EP2000005A2 - Contacting system, heating element and production of a contacting system and heating element - Google Patents

Abstract

The contacting system has heating elements with a strip like surface shape and a structured layered combination with a carrier material (2), a metallic conductor (3) and an electrically conductive layer (1). The carrier material has a plastic manufactured foil. The metallic conductor has a wire mesh and/or a wire cord. The electrically conductive layer (1) has one or more flexible electrically conductive foils, which is based on a polymer. Independent claims are also included for the following: (1) a heating element, has a heating layer with multiple electrically conductive foils (2) a method for producing a contacting system, involves making of a carrier material, a metallic conductor and an electrically conductive layer.

Description

 CONTACT SYSTEM, HEATING ELEMENT AND MANUFACTURING OF A CONTACT SYSTEM AND HEATING ELEMENT

The present invention relates to a contacting system, in particular for the electrical contacting of substantially flat heating elements. Furthermore, the invention relates to a corresponding heating element. Finally, the invention relates in each case to a method for producing a contacting system and for producing a heating element.

Already known are heating elements based on plastics and suitable electrically conductive particles (carbon blacks, graphites, carbon fibers, metals, metal oxides or mixtures of these components).

Also known are plastics which themselves have electrical conductivity (intrinsically conductive polymers).

In order to use these materials for the production of flexible heating elements, a contact with at least two current-carrying wires is necessary. The basically known possibilities for the application of these wires are:

a) Sew on:

This method represents a quick and uncomplicated way of contacting. However, the problem is that the wire does not have an optimal contact with an electrically conductive foil to be provided at all points, so that a significant contact resistance occurs. This contact resistance leads to a decrease in power of the heating element.

Furthermore, at high current densities, points with higher power consumption can form at the points with good contact to the film ("hot spots") .These "hot spots" can possibly lead to the destruction of the heating element.

As an additional problem, the contact with the film depending on the mechanical load of the heating element (bending, bending o. Ä.) Vary, a non-reproducible or unpredictable change in the total heating power is the result. Due to different coefficients of thermal expansion of the film material and the wires used in continuous operation also changes in the contact can occur, which may also be irreversible.

b) sticking on:

By gluing the contact wires with suitable electrically conductive adhesives (conductive paints), a cohesive and permanent contact with the conductive surface of a heating element can be produced. The adhesives used here are polymers filled with conductive solids. These may include carbon blacks or metal particles (preferably silver).

The problems of this technical solution are initially due to the fact that the contact wire is completely surrounded by the adhesive, whereby a large part of the flexibility is lost.

Another problem is the use of metal particles themselves, which require a high degree of filling of the conductive ink due to their high density. As a result, the flexibility of the eligible conductive coatings and thus the flexibility of the contacted wire is greatly reduced.

A further disadvantage is oxidation processes on the metal particles, as a result of which the conductivity of the conductive ink decreases over a longer period of time.

If solvent-based conductive paints are used, these solvents may under certain circumstances dissolve the conductive foil of the heating element and possibly destroy it. The result here too is an increase in the contact resistance or an uneven contacting of the heating element.

The biggest problem, however, is the even application of the conductive ink. If this is not successful, uneven contact can be expected. The result is different contact resistances, which can lead to lower power consumption and to "hot spots". c) incorporation of the wires during the production process of the film:

By embedding the wires during the production process a reliable all-round contact is guaranteed. Since the wires are completely surrounded by polymer, however, their flexibility is greatly reduced.

Even more problematic, however, is the difficult technical implementation of the process. For subsequent contacting of heating elements, this solution is of course not suitable.

d) Melting of the wires in the electrically conductive foil:

This is only possible when using thermoplastics. However, because of their lack of internal crosslinking, thermoplastics are unsuitable for the production of flexible heating elements, since irreversible changes in shape and thus irreversible changes in the electrical power consumption occur as a result of mechanical or thermal continuous loading.

No. 6,974,935 B2 describes a contacting system for electrically conductive foils.

The power supply is realized there via copper strips, the application of the wires is carried out with the aid of a silver particle-containing conductive ink.

The relative stiffness of the copper strips has the disadvantage that the bendability / flexibility of the resulting heating element is given only transversely to the contacting direction. This excludes applications in which the heating element must have sufficient flexibility in all spatial directions (eg in the case of heating textiles).

The present invention is therefore based on the object of specifying a contacting system and a heating element, in which a simple, uniform, stable, secure and flexible contacting is possible.

According to the invention the above object is achieved with respect to a contacting system with the features of patent claim 1. After that is indicated a: Contacting system, in particular for the electrical contacting of substantially flat heating elements, with a substantially band-shaped or planar shape, wherein the contacting system has a layer-like composite of at least the following components:

a carrier material, a metallic conductor, an electrically conductive layer.

In the inventive manner has been recognized that the proposed contacting system is particularly suitable for contacting flat, flexible heating elements. The production of a layer-like composite of carrier material, metallic conductor and an electrically conductive layer does not significantly impair the flexibility of a (surface) heating element.

Furthermore, it has been recognized that the production of such a composite uniform contact of the metallic lead is achieved without significant transition projections occur. In the proposed solution, the metallic conductor is not surrounded by a conductive paint or the like.

Furthermore, it has been recognized that the contacting system can be used particularly easily, since no gluing or sewing of the metallic conductor on the electrically conductive layer is necessary.

By dispensing with the complete enclosure of the metallic conductor within the contacting system, a higher flexibility and stability is achieved according to the invention.

The contacting system according to the invention can be produced, for example, substantially in strip form and distributed in the form of metered goods. The contacting system makes it possible to contact any heating elements electrically. In this case, a special flexibility is achieved in that the necessary metallic conductor is not rigidly connected to the heating element. The metallic conductor is rather supported by the carrier material of the contacting system and does not reduce the flexibility of the contacting system or the contacted heating element.

Consequently, a contacting system is specified in which a simple, uniform, stable, secure and flexible contacting is possible.

The carrier material of the contacting system may have a film, if appropriate made of a plastic, and / or a leather, textile or needle felt layer and / or a needle or spunbonded nonwoven and / or a filament composite.

The metallic conductor of the contacting system may comprise a wire mesh and / or a wire mesh and / or a wire mesh and / or one or more wires, Lah- nenlitzleiter, Metallflachlitzen, metal crocheted mesh bands or Metallgespinstgimpen.

In an advantageous embodiment, the electrically conductive layer of the contacting system has one or more flexible electrically conductive films based on polymer. By using a flexible film, the flexibility of the contacting system according to the invention can be increased even more.

The electrically conductive layer may comprise metallic and / or non-metallic conductive pigments. If metallic conductive pigments are used, it has to be considered that due to the high density of the metal to achieve a certain degree of filling, a comparatively high metal content must be set. As a result, however, the flexibility of the electrically conductive layer may decrease.

Therefore, a development of the invention is preferred in which the electrically conductive layer has predominantly non-metallic conductive pigments. This embodiment makes it possible to achieve a particularly flexible contacting system.

The electrically conductive layer may have a resistivity of about 0.1 to about 10 Ω · cm. Preference is given to a specific resistance of about 0.1 to about 1 Ω x cm. In a preferred development, the electrically conductive layer is solvent-soluble or swellable by organic solvents. As a result, it is particularly easy to produce a bond with the carrier material and the metallic conductor with the electrically conductive layer. Furthermore, the production of a heating element is simplified. In this case, the loosened or swollen portion of the electrically conductive layer can serve as an adhesive for producing a cohesive composite.

Alternatively, can be dispensed with the swellability by a solvent, if the electrically conductive layer contains at least portions of thermoplastic material. The thermoplastic can be melted by applying high heat (e.g., ironing) and then pressed on the layer to be contacted. This makes it possible to produce a substance of a coherent bond between the contacting system according to the invention and a surface to be contacted without the use of solvents. The achievable contact resistance is particularly low. By forming the electrically conductive layer as a thin layer and / or the only partial use of thermoplastic material in the electrically conductive layer, the disadvantages of thermoplastic materials mentioned above are also avoided.

Advantageously, the contacting system according to the invention may additionally comprise a temperature sensor. The temperature sensor can be connected to a further provided control electronics. As a result, the heating power of the contacted heating element can be controlled precisely with the aid of the contacting system according to the invention. Furthermore, it can be prevented that there is an overheating when contacting a heating element.

In a further development of the last-mentioned embodiment, the temperature sensor has a thermocouple, a resistance thermometer or the like. For example. The temperature sensor can consist of a Ni-Cr-Ni thermocouple. Alternatively, the temperature sensor can have a resistance thermometer, in particular a PTC resistance thermometer. Pt-100 temperature probes are the most widely used in this field. The temperature sensor can be arranged in the immediate vicinity of the metallic conductor in order to detect possibly occurring overheating. In a particularly preferred manner, the temperature sensor is PTC thermistor. mometer formed and has a wire-like shape. This wire can be arranged parallel to the metallic conductor within the contacting system. For this purpose, the wire-shaped temperature sensor preferably extends between the electrically conductive layer and the carrier material in the immediate vicinity of the metallic conductor. However, such a wire-shaped temperature sensor can also be arranged below the electrically conductive layer or on the carrier material. Furthermore, it is possible that a wire-shaped temperature sensor in the form of a sewing thread is routed at regular intervals from the top of the contacting system on the underside and back. This results in a side effect of a mechanical stabilization of the contacting system by the temperature sensor.

The above-indicated object is achieved with regard to a heating element having the features of patent claim 11. This claim specifies:

Heating element having a substantially sheet-like shape, wherein the heating element has a layer-like composite of a contacting system and a heating layer.

The heating element according to the invention is characterized by a particularly simple, uniform, stable, secure and flexible contacting of the heating layer by means of the contacting system according to the invention.

In order to avoid repetition, reference is made to the statements relating to the contacting system according to the invention with regard to further inventive advantages of the specified heating element.

The heating layer of the heating element may comprise one or more electrically conductive films or layers based on polymer and / or one or more layers of conductive textiles, carbon fibers or mixtures of carbon fibers and carrier fabrics.

In a preferred embodiment, the heating layer of the heating element is designed to be flexible. This results in desirable flexibility of the entire heating element in conjunction with a flexible contacting system. It is preferred that the heating element has flexibility in all surface directions.

In a further embodiment, the heating element has a temperature sensor. In this case, it is particularly preferred that the temperature sensor is arranged next to the contacting system and possibly runs parallel to this on the heating element. This embodiment of the heating element is particularly preferred if the contacting system itself has no temperature sensor. With regard to possible designs and positioning of a temperature sensor, reference is made to the above statements with respect to the contacting system to avoid repetition.

The object indicated above is furthermore achieved with regard to a method for producing a contacting system having the features of patent claim 15. This specifies:

A method of making a contacting system, the method comprising the steps of:

Providing a carrier material,

Providing a metallic conductor,

Providing an electrically conductive layer,

Producing a bond between the carrier material and the metallic conductor,

Assembly of the composite and the electrically conductive

Layer.

In accordance with the invention, a bond between the carrier material and the metallic conductor is first produced for producing the contacting system according to the invention.

Only then is the composite of the carrier material and the metallic conductor merged with the electrically conductive layer. By this procedure, a particularly high stability of the contacting system and a achieved particularly secure contact of the metallic conductor through the electrically conductive layer.

The production of a bond between the carrier material and the metallic conductor can be accomplished by sewing the metallic conductor onto the carrier material.

Furthermore, the joining of the composite of the carrier material and the metallic conductor to the electrically conductive layer can be achieved by dissolving or swelling the electrically conductive layer by means of an organic solvent. Thereafter, the dissolved electrically conductive layer can be pressed onto the composite between the metallic conductor and the carrier material and glued. This results in a secure cohesive connection.

A particularly preferred embodiment of the method according to the invention for producing a contacting system has the following steps:

a) sewing the metallic conductor onto the carrier material, b) moistening this composite with an organic solvent, c) laminating the electrically conductive layer onto this composite, d) drying / evaporating the solvent.

After complete evaporation of the solvent, a cohesive bond is formed according to the invention. At the same time, a high degree of flexibility of the overall system is maintained.

Finally, the stated object is achieved with regard to a method for producing a heating element having the features of patent claim 18. It is proposed:

A method of making a heating element, the method comprising the steps of: Providing a contacting system,

Providing a heating layer,

Establishing a bond between the Kontaktierungssystem- and the heating layer.

The bond between the contacting system and the heating layer can be produced by dissolving or swelling the electrically conductive layer of the contacting system by means of an organic solvent. Thereafter, a cohesive connection can be established between the contacting system and the heating layer. Furthermore, a secure and flexible contacting of the heating layer is ensured.

In a development of the method according to the invention, in addition to the cohesive connection, a form-fitting connection between the contacting system and the heating layer can be established. For example. The two (flat) elements can be sewn together. As a result, a particularly stable heating layer is realized.

A particularly preferred embodiment of the method according to the invention for producing a heating element has the following steps:

a) moistening the underside of the contacting system with a suitable organic solvent, whereby the electrically conductive layer of the contacting system is swollen or slightly dissolved,

b) assembling the pretreated contacting system and the heating layer and then pressing them together,

c) drying and subsequent evaporation of the solvent, for example. By a short bake phase at a temperature of about 60 ⁰ C to about 90 ⁰ C, the contacting system dries completely on the heating layer.

The use of volatile organic solvents ensures that a good contact of the contacting system with the heating layer is reached after only a short time. An alternative embodiment of the two proposed methods can be realized if the electrically conductive layer of the contacting system and / or the heating layer of the heating element contain at least a portion of one or more thermoplastics. Accordingly, to produce the contacting system according to the invention, the electrically conductive layer can be melted and connected by pressurization with the metallic conductor and the carrier material. Furthermore, a bond between the contacting system and the heating layer of the heating element can be produced by the aforementioned method step. In this case, the electrically conductive layer of the contacting system and / or the heating layer of the heating element is melted and joined the two sheet-like elements under pressure to a cohesive composite. This can be realized, for example, by ironing.

If desired, the mechanical strength of the heating element can be additionally increased by sewing the contacting system with the heating layer.

To avoid repetition, reference should be made to the statements relating to the respective device with regard to advantageous embodiments of the proposed method.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, on the one hand to the subordinate claims, on the other hand to refer to the following explanation of a preferred embodiment of the contacting system according to the invention and the heating element according to the invention with reference to the drawings. In conjunction with the explanation of the preferred embodiments with reference to the drawings, generally preferred embodiments and developments of the teaching are explained. In the drawing shows

1 is a perspective view of an embodiment of the contacting system according to the invention,

2 shows a cross section through the contacting system of FIG. 1, Fig. 3 is a diagonal top perspective view of a

Embodiment of the heating element according to the invention, and

4 shows a cross section through the heating element from FIG. 3.

Fig. 1 shows a perspective view of an embodiment of the contacting system according to the invention. An electrically conductive layer 1 is arranged on the underside of the contacting system. On the upper side of the contacting system is a carrier material 2. Between these two layers, a metallic conductor 3 is arranged.

In the embodiment shown, the electrically conductive layer 1 has a flexible, electrically conductive, polymer-based film. The carrier material 2 may consist of a textile or leather layer, a spunbonded fabric or the like. The metallic conductor 3 is a wire or a stranded wire in the exemplary embodiment shown. However, the metallic conductor 3 may also consist of a wire mesh, a wire mesh, a metal spun or the like.

Fig. 2 shows a cross section through the contacting system shown in Fig. 1. This illustration further clarifies the basic structure of the contacting system according to the invention.

FIG. 3 shows a perspective view, viewed obliquely from above, of an embodiment of the heating element according to the invention. On the underside of the heating element is a heating layer 4. On the heating layer 4, two contacting systems according to the invention have been applied. The contacting system consists - from bottom to top - of an electrically conductive layer 1, a metallic conductor 3 and a substrate 2. In the manufacture of the heating element is particularly important to establish a good electrical contact between the contacting system and the heating layer 4. For this purpose, a flexible, electrically conductive film based on polymer has been used for the contacting system as an electrically conductive layer 1. The electrically conductive film can be dissolved or swollen by organic solvents. In this condition, the contacting system can then be applied to the heating Layer 4 apply. By pressing and drying the entire composite, a secure connection between the contacting system and the heating layer 4 is produced. At the same time, a particularly flexible and secure contacting of the heating layer 4 by the electrically conductive layer 1 is realized.

FIG. 4 shows a cross section through the heating element from FIG. 3. This clarifies the basic construction of the heating element according to the invention once more.

Finally, it should be emphasized that the exemplary embodiments described above discuss the claimed teaching, but do not restrict it to one of these exemplary embodiments.

Claims

P atentan pr oce 1. contacting system, in particular for the electrical contacting of substantially flat heating elements, with a substantially band-shaped or planar shape, wherein the contacting system has a layer-like composite of at least the following components: a carrier material (2), a metallic conductor (3), an electrically conductive layer (1). 2. contacting system according to claim 1, characterized in that the carrier material (2) has an optionally made of a plastic film and / or a leather, textile or Nadelfilzschicht and / or a needle or spunbonded fabric and / or a filament composite. 3. contacting system according to claim 1 or 2, characterized in that the metallic conductor (3) comprises a wire mesh and / or a knitted wire and / or a Drahtgewirk and / or one or more wires, Lahnenlitzleiter, Metallflachlitzen, metal crochet grille bands or metal weave gimp. 4. contacting system according to one of claims 1 to 3, characterized in that the electrically conductive layer (1) comprises one or more flexible, electrically conductive films based on polymer. 5. contacting system according to one of claims 1 to 4, characterized in that the electrically conductive layer (1) has metallic and / or non-metallic conductive pigments. 6. contacting system according to claim 5, characterized in that the electrically conductive layer (1) comprises predominantly non-metallic conductive pigments. 7. contacting system according to one of claims 1 to 6, characterized in that the electrically conductive layer (1) has a specific resistance from about 0.1 to about 10 Ω ^» cm, more preferably from about 0.1 to about 1 Ω ^» cm. 8. contacting system according to one of claims 1 to 7, characterized in that the electrically conductive layer (1) is dissolvable or swellable by organic solvents. 9. contacting system according to one of claims 1 to 8, characterized by a temperature sensor. 10. contacting system according to claim 9, characterized in that the temperature sensor comprises a thermocouple, a resistance thermometer or the like, wherein the temperature sensor is arranged next to the metallic conductor (3) and / or extends substantially parallel thereto. 11. Heating element having a substantially sheet-like shape, wherein the heating element has a layer-like composite of a contacting system according to one of claims 1 to 10 and a heating layer (4). 12. Heating element according to claim 11, characterized in that the heating layer (4) has one or more electrically conductive films or layers based on polymer and / or one or more layers of conductive textiles, carbon fibers or mixtures of carbon fibers and carrier fabrics. 13. Heating element according to claim 11 or 12, characterized in that the heating layer (4) is designed to be flexible. 14. Heating element according to one of claims 11 to 13, characterized by a flexibility in all surface directions. 15. A method for producing a contacting system according to any one of claims 1 to 10, wherein the method comprises the following steps: Providing a carrier material (2), providing a metallic conductor (3), Providing an electrically conductive layer (1), Producing a bond between the carrier material (2) and the metallic conductor (3), Assembly of the composite and the electrically conductive Layer (1). 16. The method according to claim 15, characterized in that the production of a composite between the carrier material (2) and the metallic conductor (3) has the sewing of the metallic conductor (3) on the carrier material (2). 17. The method according to claim 15 or 16, characterized in that the joining of the composite and the electrically conductive layer (1) comprises the dissolution or swelling of the electrically conductive layer (1) by means of an organic solvent and the subsequent production of a material connection , 18. A method for producing a heating element according to any one of claims 11 to 14, wherein the method comprises the following steps: Provision of a contacting system according to one of claims 1 to 10, Providing a heating layer (4), Establishing a bond between the Kontaktierungssys- tem and the heating layer (4). 19. The method according to claim 18, characterized in that the production of a bond between the contacting system and the heating layer (4) the dissolution or swelling of the electrically conductive layer (1) of the contacting system by means of an organic solvent and the subsequent production of a material connection having. 20. The method according to claim 18 or 19, characterized in that the production of a bond between the contacting system and the heating layer (4) additionally a positive connection, in particular by sewing has.