EP2056649B1 - Holder for an electric heater and electric heating device and method for production - Google Patents

Description

Field of application and state of the art

The invention relates to a support for an electric heater, which consists of insulating material and on the upper side at least one heating element is arranged. The heating element is elongated and runs in upwardly open paths on the top of the carrier. Furthermore, the invention relates to an electric heater with such a carrier and a method for producing such a carrier and such a heater.

It is for example from the EP 612 197 A1 known to form an electric heater in the form of a radiant heater with a similar carrier in which heating elements in the form of Bandheizleitern run in grooves in a prefabricated path on top of the carrier. At certain intervals on the tracks are the side walls the tracks and laterally pressed against the Bandheizleiter to mechanically secure them.

The EP-A-0 035 254 discloses a support for an electric heater together with such a heater with heating elements on an upper side. The elongate heating elements are in recessed tracks that are open at the top for radiating upward to heat a cooking vessel from above on a cooktop panel running above it. Holes are provided in the tracks to force a convection airflow to heat the underside of the hob plate accordingly to increase efficiency.

The DE 520 136 C shows an electric heater with a carrier, which consists of two superimposed parts. At an interface between the parts run semi-circular grooves, which complement each other to form a circumferential, annular channel. In this channel, an elongated heating coil is arranged. The grooves are upwardly and downwardly open with slots, so that from an attached cooking vessel leaking liquid can escape down.

Task and solution

The invention has for its object to provide a support mentioned above, an electric heater with such a carrier and a method for manufacturing, which can be avoided with the problems and disadvantages of the prior art and in particular in the simplest possible way such a heater can be constructed and mounted.

This object is achieved by a carrier with the features of claim 1, an electric heater with the features of claim 8 and method having the features of claims 13 or 14. Advantageous and preferred embodiments of the invention are the subject of the other claims and are explained in more detail below. Some of the features are described only for one embodiment of the carrier, the heater or the respective manufacturing process, but should also be applicable to the other versions independently. The wording of the claims is incorporated herein by express reference.

According to the invention, additional depressions are introduced into the underside of the carrier, which extend at least to the webs, ie pass into these. These recesses are preferably wider than the tracks. In the area of these depressions, so to speak, continuous openings are created by the carrier, which are advantageously even wider.

By attaching the depressions from the bottom in the carrier with a greater width than that of the webs, a broadening in the manner of an undercut is formed so to speak in some areas of the webs. However, since such an undercut is not possible when compressing the carrier of insulating material in one step and pressing direction along a single axis, this is achieved by the recesses. Especially when they are wider, undercuts are formed with more space. In these depressions can then be made by pressing the heating element fastened, which will be explained in more detail below. Although then the carrier is in the region of the wells downwards open or the heating elements are exposed down. However, this does not necessarily interfere and can further by other covers or the like. or a backfilling of the recesses are eliminated after the widening of the heating elements.

Advantageously, the recesses are at least 10% wider than the tracks, particularly advantageously significantly wider, so for example 20% to 60%. Thus, sufficient space is created or a sufficiently large undercut under the tracks.

The recesses may, for example, have a round cross-section, in particular be circular. Alternatively, they can also be square or rectangular. Advantageously, they are thus formed in the manner of a blind hole and, as will be explained in more detail below, by pressing a punch or the like. produced during pressing.

The distribution of the depressions is basically freely selectable. Advantageously, such depressions are provided on tight bends or loops of the webs, since a fastening of the heating element against moving out is particularly advantageous here. A distance of the recesses to each other can be several times their diameter, for example 3 to 5 times or even 20 times. The distances can also be regular, but they do not have to be.

The depressions can go at least to half of the carrier, advantageously even deeper. Particularly advantageously, they reach between 60% and 90% into the carrier.

The tracks for the heating elements can go at least 30% deep into the carrier, but advantageously more. For example, the webs can go between 40% and 80% in the carrier so that a heating element is below its top. In connection with the above-described depth of the depressions, so to speak, a kind of overlap should be present, so that the space formed by the undercut is not completely below the web, but occupies a part or even a majority of it or overlaps it, so to speak. This facilitates the wide pressing of the heating elements in this area, since they then do not have to be much lower in order to expand to the side into the undercut can. The webs may have a known rectangular cross-section.

The carrier is advantageously formed in one piece, namely compressed. In particular, it is produced in a single pressing operation, for which purpose it is particularly advantageous to provide depressions on the webs for producing the undercuts. However, said one-piece design does not exclude that additional parts can be attached to the carrier, for example, a cover on the bottom for electrical insulation or further thermal insulation.

Advantageously, a cover plate made of micanite may be provided in an embodiment of the invention in a said carrier or a heater on the top, which has approximately the size of the heater or at least the area covered by the heating elements. This cover plate can serve for electrical insulation upwards. If a named heater should not work as a radiant heater with high power, but for example as a warming radiator with temperatures below 200 ° C, it has surprisingly been found in the context of this additional and independent invention that such a cover plate hardly bothers the heat transfer or at most temporally delayed a little.

The carrier may be formed in a further embodiment of the invention in the manner of a flat plate or a disc. It may have a peripheral edge which projects beyond the heating elements or over the other top side of the carrier. This can represent an advantageous holding option for an aforementioned cover disk. Furthermore, the carrier can be pressed as a finished heater with this edge to the underside of a hob plate.

With such a carrier, an electric heater according to the invention can be provided by the elongated heating elements are placed in the webs and then run it. In the region of the depressions, the heating elements are pressed in width or pushed beyond the width of the webs into the undercuts created by the depressions. So they are held against lifting up, since they are now wider than the train. This wide pressing can advantageously take place in that pressure is exerted on the heating element at least from the top side, for example by a stop.

In this case, a counterstop is brought to the heating element from below in a particularly advantageous manner, so that it is, as it were, pressed wide between the stop and the counterstop. In this case, the counter-stop may be immobile after entering the recess to the underside of the heating element, while the stop presses on the heating element or even hits. A stop for pressing the heating element is advantageously relatively pointed or provided with a narrow edge. So he can advantageously score the heating element or press wide. The counter-attack in turn, is advantageously flat and wide to support the heating element well.

This spreading of the heating elements is particularly advantageous if they consist of coiled heating wire, in particular round-wound heating wire. The narrowness of the spiraling plays a subordinate role. The cross section or the width of the heating elements can be increased by the wide pressing by at least 10%, preferably even by at least 20%. Thus, it is possible to press them across the width of the webs wide for clinging. The normal width of the heating elements is advantageously only slightly less than the width of the webs for easy insertion.

In order to connect the heating elements, it is possible in one embodiment of the invention to pass them through the carrier in a middle region, which is remote from the outer edge, from the upper side to a lower side. For this purpose, a hole may be provided in the carrier. In this case, the heating elements or their connections over the bottom over or are there accessible for electrical contacting and mechanical fastening. For this purpose, electrical connection cables can be brought to the terminals and fixed, for example, welded. Particularly advantageously, a connection of an electrical connection cable to a connection of the heating element takes place very close to the underside of the carrier. Thus, in addition to the electrical connection, a mechanical securing of the connections and of the heating element against movement is formed.

In another embodiment of the invention, the connections of the heating elements can be led away laterally from the carrier. For this purpose, the webs can extend as far as the outer edge of the carrier, so that the heating elements or their connections can be guided outward here and not project upwards beyond the upper side or the aforementioned edge of the carrier. The connections can be, for example be formed as connecting wires on which a round wound heating element is plugged and welded. For their attachment to the carrier they can by holding means such as brackets or the like. be fastened in the outer region of the carrier, for example, be clamped from the top. This makes a simple and mechanically safe connection possible.

In a further embodiment of the invention, as has been mentioned above, such a carrier advantageously made of suitable insulating material, preferably fiber-free and non-ceramic insulating material. From this it is produced by compression, advantageously in a single operation. In a further embodiment of the invention, the carrier may be formed relatively thin, for example, be about 8mm to 15mm thick. The thermal insulation is sufficiently ensured, especially if the finished heater does not cause excessive temperature development. This is the case in particular when the heating device is designed as a so-called heated radiator. This means that in a food preparation, no large energy inputs are possible, but a provided with this heater cooking surface on a hob for keeping warm pots and the food is used. For this purpose, the power of the heating element or the heating device can be between 100 watts and 150 watts, in particular with a power density for the carrier of 0.6 W / cm ² _.

Preferably, the underside of the carrier may be formed substantially flat. Alternatively, it may be provided on its underside at least one protruding attachment region, which is preferably integrally formed, where it may alternatively be attached later, for example, glued. Particularly advantageous two such mounting areas are provided on the underside, which are in particular the same design. Such a mounting area is at least over the underside of the carrier over, possibly over the margin. It serves to fasten the carrier or the electric heating device constructed with it, for example, as a cooking point on a hob under a glass ceramic hob plate. For this purpose, the attachment region has at least one prefabricated opening into which a fastening screw or the like. can be screwed. It is also possible to provide a plurality of such openings in order to allow a different positioning with fine adjustment of the carrier. Such an opening advantageously has such a way away from the carrier that a fastening screw is approximately perpendicular to the plane of the underside of the carrier.

These and other features will become apparent from the claims but also from the description and drawings, wherein the individual features each alone or more in the form of sub-combination in one embodiment of the invention and in other areas be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections as well as intermediate headings does not restrict the general validity of the statements made thereunder.

Brief description of the drawings

Fig. 1

eine Ansicht von oben auf einen Träger gemäß der Erfindung ohne weitere Zusatzteile,

Fig. 2

eine Ansicht von unten auf den Träger aus Fig. 1,

Fig. 3

einen Schnitt durch eine Heizeinrichtung mit einem Träger aus Fig. 1 und 2,

Fig. 4

eine starke Vergrößerung eines Ausschnitts der Heizeinrichtung aus Fig. 3 mit breitgedrücktem Heizelement und

Fig. 5

der Ausschnitt aus Fig. 4 in Seitenansicht.

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

Fig. 1

a view from above of a carrier according to the invention without further accessories,

Fig. 2

a view from below of the carrier Fig. 1 .

Fig. 3

a section through a heater with a carrier Fig. 1 and 2 .

Fig. 4

a strong enlargement of a section of the heater Fig. 3 with broad pressed heating element and

Fig. 5

the clipping off Fig. 4 in side view.

Detailed description of the embodiments

In Fig. 1 the carrier 11 according to the invention is shown from above. The plate or disc-like carrier 11 has an upper side 12 and a lower side 13. At the top 12 extends around a slightly raised edge 14. The carrier 11 is made in one piece in a single pressing operation. It consists of commonly used insulating material, possibly with a binder.

On the top 12 tracks 16 are formed, which go slightly deeper than half the thickness of the wearer. The tracks run meandering for a heating element with a few turns. The course may be such that the webs 16 start and end in a central area. There, at least one hole 17 can be seen, which leads at the end of the web 16 through the carrier 11 to its underside 13. Alternatively, the webs 16 may extend to the edge 14 with an edge exit 18, as also exemplified. Here, a heating element or its electrical connection can be led out. On the underside of the webs 16 recesses 19 according to the invention are shown in dashed lines in a round shape. They are provided on the one hand at the turning points of the tracks 16 and at about regular distance in between.

From the bottom view according to Fig. 2 , in turn, the tracks 16 are shown in dashed lines, the distribution of the recesses 19 is again clearly visible. Furthermore, it can be seen just how in the intersection of the webs 16 and recesses 19, an opening passing through the carrier 11 is present. However, this does not bother when used for a holding radiator. Otherwise it would be to provide down another cover or close the wells 19 later.

In Fig. 3 is shown in side section a heater 23 which is constructed with the carrier 11. In the tracks 16 extend the heating elements 24, which consist of coiled heating wire, for example of a FeCrAl alloy. There are two recesses 19 shown, which go up to the tracks 16, as in the enlargements in Fig. 4 and 5 can also be seen. Otherwise, the heating elements 24 run in the tracks 16 and are slightly narrower than these and also do not protrude beyond the top 12.

It can be seen how at least one connection 26 extends through the hole 17 in the carrier 11 and projects beyond the underside 13. At the hole 17, a connection cable 27 is brought to a projecting beyond the bottom 13 end of the terminal 26 and welded. Thus, not only an electrical contact, but also a mechanical attachment of the terminal 26 against moving back and thus also the heating elements 24 is done. The same thing happens at the other terminal 26.

The magnification in Fig. 4 shows the wide pressing of the heating elements 24. For this purpose, a counter-stop 33 is retracted from below into the recess 19 up to the heating element 24 zoom. Then, a stop 32 presses or hammers from the upper side 12 in the middle on the heating element 24 and presses it wide in this area, so that a notch 29 and especially laterally the widened areas 30 are formed in the upper area. These expand almost to the wall of the recess 19 and thus over the web 16 on, so that a moving out is no longer possible. The stop 32 is not wider than the diameter of the recess 19, so that in the longitudinal direction of the web 16 and only here the heating element 24 is pressed wide.

Out Fig. 4 It can also be seen how the ratio of the penetration depths of the web 16 from the upper side 12 into the carrier 11 to the penetration depth of the depressions 19 from the underside 13 is forth. Namely, they overlap in a wide range or the depression 19 creates an undercut of the web 16.

In Fig. 5 is also shown in the side view, the said overlap, wherein dashed lines to the top of the recess 19 and is shown dotted down to the course of the web 16. In this space, so to speak produced by the overlap, the heating element 24 is pressed or has the widened regions 30, which hold it in the web 16.

The advantage of the free areas formed by the undercuts with the recesses 19 is recognizable mainly in the fact that the widening portions 30 of the heating element 24 do not have to press into the insulating material of the carrier 11, resulting in damage and thus structural, most likely unwanted changes in the carrier 11 leads. They can spread so easily. Otherwise, there would be a risk that the carrier 11 breaks up, in particular, towards its upper side 12 and in turn the mechanical fastening would then be jeopardized.

Claims (17)

1. A support (11) for an electrical heating device (23) for the placing of heating elements (24) on a top side (12) of said support, said heating elements (24) being elongated and running in depressed paths (16) on said top side of said support, said depressed paths being completely open towards said top side (12), in a bottom side (13) of said support additional depressions (19) being made and reaching at least up to said paths (16), characterized in that the depressions (19) are wider than said paths.
2. The support according to claim 1, characterized in that the depressions (19) are at least 10 %, preferably 20 % to 60 % wider than said paths (16).
3. The support according to claim 1 or 2, characterized in that the depressions (19) have a round cross-section, preferably are circular in the type of a blind hole.
4. The support according to any of the preceding claims, characterized in that depressions (19) are provided at narrow bends or loops of the paths (16) and/or the depressions have a mutual spacing which is at least three to five times the diameter thereof.
5. The support according to any of the preceding claims, characterized in that the depth of said depressions (19) is at least 50 % of a thickness of said support (11), preferably between 60 % and 90 %.
6. The support according to any of the preceding claims, characterized in that the depth of said paths is at least 30 % of a thickness of said support (11), preferably between 40 % and 80 %.
7. The support according to any of the preceding claims, characterized in that it is integrally constructed, wherein it is preferably grouted, in particular single grouted.
8. An electrical heating device (23) having a support (11) according to any of the preceding claims, characterized in that elongated heating elements (24) run in said paths (16) which are secured by flattening said heating elements (24) in the vicinity of said depressions (19) over a width of said paths (16) to prevent an upward lifting.
9. The heating device according to claim 8, characterized in that the elongated heating elements (24) are made of coiled round heating wire.
10. The heating device according to claim 8 or 9, characterized in that a cross-section or width of said heating elements (24) is increased by at least 10 % as a result of said flattening, preferably by at least 25 %, wherein in particular the width of the heating elements (24) in a state prior to said flattening is at maximum slightly less than a width of said paths (16).
11. The heating device (23) according to any of the claims 8 to 10, characterized in that terminals (26) of said heating elements (24) in a central area remote from said outer edge (14) of said top side (12) of said support are passed through to said bottom side (13) through said support (11) and can be reached from said bottom side for electrical contacting (27) or mechanical fixing of said terminals (26).
12. The heating device according to claim 11, characterized in that at the bottom side (13) of said support (11) electrical connecting cables (27) are fixed to said terminals (26) for an electrical connection and which fixing brings about a mechanical securing of said terminals against moving back, in particular also securing of said heating element (24), wherein preferably a connection of said electrical connecting cables (27) to said electrical terminals (26) is very close to said support (11).
13. A method for manufacture of a support (11) according to any of the claims 1 to 7, wherein during moulding the support from insulating material on one top side (12) are formed depressed paths (16) for inserting of an elongated heating element (24) and on a bottom side (13) are formed depressions (19) extending at least up to said paths (16), characterized in that the depressions (19) are wider than said paths.
14. A method for manufacture of a heating device (23) according to any of the claims 8 to 12, characterized in that the at least one heating element (24) is inserted from said top side (12) into said paths (16) and subsequently said heating element (24) is sectorally flattened or widened at said depressions (19) by pressure thereon at least from said top side (12), wherein said depressions (19) are wider than said paths.
15. The method according to claim 14, characterized in that pressure is also exerted on said heating element from said bottom side (13), in particular by engagement of a counterstop (33), wherein preferably from the top side (12) pressure is exerted onto the heating element by movement of a stop (32) and from the bottom side (13) said heating element is supported by said counterstop (33).
16. The method according to claim 14 or 15, characterized in that the stop (32) is relatively pointed or has a narrow edge for notching the profile of said heating element (24), wherein said counterstop (33) is flat and wide, preferably somewhat smaller than said depression (19).
17. The method according to any of claims 12 and 14 to 16, characterized in that terminals (26) of said heating element (24) are led away laterally from said support (11), in particular by guiding said paths (16) up to said outer edge of said support (11), and project beyond the side of said support, wherein preferably the terminals (26) are fixed by means of holding means, such as clips or the like, to an outer area of said support (11).

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