US20060118102A1 - Cooking system comprising a directly heated glass-ceramic plate - Google Patents
Cooking system comprising a directly heated glass-ceramic plate Download PDFInfo
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- US20060118102A1 US20060118102A1 US10/516,991 US51699105A US2006118102A1 US 20060118102 A1 US20060118102 A1 US 20060118102A1 US 51699105 A US51699105 A US 51699105A US 2006118102 A1 US2006118102 A1 US 2006118102A1
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- cooking
- glass
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- ceramic
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- 238000010411 cooking Methods 0.000 title claims abstract description 163
- 239000002241 glass-ceramic Substances 0.000 title claims abstract description 52
- 238000010438 heat treatment Methods 0.000 claims abstract description 71
- 239000000919 ceramic Substances 0.000 claims abstract description 39
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000006112 glass ceramic composition Substances 0.000 claims abstract description 14
- 239000013078 crystal Substances 0.000 claims abstract description 11
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 9
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 9
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 9
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 9
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 9
- 239000010453 quartz Substances 0.000 claims abstract description 6
- 229910021495 keatite Inorganic materials 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 23
- 229910045601 alloy Inorganic materials 0.000 claims description 13
- 239000000956 alloy Substances 0.000 claims description 13
- 239000007921 spray Substances 0.000 claims description 12
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 10
- 229910001120 nichrome Inorganic materials 0.000 claims description 8
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 7
- 229910052593 corundum Inorganic materials 0.000 claims description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 5
- 229910052878 cordierite Inorganic materials 0.000 claims description 5
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 claims description 5
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 claims description 5
- 229910052863 mullite Inorganic materials 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 238000007650 screen-printing Methods 0.000 claims description 5
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 5
- 229910000684 Cobalt-chrome Inorganic materials 0.000 claims description 4
- 229910000943 NiAl Inorganic materials 0.000 claims description 4
- NPXOKRUENSOPAO-UHFFFAOYSA-N Raney nickel Chemical compound [Al].[Ni] NPXOKRUENSOPAO-UHFFFAOYSA-N 0.000 claims description 4
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 claims description 4
- 239000010952 cobalt-chrome Substances 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 4
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- 230000015556 catabolic process Effects 0.000 claims description 3
- 239000002657 fibrous material Substances 0.000 claims description 3
- 238000010292 electrical insulation Methods 0.000 abstract description 7
- 239000000470 constituent Substances 0.000 abstract 1
- 230000003287 optical effect Effects 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 41
- 239000000463 material Substances 0.000 description 15
- 230000008569 process Effects 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000000853 adhesive Substances 0.000 description 5
- 230000001070 adhesive effect Effects 0.000 description 5
- 238000004140 cleaning Methods 0.000 description 5
- 238000010276 construction Methods 0.000 description 5
- 229910001018 Cast iron Inorganic materials 0.000 description 4
- 229910052581 Si3N4 Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 229910010293 ceramic material Inorganic materials 0.000 description 3
- 239000004020 conductor Substances 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
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- 230000032798 delamination Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000008642 heat stress Effects 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 229910001060 Gray iron Inorganic materials 0.000 description 1
- 229910008556 Li2O—Al2O3—SiO2 Inorganic materials 0.000 description 1
- 229910020413 SiO2—MgO Inorganic materials 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000010062 adhesion mechanism Effects 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000003670 easy-to-clean Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 239000005357 flat glass Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
- C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
- C03C17/3602—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer
- C03C17/3607—Coatings of the type glass/inorganic compound/metal
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
- C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
- C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
- C03C17/3602—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer
- C03C17/3649—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer made of metals other than silver
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
- C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
- C03C17/3602—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer
- C03C17/3655—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer the multilayer coating containing at least one conducting layer
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2217/00—Coatings on glass
- C03C2217/40—Coatings comprising at least one inhomogeneous layer
- C03C2217/425—Coatings comprising at least one inhomogeneous layer consisting of a porous layer
Definitions
- This invention relates to a cooking system based on the principle of heat conduction and has a one-piece cooking surface made of a glass-ceramic material and having at least one cooking zone, which can be individually directly heated by heating elements arranged on an underside of the glass-ceramic plate.
- Cooking systems for cooking food having a cooking surface, arranged level, on which the cooking vessel is located are known.
- the heating arrangement is applied underneath the cooking surface, wherein various function principles of heat transmission are used.
- An optimally tuned cooking system has a level contact between the bottom of the pot and the cooking surface, so that the heat transmission can take place with as little heat loss as possible.
- all surfaces in contact with each other should be arranged in as plan-parallel a manner as possible.
- the temperature gradient between the heating element and the material to be cooked must be sufficiently great for making possible a rapid heating process. Heat losses to the surroundings should be minimized, which can be achieved by an appropriate insulation of the heating element.
- the heating element should be arranged at the least possible distance from the material to be cooked, i.e. directly underneath the cooking surface, while still meeting electrical standards.
- the heat is transferred according to principle of heat conduction.
- the source of the heat is of electrically insulated heating spirals made of resistance wire in the interior of the cooking plate.
- the individual cooking plates are inserted into a mostly metallic cooking surface.
- the cast iron cooking plate is arranged above the cooking surface and, because of thermal expansion, slides on the surface of the support plate during the cooking process. Thermal and mechanical uncoupling of the components is thus achieved. Because of their high-mass construction, these systems behave very sluggish during the pre-cooking process and in their controllability.
- connection is made with heat-resistant adhesives. Electric heating occurs by using layers, through which current flows and which adhere with a solid bond to the cooking plate. Thin layers, which are flat all over, are used, in particular made of SnO, as shown in U.S. Pat. No. 6,037,572. Metal foils are also used as heating elements and are pressed against the substrate, or are connected with the ceramic plate by heat-conducting temperature-resistant adhesives. An electrical insulation between the heating device and the cooking vessel which meets standards is assured by the ceramic plate. With cooking plates made of materials which are electrically conductive, such as SiC, for example, it is possible to install a ceramic insulating plate between the heating device and the cooking plate in order to assure electrical insulation.
- the described construction is distinguished by improved output in the field of pre-cooking process output, efficiency and controllability.
- a temperature gradient during the pre-cooking process can be reduced by the direct contact between the heating element, the cooking plate and the bottom of the pot, and the high degree of heat conductivity of the ceramic plate, without reducing the pre-cooking process output. Heat losses are minimized and thus efficiency of the system is increased. Temperatures in the surface of the cooking zone are reduced to approximately 350° C. The structural height of the cooking plate is also reduced in comparison with cast iron cooking plates.
- the cooking surfaces are made of a material of low heat conductivity and heat expansion, such as, for example, glass-ceramic plates, in particular glass-ceramic plates with components from the Li 2 O—Al 2 O 3 —SiO 2 system, also known by the trademark Ceran®.
- Radiation-heating elements are located underneath the one-piece flat cooking surfaces.
- a glowing resistance wire made of metallic alloys and through which current flows, generates the heating energy. Heat transfer occurs by heat conduction and convection, however, with a proportion of approximately 40% by heat radiation.
- an air gap exists between the bottom of the pot and the cooking surface during the cooking operation, which reduces the transfer of contact heat.
- a drastic drop during the pre-cooking process output is counteracted by the combination of heat radiation and heat conduction.
- the heating element temperature is set to values around 1100° C., so that the system on the cooking zone top has a maximum possible temperature of approximately 570° C.
- the advantage of such systems is an aesthetic appeal created by the appearance of the one-piece level cooking surface.
- a further advantage derived from this arrangement is the ease of cleaning, as well as the free design options by a surface decoration. Because of the lower-mass construction and the reduced heat capacity of the thin glass-ceramic plate, the controllability and the pre-cooking time is reduced in comparison with the cast iron cooking plate.
- the ceramic cooking systems using SiN or SiC are distinguished by high output data. Rapid pre-cooking times and effectiveness of more than 80% are achieved. However, the technical solution causes negative values regarding the esthetic aspects and the ease of cleaning. Cooking output is improved by the use of a cooking plate of high heat conductivity. However, so that heating is locally limited to the cooking zone, a heat barrier between the cooking zone and the remaining cooking surface must be achieved. Thus the one-piece cooking plate is provided with bores, into which ceramic disks are glued. Also, the ceramic disks must protrude slightly above the plane of the cooking surface so that in every case the bottom of the pot rests on the ceramic cooking zone and no air gap is created in the direction of the heating surface. Furthermore, there is an expansion gap filled with adhesive.
- the haptical properties of the cooking surface are inhomogeneous and the ease of cleaning is reduced.
- a cooking zone soiled with food can be cleaned only tediously by mechanical tools, such as sponges or scrapers, because of the protruding ceramic disks and the expansion gap.
- the ceramic cooking zone differs in color from the remainder of the cooking surface, the appearance comes close to the cooking field made of grey cast iron. Thus, the design of the cooking surface becomes less attractive.
- Radiation-heated glass-ceramic cooking fields are built in one piece and thus have a high degree of a pleasing visual appearance and ease of cleaning. No interfering edges and gaps exist.
- the output of such cooking systems in view of pre-cooking, efficiency and controllability must be negatively valued in comparison to Si 3 N 4 cooking systems. Because at temperatures starting at 250° C., the glass-ceramic plates become electrically conducting, the heating element must be mounted a defined distance away from the cooking surface in order to achieve the required electric strength of 3750 V.
- the pre-cooking behavior and controllability are worsened by the air gap between the heating device and the cooking surface. It is necessary to generate high temperatures of more than 1100° C. in the heat conductor for achieving a sufficient pre-cooking output.
- European Patent Reference EP 0 861 014 A1 describes a cooking plate wherein a glass-ceramic plate is heated by metallic conductors directly printed onto it. The electrical insulating layer between the glass-ceramic plate and the heating element, which for meeting standards is absolutely necessary, is not taught.
- European Patent Reference EP 0 866 641 A2 teaches a one-piece glass-ceramic plate and, as with the Si 3 N 4 system, heating takes place by heating elements directly applied to the underside. The technical conversion is accomplished by pressing or gluing on a metal foil, which is then electrically heated. The low maximum cooking temperature which can be achieved by this is disadvantageous. In tests it has been found that simply pressing on a foil heating element causes a strong reduction of the pre-cooking output. A chemical bond or at least a flat mechanical tooth connection is necessary. All commercial adhesives having good heat conduction do not permit their use at temperatures greater than 350° C.
- temperatures around 550° C. are required for achieving a pre-cooking output in connection with a glass-ceramic substrate with direct heating, which is required for the rapid frying of food.
- the reason for this is the low heat conductivity of glass-ceramic materials (1 to 2 W/mK) in comparison with SiN ceramic cooking plate (20 to 30 W/mK).
- the temperature at the heating element is approximately 400° C.
- temperatures around 550° C. are necessary for achieving an equivalent output.
- a further problem is the different thermal expansion between glass-ceramic material (approximately 0 to 1.5 ⁇ 10 ⁇ 6 /K) and metal heating elements (greater than 10 ⁇ 10 ⁇ 6 /K).
- No adhesive which is stable up to 550° C. and has good heat conduction with sufficient ductility for compensating heat expansion can be technically realized.
- a solid bond between the heating element and the insulated glass-ceramic substrate occurs in that an electrical insulating layer is located between the glass-ceramic plate and the heating elements applied in the form of a layer and preferably is of electrically highly-insulating ceramic materials from the material system Al 2 O 3 —SiO 2 —MgO (corundum, quartz, cordierite, mullite).
- PCT International Publication WO 00/15005 describes possibilities for depositing the insulating layer on the low-expanding substrates. Even if the layer bond is mechanically stable, the basic problem still exists, that an arching of the cooking zone occurs when heating the cooking system.
- European Patent Reference EP 0 951 202 A2 describes a directly heatable cooking system with a metallic interlayer, which is grounded for meeting the electrical standard. Thus, occurring excess voltages or leakage currents are drained. However, the structure of such a system is technically difficult to realize and is uneconomical to produce.
- the system output is intended to be improved over conventional cooking systems with heating by way of radiating elements.
- the cooking plate is intended to contain heating zones for the cooking operation, which are individual for the segments, and to assure a plan-parallel arrangement of the bottoms of pots and the cooking plate during cooking operations at temperatures up to 500° C.
- the heating elements of the cooking zone have metallic layers, and between the underside of the glass-ceramic plate a porous ceramic layer is arranged as the electrical insulating layer.
- the cooking surface is of one piece in accordance with the requirements.
- Cooking zones can be distributed on the underside of the glass-ceramic plate by the applied heating elements, which can be operated at different temperatures.
- the low heat conduction capability of the glass-ceramic plate is selected to prevent the heating of the entire cooking surface because of transverse heat conduction.
- the glass-ceramic plate has a low thermal expansion, so that no or only small heat stresses are created during the temperature changes, which could cause the breakage of the glass-ceramic plate. All this is accomplished with materials used for the glass-ceramic plate.
- the layer bond between the heating elements and the underside of the glass-ceramic plate at cooking temperatures of up to 500° C. at the top of the glass-ceramic plate must meet the prescribed standards. If the glass-ceramic plate is electrically conductive, a ceramic layer of Al 2 O 3 , mullite, cordierite, circonium silicate or SiO 2 /TiO 2 is used for electrical insulation between the underside of the glass-ceramic plate and the heating elements.
- the selection of the material and the method for applying the heating elements is such that the heating elements are applied by thermal spray methods, in particular atmospheric plasma spray methods, cold gas spray methods, of NiCr base alloys, NiAl base alloys, CrFeAl base alloys or oxidation-resistant cermets, such as Cr 3 C 2 —NiCr or WC—CoCr, or the heating elements are applied by screen-printing methods from Ag/Pd-containing pastes with a glass frit.
- thermal spray methods in particular atmospheric plasma spray methods, cold gas spray methods, of NiCr base alloys, NiAl base alloys, CrFeAl base alloys or oxidation-resistant cermets, such as Cr 3 C 2 —NiCr or WC—CoCr
- the heating elements are applied by screen-printing methods from Ag/Pd-containing pastes with a glass frit.
- the insulating layer is bonded to the underside of the glass-ceramic plate by thin strips of primary ceramic particles of a width of approximately 50 to 150 nm.
- the heating elements are covered by a thermal insulating layer of silicate fiber materials.
- the required properties of the cooking system are maintained if the glass-ceramic plate has a specific resistance >10 5 ⁇ , and the entire cooking system has a breakdown resistance of >3750 V, while in accordance with the Standard 60335-1 the leakage current is ⁇ 0.25 mA per cooking zone.
- FIG. 1 is a sectional view of a cooking system having a glass-ceramic plate, a ceramic layer, heating elements and thermal protection layer;
- FIG. 2 is an enlarged partial sectional view in a bonding area between the glass-ceramic plate and the ceramic plate as the electrical insulating layer.
- FIG. 1 A cooking system in accordance with this invention is shown in FIG. 1 .
- the glass-ceramic plate 10 forms the cooking surface.
- a ceramic plate 20 which can be provided with nubs for increasing the surface with the glass-ceramic plate 10 , is applied to the underside of the glass-ceramic plate for electrical insulation.
- the layer thicknesses lie between 50 and 350 ⁇ m, in particular in the range between 160 to 200 ⁇ m.
- the insulating layer i.e. the ceramic plate 20 , supports the heating elements 30 which define the cooking zones and which can be individually heated and controlled.
- the heating elements can be embodied in the form of strip conductors or flat heating elements.
- the materials have main crystalline phases of the high quartz mixed crystal or keatite mixed crystals type, mainly formed of the components LiO 2 —Al 2 O 3 —SiO 2 .
- the electrical insulation between the underside 2 of the glass-ceramic plate 10 and the ceramic layer 20 is provided by a layer of a highly insulating ceramic material.
- materials such as Al 2 O 3 , mullite, cordierite, circonium silicate and SO 2 /TiO 2 alloys are proven.
- these materials show a large thermal expansion with values of ⁇ >3 ⁇ 10 ⁇ 6 /K. So that the bonded layer of the glass-ceramic plate 10 and the insulating layer 20 is stable during heating operations, it is necessary, besides good layer adhesion, to simultaneously avoid the appearance of high heat stresses. This is assured by a mechanism based on a chemical adhesion mechanism between the ceramic layer 20 and the glass-ceramic plate 10 and a defined porosity of the ceramic layer material. Young's modulus of the layer is lowered by the porosity, and the layers become quasi-ductile.
- Tests show that the insulating layer 20 does not adhere flat to the underside of the glass-ceramic layer 10 .
- Thin strips of ceramic particles of widths of approximately 50 to 150 nm are formed in the interface, which, as shown, are responsible for the connection shown by the reference numeral 21 in the enlarged partial sectional view in accordance with FIG. 2 .
- This bond which is not flat, reduces the inherent tensions in the system. Delamination of the bonded layer during cooking operations is prevented by this mechanism.
- the heating elements 30 can be applied by screen printing or thermal spraying, in particular atmospheric plasma spray methods or cold gas spray methods.
- the heating elements preferably consist of Ag/Pd-containing pastes with glass frits or, in the case of thermal spray methods, of NiCr base alloys, NiAl base alloys, CrFeAl base alloys or oxidation-resistant cermets, such as Cr 3 C 2 —NiCr or WC—CoCr.
- the chemical bonding of the ceramic layer 20 is created by particle diffusion in the interface ceramic/glass-ceramic material in the area of the strips.
- glass-ceramic materials with main crystalline phases of the high quartz mixed crystal type of the components LiO 2 —Al 2 O 3 —SiO 2 also called LAS glass-ceramic materials, and known under the trademark Ceran®, makes possible the described required chemical bonding to the ceramic layer 20 .
- the cause is the chemical relationship between the glass-ceramic material and the insulating materials that mainly consist of the compositions of SiO 2 and Al 2 O 3 with additions of MgO and TiO 2 . A boundary surface diffusion takes place during chemical bonding.
- a glass-ceramic plate 10 as the cooking surface for the described cooking system combines the one-piece surface of a highly pleasing visual appearance and ease of cleaning with a possibility of the direct application of a permanently durable layer system for heating.
- the provision of high heating output with a simultaneously existing flatness of the cooking zones causes a considerable increase of the cooking output in comparison with conventional cooking systems.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Cookers (AREA)
- Electric Stoves And Ranges (AREA)
- Resistance Heating (AREA)
- Induction Heating Cooking Devices (AREA)
- Surface Treatment Of Glass (AREA)
- Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
Abstract
A cooking system based on the principle of heat conduction and having a one-piece cooking surface made of a glass-ceramic material. The cooking surface has a cooking area which can be directly heated in an individual manner by heating elements placed on the underside of the glass-ceramic plate. The glass-ceramic plate has main crystal phases, high quartz mixed crystal or keatite mixed crystal, primarily formed from constituents LiO2—Al2O3—SiO2, with a coefficient of expansion of α=0 to 1.5×10−6/K, preferably α=0 to 1×10−6/K, and with a thermal conductivity of <3 W/mK, preferably of <2.7 W/m K. The glass-ceramic plate also has at least one cooking area situated on an underside of the plate. In addition, the heating elements of the cooking areas are of metallic layers, and a porous ceramic layer is placed between the underside of the glass-ceramic plate and the heating elements while serving as an electrical insulation layer. The optical appearance and the cleanability of the cooking system are thus improved, and it is possible to directly apply a durable heating layer system while considerably increasing the cooking capacities.
Description
- 1. Field of the Invention
- This invention relates to a cooking system based on the principle of heat conduction and has a one-piece cooking surface made of a glass-ceramic material and having at least one cooking zone, which can be individually directly heated by heating elements arranged on an underside of the glass-ceramic plate.
- 2. Discussion of Related Art
- Cooking systems for cooking food having a cooking surface, arranged level, on which the cooking vessel is located are known. The heating arrangement is applied underneath the cooking surface, wherein various function principles of heat transmission are used. An optimally tuned cooking system has a level contact between the bottom of the pot and the cooking surface, so that the heat transmission can take place with as little heat loss as possible. In the heating state, all surfaces in contact with each other should be arranged in as plan-parallel a manner as possible. The temperature gradient between the heating element and the material to be cooked must be sufficiently great for making possible a rapid heating process. Heat losses to the surroundings should be minimized, which can be achieved by an appropriate insulation of the heating element. The heating element should be arranged at the least possible distance from the material to be cooked, i.e. directly underneath the cooking surface, while still meeting electrical standards.
- In conventional systems with cooking plates made of cast iron, the heat is transferred according to principle of heat conduction. In this case the source of the heat is of electrically insulated heating spirals made of resistance wire in the interior of the cooking plate. The individual cooking plates are inserted into a mostly metallic cooking surface. The cast iron cooking plate is arranged above the cooking surface and, because of thermal expansion, slides on the surface of the support plate during the cooking process. Thermal and mechanical uncoupling of the components is thus achieved. Because of their high-mass construction, these systems behave very sluggish during the pre-cooking process and in their controllability.
- Further development of such cooking systems is achieved by a changed arrangement of the heating elements and a modification of the material of the cooking plate. Thin ceramic disks of good heat conductivity and great mechanical stability, preferably made of non-oxidic ceramic materials, such as Si3N4 or SiC, are used as cooking plates. European Patent References EP 0 853 444 A2 and EP 0 069 298 teach ceramic cooking systems on Si3N4 basis, which have good heat-conducting properties and are very flat. These known cooking plates are inserted into cooking surfaces, preferably of pre-stressed flat glass, but also stone plates or plates made of polymer-ceramic composite materials. To achieve heating of the entire cooking surface, but to counteract mechanical stresses, an expansion gap is provided between the ceramic plate and the cooking surface. The connection is made with heat-resistant adhesives. Electric heating occurs by using layers, through which current flows and which adhere with a solid bond to the cooking plate. Thin layers, which are flat all over, are used, in particular made of SnO, as shown in U.S. Pat. No. 6,037,572. Metal foils are also used as heating elements and are pressed against the substrate, or are connected with the ceramic plate by heat-conducting temperature-resistant adhesives. An electrical insulation between the heating device and the cooking vessel which meets standards is assured by the ceramic plate. With cooking plates made of materials which are electrically conductive, such as SiC, for example, it is possible to install a ceramic insulating plate between the heating device and the cooking plate in order to assure electrical insulation. The described construction is distinguished by improved output in the field of pre-cooking process output, efficiency and controllability. A temperature gradient during the pre-cooking process can be reduced by the direct contact between the heating element, the cooking plate and the bottom of the pot, and the high degree of heat conductivity of the ceramic plate, without reducing the pre-cooking process output. Heat losses are minimized and thus efficiency of the system is increased. Temperatures in the surface of the cooking zone are reduced to approximately 350° C. The structural height of the cooking plate is also reduced in comparison with cast iron cooking plates.
- Alternatively to these systems, radiation-heated systems exist. The cooking surfaces are made of a material of low heat conductivity and heat expansion, such as, for example, glass-ceramic plates, in particular glass-ceramic plates with components from the Li2O—Al2O3—SiO2 system, also known by the trademark Ceran®. Radiation-heating elements are located underneath the one-piece flat cooking surfaces. A glowing resistance wire, made of metallic alloys and through which current flows, generates the heating energy. Heat transfer occurs by heat conduction and convection, however, with a proportion of approximately 40% by heat radiation. When using cooking utensils of lower quality, an air gap exists between the bottom of the pot and the cooking surface during the cooking operation, which reduces the transfer of contact heat. A drastic drop during the pre-cooking process output is counteracted by the combination of heat radiation and heat conduction. The electrical insulation conforming to standards such as EN 60335 and UL 858 between the heating elements and the cooking vessel wherein, when operated at 230 V ac, an electric strength of 3750 V and a leakage current of less than 0.25 mA must be provided during operation, is provided by an air gap. For achieving a sufficient pre-cooking output, the heating element temperature is set to values around 1100° C., so that the system on the cooking zone top has a maximum possible temperature of approximately 570° C. The advantage of such systems is an aesthetic appeal created by the appearance of the one-piece level cooking surface. A further advantage derived from this arrangement is the ease of cleaning, as well as the free design options by a surface decoration. Because of the lower-mass construction and the reduced heat capacity of the thin glass-ceramic plate, the controllability and the pre-cooking time is reduced in comparison with the cast iron cooking plate.
- The ceramic cooking systems using SiN or SiC are distinguished by high output data. Rapid pre-cooking times and effectiveness of more than 80% are achieved. However, the technical solution causes negative values regarding the esthetic aspects and the ease of cleaning. Cooking output is improved by the use of a cooking plate of high heat conductivity. However, so that heating is locally limited to the cooking zone, a heat barrier between the cooking zone and the remaining cooking surface must be achieved. Thus the one-piece cooking plate is provided with bores, into which ceramic disks are glued. Also, the ceramic disks must protrude slightly above the plane of the cooking surface so that in every case the bottom of the pot rests on the ceramic cooking zone and no air gap is created in the direction of the heating surface. Furthermore, there is an expansion gap filled with adhesive. Thus, the haptical properties of the cooking surface are inhomogeneous and the ease of cleaning is reduced. A cooking zone soiled with food can be cleaned only tediously by mechanical tools, such as sponges or scrapers, because of the protruding ceramic disks and the expansion gap. The ceramic cooking zone differs in color from the remainder of the cooking surface, the appearance comes close to the cooking field made of grey cast iron. Thus, the design of the cooking surface becomes less attractive.
- Radiation-heated glass-ceramic cooking fields are built in one piece and thus have a high degree of a pleasing visual appearance and ease of cleaning. No interfering edges and gaps exist. The output of such cooking systems in view of pre-cooking, efficiency and controllability must be negatively valued in comparison to Si3N4 cooking systems. Because at temperatures starting at 250° C., the glass-ceramic plates become electrically conducting, the heating element must be mounted a defined distance away from the cooking surface in order to achieve the required electric strength of 3750 V. The pre-cooking behavior and controllability are worsened by the air gap between the heating device and the cooking surface. It is necessary to generate high temperatures of more than 1100° C. in the heat conductor for achieving a sufficient pre-cooking output. Because the surroundings of the cooking zone are also heated by the heating element, heat losses are created, and the efficiency of the cooking system drops in comparison with ceramic SiN cooking systems from approximately 80% to 60%. The construction with an air gap creates a minimum structural height, which limits the built-in options in a cooking trough. The number of components of a cooking trough with heating elements, including their fixation in place and a control device, is large.
- The construction of an optimized cooking system with a one-piece, visually pleasing cooking surface and improved output data is possible with the direct heating of a glass-ceramic cooking surface.
- European Patent Reference EP 0 861 014 A1 describes a cooking plate wherein a glass-ceramic plate is heated by metallic conductors directly printed onto it. The electrical insulating layer between the glass-ceramic plate and the heating element, which for meeting standards is absolutely necessary, is not taught.
- European Patent Reference EP 0 866 641 A2 teaches a one-piece glass-ceramic plate and, as with the Si3N4 system, heating takes place by heating elements directly applied to the underside. The technical conversion is accomplished by pressing or gluing on a metal foil, which is then electrically heated. The low maximum cooking temperature which can be achieved by this is disadvantageous. In tests it has been found that simply pressing on a foil heating element causes a strong reduction of the pre-cooking output. A chemical bond or at least a flat mechanical tooth connection is necessary. All commercial adhesives having good heat conduction do not permit their use at temperatures greater than 350° C. However, temperatures around 550° C., measured at the heating element, are required for achieving a pre-cooking output in connection with a glass-ceramic substrate with direct heating, which is required for the rapid frying of food. The reason for this is the low heat conductivity of glass-ceramic materials (1 to 2 W/mK) in comparison with SiN ceramic cooking plate (20 to 30 W/mK). With ceramic cooking systems, the temperature at the heating element is approximately 400° C. When using glass-ceramic plates as cooking plates, temperatures around 550° C. are necessary for achieving an equivalent output. A further problem is the different thermal expansion between glass-ceramic material (approximately 0 to 1.5×10−6/K) and metal heating elements (greater than 10×10−6/K). No adhesive, which is stable up to 550° C. and has good heat conduction with sufficient ductility for compensating heat expansion can be technically realized.
- In accordance with one embodiment, a solid bond between the heating element and the insulated glass-ceramic substrate occurs in that an electrical insulating layer is located between the glass-ceramic plate and the heating elements applied in the form of a layer and preferably is of electrically highly-insulating ceramic materials from the material system Al2O3—SiO2—MgO (corundum, quartz, cordierite, mullite). PCT International Publication WO 00/15005 describes possibilities for depositing the insulating layer on the low-expanding substrates. Even if the layer bond is mechanically stable, the basic problem still exists, that an arching of the cooking zone occurs when heating the cooking system. This is created by the different expansion of the glass-ceramic plate and the insulating layer or heating layer (comparable to a bi-metal effect). The air gap being created between the bottom of the pot and the top of the cooking plate lessens the contact surface and considerably reduces the heat transfer. Pre-cooking times worsen dramatically.
- European Patent Reference EP 0 951 202 A2 describes a directly heatable cooking system with a metallic interlayer, which is grounded for meeting the electrical standard. Thus, occurring excess voltages or leakage currents are drained. However, the structure of such a system is technically difficult to realize and is uneconomical to produce.
- It is one object of this invention to provide an electrically directly heatable cooking system of the type mentioned above but which is, along with a visually pleasing appearance, easy to clean. The system output is intended to be improved over conventional cooking systems with heating by way of radiating elements. The cooking plate is intended to contain heating zones for the cooking operation, which are individual for the segments, and to assure a plan-parallel arrangement of the bottoms of pots and the cooking plate during cooking operations at temperatures up to 500° C.
- In accordance with this invention, this object is achieved with the glass-ceramic plate with main crystalline phases of the high quartz mixed crystal or keatite mixed crystal types, mainly of the components LiO2—Al2O3—SiO2, with a coefficient of expansion of α=0 to 1.8×10−6/K, preferably of α=0 to 1.5 10−6/K, and a heat conductivity of <3 W/mK, preferably <2.7 W/mK, and on the underside at least one cooking zone. The heating elements of the cooking zone have metallic layers, and between the underside of the glass-ceramic plate a porous ceramic layer is arranged as the electrical insulating layer.
- In this embodiment, the cooking surface is of one piece in accordance with the requirements. Cooking zones can be distributed on the underside of the glass-ceramic plate by the applied heating elements, which can be operated at different temperatures. The low heat conduction capability of the glass-ceramic plate is selected to prevent the heating of the entire cooking surface because of transverse heat conduction. The glass-ceramic plate has a low thermal expansion, so that no or only small heat stresses are created during the temperature changes, which could cause the breakage of the glass-ceramic plate. All this is accomplished with materials used for the glass-ceramic plate.
- The layer bond between the heating elements and the underside of the glass-ceramic plate at cooking temperatures of up to 500° C. at the top of the glass-ceramic plate must meet the prescribed standards. If the glass-ceramic plate is electrically conductive, a ceramic layer of Al2O3, mullite, cordierite, circonium silicate or SiO2/TiO2 is used for electrical insulation between the underside of the glass-ceramic plate and the heating elements.
- In accordance with one embodiment, the selection of the material and the method for applying the heating elements is such that the heating elements are applied by thermal spray methods, in particular atmospheric plasma spray methods, cold gas spray methods, of NiCr base alloys, NiAl base alloys, CrFeAl base alloys or oxidation-resistant cermets, such as Cr3C2—NiCr or WC—CoCr, or the heating elements are applied by screen-printing methods from Ag/Pd-containing pastes with a glass frit.
- So that the layer adhesion during temperature changes during the heating process remains stable, but high thermal tensions in the material are prevented, in a further embodiment the insulating layer is bonded to the underside of the glass-ceramic plate by thin strips of primary ceramic particles of a width of approximately 50 to 150 nm.
- For a reduction of heat losses the heating elements are covered by a thermal insulating layer of silicate fiber materials.
- The required properties of the cooking system are maintained if the glass-ceramic plate has a specific resistance >105 Ω, and the entire cooking system has a breakdown resistance of >3750 V, while in accordance with the Standard 60335-1 the leakage current is <0.25 mA per cooking zone.
- This invention is described in greater detail in view of an exemplary embodiment represented in the drawings, wherein:
-
FIG. 1 is a sectional view of a cooking system having a glass-ceramic plate, a ceramic layer, heating elements and thermal protection layer; and -
FIG. 2 is an enlarged partial sectional view in a bonding area between the glass-ceramic plate and the ceramic plate as the electrical insulating layer. - A cooking system in accordance with this invention is shown in
FIG. 1 . With a top, the glass-ceramic plate 10 forms the cooking surface. Aceramic plate 20, which can be provided with nubs for increasing the surface with the glass-ceramic plate 10, is applied to the underside of the glass-ceramic plate for electrical insulation. The layer thicknesses lie between 50 and 350 μm, in particular in the range between 160 to 200 μm. The insulating layer, i.e. theceramic plate 20, supports theheating elements 30 which define the cooking zones and which can be individually heated and controlled. - The heating elements can be embodied in the form of strip conductors or flat heating elements.
- The material of the glass-ceramic plate has a heat conductivity <3 W/mK, in particular <2.7 W/mK, and a coefficient of expansion α=0 to 1.8×10−6/K, in particular α=0 to 1.5×10−6/K. The materials have main crystalline phases of the high quartz mixed crystal or keatite mixed crystals type, mainly formed of the components LiO2—Al2O3—SiO2. The electrical insulation between the underside 2 of the glass-
ceramic plate 10 and theceramic layer 20 is provided by a layer of a highly insulating ceramic material. - Thus, materials such as Al2O3, mullite, cordierite, circonium silicate and SO2/TiO2 alloys are proven. However, these materials show a large thermal expansion with values of σ>3×10−6/K. So that the bonded layer of the glass-
ceramic plate 10 and the insulatinglayer 20 is stable during heating operations, it is necessary, besides good layer adhesion, to simultaneously avoid the appearance of high heat stresses. This is assured by a mechanism based on a chemical adhesion mechanism between theceramic layer 20 and the glass-ceramic plate 10 and a defined porosity of the ceramic layer material. Young's modulus of the layer is lowered by the porosity, and the layers become quasi-ductile. - Tests show that the insulating
layer 20 does not adhere flat to the underside of the glass-ceramic layer 10. Thin strips of ceramic particles of widths of approximately 50 to 150 nm are formed in the interface, which, as shown, are responsible for the connection shown by thereference numeral 21 in the enlarged partial sectional view in accordance withFIG. 2 . There is no contact between the glass-ceramic material and the insulation in the area of thepores 22. This bond, which is not flat, reduces the inherent tensions in the system. Delamination of the bonded layer during cooking operations is prevented by this mechanism. Moreover, arching of the glass-ceramic plate 10 in the area of a cooking zone is minimized by the greater expansion of the insulatinglayer 20, so that values <0.2 mm are achieved over the diagonal extension of the cooking zone. It is thus possible to achieve a great cooking performance of the cooking system. - The
heating elements 30 can be applied by screen printing or thermal spraying, in particular atmospheric plasma spray methods or cold gas spray methods. With the screen printing method, the heating elements preferably consist of Ag/Pd-containing pastes with glass frits or, in the case of thermal spray methods, of NiCr base alloys, NiAl base alloys, CrFeAl base alloys or oxidation-resistant cermets, such as Cr3C2—NiCr or WC—CoCr. - The chemical bonding of the
ceramic layer 20 is created by particle diffusion in the interface ceramic/glass-ceramic material in the area of the strips. During tests it was found that alone the use of glass-ceramic materials with main crystalline phases of the high quartz mixed crystal type of the components LiO2—Al2O3—SiO2, also called LAS glass-ceramic materials, and known under the trademark Ceran®, makes possible the described required chemical bonding to theceramic layer 20. The cause is the chemical relationship between the glass-ceramic material and the insulating materials that mainly consist of the compositions of SiO2 and Al2O3 with additions of MgO and TiO2. A boundary surface diffusion takes place during chemical bonding. An exchange of the elements occurs from the side of the glass-ceramic material, as well as the ceramic side. With other material pairings a reaction layer is created in the glass-ceramic material in the interface during diffusion, which has an increased thermal coefficient of expansion. Microscopic tears are formed by the induced stresses, which lead to a lowering of the shock resistance of the total system down to values below the standard requirements. Poor bonding of the layers and a resultant delamination during heating can be observed. In the case of using glass-ceramic materials with higher thermal coefficients of expansion, the described positive effect also occurred. In contrast to LAS glass-ceramic materials, the main crystalline phase is formed as keatite mixed crystals, because of which the thermal coefficient of expansion, inter alia, is increased to approximately α=1.5×10−6/K Thus the expansion difference with theceramic layer 20 is minimized. - Thus, a glass-
ceramic plate 10 as the cooking surface for the described cooking system combines the one-piece surface of a highly pleasing visual appearance and ease of cleaning with a possibility of the direct application of a permanently durable layer system for heating. The provision of high heating output with a simultaneously existing flatness of the cooking zones causes a considerable increase of the cooking output in comparison with conventional cooking systems.
Claims (18)
1. A cooking system using heat conduction and having a one-piece cooking surface made of a glass-ceramic material and having at least one cooking zone which can be individually directly heated by heating elements arranged on an underside of a glass-ceramic plate, the cooking system comprising:
the glass-ceramic plate having main crystalline phases of one of high quartz mixed crystal and keatite mixed crystal type mainly formed of components LiO2—Al2O3—SiO2 with a coefficient of expansion of α=0 to 1.8×10−6/K and a heat conductivity of <3 w/mK, and having at least one cooking zone on the underside,
the heating elements (30) of the cooking zone having metallic layers, and
between the underside (11) of the glass-ceramic plate (10) a porous ceramic layer arranged as an electrical insulating layer (20).
2. The cooking system in accordance with claim 1 , wherein the coefficient of expansion α=0 to 1.5 10 −6/K.
3. The cooking system in accordance with claim 2 , wherein the heat conductivity has a value <2.7 W/mK.
4. The cooking system in accordance with claim 2 , wherein during a cooking operation at 550° C. the cooking zone shows arching in a diagonal direction <0.2 mm.
5. The cooking system in accordance with claim 4 , wherein the heating elements (30) are applied by thermal spray methods, including one of atmospheric plasma spray methods and cold gas spray methods of one of NiCr base alloys, NiAl base alloys, CrFeAl base alloys and oxidation-resistant cermets, including Cr3C2—NiCr or WC—CoCr.
6. The cooking system in accordance with claim 4 , wherein the heating elements (30) are applied by screen printing methods from Ag/Pd-containing pastes with a glass frit.
7. The cooking system in accordance with claim 6 , wherein the ceramic layer used as an insulating layer (20) is of one of Al2O3, mullite, cordierite, circonium silicate and SiO2/TiO2.
8. The cooking system in accordance with claim 7 , wherein the insulating layer (20) is bonded to the underside (11) of the glass-ceramic plate (10) by thin strips (21) of primary ceramic particles of a width of approximately 50 to 150 nm.
9. The cooking system in accordance with claim 8 , wherein the heating elements (30) are covered by a thermal insulating layer (40) of silicate fiber materials.
10. The cooking system in accordance with claim 9 , wherein the glass-ceramic plate (10) has a specific resistance >105 Ω, and the cooking system has a breakdown resistance of >3750 V, and a leakage current is <0.25 mA per cooking zone.
11. The cooking system in accordance with claim 1 , wherein the heat conductivity has a value <2.7 W/mK.
12. The cooking system in accordance with claim 1 , wherein during a cooking operation at 550° C. the cooking zone shows arching in a diagonal direction <0.2 mm.
13. The cooking system in accordance with claim 1 , wherein the heating elements (30) are applied by thermal spray methods, including one of atmospheric plasma spray methods and cold gas spray methods of one of NiCr base alloys, NiAl base alloys, CrFeAl base alloys and oxidation-resistant cermets, including Cr3C2—NiCr or WC—CoCr.
14. The cooking system in accordance with claim 1 , wherein the heating elements (30) are applied by screen printing methods from Ag/Pd-containing pastes with a glass frit.
15. The cooking system in accordance with claim 1 , wherein the ceramic layer used as an insulating layer (20) is of one of Al2O3, mullite, cordierite, circonium silicate and SiO2/TiO2.
16. The cooking system in accordance with claim 1 , wherein the insulating layer (20) is bonded to the underside (11) of the glass-ceramic plate (10) by thin strips (21) of primary ceramic particles of a width of approximately 50 to 150 nm.
17. The cooking system in accordance with claim 1 , wherein the heating elements (30) are covered by a thermal insulating layer (40) of silicate fiber materials.
18. The cooking system in accordance with claim 1 , wherein the glass-ceramic plate (10) has a specific resistance >105 Ω, and the cooking system has a breakdown resistance of >3750 V, and a leakage current is <0.25 mA per cooking zone.
Applications Claiming Priority (3)
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DE10225337.4 | 2002-06-06 | ||
DE10225337A DE10225337A1 (en) | 2002-06-06 | 2002-06-06 | Cooking system with directly heated glass ceramic plate |
PCT/EP2003/005493 WO2003105531A1 (en) | 2002-06-06 | 2003-05-26 | Cooking system comprising a directly heated glass-ceramic plate |
Publications (1)
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US20060118102A1 true US20060118102A1 (en) | 2006-06-08 |
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US10/516,991 Abandoned US20060118102A1 (en) | 2002-06-06 | 2003-05-26 | Cooking system comprising a directly heated glass-ceramic plate |
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US (1) | US20060118102A1 (en) |
EP (1) | EP1516516B1 (en) |
CN (1) | CN100418389C (en) |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120067865A1 (en) * | 2009-03-13 | 2012-03-22 | Friedrich Siebers | Transparent, dyed cooktop |
US20170257909A1 (en) * | 2016-03-02 | 2017-09-07 | Watlow Electric Manufacturing Company | Heater element having targeted decreasing temperature resistance characteristics |
EP3751959A1 (en) * | 2019-06-12 | 2020-12-16 | LG Electronics Inc. -1- | Heating structure and method of manufacturing a surface type heating element |
US11696397B2 (en) * | 2017-07-31 | 2023-07-04 | Apple Inc. | Patterned bonded glass layers in electronic devices |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10356211A1 (en) * | 2003-12-02 | 2005-06-30 | Schott Ag | Heating device, in particular ceramic hob, and method for producing such |
ITMI20041363A1 (en) * | 2004-07-08 | 2004-10-08 | Cedil Sa | HOUSEHOLD APPLIANCES FOR KITCHENS AND SIMILAR |
ES2401890B1 (en) * | 2011-06-29 | 2014-04-10 | BSH Electrodomésticos España S.A. | Home Appliance Device |
WO2013024092A1 (en) * | 2011-08-17 | 2013-02-21 | BSH Bosch und Siemens Hausgeräte GmbH | Overvoltage-protected household appliance device |
CN111698799A (en) * | 2020-05-14 | 2020-09-22 | 佛山市也牛科技有限公司 | Non-metal heating plate for cooking and preparation method and heating device thereof |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3646321A (en) * | 1970-06-22 | 1972-02-29 | Gen Motors Corp | Infrared surface heating unit |
US3733462A (en) * | 1972-01-11 | 1973-05-15 | Raytheon Co | Heating element for flush top ranges |
US4011091A (en) * | 1975-08-13 | 1977-03-08 | Owens-Illinois, Inc. | Ceramic materials containing keatite |
US6037572A (en) * | 1997-02-26 | 2000-03-14 | White Consolidated Industries, Inc. | Thin film heating assemblies |
US6225608B1 (en) * | 1999-11-30 | 2001-05-01 | White Consolidated Industries, Inc. | Circular film heater |
US20030000938A1 (en) * | 2000-12-01 | 2003-01-02 | Yanling Zhou | Ceramic heater, and ceramic heater resistor paste |
US6534751B2 (en) * | 2000-02-28 | 2003-03-18 | Kyocera Corporation | Wafer heating apparatus and ceramic heater, and method for producing the same |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2623684A1 (en) * | 1987-11-24 | 1989-05-26 | Labo Electronique Physique | VITROCERAMIC HEATING ELEMENT |
DE19711541A1 (en) * | 1997-03-20 | 1998-09-24 | Ako Werke Gmbh & Co | Electric hotplate |
DE19814949C2 (en) * | 1997-05-07 | 2002-04-18 | Aeg Hausgeraete Gmbh | Cooking equipment with induction heating and resistance heating |
DE19817194A1 (en) * | 1998-04-17 | 1999-10-21 | Bsh Bosch Siemens Hausgeraete | Cooking plate with electrically conductive ceramic plate |
DK0967838T3 (en) * | 1998-06-25 | 2005-11-28 | White Consolidated Ind Inc | Thin Film Heating Devices |
DE19900178C1 (en) * | 1999-01-07 | 2000-05-25 | Schott Glas | Brittle glass and/or ceramic body for example for a cooking surface, is held in a thermoplastic frame with an elastomer content with a relaxation effect to reduce breakages to minimum levels |
DE19907038C2 (en) * | 1999-02-19 | 2003-04-10 | Schott Glas | Translucent or opaque glass ceramics with high quartz mixed crystals as the predominant crystal phase and their use |
DE29905385U1 (en) * | 1999-03-23 | 2000-08-03 | Schott Glas | Device for the homogeneous heating of glasses and / or glass ceramics with the aid of infrared radiation |
DE10112234C1 (en) * | 2001-03-06 | 2002-07-25 | Schott Glas | Ceramic hob comprises a cooking plate made from glass-ceramic or glass, an electric hot conductor layer, and an insulating layer arranged between the cooking plate and conductor layer |
DE20114002U1 (en) * | 2001-07-14 | 2002-03-07 | Schott Glas | Hob with a glass ceramic plate as the cooking surface |
-
2002
- 2002-06-06 DE DE10225337A patent/DE10225337A1/en not_active Ceased
-
2003
- 2003-05-26 CN CNB038130297A patent/CN100418389C/en not_active Expired - Fee Related
- 2003-05-26 CA CA002488620A patent/CA2488620A1/en not_active Abandoned
- 2003-05-26 AU AU2003237683A patent/AU2003237683A1/en not_active Abandoned
- 2003-05-26 WO PCT/EP2003/005493 patent/WO2003105531A1/en not_active Application Discontinuation
- 2003-05-26 AT AT03735463T patent/ATE317628T1/en not_active IP Right Cessation
- 2003-05-26 EP EP03735463A patent/EP1516516B1/en not_active Expired - Lifetime
- 2003-05-26 US US10/516,991 patent/US20060118102A1/en not_active Abandoned
- 2003-05-26 DE DE50302383T patent/DE50302383D1/en not_active Expired - Lifetime
- 2003-05-26 ES ES03735463T patent/ES2256752T3/en not_active Expired - Lifetime
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3646321A (en) * | 1970-06-22 | 1972-02-29 | Gen Motors Corp | Infrared surface heating unit |
US3733462A (en) * | 1972-01-11 | 1973-05-15 | Raytheon Co | Heating element for flush top ranges |
US4011091A (en) * | 1975-08-13 | 1977-03-08 | Owens-Illinois, Inc. | Ceramic materials containing keatite |
US6037572A (en) * | 1997-02-26 | 2000-03-14 | White Consolidated Industries, Inc. | Thin film heating assemblies |
US6225608B1 (en) * | 1999-11-30 | 2001-05-01 | White Consolidated Industries, Inc. | Circular film heater |
US6534751B2 (en) * | 2000-02-28 | 2003-03-18 | Kyocera Corporation | Wafer heating apparatus and ceramic heater, and method for producing the same |
US20030000938A1 (en) * | 2000-12-01 | 2003-01-02 | Yanling Zhou | Ceramic heater, and ceramic heater resistor paste |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120067865A1 (en) * | 2009-03-13 | 2012-03-22 | Friedrich Siebers | Transparent, dyed cooktop |
US9156727B2 (en) * | 2009-03-13 | 2015-10-13 | Schott Ag | Transparent, dyed cooktop |
US20170257909A1 (en) * | 2016-03-02 | 2017-09-07 | Watlow Electric Manufacturing Company | Heater element having targeted decreasing temperature resistance characteristics |
US10760465B2 (en) * | 2016-03-02 | 2020-09-01 | Watlow Electric Manufacturing Company | Heater element having targeted decreasing temperature resistance characteristics |
US11696397B2 (en) * | 2017-07-31 | 2023-07-04 | Apple Inc. | Patterned bonded glass layers in electronic devices |
EP3751959A1 (en) * | 2019-06-12 | 2020-12-16 | LG Electronics Inc. -1- | Heating structure and method of manufacturing a surface type heating element |
Also Published As
Publication number | Publication date |
---|---|
CN1659928A (en) | 2005-08-24 |
AU2003237683A1 (en) | 2003-12-22 |
CN100418389C (en) | 2008-09-10 |
ATE317628T1 (en) | 2006-02-15 |
CA2488620A1 (en) | 2003-12-18 |
WO2003105531A1 (en) | 2003-12-18 |
EP1516516A1 (en) | 2005-03-23 |
EP1516516B1 (en) | 2006-02-08 |
DE10225337A1 (en) | 2003-12-24 |
ES2256752T3 (en) | 2006-07-16 |
DE50302383D1 (en) | 2006-04-20 |
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