WO1997021326A1 - Element chauffant a resistance pour cuiseur - Google Patents

Element chauffant a resistance pour cuiseur Download PDF

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Publication number
WO1997021326A1
WO1997021326A1 PCT/DK1996/000510 DK9600510W WO9721326A1 WO 1997021326 A1 WO1997021326 A1 WO 1997021326A1 DK 9600510 W DK9600510 W DK 9600510W WO 9721326 A1 WO9721326 A1 WO 9721326A1
Authority
WO
WIPO (PCT)
Prior art keywords
heating element
element according
temperature
substrate
conductive film
Prior art date
Application number
PCT/DK1996/000510
Other languages
English (en)
Inventor
Laurent Jeanneteau
Christian Eskildsen
Original Assignee
Aktiebolaget Electrolux
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to AU10308/97A priority Critical patent/AU1030897A/en
Application filed by Aktiebolaget Electrolux filed Critical Aktiebolaget Electrolux
Publication of WO1997021326A1 publication Critical patent/WO1997021326A1/fr

Links

Classifications

    • 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
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • 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
    • H05B3/72—Plates of sheet metal
    • 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
    • H05B2213/00—Aspects relating both to resistive heating and to induction heating, covered by H05B3/00 and H05B6/00
    • H05B2213/07—Heating plates with temperature control means

Definitions

  • a resistive heating element for a cooker A resistive heating element for a cooker.
  • the invention relates to a resistive heating element for a cooker.
  • Traditional heating elements for cookers were constructed with a cast iron top with a spiral groove into which was fitted a lenght of resistor wire protected by a large number of electrically insulating and thermally resistant beads.
  • Thi ⁇ construction was very sturdy but the time constant in heating and cooling i ⁇ today considered much too large.
  • Later designs were constructed as a spiralled tube which was flattened on the top and which had resistor wire embedded inside in a compressed, powdered ceramic ma ⁇ .
  • the manufacture consisted in disposing the wire or wires inside a heat resistant steel tube supported by the powdered ceramic mass and sealed at the ends and subsequently rolled into an essentially triangular profile and bent into a spiral shape which was calibrated in large presses. This construction has a much lower thermal time constant, but it does not lend itself to integration in a flat cooktop.
  • a heating element which does not have the above disadvantages and which is simple to manufacture.
  • a heating element according to the invention which is particular in that it consists of a conductive film applied within a cooking pot defined perimeter to an in ⁇ ulating surface in a thickness and pattern commensurate with the mains voltage and the desired power.
  • the intimate contact with the cooking pot ensure ⁇ that the temperature of the conductive film need not be very high.
  • Thi ⁇ means that several methods of application by e.g. ⁇ creen printing with a high temperature organic binder is feasible.
  • a cooktop fitted with heating elements according to the invention are safer in use because the temperature is everywhere lower than in known cooktop ⁇ , and due to the low thermal intertia a surface safe to the touch is quickly obtained after switchoff .
  • An embodiment of the invention is particular in that the insulating support is in the form of one side of double-sided enamelled metal plate. The plate itself does not have to be very heat resistant since the temperature will not be very high. This means that one may use a simple enamelled steel plate which is very well protected on both sides by the enamel . A typical thickness of the steel is 1 mm.
  • a further embodiment is particular in that the heating side faces down, away from the user. Another embodient combines this with a resistive element used as a temperature sensor is disposed on the upper side. This means that a measurement may automatically be performed in order to control the temperature.
  • a further embodiment is particular in that the metal layer between the two enamel layers is connected to ground. This establishes a very safe construction in that e.g. a short circuit will occur to ground and cause a fuse to blow.
  • a further embodiment is particular in that the material for the conductive film has a positive temperature coefficient. In this way it is obtained that by design a maximum operating temperature cannot be exceeded rather than by extaneous safety components.
  • a further embodiment is particular in that an alumina substrate is used for the heating element. This is a stronger surface than enamel and may be preferred in a configuration where the element is supported in a thermally insulating depression in a solid surface. Alumina has higher thermal conductivity than the embodiments employing enamel. However, the temperature of the substrate will be much lower than in the case of alumina based thick film resistors which are used for dissipating heat by convection.
  • a process for manufacturing a heating element according to the invention is particular in that it comprises the steps of cleaning the surface of the substrate, depositing a paste composed of conductive material in a binder through a screen in a pattern which corresponds to the area to be heated by conduction, drying and firing, optionally with a finishing buffing of the deposited material .
  • the material for the resistive element may be tantalum or a precious metal
  • a further proces ⁇ for the manufacture of a heating element according to the invention is particular in that it comprises the steps of cleaning the surface of the substrate, applying a mask, placing the substrate in a vacuum chamber and sputtering or vacuum depositing a thin film onto the exposed surface.
  • An inventive use of the heating element according to the invention is particular in that it is operated intermittently in two modes, a first mode in which electrical energy i ⁇ ⁇ upplied in order to generate heat, and a second mode in which only a measuring current is supplied in order to obtain a voltage which is indicative of the instantaneous temperature of the bottom of the cooking vessel.
  • a first mode in which electrical energy i ⁇ ⁇ upplied in order to generate heat
  • a second mode in which only a measuring current is supplied in order to obtain a voltage which is indicative of the instantaneous temperature of the bottom of the cooking vessel.
  • use is made of the fact that the heat generated is dissipated very quickly into the load which means that the hotplate very quickly after switchoff will assume the temperature of the bottom of the cooking vessel . In this manner one may dispense with a separate measuring resistive layer.
  • a further inventive use of the heating element according to the invention is particular in that the substrate is laid flush in a depression in a solid top surface and that an O-ring seals the joint between substrate and top surface.
  • Such an O-ring is useful to the ordinary maximum temperature of the heating element according to the invention which i ⁇ 300°C.
  • Fig. 1 shows a heating element from above
  • Fig. 2 shows a a cross section through one embodiment of the invention
  • Fig. 3 shows a heating element fitted in a depression in a cooktop
  • Fig. 4 show ⁇ a block diagram of a control circuit for a heating element according to the invention.
  • a circular area 1 is shown with indications of a meandering conductive layer 2 which constitutes the resistive path which is energized by the electrical power supply. It has turned out that an electrical loading of 8A/mm 2 is practical in use for a cooktop which corresponds to an approximate consumption of e.g. precious metal of lg per kW.
  • Fig. 2 is shown a cross section through a heating element con ⁇ i ⁇ ting of a ⁇ teel plate 3 covered with enamel on the upper side 4 and the lower side 5, with the resistive path 2 on the lower side 5 and the upper side 4 exposed to the cooking utensils.
  • the steel plate 3 is grounded for optimum safety.
  • Fig. 3 shows a heating element (3, 4, 5, 2) fitted into a depres ⁇ ion or well 6 which is formed in a solid cooktop 7 of a concrete-like material.
  • the heating element is sealed by means of a large O-ring 8, and holes in the well 6 are supplied with wires for connecting the heating element to the control switches.
  • Fig. 4 shows a block diagram for a circuit utilizing the property of the heating element of the invention that it has a very small thermal time constant.
  • the resistance 2 acts as a heater when it is connected to the mains.
  • a switch which is indicated by the symbol at 9 disconnects the resistance 2 from the mains and connects it to a measuring and control circuit C instead by means of a timing circuit 12.
  • the measuring and control circuit consists of a measuring current generator 10 and a voltage sensing circuit 11 which monitors the reduction in resistance as the resistor cools down.
  • the slope of the resistance over time (the time derivative of resistance) is stabilizing it can ⁇ afely be a ⁇ sumed that the temperature of the re ⁇ istor 2 is now virtually identical to the temperature of elements in intimate contact with the heating element, i.e. in most cases a cooking ves ⁇ el . If this temperature is higher than or identical to the desired temperature, no reconnection to the main ⁇ i ⁇ performed by the circuit 12.
  • a power controller 14 is included which supplies a lower power than direct connection to the mains, and the cycling of the switch 9 will be lower.
  • the connection between the timing circuit 12 and the power control circuit 14 is not shown in Fig. 4.
  • the connection between the low voltage power supply 13 and the control circuit C as well asd the timer circuit 12 are also not shown.
  • the circuit permits the detection of a no-load condition on the heating element 2, because the time to reach stability of slope is large, and the absolute value of the resistance is high immediately after the switch to the measurement mode. It is immaterial whether the resistor has a definite very large positive temperature coefficient or an average compared to steel or copper. However, for obvious reasons there must be a change of resistance with temperature.

Landscapes

  • Electric Stoves And Ranges (AREA)
  • Resistance Heating (AREA)

Abstract

L'invention porte sur une résistance chauffante pour cuiseur adaptée à la surface occupée par une marmite, consistant en une pellicule conductrice appliquée sur un substrat, une plaque d'acier émaillé, par exemple, incrustée dans une table de cuisson. Cette pellicule conductrice peut également servir de capteur thermique pour agir sur le courant lorsque l'alimentation en énergie électrique est interrompue.
PCT/DK1996/000510 1995-12-04 1996-12-04 Element chauffant a resistance pour cuiseur WO1997021326A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU10308/97A AU1030897A (en) 1995-12-04 1996-11-04 A resistive heating element for a cooker

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK136695 1995-12-04
DK1366/95 1995-12-04

Publications (1)

Publication Number Publication Date
WO1997021326A1 true WO1997021326A1 (fr) 1997-06-12

Family

ID=8104074

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1996/000510 WO1997021326A1 (fr) 1995-12-04 1996-12-04 Element chauffant a resistance pour cuiseur

Country Status (2)

Country Link
AU (1) AU1030897A (fr)
WO (1) WO1997021326A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0789504A3 (fr) * 1996-02-09 1998-01-14 AKO-Werke GmbH & Co. KG Dispositif de mesure de la température pour le circuit de contrÔle d'un radiateur électrique
EP0954201A2 (fr) * 1998-04-27 1999-11-03 White Consolidated Industries, Inc. Elément chauffant sous forme de couche circulaire et table de cuisson en porcelaine-émail
WO2002102215A1 (fr) * 2001-06-14 2002-12-27 Auckland Uniservices Limited Nouveau procede et appareil de cuisson d'aliments
EP1692920B2 (fr) † 2003-11-21 2017-11-22 Watlow Electric Manufacturing Company Système de chauffage multicouche à deux fils
US10557141B2 (en) 2011-07-22 2020-02-11 Basf Plant Science Company Gmbh Plant transformation method

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895216A (en) * 1974-09-30 1975-07-15 Gen Electric Low thermal mass solid plate surface heating unit
GB2072887A (en) * 1980-03-24 1981-10-07 Kenwood Mfg Co Ltd Control of electrical heating elements
DE3302795A1 (de) * 1983-01-28 1984-08-02 Miele & Cie GmbH & Co, 4830 Gütersloh Kochplattenausbildung
DE3545443A1 (de) * 1985-12-20 1987-06-25 Bosch Siemens Hausgeraete Kochstellenheizelement
US4843218A (en) * 1985-12-20 1989-06-27 Bosch-Siemens Hausgerate Gmbh Heating element for thermal heating devices, especially cooking stations
US4855572A (en) * 1987-01-23 1989-08-08 Pace Incorporated Heater for use as either primary or auxiliary heat source and improved circuitry for controlling the heater
EP0384659A2 (fr) * 1989-02-20 1990-08-29 Emaco Ltd. Plaques de cuisinière
EP0579947A1 (fr) * 1992-07-23 1994-01-26 Zanussi Elettrodomestici S.p.A. Machine à laver avec dispositif pour contrôler la température des éléments électriques de chauffage de l'eau
US5313049A (en) * 1990-10-01 1994-05-17 Butagaz Cooking top cover with motorized retractable closure means assembly

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895216A (en) * 1974-09-30 1975-07-15 Gen Electric Low thermal mass solid plate surface heating unit
GB2072887A (en) * 1980-03-24 1981-10-07 Kenwood Mfg Co Ltd Control of electrical heating elements
DE3302795A1 (de) * 1983-01-28 1984-08-02 Miele & Cie GmbH & Co, 4830 Gütersloh Kochplattenausbildung
DE3545443A1 (de) * 1985-12-20 1987-06-25 Bosch Siemens Hausgeraete Kochstellenheizelement
US4843218A (en) * 1985-12-20 1989-06-27 Bosch-Siemens Hausgerate Gmbh Heating element for thermal heating devices, especially cooking stations
US4855572A (en) * 1987-01-23 1989-08-08 Pace Incorporated Heater for use as either primary or auxiliary heat source and improved circuitry for controlling the heater
EP0384659A2 (fr) * 1989-02-20 1990-08-29 Emaco Ltd. Plaques de cuisinière
US5313049A (en) * 1990-10-01 1994-05-17 Butagaz Cooking top cover with motorized retractable closure means assembly
EP0579947A1 (fr) * 1992-07-23 1994-01-26 Zanussi Elettrodomestici S.p.A. Machine à laver avec dispositif pour contrôler la température des éléments électriques de chauffage de l'eau

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0789504A3 (fr) * 1996-02-09 1998-01-14 AKO-Werke GmbH & Co. KG Dispositif de mesure de la température pour le circuit de contrÔle d'un radiateur électrique
EP0954201A2 (fr) * 1998-04-27 1999-11-03 White Consolidated Industries, Inc. Elément chauffant sous forme de couche circulaire et table de cuisson en porcelaine-émail
EP0954201A3 (fr) * 1998-04-27 2000-04-19 White Consolidated Industries, Inc. Elément chauffant sous forme de couche circulaire et table de cuisson en porcelaine-émail
WO2002102215A1 (fr) * 2001-06-14 2002-12-27 Auckland Uniservices Limited Nouveau procede et appareil de cuisson d'aliments
EP1692920B2 (fr) † 2003-11-21 2017-11-22 Watlow Electric Manufacturing Company Système de chauffage multicouche à deux fils
US10557141B2 (en) 2011-07-22 2020-02-11 Basf Plant Science Company Gmbh Plant transformation method

Also Published As

Publication number Publication date
AU1030897A (en) 1997-06-27

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