EP1236819B1 - Electrically conductive fabric - Google Patents

Abstract

A fabric consists of a warp or weft containing groups of carbon filaments and groups of non-conducting filaments, the carbon filaments being in regularly-spaced strips (2) at set intervals (d). The weft or warp contains groups of metal and non-conducting filaments, the metal filaments being in strips (3) linking the carbon filaments in parallel and spaced regularly at intervals (D). A fabric consists of a warp or weft containing groups of carbon filaments and groups of non-conducting filaments, the carbon filaments being in regularly-spaced strips (2) at set intervals (d). The weft or warp contains groups of metal and non-conducting filaments, the metal filaments being in strips (3) linking the carbon filaments in parallel and spaced regular at intervals (D) that are at least five times greater than the intervals between the carbon filaments. Both warp and weft filaments are coated on both sides with a layer of insulating material. The metal filaments are selected from nickel, aluminum, stainless steel and gold-plated filaments.

Description

Technical area

The invention relates to the field of technical textiles, and more specifically to electrically conductive textiles. It finds multiple applications, and in particular in the realization of truck tarpaulins, flexible roofing elements or even furniture or interior design. It relates more particularly to a heating fabric incorporating metal and carbon son which allow heating by a "low voltage" power supply, and which is by design very easily configurable to any pattern of geometry, and to different heating surface powers.

Previous techniques

In a known manner, the electrically conductive textiles consist of a basic support fabric incorporating, in the form of a warp and / or weft, copper wires or more generally metallic wires. The presence of these threads gives the fabric structure a certain electrical conductivity by allowing multiple uses, and in particular to form heating tissues.

The object of the invention is to provide a fabric that has optimal and continuous electrical properties on the fabric surface.

Many solutions have already been proposed to integrate such a conductive thread inside a fabric.

So, in the document FR 2,340,016 or US 4,538,054 , a conductive fabric including among its weft son, conductive son electricity. These weft yarns are electrically connected in parallel by two conductive warp wires located on each side of the fabric.

It is conceivable that this kind of fabric has a number of disadvantages. Indeed, when it is desired to produce fabrics having a sufficient width, it is necessary to subject the weft son to a relatively large voltage, generally equal to the 220 volts AC grid voltage. The use of such a voltage raises problems of electrical safety, and in particular which concerns the risks of contact by persons. This high electrical voltage is also necessary in view of the poor connections existing between the electrode warp wires and the conductive weft wires.

Another example of such a fabric has also been described in the document FR 2,263,658 . In this case, the paralleling of the various conductors son is done by the use of a copper strip disposed in the edges of the fabric. The use of these strips has two major disadvantages. On the one hand, such copper strips are relatively rigid and prevent the fabric from becoming very simple. On the other hand, the connection between the strip and the conductors is relatively poor, and therefore requires the use of a high voltage, that is to say in practice the network voltage of 220 volts, inducing a very high current. weak more compatible with such quality of connection. The disadvantages of using a high voltage are the same as those indicated above.

In addition, the power dissipated per unit area, for a fabric of given dimensions, is solely a function of the applied voltage. In other words, it is not possible to adapt the power dissipated according to the desired application.

The object of the present invention is to provide a conductive fabric that can be used with "low voltage" type supply voltages, that is to say within the conventional range of 12 volts to 48 volts. Another objective is to allow a great modularity so as to ensure a dissipation of energy per unit area that is configurable by the user very easily.

Another objective is to provide a coated fabric whose coating does not disturb the connection properties between the conductors son.

Presentation of the invention

The invention therefore relates to a fabric which has properties of conduction of electricity.

Such a fabric is defined according to claim 1.

In other words, this fabric comprises, arranged in a regular manner, strips of carbon son which ensure a dissipation of energy when they are traversed by an electric current. These strips of carbon son are interconnected by strips of conductive son such as metal son, the son son strips serving as power supply son and current to the carbon son. These strips of supply son are much more spaced from one another than the carbon son strips.

By using two materials of distinctly different conductivity, that is to say carbon son having a resistivity much higher than that of metal son, most of the voltage drop is at the terminals of the carbon son, which ensure therefore a dissipation of energy very much higher than that which takes place in the transverse metal wires.

The weaving of the various son of the carbon son strip with the wires of the supply wire strip ensures a relatively large contact between these different wires, and therefore a connection which allows the passage of a large current, and therefore the use of the fabric in association with low voltage power supplies, of the type from 12 volts to 48 volts.

In addition, the distribution of metal son and carbon son over the entire surface of the fabric according to the invention gives the latter a matrix structure through which it is possible to supply voltage any length or width of fabric.

In other words, the supply son are sufficiently numerous over the entire width of the fabric to form two electrodes for any tissue cut.

Due to the weaving of the metal son and the carbon son, the pressure exerted on the contact zone between these different son is sufficient to withstand the pressure of the plastic material that is used during the coating operation of the fabric.

In practice, the metal wires used may be nickel-alloy wire, aluminum wire, stainless steel wire, or son covered with a layer of gold.

For example, it will be preferred to use nickel alloys for its good compatibility with the connection generally made with copper alloys. Given the very low number of metal supply son, the use of relatively expensive materials increases almost insensitively the cost of the fabric according to the invention. We will therefore favor the very good conductive qualities of some relatively expensive metals.

Moreover, the non-conductive wires used between the metal wires may advantageously be polyester wires, used for their good mechanical behavior.

Other metals can also be used when their resistivity is sufficiently low, compared with that of the carbon heating son, and taking into account the ratio between the distances d and D separating the different strips of carbon son and son d metal feed.

In a particular form, the coating layers, and for example coating, covering the two faces of the fabric may be different.

In this way, it ensures a dissipation of energy that is different from one side to the other of the fabric, which allows to direct the heat flow in a preferred direction. In practice, coating layers are chosen which have different thermal properties, for example by using fillers in different proportions from one face to the other.

Advantageously, in practice, the distance d between the strips of carbon son may be between 1 and 10 centimeters, the distance separating the strips of metal son then being between 20 centimeters and 2 meters.

With these dimensions given as indicative and non-limiting, it is possible to cut the fabric retaining the possibility of a feed regardless of the general shape of the cut, when it is greater than the dimension D between the stripes of metal threads.

In practice, power can be obtained by connecting different power supply strips alternately to one of the two terminals of the power supply.

According to another characteristic of the invention, the fabric may have on its edges, and at the ends of the strips of metal son, areas in which the coating layers are removed. In this way, by making a cut perpendicular to the strips of metal son, at the level of the latter, it is sufficient to extract the coating layers by sliding around the metal son by pulling outwardly of the fabric. This is done in the same way that is denuded a sheathed wire denuding the end zone of the strip of the wire.

It follows that all the metal son thus stripped can be collected and then put in place in power terminals arranged on the edges of the fabric.

These supply terminals can be arranged at the end of all or part of the metal terminals, depending on the supply voltage that it is desired to apply to the fabric.

Thus, by varying the number of wire strips present between two power supply terminals, the power dissipated per unit area is varied, which makes it possible to adapt the fabric to different applications.

Brief description of the figures

• La figure 1 est une vue schématique d'un tissu conforme à l'invention.
• La figure 2 est une vue en coupe de détail illustrant le tissage des fils de carbone et des fils métalliques.
• La figure 3 est une vue en perspective sommaire d'une lisière du tissu conforme à l'invention, pendant la réalisation d'une connexion latérale.
• La figure 4 illustre une étape ultérieure de celle de la figure 3.
• La figure 5 est une vue schématique illustrant les différentes possibilités d'alimentation d'un dispositif conforme à l'invention.

The manner of carrying out the invention as well as the advantages which result therefrom will emerge clearly from the description of the embodiment which follows, given by way of non-limiting example, with reference to the appended figures in which:

• Figure 1 is a schematic view of a fabric according to the invention.
• Figure 2 is a detail sectional view illustrating the weaving of carbon son and wire.
• Figure 3 is a summary perspective view of a selvedge of the fabric according to the invention, during the realization of a lateral connection.
• Figure 4 illustrates a step subsequent to that of Figure 3.
• Figure 5 is a schematic view illustrating the different power supply possibilities of a device according to the invention.

Way of realizing the invention

As already mentioned, the invention relates to a heating textile which is made by weaving, and which incorporates two types of different conductive son in these warp and weft directions.

Thus, and as illustrated in the example of Figure 1, the fabric (1) comprises strips (2) of carbon son which are spaced a distance d. This fabric (1) also comprises strips (3) of metal son.

In the example illustrated, the carbon threads have a title of 200 tex and comprise 200 fibers per son. Each band (2) comprises five carbon threads of this type. The strips (2) of carbon threads are spaced apart by a distance d of 5 centimeters.

In the example of Figure 1, the metal son used are the pure nickel son of twenty hundredths of a millimeter in diameter. Each strip (3) of metal son comprises ten son of nickel, which represents a bandwidth of the order of one centimeter.

The strips (3) of metal son are distant by a distance D of about one meter.

Given that the resistivity of nickel is about a hundred times lower than that of carbon, the voltage drop measured along the supply son of a strip (3) is negligible with regard to the measured voltage drop along copper wires between two successive strips (3).

It is this last voltage drop that causes the heating of the copper wires and the energy dissipation sought.

The yarns (4) used for the rest of the fabric are non-conductive yarns, for example conventional high tenacity polyester yarns of 1100 dtex, 200 strands.

Of course, the values and materials given above are only by way of example, and the invention covers multiple variants that depart from it.

The weaving of the wires (13, 14) with carbon threads (12) as illustrated in Figure 2, provides an advantage with respect to the contact surface between these different threads. Indeed, the contact zone between the carbon son (12) and the metal son (13) extends over a portion of the circumference of the carbon son (13), typically greater than a quarter of this circumference. Carbon yarns that are softer than metal wires tend to crush, which dramatically increases the contact area.

This large contact area allows the passage of a relatively high current, such as those used for low voltage supplies of type 12 to 48 volts.

In Figure 2, there is also the presence of the coating layer (15, 16) which covers both sides of the fabric, thus preventing any risk of contact with areas under tension. In the form shown, the coating layers (15, 16) are identical and made for example of PVC. However, as already mentioned, these layers (15, 16) may be different so as to influence the direction of the heat flux released by the carbon son (12).

For example, when the textile according to the invention is used as the upper cover of a building, and that it is intended to ensure a controlled melting snow, we will favor the heat flow to the upper face fabric. In this case, the coating layer (15) on the upper face of the fabric has a better thermal conductivity than the layer (16) on the underside.

Similarly, the coating used may be such that its heat conduction properties vary on the very surface of one side of the fabric. Thus, by modulating this thermal conductivity, it is possible to standardize the heat flux emitted between the zones comprising the carbon wires, and the spaces situated between these carbon son strips.

Another feature of the invention relates to the ease with which the fabric according to the invention can be connected to the power supply. Figures 3 and 4 illustrate the manipulations necessary to ensure the connection of the fabric to a power source.

Thus, the fabric (1) has on its edge (5) different weft son that are visible through the coating layer (15). Among these visible yarns, non-conductive polyester yarns (6) and metallic yarns (13) are identified. These metal wires (13) are part of a strip (3) of conductive wires. After making a notch of the fabric in the planes (20, 21) parallel to the weft, was cut the polyester warp son (4) located in this region.

Subsequently, a slight notch (22) is made parallel to the warp threads to delimit the area which will then be extracted. This notch (22) can be achieved by a suitable tool or even not be physically materialized, but simply result from the traction that will be performed by the operator.

Subsequently, the operator exerts traction on the area defined by the cutouts (20, 21, 22). This zone (25) slides on the metal wires (13), which is then extracted as in FIG. 4. This zone contains the portions of polyester threads (4) which have been cut beforehand during the making of the cuts (20, 21). The various metal son (13) are then apparent at the edge of the fabric, and it is sufficient for the operator to gather them to put them in place in the appropriate connector. The connection of the strip (3) of metal wires (13) is thus ensured.

Of course, the operator chooses according to the configuration of the fabric and the supply voltage strips (3) which must be so denuded.

Thus, different power configurations can be used.

Thus, as illustrated in Figure Sa, the power source (26) can see its upper terminal connected to the terminals of the metal wires (3a, 3c, 3e), while its lower terminal is connected to the strips (3b, 3d). . In other words, all segments of carbon son located between two strips (3) of metal son are subjected to the supply voltage of the source (26).

In the other configuration illustrated in Figure 5b, the power source (27) has its upper terminal connected to the bands (3a, 3e) of the fabric, while its lower terminal is connected to the web (3c) of the fabric. In this case, and at constant supply voltage, the carbon wire segments are subjected to a potential difference equal to half that of the previous configuration.

It follows that the heat generated by the surface unit is equal to a quarter of that dissipated in the case of the configuration of the power source (26).

The same logic can be declined with the configuration of the power source (28) illustrated in Figure 5c. In this case, the power source (28) is connected by its positive terminal to the band (3a) and its negative terminal to the band (3e). Equivalent source, the voltage imposed on the carbon son is worth one quarter of that of the configuration (26), which results in a power dissipated sixteen times lower.

Of course, the wiring diagram of the various metal strips (3) can be adapted according to the desired dissipation power, by determining the length of the carbon wires required, and therefore the multiple of the distance D to obtain the dissipation of the desired power.

This wiring can also be variable inside the fabric itself, to concentrate the dissipation of energy in certain particular areas.

In the same way, this wiring can be adapted according to the nominal voltage of the sources (26-28) used.

Thus, for example, for a power to be dissipated of the order of 100 watts per square meter, a supply voltage of 12 volts may be sufficient. These are applications allowing a slight warming of the fabric to eliminate the condensation present on it when used to make marquee tents or other similar constructions.

For a wiring diagram, a 24-volt power supply will quadruple the power dissipated per unit area. Thus, with a dissipation of 400 watts per square meter, the fabric can be used to make roofs or hangings superior to withstand the snow. In this case, the heating will ensure a slight melting of the snow. This merger will be controlled, so that the accumulation of water during the snowmelt will be avoided, thanks to a control of the areas in which the snow will melt first.

When the same configuration scheme is used with a 48-volt power supply, corresponding to a dissipation of 1,600 watts per square meter, the fabric can then be used for heating applications, for example to form partitions or heating ceilings.

• ❖ la possibilité d'être alimenté de façon tout à fait sûre par des alimentations basses tension, du type 12 à 48 volts ;
• ❖ une très grande modularité du fait de sa structure matricielle, qui permet d'obtenir les propriétés recherchées quelle que soit la forme des découpes du tissu ;
• ❖ une grande facilité pour réaliser la connectique aux sources d'alimentation électrique.

It follows from the foregoing that the fabric according to the invention has multiple advantages and in particular:

• ❖ the possibility of being supplied with complete safety by low voltage power supplies, type 12 to 48 volts;
• ❖ a very great modularity due to its matrix structure, which makes it possible to obtain the desired properties irrespective of the shape of the cuts of the fabric;
• ❖ a great facility to realize the connection to the sources of electrical power.

Industrial applications

The fabric according to the invention has multiple applications thanks on the one hand to its matrix structure, on the other hand to its great ease of connection.

Thus, this fabric can be used for multiple heating applications, outer walls of building, and partition-type or other interior walls. It can also be used for heating functions in all kinds of articles suitable for being coated with a textile. It may also be accessories used in the home such as blinds.

Thanks to its excellent electrical properties, this fabric can also be used for anti-static applications, particularly in areas where it is necessary to carry out dust extractions such as mining industries, or automobile or railway tunnels, or still well in the electronics industry.

It can also be used to equip buildings to give them Faraday cage properties.

Claims (8)

1. Fabric (1) possessing electrical conduction properties and comprising:

   - in the warp or weft directions respectively, groups of carbon yarns (12) and groups of electrically non-conducting yarns (4), said groups of carbon yarns forming bands (2) regularly spaced apart by a distance d;

   - in the weft or warp directions respectively, groups of metal wires (13); and

   - an insulating cover layer (15, 16) covering each face of the fabric,

   characterized in that it also includes, in the weft and warp directions respectively, groups of electrically non-conducting yarns, said groups of metal wires forming bands (3) electrically connecting in parallel the bands (2) of carbon yarns together, the bands (3) of metal wires being regularly spaced by a distance D at least five times greater than the distance d, and in that the dimension of the fabric in the weft or warp directions respectively is greater than the distance D separating the bands of metal wires (13), so that the distribution of the metal wires (13) and of the carbon yarns (12) over the entire surface of the fabric gives the latter a matrix structure, whereby it is possible to supply the fabric with voltage.
2. Fabric according to Claim 1, characterized in that the metal wires (13) are chosen from nickel wires, aluminium wires, stainless steel wires and wires coated with a layer of gold.
3. Fabric according to Claim 1, characterized in that the electrically non-conducting yarns (14) are polyester yarns.
4. Fabric according to Claim 1, characterized in that the insulating cover layers (15, 16) are layers obtained by coating.
5. Fabric according to Claim 1, characterized in that the insulating cover layers (15, 16) are different on the two faces of the fabric.
6. Fabric according to Claim 1, characterized in that the distance d separating the bands (2) of carbon yarns is between 1 and 10 centimetres and in that the distance D separating the bands (3) of metal wires is between 20 centimetres and 2 metres.
7. Fabric according to Claim 1, characterized in that it has on its selvedges (5), and at the ends of the bands (3) of metal wires, regions (25) in which the coating layers (15, 16) have been removed.
8. Fabric according to Claim 1, characterized in that it furthermore includes power supply terminals placed on its selvedges, at the end of certain groups of metal wires.

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