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WO1999011979A1 - Dispositif a arret de securite - Google Patents

Dispositif a arret de securite Download PDF

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Publication number
WO1999011979A1
WO1999011979A1 PCT/DK1997/000366 DK9700366W WO9911979A1 WO 1999011979 A1 WO1999011979 A1 WO 1999011979A1 DK 9700366 W DK9700366 W DK 9700366W WO 9911979 A1 WO9911979 A1 WO 9911979A1
Authority
WO
WIPO (PCT)
Prior art keywords
safety
voltage
flame
cut
thermoelectric
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.)
Ceased
Application number
PCT/DK1997/000366
Other languages
English (en)
Inventor
Christian Eskildsen
Piero Armanni
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 AB
Original Assignee
Electrolux 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 Electrolux AB filed Critical Electrolux AB
Priority to EP97938808A priority Critical patent/EP1027558B1/fr
Priority to DK97938808T priority patent/DK1027558T3/da
Priority to DE69710229T priority patent/DE69710229T2/de
Priority to ES97938808T priority patent/ES2171990T3/es
Priority to PCT/DK1997/000366 priority patent/WO1999011979A1/fr
Priority to AU41130/97A priority patent/AU4113097A/en
Publication of WO1999011979A1 publication Critical patent/WO1999011979A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/10—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples
    • F23N5/102—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/46—Details
    • F23D14/72—Safety devices, e.g. operative in case of failure of gas supply
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C3/00—Stoves or ranges for gaseous fuels
    • F24C3/12—Arrangement or mounting of control or safety devices
    • F24C3/126—Arrangement or mounting of control or safety devices on ranges

Definitions

  • a safety cut-off device is provided.
  • the invention relates to a safety cut-off device for a gas-heated hob comprising a thermocouple and a thermoelectric generator as well as a safety solenoid valve .
  • thermocouple which gives off a voltage when it it is heated by the lit flame, and this voltage is sufficient to deliver a holding current for a solenoid safety valve in the gas supply.
  • a system of this kind may have a push-button to perform the initial mechanical actuation of the solenid valve whereby the gas flows and may be lit, possibly by electronic means, and when the thermocouple has been heated, it sustains the open position of the safety valve.
  • EP 0 635 680 it is known to use a series connection of safety valves to increase the security, and one thermocouple functions as above described and a neighbouring thermeoelectric generator (a series connection of several thermojunctions) supplies an activation and holding current for a separate solenoid valve in series with the first mentioned.
  • thermoelectric voltage generators are large which means that they will supply holding currents for many seconds after a flame has disappeared, irrespective of the reason for the disappearance of the flame. This means that unburnt gas escapes for many seconds which will create an explosion hazard when the admixture of air is suitable. Also, first turning-on of the main flame is relatively slow this way.
  • thermoelectric generator provides the supply voltage for a transistor amplifier controlling the holding current for the safety solenoid valve, said transistor amplifier being controlled by the thermoelectric voltage from the thermocouple in order to cut off the holding current at a predetermined thermoelectric voltage.
  • a preferred embodiment is particular in that the transistor amplifier is a DC coupled common emitter amplifier with the collector connected to the thermeoelectric generator, the emitter to the solenoid, and the base to the thermocouple .
  • An advantageous embodiment further comprises a battery source for providing a short-term actuating voltage for the safety valve.
  • a further advantageous embodiment uses the battery source to power a spark ignition electrode at the hob.
  • Fig. 1 shows the voltages available in thermoelectric junctions and generators
  • Fig. 2 shows a circuit diagram of an amplifier according to the invention
  • Fig. 3 shows the general layout and connections of a device according to the invention.
  • Fig. 1 shows the voltages generated in a thermoelectric junction and in a generator consisting of a series connection of such junctions. It will be seen that the time constant of the series connection is less than the time constant of the single junction, but that the actual voltage of the single junction has an overshoot before it settles at a stable, temperature dependent voltage.
  • the holding voltage of a magnet used in a safety device is low (although the current may be fairly high) , and it is shown in relation to the other voltages present in such appliances.
  • the time constant of the cooling down after a source of heat has disappeared is considerable, and about 6 times as large as the heating-up time constant. Hence a safety cut-out based on the current generated by the voltage of a thermo-junction would let a fair amount of gas escape before the cut-out is effective.
  • Fig. 2 is shown a simple emitter-follower type amplifier in which a thermoelectric generator 1 supplies the drive voltage and the sensing thermojunction 2 provides the input signal to a transistor 3 amplifier.
  • the solenoid 4 of a magnetic safety valve is connected to the emitter of the transistor 3.
  • a silicon transistor will tolerate operating temperatures of ca. 150oC which is ample in practice.
  • the voltages shown graphicaly in Fig. 1 are shown in the schematic, and it will be understood that suitable dimensioning of the base resistor, based on the voltage drops inherent in transistor operation and a knowledge of the resistance of the solenoid for the magnetic valve, will result in a control of the current from the emitter through the solenoid.
  • a cut-off is obtained when the voltage from the thermojunction has fallen only a little with respect to the stable high-temperature condition.
  • Fig. 1 is shown that the gas would continue to flow about 6 times longer, if the safety valve did not release until the voltage had fallen by the thermal time constant alone.
  • Fig. 3 is shown the lay-out "below the top" of a gas hob fitted with electronic ignition of the gas and a safety device according to the invention.
  • a gas burner is generally indicated by the grid at 5, and an ignition electrode 6 is connected to a high-voltage generator 7 supplied by a battery 8 which is remote from the gas burner. Ignition is controlled by the gas valve 9 which is combined with a safety cut-out of the magnetic type. Ordinarily, this valve is actuated by the gas valve during and immediately after ignition, until sufficient holding voltage is available from a thermoelectric source.
  • thermoelectric source Such sources are indicated as a thermojunction 10 and a thermoelectric generator 11. As described above, the thermovoltages generated are fed to an amplifier 12 which is connected to the solenoid in the safety valve 13.
  • thermogenerator and the thermojunction very quickly increase above the holding voltage of the solenoid, and it is not an undue strain on the ignition battery to supply the higher actuation voltage and the solenoid current during the brief period just after ingnition, until the transistor amplifier can take over. This avoids the combination with a mechanical actuation directly from the valve 9.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Combustion (AREA)

Abstract

On décrit des dispositifs à arrêt de sécurité qui utilisent une tension thermoélectrique générée par des capteurs placés dans une flamme. Aussi longtemps que la flamme chauffe le capteur, ce dernier génère un courant de maintien pour une vanne magnétique. Lorsque le capteur se refroidit en raison de l'arrêt de la flamme, la vanne se ferme lorsque le courant de maintien disparaît. Ces dispositifs de sécurité présentent une longue constante de temps pour qu'une quantité de gaz trop importante puisse s'échapper après l'extinction de la flamme. On utilise dans cette invention un capteur présentant une courte constante de temps qui, au moyen d'un transistor, régule un courant généré par un montage en série de thermoéléments. A l'aide de ce système on bénéficie d'un dispositif présentant une plus grande sécurité.
PCT/DK1997/000366 1997-08-28 1997-08-28 Dispositif a arret de securite Ceased WO1999011979A1 (fr)

Priority Applications (6)

Application Number Priority Date Filing Date Title
EP97938808A EP1027558B1 (fr) 1997-08-28 1997-08-28 Dispositif a arret de securite
DK97938808T DK1027558T3 (da) 1997-08-28 1997-08-28 Sikkerhedsafbrydeanordning
DE69710229T DE69710229T2 (de) 1997-08-28 1997-08-28 Sicherheitsstopvorrichtung
ES97938808T ES2171990T3 (es) 1997-08-28 1997-08-28 Dispositivo de corte de seguridad.
PCT/DK1997/000366 WO1999011979A1 (fr) 1997-08-28 1997-08-28 Dispositif a arret de securite
AU41130/97A AU4113097A (en) 1997-08-28 1997-08-28 A safety cut-off device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/DK1997/000366 WO1999011979A1 (fr) 1997-08-28 1997-08-28 Dispositif a arret de securite

Publications (1)

Publication Number Publication Date
WO1999011979A1 true WO1999011979A1 (fr) 1999-03-11

Family

ID=8156223

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1997/000366 Ceased WO1999011979A1 (fr) 1997-08-28 1997-08-28 Dispositif a arret de securite

Country Status (6)

Country Link
EP (1) EP1027558B1 (fr)
AU (1) AU4113097A (fr)
DE (1) DE69710229T2 (fr)
DK (1) DK1027558T3 (fr)
ES (1) ES2171990T3 (fr)
WO (1) WO1999011979A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002040923A1 (fr) * 2000-11-16 2002-05-23 Fernando Teodoro Garcia Systeme d'arret de securite et appareil a gaz dote de ce dernier
EP1251316A3 (fr) * 2001-04-19 2004-03-03 Whirlpool Corporation Dispositif de sécurité pour cuisinières à gaz
AU2002214834B2 (en) * 2000-11-16 2006-11-16 Fernando Teodoro Garcia Shut-off safety system and gas appliance including same
EP3404327A3 (fr) * 2012-05-25 2019-01-16 Eltek S.p.A. Dispositif de commande pour robinets de gaz

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0635680A1 (fr) * 1993-07-20 1995-01-25 SIT LA PRECISA S.r.l. Un actionneur pour un brûleur à gaz avec un sécurité à flamme et un soupape de commande électromagnétique

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0635680A1 (fr) * 1993-07-20 1995-01-25 SIT LA PRECISA S.r.l. Un actionneur pour un brûleur à gaz avec un sécurité à flamme et un soupape de commande électromagnétique

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002040923A1 (fr) * 2000-11-16 2002-05-23 Fernando Teodoro Garcia Systeme d'arret de securite et appareil a gaz dote de ce dernier
AU2002214834B2 (en) * 2000-11-16 2006-11-16 Fernando Teodoro Garcia Shut-off safety system and gas appliance including same
EP1251316A3 (fr) * 2001-04-19 2004-03-03 Whirlpool Corporation Dispositif de sécurité pour cuisinières à gaz
EP3404327A3 (fr) * 2012-05-25 2019-01-16 Eltek S.p.A. Dispositif de commande pour robinets de gaz

Also Published As

Publication number Publication date
AU4113097A (en) 1999-03-22
DK1027558T3 (da) 2002-05-06
DE69710229D1 (de) 2002-03-14
EP1027558B1 (fr) 2002-01-30
EP1027558A1 (fr) 2000-08-16
DE69710229T2 (de) 2002-10-24
ES2171990T3 (es) 2002-09-16

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