EP3337291B1 - Heating device, cooking appliance with a heating unit, and method for making a heating element - Google Patents

Description

The invention relates to a cooking appliance with a heating device with a flat heating element and a holding device for this heating element.

From the DE 19638640 A1 Such a heating device and a hob provided with it are known, a heating element for this purpose being separated from metal foil with a geometric pattern. In this way, a certain heating conductor length can be achieved by individual heating conductors. Furthermore, a large radiating surface of the heating element can be achieved upwards towards a hob plate and an erected cooking vessel.

The JP S40 26128 Y1 shows a heating device with a grid in which parallel heating wires are incorporated. The heating wires run between two opposing holding clamping rails into which they are clamped together with the grid. This is also used to make electrical contact. The heating device is used in a toaster.

From the FR 746604 A as well as the BE 392717 A heaters are known as hot plates for contact cooking. An oval-ring-shaped heating element is placed on the underside of a mounting surface and is held by a holder. This heating element is designed as a type of grid or fabric.

From the CH 272523 A a hot plate is known as a heater. A heating element in the form of a resistance wire, which has been processed into a fabric together with non-metallic threads, is pressed into a plastic and electrically insulating material to form a plate. Thus, this fabric or the heating element itself is held by complete embedding.

Task and solution

The invention is based on the object of creating a cooking appliance mentioned at the beginning with which problems of the prior art can be solved and in particular it is possible to reliably and inexpensively manufacture and install heating elements for advantageously usable heating devices in cooking appliances.

This object is achieved by a cooking appliance with the features of claim 1. Advantageous and preferred embodiments of the invention are the subject matter of the further claims and are explained in more detail below.

It is provided that the heating device has a flat heating element and a holding device for the heating element. The heating element is held on the holding device along an outer edge or its outer edge. At least 70% of its area runs freely between the holding device or within the holding device, advantageously at least 85%. This means that holding devices or other holding means do not attack or support this area portion either on an upper side or on a lower side of the heating element. This enables the heating power of the heating element to be radiated very well over a large area.

According to the invention, the heating element is a grid or a fabric that consists at least partially of heating conductor material or has heating conductor material. Such a grid or fabric can advantageously consist of thin heating element sections, for example of wires or threads, with intermediate surfaces or free surfaces in between. The heating element sections in turn can either themselves consist of heating conductor material or be at least partially coated with such material, for example only on one side pointing in one direction. Alternatively, they can also be coated or sheathed all around or completely with heat conductor material. As a result of the design as a grid or fabric, such a heating element can have a plurality of intermediate surfaces between the heating element sections mentioned or between the wires or threads.

In the case of a grid, the intermediate surfaces can advantageously have a larger surface area of the entire heating element than its heating element sections or wires. Such a grid can also be punched or etched out of a flat material, so that a grid shape remains, so to speak. The total area of the intermediate surfaces can be larger than the total area of the wires or threads. It is advantageously 35% to 90% of the total area of the heating element, particularly advantageously 60% to 80%.

In the case of a heating element in the form of a fabric, which can be woven either from wires or from threads or from a mixture thereof, the intermediate areas can be relatively small. Then the total area of the intermediate surfaces or the free areas is smaller than the total area of the wires or threads. It is advantageously 5% to 40% of the total area of the heating element, particularly advantageously 10% to 30%.

In an advantageous embodiment of the invention, the heating element is held at least at several holding points of the holding device. Such breakpoints can be advantageous along a Stop lines run, in particular the stop points are provided continuously as a stop line or several stop lines.

In an embodiment of the invention, it is possible that a flat reflector is provided for the heating element in a direction away from a heating direction of the heating element, for example in the direction of a hob plate of a hob, advantageously on a bottom side of the heating device. Such a reflector can particularly advantageously be held on the holding device under the heating element. It can be made of metal, for example as a polished metal surface or the like, in order to reflect the downwardly radiated heating energy as well as possible upwards in the heating direction or in the direction of an aforementioned hob plate. The reflector can be flat, curved or structured.

In an advantageous embodiment of the invention, the holding device is designed to be circumferential or closed. This can be a type of ring, advantageously with the aforementioned holding line or the set of holding points for the heating element thereon, which correspond to its outer contour. The shape of the heating device can in principle be of any desired shape, for example also round. However, it is advantageous that it is rectangular or at least in the form of a parallelogram. As a result, a largely constant current flow and thus a largely, advantageously completely, uniform power density can be achieved within the flat heating element. For example, a current can flow from one side of the parallelogram to the opposite side.

The holding device advantageously limits a lateral or lateral expansion of the heating device. The heating element is arranged within it and extends there in terms of area, advantageously closed. This means that the heating element runs only within the holding device. Thus, the holding device can advantageously also form thermal insulation at the same time, as is the case with radiant heating devices and those mentioned at the outset DE 19638640 A1 is known.

An electrical contact to the heating element can also run along the holding device or at least along the holding device or be integrated therein. For this purpose, the heating element can have two connection contacts on opposite outer sides or outer edges. Of course, this is again particularly easy and can be carried out easily with a heating element in a rectangular shape. The connection contacts can be designed as contact strips, for example as thin metal strips. The contact strips can be attached to outer edges and thereby also provide electrical contact the heat conductor material. They can be folded around the outer edges for fastening and thus enclose the outer edges between them or be welded with edge strips along the outer sides, advantageously both.

In a further embodiment of the invention, it is possible that a central holder is provided in a central area of the heating device or the heating element, in particular at a center point, for holding in this central area. In this way, excessive sagging of a heating element that is not inherently stable can be prevented in the central area. As an alternative to a holder at essentially one point, a linear holder can also be provided on such a central holder. In the case of a rectangular or parallelogram-shaped heating element, in particular, this runs along a center line so that the flat heating element is held or supported uniformly. Such a central holder can be connected to the rest of the holding device, for example to its lower end. A kind of common base can thus be provided.

In a further embodiment of the heating device, mechanical stabilization of the heating element can be achieved in that the heating element is structured or deformed three-dimensionally perpendicular or perpendicular and parallel to the opposite outer edges or contact strips. The heating element can, for example, have a corrugated, sinusoidal or sawtooth-shaped structure. Alternatively, it can have trench-shaped or crater-shaped stabilizing impressions that are not directed or have no orientation as mentioned above. Corresponding measures to stabilize free areas are of sheets or the like. known.

In an advantageous embodiment of the invention, the holding device, particularly advantageously also a central holder as described above, is arranged on a thermal insulation base. In principle, a structure similar to that mentioned above can be used DE 19638640 A1 or another conventional radiant heater in which a strip-shaped elongated heating element is partially inserted directly into such a thermal insulation underlay.

If the heating element has the aforementioned form of a grid or a fabric, it can advantageously consist of elongated heating element sections which cross or are brought together in different directions. Such a fabric consists in the usual way of warp threads and weft threads. In this case, only one of the two types of threads is advantageously electrically conductive for the heating element function or has heating conductor material or consists of heating conductor material. The other thread then consists of an electrical one insulating material and can above all have a mechanical supportive effect. Ceramic fibers, basalt fibers or carbon fibers are suitable for this. The advantage if only one of the two threads is electrically conductive or has the heating element function is that there is then no electrical contact and, above all, no current flow at the points of intersection with the other threads. This cannot be precisely determined in advance with such an abutting contact and would in some cases also be problematic in the case of surface oxidation. In addition, it is much easier to set a specific distribution of the current density and thus also the power density.

As an alternative to the aforementioned threads, which advantageously each consist of a large number of fibers in straight or twisted or twisted form, so-called monofilaments or wires can also be used. Such wires could also consist of a suitable metal, at least for the heating element function, and be electrically conductive and also fulfill the heating element function. Metal alloys made of, for example, nickel and chromium or iron, chromium and aluminum are suitable here.

In a further possible embodiment of the invention, wires in one direction could also be combined with threads in the other direction. In this case, the wires can again advantageously consist of heating conductor material or have such a material for the heating element function.

In yet another embodiment of the invention, a heating element can have the shape of a grid and have grid sections that run essentially at right angles. Such a grid can consist, as it were, of intersecting heating element sections, which are, however, made in one piece, for example by punching out of a corresponding film or a thin heating conductor material. Such a heating element can then be produced in one piece and in one piece.

The heating element can advantageously have heating element sections and perforations running between them as intermediate surfaces. The proportion of the area of the openings or intermediate surfaces is advantageously greater than the proportion of the area of the heating element sections, particularly advantageously by a factor of 2 to 20, in particular by a factor of 5 to 10. If a heating element consists of the aforementioned fabric, a significantly lower factor is advantageous the area proportion of the intermediate surfaces can be smaller than the area proportion of the heating element sections.

In a further embodiment of the invention, the heating element, advantageously on electrically conductive heating element sections, can be at least partially coated with a catalytically active material. The entire heating element or some heating element sections or some of the individual threads or wires can indeed also consist entirely of such a catalytically active material. However, this is of no use in terms of effectiveness, since a catalyst acts on its surface, and it would probably be very cost-intensive in view of the often very expensive materials. It is possible that not all parallel and adjacent heating element sections or threads or wires are coated with or have such a catalytically active material, but only, for example, every second, every third or every fourth.

Such a catalytic effect directly on the heating element can be advantageous applications of a heating device according to the invention especially where the heating element heats air directly and not only serves as a radiant heater. In this way, air flowing past can be cleaned.

A cooking device according to the invention is a hob with a hob plate. At least one previously described heating device, advantageously several, is arranged under the hob plate. In this case, such a heating device can in principle be used and also operated like a radiant heating device known per se. The hob plate should be as permeable as possible to thermal radiation, for example also consist of glass ceramic, as is generally customary. In the invention, the holding device presses the heating element as flat as possible onto the underside of the hob plate, which is electrically insulating and can also consist of glass ceramic, for example. Then the heating device or the heating element works as a contact heater and is operated with low voltage, i.e. 50 V AC or 120 V DC. The heating element is operated in a temperature range of a few 100 ° C., advantageously 200 ° C. to 500 ° C., but below the more than 1,000 ° C. at which radiant heaters usually work.

A method for producing a heating element, as it can be used in particular in the aforementioned cooking appliance according to the invention, provides that a grid or fabric is produced, as has been described above. It has heating element sections and a heating element function and is flat. It can be woven as a fabric with appropriate warp threads and weft threads or warp wires and weft wires. Such a material can either already be produced in strip form with a width that is subsequently also desired for the heating element or the heating device. Alternatively can it can be made as a larger area and a strip cut out of it. As an alternative to such a production, a corresponding grid of a heating element can be punched out, etched out or lasered out of heating conductor material.

In a subsequent step, a contact strip made of electrically conductive strip material is attached to a strip of the desired width of the heating element in a continuous process on its two opposite outer edges. For this purpose, the outer edges of the strip of the heating element can be folded into these contact strips. Correspondingly electrically conductive strip material can be, for example, a thin sheet of electrically conductive material.

In a further step, the contact strips are mechanically and electrically connected to the strip from the grid or the fabric as a composite. This is advantageously done by welding. This connection is particularly advantageously carried out in a continuous process, wherein both the said strip of the heating element and the strip material for the contact strips can be present in great lengths and, for example, on drums or the like. can be wound, from which it is then unwound. Such contact strips not only serve for uniform and reliable electrical contact, but can also provide a certain mechanical strength. This does not necessarily replace the holding device mentioned at the beginning, even if this would be possible. This also facilitates handling of the heating element when assembling a heating device.

A heating element is then cut to length from the elongated strips as a composite. This heating element is then built into a heating device in the manner described above.

In a further embodiment of the invention, it can be provided that solid or stranded electrical connection lines are attached to one contact strip in each case. This is advantageously done by welding. Plug contacts can possibly also be attached directly or welded on, in particular plug contact lugs. In this way, electrical connection cables can be easily attached.

The subdivision of the application into individual sections and subheadings does not limit the general validity of the statements made under these.

Brief description of the drawings

Fig. 1

eine starke Vergrößerung eines Gewebes mit Kett-Fäden aus Heizleitermaterial und mit Schuss-Fäden aus elektrisch isolierenden Fasern,

Fig. 2

eine mögliche Ausgestaltung eines Kochfelds mit einer Heizeinrichtung mit einem Heizelement gemäß der Erfindung,

Fig. 3

eine schematische Vorrichtung zur Herstellung eines Heizelements aus einem Gewebe entsprechend Fig. 1,

Fig. 4

eine Ausgestaltung eines Heizelements aus einem Gewebe entsprechend Fig. 1 mit einer wellenartigen Struktur,

Fig. 5 und 6

verschiedene Draufsichten auf gitterartige Heizelemente mit breiten Kontaktstreifen an den Seiten,

Fig. 7

eine schematisch dargestellte Möglichkeit einer gespannten Anordnung eines Heizelements in einer Heizeinrichtung,

Fig. 8

eine vereinfachte Darstellung eines Backofens mit Heizeinrichtungen, der nicht zu der Erfindung gehört, als Unterhitzeheizkörper und Oberhitzeheizkörper und

Fig. 9

eine schematische Darstellung eines weiteren Backofens mit einer Heizeinrichtung, der nicht zu der Erfindung gehört, samt Katalysatorfunktion an einem Gebläse für eine Heißluftfunktion.

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings show:

Fig. 1

a strong enlargement of a fabric with warp threads made of heat conductor material and with weft threads made of electrically insulating fibers,

Fig. 2

a possible embodiment of a hob with a heating device with a heating element according to the invention,

Fig. 3

a schematic device for producing a heating element from a fabric accordingly Fig. 1 ,

Fig. 4

an embodiment of a heating element made of a fabric accordingly Fig. 1 with a wave-like structure,

Figures 5 and 6

various top views of grid-like heating elements with wide contact strips on the sides,

Fig. 7

a schematically shown possibility of a tensioned arrangement of a heating element in a heating device,

Fig. 8

a simplified representation of an oven with heating devices, which does not belong to the invention, as a bottom heating element and top heating element and

Fig. 9

a schematic representation of another oven with a heating device, which does not belong to the invention, including a catalyst function on a fan for a hot air function.

Detailed description of the exemplary embodiments

In the Fig. 1 a fabric 10, which consists of warp threads and weft threads 14, is shown in high magnification. Both threads are not designed to run completely straight here, which results in good structural cohesion of the fabric 10. The warp threads 13 consist of heating conductor material, for example of alloys with nickel and chromium or with iron, chromium and aluminum mentioned at the beginning. The warp threads 13 are advantageously designed as fine wires.

The weft threads 14 can in principle also have a heating element function, but they are advantageously electrically insulating and, above all, provided for the support or mechanical strength of the fabric 10. They consist of electrically insulating and correspondingly mechanically strong and above all temperature-resistant material; ceramic fibers, basalt fibers, carbon fibers or aramid fibers are advantageous depending on the maximum temperature and the area of application of a heating element. Multifilaments are particularly advantageous here.

A thickness or a diameter of the warp threads and / or the weft threads can be dimensioned according to the application, for example between 0.05 mm and 1 mm, advantageously between 0.1 mm and 0.5 mm.

The Fig. 2 shows an example of a possible configuration of a heating device 20 with a finished heating element 11 in which a fabric 10 is processed, as will be explained below. The flat heating element 11 is arranged on an externally extending, preferably rectangular retaining edge, advantageously clamped or inserted into slots and held therein. The retaining edge 21, as well as a central bracket 23 in the middle for the heating element 11, consist of a suitably temperature-resistant and highly insulating material, for example pressed vermiculite or similar material, as is commonly used for radiant heating devices in hobs. The retaining edge 21 and the central holder 23 stand on an insulating pad 24, which consists of the same material. Under certain circumstances, the parts can even be manufactured at least partially in one piece. A reflector 26, which can also be held by the central holder 23 and the holding edge 21, runs below the heating element 11. It can run flat or be slightly curved in each case by means of a sag in order to possibly achieve a better reflection effect.

The heating device 20 is installed as a heater in a hob 30 according to the invention, as in FIG Fig. 2 is shown. The hob 30 has a hob plate 32, under or on the underside of which the heating device 20 is arranged in a pressed manner. As with otherwise known glass ceramic hobs with radiant heating underneath, the heat generated by the heating device 20 or the heating element 11 is radiated upwards through the hob plate 32 into a pot placed thereon. However, this essentially corresponds to an analogous replacement of a radiant heating device mentioned above, for example, and therefore does not need to be explained in more detail.

In the Fig. 3 is shown as in a device 34 made of a tissue 10 accordingly Fig. 1 a finished heating element 11 is produced. The tissue 10 is cut or is present in elongated strips and is inserted into the device 34. The electrically insulating weft threads run in the direction of passage and the warp threads with the heating element function in a direction transverse to it. Partially folded contact strips 15a and 15b are then possibly brought up to the outer sides and folded onto one another by folding means (not shown), the side edges of the fabric 10 being folded into the folded contact strips 15a and 15b. The overlap here can be between 2 mm and 20 mm, advantageously 5 mm to 15 mm.

After the folding, a roll seam welding device 17a is provided on the left and a roll seam welding device 17b is provided on the right. These weld the fabric 10 or the warp threads 13 made of metal to the contact strips 15a and 15b, and under certain circumstances they can also take over the folding. The welding creates a secure and stabilizing mechanical connection on the one hand, and an electrical connection on the other.

The finished desired heating elements 11 are then cut to the appropriate length by means of a cutting device 18. The warp threads with the heating element function run from one contact strip 15a to the other contact strip 15b.

Here it is also shown schematically how electrical connections 27 can be attached to the contact strips 15a and 15b, for example as short connecting wires. For this they can be welded on. Alternatively, fixed contact plugs could be attached or welded as contact shoes or flat tabs.

It is easy to imagine that the heating element 11 according to FIG Fig. 3 has a rectangular shape, for example a square shape. In principle, a form of a parallelogram would also be possible, but practical applications for this are rather rare.

The Fig. 4 shows an example of a further possible embodiment of a heating element 11 'similar to that which is shown at the end of the method according to FIG. Fig. 3 is obtained. Here, a corrugated or trench-like structure is introduced into the heating element 11 'or into the fabric 10' made of warp threads 13 'and weft threads 14' and, above all, in the lateral contact strips 15a 'and 15b'. This serves to stabilize the heating element 11 'as a whole, and in particular the tissue 10'. Instead of the trenches running transversely to the contact strips 15a 'and 15b' Inclined or longitudinal trenches or similar structures could also be introduced, for example also crossed structures in the manner of a known diamond pattern. Likewise, there could be more and more closely arranged trenches, so that the aforementioned corrugated structure is created. The trenches 10 'could also be modified in such a way that they are shaped to a point or curved, as it were, as a type of the aforementioned sawtooth. In yet another modification, the structures could be introduced in both directions, for example alternately.

In yet another modification, individual smaller areas could be impressed in a distributed manner, for example as craters or elevations.

In the Fig. 5 an embodiment of a further heating element 111 is shown in plan view, which is designed as a grid or is grid-like. A centrally arranged lattice structure 110 replaces, so to speak, the fabric 10 of Fig. 1 and 3 . Just like the fabric 10, as has been described above, a strip of a corresponding width is folded in between two contact strips 115a and 115b, welded and thus mechanically and electrically connected to it. The grid 110 has been produced here by etching from a thin film of a heat conductor material. Alternatively, it could be punched or lasered. Here, too, the current flow is from one contact strip 115a to the other contact strip 115b. For this purpose, the pattern of the structure in the direction of the longitudinal direction of the contact strips 115 is advantageously regular, which can be particularly advantageous in general for a heating element according to the invention.

In the Fig. 6 a further embodiment of a heating element 211 is shown. This is also designed like a grid, but with a different grid than according to FIG Fig. 5 . Elongated heating element sections are designed in the manner of waves that are connected to one another by webs. Such a grating 210 is advantageously produced as before for the grating 110 of FIG Fig. 5 described. Furthermore, this grid 210 is also folded into two contact strips 215a and 215b in the manner described for the mechanical and electrical connection.

In the Fig. 7 is a modification of the representation of the Fig. 2 shown with a heater 320 that is permanently tensioned in a special way. In the left area of a retaining edge 321, an electrical connection 327 runs down from the left edge of the heating element 311, which also provides a fastening, possibly in addition to a holder on the retaining edge 321. In the right area, an electrical connection 327 also extends down. A tension weight 329, which is the right connection, is symbolically arranged on this, so to speak 327 pulls down, so to speak. A spring 328 arranged to the left of the connection 327 also generates a certain mechanical tension as a pull, which pulls the heating element 311 as smoothly as possible. A shape of the heating element 311 that is as flat and planar as possible can thus be achieved.

In the Fig. 8 an oven 36 with an oven muffle 37 and an oven door 38, which does not belong to the invention, is shown as a further exemplary cooking appliance in addition to a hob. A heating element 11 is provided, for example, in one piece as a bottom heating element below the oven muffle 37, specifically below a glass ceramic plate 39, which in turn is particularly permeable to thermal radiation as in the case of the hob 30 of the Fig. 2 . The exact holding device for the heating element 11 is not shown here, but can, for example, according to FIG Fig. 1 or 7th be. It can also be seen that this lower heating element 11 can be relatively large.

The upper heating element is provided in the upper area of the oven muffle 37 or below a muffle ceiling, for example through the combination of two narrow heating elements 11.

Both the heating element for the upper heat and that for the lower heat can be made in one piece or consist of an arrangement of rectangular heating elements that have the same or different side and length dimensions. It is thus possible to set both the top heat and the bottom heat partially differently for even heating or browning of the food to be cooked, roasted or grilled.

In the Fig. 9 is off for the oven 36 Fig. 8 A hot air function is shown separately just for the sake of clarity. A fan 41 provided for this purpose is arranged in the rear area of the oven muffle 37. A heating element 11 is arranged in the air path, advantageously for thermal reasons behind the fan, which heats the air blown or conveyed through it for the hot air function of the oven 36. In addition, the heating element 11 can be at least partially coated here with a catalytically active material, advantageously be completely coated. In this way, a new type of directly heated catalyst heating element can be created for an oven, as a result of which, for example, the circulating air in such an oven 36 can be cleaned in order to reduce contamination and unpleasant odors.

Here, too, a holding device for the heating element 11 is not shown in detail, but it is easy to imagine. In this way, the two contact strips 15 on the sides are again particularly suitable for attaching the heating element 11.

Claims (10)

1. Cooking appliance in the form of a hob (30, 330), having an electrically insulating hob plate (32, 331), wherein at least one heating device (20, 320) is arranged beneath said hob plate, wherein the heating device includes a planar heating element (11, 311) and a holding device (21, 23, 321) for said heating element,
   characterized in that
   the heating element is held along an outer edge on said holding device and, by way of at least 70% of a surface area of said heating element, runs freely within said holding device, wherein said holding device (21, 23, 321) presses the heating element (11, 311) flat against the bottom side of the hob plate (32, 331), wherein said heating element has a lattice or a weave (10) which at least partially contains a heating conductor material, and wherein during operation a 50 V AC voltage or a 120 V DC voltage is applied as a low voltage to the heating device (20, 320).
2. Cooking appliance according to claim 1, characterized in that the heating element (11, 311) is held at least at holding points of said holding device (21, 23, 321), preferably on holding points along a holding line.
3. Cooking appliance according to claim 1 or 2, characterized in that the heating element (11, 311) is three-dimensionally structured or deformed for mechanical stabilization, preferably in a perpendicular direction or in a direction perpendicular and parallel to opposite outer edges, wherein in particular said heating element has a corrugated, sinusoidal or sawtooth-like structure, or has trench-like or crater-like stabilizing embossed portions (16'), wherein preferably the embossed portions are not directed or do not have an orientation.
4. Cooking appliance according to any of the preceding claims, characterized in that a sheet-like reflector (26) is provided in a direction away from a heating direction of said heating element (11, 311), which reflector is preferably held on said holding device (21, 23, 321) beneath said heating element, wherein in particular the reflector is metallic.
5. Cooking appliance according to any of the preceding claims, characterized in that the holding device (21, 321) is formed in an annularly circumferential manner, in particular is closed, preferably rectangular, and substantially bounds a lateral extent of said heating device (20, 320), wherein said heating element (11, 311) is arranged and runs within said lateral extent of said heating device.
6. Cooking appliance according to any of the preceding claims, characterized in that a heating element (11, 311), as viewed from a heating direction, has a rectangular shape with two connection contact-making arrangements (15a, 15b) on opposite outer sides.
7. Cooking appliance according to any of the preceding claims, characterized in that two opposite outer edges of said heating element (11, 311) comprising said lattice or said weave (10) are connected to contact strips (15a, 15b) composed of electrically conductive strip material, preferably are folded therein, wherein preferably said contact strips (15a, 15b) are mechanically and electrically connected to said heating element (11, 311) as a composite in a continuous process, in particular are welded.
8. Cooking appliance according to any of the preceding claims, characterized in that said lattice or said weave (10) of said heating element (11, 311) has warp wires or warp threads (13) and weft wires or weft threads (14), wherein preferably exclusively said warp wires or said warp threads (13) are electrically conductive for the heating element function, wherein in particular said heating element is in the form of a lattice with wires or threads (13, 14) running substantially at right angles.
9. Cooking appliance according to any of the preceding claims, characterized in that said heating element (11, 311) consists of heating element sections and of intermediate areas which run between said heating element sections, wherein in particular the surface area proportion of said intermediate areas is greater than a surface area proportion of said heating element sections, preferably by a factor of 2 to 20, in particular by a factor of 5 to 10.
10. Cooking appliance according to any of the preceding claims, characterized in that said heating element (11, 311), preferably on electrically conductive heating element sections, is at least partially coated with a catalytically active material, or in that wires or heating element sections are provided which are directly composed of catalyst material.

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