FR2821366A1 - Fabric with electrical conducting properties has interwoven groups of metal, carbon and non-conducting filaments in insulation layer - 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

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FABRIC HAVING ELECTRICAL CONDUCTION PROPERTIES Domaine Tehnique
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 production of truck tarpaulins, flexible roofing elements or even furnishing or interior fittings. It relates more particularly to a heating fabric incorporating metallic and carbon wires which allow heating by a low voltage power supply, and which is by construction very easily configurable to any geometry pattern, and to different surface powers of heating.

Previous techniques
In known manner, electrically conductive textiles consist of an elementary support fabric incorporating in warp and / or in weft copper wires or more generally metal wires. The presence of these threads gives the fabric structure a certain electrical conductivity by allowing multiple uses, and in particular for constituting heating fabrics.

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

 Many solutions have already been proposed for integrating such a conductive wire inside a fabric.

 Thus, in the document FR 2 340 016, a conductive fabric has been described including among its weft yarns, electrically conductive yarns. These weft threads are electrically connected in parallel by two conductive warp threads located on each side of the fabric.

 It is understood that this kind of fabric has a number of drawbacks.

Indeed, when it is desired to produce fabrics having a sufficient width, it is necessary to subject the weft threads to a relatively large voltage, generally equal to the 220 volts AC voltage. The use of such a voltage poses electrical safety problems, and in particular in that

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 which concerns the risks of contact by people. This high electrical voltage is also necessary taking into account the mediocrity of the connections existing between the chain wires forming an electrode, 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 parallel connection of the various conducting wires is done by the use of a copper strip placed in the edges of the fabric. .

The use of these strips has two major drawbacks. On the one hand, such copper strips are relatively rigid and prevent the fabric from being shaped very simply. On the other hand, the connection between the strip and the conductive wires is relatively poor, and therefore requires the use of a high voltage, that is to say in practice the network voltage 220 volts, inducing a very low current more compatible with such a connection quality. 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 only a function of the applied voltage. In other words, it is not possible to adapt the dissipated power according to the desired application.

 The objective of the present invention is to provide a conductive fabric which can be used with supply voltages of the low voltage type, that is to say included in the conventional range going from 12 volts to 48 volts. Another objective is to allow a great modularity so as to ensure a dissipation of energy per unit of surface which 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 conductive wires.

Statement of the invention
The invention therefore relates to a fabric which has electrical conduction properties.

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Such a fabric is characterized in that it comprises: in the warp or weft direction, groups of carbon threads and groups of non-electrically conductive threads, said groups of carbon threads forming bands regularly spaced from a distance d; in the weft or warp direction, groups of metallic wires and groups of non-electrically conductive wires, said groups of metallic wires forming stripes electrically connecting in parallel the groups of carbon threads, the stripes of metallic threads being regularly spaced by a distance D at least five times greater than the distance d; ee a layer of insulating coating covering each side of the fabric.

 In other words, this fabric comprises, arranged in a regular manner, strips of carbon threads which ensure energy dissipation when they are traversed by an electric current. These strips of carbon threads are connected together by strips of conductive threads such as metallic threads, the strips of metallic threads serving as supply and current leads for the carbon threads. These strips of power wires are clearly spaced apart from each other than the strips of carbon wires.

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

 The weaving of the different threads of the strip of carbon threads with the metallic threads of the strip of supply threads ensures a relatively large contact between these different threads, and therefore a connection which allows the passage of a large current, and therefore the use of fabric in combination with low voltage power supplies, of the 12 volt to 48 volt type.

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In addition, the distribution of the metallic threads and the carbon threads over the entire surface of the fabric gives the latter a matrix structure thanks to which it is possible to supply any length or width of fabric with tension, as soon as this width or length is greater than the distance D separating the strips of metal wires.

 In other words, the supply wires are numerous enough over the entire width of the fabric to constitute two electrodes for any cut of fabric.

 Due to the weaving of the metallic threads and the carbon threads, the pressure exerted on the contact zone between these different threads is sufficient to resist the pressure of the plastic material which is used during the coating operation of the fabric.

 In practice, the metal wires used can be wires based on a nickel alloy, aluminum wires, stainless steel wires, or wires covered with a layer of gold.

 It will be preferred, for example, to use nickel alloys for its good compatibility with the connection generally carried out with copper alloys. In view of the very small number of metallic supply wires, the use of relatively expensive materials increases the cost price of the fabric according to the invention almost insensitively. We therefore favor the very good conductive qualities of certain relatively expensive metals.

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

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

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

 In this way, energy is dissipated which is different from one face to the other of the fabric, which makes it possible to orient 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 separating the strips of carbon wires can be between 1 and 10 centimeters, the distance separating the strips of metal wires then being between 20 centimeters and 2 meters.

 Thanks to these dimensions given by way of non-limiting indication, it is possible to cut the fabric while preserving the possibility of feeding whatever the general shape of the cut, as soon as it is greater than the dimension D separating the stripes of metallic wires.

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

 According to another characteristic of the invention, the fabric may have on its selvedges, and at the location of the ends of the strips of metal son, areas in which the coating layers are eliminated. In this way, by making a cut perpendicular to the strips of metal wires, at the level of the latter, it suffices to extract the coating layers by sliding them around the metal wires by pulling them towards the outside of the fabric. This is done in the same way as stripping a sheathed metal wire by stripping the end zone of the strip of metal wire.

 It follows that all of the metal wires thus stripped can be brought together to then be placed in supply terminals placed on the edges of the fabric.

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

 Thus, by varying the number of strips of metal wires present between two electrical 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
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 nonlimiting example, in support of 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 threads and metallic threads.

 Figure 3 is a summary perspective view of an edge of the fabric according to the invention, during the production of a lateral connection.

 FIG. 4 illustrates a subsequent step from that of FIG. 3.

 Figure 5 is a schematic view illustrating the different possibilities of supplying a device according to the invention.

Way of realizing the invention
As already mentioned, the invention relates to a heating textile which is produced by weaving, and which incorporates two different types of conducting threads in these warp and weft directions.

 Thus, and as illustrated in the example of FIG. 1, the fabric (1) comprises strips (2) of carbon threads which are spaced apart by a distance d. This fabric (1) also comprises strips (3) of metallic threads.

 In the example illustrated, the carbon threads have a count of 200 tex and comprise 200 fibers per thread. Each strip (2) comprises five carbon threads of this type. The strips (2) of carbon threads are spaced at a distance d of 5 centimeters.

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 In an alternative embodiment, the carbon wires can be replaced by wires having similar electrical properties, that is to say a resistivity greater than the supply wires. Mention may be made, for example, of wires produced from metallic fibers, with a diameter of the order of a micrometer.

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

 The strips (3) of metal wires are spaced apart by a distance D equal to about one meter.

 Considering the fact that the resistivity of nickel is about a hundred times lower than that of carbon, the voltage drop measured along the supply wires of a strip (3) is negligible compared to the voltage drop measured along copper wires between two successive bands (3).

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

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

 Of course, the values and materials given above are given only by way of example, and the invention covers multiple variant embodiments which deviate from them.

 The weaving of the metallic wires (13,14) with carbon wires (12) as illustrated in FIG. 2, provides an advantage as regards the contact surface between these different wires. In fact, the contact zone between the carbon wires (12) and the metal wires (13) extends over a part of the circumference of the carbon wires (13), typically greater than a quarter of this circumference. Carbon wires, which are more flexible than metal wires, tend to crush, which considerably increases the contact surface.

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

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

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

 Likewise, the coating used can be such that its heat conduction properties vary on the very surface of one face of the fabric. Thus, by modulating this thermal conductivity, it is possible to standardize the flow of heat emitted between the zones comprising the carbon wires, and the spaces located between these carbon wire bands.

 Another characteristic 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 tissue to a power source.

 Thus, the fabric (1) has on its selvedge (5) different weft threads which are apparent through the coating layer (15). Among these visible threads, the non-conductive polyester threads (6) and the metallic threads (13) are identified. These metal wires (13) are part of a strip (3) of conductive wires. After cutting the fabric along the planes (20,21) parallel to the weft, the polyester warp threads (4) located in this region were cut.

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We then proceed to a slight notch (22) parallel to the warp threads to delimit the area which will then be extracted. This notch (22) can be produced by an appropriate tool or even not be physically materialized, but simply result from the traction which will be carried out by the operator.

 Thereafter, the operator exerts a traction on the zone delimited 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 wires (4) which were previously cut during the making of the notches (20, 21). The different metal wires (13) are then visible at the edge of the fabric, and the operator just has 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 the strips (3) which must be thus stripped.

 Thus, different power configurations can be used.

 Thus, as illustrated in FIG. 5a, the power source (26) can have 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 the segments of carbon wires situated between two strips (3) of metallic wires are subjected to the supply voltage of the source (26).

 In the other configuration illustrated in FIG. Sb, the power source (27) has its upper terminal connected to the strips (3a, 3e) of the fabric, while its lower terminal is connected to the strip (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 released by the surface unit is equal to a quarter of that which is dissipated in the case of the configuration of the power source (26).

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

 Of course, the wiring diagram of the different metal strips (3) can be adapted as a function of 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, 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, by way of 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 then applications allowing a slight heating of the fabric in order to eliminate the condensation present on it when it is used to make marquee tents or other similar constructions.

 For a wiring diagram, a 24 volt 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 upper drapes capable of supporting snow. In this case, the heating will ensure a slight melting of the snow. This fusion will be controlled, so that water accumulations will be avoided during the melting of snow, thanks to a control of the zones in which the snow will melt first.

 When the same configuration diagram is used with a 48-volt power source, therefore corresponds to a dissipation of 1600 watts per square meter, the fabric can then be used for heating applications, for example to form partitions or heated ceilings.

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 It appears from the above that the fabric according to the invention has multiple advantages and in particular: the possibility of being supplied in a completely safe manner by low voltage power supplies, of the 12 to 48 volt type; . :. a very high modularity due to its matrix structure, which makes it possible to obtain the desired properties whatever the shape of the cutouts of the fabric; great ease in making the connections to the power sources.

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, in exterior walls of buildings, as well as in interior walls of the partition type or the like. It can also be used for heating functions in all kinds of articles suitable for being coated with a textile. It can also be accessories used in the home such as blinds.

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

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

Claims (8)

CLAIMS 1 / Fabric (1) having electrical conduction properties, characterized in that it comprises: - in the warp or weft direction, groups of carbon threads (12) and groups of threads (4) not electrically conductive, said groups of carbon wires forming bands (2) regularly spaced apart by a distance d; - in the weft or warp direction, groups of metallic wires (13) and groups of non-electrically conductive wires, said groups of metallic wires forming bands (3) electrically connecting the bands (2) of wires in parallel carbon between them, the strips (3) of metal wires being regularly spaced by a distance D at least five times greater than the distance d; - an insulating coating layer (15,16) covering each side of the fabric. 2 / fabric according to claim 1, characterized in that the metal son (13) are chosen from nickel son, aluminum son, stainless steel son and son covered with a layer of gold. 3 / Fabric according to claim 1, characterized in that the son (14) non-conductive of electricity are polyester son. 4 / Fabric according to claim 1, characterized in that the layers of insulating coating (15,16) are layers obtained by coating.

5 / fabric according to claim 1, characterized in that the layers of insulating coating (15,16) are different on the two sides of the fabric. 6 / fabric according to claim 1, characterized in that the distance d separating the strips (2) of carbon threads is between 1 and 10 centimeters, and in that the distance D separating the strips (3) of metallic threads is between 20 centimeters and 2 meters. 7 / Fabric according to claim 1, characterized in that it has on its selvedges (5), and at the location of the ends of the strips (3) of metal son, areas (25) in which the coating layers (15,16) are eliminated. <Desc / Clms Page number 13> 8 / fabric according to claim 1, characterized in that it further comprises supply terminals arranged on its edges, at the end of certain groups of metal son. Depositor: WEAVING AND COATING SERGE FERRARI SA Agent: Cabinet LAURENT ET CHARRAS