EP0786923A2 - Système de commutation pour une protection contre le suréchauffement d'une plaque vitro-céramique d'une aire de cuisson - Google Patents

Système de commutation pour une protection contre le suréchauffement d'une plaque vitro-céramique d'une aire de cuisson Download PDF

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Publication number
EP0786923A2
EP0786923A2 EP96103542A EP96103542A EP0786923A2 EP 0786923 A2 EP0786923 A2 EP 0786923A2 EP 96103542 A EP96103542 A EP 96103542A EP 96103542 A EP96103542 A EP 96103542A EP 0786923 A2 EP0786923 A2 EP 0786923A2
Authority
EP
European Patent Office
Prior art keywords
glass ceramic
circuit system
control device
temperature
ceramic plate
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Withdrawn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
EP96103542A
Other languages
German (de)
English (en)
Other versions
EP0786923A3 (fr
Inventor
Jürgen Dipl.-Ing. Luther
Jürgen Dipl.-Ing. Leikam
Bernd Dipl.-Ing. Gehrke
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.)
AEG Hausgeraete GmbH
Original Assignee
AEG Hausgeraete GmbH
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 AEG Hausgeraete GmbH filed Critical AEG Hausgeraete GmbH
Publication of EP0786923A2 publication Critical patent/EP0786923A2/fr
Publication of EP0786923A3 publication Critical patent/EP0786923A3/fr
Withdrawn legal-status Critical Current

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    • 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
    • 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
    • H05B2213/04—Heating plates with overheat protection means
    • 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

  • the invention relates to a circuit system for protecting the glass ceramic plate of a hob to be heated by an electric heating element against excess temperatures.
  • the glass ceramic temperature In order to prevent damage and destruction of the glass ceramic plate due to impermissible excess temperatures, the glass ceramic temperature must be constantly monitored during cooking. According to the manufacturer, the critical glass ceramic temperature is around 580 ° C at the hottest point when the glass ceramic plate is idle on the top.
  • Known circuit systems use a so-called rod regulator as a mechanical temperature limiter for the glass ceramic plate. This rod regulator is arranged above the radiator, which is preferably designed as a heating coil, and expands when exposed to heat. The expansion behavior of the rod regulator influences a contact device for switching the electrical power supply for the radiator on and off.
  • a disadvantage of the known circuit system is the large spatial distance between the glass ceramic plate and the rod regulator.
  • the rod controller is always faked as a glass ceramic temperature that deviates significantly from the true temperature value.
  • the maximum permissible glass ceramic temperature must therefore be set relatively low, so that the efficiency of the hob remains low.
  • the circuit system must therefore be carefully adjusted before commissioning.
  • the rod controller also decelerates due to its close spatial arrangement to the heating coils, the heating process, since it is exposed to a high proportion of radiation, which leads to a rapid expansion of the rod and thus to early switching off of the power (see FIGS. 3 and 4).
  • the invention has for its object to improve the protection of the glass ceramic plate of a hob against excess temperatures.
  • the mechanical temperature limiter is replaced exclusively by electronic means. This means that the response times, i.e. the hysteresis of the circuit system as well as the heating-up times are greatly reduced. Due to the low hysteresis, no large temperature tolerances need to be taken into account when operating the circuit system.
  • the precise mode of operation of the circuit system according to the invention also enables a larger predetermined maximum permissible glass ceramic temperature. If the measured temperature on the glass ceramic plate corresponds to the predetermined temperature, the load circuit is switched off by the control device. According to the invention, this shutdown takes place with the same level of safety for the glass ceramic plate only at a higher measured temperature, so that the degree of utilization of the glass ceramic plate is advantageously increased.
  • the circuit system according to the invention can be easily integrated into control systems for controlling the heating power of the glass ceramic plate.
  • the control device can advantageously perform a double function by using the load circuit on the one hand to protect the temperature of the glass ceramic plate and on the other hand controls for the heating power control in an automatic cooking or cooking process.
  • an electronic sensor measures the glass ceramic temperature to a certain extent directly on the glass ceramic plate. This measurement enables a quick and accurate detection of the current glass ceramic temperature and therefore supports the great certainty in determining the really critical glass ceramic temperature at which the load circuit must be switched off.
  • the direct temperature measurement on the glass ceramic plate also contributes to the fact that the predetermined - maximum permissible glass ceramic temperature can be set higher.
  • control device controls an electronic switching element of the load circuit.
  • This electronic switching element supports short response times of the circuit system due to its fast switching capacity.
  • this circuit element works silently.
  • spark gaps and premature material wear are avoided, so that the operational safety of the entire hob is improved.
  • Claim 3 proposes a particularly simple control or regulation of the load circuit with the aid of a pulse packet control.
  • Claim 4 takes into account the safety regulations to be observed in the circuit system according to the invention.
  • a control circuit containing the control device and the load circuit are electrically isolated from one another.
  • claim 4 proposes an optoelectronic coupling of both circuits.
  • Claim 5 proposes a particularly space-saving and proven component in practice as an optoelectronic coupling.
  • Claim 6 relates to a safety measure in the event that the glass ceramic temperature continues to rise despite the measurement of the predetermined maximum permissible temperature.
  • the control device controls a switch connected in series in the load circuit and thereby interrupts the load circuit (protective shutdown).
  • the switch is preferably designed as a relay contact.
  • the protective shutdown can then be reversible or irreversible.
  • the relay is controlled dynamically by the control device, i.e. if the control is faulty, the relay drops out automatically, thereby interrupting the load circuit.
  • Claim 7 proposes, as an essential component of the control device, a microprocessor for the rapid and intelligent control of the load circuit.
  • the functional sequence of the microprocessor is monitored by a second microprocessor. This monitoring supports the operational safety of the circuit system even in the event of errors, e.g. in the event of a short circuit or an earth fault.
  • Claim 9 relates to a preferred arrangement of the electronic sensor for direct measurement of the glass ceramic temperature.
  • the senor is a temperature-dependent electrical resistance in the form of a conductor track arranged on the underside of the glass ceramic plate.
  • This conductor track designed as a gold track structure, has particularly favorable properties with regard to the electrical conductivity and the mechanical intrinsic stability and thereby supports an exact temperature measurement.
  • the conductor track sensor spans the glass ceramic plate approximately diametrically, an average temperature of the glass ceramic plate being determined by integrating the temperature profile along the conductor track.
  • the hottest temperature of the glass ceramic plate is preferably determined using a sensor having two electrodes, between which the electrical resistance of the glass ceramic plate is measured.
  • a conductor track sensor advantageously has a double function in that it also serves as an electrode of the sensor according to claim 13.
  • the circuit system shown in FIG. 1 and FIG. 2 serves to protect the glass ceramic plate of a hob to be heated by an electric heating element 1 against excess temperatures.
  • the radiator 1 is part of a one, two or three-phase load circuit 2.
  • the load circuit 2 is physically separated from a control circuit. This separation is indicated by a broken line 4 (Fig. 1, Fig. 2).
  • the control circuit contains a control device 3, to which two electronic sensors, a conductor track sensor 5 and a ceramic sensor 6 are connected. An average temperature is measured with the aid of the conductor track sensor 5 and the hottest temperature of the glass ceramic plate with the ceramic sensor 6 (FIG. 3, FIG. 4).
  • the sensors 5, 6 emit the sensor signals to the control device 3.
  • the sensor signals are processed in this control device 3 and compared with a predetermined, maximum permissible glass ceramic temperature T v . If the measured temperature value reaches or exceeds the maximum permissible glass ceramic temperature T v , the control device 3 controls the load circuit 2 of the heating element 1 electronically and reduces or interrupts the electrical power supplied to the heating element 1 until the measured temperature value falls below the predetermined glass ceramic temperature T v again.
  • an electronic switching element 7 is connected in series in the load circuit 2. This switching element 7 closes, reduces and interrupts in load circuit 2 depending on a control signal from the control device.
  • the switching element 7 is a pulse packet controller designed with a triac.
  • the control input 8 of the triac is driven by a signal output 9 of the control device which supplies the control signal.
  • the control device and the switching element 7 are optoelectronically coupled by a phototransistor 10 and thereby galvanically separated from one another at the dividing line 4.
  • the operating voltage of the radiator 1 is also galvanically isolated from the operating voltage of the control device 3 by an isolating transformer 11.
  • the AC voltage on the secondary side of the isolating transformer 11 is converted to an operating voltage suitable for the control device 3.
  • the circuit included in the control circuit is to be implemented in protective extra-low voltage and with an 8 mm isolating path.
  • a relay K1 is also connected in series. In the event of a fault, this relay K1 is controlled by the control device and thereby interrupts the entire load circuit 2 (protective shutdown). The fault occurs when the predetermined glass ceramic temperature T v is exceeded despite the control of the switching element 7. This load circuit interruption can be reversible or irreversible. For safety, relay K1 is controlled dynamically, ie relay K1 drops out automatically if the control is faulty.
  • the load circuit 2 can be switched off by an operator by means of a main switch 12 (3 mm isolating distance).
  • a main switch 12 (3 mm isolating distance).
  • the control circuit remains constantly live.
  • the main switch 12 can be bridged by a second relay K2 in the control circuit until, for example, certain safety functions (residual heat indicator) have been processed and the entire system then automatically switches to the de-energized state (to save energy).
  • the control circuit When the main switch is actuated, the control circuit is energized, the control unit 3 controls the relay K2 and the main switch is bridged via the relay contact K2. If the main switch 12 is switched off (load circuit de-energized), the control circuit is supplied with current until, for example, the residual heat is undershot and the relay K2 drops out via the control unit 3 and the entire system is automatically de-energized.
  • the control device 3 contains, as an essential component, a microprocessor ⁇ P1 for processing the sensor signal and for controlling the load circuit 2.
  • a microprocessor ⁇ P1 for processing the sensor signal and for controlling the load circuit 2.
  • a short circuit or an earth fault must not override the function of the circuit system.
  • the control device contains a second microprocessor ⁇ P2, which monitors the microprocessor ⁇ P1 for functionality and plausibility.
  • the electronic sensors 5, 6 are arranged directly on the underside of the glass ceramic plate.
  • the conductor path sensor 5 is a conductor path-shaped and temperature-dependent electrical resistance, the conductor path of which spans the glass ceramic plate approximately diametrically.
  • the conductor track sensor is mainly used for control tasks to regulate the heating output below the predetermined maximum permissible glass ceramic temperature T v (however, this is not absolutely necessary for overtemperature protection).
  • the ceran sensor 6 is used to monitor whether the measured glass ceramic temperature reaches or exceeds the predetermined temperature T v . It detects the hottest temperature of the glass ceramic plate by measuring the electrical resistance of the glass ceramic plate between two electrodes.
  • the ceramic sensor 6 measures the hottest temperature and the conductor track sensor 5 measures the average temperature of the glass ceramic plate. As long as the temperature value measured by the Ceran sensor 6 remains below the predetermined temperature T v , the control device does not interrupt the load circuit 2. The heating power for the saucepan or the like placed on the glass ceramic plate therefore rises continuously.
  • the control device controls the load circuit 2 and interrupts the power supply for the heating element 1 via the relay contact K1, so that no heating power is delivered to the saucepan.
  • the control device drives the load circuit 2 again in order to close it. Heating output is again given to the saucepan. This protective shutdown is superimposed on the actual temperature control (double safety).
  • a permanent protective shutdown is also conceivable. While in a normal control process theoretically no protective shutdown can occur because an overtemperature is avoided, a protective shutdown that occurs nevertheless indicates a significant malfunction, the remedy of which should be left to customer service.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Control Of Resistance Heating (AREA)
  • Protection Of Static Devices (AREA)
  • Control Of Temperature (AREA)
EP96103542A 1996-01-26 1996-03-07 Système de commutation pour une protection contre le suréchauffement d'une plaque vitro-céramique d'une aire de cuisson Withdrawn EP0786923A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19602649 1996-01-26
DE19602649 1996-01-26

Publications (2)

Publication Number Publication Date
EP0786923A2 true EP0786923A2 (fr) 1997-07-30
EP0786923A3 EP0786923A3 (fr) 1998-01-07

Family

ID=7783670

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96103542A Withdrawn EP0786923A3 (fr) 1996-01-26 1996-03-07 Système de commutation pour une protection contre le suréchauffement d'une plaque vitro-céramique d'une aire de cuisson

Country Status (1)

Country Link
EP (1) EP0786923A3 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0967840A2 (fr) 1998-06-24 1999-12-29 Cherry GmbH Dispositif de limitation de température dans le cas d'une plaque vitrocéramique
EP1028602A2 (fr) * 1999-02-13 2000-08-16 Schott Glas Procédé de reconnaissance d'une cuisson à vide d'un élément de vaisselle placé sur des plaques possédant une surface de cuisson vitro-céramique ainsi que le dispositif correspondant
ES2151805A1 (es) * 1998-03-16 2001-01-01 Santis Danilo De Sistema de control electronico de potencia para placas vitroceramicas de cocina con sensor optico de presencia de olla.
DE102005056708A1 (de) * 2005-11-28 2007-05-31 BSH Bosch und Siemens Hausgeräte GmbH Schaltungsanordnung und Verfahren zum Verhindern einer Überhitzung eines Kochgeräts
WO2008017397A1 (fr) * 2006-08-08 2008-02-14 E.G.O. Elektro-Gerätebau GmbH Dispositif de commutation pour un dispositif de chauffage ainsi que dispositif de chauffage
WO2008064446A1 (fr) * 2006-12-01 2008-06-05 Whirlpool S.A Dispositif et procédé permettant de commander un élément chauffant d'une table de cuisson vitrocéramique

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2060329A (en) * 1979-10-11 1981-04-29 Thorn Domestic Appliances Ltd Cooking hobs
GB2138659A (en) * 1980-01-14 1984-10-24 Johnson Matthey Plc Glass Ceramic Hob including Temperature Sensor
EP0138314A1 (fr) * 1983-08-31 1985-04-24 THORN EMI Appliances Limited Appareil de chauffage
US4740664A (en) * 1987-01-05 1988-04-26 General Electric Company Temperature limiting arrangement for a glass-ceramic cooktop appliance
DE3736005A1 (de) * 1987-10-23 1989-05-03 Bosch Siemens Hausgeraete Steuereinheit fuer elektronische kochstellen-temperaturregelung mit temperatursensor
EP0471171A2 (fr) * 1990-07-18 1992-02-19 Schott Glaswerke Dispositif pour la régulation et le limitation de la puissance d'une surface de chauffage en céramique ou un matériau similaire
EP0481162A2 (fr) * 1990-10-15 1992-04-22 Lancet S.A. Appareil de cuisson domestique

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2060329A (en) * 1979-10-11 1981-04-29 Thorn Domestic Appliances Ltd Cooking hobs
GB2138659A (en) * 1980-01-14 1984-10-24 Johnson Matthey Plc Glass Ceramic Hob including Temperature Sensor
EP0138314A1 (fr) * 1983-08-31 1985-04-24 THORN EMI Appliances Limited Appareil de chauffage
US4740664A (en) * 1987-01-05 1988-04-26 General Electric Company Temperature limiting arrangement for a glass-ceramic cooktop appliance
DE3736005A1 (de) * 1987-10-23 1989-05-03 Bosch Siemens Hausgeraete Steuereinheit fuer elektronische kochstellen-temperaturregelung mit temperatursensor
EP0471171A2 (fr) * 1990-07-18 1992-02-19 Schott Glaswerke Dispositif pour la régulation et le limitation de la puissance d'une surface de chauffage en céramique ou un matériau similaire
EP0481162A2 (fr) * 1990-10-15 1992-04-22 Lancet S.A. Appareil de cuisson domestique

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2151805A1 (es) * 1998-03-16 2001-01-01 Santis Danilo De Sistema de control electronico de potencia para placas vitroceramicas de cocina con sensor optico de presencia de olla.
EP0967840A2 (fr) 1998-06-24 1999-12-29 Cherry GmbH Dispositif de limitation de température dans le cas d'une plaque vitrocéramique
DE19828052A1 (de) * 1998-06-24 1999-12-30 Cherry Gmbh Einrichtung zur Temperaturbegrenzung eines Glaskeramikkochfelds
EP0967840A3 (fr) * 1998-06-24 2001-11-14 Cherry GmbH Dispositif de limitation de température dans le cas d'une plaque vitrocéramique
EP1028602A2 (fr) * 1999-02-13 2000-08-16 Schott Glas Procédé de reconnaissance d'une cuisson à vide d'un élément de vaisselle placé sur des plaques possédant une surface de cuisson vitro-céramique ainsi que le dispositif correspondant
EP1028602A3 (fr) * 1999-02-13 2002-01-02 Schott Glas Procédé de reconnaissance d'une cuisson à vide d'un élément de vaisselle placé sur des plaques possédant une surface de cuisson vitro-céramique ainsi que le dispositif correspondant
DE102005056708A1 (de) * 2005-11-28 2007-05-31 BSH Bosch und Siemens Hausgeräte GmbH Schaltungsanordnung und Verfahren zum Verhindern einer Überhitzung eines Kochgeräts
US7345259B2 (en) 2005-11-28 2008-03-18 Bsh Bosch Und Siemens Hausgeraete Gmbh Circuit arrangement and method for preventing overheating of a cooking appliance
WO2008017397A1 (fr) * 2006-08-08 2008-02-14 E.G.O. Elektro-Gerätebau GmbH Dispositif de commutation pour un dispositif de chauffage ainsi que dispositif de chauffage
WO2008064446A1 (fr) * 2006-12-01 2008-06-05 Whirlpool S.A Dispositif et procédé permettant de commander un élément chauffant d'une table de cuisson vitrocéramique

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Publication number Publication date
EP0786923A3 (fr) 1998-01-07

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