EP0439417B1 - Safety device for the operating of a burner - Google Patents

Safety device for the operating of a burner Download PDF

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Publication number
EP0439417B1
EP0439417B1 EP91420025A EP91420025A EP0439417B1 EP 0439417 B1 EP0439417 B1 EP 0439417B1 EP 91420025 A EP91420025 A EP 91420025A EP 91420025 A EP91420025 A EP 91420025A EP 0439417 B1 EP0439417 B1 EP 0439417B1
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EP
European Patent Office
Prior art keywords
capacitor
circuit
burner
thermocouple
voltage
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
EP91420025A
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German (de)
French (fr)
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EP0439417A1 (en
Inventor
François Danjou
Gilles Boiron
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Constructions Electriques R V SA
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Constructions Electriques R V SA
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Publication of EP0439417A1 publication Critical patent/EP0439417A1/en
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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
    • F23N5/02—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
    • 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
    • F23N2227/36—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
    • F23N2237/00—Controlling
    • F23N2237/14—Controlling burners with gasification or vaporizer elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2239/00—Fuels
    • F23N2239/04—Gaseous fuels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2241/00—Applications
    • F23N2241/08—Household apparatus

Definitions

  • the present invention relates to the technical means used to control the supply of gaseous fuel to a burner in the general sense, of a domestic or industrial character and capable of equipping all the devices or installations for which they constitute a source of production. heat.
  • the invention relates, more specifically, to devices adapted to assume a safety function when the burner is lit, on the one hand, and when the burner is turned off, on the other hand.
  • thermocouple rises in the presence of a flame, so that the thermocouple produces an excitation current from a coil adapted to maintain the solenoid valve in the open position. . If no flame appears, the supply solenoid valve is closed at the end of the ignition time, insofar as the thermocouple produces no holding current of the coil.
  • thermocouple despite the absence of flame, can continue to ensure the opening of the solenoid valve, for the time necessary for its cooling.
  • Such a drawback of the operation of the safety device appears, in particular, during a hot start of the burner beyond the ignition delay and at each stop of operation of the burner.
  • the present invention therefore aims to remedy the drawbacks stated above by proposing a safety device capable of ensuring, in complete safety, the operation of the solenoid valve at each start-up, while making it possible to block the action of the thermocouple as soon as a burner operation stop occurs.
  • the invention also aims to provide a device suitable for ensuring an effective safety function of the operation of the burner, whatever the fault occurring on a component of the device according to the invention.
  • the invention also aims to offer a safety device that is simple to use and has a reduced manufacturing cost.
  • the switching means comprise a relay mounted in series with the capacitor, by means of a diode mounted to prevent excitation of the relay during charging of the capacitor and to authorize excitation of the relay during discharging the capacitor
  • the device comprises a relay supplied by the circuit and the two contacts of which are mounted on the terminals of a thermocouple, so as to close the thermocouple circuit as soon as an ignition order intervenes and to inhibit operation of the thermocouple as soon as a burner shutdown order occurs.
  • Fig. 1 illustrates an example of application of the security device according to the invention.
  • Fig. 2 illustrates an alternative embodiment of a safety device according to the invention ensuring an ignition delay.
  • Fig. 3 is a voltage curve as a function of time, making it possible to explain the operation of the device according to the invention.
  • Fig. 4 illustrates another alternative embodiment of the security device according to the invention.
  • Fig. 1 illustrates, by way of example, an installation comprising a safety system 1 for the operation of a burner 2 , constituting, in the example illustrated, a burner of an oven.
  • the burner 2 is capable of being supplied with gaseous fuel via a line 3 on which is mounted a solenoid valve 4 which is controlled by the system 1 .
  • the solenoid valve 4 represented schematically, comprises, in a conventional manner, a shutter 5 intended to be moved from its seat 6 , by means of a rod 7 associated with an excitation coil 8 , making it possible to supply the burner with fuel.
  • the shutter 5 is associated with an excitation coil 9 , adapted to maintain the shutter 5 in the open position.
  • This coil 9 is controlled, by means of a means 11 for detecting the presence of a flame, advantageously formed by a thermocouple generating an excitation current of the coil when the temperature of the thermocouple has risen to a given temperature.
  • the burner 2 is provided, in a conventional manner, with an ignition electrode 12 making it possible to ignite the fuel using high-voltage sparks generated and controlled by a suitable means which is integrated, in the example illustrated, in security system 1 .
  • the safety system 1 which comprises a circuit 1 a suitable for controlling the solenoid valve 4 and the ignition electrode 12 , comprises, in accordance with the invention, a timed control system 1 b adapted for allow, following a command signal from the burner operation, the opening of the solenoid valve during a determined ignition time Ta , for example of the order of fifteen seconds.
  • the timed control system 1b comprises a circuit 14 for producing a low-voltage DC power supply, from a supply network.
  • the supply network is of the single-phase type and delivers an alternating voltage of the order of 220 volts, through a phase line L1 and a neutral line L2 .
  • the phase line L1 is provided with a contact 16 of a thermostat which makes it possible to give the order ensuring the operation control of the burner.
  • Line L1 also comprises, between contact 16 and circuit 14 , an assembly formed by a capacitor 17 connected in series with a resistor 18 .
  • the circuit 14 which constitutes a rectifier, delivers, in the example illustrated, a voltage corresponding to the half-waves positive of the supply voltage produced by the network.
  • the circuit 14 is formed by a first diode 19 , the anode of which is connected to the capacitor 17 and to the cathode of a second diode 21 .
  • the cathode of the diode 19 is connected, via a capacitor 22 , to the neutral.
  • a relay 48 is mounted between the anode of the diode 21 and the common point between the neutral and the capacitor 22 .
  • the relay 48 which is connected in parallel with a capacitor 49 , comprises two associated contacts 48 a , 48 b mounted in the circuit of the thermocouple 11 , in parallel with one another.
  • One of the terminals of the thermocouple 11 is connected, via the coil 9 , to a common point of the two contacts, while the other terminal of the thermocouple is connected to the other common point of the contacts.
  • the circuit 14 is intended to supply or charge, through a resistor 24 connected to the cathode of the diode 19 , a capacitor 25 which is connected to the neutral using a diode 26 mounted in its direct direction.
  • the capacitor 25 is associated with a circuit 27 ensuring, when the charging voltage of the capacitor 25 reaches a threshold voltage fixed by the circuit 27 , the discharge of the capacitor 25 to a given value, so that the discharge time of the capacitor corresponds to the ignition duration Ta .
  • Such a discharge circuit controlled at threshold voltage 27 comprises a flip-flop 28 mounted in parallel on the capacitor 25 and a threshold-voltage means 29 ensuring the triggering of the flip-flop when the charge voltage of the capacitor 25 reaches the fixed threshold voltage by means 29 which is constituted, in the example illustrated, by a Zener diode.
  • the flip-flop 28 consists of a first 31 and a second 32 direct-coupled transistors.
  • the emitter of the first transistor 31 is connected, via a resistor 33 , to the common point between the resistor 24 and the capacitor 25 .
  • the collector of transistor 31 drives the base of the second transistor 32 which comprises, between its base and its emitter, an assembly formed by a capacitor 35 mounted in parallel with a resistor 36 .
  • the emitter of transistor 32 which is connected to neutral, is connected to the anode of Zener diode 29 , while the collector of transistor 32 drives the base of transistor 31 and is connected, on the one hand, to the cathode of Zener diode 29 and, on the other hand, via a resistor 37 , at the point in common between the capacitor 22 , the diode 19 and the resistor 24 .
  • the discharge circuit 27 described above discharges the capacitor 25 making it possible to control switching means which ensure the opening of the solenoid valve.
  • the switching means are constituted by a relay 41 mounted in series with a diode 42 preventing the excitation of the relay during the charging of the capacitor 25 and authorizing the excitation of the relay during the discharge of the capacitor.
  • the cathode of the diode 42 is connected to the common point, between the capacitor 25 and the anode of the diode 26 , while the relay 41 is connected to the cathode of the diode 26 which is connected to neutral.
  • the contact 41 a associated with the relay 41 , is mounted between the contact 16 and the circuit 1 a for controlling the solenoid valve 4 .
  • the contact 16 closes, making it possible to supply the circuit 14 for producing a low-voltage supply and activating a solenoid valve 45 mounted on the fuel line upstream of the solenoid valve 4 and whose function will appear more clearly in the following description.
  • the charging current supplied by the low voltage positive power supply, flows through the resistor 24 , the capacitor 25 and the diode 26 .
  • the capacitor 25 therefore charges, as illustrated by part C of the curve in FIG. 3. No current flows in the discharge circuit 27 , as long as the voltage drawn by the resistor 37 remains below the threshold voltage of the Zener diode, for example, of the order of 40 volts.
  • a negative voltage therefore appears on the negative armature of the capacitor 25 , so that the diode 42 is polarized in the passing direction, making it possible to ensure the circulation of a discharge current through a mesh formed by the resistor 33 , the transistors 32 , 31 , the coil 41 , the diode 42 and the capacitor 25 .
  • the excitation of the coil 41 causes the passage of the associated contact 41 a , from its rest position to that of work for which the coil 8 of the solenoid valve 4 is excited so as to ensure the opening of the solenoid valve.
  • the flow of current in the mesh thus formed decreases, exponentially, with a determined time constant, so that the discharge voltage corresponds to the shape of the portion D of the curve of FIG. 3 .
  • the excitation time of the relay 41 which is easily adjustable and determined, in relation to the time constant of the discharge of the capacitor, is chosen to correspond to the ignition time Ta of the burner.
  • the safety device therefore allows the opening of the solenoid valve 4 for a determined ignition time and in complete safety, each time the burner is lit, insofar as if a component of the device is defective, the charge of the capacitor 25 can in no case intervene and authorize the opening of the solenoid valve.
  • the safety device according to the invention is capable of providing an additional function which is that of blocking the action of the thermocouple, as soon as an operation stop of the burner occurs.
  • This final discharge value corresponds to a state of equilibrium which is reached when the voltage across the terminals of capacitor 25 becomes equal to the voltage determined by the divider bridge formed by resistors 24 and 33 on the low voltage supply voltage. This voltage is maintained, except for leaks, until the appearance of an order to extinguish the burner.
  • This extinction order which is manifested by the opening of the contact 16 , causes rapid de-energization of the relay 48 , so that the contacts 48 a , 48 b switch to open the thermocouple circuit 11 and ensure the de-energization of the coil 9 to close the solenoid valve 4 .
  • thermocouple makes it possible to block the action of the thermocouple as soon as a burner operation stops, while ensuring that the solenoid valve operates each time the burner is started.
  • Direct blocking of the thermocouple allows the removal of the upstream solenoid valve necessary to shut off the fuel supply as soon as a burner shutdown order occurs.
  • the security device according to the invention makes it possible to ensure two essential security functions by implementing technical means at a reduced cost.
  • the embodiments described are given by way of example.
  • the operation given above remains identical in the case where the low voltage supply voltage is negative.
  • the mounting of the polarized components should be reversed.
  • Fig. 4 illustrates another alternative embodiment making it possible to inhibit the action of the thermocouple as soon as a burner operation stop occurs.
  • the associated contacts 48 a , 48 b are mounted on either side of the capacitor 25 , making it possible to connect the capacitor 25 , either to the circuit 14 for producing a low voltage supply, or to the terminals of the thermocouple circuit.
  • one of the terminals of the thermocouple 11 is connected to the contact 48 b , while the other terminal of the thermocouple 11 is connected, via a resistor 51 , to the contact 48 a .
  • the coil 9 is connected to the two terminals of the thermocouple 11 .
  • relay 48 is energized, so that contacts 48 a , 48 b pass from the position of connection with the thermocouple 11 to that of connection with the circuit 14 , which ensures the charge of the capacitor 25 as explained above.
  • the relay 48 is de-energized, so that the contacts 48 a , 48 b switch to connect the plates of the capacitor 25 to the terminals of the thermocouple 11 , as illustrated in FIG . 4 .
  • the capacitor 25 discharges in the thermocouple 11 and in the resistor 51 connected in series in the thermocouple circuit, to control the discharge current in the thermocouple circuit.
  • Such a discharge produces a circulation of a current opposite to that generated by the rise in temperature, making it possible to ensure the cancellation of the current circulating in the thermocouple 11 and, consequently, in the coil 9 , in order to obtain its de-excitation and the closing of the solenoid valve 4 .
  • an embodiment of the rocker 28 appears.
  • the resistor 33 which is connected to the cathode of the Zener diode 29 , attacks the anode of a thyristor 52 whose cathode is connected to the common point between the resistor 31 , the capacitor 35 and the neutral.
  • the gate of the thyristor 52 is connected to the common point between the capacitor 35 , the resistor 31 and the anode of the Zener diode 29 .
  • the thyristor 52 is triggered when the charging voltage of the capacitor 25 reaches the threshold voltage of the Zener diode 29 .

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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)

Description

La présente invention concerne les moyens techniques mis en oeuvre pour commander l'alimentation en combustile gazeux d'un brûleur au sens général, de caractère domestique ou industriel et susceptible d'équiper tous les appareils ou les installations pour lesquels ils constituent une source de production de chaleur.The present invention relates to the technical means used to control the supply of gaseous fuel to a burner in the general sense, of a domestic or industrial character and capable of equipping all the devices or installations for which they constitute a source of production. heat.

L'invention concerne, plus précisément, les dispositifs adaptés pour assumer une fonction de sécurité lors de l'allumage du brûleur, d'une part, et lors de l'extinction du brûleur, d'autre part.The invention relates, more specifically, to devices adapted to assume a safety function when the burner is lit, on the one hand, and when the burner is turned off, on the other hand.

L'art antérieur a proposé, et notamment par le brevet FR 76-36 750 et la demande de brevet GB-2 196 500, des dispositifs d'allumage de sécurité pour un brûleur. De façon classique, il doit être considéré qu'un brûleur est équipé d'une électrovanne interposée sur la canalisation d'alimentation du brûleur en combustible gazeux. L'électrovanne est pilotée, par l'intermédiaire d'un dispositif de commande temporisée, tel qu'un contacteur asservi à un thermostat ou une horloge de commande. Ce dispositif de commande temporisée permet l'alimentation en combustible du brûleur pendant un temps d'allumage déterminé, de l'ordre d'une quinzaine de secondes. Au-delà de ce temps d'allumage, l'alimentation du brûleur en combustible est conditionnée à la présence effective de la flamme de combustion, détectée par exemple, par l'intermédiaire d'un thermocouple. En effet, pendant le temps d'allumage, la température du thermocouple s'élève en présence d'une flamme, de manière que le thermocouple produise un courant d'excitation d'une bobine adaptée pour maintenir l'électrovanne en position d'ouverture. Si aucune flamme n'apparaît, l'électrovanne d'alimentation est fermée au terme du temps d'allumage, dans la mesure où le thermocouple ne produit aucun courant de maintien de la bobine.The prior art has proposed, and in particular by patent FR 76-36,750 and patent application GB- 2,196,500, safety ignition devices for a burner. Conventionally, it must be considered that a burner is equipped with a solenoid valve interposed on the supply pipe of the burner with gaseous fuel. The solenoid valve is controlled by means of a timed control device, such as a contactor controlled by a thermostat or a control clock. This timed control device allows the fuel supply to the burner for a determined ignition time, of the order of fifteen seconds. Beyond this ignition time, the supply of fuel to the burner is conditioned on the actual presence of the combustion flame, detected for example, by means of a thermocouple. In fact, during the ignition time, the temperature of the thermocouple rises in the presence of a flame, so that the thermocouple produces an excitation current from a coil adapted to maintain the solenoid valve in the open position. . If no flame appears, the supply solenoid valve is closed at the end of the ignition time, insofar as the thermocouple produces no holding current of the coil.

Il apparaît que les dispositifs actuellement connus, de commande temporisée de l'électrovanne, ne sont pas en mesure d'assurer une fonction de sécurité effective du fonctionnement du brûleur. En effet, si un défaut intervient sur l'un des composants constitutif d'un tel dispositif, l'électrovanne peut être maintenue en position d'ouverture avec des conséquences graves, si le combustible n'est pas enflammé, ou être détruite, en raison de la circulation prolongée du courant dans la bobine de maintien de l'électrovanne.It appears that the currently known devices for timed control of the solenoid valve are not able to provide an effective safety function for the operation of the burner. Indeed, if a fault occurs on one of the components constituting such a device, the solenoid valve can be kept in the open position with serious consequences, if the fuel is not ignited, or be destroyed, due to the prolonged flow of current in the holding coil of the solenoid valve.

Par ailleurs, il doit être remarqué que le thermocouple, malgré l'absence de flamme, peut continuer à assurer l'ouverture de l'électrovanne, pendant le temps nécessaire à son refroidissement. Un tel inconvénient du fonctionnement de l'organe de sécurité apparaît, notamment, lors d'un démarrage à chaud du brûleur au-delà de la temporisation d'allumage et à chaque arrêt de fonctionnement du brûleur.Furthermore, it should be noted that the thermocouple, despite the absence of flame, can continue to ensure the opening of the solenoid valve, for the time necessary for its cooling. Such a drawback of the operation of the safety device appears, in particular, during a hot start of the burner beyond the ignition delay and at each stop of operation of the burner.

La présente invention vise donc à remédier aux inconvénients énoncés ci-dessus en proposant un dispositif de sécurité apte à assurer, en toute sécurité, le fonctionnement de l'électrovanne à chaque démarrage, tout en permettant de bloquer l'action du thermocouple dès qu'un arrêt de fonctionnement du brûleur intervient.The present invention therefore aims to remedy the drawbacks stated above by proposing a safety device capable of ensuring, in complete safety, the operation of the solenoid valve at each start-up, while making it possible to block the action of the thermocouple as soon as a burner operation stop occurs.

L'invention vise aussi à ofrir un dispositif adapté pour assurer une fonction effective de sécurité du fonctionnement du brûleur, quel que soit le défaut intervenant sur un composant constitutif du dispositif conforme à l'invention.The invention also aims to provide a device suitable for ensuring an effective safety function of the operation of the burner, whatever the fault occurring on a component of the device according to the invention.

L'invention vise, également, à offrir un dispositif de sécurité de mise en oeuvre simple et présentant un coût de fabrication réduit.The invention also aims to offer a safety device that is simple to use and has a reduced manufacturing cost.

Pour atteindre les buts énoncés ci-dessus, le dispositif de sécurité pour le fonctionnement d'un brûleur à combustible gazeux comportant un système de commande temporisée comprend :

  • un circuit de production d'une alimentation basse tension continue,
  • un condensateur destiné à être alimenté par le circuit lors de l'apparition d'un ordre de commande,
  • et un circuit de décharge du condensateur lorsque la tension de charge du condensateur atteint une tension de seuil fixée par un moyen, de manière que le temps de décharge corresponde au moins à la durée d'allumage du brûleur, la décharge du condensateur permettant de piloter des moyens de commutation assurant l'ouverture d'une électrovanne permettant d'alimenter en combustible le brûleur.
To achieve the goals set out above, the safety device for the operation of a gaseous fuel burner comprising a timed control system comprises:
  • a circuit for producing a low-voltage DC power supply,
  • a capacitor intended to be supplied by the circuit when a control command appears,
  • and a discharge circuit of the capacitor when the charge voltage of the capacitor reaches a threshold voltage fixed by means, so that the discharge time corresponds at least to the duration of ignition of the burner, the discharge of the capacitor making it possible to control switching means ensuring the opening of a solenoid valve making it possible to supply fuel to the burner.

Selon l'invention, les moyens de commutation comportent un relais monté en série avec le condensateur, par l'intermédiaire d'une diode montée pour interdire l'excitation du relais pendant la charge du condensateur et pour autoriser l'excitation du relais lors de la décharge du condensateur, et le dispositif comporte un relais alimenté par le circuit et dont les deux contacts sont montés aux bornes d'un thermocouple, de manière à fermer le circuit thermocouple dès qu'un ordre d'allumage intervient et à inhiber le fonctionnement du thermocouple dès qu'un ordre d'extinction du brûleur intervient.According to the invention, the switching means comprise a relay mounted in series with the capacitor, by means of a diode mounted to prevent excitation of the relay during charging of the capacitor and to authorize excitation of the relay during discharging the capacitor, and the device comprises a relay supplied by the circuit and the two contacts of which are mounted on the terminals of a thermocouple, so as to close the thermocouple circuit as soon as an ignition order intervenes and to inhibit operation of the thermocouple as soon as a burner shutdown order occurs.

Diverses autres caractéristiques ressortent de la description faite ci-dessous en référence aux dessins annexés qui montrent, à titre d'exemples non limitatifs, des formes de réalisation de l'objet de l'invention.Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments of the subject of the invention.

La fig. 1 illustre un exemple d'application du dispositif de sécurité selon l'invention. Fig. 1 illustrates an example of application of the security device according to the invention.

La fig. 2 illustre une variante de réalisation d'un dispositif de sécurité conforme à l'invention assurant une temporisation de l'allumage. Fig. 2 illustrates an alternative embodiment of a safety device according to the invention ensuring an ignition delay.

La fig. 3 est une courbe de tension en fonction du temps, permettant d'expliciter le fonctionnement du dispositif selon l'invention. Fig. 3 is a voltage curve as a function of time, making it possible to explain the operation of the device according to the invention.

La fig. 4 illustre une autre variante de réalisation du dispositif de sécurité selon l'invention. Fig. 4 illustrates another alternative embodiment of the security device according to the invention.

La fig. 1 illustre, à titre d'exemple, une installation comportant un système 1 de sécurité pour le fonctionnement d'un brûleur 2, constituant, dans l'exemple illustré, un brûleur d'un four. Le brûleur 2 est susceptible d'être alimenté en combustible gazeux par l'intermédiaire d'une conduite 3 sur laquelle est montée une électrovanne 4 qui est pilotée par le système 1. L'électrovanne 4, représentée de façon schématique, comporte, de façon classique, un obturateur 5 destiné à être déplacé de son siège 6, par l'intermédiaire d'une tige 7 associée à une bobine d'excitation 8, permettant d'assurer l'alimentation du brûleur en combustible. L'obturateur 5 est associé à une bobine d'excitation 9, adaptée pour maintenir l'obturateur 5 en position d'ouverture. Cette bobine 9 est commandée, par l'intermédiaire d'un moyen 11 de détection de présence d'une flamme, formé, avantageusement, par un thermocouple engendrant un courant d'excitation de la bobine lorsque la température du thermocouple s'est élevée à une température donnée. Le brûleur 2 est pourvu, de façon classique, d'une électrode d'allumage 12 permettant d'enflammer le combustible à l'aide d'étincelles à haute tension générées et commandées par un moyen adapté qui se trouve intégré, dans l'exemple illustré, dans le système de sécurité 1. Fig. 1 illustrates, by way of example, an installation comprising a safety system 1 for the operation of a burner 2 , constituting, in the example illustrated, a burner of an oven. The burner 2 is capable of being supplied with gaseous fuel via a line 3 on which is mounted a solenoid valve 4 which is controlled by the system 1 . The solenoid valve 4 , represented schematically, comprises, in a conventional manner, a shutter 5 intended to be moved from its seat 6 , by means of a rod 7 associated with an excitation coil 8 , making it possible to supply the burner with fuel. The shutter 5 is associated with an excitation coil 9 , adapted to maintain the shutter 5 in the open position. This coil 9 is controlled, by means of a means 11 for detecting the presence of a flame, advantageously formed by a thermocouple generating an excitation current of the coil when the temperature of the thermocouple has risen to a given temperature. The burner 2 is provided, in a conventional manner, with an ignition electrode 12 making it possible to ignite the fuel using high-voltage sparks generated and controlled by a suitable means which is integrated, in the example illustrated, in security system 1 .

Tel que cela ressort plus précisément de la fig. 2, le système de sécurité 1, qui comporte un circuit 1a adapté pour le contrôle de l'électrovanne 4 et de l'électrode d'allumage 12, comprend, conformément à l'invention, un système de commande temporisée 1b adapté pour permettre, à la suite d'un signal de commande du fonctionnement du brûleur, l'ouverture de l'électrovanne pendant une durée d'allumage Ta déterminée, par exemple de l'ordre d'une quinzaine de secondes.As shown more precisely in FIG. 2 , the safety system 1 , which comprises a circuit 1 a suitable for controlling the solenoid valve 4 and the ignition electrode 12 , comprises, in accordance with the invention, a timed control system 1 b adapted for allow, following a command signal from the burner operation, the opening of the solenoid valve during a determined ignition time Ta , for example of the order of fifteen seconds.

Le système de commande temporisée 1b selon l'invention comporte un circuit 14 de production d'une alimentation basse tension continue, à partir d'un réseau d'alimentation. Dans l'exemple illustré, le réseau d'alimentation est du type monophasé et délivre une tension alternative de l'ordre de 220 volts, à travers une ligne de phase L₁ et une ligne neutre L₂.The timed control system 1b according to the invention comprises a circuit 14 for producing a low-voltage DC power supply, from a supply network. In the example illustrated, the supply network is of the single-phase type and delivers an alternating voltage of the order of 220 volts, through a phase line L₁ and a neutral line L₂ .

La ligne de phase L₁ est munie d'un contact 16 d'un thermostat qui permet de donner l'ordre assurant la commande de fonctionnement du brûleur. La ligne L₁ comporte aussi, entre le contact 16 et le circuit 14, un ensemble formé par un condensateur 17 monté en série avec une résistance 18.The phase line L₁ is provided with a contact 16 of a thermostat which makes it possible to give the order ensuring the operation control of the burner. Line L₁ also comprises, between contact 16 and circuit 14 , an assembly formed by a capacitor 17 connected in series with a resistor 18 .

Le circuit 14, qui constitue un redresseur, délivre, dans l'exemple illustré, une tension correspondant aux alternances positives de la tension d'alimentation produite par le réseau. Le circuit 14 est formé par une première diode 19 dont l'anode est reliée au condensateur 17 et à la cathode d'une seconde diode 21. La cathode de la diode 19 est reliée, par l'intermédiaire d'un condensateur 22, au neutre. Un relais 48 est monté entre l'anode de la diode 21 et le point commun entre le neutre et le condensateur 22. Le relais 48, qui est connecté en parallèle avec un condensateur 49, comporte deux contacts associés 48a , 48b montés dans le circuit du thermocouple 11, en parallèle l'un par rapport à l'autre. L'une des bornes du thermocouple 11 est reliée, par l'intermédiaire de la bobine 9, à un point commun des deux contacts, tandis que l'autre borne du thermocouple est connectée à l'autre point commun des contacts.The circuit 14 , which constitutes a rectifier, delivers, in the example illustrated, a voltage corresponding to the half-waves positive of the supply voltage produced by the network. The circuit 14 is formed by a first diode 19 , the anode of which is connected to the capacitor 17 and to the cathode of a second diode 21 . The cathode of the diode 19 is connected, via a capacitor 22 , to the neutral. A relay 48 is mounted between the anode of the diode 21 and the common point between the neutral and the capacitor 22 . The relay 48 , which is connected in parallel with a capacitor 49 , comprises two associated contacts 48 a , 48 b mounted in the circuit of the thermocouple 11 , in parallel with one another. One of the terminals of the thermocouple 11 is connected, via the coil 9 , to a common point of the two contacts, while the other terminal of the thermocouple is connected to the other common point of the contacts.

Le circuit 14 est destiné à alimenter ou charger, à travers une résistance 24 reliée à la cathode de la diode 19, un condensateur 25 qui est connecté au neutre à l'aide d'une diode 26 montée selon son sens direct. Le condensateur 25 est associé à un circuit 27 assurant, lorsque la tension de charge du condensateur 25 atteint une tension de seuil fixée par le circuit 27, la décharge du condensateur 25 jusqu'à une valeur donnée, de manière que le temps de décharge du condensateur corresponde à la durée d'allumage Ta . Un tel circuit de décharge commandée à tension de seuil 27 comporte une bascule 28 montée en parallèle sur le condensateur 25 et un moyen à tension de seuil 29 assurant le déclenchement de la bascule lorsque la tension de charge du condensateur 25 atteint la tension de seuil fixée par le moyen 29 qui est constitué, dans l'exemple illustré, par une diode Zener.The circuit 14 is intended to supply or charge, through a resistor 24 connected to the cathode of the diode 19 , a capacitor 25 which is connected to the neutral using a diode 26 mounted in its direct direction. The capacitor 25 is associated with a circuit 27 ensuring, when the charging voltage of the capacitor 25 reaches a threshold voltage fixed by the circuit 27 , the discharge of the capacitor 25 to a given value, so that the discharge time of the capacitor corresponds to the ignition duration Ta . Such a discharge circuit controlled at threshold voltage 27 comprises a flip-flop 28 mounted in parallel on the capacitor 25 and a threshold-voltage means 29 ensuring the triggering of the flip-flop when the charge voltage of the capacitor 25 reaches the fixed threshold voltage by means 29 which is constituted, in the example illustrated, by a Zener diode.

Dans un premier exemple de réalisation, la bascule 28 est constituée par un premier 31 et un second 32 transistors à couplage direct. L'émetteur du premier transistor 31 est relié, par l'intermédiaire d'une résistance 33, au point commun entre la résistance 24 et le condensateur 25. Le collecteur du transistor 31 attaque la base du second transistor 32 qui comporte, entre sa base et son émetteur, un ensemble formé d'une capacité 35 montée en parallèle avec une résistance 36. L'émetteur du transistor 32, qui est relié au neutre, est connecté à l'anode de la diode Zener 29, tandis que le collecteur du transistor 32 attaque la base du transistor 31 et se trouve relié, d'une part, à la cathode de la diode Zener 29 et, d'autre part, par l'intermédiaire d'une résistance 37, au point commun entre le condensateur 22, la diode 19 et la résistance 24.In a first embodiment, the flip-flop 28 consists of a first 31 and a second 32 direct-coupled transistors. The emitter of the first transistor 31 is connected, via a resistor 33 , to the common point between the resistor 24 and the capacitor 25 . The collector of transistor 31 drives the base of the second transistor 32 which comprises, between its base and its emitter, an assembly formed by a capacitor 35 mounted in parallel with a resistor 36 . The emitter of transistor 32 , which is connected to neutral, is connected to the anode of Zener diode 29 , while the collector of transistor 32 drives the base of transistor 31 and is connected, on the one hand, to the cathode of Zener diode 29 and, on the other hand, via a resistor 37 , at the point in common between the capacitor 22 , the diode 19 and the resistor 24 .

Le circuit de décharge 27 décrit ci-dessus assure la décharge du condensateur 25 permettant de piloter des moyens de commutation qui assurent l'ouverture de l'électrovanne. Avantageusement, les moyens de commutation sont constitués par un relais 41 monté en série avec une diode 42 interdisant l'excitation du relais pendant la charge du condensateur 25 et autorisant l'excitation du relais pendant la décharge du condensateur. A cet effet, dans l'exemple illustré, la cathode de la diode 42 est reliée au point commun, entre le condensateur 25 et l'anode de la diode 26, tandis que le relais 41 est connecté à la cathode de la diode 26 qui est reliée au neutre. Le contact 41a , associé au relais 41, est monté entre le contact 16 et le circuit 1a de contrôle de l'électrovanne 4.The discharge circuit 27 described above discharges the capacitor 25 making it possible to control switching means which ensure the opening of the solenoid valve. Advantageously, the switching means are constituted by a relay 41 mounted in series with a diode 42 preventing the excitation of the relay during the charging of the capacitor 25 and authorizing the excitation of the relay during the discharge of the capacitor. To this end, in the example illustrated, the cathode of the diode 42 is connected to the common point, between the capacitor 25 and the anode of the diode 26 , while the relay 41 is connected to the cathode of the diode 26 which is connected to neutral. The contact 41 a , associated with the relay 41 , is mounted between the contact 16 and the circuit 1 a for controlling the solenoid valve 4 .

Le fonctionnement du dispositif de sécurité selon l'invention découle directement de la description qui précède.The operation of the safety device according to the invention follows directly from the above description.

Lorsque le thermostat donne un ordre de commande du fonctionnement du brûleur, le contact 16 se ferme, permettant d'alimenter le circuit 14 de production d'une alimentation de basse tension et d'activer une électrovanne 45 montée sur la canalisation du combustible en amont de l'électrovanne 4 et dont la fonction apparaîtra plus clairement dans la suite de la description. Le courant de charge, fourni par l'alimentation positive basse tension, circule à travers la résistance 24, le condensateur 25 et la diode 26. Le condensateur 25 se charge donc, comme illustré par la partie C de la courbe de la fig. 3. Aucun courant ne circule dans le circuit de décharge 27, tant que la tension prélevée par la résistance 37 reste inférieure à la tension de seuil de la diode Zener, par exemple, de l'ordre de 40 volts. Lorsque la tension de charge du condensateur 25, prise entre l'armature positive et le neutre, atteint une tension d'avalanche Va égale à la somme de la tension de seuil de la diode Zener et de la tension base-émetteur du transistor 31, un courant apparaît sur la base du transistor 31. Ce courant de base produit, dans le collecteur du transistor 31, un courant qui attaque la base du transistor 32. Un tel courant de base permet d'engendrer, dans le collecteur du transistor 32, un courant qui attaque la base du transistor 31, de sorte qu'apparaît un effet d'avalanche permettant de maintenir les transistors en état de saturation. Par suite, l'armature positive du condensateur 25 est ramenée au potentiel du neutre, par l'intermédiaire de la résistance 33. Une tension négative apparaît donc sur l'armature négative du condensateur 25, de sorte que la diode 42 se trouve polarisée dans le sens passant, permettant d'assurer la circulation d'un courant de décharge à travers une maille constituée par la résistance 33, les transistors 32, 31, la bobine 41, la diode 42 et le condensateur 25. L'excitation de la bobine 41, par un tel courant de décharge, provoque le passage du contact associé 41a , de sa position de repos à celle de travail pour laquelle la bobine 8 de l'électrovanne 4 est excitée de manière à assurer l'ouverture de l'électrovanne.When the thermostat gives a command to control the operation of the burner, the contact 16 closes, making it possible to supply the circuit 14 for producing a low-voltage supply and activating a solenoid valve 45 mounted on the fuel line upstream of the solenoid valve 4 and whose function will appear more clearly in the following description. The charging current, supplied by the low voltage positive power supply, flows through the resistor 24 , the capacitor 25 and the diode 26 . The capacitor 25 therefore charges, as illustrated by part C of the curve in FIG. 3. No current flows in the discharge circuit 27 , as long as the voltage drawn by the resistor 37 remains below the threshold voltage of the Zener diode, for example, of the order of 40 volts. When the charging voltage of capacitor 25 , taken between the armature positive and neutral, reaches an avalanche voltage Va equal to the sum of the threshold voltage of the Zener diode and the base-emitter voltage of transistor 31 , a current appears on the base of transistor 31 . This base current produces, in the collector of transistor 31 , a current which attacks the base of transistor 32 . Such a base current makes it possible to generate, in the collector of the transistor 32 , a current which attacks the base of the transistor 31 , so that an avalanche effect appears allowing the transistors to be kept in a saturation state. As a result, the positive armature of the capacitor 25 is brought back to the neutral potential, via the resistor 33 . A negative voltage therefore appears on the negative armature of the capacitor 25 , so that the diode 42 is polarized in the passing direction, making it possible to ensure the circulation of a discharge current through a mesh formed by the resistor 33 , the transistors 32 , 31 , the coil 41 , the diode 42 and the capacitor 25 . The excitation of the coil 41 , by such a discharge current, causes the passage of the associated contact 41 a , from its rest position to that of work for which the coil 8 of the solenoid valve 4 is excited so as to ensure the opening of the solenoid valve.

La circulation du courant dans la maille ainsi formée décroit, de façon exponentielle, avec une constante de temps déterminée, de sorte que la tension de décharge correspond à l'allure de la portion D de la courbe de la fig. 3. Lorsque la tension aux bornes du relais 41 atteint la tension V r de désexcitaton du relais, ce dernier passe en position de repos, de sorte que la bobine 8 ne se trouve plus alimentée. Avantageusement, le temps d'excitation du relais 41, qui est facilement réglable et déterminée, en relation de la constante de temps de la décharge du condensateur, est choisi pour correspondre au temps d'allumage Ta du brûleur. Ainsi, si pendant le temps d'allumage la température du thermocouple s'est élevée en présence d'une flamme, le thermocouple engendre un courant d'excitation de la bobine 9 permettant de maintenir ouverte l'électrovanne 4. Si tel n'est pas le cas, l'électrovanne 4 est fermée au terme du temps, d'allumage Ta .The flow of current in the mesh thus formed decreases, exponentially, with a determined time constant, so that the discharge voltage corresponds to the shape of the portion D of the curve of FIG. 3 . When the voltage at the terminals of relay 41 reaches the de-energizing voltage V r of the relay, the latter goes into the rest position, so that the coil 8 is no longer supplied. Advantageously, the excitation time of the relay 41 , which is easily adjustable and determined, in relation to the time constant of the discharge of the capacitor, is chosen to correspond to the ignition time Ta of the burner. Thus, if during the ignition time the temperature of the thermocouple has risen in the presence of a flame, the thermocouple generates an excitation current from the coil 9 allowing the solenoid valve 4 to be kept open. If this is not the case, the solenoid valve 4 is closed at the end of the time, ignition Ta .

Le dispositif de sécurité selon l'invention permet donc l'ouverture de l'électrovanne 4 pendant un temps d'allumage déterminé et en toute sécurité, à chaque allumage du brûleur, dans la mesure où si un composant du dispositif est défectueux, la charge du condensateur 25 ne peut, en aucun cas, intervenir et autoriser l'ouverture de l'électrovanne.The safety device according to the invention therefore allows the opening of the solenoid valve 4 for a determined ignition time and in complete safety, each time the burner is lit, insofar as if a component of the device is defective, the charge of the capacitor 25 can in no case intervene and authorize the opening of the solenoid valve.

Par ailleurs, le dispositif de sécurité selon l'invention est apte à assurer une fonction supplémentaire qui est celle de bloquer l'action du thermocouple, dès qu'un arrêt de fonctionnement du brûleur intervient.Furthermore, the safety device according to the invention is capable of providing an additional function which is that of blocking the action of the thermocouple, as soon as an operation stop of the burner occurs.

Ainsi, lorsqu'un ordre de fonctionnement du brûleur apparaît, un courant traverse la diode 21, le relais 48 et le condensateur 49, pendant les alternances négatives de l'alimentation, de sorte qu'une tension continue positive est présente aux bornes du relais 48 dont les contacts passent de la position de liaison à un point neutre ou en l'air à celle de connexion avec le thermocouple 11. Après la charge du condensateur 25 selon le principe décrit ci-dessus, ce dernier se décharge jusqu'à une valeur donnée V D égale ou inférieure à la tension de désexcitation du relais 41, de manière à autoriser, au terme d'un délai correspondant au temps d'allumage, l'arrêt de la commande de la bobine 8 de l'électrovanne. Cette valeur finale de décharge correspond à un état d'équilibre qui est atteinte lorsque la tension aux bornes du condensateur 25 devient égale à la tension déterminée par le pont diviseur formé par les résistances 24 et 33 sur la tension d'alimentation basse tension. Cette tension est maintenue, aux fuites près, jusqu'à l'apparition d'un ordre d'extinction du brûleur. Cet ordre d'extinction, qui se manifeste par l'ouverture du contact 16, provoque une désexcitation rapide du relais 48, de sorte que les contacts 48a , 48b commutent pour ouvrir le circuit thermocouple 11 et assurer la désexcitation de la bobine 9 en vue de fermer l'électrovanne 4.Thus, when an operating order of the burner appears, a current flows through the diode 21 , the relay 48 and the capacitor 49 , during the negative half-waves of the supply, so that a positive DC voltage is present at the terminals of the relay. 48 , the contacts of which pass from the position of connection to a neutral point or in the air to that of connection with the thermocouple 11 . After charging the capacitor 25 according to the principle described above, the latter discharges up to a given value V D equal to or less than the de-excitation voltage of the relay 41 , so as to authorize, at the end of a corresponding delay at ignition time, stopping the control of the coil 8 of the solenoid valve. This final discharge value corresponds to a state of equilibrium which is reached when the voltage across the terminals of capacitor 25 becomes equal to the voltage determined by the divider bridge formed by resistors 24 and 33 on the low voltage supply voltage. This voltage is maintained, except for leaks, until the appearance of an order to extinguish the burner. This extinction order, which is manifested by the opening of the contact 16 , causes rapid de-energization of the relay 48 , so that the contacts 48 a , 48 b switch to open the thermocouple circuit 11 and ensure the de-energization of the coil 9 to close the solenoid valve 4 .

Il apparaît donc que le dispositif de sécurité selon l'invention permet de bloquer l'action du thermocouple dès qu'un arrêt de fonctionnement du brûleur intervient, tout en assurant le fonctionnement de l'électrovanne à chaque démarrage du brûleur. Le blocage direct du thermocouple autorise la suppression de l'électrovanne amont nécessaire pour fermer l'alimentation en combustible dès qu'un ordre arrêt du brûleur intervient.It therefore appears that the safety device according to the invention makes it possible to block the action of the thermocouple as soon as a burner operation stops, while ensuring that the solenoid valve operates each time the burner is started. Direct blocking of the thermocouple allows the removal of the upstream solenoid valve necessary to shut off the fuel supply as soon as a burner shutdown order occurs.

Il doit être constaté que le dispositif de sécurité selon l'invention permet d'assurer deux fonctions essentielles de sécurité en mettant en oeuvre des moyens techniques d'un coût réduit. Bien entendu, les variantes de réalisation décrites sont données à titre d'exemple. Ainsi, le fonctionnement donné ci-dessus reste identique dans le cas où la tension d'alimentation basse tension est négative. Dans cet exemple, il convient d'inverser le montage des composants polarisés.It should be noted that the security device according to the invention makes it possible to ensure two essential security functions by implementing technical means at a reduced cost. Of course, the embodiments described are given by way of example. Thus, the operation given above remains identical in the case where the low voltage supply voltage is negative. In this example, the mounting of the polarized components should be reversed.

La fig. 4 illustre une autre variante de réalisation permettant d'inhiber l'action du thermocouple dès qu'un arrêt de fonctionnement du brûleur intervient. Selon cette variante, les contacts associés 48a , 48b sont montés de part et d'autre du condensateur 25, permettant de relier le condensateur 25, soit au circuit 14 de production d'une alimentation basse tension, soit aux bornes du circuit thermocouple. A cet effet, l'une des bornes du thermocouple 11 est reliée au contact 48b , tandis que l'autre borne du thermocouple 11 est connectée, par l'intermédiaire d'une résistance 51, au contact 48a . La bobine 9 est reliée aux deux bornes du thermocouple 11. Fig. 4 illustrates another alternative embodiment making it possible to inhibit the action of the thermocouple as soon as a burner operation stop occurs. According to this variant, the associated contacts 48 a , 48 b are mounted on either side of the capacitor 25 , making it possible to connect the capacitor 25 , either to the circuit 14 for producing a low voltage supply, or to the terminals of the thermocouple circuit. . For this purpose, one of the terminals of the thermocouple 11 is connected to the contact 48 b , while the other terminal of the thermocouple 11 is connected, via a resistor 51 , to the contact 48 a . The coil 9 is connected to the two terminals of the thermocouple 11 .

Dès qu'un ordre de fonctionnement du brûleur est donné par le contact 16, le relais 48 est excité, de sorte que les contacts 48a , 48b passent de la position de liaison avec le thermocouple 11 à celle de connexion avec le circuit 14, ce qui permet d'assurer la charge du condensateur 25 comme expliqué ci-avant. Lorsque le contact 16 est ouvert, le relais 48 est désexcité, de sorte que les contacts 48a , 48b commutent pour relier les armatures du condensateur 25 aux bornes du thermocouple 11, comme illustré à la fig. 4. Le condensateur 25 se décharge dans le thermocouple 11 et dans la résistance 51 montée en série dans le circuit thermocouple, pour contrôler le courant de décharge dans le circuit thermocouple. Une telle décharge produit une circulation d'un courant opposé à celui engendré par l'élévation de température, permettant d'assurer l'annulation du courant circulant dans le thermocouple 11 et, par suite, dans la bobine 9, en vue d'obtenir sa désexcitation et la fermeture de l'électrovanne 4.As soon as a burner operating order is given by contact 16 , relay 48 is energized, so that contacts 48 a , 48 b pass from the position of connection with the thermocouple 11 to that of connection with the circuit 14 , which ensures the charge of the capacitor 25 as explained above. When the contact 16 is open, the relay 48 is de-energized, so that the contacts 48 a , 48 b switch to connect the plates of the capacitor 25 to the terminals of the thermocouple 11 , as illustrated in FIG . 4 . The capacitor 25 discharges in the thermocouple 11 and in the resistor 51 connected in series in the thermocouple circuit, to control the discharge current in the thermocouple circuit. Such a discharge produces a circulation of a current opposite to that generated by the rise in temperature, making it possible to ensure the cancellation of the current circulating in the thermocouple 11 and, consequently, in the coil 9 , in order to obtain its de-excitation and the closing of the solenoid valve 4 .

Dans cet exemple, illustré à la fig. 4, il apparaît une forme de réalisation de la bascule 28. La résistance 33, qui se trouve reliée à la cathode de la diode Zener 29, attaque l'anode d'un thyristor 52 dont la cathode est reliée au point commun entre la résistance 31, le condensateur 35 et le neutre. La grille du thyristor 52 est connectée au point commun entre le condensateur 35, la résistance 31 et l'anode de la diode Zener 29. Le thyristor 52 est déclenché lorsque la tension de charge du condensateur 25 atteint la tension de seuil de la diode Zener 29.In this example, illustrated in fig. 4 , an embodiment of the rocker 28 appears. The resistor 33 , which is connected to the cathode of the Zener diode 29 , attacks the anode of a thyristor 52 whose cathode is connected to the common point between the resistor 31 , the capacitor 35 and the neutral. The gate of the thyristor 52 is connected to the common point between the capacitor 35 , the resistor 31 and the anode of the Zener diode 29 . The thyristor 52 is triggered when the charging voltage of the capacitor 25 reaches the threshold voltage of the Zener diode 29 .

Claims (7)

  1. Safety device for the operation of a gas fuel burner (2), including a delayed control system (1b) comprising:
    - a circuit (14) for producing a low-voltage d.c. supply,
    - a capacitor (25) intended to be supplied by the circuit (14) on appearance of a control command,
    - and a circuit (27) for discharging the capacitor (25) when the charging voltage of the capacitor (25) reaches a threshold voltage (Va) which is fixed by a means (29), such that the discharge time corresponds to at least the ignition duration (Ta) of the burner, the discharge of the capacitor making it possible to drive switching means (41, 41a) which open a solenoid valve (4) allowing fuel to be fed to the burner,
       characterized in that the switching means include a first relay (41) mounted in series with the capacitor (25), via a diode (42) mounted to prevent energizing of the relay during the charging of the capacitor and to allow energizing of the relay during the discharge of the capacitor, and in that it comprises a second relay (48) supplied by the circuit (14) for producing a low-voltage d.c. supply, the two contacts (48a, 48b) of which are mounted at the terminals of a thermocouple (11), so as to close the thermocouple circuit as soon as an ignition command intervenes and to disable operation of the thermocouple as soon as a command for extinguishing the burner intervenes.
  2. Device according to Claim 1, characterized in that the two controlled contacts (48a, 48b) are mounted in parallel with respect to each other in the thermocouple circuit and open the thermocouple circuit on emission of an extinguishing command.
  3. Device according to Claim 1, characterized in that the two controlled contacts (48a, 48b) are each connected to one of the plates of the capacitor (25), making it possible to connect the capacitor (25) either to the circuit (14) for producing a low-voltage d.c. supply when a control command for operating the burner appears, or to the terminals of the thermocouple when a command for extinguishing the burner intervenes, so as to inject, into the thermocouple, a current which is sufficient to cancel that flowing with a view to closing the solenoid valve (4) immediately.
  4. Device according to Claim 1, characterized in that the capacitor (25) includes in series a diode (26) placed in parallel on the diode (42) and the relay (41), which makes it possible to charge the capacitor through the circuit (14) for producing a low-voltage d.c. supply.
  5. Device according to Claim 1, characterized in that the discharge circuit (27) includes a flip-flop (28) mounted in parallel on the capacitor (25) and consists of a first (31) and a second (32) complementary direct-coupling transistors, the first transistor (31) being connected, on the one hand, by its emitter and via a resistor (33), to one of the plates of the capacitor (25) and, on the other hand, by its collector, to the base of the second transistor (31) and to a unit formed by a capacitance (35) mounted in parallel on a resistor (32), whilst the second transistor (31) is connected, on the one hand, by its collector, to the base of the first transistor and to the cathode of a Zener diode (29) forming the threshold voltage triggering means and, on the other hand, by its emitter to the anode of the Zener diode (29) and to the resistor (32)/capacitance (35) unit.
  6. Device according to Claim 1, characterized in that the discharge circuit (27) includes a flip-flop (28) consisting of a thyristor (52) whose gate is controlled by the threshold voltage means (29).
  7. Safety device according to Claims 1, 5 and 6, characterized in that the discharge circuit (27) is designed to discharge the capacitor to a given value (VD) equal to or less than the de-energizing voltage (Vr) of the relay (41) of the switching means.
EP91420025A 1990-01-26 1991-01-28 Safety device for the operating of a burner Expired - Lifetime EP0439417B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9001167A FR2657684B1 (en) 1990-01-26 1990-01-26 SAFETY DEVICE FOR THE OPERATION OF A BURNER.
FR9001167 1990-01-26

Publications (2)

Publication Number Publication Date
EP0439417A1 EP0439417A1 (en) 1991-07-31
EP0439417B1 true EP0439417B1 (en) 1994-01-19

Family

ID=9393299

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91420025A Expired - Lifetime EP0439417B1 (en) 1990-01-26 1991-01-28 Safety device for the operating of a burner

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Country Link
EP (1) EP0439417B1 (en)
FR (1) FR2657684B1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9021214D0 (en) * 1990-09-28 1990-11-14 Black Automatic Controls Limit Control circuit
EP0837283B1 (en) 1996-10-16 1999-12-22 Sit la Precisa S.p.a. An automatic control system with double safety protection for intermittently-operated gas burners
ES2238905B1 (en) * 2003-07-09 2006-12-01 Orkli, S. Coop. "SUPPLY CIRCUIT OF A SAFETY VALVE FOR THE IGNITION OF A GAS BURNER".
ATE404824T1 (en) * 2005-06-30 2008-08-15 Orkli S Coop Ltda GAS BURNER WITH POWER SUPPLY CIRCUIT OF A SAFETY VALVE FOR THE IGNITION PROCESS OF THE GAS BURNER
CN103244973A (en) * 2013-05-08 2013-08-14 刘敏 Novel electronic gas stove switch timer and timing flameout method of electronic timer

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720858A (en) * 1971-07-20 1973-03-13 Columbia Gas Syst Service Corp Relay timing system
FR2560357B1 (en) * 1984-02-27 1989-04-28 Vano Sa Prod CONTROL SYSTEM FOR THE GAS BURNER OF AN APPLIANCE AND APPARATUS PROVIDED WITH SUCH AN INSTALLATION
JPS60147055A (en) * 1984-03-16 1985-08-02 Rinnai Corp Push-button operating device of water heater
JPS61125521A (en) * 1984-11-21 1986-06-13 Rinnai Corp Control unit of burner
GB8620960D0 (en) * 1986-08-29 1986-10-08 Baxi Partnership Ltd Control circuit

Also Published As

Publication number Publication date
FR2657684A1 (en) 1991-08-02
EP0439417A1 (en) 1991-07-31
FR2657684B1 (en) 1995-07-21

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