EP0388065A2 - Flammendetektionsvorrichtung und -verfahren - Google Patents

Flammendetektionsvorrichtung und -verfahren Download PDF

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Publication number
EP0388065A2
EP0388065A2 EP90302390A EP90302390A EP0388065A2 EP 0388065 A2 EP0388065 A2 EP 0388065A2 EP 90302390 A EP90302390 A EP 90302390A EP 90302390 A EP90302390 A EP 90302390A EP 0388065 A2 EP0388065 A2 EP 0388065A2
Authority
EP
European Patent Office
Prior art keywords
flame
charge
control signal
voltage
probe
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Withdrawn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
EP90302390A
Other languages
English (en)
French (fr)
Other versions
EP0388065A3 (de
Inventor
Clive R. Steer
John W. Defries
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.)
Black Automatic Controls Ltd
Original Assignee
Black Automatic Controls 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 Black Automatic Controls Ltd filed Critical Black Automatic Controls Ltd
Publication of EP0388065A2 publication Critical patent/EP0388065A2/de
Publication of EP0388065A3 publication Critical patent/EP0388065A3/de
Withdrawn legal-status Critical Current

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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
    • F23N5/12—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using ionisation-sensitive elements, i.e. flame rods
    • F23N5/123—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using ionisation-sensitive elements, i.e. flame rods using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/20—Opto-coupler
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2229/00—Flame sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2229/00—Flame sensors
    • F23N2229/12—Flame sensors with flame rectification current detecting means

Definitions

  • the invention relates to apparatus and methods for the detection of the presence of a flame.
  • U.K. Patent No. 1,419,653 there is described a fuel flow control apparatus of the type described herebefore for monitoring a flame generated by a fuel burner.
  • the apparatus described includes a flame probe to which an alternating voltage is applied, the DC component produced by the probe in the presence of a flame being used to charge up a capacitor so as to avoid the requirement for high amplification of the DC component.
  • a sampling means is arranged to periodically discharge the capacitor to produce a periodic output signal indicative of the presence of the flame.
  • a control means is responsive to the output signal to close a valve controlling the flow of fuel to the burner when the output signal indicates that the flame is not present.
  • Such an apparatus suffers the disadvantage however that there is an electrical path between the alternating voltage applied to the flame probe, and the valve which controls the flow of fuel to the burner.
  • the circuit incorporated in the apparatus has to be relatively complex such that this electrical path does not constitute a safety hazard.
  • apparatus for the detection of the presence of a flame comprising circuit means for applying an alternating voltage to a flame probe such that the alternating voltage is partially rectified in the presence of a flame at the probe resulting in the development of a DC voltage component, means responsive to the DC component to cause the accumulation of a corresponding electrical charge in a storage element, means for periodically releasing the charge, and optical coupling means responsive to the released charge to initiate a control signal in a control signal generator, the control signal indicating detection of the flame.
  • the means for applying an alternating voltage to the flame probe is electrically isolated from the control signal, together with any control systems which the control signal is arranged to operate.
  • the alternating voltage may therefore be derived from any suitable source, for example directly from the mains supply or via a transformer.
  • a method of detecting the presence of a flame comprising the steps of applying an alternating voltage to a flame probe to produce a DC voltage component in the presence of a flame at the probe, producing an accumulation of electrical charge in response to the DC component, periodically releasing the accumulated charge, producing an optical signal representative of the released charge, and using the optical signal to initiate the generation of a control signal indicating detection of the flame.
  • a flame sensing probe 2 comprising a pair of electrodes, is connected across the terminals of a voltage generator element 100.
  • Voltage generator element 100 provides an alternating high voltage by means of an AC voltage source 4, the alternating high voltage being applied to the flame sensing probe 2 via a resistor 6 and a capacitor 8.
  • the alternating voltage applied to the probe is partially rectified as a result of the ionizing effect of the flame and a direct current flows between the electrodes of the probe 2.
  • the presence of a flame 10 within a region occupied by the flame sensing probe 2 causes a DC voltage to be developed across capacitor 8.
  • the rectified DC voltage component together with the AC voltage component produced by AC source 4, is applied to isolator element 110 comprising a low pass filter assembly, in particular resistors 12 and 16 and capacitors 14 and 18.
  • isolator element 110 comprising a low pass filter assembly, in particular resistors 12 and 16 and capacitors 14 and 18.
  • the DC voltage component is isolated from that produced by the AC source 4 so that the voltage developed at the output of isolator element 110, that is across capacitor 18, is predominantly DC in character and results from the presence of a flame 10 in the region of probe 2.
  • a pulsed switch element 120 is provided which, in the embodiment shown, includes a transistor 20 to the base of which is presented a periodically varying voltage V1 in such a way that transistor 20 assumes an off-state as voltage V1 approaches zero, the voltage V1 being presented to the base of transistor 20 via a resistor 22 from a source 23 which produces a varying voltage V1 falling to zero at for example 8.3 millisecond intervals where V1 is a 60 Hz mains voltage supply. Transistor 20 will resume an on-state as the voltage V1 rises and at a point determined by the ratio of the values of the resistors 22 and 24 and the peak value of V1.
  • a capacitor 26 will charge from a DC voltage supply V2 via resistor 28 and diode 30.
  • the charge stored in capacitor 26 is discharged through the light emitting diode 32 of opto-coupler 34 which in turn will cause the associated phototransistor 36 to assume an on-state.
  • pulsed switch element 120 causes phototransistor 36 to be pulsed on each time the voltage V1 approaches zero.
  • Control signal generator element 130 includes a thyristor 44 energised via a resistor 45 from voltage V1, to the gate of which is presented the voltage pulse arising from the phototransistor 42, the voltage pulse being presented via resistor 46.
  • the thyristor 44 will latch on and remain in an on-state until such time as the voltage V1 returns to zero and will cause transistor 48 to assume an on-state to operate subsequent control elements 140.
  • the subsequent control elements 140 may comprise any elements whose operation is required to be dependent upon the presence of a flame 10 in the region of flame probe 2.
  • the subsequent control elements may contain a flame relay 50 or an appliance safety shut-off valve.
  • a capacitor (not shown) may be inserted in the signal path between the collector of the transistor 48 and the subsequent control elements 140.
  • Such a capacitor will prevent any short circuit occuring between the collector and emitter of the transistor 48 from leading to a permanent indication that a flame is present.
  • the inclusion of such a capacitor is not essential under present regulations as a permanent flame indication is allowed if this prevents the control elements from initiating an ignition cycle.
  • intervals at which the varying voltage V1 falls to zero may be any suitable time interval sufficient to allow a sufficient amount of charge to build up on the capacitor 18.
  • the pulsed switch means for periodically releasing the charge on the charge storage element which has been accumulated due to the presence of a flame may form part of the circuit for applying an alternating voltage to the flame probe, the opto-coupler means linking the pulsed switch means to the charge storage element thus being omitted.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Control Of Combustion (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
EP19900302390 1989-03-17 1990-03-06 Flammendetektionsvorrichtung und -verfahren Withdrawn EP0388065A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8906235 1989-03-17
GB898906235A GB8906235D0 (en) 1989-03-17 1989-03-17 Flame detection apparatus and method

Publications (2)

Publication Number Publication Date
EP0388065A2 true EP0388065A2 (de) 1990-09-19
EP0388065A3 EP0388065A3 (de) 1991-04-24

Family

ID=10653569

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900302390 Withdrawn EP0388065A3 (de) 1989-03-17 1990-03-06 Flammendetektionsvorrichtung und -verfahren

Country Status (2)

Country Link
EP (1) EP0388065A3 (de)
GB (2) GB8906235D0 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0525345A1 (de) * 1991-07-09 1993-02-03 Robert Bosch Gmbh Vorrichtung und Verfahren zum Überwachen einer Flamme
EP0634611A1 (de) * 1993-07-16 1995-01-18 Johnson Service Company Mehrpegelionenstrommessschaltung
EP0908679A1 (de) * 1997-10-10 1999-04-14 Electrowatt Technology Innovation AG Flammenüberwachungsschaltung
EP1211460A3 (de) * 2000-12-01 2004-04-14 Vaillant GmbH Flammenwächterschaltung

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3348104A (en) * 1964-12-14 1967-10-17 American Gas Ass Bias-controlled a. c.-operable voltage threshold circuit, and systems employing same
DE1526255A1 (de) * 1965-12-22 1970-04-02 May & Christe Gmbh Einrichtung zur UEberwachung von nichtleuchtenden Flammen
GB1419653A (en) * 1972-01-26 1975-12-31 Kidde & Co Walter Fuel flow control apparatus for a burner
JPS55102826A (en) * 1979-02-02 1980-08-06 Toshiba Corp Combustion device
US4370125A (en) * 1980-10-01 1983-01-25 Emerson Electric Co. Control system for blue-flame oil burner

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3348104A (en) * 1964-12-14 1967-10-17 American Gas Ass Bias-controlled a. c.-operable voltage threshold circuit, and systems employing same
DE1526255A1 (de) * 1965-12-22 1970-04-02 May & Christe Gmbh Einrichtung zur UEberwachung von nichtleuchtenden Flammen
GB1419653A (en) * 1972-01-26 1975-12-31 Kidde & Co Walter Fuel flow control apparatus for a burner
JPS55102826A (en) * 1979-02-02 1980-08-06 Toshiba Corp Combustion device
US4370125A (en) * 1980-10-01 1983-01-25 Emerson Electric Co. Control system for blue-flame oil burner

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 4, no. 150 (M-37)(632) 22 October 1980, & JP-A-55 102826 (TOKYO SHIBAURA) 06 August 1980, *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0525345A1 (de) * 1991-07-09 1993-02-03 Robert Bosch Gmbh Vorrichtung und Verfahren zum Überwachen einer Flamme
DE4122636C2 (de) * 1991-07-09 1999-08-12 Bosch Gmbh Robert Vorrichtung und Verfahren zum Überwachen einer Flamme
EP0634611A1 (de) * 1993-07-16 1995-01-18 Johnson Service Company Mehrpegelionenstrommessschaltung
EP0908679A1 (de) * 1997-10-10 1999-04-14 Electrowatt Technology Innovation AG Flammenüberwachungsschaltung
WO1999019672A1 (de) * 1997-10-10 1999-04-22 Siemens Building Technologies Ag Verfahren und vorrichtung zur überwachung einer flamme
US6501383B1 (en) 1997-10-10 2002-12-31 Siemens Building Technologies Ag Method and device for monitoring a flame
EP1211460A3 (de) * 2000-12-01 2004-04-14 Vaillant GmbH Flammenwächterschaltung

Also Published As

Publication number Publication date
EP0388065A3 (de) 1991-04-24
GB8906235D0 (en) 1989-05-04
GB2230632A (en) 1990-10-24
GB9004948D0 (en) 1990-05-02

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