EP0893803B1 - Electrically conductive wire - Google Patents

Abstract

Electric conductor wire (1) comprises a synthetic, preferably polyamide, monofilament core (2) with an outer coating (3) of electrically conducting particles, preferably powdered metal or carbon, forming a continuous conducting layer covering the whole surface of the core. Preferably the core has a round, stellate or toothed cross-section, and the outer conducting layer can itself by covered with an insulating coating. The central electrical conductor is embedded inside a core of synthetic material, coated by conducting particles and covered with an insulating layer to make a coaxial cable.

Description

The present invention relates to a wire electrically conductive, this wire being intended, more particularly but not exclusively, replacement current threads or braids used for the realization electric fencing.

A first known type of fence wire electrical consists of a soul in the form of synthetic monofilament, around which is wrapped helically at least one electrically conductive wire. The synthetic monofilament, in particular made of polyamide or polyester, with a diameter of around 1 to 2 mm, is very oriented so as to have good resistance mechanical, and it is very little retracted so that it does not can't relax due to humidity, rain or solar radiation. The wires electrically one, two or more weak conductors section relative to that of the core, are wound by covering, with a greater or lesser propeller pitch, around of soul. These electrically conductive wires are made of metal or alloy, preferably steel stainless to prevent rust on contact with rain and moisture laden air.

A second known type of wire for fencing electric includes, instead of the soul of the type previous, synthetic multifilaments which are assembled, twisted and wired. In these multifilaments one or more wires are inserted electrically conductors, in particular stainless steel. This second type has the advantage of being more flexible than the first, and to require elementary threads of lesser quality.

A third type of conductor for fences electrical consists of a flat braid, more or narrower, made from multiple filaments, the some being synthetic filaments and the others being consisting of one or more electric wires conductors, inserted between the synthetic filaments, the product thus obtained being relatively solid.

In all cases, the threads or braids for electric fences therefore result from the assembly of at at least one plastic wire, so electrically insulator, and one or more wires electrically conductors, preferably stainless steel, which appear on the surface of the final product. Such sons conductors are relatively expensive and, to overcome the cost issues, manufacturers tend to reduce the diameter of these conductive wires, therefore increasing the risk of breakage of said wires, which obviously makes the electric fence unfit for its use since the continuity of the electrical circuit is then broken.

In addition, the plastic parts wires or braids for electric fences are exposed to solar ultraviolet radiation, and for increase the longevity of these threads or braids, their plastic parts are additivated with agents anti-ultraviolet. However, these agents are themselves gradually destroyed by ultraviolet rays, and after a few years, they lose their effect. So the interest of such agents remains quite low, and it must also be noted that anti-ultraviolet agents are expensive substances.

It should still be noted, from the point of view of manufacture of wires or braids for electric fences, that all known types require repeats of monofilaments or multifilaments, on wrapping, wiring or braiding, which complicates and increases the processes for obtaining these products.

We also know, from documents US 3247020 and NL 6500145, electrically conductive wires made up a core of insulating material, surrounded by a coating conductor in the form of a layer. More specifically, in the case of document US 3247020, the core is made up by a glass fiber, therefore by a mineral fiber, which is relatively brittle and difficult to adhere conductive particles, unless implement complex and costly processes. Through elsewhere, in the wire according to this document, the particles conductive alone do not form a layer continuous conductor, electrical continuity being there produced by a binder which, after appropriate treatment, forms a conductive mass creating "bridges" between the conductive particles.

Similarly, in the case of the document NL 6500145, the outer layer consists of a coating in which particles are embedded conductive, the coating being here in material synthetic, therefore insulating, which leaves some doubts on the electrical conduction qualities of the wire.

In all cases, the structure of the wire remains here complex, since it contains at least three constituents distinct, and its manufacture appears rather delicate.

The present invention aims to remedy the whole previous disadvantages, by proposing a thread electrically conductive new design and simple, usable especially as wire for fencing electric, which is simple and economical to manufacture, which is resistant to ultraviolet rays and weather conditions, and which eliminates the risk of breakage (or break in electrical continuity) of the conducting wires current.

To this end, the invention essentially has for object an electrically conductive wire, which includes a monofilament type core, of synthetic material, which is coated with an electrically formed coating conductive, alone forming a layer longitudinally continuous, electrically conductive.

The conductive coating results in particular from the application, on the outer surface of the core wire, electrically conductive metal powder or carbon.

An electrically conductive wire is thus obtained, and more particularly a conducting thread on the surface, composed of a synthetic insulating core conferring on the wire its mechanical characteristics, and of a coating conductor whose thickness determines the cross-section of passage of electric current.

The electrically conductive wire thus obtained, has good mechanical characteristics and electric. In particular, it is less fragile than a wire or conventional braid for electric fencing, the presence of a continuous conductive outer layer eliminating the risk of breakage of a low section. The conductive coating, constituting a continuous layer preferably covering all of its circumference of the plastic core, ensures total opacity to ultraviolet rays, protecting the soul against any degradation due to radiation.

Such an electrically conductive wire can be industrially obtained in a rational way and economical, the conductive coating can be applied on the plastic core by a process of coextrusion, coating or soaking, implemented in continued. In particular, the process of obtaining the wire electrically conductive, object of the invention, can consist, on an extruded and drawn core thread, scrolling in continuous, coating with a bonding agent, followed by dusting of the conductive particles intended to form the electrically conductive layer, then firing permanently fixing the conductive coating on the soul thread. The electrically conductive wire, finally obtained, can be easily wound on reels, without degradation of its electrical characteristics.

The core wire can, in one embodiment simple, have a round section. He can also have a star or serrated profile, which first advantage of increasing the adhesion surface of the coating conductor, and to improve the attachment of the latter on the soul thread. An added benefit of this configuration is to guarantee electrical continuity, even if the wire is scratched or worn out because the conductive particles at the bottom of the grooves, located between the "teeth" of the soul, are brought to protected from scratches or other surface aggressions thread.

Of course, in the case of an electric wire conductor applied to the creation of fences electric, the layer formed by particles electrically conductive forms, necessarily, the outer surface of the wire.

However, for other applications, the layer formed by electrically conductive particles can be, itself, covered with an insulating coating, which then forms the outer surface of the object wire present invention. A particular application, entering as part of this last embodiment of the invention is the production of a coaxial cable, in which an electrically conductive central wire is embedded in the insulating core, in synthetic material, surrounded by the conductive layer formed by the particles electrically conductive, this conductive layer being itself covered with an insulating coating. The layer formed of electrically conductive particles here replaces the traditional copper braid of cables coaxial, such as those used in the field of television, which leads to a simpler structure and to a more economical manufacture of this kind of cables electric.

Figure 1 est une vue en perspective d'un tronçon de fil électriquement conducteur conforme à la présente invention ;

Figure 2 est une vue en perspective d'un autre tronçon de fil électriquement conducteur, constituant une variante du précédent ;

Figure 3 est un schéma de principe d'un procédé, et de l'installation correspondante, pour la fabrication d'un fil électriquement conducteur selon l'invention ;

Figure 4 illustre une autre forme de réalisation de ce fil électriquement conducteur, constituant un câble coaxial.

The invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of examples, some embodiments of this electrically conductive wire, and illustrating its method of obtaining:

Figure 1 is a perspective view of an electrically conductive wire section according to the present invention;

Figure 2 is a perspective view of another section of electrically conductive wire, constituting a variant of the previous one;

Figure 3 is a block diagram of a process, and the corresponding installation, for the manufacture of an electrically conductive wire according to the invention;

Figure 4 illustrates another embodiment of this electrically conductive wire, constituting a coaxial cable.

Figure 1 shows a short section of a wire electrically conductive 1, which can in particular be a wire for electric fences, showing the section of this wire. The electrically conductive wire 1 is consists of a core wire 2, here of round section, which is electrically coated on all sides conductor 3, in particular forming the outer surface 4 of the wire 1.

The core wire 2 is a polyamide or other wire synthetic material, electrically insulating, of the type monofilament. The conductive coating 3 consists of fine particles of electrically conductive metal, preferably stainless, or carbon. This coating 3 forms a continuous electrically conductive layer, annular section, allowing current flow electric from one point to another of wire 1, whatever the remoteness of these points. The presence of this layer conductive on the surface 4 of the wire makes it suitable for constitute a wire for electric fence.

Figure 2 shows a short section of wire electrically conductive 1, constituting a variant of the previous. The core wire 2 made of insulating synthetic material here presents a star or serrated section, which increases the adhesion area of the conductive coating 3, and which guarantees the longitudinal continuity of the layer conductive. Indeed, the conductive material located at bottom of the longitudinal grooves of the core 2, formed between teeth 5 of this core, is preserved in case of local degradation of the outer surface 4 of the wire 1.

Figure 3 illustrates obtaining the wire electrically conductive 1 previously described, according to a particular process. The core thread 2 in material synthetic, previously manufactured by extrusion and stretching, scrolls continuously according to arrow 6. On the wire of core 2 is carried out, by a projection device or of appropriate application 7, coating with an agent adhesion 8. Next, a dusting device 9 projects the conductive particles onto the core wire 2 10, such as metal powder, intended to form the conductive coating 3. The assembly finally passes through an oven 11, which definitively fixes the coating conductor 3, formed of particles 10, on the core wire 2, so as to get the wire electrically at the outlet driver 1 corresponding to the description given more top with reference to Figures 1 and 2. This wire electrically conductive 1 can be finally wound around a take-up reel, not shown.

Figure 4 shows another wire electrically conductor 1 according to the invention, which constitutes a coaxial cable such as those used in the field of television. This wire 1 also comprises an insulating core 2, coated with a conductive coating 3. In the core 2, always made of insulating synthetic material, finds an electrically conductive central wire 12 embedded, such as a small section copper wire. The coating conductor 3, consisting of a powder of metal or carbon applied to the core 2, is itself covered by an insulating coating 13, of the sheath type, forming the outer surface of the coaxial cable. The coating conductor 3 of the core 2 constitutes here the conductor outer, annular section, coaxial cable and it replaces the traditionally included copper braid in coaxial cables.

We would not stray from the scope of the invention by modifying the material of the core thread, or its section, or using particles of any material suitable conductors of various particle sizes to form the conductive coating, or applying and fixing this conductive coating on the wire of soul by other methods than that described and illustrated. It should also be noted that the conductive coating does not form not necessarily a layer covering the core over any its circumference; ; we can consider a layer conductive covering only partially the core, in particular a conductive layer subdivided in the form of parallel, straight or helically wound bands around the soul, which can provide savings of conductive material (however by reducing correlatively the protection of the soul against ultraviolet rays). Furthermore, the uses of this electrically conductive wire is not limited to electric and coaxial fencing, and they include other electrical applications including low voltage, for which the conductive coating provides sufficient passage cross-section for current electric, without presenting any danger.

Claims (13)

1. An electrically conducting wire, characterized in that it comprises a core (2) of the monofilament type, made of synthetic material, which is coated with a coating (3) formed of electrically conducting particles, forming itself an electrically conducting longitudinally continuous layer.
2. The electrically conducting wire as claimed in claim 1, characterized in that its core (2) consists of a polyamide monofilament.
3. The electrically conducting wire as claimed in claim 1 or 2, characterized in that the conducting coating (3) is the result of an electrically conducting metal or carbon powder being applied to the external surface of the core wire (2).
4. The electrically conducting wire as claimed in any of claims 1 to 3, characterized in that the conducting coating (3) constitutes a continuous layer covering the entire circumference of the synthetic core (2).
5. The electrically conducting wire according to any of claims 1 to 3, characterized in that the conducting coating (3) is constituted by a layer that only partially covers the core (2), especially a conducting layer that is subdivided into parallel bands that are straight or are helically wound around the core (2).
6. The electrically conducting wire as claimed in any of claims 1 to 5, characterized in that its core (2) has a round cross section.
7. The electrically conducting wire as claimed in any of claims 1 to 5, characterized in that its core (2) has a star-shaped or striated profile.
8. The electrically conducting wire as claimed in any of claims 1 to 7, characterized in that the layer formed by the electrically conducting particles (3) forms the external surface (4) of said wire (1).
9. The electrically conducting wire as claimed in claim 8, characterized in that it constitutes a wire (1) for electric fences.
10. The electrically conducting wire as claimed in any of claims 1 to 7, characterized in that the layer formed by the electrically conducting particles (3) is itself covered by an insulating coating (13), which forms the external surface of the wire (1).
11. The electrically conducting wire as claimed in claim 10, characterized in that it constitutes a coaxial cable (1), wherein a central electrically conducting wire (12) is embedded in the synthetic core (2) surrounded by the conducting layer formed by the electrically conducting particles (3) the layer formed by the electrically conducting particles (3), this conducting layer being itself covered by an insulating coating (13).
12. The electrically conducting wire as claimed in any of claims 1 to 11, characterized in that the conducting coating (13) is applied to the synthetic core (2) by a coextrusion, coating or dipping process, performed continuously.
13. The electrically conducting wire as claimed in claim 12, characterized in that it is obtained by carrying out on an extruded and drawn core wire (2) in continuous motion: coating with an adhesive agent (8), followed by dusting with the particles (10) intended to form the electrically conducting layer (3), then baking to attach the conducting coating (3) permanently to the core wire (2).

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