EP0480312B1 - Dispositif de sécurité de courant d'air pour des brûleurs - Google Patents

Dispositif de sécurité de courant d'air pour des brûleurs Download PDF

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Publication number
EP0480312B1
EP0480312B1 EP91116898A EP91116898A EP0480312B1 EP 0480312 B1 EP0480312 B1 EP 0480312B1 EP 91116898 A EP91116898 A EP 91116898A EP 91116898 A EP91116898 A EP 91116898A EP 0480312 B1 EP0480312 B1 EP 0480312B1
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EP
European Patent Office
Prior art keywords
relay
monitoring device
resistor
flow switch
switch
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.)
Expired - Lifetime
Application number
EP91116898A
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German (de)
English (en)
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EP0480312A1 (fr
Inventor
Derk Vegter
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.)
Honeywell BV
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Honeywell BV
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Publication date
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Publication of EP0480312A1 publication Critical patent/EP0480312A1/fr
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    • 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
    • F23N5/184—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel 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
    • F23N5/24—Preventing development of abnormal or undesired conditions, i.e. safety arrangements
    • F23N5/242—Preventing development of abnormal or undesired conditions, i.e. safety arrangements 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
    • F23N2225/00—Measuring
    • F23N2225/04—Measuring pressure
    • F23N2225/06—Measuring pressure for determining flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2231/00—Fail safe
    • F23N2231/10—Fail safe for component failures
    • 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

Definitions

  • the invention relates to an air flow monitoring device for burner systems according to the preamble of claim 1. It is common to switch on the fuel supply to the burner only when the proper operation of the blower supplying the combustion air has been determined with the aid of a flow switch. Flow switches with a changeover contact are known for this purpose, the normally closed contact being used for the initial self-monitoring in order to determine whether the flow switch is already closed, that is to say defective, when the fan is stopped.
  • the disadvantage here is the need for three supply lines to the flow switch, which can lead to errors in the installation of the burner system and in its maintenance and repairs, for example by mixing up the connections.
  • EP-A 0 197 334 shows a circuit for controlling a fuel-heated heat source, in which the flow switch has only two supply lines and is nevertheless subject to self-monitoring.
  • the coil of a relay is connected to the operating voltage via a resistor, the relay coil being a capacitor on the one hand and the flow switch on the other are connected in parallel.
  • a changeover switch In series with the relay coil is a changeover switch such that the relay has a self-holding circuit which separates the relay coil from the capacitor and from the flow switch when the relay is self-holding.
  • an electronic switch is connected in series to ground. The switch-on signal for the burner is picked up at the connection point between the relay coil and the changeover switch.
  • the object of the invention is to provide an intrinsically safe air flow monitoring device, the flow switch of which only requires two connections, with less circuit complexity. This succeeds with the invention characterized in claim 1. Advantageous refinements result from the subclaims.
  • the monitoring device is supplied with AC voltage from the 220V network. It is connected with its phase line N via a mains switch S to the live line of the AC mains voltage, the ground line of which is designated by O.
  • the fan F is connected to the supply voltage lines N and O via the relay contact rl1 of an auxiliary relay RL1 connected in series with it. Between the connection point of relay contact rl1 and fan F on the one hand and the output A of the monitoring circuit on the other hand, the contact sp of the flow switch is switched on. This is closed in a conventional manner by the air flow generated by the fan F as soon as it reaches a predetermined minimum throughput.
  • the occurrence of a signal at output A indicates that the required air flow is present and that the burner can be started.
  • This signal at output A can be used, for example, to open a gas valve or to start a conventional burner control circuit which determines the individual steps of a burner cycle.
  • the flow switch sp is connected in series with the fan F, and here the field winding RL1 of an AC relay is connected directly in parallel with this series connection.
  • the normally open contact rl1 of the relay RL1 is switched on.
  • the high-resistance resistor R1 is connected in parallel to the series connection of relay contact rl1 and flow switch sp.
  • the switch-on signal for a connected burner or its control circuit is taken from connection point P3 between resistor R1 and flow switch sp.
  • the mains switch S which is controlled by a thermostat, closes, the mains voltage is connected to the series connection of resistor R1 and relay RL1.
  • the fan F is separated from the mains by the two working contacts rl1 and sp.
  • the resistance value of the resistor R1 of, for example, 2200 ohms is small compared to the impedance of the relay RL1 of, for example, 25000 ohms.
  • the relay RL1 picks up and closes its contact rl1.
  • the fan F starts up.
  • the flow switch sp closes, whereby the mains voltage then reaches the connection point P3 and the output A directly via the now closed contacts rl1 and sp.
  • the series connection of the flow switch sp and the fan F forms a parallel circuit to the relay RL1.
  • the embodiment according to FIG. 2 differs from that according to FIG. 1 on the one hand in that a highly sensitive direct current relay RL1 is used instead of an alternating current relay and is connected to the connection point P3 via a rectifier bridge circuit D1 to D4.
  • the excitation winding VG of a fuel valve V is connected in series with the relay circuit and the relay winding RL1 a Zener diode Z connected in parallel.
  • the resistor R1 has a value of 15000 ohms
  • the excitation winding VG of the fuel valve has an impedance of 1000 to 5000 ohms at an operating voltage of 186V.
  • the blocking voltage of the Zener diode Z is 47V
  • the operating voltage of the relay RL1 is approximately 48V.
  • the resistance value of the resistor R1 is significantly larger than the impedance of the fan F.
  • the current flows bypassing the resistor R1 via the closed contacts rl1 and sp to point P3 and from there through the series connection of relay RL1 and gas valve VG.
  • the voltage at the relay RL1 is limited by the Zener diode Z, which the excess current on Relay RL1 bypassed and creates a constant voltage at relay RL1.
  • the nominal voltage at the excitation coil of the gas valve GV should therefore be 186 volts. This increased current opens the gas valve VG.
  • the occurrence of the mains voltage at the connection point P3 does not directly apply the excitation current for the relay RL1, but rather a circuit arrangement which reduces the current consumption of the relay RL1 is interposed.
  • the relay RL1 is connected in series with an electronic switch T1 on one side and a current limiting resistor R7 and a rectifier D2 on the other side between the power supply lines N and O.
  • a resistor R8 In parallel with the electronic switch T1 there is a resistor R8 which, in series with the relay winding RL1 and as a result of the half-wave current flowing through the relay winding RL1, the limiting resistor R7 and the rectifier D2 when the transistor T1 is blocked, gives rise to a certain voltage at point P1.
  • the half-wave current cannot trigger the relay RL1.
  • a timer consisting of a charging capacitor C2 with a resistor R4 connected in parallel, a series resistor R3 and a differential amplifier U1, is also connected to the mains line N via a second rectifier D1 and a high-resistance resistor R1.
  • the output P2 of the Amplifier U1 is connected to the base of transistor T1 via a resistor R9.
  • a resistor R6 is connected between the non-inverting input (+) and the output P2 of the amplifier, and a resistor R5 lies between the input mentioned and the ground line O.
  • the inverting input (-) is at the connection point of the RC timer C2 / R4 with the series resistor R3.
  • a resistor R2 is connected in parallel to the series connection of fan F and flow switch sp.
  • the supply voltage + V is for example + 22V and the voltage -V, for example -5V.
  • the circuit works as follows: When the mains switch S is closed, a half-wave current flows through the rectifier D2 and the resistor R7 to the capacitor C1 and charges it, for example, to -24V. This value is determined by the size of the aforementioned half-wave current and the series resistance of RL1 and R8. As mentioned, this current is not sufficient to trigger the relay RL1. Simultaneously with the activation of the charging current for the capacitor C1, when the mains switch S is closed, the timer R3, R4, C2, U1 is switched on via the resistor R1 and the rectifier D1 by charging the capacitor C2 via the resistor R3. The voltage across capacitor C2 is also at the inverting input (-) of the differential amplifier U1.
  • a bias voltage which is determined by the voltage divider consisting of the resistors R5 and R6, is fed to its non-inverting input.
  • the capacitor C1 discharges through the relay winding RL1 and triggers the relay.
  • the relay RL1 is held in the addressed state by a holding current which flows through the transistor T1 or flows through the resistor R8 when it is blocked. This holding current could not trigger relay RL1.
  • a high-resistance circuit can be connected to output A, for example, which realizes a specific pre-purge time and then switches on the excitation winding of a fuel valve. This high-resistance circuit is simulated by resistor R2.
  • the timer will not start because its input voltage between point P3 and ground is short-circuited via the series connection of the incorrectly closed flow switch sp and the relatively low-impedance motor winding of the fan F. .
  • the internal resistance of the motor is, for example, 500 ohms, while the input resistance R1 is significantly higher and, as mentioned above, is for example 220 kOhm. If the timer does not respond, there is no switch-on voltage for transistor T1, so that relay rl1 cannot respond either. A faulty timer or short-circuited transistor T1 means that the capacitor C2 cannot be charged and therefore the relay RL1 cannot respond. The circuit is therefore intrinsically safe.

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

Claims (12)

  1. Dispositif de contrôle de l'écoulement d'air dans des installations à brûleur, comprenant un ventilateur (F) et un interrupteur d'écoulement (sp) qui peut être actionné par l'écoulement d'air, et lors de la fermeture duquel un brûleur est mis en marche, par exemple par l'ouverture de l'alimentation en combustible, caractérisé
    a) en ce que l'interrupteur d'écoulement (sp) est monté en série avec le ventilateur (F), et le circuit d'excitation d'un relais (RL1) est monté en parallèle avec ce montage série;
    b) en ce qu'un contact de travail (r11) du relais (RL1) est monté entre le point de connexion (P4) du ventilateur (F) et de l'interrupteur d'écoulement (sp) d'une part, et une ligne d'alimentation en courant (N) d'autre part;
    c) en ce qu'une résistance (R1) est montée en parallèle avec le montage série du contact de relais (r11) et de l'interrupteur d'écoulement (sp);
    d) en ce que l'impédance du ventilateur (F) est faible par rapport à celle de la résistance (R1);
    e) en ce que l'impédance du ventilateur (F) est faible par rapport à celle du circuit d'excitation du relais; et
    f) en ce que le signal de mise en marche (A) pour le brûleur, est prélevé à la borne de connexion (P3) de l'interrupteur d'écoulement (sp), éloignée du ventilateur (F).
  2. Dispositif de contrôle selon la revendication 1, caractérisé en ce que la valeur ohmique de la résistance (R1) est faible par rapport à l'impédance du relais (RLl) (figure 1).
  3. Dispositif de contrôle selon la revendication 2, caractérisé en ce que le relais (RL1) est un relais à courant alternatif.
  4. Dispositif de contrôle selon la revendication 1, caractérisé en ce que l'enroulement d'excitation (VG) d'une vanne de combustible (V) est monté en série avec la bobine de relais (RL1), et en ce qu'avec ce montage série et monté en parallèle le montage série de l'interrupteur d'écoulement (sp) et du ventilateur (F) (figure 2).
  5. Dispositif de contrôle selon la revendication 4, caractérisé en ce que le relais (RL1) est un relais à courant continu, et est monté, par l'intermédiaire d'un circuit à pont redresseur (D1 à D4), entre l'interrupteur d'écoulement (sp) et l'enroulement d'excitation (VG) de la vanne de combustible.
  6. Dispositif de contrôle selon la revendication 5, caractérisé en ce qu'une diode Zener (Z) est montée en parallèle avec l'enroulement du relais (RL1)
  7. Dispositif de contrôle selon l'une des revendications 4 à 6, caractérisé par un choix tel de la sensibilité de réponse du relais (RL1) et de l'enroulement d'excitation (VG) de la vanne de combustible (V), que lorsque l'interrupteur d'écoulement (sp) est ouvert, le courant limité par la résistance (R1), conduit au déclenchement du relais (RL1), mais non à l'ouverture de la vanne de combustible (V).
  8. Dispositif de contrôle selon la revendication 1, caractérisé
    a) en ce que d'une part, l'enroulement d'excitation (RL1) du relais, en série avec un commutateur électronique (T1), est raccordé à la ligne d'alimentation en courant (N, O), et d'autre part, l'entrée d'une horloge (R3, R4, C2, U1) est raccordée au point de connexion (P3) de la résistance (R1) et de l'interrupteur d'écoulement (sp);
    b) en ce que la sortie (P2) de l'horloge est raccordée à l'électrode de commande du commutateur électronique (T1); et
    c) le montage série de l'interrupteur d'écoulement (sp) et du ventilateur (F), est monté en parallèle avec l'entrée (P3) de l'horloge.
  9. Dispositif de contrôle selon la revendication 8, caractérisé en ce que l'horloge (R3, R4, C2, U1) d'une part, et le relais (RL1) d'autre part, sont raccordés, chacun par l'intermédiaire d'un redresseur (D1, D2), à une ligne d'alimentation en courant alternatif (N, O), et en ce qu'un condensateur d'accumulation (C1) est monté en parallèle avec le montage série de l'enroulement de relais (RL1) et du commutateur électronique (T1).
  10. Dispositif de contrôle selon la revendication 8 ou 9, caractérisé en ce qu'avec le montage série du commutateur électronique (T1) et de l'enroulement de relais (RL1), est montée en série une résistance (R7), dimensionnée de manière telle, que le courant circulant lorsque le commutateur (T1) est fermé, soit suffisant en tant que courant de maintien du relais, toutefois trop faible en tant que courant de déclenchement.
  11. Dispositif de contrôle selon l'une des revendications 8 à 10, caractérisé en ce que l'horloge comporte un condensateur de charge (C2), ainsi qu'un amplificateur différentiel (U1) dont la sortie (P2) est reliée à l'électrode de commande du commutateur électronique (T1).
  12. Dispositif de contrôle selon l'une des revendications 8 à 11, caractérisé en ce que l'enroulement de relais (RL1) est raccordé à la ligne d'alimentation en courant (N) par l'intermédiaire d'une résistance de limitation du courant (R7).
EP91116898A 1990-10-10 1991-10-04 Dispositif de sécurité de courant d'air pour des brûleurs Expired - Lifetime EP0480312B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP90119383 1990-10-10
EP90119383 1990-10-10

Publications (2)

Publication Number Publication Date
EP0480312A1 EP0480312A1 (fr) 1992-04-15
EP0480312B1 true EP0480312B1 (fr) 1994-07-27

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EP91116898A Expired - Lifetime EP0480312B1 (fr) 1990-10-10 1991-10-04 Dispositif de sécurité de courant d'air pour des brûleurs

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EP (1) EP0480312B1 (fr)
DE (1) DE59102338D1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9310458U1 (de) * 1993-03-05 1994-06-30 Landis & Gyr Business Support Ag, Zug Elektronische Steuer- bzw. Regeleinrichtung für Gasbrenner von Heizungsanlagen
EP0698767B1 (fr) * 1994-08-24 1996-10-30 Honeywell B.V. Circuit de commande d'un brûleur à gaz avec contrÔle de l'alimentation d'air comburant
DE59700550D1 (de) * 1997-01-22 1999-11-18 Honeywell Bv Steuerschaltung für Gasventil mit Überwachung der Verbrennungsluftzufuhr
ATE266839T1 (de) * 2000-10-06 2004-05-15 Honeywell Bv Steuerschaltung

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH543707A (de) * 1972-04-13 1973-10-31 Landis & Gyr Ag Steuerschaltung für Öl- und Gasbrenner
US4243372A (en) * 1979-02-05 1981-01-06 Electronics Corporation Of America Burner control system
US4403942A (en) * 1980-11-18 1983-09-13 Carrier Corporation Self-checking safety switch control circuit
DE3677398D1 (de) * 1985-03-13 1991-03-14 Vaillant Joh Gmbh & Co Schaltung zur steuerung einer brennstoffbeheizten waermequelle.

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Publication number Publication date
EP0480312A1 (fr) 1992-04-15
DE59102338D1 (de) 1994-09-01

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