EP0041203B2 - Arrangement for the thermally insulated accommodation of an electrical helical heating element, in particular for a cooking plate heated by radiation and method for its manufacture - Google Patents

Arrangement for the thermally insulated accommodation of an electrical helical heating element, in particular for a cooking plate heated by radiation and method for its manufacture Download PDF

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Publication number
EP0041203B2
EP0041203B2 EP81103958A EP81103958A EP0041203B2 EP 0041203 B2 EP0041203 B2 EP 0041203B2 EP 81103958 A EP81103958 A EP 81103958A EP 81103958 A EP81103958 A EP 81103958A EP 0041203 B2 EP0041203 B2 EP 0041203B2
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European Patent Office
Prior art keywords
layer
insulating
bedding
heat
heating spiral
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EP81103958A
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German (de)
French (fr)
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EP0041203B1 (en
EP0041203A1 (en
Inventor
Hans Kummermehr
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Micropore International Ltd
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Gruenzweig und Hartmann und Glasfaser AG
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
    • H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
    • H05B3/748—Resistive heating elements, i.e. heating elements exposed to the air, e.g. coil wire heater
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/017—Manufacturing methods or apparatus for heaters

Definitions

  • the invention relates to a device for the heat-insulating mounting of an electric heating coil, in particular for a radiation-heated hotplate, according to the preamble of claim 1 and a method which is particularly suitable for its production.
  • the insulation layer based on silica airgel is in this known device as the only heat insulation layer between the heating coil and the bottom of the receptacle made of sheet metal, so that the excellent thermal insulation properties of this special thermal insulation material are optimally utilized .
  • Adequate temperature resistance in the immediate vicinity of the heating coil, which lies directly on the insulation layer, is sought by adding aluminum oxide, which counteracts sintering of the silica airgel at temperatures above about 700 ° C .; aluminum oxide in the form of reinforcing fibers or as an additional admixture can be present in an amount of up to 12% in the insulating material based on silicic acid airgel.
  • Materials for opacifiers are manganese dioxide, titanium dioxide and zirconium oxide.
  • Insulation material of this type has an extremely high thermal resistance, but is not mechanically stable, since it tends to crumble or crumble in the area of already low voltage peaks.
  • DE-B-2339 768 is based on the preamble of claim 1.
  • the shaped body for storing the heating coil can be produced as an inexpensive pressed part which only has to be inserted into the receiving shell, which already contains material of the thermal barrier layer pressed directly against the bottom of the receiving shell.
  • a radiation-heated hotplate is known, the electric heating coil of which is mounted on an insulating support in the form of a disk made of a cardboard-like material, a mechanically perfect and vibration-proof mounting of the electrical heating resistors being ensured on the cardboard-like material.
  • the insulating support formed in this way is in turn mounted on insulating layers or disks, the lower insulating layer in particular being able to have low mechanical strength, for example consisting of a non-or only slightly compressed bulk material, for example finely divided silica.
  • this known device results in the construction with a bottom-side, mechanically less solid, but good thermal insulation layer, for example based on silica airgel, and above that a special mechanically stronger bearing layer for supporting the heating coil.
  • the material of the fixed bearing layer makes only a minor contribution to thermal insulation and thus increases the overall height of the positioning device above the effective thermal barrier layer.
  • the invention has for its object to provide a device of the type specified in the preamble of claim 1, which has both excellent thermal insulation properties with a low overall height, as well as a structurally simple and reliable position securing of the heating coil.
  • the insulation layer can of course also be hardened accordingly, since this increases its mechanical resistance, for example for effective edge protection, albeit at the cost of a slight decrease in thermal insulation capacity; however, since the insulation layer does not need to have the mechanical resistance of the bearing layer, the insulation layer is often not hardened.
  • a base material based on pyrogenic aluminum oxide should be preferred instead of pyrogenic silica, since pyrogenic silica gives somewhat better thermal insulation properties, but material based on aluminum oxide airgel is also considerably more temperature-resistant without additional measures.
  • high-temperature resistant materials such as manganese oxide, titanium oxide or zirconium oxide can be introduced into the insulating material of the bearing layer in order to further increase the temperature resistance if necessary.
  • the device according to the invention thus consists of the receptacle, for example in the form of a sheet metal bowl, the thermal insulation panel to form the thermal insulation material consisting of the insulating layer and the bearing layer, and the heating coil, which is mounted directly on the bearing layer of the thermal insulation panel.
  • the thermal insulation board can be prefabricated in a cost-effective manner, for which purpose one of the layers - the insulation layer or the bearing layer - is pressed from amorphous powder of the desired consistency to achieve pressure fixation, then the material of the other layer is applied and applied to the pre-pressed layer under higher pressure is finished pressed, whereupon the curing can take place with suitable heating.
  • thermal insulation board as a molded part also enables the application of helical grooves to the top of the bearing layer, into which the heating coil can be glued with a high-temperature-resistant inorganic adhesive, as well as a trough-shaped design of this area of the bearing layer with circumferential peripheral edge, without any additional effort. which, due to the mechanical strength of the material of the bearing layer, can directly form the contact surface for the glass ceramic cover of the hotplate, so that a separate spacer ring can be dispensed with in a cost-effective manner.
  • the illustrated device consists essentially of a receptacle 1 made of metal, in particular aluminum sheet, and thermal insulation material in the form of a thermal insulation panel 2, which is arranged on the inside of a peripheral wall 3 of the receptacle 1 between the bottom 4 and a heating coil 5.
  • the electrically operated heating coil 5 has electrical connections, not shown, which are led out of the area of the receiving shell 1 in a suitable manner.
  • the device shown is used for radiant heating of a glass-ceramic cover of a hotplate, the glass-ceramic plate (not shown in detail) resting on a support surface 22 and thus receiving a distance from the upper edge of the peripheral wall 3 of the receiving shell 1 and from the heating coil 5.
  • the device is essentially circular in plan view and is concentric with a central axis 14.
  • the thermal insulation panel 2 consists of an upper bearing layer 7, which receives the heating coil 5 in helical grooves 8.
  • an insulating layer 9 is provided, which abuts the bottom 4 of the receiving shell 1 and consists of fine-pored silica airgel.
  • This material is known per se and, in addition to the silica airgel, generally has a mineral fiber reinforcement and / or an opacifying agent;
  • Such highly effective thermal insulation materials are marketed by the patent owner under the name MINILEIT (registered trademark), whereby for details of the material reference is made to the relevant DE-Osen 2747 663, 2748 307 and 2754 956, to which reference is expressly made.
  • a material for the insulating layer 9 is preferably used, which consists of 30 to 50% fumed silica, 20 to 50% opacifying agent and 5 to 15% aluminum fibers, and is in a density of 200 to 400 kg / m 3 , but not organic or needs to be inorganic hardened.
  • Such a special thermal insulation material has a thermal conductivity that is lower than still air and is also only slightly temperature-dependent.
  • the plates pressed from powdery raw materials made of such a material are mechanically less resistant and difficult to manufacture. For this reason, panels made of this material are usually surrounded by a solid glass fabric during production and subsequently cut to the desired shape.
  • the upper bearing layer 7 consists of an aluminum oxide airgel instead of the silica airgel of the insulation layer 9, or a suitable mixture of both aerogels.
  • Such insulation material based on aluminum oxide airgel is more resistant to higher temperatures than on the basis of silica airgel.
  • the bearing layer 7 can contain additives to high-temperature-resistant materials such as manganese oxide, zirconium oxide or titanium oxide, if required, to further increase the temperature resistance.
  • the material of the bearing layer 7 is hardened with an inorganic binder, for example with suitable glass-forming substances, as is known per se from the earlier patent application EP-A-0 027 264 (prior art according to Art.
  • the material of the bearing layer 7 has only slightly poorer thermal insulation properties than that of the insulating layer 9, but is mechanically considerably stronger and more resistant, so that securing the position of the heating coil 5 directly on the bearing layer 7 no longer poses any problems.
  • metal wire clips holding the heating coil 5 could be inserted into the material of the bearing layer 7, the grooves 8 not being absolutely necessary, but it is preferred to fix the heating coil 5 in helical grooves 8 by means of a high-temperature-resistant inorganic adhesive 6, adhesive with a Temperature resistance up to 1 150 ° C, so completely sufficient, are available.
  • the bearing surfaces 22 can be formed directly on the upper side of a peripheral edge 10, which in the illustrated manner surrounds a trough in the bearing layer 7 for receiving the heating coil 5 on the circumference and thus radiates heat to the peripheral wall 3 of the receiving shell 1 safely avoids.
  • the material in the upper end area 11 of the peripheral edge 10 can be additionally compressed.
  • the thermal insulation board 2 from the lower insulation layer 9 and the upper bearing layer 7 together with grooves 8 and peripheral edge 10 with a bearing surface 22 can be produced as a one-piece pressed part.
  • the powdery material of one of the layers 7 or 9 is first introduced into a press mold and pre-pressed for fixing the pressure, the pressure should be below 25 bar and a pressure of 15 to 20 bar being preferred; good results were obtained at a pressure of 18 bar.
  • the material of the other layer 9 or 7 is added and the blank for the entire thermal insulation board 2 is pressed in one go under a higher pressure of more than 25 bar, in particular at a pressure between 25 and 40 bar; good results were achieved with a pressure of 30 bar.
  • the bearing layer 7 is first pressed in the reverse position and remains in this position for the final pressing.
  • the blank for the thermal insulation board 2 is expediently pressed in the position turned over relative to the operating position, since then an easier filling of the relief-like bottom of the press chamber is possible, which corresponds to the negative of the bearing trough of the bearing layer 7 for the heating winding 5.
  • the edge stamp for the recompression then presses against the support surface 22 on the blank from below.
  • the finished thermal insulation panel 2 can be removed at about 700 ° for 20 to 30 minutes.
  • the molded body forming the thermal insulation board 2 has sufficient stability due to the hardening of the bearing layer 7, the more susceptible free edge of the insulating layer 9 being protected against breakage by the rounding corresponding to the rounding between the peripheral wall 2 and the bottom 4 of the receiving shell 1. Therefore, the thermal insulation board 2 can be shipped and assembled without great risk of damage, and is of course tradable independently. Two concrete examples are given below for the material of the bearing layer 7 or the insulating layer 9.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Thermal Insulation (AREA)
  • Resistance Heating (AREA)

Abstract

1. Device for the heat-insulating bedding of an electrical heating spiral, especially for a radiation-heated cooking plate, with a tray (1) for heat-insulating material arranged between the heating spiral (5) and the bottom (4) of the tray (1), which material comprises, on the bottom side, a highly effective insulating layer (9) of finely porous pyrogenic silica aerogel, in particular with mineral fibre reinforcement and/or opacifiers, and a bedding layer (7) for the heating spiral located between the heating spiral (5) and the insulating layer (9), which bedding layer is of different consistency from the insulating layer (9), characterized in that the bedding layer consists of microporous, particulate insulating material produced by flame pyrolysis, the insulating material being hardened by an inorganic binder and preferably also has a mineral fibre reinforcement and/or opacifiers.

Description

Die Erfindung betrifft eine Vorrichtung zur wärmedämmenden Lagerung einer elektrischen Heizwendel, insbesondere für eine strahlungsbeheizte Kochplatte, nach dem Oberbegriff des Anspruchs 1 und ein zu ihrer Herstellung besonders geeignetes Verfahren.The invention relates to a device for the heat-insulating mounting of an electric heating coil, in particular for a radiation-heated hotplate, according to the preamble of claim 1 and a method which is particularly suitable for its production.

Bei einer Vorrichtung gemäß der DE-A-2806 367 ist die Dämmschicht auf der Basis von Kieselsäureaerogel ist bei dieser bekannten Vorrichtung als einzige Wärmedämmschicht zwischen der Heizwendel und dem Boden der Aufnahmeschale aus Blech eingebracht, so daß die ausgezeichneten Wärmedämmeigenschaften dieses speziellen Wärmedämmaterials optimal ausgenutzt werden. Eine ausreichende Temperaturbeständigkeit in unmittelbarer Nachbarschaft der Heizwendel, die direkt auf der Dämmschicht aufliegt, wird durch Zusatz von Aluminiumoxid angestrebt, welches einem Sintern des Kieselsäureaerogels bei Temperaturen über etwa 700 °C entgegenwirkt; dabei kann Aluminiumoxid in Form von Verstärkungsfasern oder als zusätzliche Beimischung in einer Menge bis zu 12 % in dem Dämmaterial auf der Basis von Keiselsäureaerogel enthalten sein. Die Verwendung ausschließlich des Materials der hochwirksamen Dämmschicht als Wärmedämmaterial ermöglicht eine ausreichende Wärmedämmung trotz flacher Bauweise. Stoffe für Trübungsmittel sind dabei Mangandioxid, Titandioxid und Zirkonoxid.In a device according to DE-A-2806 367, the insulation layer based on silica airgel is in this known device as the only heat insulation layer between the heating coil and the bottom of the receptacle made of sheet metal, so that the excellent thermal insulation properties of this special thermal insulation material are optimally utilized . Adequate temperature resistance in the immediate vicinity of the heating coil, which lies directly on the insulation layer, is sought by adding aluminum oxide, which counteracts sintering of the silica airgel at temperatures above about 700 ° C .; aluminum oxide in the form of reinforcing fibers or as an additional admixture can be present in an amount of up to 12% in the insulating material based on silicic acid airgel. The use of only the material of the highly effective insulation layer as thermal insulation material enables adequate thermal insulation despite the flat construction. Materials for opacifiers are manganese dioxide, titanium dioxide and zirconium oxide.

Dämmaterial dieser Art besitzt zwar einen extrem hohen Wärmedurchleitwiderstand, ist aber mechanisch wenig stabil, da es im Bereich bereits niedriger Spannungsspitzen zu Abbröckelungen oder Abbröselungen neigt.Insulation material of this type has an extremely high thermal resistance, but is not mechanically stable, since it tends to crumble or crumble in the area of already low voltage peaks.

Daher müssen sämtliche Kanten geschützt werden, wozu etwa ein eigener Abstandsring zwischen der Unterfläche der Glaskeramikabdeckung der Kochplatte und der oberen Auflagefläche des Dämmaterials dient. Insbesondere ist die Befestigung der Heizwendel auf diesem Material schwierig. Im Falle der DE-A-2806 367 sind hierzu Metalldrahtklammern vorgesehen, die in das Dämmaterial eingesteckt sind. Durch das Arbeiten der Heizwendel im Betrieb lockern sich diese Metalldrahtklammern jedoch bereits nach wenigen Aufheizzyklen und können so keine ausreichende Verankerung bilden.Therefore, all edges must be protected, for which purpose a separate spacer ring between the lower surface of the glass ceramic cover of the hotplate and the upper contact surface of the insulating material is used. In particular, the attachment of the heating coil on this material is difficult. In the case of DE-A-2806 367, metal wire clips are provided for this purpose, which are inserted into the insulating material. By working the heating coil during operation, these metal wire clips loosen after only a few heating cycles and cannot form an adequate anchorage.

Daher ist es etwa aus der DE-B-2339 768 oder den DE-A 2551 137 und 2744 079 auch bereits bekannt geworden, besondere Lagereinrichtungen für die Heizwendel an der Oberseite der Dämmschicht vorzusehen, so daß die Dämmschicht zumindest nicht alleine die Lagerkräfte aufnehmen muß. Wenn eine wirklich zuverlässige Lagesicherung der Heizwendel erzielt werden soll, so muß hierfür konstruktiv erheblicher Aufwand getrieben werden. Die DE-B-2339 768 liegt dem Obergegriff des Anspruchs 1 zugrunde.Therefore, it has also become known, for example from DE-B-2339 768 or DE-A 2551 137 and 2744 079, to provide special storage devices for the heating coil on the top of the insulation layer, so that the insulation layer does not at least have to absorb the bearing forces alone . If a really reliable position securing of the heating coil is to be achieved, this requires considerable design effort. DE-B-2339 768 is based on the preamble of claim 1.

Gemäß der älteren Patentanmeldung EP-A-0 035 280 (Stand der Technik gemäß Art. 54(3) EPÜ) ist daher auch schon vorgeschlagen worden, die Dämmschicht auf der Basis von feinporigem Kieselsäureaerogel nur im Bodenbereich der Aufnahmeschale vorzusehen und darüber einen Formkörper aus temperaturbeständigem und insbesondere mechanisch festen Material, etwa mit anorganischem Kleber gebundenes Aluminiumsilikat, zur sauberen Lagerung der Heizwendel vorzusehen. Dieses Material besitzt jedoch eine schlechtere Wärmedämmung, so daß sich gegenüber einer Verwendung von ausschließlich dem Materiai der Dämmschicht die Bauhöhe der Vorrichtung etwas vergrößen. Dafür kann der Formkörper zur Lagerung der Heizwendel als billiges Preßteil hergestellt werden, welches nur in die Aufnahmeschale eingesetzt werden muß, die bereits unmittelbar gegen den Boden der Aufnahmeschale verpreßtes Material der Wärmedämmschicht enthält. Hierbei ist allerdings wieder relativ aufwendig, das Material der bodenseitigen Dämmschicht in einem Umfangsrand über die Ebene der Heizwendel nach oben zu ziehen, was anzustreben ist, wenn auch am Umfangsrand der Heizwendel eine entsprechend gute Wärmedämmung erfolgen soll, um eine Aufheizung des Randes der Aufnahmeschale zu vermeiden.According to the older patent application EP-A-0 035 280 (state of the art according to Art. 54 (3) EPC), it has therefore already been proposed to provide the insulating layer on the basis of fine-pored silica airgel only in the bottom region of the receiving shell and to form a molded body above it Temperature-resistant and in particular mechanically stable material, such as aluminum silicate bonded with inorganic adhesive, for the clean storage of the heating coil. However, this material has poorer thermal insulation, so that the overall height of the device increases somewhat compared to the use of only the material of the insulating layer. For this purpose, the shaped body for storing the heating coil can be produced as an inexpensive pressed part which only has to be inserted into the receiving shell, which already contains material of the thermal barrier layer pressed directly against the bottom of the receiving shell. Here, however, it is again relatively expensive to pull the material of the bottom-side insulation layer upwards in a peripheral edge above the level of the heating coil, which should be aimed at if a correspondingly good thermal insulation should also take place on the peripheral edge of the heating coil in order to heat the edge of the receiving shell avoid.

Ähnlich ist aus der DE-A-2729 930 eine strahlungsbeheizte Kochplatte bekannt, deren elektrische Heizwendel auf einem Isolierträger in Form einer Scheibe aus einem pappeähnlichen Material gelagert ist, wobei auf dem pappeähnlichen Material eine mechanisch einwandfreie und erschütterungsfeste Lagerung der elektrischen Heizwiderstände gewährleistet ist. Der so gebildete Isolierträger wiederum ist auf Isolierschichten oder -scheiben gelagert, wobei insbesondere die untere Isolierschicht geringe mechanische Festigkeit besitzen kann, beispielsweise aus einem nicht oder nur schwach verdichteten Schüttmaterial, etwa fein verteilter Kieselsäure bestehen kann. Insgesamt ergibt sich somit bei dieser bekannten Vorrichtung der Aufbau mit einer bodenseitigen, mechanisch wenig festen, dafür gut wärmedämmenden Schicht beispielsweise auf der Basis von Kieselsäureaerogel, und darüber einer speziellen mechanisch festeren Lagerschicht zur Abstützung der Heizwendel. Auch hier aber leistet das Material der festen Lagerschicht einen nur untergeordneten Beitrag zur Wärmedämmung und vergrößert so über der wirksamen Wärmedämmschicht die Bauhöhe der Lagevorrichtung.Similarly, from DE-A-2729 930 a radiation-heated hotplate is known, the electric heating coil of which is mounted on an insulating support in the form of a disk made of a cardboard-like material, a mechanically perfect and vibration-proof mounting of the electrical heating resistors being ensured on the cardboard-like material. The insulating support formed in this way is in turn mounted on insulating layers or disks, the lower insulating layer in particular being able to have low mechanical strength, for example consisting of a non-or only slightly compressed bulk material, for example finely divided silica. Overall, this known device results in the construction with a bottom-side, mechanically less solid, but good thermal insulation layer, for example based on silica airgel, and above that a special mechanically stronger bearing layer for supporting the heating coil. Here too, however, the material of the fixed bearing layer makes only a minor contribution to thermal insulation and thus increases the overall height of the positioning device above the effective thermal barrier layer.

Demgegenüber liegt der Erfindung die Aufgabe zugrunde, eine Vorrichtung der im Oberbegriff des Anspruchs 1 angegebenen Gattung hierfür zu schaffen, die sowohl über ausgezeichnete Wärmedämmeigenschaften bei geringer Bauhöhe verfügt, ais auch eine konstruktiv einfache und zuverlässige Lagesicherung der Heizwendel gewährleistet.In contrast, the invention has for its object to provide a device of the type specified in the preamble of claim 1, which has both excellent thermal insulation properties with a low overall height, as well as a structurally simple and reliable position securing of the heating coil.

Die Lösung dieser Aufgabe ergibt sich durch die kennzeichnenden Merkmale des Anspruchs 1.This object is achieved by the characterizing features of claim 1.

Damit wird eine zweischichtige Bauweise des Wärmedämmaterials bzw. der das Wärmedämmaterial bildenden, vorgefertigten Wärmedämmplatte erzielt, bei der die untere Dämmschicht auf der Basis von Kieselsäureaerogel in der bekannten Weise für eine maximale Wärmedämmung auf engstem Raum genutzt wird, während die obere Lagerschicht demgegenüber nur geringfügig abfallende Wärmedämmeigenschaften aufweist. Dafür aber ist jedenfalls die obere Lagerschicht gehärtet, wozu zur Erzielung einer Hochtemperaturbeständigkeit ein anorganisches Bindemittel verwendet wird. Eine solche Härtung von feindispersen, in der Flammenpyrolyse hergestellten, mikroporösen Isoliermateralien als Grundstoff, der in der Regel mit Mineralfasern verstärkt ist und ein Trübungsmittel wie insbesondere Ilmenit aufweist, ist in der älteren Patentanmeldung EP-A-0 027 264 (Stand der Technik gemäß Art. 54(3) EPÜ) vorgeschlagen worden, wobei auch temperaturbeständige anorganische Bindemittel, bevorzugt etwa glasbildende Stoffe eingesetzt werden; auf diese ältere Anmeldung wird wegen weiterer Einzelheiten insoweit ausdrücklich Bezug genommen. Aus der EP-A-0 027 264 ist auch bereits ein mehrschichtiger Wärmeisolierkörper auf der Grundlage von Kieselsäure - oder Aluminiumoxidaerogel bekannt, dessen Schichten unterschiedlich gehärtet sind. Bei Bedarf kann dabei natürlich auch die Dämmschicht entsprechend gehärtet werden, da hierdurch deren mechanische Widerstandsfähigkeit etwa für einen wirkungsvollen Kantenschutz erhöht wird, wenn auch auf Kosten eines allerdings geringfügigen Abfalles der Wärmedämmfähigkeit; da jedoch die Dämmschicht nicht die mechanische Widerstandsfähigkeit der Lagerschicht zu besitzen braucht, wird man die Dämmschicht häufig nicht härten.This results in a two-layer construction of the thermal insulation material or the prefabricated thermal insulation board forming the thermal insulation material, in which the lower insulating layer based on silica airgel is used in the known manner for maximum thermal insulation in a confined space, while the upper bearing layer, on the other hand, only drops slightly Has thermal insulation properties. However, the upper bearing layer is hardened for this purpose, for which purpose an inorganic binder is used to achieve high-temperature resistance. Such hardening of finely dispersed, microporous insulating materials produced in flame pyrolysis as a base material, which is usually reinforced with mineral fibers and has an opacifying agent such as, in particular, ilmenite, is described in the earlier patent application EP-A-0 027 264 (prior art according to Art 54 (3) EPC), whereby temperature-resistant inorganic binders, preferably glass-forming substances, are also used; this older application is expressly referred to for further details. From EP-A-0 027 264 a multilayered heat insulating body based on silica or aluminum oxide airgel is already known, the layers of which are hardened differently. If necessary, the insulation layer can of course also be hardened accordingly, since this increases its mechanical resistance, for example for effective edge protection, albeit at the cost of a slight decrease in thermal insulation capacity; however, since the insulation layer does not need to have the mechanical resistance of the bearing layer, the insulation layer is often not hardened.

Für die Lagerschicht ist jedoch ein Grundmaterial auf der Basis von pyrogenem Aluminumoxid anstelle von pyrogener Kieselsäure zu bevorzugen, da pyrogene Kieselsäure zwar noch etwas bessere Wärmedämmeigenschaften ergibt, Material auf der Basis von Aluminiumoxid-Aerogel aber auch ohne weitere zusätzliche Maßnahmen erheblich temperaturbeständiger ist. Zusätzlich können in das Isoliermaterial der Lagerschicht hochtemperaturbeständige Materialien wie Manganoxid, Titanoxid oder Zirkonoxid eingeführt werden, um die Temperaturbeständigkeit bei Bedarf weiter zu erhöhen.For the bearing layer, however, a base material based on pyrogenic aluminum oxide should be preferred instead of pyrogenic silica, since pyrogenic silica gives somewhat better thermal insulation properties, but material based on aluminum oxide airgel is also considerably more temperature-resistant without additional measures. In addition, high-temperature resistant materials such as manganese oxide, titanium oxide or zirconium oxide can be introduced into the insulating material of the bearing layer in order to further increase the temperature resistance if necessary.

Die erfindunsgemäße Vorrichtung besteht somit aus der Aufnahmeschale beispielsweise in Form eines Blechnapfes, der Wärmedämmplatte zur Bildung des aus Dämmschicht und Lagerschicht bestehenden Wärmedämmaterials und der Heizwendel, die unmittelbar an der Lagerschicht der Wärmedämmplatte gelagert ist. Die Wärmedämmplatte kann in kostengünstiger Weise vorgefertigt werden, wozu gemäß Anspruch 9 eine der Schichten - die Dämmschicht oder die Lagerschicht - aus amorphem Pulver der gewünschten Konsistenz zur Erzielung einer Druckfixierung vorgepreßt, sodann das Material der anderen Schicht aufgebracht und mit der vorgepreßten Schicht unter höherem Druck fertiggepreßt wird, worauf die Aushärtung unter geeigneter Wärmeeinwrkung erfolgen kann. Dadurch entsteht eine einstückige Wärmedämmplatte, die eine innige Verbindung der Dämmschicht mit der Lagerschicht durch Verkrallung der Partikel gewährleistet. Da die mechanisch stabile Lagerschicht für die Dämmschicht eine zusätzliche Abstützung bietet, kann die so gebildete zweischichtige Wärmedämmplatte ohne übermäßige Gefahr von Beschädigungen gehandhabt, transportiert und versandt werden, um an gegebenenfalls anderer Stelle in die erfindungsgemäße Vorrichtung eingebaut zu werden. Die Herstellung der Wärmedämmplatte als Preßformteil ermöglicht darüber hinaus ohne jeglichen Zusatzaufwand die Anbringung von wendelförmigen Nuten an der Oberseite der Lagerschicht, in welche die Heizwendel denkbar einfach mit einem hochtemperaturbeständigen anorganischen Kleber eingeklebt werden kann, sowie eine muldenförmige Ausbildung dieses Bereichs der Lagerschicht mit umlaufendem Umfangsrand, der infolge der mechanischen Festigkeit des Materials der Lagerschicht unmittelbar die Auflagefläche für die Glaskeramikabdeckung der Kochplatte bilden kann, so daß ein separater Abstandsring in kostengünstiger Weise entfallen kann.The device according to the invention thus consists of the receptacle, for example in the form of a sheet metal bowl, the thermal insulation panel to form the thermal insulation material consisting of the insulating layer and the bearing layer, and the heating coil, which is mounted directly on the bearing layer of the thermal insulation panel. The thermal insulation board can be prefabricated in a cost-effective manner, for which purpose one of the layers - the insulation layer or the bearing layer - is pressed from amorphous powder of the desired consistency to achieve pressure fixation, then the material of the other layer is applied and applied to the pre-pressed layer under higher pressure is finished pressed, whereupon the curing can take place with suitable heating. This creates a one-piece thermal insulation panel that ensures an intimate connection of the insulation layer with the bearing layer by clawing the particles. Since the mechanically stable bearing layer provides additional support for the insulating layer, the two-layer thermal insulation panel thus formed can be handled, transported and dispatched without excessive risk of damage in order to be installed in the device according to the invention at a different location if necessary. The production of the thermal insulation board as a molded part also enables the application of helical grooves to the top of the bearing layer, into which the heating coil can be glued with a high-temperature-resistant inorganic adhesive, as well as a trough-shaped design of this area of the bearing layer with circumferential peripheral edge, without any additional effort. which, due to the mechanical strength of the material of the bearing layer, can directly form the contact surface for the glass ceramic cover of the hotplate, so that a separate spacer ring can be dispensed with in a cost-effective manner.

Weitere Einzelheiten, Merkmale und Vorteile der Erfindung ergeben sich aus der nachfolgenden Beschreibung einer Ausführungsform anhand der Zeichnung.Further details, features and advantages of the invention result from the following description of an embodiment with reference to the drawing.

Die einzige Figur der Zeichnung zeigt einen Schnitt durch eine erfindungsgemäße Vorrichtung.The only figure in the drawing shows a section through a device according to the invention.

Die veranschaulichte Vorrichtung besteht im wesentlichen aus einer Aufnahmeschale 1 aus Metall, insbesondere Aluminiumblech, und Wärmedämmaterial in Form einer Wärmedämmplatte 2, welche an der Innenseite einer Umfangswand 3 der Aufnahmeschale 1 zwischen deren Boden 4 und einer Heizwendel 5 angeordnet ist. Die elektrisch betriebene Heizwendel 5 weist nicht näher dargestellte elektrische Anschlüsse auf, die auf geeignete Weise aus dem Bereich der Aufnahmeschale 1 herausgeführt sind. Die dargestellte Vorrichtung dient zur Strahlungsbeheizung einer Glaskeramikabdeckung einer Kochplatte, wobei die nicht näher dargestellte Glaskeramikplatte auf einer Auflagefläche 22 aufliegt und damit Abstand vom oberen Rand der Umfangswand 3 der Aufnahmeschale 1 sowie von der Heizwendel 5 erhält. Die Umfangswand 3 der Aufnahmeschale 1 und damit die gesamte Vorrichtung hat in Draufsicht im wesentlichen Kreisform und liegt konzentrisch zu einer Mittelachse 14.The illustrated device consists essentially of a receptacle 1 made of metal, in particular aluminum sheet, and thermal insulation material in the form of a thermal insulation panel 2, which is arranged on the inside of a peripheral wall 3 of the receptacle 1 between the bottom 4 and a heating coil 5. The electrically operated heating coil 5 has electrical connections, not shown, which are led out of the area of the receiving shell 1 in a suitable manner. The device shown is used for radiant heating of a glass-ceramic cover of a hotplate, the glass-ceramic plate (not shown in detail) resting on a support surface 22 and thus receiving a distance from the upper edge of the peripheral wall 3 of the receiving shell 1 and from the heating coil 5. The peripheral wall 3 of the receiving shell 1 and thus the entire The device is essentially circular in plan view and is concentric with a central axis 14.

Die Wärmedämmplatte 2 besteht aus einer oberen Lagerschicht 7, welche in wendelförmigen Nuten 8 die Heizwendel 5 aufnimmt. An der der Heizwendel 5 gegenüberliegenden Seite der Lagerschicht 7 ist eine Dämmschicht 9 vorgesehen, die am Boden 4 der Aufnameschale 1 anliegt und aus feinporigem Kieselsäureaerogel besteht. Dieses Material ist an sich bekannt und weist neben dem Kieselsäureaerogel in aller Regel eine Mineralfaserverstärkung und/oder ein Trübungsmittel auf; solche hochwirksamen Wärmedämm-Materialien werden durch die Patentinhaberin unter der Bezeichnung MINILEIT (eingetr. Warenzeichen) vertrieben, wobei hinsichtlich Einzelheiten des Materials auf die einschlägigen DE-Osen 2747 663, 2748 307 und 2754 956 verwiesen wird, auf die insoweit ausdrücklich Bezug genommen wird. Bevorzugt wird ein Material für die Dämmschicht 9 verwendet, welches aus 30 bis 50 % pyrogener Kieselsäure, 20 bis 50 % Trübungsmittel und 5 bis 15 % Aluminiumfasern besteht, sowie in einem Raumgewicht von 200 bis 400 kg/m3 vorliegt, jedoch nicht organisch oder anorganisch gehärtet zu sein braucht. Ein solches Spezial-Wärmedämmaterial besitzt eine Wärmeleitfähigkeit, die geringer ist als ruhende Luft und darüber hinaus nur wenig temperaturabhängig ist. Allerdings sind die aus pulverförmigen Grundstoffen gepreßten Platten aus einem solchen Material mechanisch wenig widerstandsfähig und schwierig herzustellen. Daher werden Platten aus diesem Material in der Regel im Zuge der Herstellung mit einem festen Glasgewebe umgeben und nachträglich in der gewünschten Form zugeschnitten.The thermal insulation panel 2 consists of an upper bearing layer 7, which receives the heating coil 5 in helical grooves 8. On the side of the bearing layer 7 opposite the heating coil 5, an insulating layer 9 is provided, which abuts the bottom 4 of the receiving shell 1 and consists of fine-pored silica airgel. This material is known per se and, in addition to the silica airgel, generally has a mineral fiber reinforcement and / or an opacifying agent; Such highly effective thermal insulation materials are marketed by the patent owner under the name MINILEIT (registered trademark), whereby for details of the material reference is made to the relevant DE-Osen 2747 663, 2748 307 and 2754 956, to which reference is expressly made. A material for the insulating layer 9 is preferably used, which consists of 30 to 50% fumed silica, 20 to 50% opacifying agent and 5 to 15% aluminum fibers, and is in a density of 200 to 400 kg / m 3 , but not organic or needs to be inorganic hardened. Such a special thermal insulation material has a thermal conductivity that is lower than still air and is also only slightly temperature-dependent. However, the plates pressed from powdery raw materials made of such a material are mechanically less resistant and difficult to manufacture. For this reason, panels made of this material are usually surrounded by a solid glass fabric during production and subsequently cut to the desired shape.

Die obere Lagerschicht 7 besteht aus einem Aluminiumoxid-Aerogel anstelle des KieselsäureAerogels der Dämmschicht 9, oder einer geeigneten Mischung beider Aerogele. Derartiges Isoliermaterial auf der Basis von Aluminiumoxid-Aerogel ist bis höhere Temperaturen beständiger als auf der Basis von Kieselsäure-Aerogel. Darüber hinaus kann die Lagerschicht 7 bei Bedarf zur weiteren Erhöhung der Temperaturbeständigkeit Zuschläge an hochtemperaturbeständigen Stoffen wie Manganoxid, Zirkonoxid oder Titanoxid enthalten. Vor allem aber ist das Material der Lagerschicht 7 mit einem anorganischen Bindemittel, beispielsweise mit geeigneten glasbildenden Stoffen, gehärtet, wie dies an sich aus der älteren Patentanmeldung EP-A-0 027 264 (Stand der Technik gemäß Art. 54(3) EPÜ) bekannt ist, auf die wegen weiterer Einzelheiten im Zusammenhang mit der Härtung derartigen Materials ausdrücklich Bezug genommen wird. Dadurch besitzt das Material der Lagerschicht 7 nur geringfügig schlechtere Wärmedämmeigenschaften als dasjenige der Dämmschicht 9, ist aber mechanisch erheblich fester und widerstandsfähiger, so daß die Lagesicherung der Heizwendel 5 unmittelbar an der Lagerschicht 7 keine Probleme mehr aufwirft. Hierzu könnten beispielsweise die Heizwendel 5 haltende Metalldrahtklammern in das Material der Lagerschicht 7 eingesteckt werden, wobei die Nuten 8 nicht zwangsläufig erforderlich wären, jedoch ist bevorzugt, die Heizwendel 5 in wendelförmigen Nuten 8 mittels eines hochtemperaturbeständigen anorganischen Klebers 6 zu befestigen, wobei Kleber mit einer Temperaturbeständigkeit bis zu 1 150°C, also völlig ausreichend, zur Verfügung stehen.The upper bearing layer 7 consists of an aluminum oxide airgel instead of the silica airgel of the insulation layer 9, or a suitable mixture of both aerogels. Such insulation material based on aluminum oxide airgel is more resistant to higher temperatures than on the basis of silica airgel. In addition, the bearing layer 7 can contain additives to high-temperature-resistant materials such as manganese oxide, zirconium oxide or titanium oxide, if required, to further increase the temperature resistance. Above all, however, the material of the bearing layer 7 is hardened with an inorganic binder, for example with suitable glass-forming substances, as is known per se from the earlier patent application EP-A-0 027 264 (prior art according to Art. 54 (3) EPC) is known, which is expressly referred to for further details in connection with the hardening of such material. As a result, the material of the bearing layer 7 has only slightly poorer thermal insulation properties than that of the insulating layer 9, but is mechanically considerably stronger and more resistant, so that securing the position of the heating coil 5 directly on the bearing layer 7 no longer poses any problems. For this purpose, for example, metal wire clips holding the heating coil 5 could be inserted into the material of the bearing layer 7, the grooves 8 not being absolutely necessary, but it is preferred to fix the heating coil 5 in helical grooves 8 by means of a high-temperature-resistant inorganic adhesive 6, adhesive with a Temperature resistance up to 1 150 ° C, so completely sufficient, are available.

Infolge der Härtung des Materials der Lagerschicht 7 können die Auflageflächen 22 unmittelbar an der Oberseite eines Umfangsrandes 10 ausgebildet werden, der in der veranschaulichten Weise eine Mulde in der Lagerschicht 7 zur Aufnahme der Heizwendel 5 umfangsseitig umgibt und so eine Wärmeabstrahlung zur Umfangswand 3 der Aufnahmeschale 1 hin sicher vermeidet. Zur weiteren Erhöhung der Stabilität des Materials im Bereich der Auflagefläche 22 kann das Material im oberen Endbereich 11 des Umfangsrandes 10 zusätzlich verdichtet sein.As a result of the hardening of the material of the bearing layer 7, the bearing surfaces 22 can be formed directly on the upper side of a peripheral edge 10, which in the illustrated manner surrounds a trough in the bearing layer 7 for receiving the heating coil 5 on the circumference and thus radiates heat to the peripheral wall 3 of the receiving shell 1 safely avoids. To further increase the stability of the material in the area of the bearing surface 22, the material in the upper end area 11 of the peripheral edge 10 can be additionally compressed.

Die Wärmedämmplatte 2 aus der unteren Dämmschicht 9 und der oberen Lagerschicht 7 samt Nuten 8 und Umfangsrand 10 mit Auflagefläche 22 kann als einstückiges Preßteil hergestellt werden. Hierzu wird zunächst das pulverförmige Material einer der Schichten 7 oder 9 in eine Pressenform eingegeben und zur Druckfixierung vorgepreßt, wobei der Druck unter 25 bar liegen sollte und ein Druck von 15 bis 20 bar bevorzugt ist; mit einem Druck von 18 bar wurden gute Ergebnisse erzielt. Sodann wird das Material der anderen Schicht 9 oder 7 zugefügt und der Rohling für die gesamte Wärmedämmplatte 2 in einem Zuge unter einem höheren Druck von mehr als 25 bar fertiggepreßt, insbesondere bei einem Druck zwischen 25 und 40 bar; mit einem Druck von 30 bar hierfür wurden gute Ergebnisse erzielt. Bevorzugt wird zunächst die Lagerschicht 7 in umgekehrter Stellung vorgepreßt und verbleibt für das Fertigpressen in dieser Lage.The thermal insulation board 2 from the lower insulation layer 9 and the upper bearing layer 7 together with grooves 8 and peripheral edge 10 with a bearing surface 22 can be produced as a one-piece pressed part. For this purpose, the powdery material of one of the layers 7 or 9 is first introduced into a press mold and pre-pressed for fixing the pressure, the pressure should be below 25 bar and a pressure of 15 to 20 bar being preferred; good results were obtained at a pressure of 18 bar. Then the material of the other layer 9 or 7 is added and the blank for the entire thermal insulation board 2 is pressed in one go under a higher pressure of more than 25 bar, in particular at a pressure between 25 and 40 bar; good results were achieved with a pressure of 30 bar. Preferably, the bearing layer 7 is first pressed in the reverse position and remains in this position for the final pressing.

Um die Verdichtung des Endbereiches 11 des Umfangsrandes 10 zu erzielen, wird im Zuge der Nachpressung mit einem geeigneten Randstempel, der auf die Auflagefläche 22 wirkt, nachverdichtet, so daß ein zusätzlicher Arbeitsgang hierfür nicht erforderlich ist.In order to achieve the compression of the end region 11 of the peripheral edge 10, in the course of the re-pressing, a suitable edge stamp, which acts on the bearing surface 22, is subsequently compressed, so that an additional operation is not necessary for this.

Zweckmäßig wird der Rohling für die Wärmedämmplatte 2 in gegenüber der Betriebsstellung umgedrehter Stellung gepreßt, da dann eine leichtere Füllung des reliefartigen Bodens der Pressenkammer möglich ist, welcher dem Negativ der Lagermulde der Lagerschicht 7 für die Heizwicklung 5 entspricht. Der Randstempel für die Nachverdichtung drückt dann von unten gegen die Auflagefläche 22 am Rohling.The blank for the thermal insulation board 2 is expediently pressed in the position turned over relative to the operating position, since then an easier filling of the relief-like bottom of the press chamber is possible, which corresponds to the negative of the bearing trough of the bearing layer 7 for the heating winding 5. The edge stamp for the recompression then presses against the support surface 22 on the blank from below.

Nach entsprechender Wärmeeinwirkung durch Wärmestrahlung oder in einem üblichen Ofen bei etwa 700° für 20 bis 30 Minuten kann die fertige Wärmedämmplatte 2 entnommen werden. Zur Montage braucht lediglich der Kleber 6 in die Nuten 8 eingebracht und die Heizwendel 5 eingesetzt werden, wonach die Wärmedämmplatte 2 mit der Heizwendel in die Aufnahmeschale eingesetzt werden kann. Der die Wärmedämmplatte 2 bildende Formkörper besitzt durch die Härtung der Lagerschicht 7 ausreichende Stabilität, wobei die anfälligere freie Kante der Dämmschicht 9 durch die der Rundung zwischen der Umfangswand 2 und dem Boden 4 der Aufnahmeschale 1 entsprechende Rundung bruchgeschützt ist. Daher kann die Wärmedämmplatte 2 ohne große Beschädigungsgefahr versandt und montiert werden, und ist natürlich selbständig handelbar. Für das Material der Lagerschicht 7 bzw. der Dämmschicht 9 sind nachstehend noch zwei konkrete Beispiele zur Veranschaulichung angegeben.After appropriate heat exposure by heat radiation or in a conventional oven The finished thermal insulation panel 2 can be removed at about 700 ° for 20 to 30 minutes. For assembly, only the adhesive 6 needs to be introduced into the grooves 8 and the heating coil 5 inserted, after which the thermal insulation panel 2 with the heating coil can be inserted into the receiving shell. The molded body forming the thermal insulation board 2 has sufficient stability due to the hardening of the bearing layer 7, the more susceptible free edge of the insulating layer 9 being protected against breakage by the rounding corresponding to the rounding between the peripheral wall 2 and the bottom 4 of the receiving shell 1. Therefore, the thermal insulation board 2 can be shipped and assembled without great risk of damage, and is of course tradable independently. Two concrete examples are given below for the material of the bearing layer 7 or the insulating layer 9.

Beispiel 1example 1

Material für die Lagerschicht 7:

  • 58,4 % pyrogene Kieselsäure
  • 20,0 % Ilmenit
  • 8,1 % Al2O3
  • 11,0 % Aluminiumsilikatfaser
  • 2,5 % Härter.
  • Material für die Dämmschicht 9:
  • 59,6 % pyrogene Kieselsäure
  • 34,8 % Ilmenit
  • 5,6 % Aluminiumsilikatfaser.
Material for the bearing layer 7:
  • 58.4% fumed silica
  • 20.0% ilmenite
  • 8.1 % Al 2 O 3
  • 11.0% aluminum silicate fiber
  • 2.5% hardener.
  • Material for the insulation layer 9:
  • 59.6% fumed silica
  • 34.8% ilmenite
  • 5.6% aluminum silicate fiber.

Beispiel 2Example 2

Material für die Lagerschicht 7:

  • 29,2 % pyrogene Kieselsäure
  • 29,2 % pyrogenes Aluminiumoxid
  • 20,0 % Ilmenit
  • 8,1 % Al2O3
  • 11,0 % Aluminiumsilikatfaser
  • 2,5 % Härter.
Material für die Dämmschicht 9 wie Beispiel 1. Die Prozent-Angaben beziehen sich auf Gewichtsprozente in der Rohstoffmischung.Material for the bearing layer 7:
  • 29.2% fumed silica
  • 29.2% fumed alumina
  • 20.0% ilmenite
  • 8, 1% Al 2 O 3
  • 11.0% aluminum silicate fiber
  • 2.5% hardener.
Material for the insulation layer 9 as in example 1. The percentages relate to percentages by weight in the raw material mixture.

Claims (14)

1. Device for the heat-insulating bedding of an electrical heating spiral, especially for a radiation-heated cooking plate, with a tray (1) for heat-insulating material arranged between the heating spiral (5) and the bottom (4) of the tray (1), which material comprises, on the bottom side, a highly effective insulating layer (9) of finely porous pyrogenic silica aerogel, in particular with mineral fibre reinforcement and/or opacifiers, and a bedding layer (7) for the heating spiral located between the heating spiral (5) and the insulating layer (9), which bedding layer is of different consistency from the insulating layer (9), characterised in that the bedding layer consists of microporous, particulate insulating material produced by flame pyrolysis, the insulating material being hardened by an inorganic binder and preferably also has a mineral fibre reinforcement and/or opacifiers.
2. Device according to Claim 1, characterised in that the insulating material of the bedding layer (7) contains or consists of pyrogenic aluminium oxide.
3. Device according to Claim 1 or 2, characterised in that the insulating material of the bedding layer (7) is enriched with highly heat-resistant materials such as in particular manganese oxide, titanium oxide or zirconium oxide.
4. Device according to one of Claims 1 to 3, characterised in that the upper face of the bedding layer (7) has spiral grooves (8) for receiving the heating spiral (5), in which grooves the heating spiral (5) is held by means of a highly heat-resistant inorganic adhesive (6).
5. Device according to one of Claims 1 to 4, characterised in that the bedding layer (7) has an integral peripheral rim (10) projecting beyond the plane of the heating spiral (5).
6. Device according to Claim 5, characterised in that the peripheral rim (10) directly forms, on its upper face, a supporting surface (22) for the conventional vitreous ceramic covering or the like, of the cooking plate.
7. Device according to Claim 5 or 6, characterised in that the peripheral rim (10) is additionally densified in its upper end zone (11).
8. Device according to one of the preceding Claims, characterised in that the heat-insulating material is present in the form of a separate two- layer heat-insulating plate (2).
9. Method for the production of a device according to Claim 8, characterised in that the material of one layer of the heat-insulating plate (2) is pre-compressed and the layer pre-compressed in this way is finally compressed with the material of the other layer under a higher pressure with respect to the precompressing and that the bedding layer of the pressed blank is hardened by the action of heat.
10. Method according to Claim 9, characterised in that the pre-compressed layer is the bedding layer.
11. Method according to Claim 9 or 10, characterised in that the pre-compression takes place at a pressure of less than 25 bars, preferably at 15 to 20 bars, in particular at approximately 18 bars and the final compression takes place at a pressure of more than 25 bars, preferably at 25 to 40 bars, in particular at approximately 30 bars.
12. Method according to one of Claims 9 to 11, characterised in that the peripheral rim is subsequently compressed at increased pressure in the course of the final compression.
13. Method according to one of Claims 9 to 12, characterised in that at the time of final compressing, the bedding layer is located below the insulating layer.
14. Method according to Claims 10 and 13, characterised in that the bedding layer is pre-compressed with a bedding trough pointing downwards and a peripheral rim pointing downwards, then the material for the insulating layer is introduced and this is finally compressed against the upper side of the inverted insulating layer.
EP81103958A 1980-05-29 1981-05-22 Arrangement for the thermally insulated accommodation of an electrical helical heating element, in particular for a cooking plate heated by radiation and method for its manufacture Expired EP0041203B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81103958T ATE9255T1 (en) 1980-05-29 1981-05-22 DEVICE FOR THE HEAT-INSULATING BEARING OF AN ELECTRIC HEATING COIL, IN PARTICULAR FOR A RADIATION-HEATED COOKING PLATE, AND HEAT-INSULATING PLATE FOR THESE AND METHOD FOR THEIR MANUFACTURE.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3020326 1980-05-29
DE3020326A DE3020326C2 (en) 1980-05-29 1980-05-29 Radiant heater with an electrical heating coil, in particular for a glass ceramic hotplate

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Publication Number Publication Date
EP0041203A1 EP0041203A1 (en) 1981-12-09
EP0041203B1 EP0041203B1 (en) 1984-09-05
EP0041203B2 true EP0041203B2 (en) 1988-06-08

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AT (1) ATE9255T1 (en)
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DE3102935A1 (en) * 1981-01-29 1982-09-02 Grünzweig + Hartmann und Glasfaser AG, 6700 Ludwigshafen DEVICE FOR THE HEAT-INSULATING STORAGE OF AN ELECTRIC HEATER, IN PARTICULAR FOR A RADIATION-HEATED COOKING PLATE, AND A HEAT-INSULATING PLATE THEREFOR AND METHOD FOR THE PRODUCTION THEREOF
DE3144661A1 (en) * 1981-11-10 1983-05-19 Wacker-Chemie GmbH, 8000 München HEATING PLATE
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Also Published As

Publication number Publication date
ATE9255T1 (en) 1984-09-15
DE3020326A1 (en) 1981-12-03
DE3020326C2 (en) 1985-12-19
EP0041203B1 (en) 1984-09-05
EP0041203A1 (en) 1981-12-09

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