extend the column and the bottom (42) has a sleeve (44) which allows the connection with the column (16). This connection can be made by projecting lugs or by clamping or clipping or any other means between the additional box (41) and the column (16) of sectionable elements.

 The housing (11) of FIGS. 1, 3, 4 and 5 is shown diagrammatically without the internal groove or groove (414) shown in FIG. 2 which allows the clipping onto the housing of a cover for fixing to wooden formwork but it It is obvious that this box (11) of Figures 1, 3, 4 and 5 can be provided. Finally the end pieces for tube (412, 413, FIG. 2) closed by a breakable cover (4131, 4121) and arranged in a plane perpendicular to the plane passing through the axis of symmetry of the recesses (411) formed in the junction plane of the mold can also be provided on the housing (11).

Similarly sectors (415) in truncated cone and having a plurality of different sections in staircase to allow the use of claw devices can also be provided on each housing (11)
Other modifications within the reach of the skilled person are also part of the spirit of the invention.

Claims (16)

 1. Casing (11) with column for electrical apparatuses characterized in that it is connected by its bottom (12) and an elastic intermediate element (151, 152) to a column of at least two interlocking elements (14, 15, 16) into each other after the link between the nestable elements has been broken.  2. Column casing for electrical apparatus according to claim 1, characterized in that the casing or the column comprises means adapted to receive a magnet or another fixing element.  3. Column casing for electrical apparatus according to claim 1 or 2, characterized in that the first interlocking element is adjacent to the elastic intermediate element which is characterized in that the maximum compression is of a determined length Z, this deformation giving a determined reaction force F2, and that each time the deformation Z is reached the elastic element no longer has this spring function and any additional compression passes through the other elements of the housing, in particular the rupture zones.  4. Column housing for electrical apparatus according to one of the preceding claims, characterized in that the elastic intermediate element can be made either as an integral element of the molded plastic housing, or with at least one piece of metal spring added.  5. Column casing for electrical equipment according to one of claims 1 to 4, characterized in that the second nestable element (15) adjacent to the first element (14) is connected to the latter by a rupture zone for a determined force F4.  6. Column housing for electrical equipment according to claim 5, characterized in that a third interlocking element (16) is connected to the second (15) by a rupture zone for a determined force F3.  7. Column housing for electrical apparatus according to claim 5, characterized in that the second nestable element (15) slides on the first nestable element (14) of a length different or equal to that of sliding of the third element (16) nestable on the second element (15).  8. Column housing for electrical apparatus according to claim 6, characterized in that the sliding lengths are determined by an external stop (142) secured to the first nestable element (14) and respectively by an external stop (152) secured to the second nestable element (15).  9. Column housing for electrical apparatus according to claim 6, characterized in that the lengths are determined by an internal stop secured to the second nestable element and a second internal stop secured to the third nestable element.  10. Column casing for electrical apparatus according to one of claims 1 to 9, characterized in that a compression of the elastic intermediate element with a length V for example of the order of 5 mm results in a reaction force having a determined minimum value F1.  11. Column casing for electrical apparatus according to one of claims 3 to 5 and 9, characterized in that the other compression or rupture forces are for F2 equal to or greater than F1, and for F3 strictly between F2 and F4.  12. Column housing for electrical apparatus according to claim 10, characterized in that F1 is of the order of 50 kg.  13. Column casing for electrical apparatus according to claim 10 or 11, characterized in that F4 is less than 200 kg.  14. Column box for electrical apparatus according to one of claims 1 to 11, characterized in that the interval between F2 and F3 and the interval between F3 and F4 are of the order of 20 kg minimum.  15. Column casing for electrical apparatus according to one of claims5 to 9, characterized in that the interlocking elements are provided with regularly spaced holes on the periphery and the length.  16. Column casing for electrical equipment according to claim 15, characterized in that the arrangement of the holes is provided so that after fitting one or more interlocking elements the holes of the interlocking elements remain aligned.