WO1995016334A1 - Dispositif permettant de determiner la charge thermique d'une zone de cuisson - Google Patents

Dispositif permettant de determiner la charge thermique d'une zone de cuisson Download PDF

Info

Publication number
WO1995016334A1
WO1995016334A1 PCT/DK1994/000457 DK9400457W WO9516334A1 WO 1995016334 A1 WO1995016334 A1 WO 1995016334A1 DK 9400457 W DK9400457 W DK 9400457W WO 9516334 A1 WO9516334 A1 WO 9516334A1
Authority
WO
WIPO (PCT)
Prior art keywords
rod
temperature
cooking zone
sensing elements
temperature sensing
Prior art date
Application number
PCT/DK1994/000457
Other languages
English (en)
Inventor
Johan Axelson
Palle Christoffersen
Daniel Schneider
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
Application filed by Aktiebolaget Electrolux filed Critical Aktiebolaget Electrolux
Priority to EP95901364A priority Critical patent/EP0740895A1/fr
Priority to AU10642/95A priority patent/AU1064295A/en
Publication of WO1995016334A1 publication Critical patent/WO1995016334A1/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
    • H05B3/68—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
    • H05B3/746—Protection, e.g. overheat cutoff, hot plate indicator
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/22—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element being a thermocouple

Definitions

  • a device for determining the thermal load of a cooking zone A device for determining the thermal load of a cooking zone.
  • the invention relates to an apparatus for establishing the thermal load on a cooking zone heated by radiation and/or convection from a heating element or elements placed at some distance from the lower surface of the cooking zone and comprising temperature sensing elements and evaluation circuit- It has been determined that modern cooking zones which are areas of in particular glass or ceramic top plates require far more sophistication in their control than mere wattage adjustment. It is desirable to be able to control the temperature, possibly within specific ranges, to determine whether a load is applied to a cooking zone and to determine fault conditions which should cause the power supply to shut down.
  • the heating element or elements are regarded as sources of heat
  • the intervening airspace is regarded as an impedance to radiant heat transfer as well as a conductance with respect to e.g. convective heat transfer.
  • the load on a cooking zone is regarded as a drain, and by measuring the temperature at more than one location it is possible to determine the flow of energy into the load. The result of the evaluation will be used to control the supply of energy to the cooking zone by methods some of which are standard in the field, in their simpelst form as a thermostat.
  • a preferred embodiment specified in claim 3 uses thermal shielding interspersed between the actual sensors and the heating elements.
  • a further embodiment according to claim 4 maximises the influence from the thermal load in that the temperature sensing elements are in close proximity to the cooking zone.
  • a further embodiment simplifies calibration and the evaluation circuit according to claim 5 by the temperature sensing elements being disposed in a plane essentially parallel to the cooking zone.
  • a further advantageous embodiment according to claim 6 further simplifies evaluation by letting each temperature sensing element provide an average of the temperatures prevalent in the neighbourhood of each temperature sensing element. This average may be
  • SUBSTITUTESHEET obtained by letting the temperature sensing elements have an appreciable physical extent or by letting them be in close thermal contact with surfaces or bodies covering an area interspersed between the heat source arid the heat drain.
  • the temperature sensing elements comprise a rod with a diameter sufficient to attain a temperature which is related to the average of the temperatures it is subjected to along its lenght according to a further embodiment of the invention specified in claim 7.
  • thermoelectric voltages of conductors or semiconductors e.g. as used in thermocouples
  • each end of the rod is a part of a thermoelectric junction, the other parts being constituted by the leads connecting the ends of said rod to the evaluation circuit.
  • a further advantageous simplification is obtained according to claim 10 when the characteristic thermoelectric voltage of the rod falls within the range + 10% of the mean value of the characteristic thermal voltages of the lead materials.
  • the errors obtained are compensatable, but in the case where the characteristic thermoelectric voltage is exactly midway between the characteristic thermal voltages of the lead materials there is no need for compensation.
  • SUBSTITUTESHEET A preferred embodiment provides a simple and efficient way of obtaining two sensing elements as above described from one and the same rod by according to claim 11 letting the rod be connected at its midpoint to a further lead which establishes a connection to the evaluation circuit.
  • An efficient integral construction according to claim 12 which is self-compensating is obtained by combining the thermal shield with the sensors in that the rod is made of an electrically conductive material with essentially the same thermal expansion coefficient as the shield.
  • a further advantageous embodiment obtains an additional signal representative of other areas below the cooking zone surface by combining the features of claim 11 and 12 in claim 13 in that the further lead is not directly connected to the midpoint but to a thermally shielded further rod going from the midpoint into another area in the plane of the sensing elements.
  • the model of the energy transport expressed as a distributed source of energy, a cross section in which energy flows and a drain is useful, because the flow will be determined by the area or part of the cross section which has a lower temperature and which will hence absorb relatively more heat.
  • a point measurement of temperature is meaningless, because the temperature at a single point is determined only by a fraction of the total load.
  • the present invention is based on the realization that although the average temperature is useful for a simple thermostat function, the utilization of several temperature measurement contributions enables a much more precise control of energy supply in response to the acutal load conditions.
  • SUBSTITUTESHEET Fig. 1 shows the principle underlying the present invention
  • Fig. 2 shows a preferred placement of the elements of the invention
  • FIG. 3 shows a further preferred and more detained representation of the elements shown in Fig. 2,
  • Fig. 4a shows in perspective the structure of a preferred sensor element for an apparatus according to the invention
  • Fig. 4b shows a side view of a preferred sensor according to the invention
  • Fig. 5 shows an embodiment similar to that of Fig. 3 but utilizing a sensor element according to Fig. 4,
  • Fig. 6 shows the same seen from above
  • Fig. 7 shows the principle of a detector reaching over a larger area
  • Fig. 8 shows a sensor element covering a larger area based on the principle shown in Fig. 4 and 6.
  • Fig. 1 shows a schematic section through a cooking zone according to invention.
  • a cooking zone 1 which may be part of the ceramic top plate has the edge 3 of a heating chamber 5 resting against it.
  • the material of the heating chamber is usually a soft ceramic fibrous material.
  • the chamber 5 defines a heat transfer volume V in which a series of heating elements 7 transfer heat indicated by a dotted Q to the hot zone 1.
  • a temperature sensor 8 with at least one sensing element is provided in close approximation to the cooking zone.
  • the sensor delivers an electrical signal e(th) in dependence of the temperature th.
  • the temperature sensor is mounted such that thermic drain resistances, such as Rth are as large as possible. Thereby the influence on the temperature measurement of spurious heat transfer shown as dotted QST are minimized.
  • the temperature sensor may be an NTC or a PTC resistor or a thermocouple or thermojunction.
  • thermic resistor represented by a support for the temperature sensor will be as large as possible when the lenght of the support is maximum and subjected to as constant a temperature as possible which in practice means a disposition in parallel to the cooking zone and extending to the periphery.
  • thermocouples 9a and 9b are used in the volume between the heating elements and the cooking zone.
  • a preferred embodiment shown in Fig. 4a and Fig. 4b uses two series coupled thermojunctions obtained between the lead 13 and the rod 14, and the rod 14 and the lead 15.
  • the rod performs an averaging of temperatures it is subjected to, and the leads 13 and 15 have a diameter which is so small that they contribute very little to the temperature distribution in the rod 14.
  • the leads 13 and 15 are of different materials and are insulated with a heat resistant insulation.
  • the junction between the rod and the wires is by spot welding in order not to introduce extraneous materials.
  • the lead 15 is connected to the far end of the rod 14 and is taken below the whole lenght of the rod inside a thermal shield 16. In the practical embodiment the wires are clamped in the shield and serve to support the rod in the position shown.
  • the shield 16 is provided with prongs 18 for easy engagement with the soft edge material of the insulation at 3 (Fig. 1) .
  • the material of the rod and wires are preferably suitable alloys of Cr and Ni, the exact proportion of which is simple to determine by the person skilled in the art according to known relationships with the characteristic thermal voltages. However other combinations of material may be found which are equally useful. It is advantageous to make the thermal shield in the same material as the rod or at least with the same
  • TITUTESHEET linear thermal expansion coefficient as this will stress minimally the spot welds used to connect the leads 13, 15 and which support the rod at each end.
  • Fig. 5 is shown how the temperature sensor is disposed in conjunction with the cooking zone, and on Fig. 6 the arrangement is seen from above.
  • thermocouples are created at their junctions 20, 21, and 22.
  • the outputs 24a and 24b provide the sum of the thermovoltages of the elements 20 and 21, while at the thermocouple 22 a single thermovoltage is available at the two outputs 24c. Another sum is available beetween the outputs 24c and 24a.
  • Fig. 8 a construction very similar to that of Fig. 4 is shown, however in the view of Fig. 6. It is an extension of the concept of the sums of thermovoltages which uses a star connection rather than a delta connection as described in conjunction with Fig. 7.
  • a further rod 14 is spot welded to the midpoint of the previously described rod 14, and a further insulated lead 13 is available for a signal for evaluation.
  • the concept of the measurement used in the apparatus according to the invention is not limited to thermocouples, as the main concept on which it is based is that of the need to provide temperatures for the sensors which depend on larger parts of the area of the cooking plate in order to determine with precision the thermal load conditions on the upper surface of the cooking plate.

Abstract

La surface en vitrocéramique des zones de cuisson modernes doit être très surveillée à cause du risque de surchauffe et de la présence éventuelle de chaleur résiduelle qui constitue un risque invisible pour l'utilisateur. Il est également souhaitable de moduler l'apport de chaleur selon les nécessités concernant les récipients et aliments à faire chauffer. Selon l'invention, on utilise un capteur thermo-électrique à une ou deux dimensions détectant le rayonnement produit par la surface en vitrocéramique, en étant éventuellement protégé du rayonnement direct émis par les éléments chauffants.
PCT/DK1994/000457 1993-12-06 1994-12-06 Dispositif permettant de determiner la charge thermique d'une zone de cuisson WO1995016334A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP95901364A EP0740895A1 (fr) 1993-12-06 1994-12-06 Dispositif permettant de determiner la charge thermique d'une zone de cuisson
AU10642/95A AU1064295A (en) 1993-12-06 1994-12-06 A device for determining the thermal load of a cooking zone

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CH3632/93-3 1993-12-06
CH363293 1993-12-06
DK0579/94 1994-05-20
DK57994 1994-05-20

Publications (1)

Publication Number Publication Date
WO1995016334A1 true WO1995016334A1 (fr) 1995-06-15

Family

ID=25693479

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1994/000457 WO1995016334A1 (fr) 1993-12-06 1994-12-06 Dispositif permettant de determiner la charge thermique d'une zone de cuisson

Country Status (3)

Country Link
EP (1) EP0740895A1 (fr)
AU (1) AU1064295A (fr)
WO (1) WO1995016334A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997019298A1 (fr) * 1995-11-21 1997-05-29 Aktiebolaget Electrolux Surface de cuisson et son systeme de commande
DE10120136A1 (de) * 2001-04-25 2002-11-14 Frima Sa Garverfahren und Gargerät mit automatischer Garguterkennung
WO2003007660A1 (fr) * 2001-07-11 2003-01-23 Ceramaspeed Limited Dispositif electrique chauffant par rayonnement incorporant un ensemble detecteur de temperature
WO2006045705A1 (fr) * 2004-10-29 2006-05-04 BSH Bosch und Siemens Hausgeräte GmbH Plaque de cuisson dotee d'un capteur de temperature
EP1672341A1 (fr) * 2004-12-18 2006-06-21 Miele & Cie. KG Méthode pour déterminer le coefficient d'émissivité d'une surface destinée à être chauffée.

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3710076A (en) * 1972-02-17 1973-01-09 J Frazier Radiant surface-heater and temperature sensing assembly
US4414465A (en) * 1980-03-05 1983-11-08 Thorn Domestic Appliances (Electrical) Ltd. Cooking apparatus
EP0138314A1 (fr) * 1983-08-31 1985-04-24 THORN EMI Appliances Limited Appareil de chauffage
DE3736005A1 (de) * 1987-10-23 1989-05-03 Bosch Siemens Hausgeraete Steuereinheit fuer elektronische kochstellen-temperaturregelung mit temperatursensor
US5227610A (en) * 1990-07-18 1993-07-13 Schott Glaswerke Process and device for indicating an anomalous thermal stress condition in a heating surface made from glass ceramic or a comparable material
US5256860A (en) * 1993-01-22 1993-10-26 Therm-O-Disc, Incorporated Control for glass cooktops utilizing rod-shaped thermistor
US5258736A (en) * 1990-07-18 1993-11-02 Schott Glaswerke Temperature sensor or temperature sensor arrangement made from glass ceramic and bonding film resistors

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3710076A (en) * 1972-02-17 1973-01-09 J Frazier Radiant surface-heater and temperature sensing assembly
US4414465A (en) * 1980-03-05 1983-11-08 Thorn Domestic Appliances (Electrical) Ltd. Cooking apparatus
EP0138314A1 (fr) * 1983-08-31 1985-04-24 THORN EMI Appliances Limited Appareil de chauffage
DE3736005A1 (de) * 1987-10-23 1989-05-03 Bosch Siemens Hausgeraete Steuereinheit fuer elektronische kochstellen-temperaturregelung mit temperatursensor
US5227610A (en) * 1990-07-18 1993-07-13 Schott Glaswerke Process and device for indicating an anomalous thermal stress condition in a heating surface made from glass ceramic or a comparable material
US5258736A (en) * 1990-07-18 1993-11-02 Schott Glaswerke Temperature sensor or temperature sensor arrangement made from glass ceramic and bonding film resistors
US5256860A (en) * 1993-01-22 1993-10-26 Therm-O-Disc, Incorporated Control for glass cooktops utilizing rod-shaped thermistor

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997019298A1 (fr) * 1995-11-21 1997-05-29 Aktiebolaget Electrolux Surface de cuisson et son systeme de commande
DE10120136A1 (de) * 2001-04-25 2002-11-14 Frima Sa Garverfahren und Gargerät mit automatischer Garguterkennung
WO2003007660A1 (fr) * 2001-07-11 2003-01-23 Ceramaspeed Limited Dispositif electrique chauffant par rayonnement incorporant un ensemble detecteur de temperature
US6940048B2 (en) 2001-07-11 2005-09-06 Ceramaspeed Limited Radiant electric heater incorporating a temperature sensor assembly
CN100334922C (zh) * 2001-07-11 2007-08-29 塞拉麦斯皮德有限公司 包括辐射电加热器和温度传感器组件的烹调设备
WO2006045705A1 (fr) * 2004-10-29 2006-05-04 BSH Bosch und Siemens Hausgeräte GmbH Plaque de cuisson dotee d'un capteur de temperature
EP1672341A1 (fr) * 2004-12-18 2006-06-21 Miele & Cie. KG Méthode pour déterminer le coefficient d'émissivité d'une surface destinée à être chauffée.
US7316505B2 (en) 2004-12-18 2008-01-08 Miele & Cie Kg Method of defining the emission coefficient of a surface to be heated

Also Published As

Publication number Publication date
AU1064295A (en) 1995-06-27
EP0740895A1 (fr) 1996-11-06

Similar Documents

Publication Publication Date Title
US5258736A (en) Temperature sensor or temperature sensor arrangement made from glass ceramic and bonding film resistors
US6626835B1 (en) Infrared sensor stabilizable in temperature, and infrared thermometer with a sensor of this type
US5352864A (en) Process and device for output control and limitation in a heating surface made from glass ceramic or a comparable material
US5227610A (en) Process and device for indicating an anomalous thermal stress condition in a heating surface made from glass ceramic or a comparable material
CA1207345A (fr) Appareil de pesage incorpore a une table de cuisson
US4237368A (en) Temperature sensor for glass-ceramic cooktop
US5176451A (en) Temperature sensor
EP0541697B2 (fr) Detecteur de rayonnement avec systeme de reference thermique place a distance
US3939706A (en) High energy sensor
US5041809A (en) Glass-ceramic temperature sensor for heating ovens
CN102160456A (zh) 加热元件和用于操作这种加热元件的方法
US6815648B2 (en) Contact sensor arrangements for glass-ceramic cooktop appliances
US20020136263A1 (en) Temperature sensing probe assembly
CA1198139A (fr) Methode et dispositif pour limiter l'evaporation d'un liquide dans un ustensile depose sur l'element chauffant d'une cuisiniere
US5589094A (en) Microwave oven employing thermopile type sensor
US4063095A (en) Balancing radiometer
EP0740895A1 (fr) Dispositif permettant de determiner la charge thermique d'une zone de cuisson
US6538238B1 (en) Long term calibration of sensor assembly for glass-ceramic cooktop appliance
JP2001230062A (ja) 誘導加熱調理器
AU2012265567B2 (en) Temperature sensing for an electric heating device
JP2007506067A (ja) 沸騰レベルを制御する方法
JPS62231148A (ja) 熱分析装置
US7316505B2 (en) Method of defining the emission coefficient of a surface to be heated
CA1129923A (fr) Sonde thermometrique pour plan de cuisson verre/ceramique
JPH05223763A (ja) 熱電対を用いた熱分析装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AM AT AT AU BB BG BR BY CA CH CN CZ CZ DE DE DK DK ES FI FI GB GE HU JP KE KG KP KR KZ LK LT LU LV MD MG MN MW NL NO NZ PL PT RO RU SD SE SI SK SK TJ TT UA US UZ VN

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): KE MW SD SZ AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN ML MR NE SN TD TG

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 1995901364

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWP Wipo information: published in national office

Ref document number: 1995901364

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 1995901364

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: CA