CH622851A5 - Electric fence element - Google Patents

Description

The present invention relates to a fence element for an electric security fence, which comprises a frame and at least one double conductor of the type described below and which is arranged in said frame in the form of a mesh network.

The term double conductor used in the present description should be understood as designating a combination of at least two elongated members, electrically conductive, one of these members being wrapped or provided with a thin sleeve or layer in an insulating material. This double conductor preferably consists of a strand or of a cable formed of several filaments, one of the filaments of the strand or of the cable being wrapped in a thin insulating layer or provided with such a layer. These double conductors can be produced easily and inexpensively; this is particularly true with regard to the embodiment in the form of a strand or cable, these being able to be manufactured on conventional cabling machines. The conductor, for example in the form of a strand or cable, is preferably wrapped in an anti-corrosion coating such as, for example, a synthetic material.

Such a composite conductor, intended for use in a security fence, is constituted such that when a pressure is applied to this conductor, at least one of the electrical properties, in particular the contact resistance between its members, is changed by a measurable amount. The security fence therefore comprises at least one conductor as described above, a circuit connected to the two conductive members in order to detect a variation with respect to the nominal value of at least one of the electrical properties, in particular the contact resistance, and a warning device controlled by said circuit. This offers the certainty that any impact on a fence made up of such a conductor, or such conductors, causing a measurable change in the contact resistance between the constituent members of the double conductor or conductors, is thus immediately detected.

It is thus impossible to destroy such a fence, for example by cutting, without this being noticed. The security fence can in particular be made up of fence elements as described above.

A drawback of such a fence element comprising a frame and at least one conductor of the aforementioned type, which is arranged in said frame in the form of a mesh network, is that there is the possibility of moving or shifting the double conductors interleaved with each other. It is thus possible to make in the element of a security fence openings of an unacceptable size that can provide access to intruders without, for example, the contact resistance between the organs being changed in a measurable way or without the warning device being activated.

The object of the invention is to eliminate this drawback. The object of the invention is described in claim 1. According to a preferred embodiment, these crossing points are produced by folding at an angle of at least 180 ° relative to the plane of the frame, so as to achieve each crossing point two loops through which extend said double conductors.

These conductors are preferably stretched horizontally. The characteristics and advantages of the invention will become apparent during the description which follows, made with reference to the appended drawing given solely by way of example and in which:

fig. 1 is a view of a double conductor used in a fence element according to the invention;

fig. 2 is a view of a first embodiment of a fence element according to the invention, and FIG. 3 is a view of a second embodiment of a fence element according to the invention.

Fig. 1 shows a double conductor 1 as used in a fence element according to the invention. This conductor 1 is, in this example, composed of a number of strands 2, so that one of the filaments of a strand is wrapped or provided with a thin insulating layer 4. The assembly of the double conductor, or cable, is surrounded by an anticorrosive coating 5 of a synthetic material. The filament 3 wrapped or provided with the insulating layer 4 and the other filaments together respectively form the two elements or organs conducting the double conductor.

Fig. 2 shows a first embodiment of a fence element 6 according to the invention. The closing element 6 comprises a frame comprising two uprights or vertical sides 7 and two horizontal or longitudinal sides 8. The vertical sides 7 are hollow tubes whose front wall is removable and is fixed by means of bolts and nuts on the back wall. In this context, a number of double conductors 9 of the type described above are interleaved between the lateral uprights 7. These conductors 9 can be separate sections of double conductors, so that the conductive members of the separate sections of double conductors are connected in series. The electrical connections between the conductors 9 are located inside the hollow tubes 7. It is also possible to tension a conductor 9 in the frame so as to form a mesh network.

To prevent mutual displacement of the interlaced conductors at their crossing points, the frame 6 comprises a number of horizontal double conductors 10. The conductors 10 are made in the same way as the conductors 9. The two conductive elements of the conductors 9 and conductors 10 are connected in series, so that the connections between conductors 9 and 10 are arranged inside the hollow tubes 7. It is obvious that the conductors 10 need not be horizontal. The conductors 10 can also be stretched through a row of cross points 11 which are aligned obliquely in the plane of the frame 6. Similarly, the conductors 10 can follow an arbitrary path through a number of cross points of the mesh network.

Fig. 3 shows, on a larger scale, parts of the two lateral portions of a preferred embodiment of fence element 6 according to the invention. The embodiment shown in

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622,851

fig. 3 is produced in approximately the same way as that shown in FIG. 2. In addition, in the embodiment of FIG. 3, the crossing points 11 in a certain number of rows of two interlaced double conductors 9 are bent at an angle of 180 ° relative to the plane of the frame 6, so as to form two 5 loops 12 per crossing point 11. The horizontal double conductors 10 are arranged through the loops 12. It is understood that, in this case also, it is not essential that each conductor 10 extends through a horizontal row of crossing points. This embodiment of the invention is particularly advantageous in that it provides a mesh network whose meshes can no longer be displaced with respect to each other and in which the conductors are practically subjected to no pressure.

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1 sheet of drawings

Claims (3)

622,851 1. Fence element for electric security fence, comprising a frame and at least one double conductor comprising at least two conductive elements, one of which is enveloped in a thin insulating layer, said double conductor having at least one electrical characteristic sensitive to the applying pressure and being arranged in said frame in interlaced form, the fence element comprising means for preventing the displacement of the crossing points of the interlaced double conductors, characterized in that said means consist of double conductors ( 10) of the same type as the interlaced conductors (9) of which the fence element (6) is made, and which extend through the points (11) of crossing of two interlaced conductors (9) and are electrically connected to the or to the interleaved conductors (9) of the fence element. 2. Fence element according to claim 1, characterized in that at the crossing points (11) the double conductors are folded or folded at an angle of at least 180 ° relative to the plane of the frame (6), so forming at each crossing point (11) two loops (12) through which the double conductors (10) extend. 2 3. Fence element according to any one of claims 1 and 2, characterized in that the conductors (10) are stretched horizontally.