EP0573223A1 - Appareils de chauffage - Google Patents

Appareils de chauffage Download PDF

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Publication number
EP0573223A1
EP0573223A1 EP93304163A EP93304163A EP0573223A1 EP 0573223 A1 EP0573223 A1 EP 0573223A1 EP 93304163 A EP93304163 A EP 93304163A EP 93304163 A EP93304163 A EP 93304163A EP 0573223 A1 EP0573223 A1 EP 0573223A1
Authority
EP
European Patent Office
Prior art keywords
gas burner
gas
causing
energised
pilot
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Withdrawn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
EP93304163A
Other languages
German (de)
English (en)
Inventor
Richard Arthur George Kinge
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.)
BLUE CIRCLE HEATING Ltd
Original Assignee
BLUE CIRCLE HEATING 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 BLUE CIRCLE HEATING Ltd filed Critical BLUE CIRCLE HEATING Ltd
Publication of EP0573223A1 publication Critical patent/EP0573223A1/fr
Withdrawn legal-status Critical Current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
    • F23N5/20—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays
    • F23N5/203—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N2005/181—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of air
    • F23N2005/182—Air flow switch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/22—Timing network
    • F23N2223/26—Timing network with capacitors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2227/00—Ignition or checking
    • F23N2227/22—Pilot burners
    • F23N2227/24—Pilot burners the pilot burner not burning continuously
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2227/00—Ignition or checking
    • F23N2227/28—Ignition circuits
    • F23N2227/30—Ignition circuits for pilot burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2227/00—Ignition or checking
    • F23N2227/36—Spark ignition, e.g. by means of a high voltage
    • 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
    • F23N2233/00—Ventilators
    • F23N2233/06—Ventilators at the air intake
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/14—Fuel valves electromagnetically operated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/18—Groups of two or more valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel

Definitions

  • This invention relates to heating appliances, and more specifically to gas fired heating appliances such as hot water boilers for gas central heating systems. It is especially concerned with control systems for use in such heating appliances.
  • a heating appliance control system needs to provide that the safety of such an appliance is not compromised by the failure of any single component. All single component faults should result in a failure of the appliance to light so that it is impossible for any failed part to go unnoticed in a state which could be hazardous. Note that in this regard, certain failure modes of components are generally accepted as being impossible such as the short circuit condition for spiral wound resistors and the welding of relay contacts which do not SWITCH current.
  • a heating appliance comprising gas burner means, ignition means for lighting said gas burner means, flame detector means for detecting the presence of flame on said gas burner means, and a control system for controlling the operation thereof, said control system comprising a resistive/capacitive timing circuit which is responsive to a demand for said appliance to be operated for causing a varying voltage signal to be generated, comparator means for comparing said varying voltage signal with a reference signal and for affording a comparator signal effective for causing gas to be supplied to said gas burner means and for causing said ignition means to be energised, said comparator means also being effective for causing the reference signal applied thereto to be changed, and is effective for comparing said varying voltage signal with said changed reference signal whereby, if a flame is detected by said flame detector means before said comparator means again operates, the gas supply to said gas burner means is maintained and the energisation of said ignition means is terminated, and if a flame is not detected by said flame detector means, said comparator means is again operated and
  • said gas burner means comprises a main gas burner and a pilot gas burner, said ignition means being effective for lighting said pilot gas burner and said flame detection means being effective for detecting a flame on said pilot gas burner, it being arranged that said main gas burner is supplied with gas when said pilot burner is supplied with gas and when said ignition means is de-energised.
  • a main gas valve may be provided for supplying gas to said main gas burner, and a pilot gas valve may be provided for supplying gas to said pilot gas burner.
  • said demand for said appliance to be operated is constituted by an electrical mains signal applied to said control system, and power supply means may be provided responsive to the electrical mains signal for affording a d.c. electrical supply for energising said control system.
  • said resistive/capacitive timing circuit is connected to said d.c. electrical supply for causing capacitor means thereof to be charged in response to said demand being received, said comparator means being effective for comparing the voltage of said capacitor means with said reference signal afforded by potential divider means, and for causing a first relay to be energised, said first relay causing a second relay to be energised, for connecting one line of said electrical mains signal to said pilot gas valve and said main gas valve, and for causing said second relay to be latched in its energised condition.
  • said second relay causes said reference signal afforded by said potential divider means to be changed whereby said comparator means causes said first relay to be de-energised, said first relay in its de-energised condition being effective for causing said pilot gas valve to be energised to supply gas to said pilot gas burner, and for causing said ignition means to be energised for causing said pilot gas burner to be lit.
  • an output from said flame detection means indicating the presence of a flame on said pilot gas burner is effective for causing the main gas valve to be energised for supplying gas to said main gas burner, for causing said ignition means to be de-energised, and for causing said capacitor means to be discharged whereby said comparator means maintains said first relay in its de-energised condition to maintain energisation of said main gas valve and said pilot gas valve.
  • said comparator means in response to a comparison of said varying signal and said changed reference signal, and in the absence of an output form said flame detector means indicative of no flame being present on said pilot gas burner, causes said first relay to be energised to cause said pilot gas valve and said main gas valve to be de-energised to prevent gas flow to the pilot gas burner and the main gas burner.
  • a heating appliance in accordance with the present invention may comprise a fan for providing combustion air to said gas burner means, in which case said control circuit may comprise an air proving switch responsive to air from said fan for controlling the operation of said gas burner means.
  • said resistive/capacitive timing circuit is connected to said d.c. supply for causing an initially charged capacitor means thereof to be discharged in response to said demand being received, and to be further discharged when said reference signal is changed.
  • said resistive/capacitive timing circuit is connected to said d.c. supply for causing capacitor means thereof to be charged or discharged in response to said demand being received, the charge or discharge, as the case may be, being reversed when said reference signal is changed.
  • a heating appliance in accordance with the present invention includes a control system which employs a self checking lockout timer circuit which utilises its components in a timing function prior to commencement of the ignition process so that it is established that its operation is healthy before there is any subsequent need to lockout due to ignition failure.
  • the timing function is preferably obtained by charging a capacitor via a resistor until a defined reference voltage is reached. Upon satisfactorily reaching this first "time-out", the reference is changed so that the same timing components are re-used as the capacitor charges towards a new voltage.
  • the time taken for this self checking may be made long enough to act as a "rapid cycle limiter" to prevent instances where this type of operation could be a nuisance to the user.
  • a control system for a gas heating appliance the appliance having a main gas burner (not shown) which is supplied with gas via a main gas valve solenoid 20, a pilot gas burner (not shown) which is supplied with gas via a pilot gas valve solenoid 19, a flame detector 9 for detecting the presence of a flame at the pilot gas burner (not shown), and a spark generator 21 which, when energised, causes one or more sparks to be generated in the vicinity of the pilot gas burner (not shown) to cause it to light.
  • a main gas burner (not shown) which is supplied with gas via a main gas valve solenoid 20
  • a pilot gas burner (not shown) which is supplied with gas via a pilot gas valve solenoid 19
  • a flame detector 9 for detecting the presence of a flame at the pilot gas burner (not shown)
  • a spark generator 21 which, when energised, causes one or more sparks to be generated in the vicinity of the pilot gas burner (not shown) to cause it to light.
  • the control system to be described with reference to Fig. 1 includes a number of relay coils, as will be described, and it should be appreciated that the relay contact positions are shown in the conventional de-energised state, and dotted lines are used to indicate which relay contacts are influenced by each relay coil.
  • the control system shown in Fig. 1 comprises a NEUTRAL supply line N and, when there is a "call for heat", e.g. from a room thermostat or time switch, a switched live mains supply is applied to supply line L.
  • a "call for heat" e.g. from a room thermostat or time switch
  • an auxiliary d.c. supply rail 24 is energised by a d.c. power supply 17.
  • the power supply circuit 17 could, for example, take the form of a mains transformer and rectifier or a capacitor dropper circuit.
  • the main gas valve solenoid 20 and the pilot gas valve solenoid 19 are both isolated from the supply line L by means of relay contacts 3 so that no gas is supplied to either the main gas burner (not shown) or the pilot gas burner (not shown).
  • relay coil 1 causes the voltage on the non-inverting input of comparator 15, defined by resistors 13,14 etc., to be pulled up to a new voltage by the current flow through resistor 10 thus de-energising relay coil 4.
  • This change to the timer reference voltage on the non-inverting input of comparator 15, resets its output state but leaves the timing capacitor 12 charging so that satisfactory operation of the timer at this point signals its certain subsequent operation when the capacitor 12 voltage reaches the new reference voltage.
  • the contacts 3 on relay coil 1 and the now released contacts 5 of relay coil 4 provide energisation of the pilot gas valve solenoid 19. Energisation of the spark generator circuit 21 is also provided by the small current which flows via the main gas valve solenoid 20, which current is insufficient to operate solenoid 20.
  • capacitor 12 continues its charge towards the neutral rail N via resistor 11.
  • the flame detector 9 will detect the flame and will de-energise relay 6 causing the relay contacts 8 to operate and causing the spark generator 21 to be short circuited to halt the sparks, the short circuiting of the spark generator 21 causing full current to be applied to the main gas valve solenoid 20 to provide full rate gas to the main gas burner (not shown) which will then be lit from the pilot burner. Normal operation of the appliance can now continue since contacts 7, also on relay coil 6, prevent lockout by holding capacitor 12 discharged via resistors 16 and 18.
  • relay coil 4 will be energised thus causing relay contacts 5 to halt the generation of sparks and the supply of gas.
  • the appliance will now remain in this lockout condition until the "call for heat" is interrupted and restored to reattempt light-up. If the flame detector 9 subsequently indicates flame (due to perhaps an intermittent fault on the flame detector 9) then resistor 16 pulls capacitor 12 rapidly up to the neutral rail N, via relay contacts 5, to prevent the release of the relay coil 4 which would allow the system to restore gas and ignition etc.
  • control system so far described is advantageous in that should a malfunction occur, the control system locks out to prevent the generation of sparks and the supply of gas to the gas burners.
  • diode 25 halts the charge of the capacitor 12 at the timer proving voltage, so that the ignition period is not shortened by excessive delay in the operation of the air pressure switch 23.
  • the operation of the arrangement of Fig. 2 is in other respects the same as that of Fig. 1.
  • Figs. 1 and 2 which have been described, operate satisfactorily, but in some situations degradation of the capacitor 12 can occur e.g. due to leakage with age, and can result in the timing periods being increased with possible adverse affects. This may be overcome by reconnecting the capacitor 12 between the neutral rail N and the inverting input of the comparator 15 and by arranging that the capacitor 12 is precharged prior to the normal operation of the system so that it discharges during the timing periods. This provides the benefit that if the capacitor 12 degrades and becomes leaky with age, the timing periods before lockout will safely be reduced.
  • a "low cost" variation in the arrangement of Fig. 2 is produced if capacitor 12 is connected between the neutral rail N and the inverting input of comparator 15 without any additional precharging circuitry added.
  • the capacitor 12 voltage will move towards the initial “reference” on the non-inverting input of comparator 15 due to the current flow through diode 25. Once air flow is proved by the air pressure switch 23, the capacitor 12 will discharge towards the neutral rail N to provide the fail safe ignition timing. It is necessary, in this compromise arrangement, to form resistor 11 from at least two parallel components so that any failure will not jeopardise a controlled safety lockout.
  • a further example of a possible variation of the arrangements which have been described, is the reversal of the capacitor 12 charge/discharge at the point of satisfactorily proving the first "time-out" period. This charge then discharge of the capacitor 12 will also ensure that capacitor degradation does not extend the time to lockout.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Combustion (AREA)
EP93304163A 1992-05-30 1993-05-28 Appareils de chauffage Withdrawn EP0573223A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9211829 1992-05-30
GB929211829A GB9211829D0 (en) 1992-05-30 1992-05-30 Heating appliances

Publications (1)

Publication Number Publication Date
EP0573223A1 true EP0573223A1 (fr) 1993-12-08

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Family Applications (1)

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EP93304163A Withdrawn EP0573223A1 (fr) 1992-05-30 1993-05-28 Appareils de chauffage

Country Status (2)

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EP (1) EP0573223A1 (fr)
GB (2) GB9211829D0 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6507761B1 (en) 1997-12-02 2003-01-14 Rheem Manufacturing Company Boiler system ignition sequence detector and associated methods of protecting boiler systems

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2332966B1 (es) * 2007-03-20 2011-01-12 Fol. S.R.L. Dispositivo de seguridad para instalarlo en andamiajes metalicos fijos con el fin de evitar caidas de altura durante las operaciones de montaje y desmontaje de los andamios.
ES2334605B1 (es) * 2007-08-07 2011-02-10 Bsh Electrodomesticos España, S.A. Circuito de dispositivo de encendido.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2078398A (en) * 1980-06-18 1982-01-06 Danfoss As Electric control circuit for a fuel-fired burner
EP0482857A1 (fr) * 1990-10-22 1992-04-29 Honeywell Inc. Commande de brûleur de type à brûleur pilote à fonctionnement intermittent avec un seul relais de commande

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2078398A (en) * 1980-06-18 1982-01-06 Danfoss As Electric control circuit for a fuel-fired burner
EP0482857A1 (fr) * 1990-10-22 1992-04-29 Honeywell Inc. Commande de brûleur de type à brûleur pilote à fonctionnement intermittent avec un seul relais de commande

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 6, no. 74 (M-127)11 May 1982 & JP-A-57 012 219 ( TOSHIBA ) 22 January 1982 *
PATENT ABSTRACTS OF JAPAN vol. 7, no. 1 (M-183)6 January 1983 & JP-A-57 161 421 ( MATSUSHITA DENKI SANGYO ) 5 October 1982 *
PATENT ABSTRACTS OF JAPAN vol. 7, no. 257 (M-256)16 November 1983 & JP-A-58 140 517 ( NORITSU ) 20 August 1983 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6507761B1 (en) 1997-12-02 2003-01-14 Rheem Manufacturing Company Boiler system ignition sequence detector and associated methods of protecting boiler systems
US6600960B1 (en) 1997-12-02 2003-07-29 Rheem Manufacturing Company Boiler system ignition sequence detector and associated methods of protecting boiler systems

Also Published As

Publication number Publication date
GB2267377B (en) 1996-01-03
GB9311018D0 (en) 1993-07-14
GB9211829D0 (en) 1992-07-15
GB2267377A (en) 1993-12-01

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