EP0208823A1 - Résistance de chauffage électrique - Google Patents

Résistance de chauffage électrique Download PDF

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Publication number
EP0208823A1
EP0208823A1 EP85850239A EP85850239A EP0208823A1 EP 0208823 A1 EP0208823 A1 EP 0208823A1 EP 85850239 A EP85850239 A EP 85850239A EP 85850239 A EP85850239 A EP 85850239A EP 0208823 A1 EP0208823 A1 EP 0208823A1
Authority
EP
European Patent Office
Prior art keywords
temperature
resistance
parts
electrical resistance
metallic
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Withdrawn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
EP85850239A
Other languages
German (de)
English (en)
Inventor
Bengt Magnusson
Thor Hegbom
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.)
Kanthal AB
Original Assignee
Kanthal AB
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 Kanthal AB filed Critical Kanthal AB
Priority to EP85850239A priority Critical patent/EP0208823A1/fr
Publication of EP0208823A1 publication Critical patent/EP0208823A1/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Withdrawn legal-status Critical Current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
    • H05B3/10—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heater 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
    • H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
    • H05B3/748—Resistive heating elements, i.e. heating elements exposed to the air, e.g. coil wire heater

Definitions

  • This invention is for an electrical resistance heating element.
  • the invention also is for a cooker hot-plate or the like where one or more elements according to the invention are being used.
  • Electrical stoves for household use comprise different kinds of hot-plates. Most important are massive plates, tubular plates and glass hot-plates. In all of these heating is by means of metallic resistance elements which on the first two cases are enclosed in a plate or tube and surrounded by insulating material while in the case of glass hot-plates the element is positioned on an insulating material and radiates heat towards the glass plate which is above the element at a suitable distance.
  • the purpose of the present invention is to obtain, in addition to the heating, a light signal which indicates a hot surface. Another object of the invention is to obtain this light signal in connection with the heating without any delay. A further objective of the invention is to obtain faster heating compared to previously used elements. Also a further objective of the invention is to obtain such a heat distribution from the heating element that an equal heating all over the surface of a pan or the like is achieved.
  • An electrical resistance heating element is characterized in that it comprises at least two parts made from different materials. These materials shall be such that at least one part of the element is made from a material having a small temperature factor and at least one part is made from a material having a greater, positive temperature factor.
  • the parts are electrically connected to each other and preferr- tably at least two parts from different materials are connected in series to each other.
  • Temperature factor (c T ) means the ratio of a the electrical resistance of a material at one temperature and the resistance of the same material at another,lower temperature. Depending on whether the resistance of the material increases or decreases as the temperature is increased the temperature factor can be positive or negative.
  • Examples of materials having a small positive temperature factor are alloys of nickel-chromium or iron-chromium-aluminium, the temperature factor mostly being not greater than 1.2 in the temperature interval 0-1200°C.
  • the temperature factor for this kind of materials is generally positive and the numerical value of any possible negative factor is small.
  • Materials having a great temperature factor are e. g. molybdenum, tungsten and molydenumdisilicide. At an increase of the temperature from ambient to 1200°C the temperature factor for molybdenumdisilicide resistance elements is about 10. Variations may occur depending upon the exact composition of the material, possible additives, porosities etc. Corresponding values for molybdenum and tungsten are 5-7.
  • a resistance element according to the invention comprises, as mentioned above, at least two parts which are electrically connected to each other.
  • the connection can be direct without any intermediate connection means but for many applications materials are used which have such pro perties that a immediate connection of the materials is improper.
  • a resistance element according to the invention thus comprises a plurality of parts that are connected to each other and jointly operate to heat a certain surface or object.
  • a resistance element according to the invention is shown in figure 1 and figure 2 shows how the parts of the element are connected to each other and an outside voltage source.
  • the resistance element has two parts, one part made from metal-ceramic material (1), another part made from metallic material (2). Both parts of the element have connection ends (4a,4b,5a,5b). The parts of the element are resting on a board of insulating material.
  • the two materials of the resistance element so that the material (1) which forms the outer shape of the element has a temperature factor such that 5 ⁇ c T ⁇ 15 while the inner part of the element (2) is made from a material such that -1.25 ⁇ c T ⁇ 1.25 in the temperature interval 0-1200°C.
  • the elements are pref- ferably of such dimensions that at ambient temperature the ratio of the resistance of the two materials is 1:25 ⁇ R,:R, ⁇ 1:5 where R, is the resistance of the material having the greater c T and R2 is the resistance of the material having the smaller cT. .
  • the ratio at the operating temperature is preferrably 1:5 ⁇ R,:R : ⁇ 1:1.
  • the maximum working temperature of the parts of the resistance element will only in exceptional cases be more than 1000°C even though the materials of the element can be used at higher temperatures.
  • materials and dimensions of the parts of the element as said above one will achieve the advantages wanted such as rapid heating up,rapid control respons, a "light signal" corresponding to the temperature and a controlled heat distribution over the heated surface.
  • connection parts made from the same materials as the parts of the element but the cross sectional area is larger.
  • the two parts of the element are connected to each other by a connector (7) made from a material having a low electrical resistance.
  • the leads to the parts of the element are so designed that they will have a low temperature at the point of connection.
  • the connector may thus be made from e. g. aluminium or copper and connection may be by means of soldering or a mechanical clamp. It is also possible to design a connector so that its heat conducting capacity is relatively high and it can then be directly connected to the element without the use of a special connector.
  • the parts of the element may also be connected via a special connection box. This can be especially suitable is one wants to change the way the parts of the eioment are connected to each other for control purposes.
  • a resistance element is made from two parts as shown in figure 1.
  • the outer part is made from a molybdenumdisilicide based material, availab le under the name KANTHAL SUPER, in the form of a wire having a diameter of .5 mm and a total length of 750 mm.
  • the inner part of the element was made from a iron-chromium-aluminum-alloy available under the name KANTHAL. It was in the form of a wire having a diameter of .75 mm and coiled to a spiral with a diameter of 5 mm. The total length was 6 m. At ambient temperature the resistance of the outer part was 1 ohm, of the inner part 18 ohms.
  • the element was connected to a 220 volts source.
  • the outer part of the element was thereby heated and illuminated within 2 seconds. Due to the low resistance of this material at ambient temperature the current was high immediately after switching on. The current then decreases rapidly as the resistance increases as a result of the increasing temperature.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Resistance Heating (AREA)
EP85850239A 1985-07-15 1985-07-15 Résistance de chauffage électrique Withdrawn EP0208823A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP85850239A EP0208823A1 (fr) 1985-07-15 1985-07-15 Résistance de chauffage électrique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP85850239A EP0208823A1 (fr) 1985-07-15 1985-07-15 Résistance de chauffage électrique

Publications (1)

Publication Number Publication Date
EP0208823A1 true EP0208823A1 (fr) 1987-01-21

Family

ID=8194719

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85850239A Withdrawn EP0208823A1 (fr) 1985-07-15 1985-07-15 Résistance de chauffage électrique

Country Status (1)

Country Link
EP (1) EP0208823A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0300685A2 (fr) * 1987-07-18 1989-01-25 THORN EMI plc Amélioration pour et relative aux matériaux pour circuit à couche épaisse
EP0303854A1 (fr) * 1987-08-18 1989-02-22 E.G.O. Elektro-Geräte Blanc u. Fischer Radiateur électrique
EP0335617A2 (fr) * 1988-03-25 1989-10-04 THORN EMI plc Limitateur de courant pour éléments chauffants à couche épaisse

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB825049A (en) * 1955-11-02 1959-12-09 Cyril Lacy Hulbert Improvements in or relating to electric heating elements
GB1273023A (en) * 1969-02-18 1972-05-03 Electricity Council Improvements in or relating to electric cookers
DE2210651A1 (de) * 1972-03-06 1973-09-20 Licentia Gmbh Elektrisch beheizte kochplatte aus glaskeramik
US3912905A (en) * 1974-02-25 1975-10-14 Kanthal Corp Electric resistance heating device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB825049A (en) * 1955-11-02 1959-12-09 Cyril Lacy Hulbert Improvements in or relating to electric heating elements
GB1273023A (en) * 1969-02-18 1972-05-03 Electricity Council Improvements in or relating to electric cookers
DE2210651A1 (de) * 1972-03-06 1973-09-20 Licentia Gmbh Elektrisch beheizte kochplatte aus glaskeramik
US3912905A (en) * 1974-02-25 1975-10-14 Kanthal Corp Electric resistance heating device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0300685A2 (fr) * 1987-07-18 1989-01-25 THORN EMI plc Amélioration pour et relative aux matériaux pour circuit à couche épaisse
EP0300685A3 (fr) * 1987-07-18 1991-03-20 THORN EMI plc Amélioration pour et relative aux matériaux pour circuit à couche épaisse
EP0303854A1 (fr) * 1987-08-18 1989-02-22 E.G.O. Elektro-Geräte Blanc u. Fischer Radiateur électrique
US4931621A (en) * 1987-08-18 1990-06-05 E.G.O. Elektro-Gerate Blanc U. Fischer Electric heater
EP0335617A2 (fr) * 1988-03-25 1989-10-04 THORN EMI plc Limitateur de courant pour éléments chauffants à couche épaisse
EP0335617A3 (fr) * 1988-03-25 1991-03-20 THORN EMI plc Limitateur de courant pour éléments chauffants à couche épaisse

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18D Application deemed to be withdrawn

Effective date: 19871218

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Inventor name: HEGBOM, THOR

Inventor name: MAGNUSSON, BENGT