SPACER FABRIC, SPACER FABRIC SECTION AND HEATABLE COVERING ELEMENT

Abstract

A spacer fabric has a first flat layer of knitted fabric formed with conductive threads, a second flat layer of knitted fabric and spacer threads connecting the first and second layers of knitted fabric. The conductive threads have an electrically conductive coating and are arranged adjacent to one another over an entire surface in the first layer or in conductive strips extending along a direction of production, and are connected to one another in direct, electrical contact. The conductive threads preferably are formed from a plastic multifilament yarn provided with a coating and have a fineness of less than 250 dtex. The conductive threads in the first layer of knitted fabric form loops with a stitching over at least two wales. The portion of the conductive coating is less than 50% by weight of the conductive threads.

Claims

1. A spacer fabric, comprising: a first flat layer of knitted fabric formed with conductive threads; a second flat layer of knitted fabric; and spacer threads connecting the first layer and the second layer of knitted fabric; wherein the conductive threads comprise an electrically conductive coating, are arranged adjacent to one another over an entire surface in the first layer of knitted fabric or are arranged in conductive strips extending along a direction of production (P) of the first layer of the knitted fabric and are connected to one another in direct, electrical contact; wherein the conductive threads are formed from a plastic multifilament yarn provided with the conductive coating, have a fineness of less than 250 dtex and are knitted in the first layer of knitted fabric with a stitching over at least two wales; wherein the conductive coating comprises a portion of the conductive threads that is less than 50% by weight; and wherein individual filaments of the plastic multifilament yarn are each enclosed in the conductive coating and are movable with respect to one another.

2. The spacer fabric according to claim 1, wherein the conductive coating consists of metal.

3. The spacer fabric according to claim 1, wherein the metal comprises silver.

4. The spacer fabric according to claim 1, wherein the filaments of the plastic multifilament yarn consist of a material selected from the group consisting of polyamide, polyester and polypropylene.

5. The spacer fabric according to claim 1, wherein at least ten conductive threads are provided for forming the conductive strips extending in the direction of production (P).

6. The spacer fabric according to claim 1, wherein the conductive threads are disposed over the entire surface in the first layer of knitted fabric; and wherein the first layer of knitted fabric is formed exclusively of the conductive threads.

7. The spacer fabric according to claim 1, wherein the spacer threads are formed from a monofilament yarn having a filament diameter between 55 m and 80 m.

8. A spacer fabric section formed from a spacer fabric according to claim 1.

9. The spacer fabric section according to claim 8, wherein both the first layer and the second layer of knitted fabric and the interposed spacer threads have been removed at at least one opening in the spacer fabric section, and wherein the conductive threads in the first layer of knitted fabric have therefore been interrupted in said at least one opening.

10. The spacer fabric section according to claim 7, wherein spaced-apart electrical contacts are directly connected to the conductive threads of the first layer of knitted fabric extending on the contact surface, via punctiform contact areas.

11. The spacer fabric section according to claim 10, wherein multiple openings are provided and are disposed in such a way that, when current is applied to the electrical contacts, a more even two-dimensional current distribution results than would be the case with a spacer fabric section having no openings but an otherwise identical design.

11. A heatable covering element comprising a spacer fabric section according to claim 8 and a cover layer disposed on the spacer fabric section.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0055] The invention is explained in greater detail in the following with reference to a drawing. In the drawings:

[0056] FIG. 1 shows the design of the spacer fabric;

[0057] FIG. 2 shows one alternative embodiment of the spacer fabric according to FIG. 1;

[0058] FIG. 3 shows a section through a conductive thread of a first layer of knitted fabric of the spacer fabric, according to the inventive embodiments of FIG. 1 and FIG. 2;

[0059] FIG. 4 shows a strip-shaped spacer fabric section having an opening;

[0060] FIG. 5 shows a spacer fabric section having multiple openings and spaced-apart electrical contacts;

[0061] FIG. 6 shows an alternative embodiment of the spacer fabric section according to FIG. 5; and

[0062] FIG. 7 shows a variation of the spacer fabric section of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0063] The following is a detailed description of example embodiments of the invention depicted in the accompanying drawing. The example embodiments are presented in such detail as to clearly communicate the invention and are designed to make such embodiments obvious to a person of ordinary skill in the art. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention, as defined by the appended claims.

[0064] FIG. 1 shows the basic design of a spacer fabric according to the invention, comprising a first flat layer of knitted fabric 1, a second flat layer of knitted fabric 2, and spacer threads 3 connecting the layers of knitted fabric 1, 2. The first layer of knitted fabric 1 comprises conductive threads 4, which are further described in the following in association with FIG. 3.

[0065] According to FIG. 1, the entire first layer of knitted fabric 1 is formed from conductive threads 4, wherein, according to the detailed sectional view from FIG. 1, the electrically conductive threads 4 are arranged in a tricot stitch, and therefore the conductive threads 4 in the first layer of knitted fabric 1 form loops over two wales. Due to the formation of loops, adjacent conductive threads 4 are closely intertwined and are electrically connected to one another by means of a direct electrical contact on the surface of the conductive threads 4.

[0066] The spacer fabrics according to FIG. 1 and FIG. 2 differ in that, according to FIG. 2, the conductive threads 4 are disposed only in conductive strips 5, and not in the strips 5 that are shown separating the conductive strips 5. Different threads may be used in the strips 5, wherein the stitching pattern nevertheless remains the same as in the conductive strips 5. Preferably, at least ten threads extending in a direction of production P are provided for forming the conductive strips 5. Groups of conductive threads 4 therefore alternate with groups of non-conductive thread in the transverse direction Q.

[0067] FIG. 3 shows a detailed view of a cross-section of the conductive threads 4 provided within the scope of the invention. Accordingly, the conductive threads 4 comprise a plastic multifilament yarn 6 provided with a coating 7, wherein the plastic multifilament yarn usually comprises between 3 and 40 filaments, for example, 24 filaments, or any other number of filaments between 3 and 40, without deviating from the scope and spirit of the invention. The portion of the conductive coating 7 relative to the total weight of the conductive threads is less than 50% by weight, in particular. less than 15% by weight, for example, between 1% by weight and 5% by weight. The conductive coating 7 can be either metallic or non-metallic. Reference is made in the following to a metallic coating 7 in the form of silver, as a preferred embodiment, merely by way of example.

[0068] Due to the core-casing structure of the plastic multifilament yarn 6 provided with the coating 7, the conductive threads 4 are moveable to a particular extent, wherein the metallic coating 7 made from silver is distinguished by a low electrical resistance, and therefore the metallic coating 7 is relatively thin, i.e., in view of a typical geometry and the density of metallic coatings, the coating thickness always is less than 15% of the radius of the core, and preferably less than 5% of the radius of the core. Surprisingly, the metallic coating 7 is not destroyed during the formation of loops of the filaments, which is precisely why the relatively soft properties of silver are advantageous. The thin metallic coating 7 also makes it possible to stiffen the filaments of the plastic multifilament yarn 6 only to a slight extent.

[0069] FIG. 4 shows a spacer fabric section, which is provided with an opening 8 for test purposes. The spacer fabric section can be formed from a spacer fabric according to FIG. 1, wherein a similar behavior results, however, when a conductive strip 5 having an opening 8 is provided in a spacer fabric according to FIG. 2.

[0070] In FIG. 4, the spacer fabric section is provided, at its ends with electrical contacts 9 in the form of simple connection terminals. Since the spacer fabric on the first layer of knitted fabric 1 is two-dimensionally conductive, a contacting via connecting leads or the like can be dispensed with, depending on the application. A linear contacting also can be advantageous in terms of an even, reliable current distribution.

[0071] Lines corresponding to a certain temperature are shown in FIG. 4 for illustrating the heating. The temperature profile is therefore depicted in the manner of an elevation map or a topographical map.

[0072] Initially, it is apparent that the temperature decreases toward the edges of the spacer fabric section due to the increased cooling as a result of heat dissipation to the surroundings and due to the reduced current flow. In addition, a largely even temperature profile results over a large portion of the spacer fabric section, however.

[0073] At the opening 8, the conductive threads 4 have been interrupted, and therefore, the current flow must take place around the opening 8. Consequently, a greater current and, therefore, increased heat output result there. According to the invention, however, due to the two-dimensionally conductive properties of the spacer fabric, openings 8 can be formed in the material provided the openings 8 are not too large and the segments remaining on the sides of the openings 8 have sufficient conductivity. The openings 8 can be provided, for example, for purely practical reasons, in order to provide passage openings or to guide mechanical connecting elements therethrough. Suitable openings 8 can be necessary or expedient, for example, in order to use the spacer fabric section as a heatable covering element having a cover layer.

[0074] FIG. 5 shows that virtually any type of opening 8 can be provided in a spacer fabric section, wherein such a spacer fabric section is expediently provided with electrical contacts 9 on opposite ends. In addition to connection terminals, electrical contacts also can be easily bonded onto the first layer of knitted fabric 1, in order to contact the conductive threads 4 extending there, at a point.

[0075] FIG. 6 shows that, due to the position of the openings 8, the current distribution and, therefore, the heating of the spacer fabric section can be influenced and adapted to the particular requirements. For this purpose, instead of continuous openings 8, it is also possible to simply provide incisions 8 in the first layer of knitted fabric 1, which separate the conductive threads 4 in sections. The FIG. 7 embodiment depicts the incisions 8 rather than the continuous openings 8, depicted in FIG. 6. Due to the described measures, a very even heating can take place, depending on the requirements, or individual regions can be heated to a great extent, to a lesser extent, or not at all, depending on the requirements.

[0076] Provided the conductive threads 4 are not interrupted, the thermal conduction within the material also contributes to an even thermal distribution, wherein silver, specifically, as a preferred metallic coating 7, has particularly good thermal conductivity.

[0077] As will be evident to persons skilled in the art, the foregoing detailed description and figures are presented as examples of the invention, and that variations are contemplated that do not depart from the fair scope of the teachings and descriptions set forth in this disclosure. The foregoing is not intended to limit what has been invented, except to the extent that the following claims so limit that.