EP0384640A2 - Plaques chauffantes électriques - Google Patents

Plaques chauffantes électriques Download PDF

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Publication number
EP0384640A2
EP0384640A2 EP90301604A EP90301604A EP0384640A2 EP 0384640 A2 EP0384640 A2 EP 0384640A2 EP 90301604 A EP90301604 A EP 90301604A EP 90301604 A EP90301604 A EP 90301604A EP 0384640 A2 EP0384640 A2 EP 0384640A2
Authority
EP
European Patent Office
Prior art keywords
sections
conductors
groups
resistance
electric hotplate
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP90301604A
Other languages
German (de)
English (en)
Other versions
EP0384640A3 (fr
Inventor
Michael H. Buttery
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electrolux Household Appliances Ltd
Original Assignee
Emaco Ltd
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
Application filed by Emaco Ltd filed Critical Emaco Ltd
Publication of EP0384640A2 publication Critical patent/EP0384640A2/fr
Publication of EP0384640A3 publication Critical patent/EP0384640A3/fr
Withdrawn legal-status Critical Current

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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
    • H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
    • 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
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/013—Heaters using resistive films or coatings
    • 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
    • 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
    • H05B2203/02—Heaters using heating elements having a positive temperature coefficient

Definitions

  • This invention relates to electric hotplates and applies primarily to hotplates for cooking hobs.
  • heating elements consisting of a coil of resistive wire, generally of nichrome, which has a very small temperature co-efficient of restivity.
  • resistive wire generally of nichrome
  • a heating element is made from a material having a positive temperature co-efficient of resistivity.
  • the current flow and, therefore, the power dissipated is greater when the element is cold and reduces as the element reaches its operating temperature.
  • a further problem with such hotplates is that because the resistance of the element is low on switching on, the initial current may be unacceptably large and may cause damage.
  • One particular embodiment of the invention is directed to this problem.
  • An electric hotplate having a heating element comprises a plurality of sections of a material having a positive temperature coefficient of resistivity the sections being connected in parallel in groups, and the groups being connected in series between supply terminals.
  • the element of the hotplate comprises not a single conductor, but sixteen conductive sections R all of a material having a substantial positive temperature co-efficient of resistivity, and all having substantially similar resistance when measured at the same temperature.
  • the sections are connected in four groups of four.
  • the sections in each group are connected in parallel and the groups are connected in series with one another.
  • A represents an input terminal connected for example to an energy regulator.
  • the conductors X, Y and Z connect the elements to connect the respective groups in parallel and B represents an output terminal for connection to the neutral supply line. It will be appreciated that the overall resistance of this assembly is equal to the resistance of any one section.
  • FIG 2 is a diagrammatic section in plan of a hotplate according to the invention.
  • the hotplate is a laminated structure comprising a metal plate coated with a ceramic insulating layer on which are deposited resistance films forming the sections of the heating element and conductive films forming the interconnections,
  • the electrical arrangement is as described above with regard to Figure 1.
  • the resistive sections are composed of a metal/glass mixture, the proportion of metal to glass (typically from 50/50 to 95/5 percent metal/glass) being selected to give a suitable resistivity.
  • Nickel is a particularly suitable metal for use in the resistive sections, although other metals, such as cobalt, and alloys containing nickel and/or cobalt may also be used for this purpose.
  • the conductors are mainly or entirely metallic in composition.
  • the metal and glass are finely powdered and thoroughly mixed in the required proportion with a screen printing medium to produce a viscous ink which can be readily screen printed in the required position on the hotplate.
  • the conductors may be applied by similar means. After screen printing, the printed hotplate is dried at a moderate temperature and is then fired at a high temperature to bind the resistive sections and the conductors to the ceramic substrate. Connections are made to the supply conductors and a further protective layer may be applied.
  • the conductive and resistive pattern is shown in Figure 2.
  • the outermost conductor A and the innermost conductor B are connected to a supply and between them are intervening conducting rings X, Y and Z between which the resistive sections are connected concentrically and in parallel groups. There are four parallel resistive sections between each consecutive pair of conductors. Because of the concentric arrangement, a saucepan partially covering the hotplate will reduce the temperature of some sections in each of the groups and the increased current will be diverted through these cooler sections. Conversely, if a single continuous element were employed, the whole of the increased current would pass through the hottest part of the element, increasing the risk of a burn out in that region.
  • FIGs 3 and 4 Further emebodiments of this invention are shown in Figures 3 and 4.
  • two annular conductors C, D are connected to the sections R by a plurality of radial conductors F, G.
  • Radial conductors F connect each group of four sections R to the outer annular conductor C and radial conductors G connect each group of sections R to the inner annular conductor D.
  • FIG 4 The embodiment shown in Figure 4 is broadly similar to that of Figure 3 but has three annular conductors: outer and inner annular conductors C, D are as before but there is an intermediate annular conductor E.
  • outer and inner annular conductors C, D are as before but there is an intermediate annular conductor E.
  • intermediate annular conductor E there are only two sections R in each group but there are twice as many groups and therefore the number of sections in Figure 4 is the same as that in Figure 3.
  • the groups of sections are split into inner and outer sets by the intermediate annular conductor E.
  • Each group of sections R in the outer set is connected to the outer annular conductor C by radial conductor F, and is also connected to the intermediate annular conductor E by radial conductors H.
  • Each group of sections R in the inner set is connected to the intermediate annular conductor E by radial conductors I, and is also connected to the inner annular conductor D by radial conductors G.
  • annular conductors C, D, E are connected to a suitable supply at terminals T.
  • a suitable supply is suitable for use with an energy regulator and the Figure 4 embodiment is suitable for use with a switched power supply.
  • annular conductors C,D,E need not be situated on the plate but could instead take the form of a wired ring main.
  • the intermediate conductors X, Y and Z or the radial conductors F, G, H and I are made of a material which has a strong negative temperature co-efficient of resistivity, such that its resistance is comparable with that of the heating sections at room temperature but falls to a much smaller value, preferably negligibly low, but at most one-quarter of the resistance of a section at the operating temperature.
  • This modification increases the resistance of the elements appreciably at room temperature and therefore reduces the otherwise objectionably large initial current on first switching on.
  • the embodiment shown in Figures 5 and 6 is of laminated construction similar to that of Figure 2, and includes a spiral arrangement of four conductive sections R.
  • the four conductive sectsions R are connected as shown between outer (F1) and inner (F2) line feeder tracks and an inner neutral feeder track (M1) connected to live and neutral terminals L and M respectively.
  • This embodiment again overcomes localised overheating using conductive sections R made from material possessing a substantial positive temperature coefficient of resistivity and possessing substantially similar resistance when measured at the same temperature.

Landscapes

  • Resistance Heating (AREA)
EP19900301604 1989-02-20 1990-02-15 Plaques chauffantes électriques Withdrawn EP0384640A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8903829A GB2228396A (en) 1989-02-20 1989-02-20 Electric hotplate
GB8903829 1989-02-20

Publications (2)

Publication Number Publication Date
EP0384640A2 true EP0384640A2 (fr) 1990-08-29
EP0384640A3 EP0384640A3 (fr) 1992-03-18

Family

ID=10651990

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900301604 Withdrawn EP0384640A3 (fr) 1989-02-20 1990-02-15 Plaques chauffantes électriques

Country Status (3)

Country Link
EP (1) EP0384640A3 (fr)
JP (1) JPH02247996A (fr)
GB (1) GB2228396A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0573618B1 (fr) * 1991-09-05 1995-02-08 Gabriel Bernaz Dispositif d'epilation electronique a haute frequence
WO1998036618A1 (fr) * 1997-02-17 1998-08-20 Strix Limited Resistances de chauffage electriques
GB2337684A (en) * 1997-02-17 1999-11-24 Strix Ltd Electric heaters
US20170325293A1 (en) * 2016-05-06 2017-11-09 General Electric Company Appliance Heating Element with Integrated Temperature Sensing
US10251218B2 (en) 2015-04-27 2019-04-02 Haier Us Appliance Solutions, Inc. Appliance heating element
US10544722B2 (en) 2016-03-02 2020-01-28 Watlow Electric Manufacturing Company Virtual sensing system

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2296847B (en) * 1994-11-30 1999-03-24 Strix Ltd Electric heaters
GB2307629B (en) * 1995-11-20 2001-01-10 Strix Ltd Electric heaters
GB9816645D0 (en) * 1998-07-30 1998-09-30 Otter Controls Ltd Improvements relating to electrically heated water boiling vessels
GB2340713B (en) * 1998-08-12 2003-03-12 Otter Controls Ltd Improvements relating to electric heating elements

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1102755A (fr) * 1953-06-23 1955-10-25 Saint Gobain Plaque de chauffage électrique
FR1280278A (fr) * 1961-02-08 1961-12-29 Thomson Houston Comp Francaise Perfectionnements aux éléments chauffants électriques
US3738256A (en) * 1972-05-19 1973-06-12 Lincoln Mfg Co Electric grill type cooking device
FR2202422B1 (fr) * 1972-08-01 1975-03-07 Saint Gobain
US3895216A (en) * 1974-09-30 1975-07-15 Gen Electric Low thermal mass solid plate surface heating unit
GB1498074A (en) * 1975-03-10 1978-01-18 Orbaiceta Electric resistance heating devices
DE7817410U1 (de) * 1977-10-14 1978-09-21 P. Ferrero & C. S.P.A., Alba, Cuneo (Italien) Vorrichtung zum anwaermen von fluessigen, in versiegelten behaeltern abgepackten nahrungsprodukten
CA1207366A (fr) * 1982-04-16 1986-07-08 Raychem Corporation Dispositifs electriques de forme allongee
KR890003052B1 (ko) * 1983-03-16 1989-08-19 칫소 엔지니어링 가부시끼 가이샤 띠형 전기발열장치
DE3545443A1 (de) * 1985-12-20 1987-06-25 Bosch Siemens Hausgeraete Kochstellenheizelement
DE3623130A1 (de) * 1986-07-09 1988-01-21 Ako Werke Gmbh & Co Strahlungsbeheizung
GB8717035D0 (en) * 1987-07-18 1987-08-26 Emi Plc Thorn Thick film track material

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0573618B1 (fr) * 1991-09-05 1995-02-08 Gabriel Bernaz Dispositif d'epilation electronique a haute frequence
WO1998036618A1 (fr) * 1997-02-17 1998-08-20 Strix Limited Resistances de chauffage electriques
GB2337684A (en) * 1997-02-17 1999-11-24 Strix Ltd Electric heaters
GB2337684B (en) * 1997-02-17 2001-02-28 Strix Ltd Electric heaters
GB2322273B (en) * 1997-02-17 2001-05-30 Strix Ltd Electric heaters
EP1161120A3 (fr) * 1997-02-17 2004-01-21 Strix Limited Dispositif de chauffage
US10251218B2 (en) 2015-04-27 2019-04-02 Haier Us Appliance Solutions, Inc. Appliance heating element
US10648390B2 (en) 2016-03-02 2020-05-12 Watlow Electric Manufacturing Company System and method for axial zoning of heating power
US10544722B2 (en) 2016-03-02 2020-01-28 Watlow Electric Manufacturing Company Virtual sensing system
US10724417B2 (en) 2016-03-02 2020-07-28 Watlow Electric Manufacturing Company Dual-purpose heater and fluid flow measurement system
US10760465B2 (en) 2016-03-02 2020-09-01 Watlow Electric Manufacturing Company Heater element having targeted decreasing temperature resistance characteristics
US10934921B2 (en) 2016-03-02 2021-03-02 Watlow Electric Manufacturing Company Heater element as sensor for temperature control in transient systems
US20170325293A1 (en) * 2016-05-06 2017-11-09 General Electric Company Appliance Heating Element with Integrated Temperature Sensing

Also Published As

Publication number Publication date
JPH02247996A (ja) 1990-10-03
EP0384640A3 (fr) 1992-03-18
GB8903829D0 (en) 1989-04-05
GB2228396A (en) 1990-08-22

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