EP0024231A1 - Control devices for gas valves - Google Patents

Abstract

The improvement comprises controlling the opening of a valve 1 capable of feeding a burner 14 with a fuel gas under pressure, while ensuring that this valve closes again at the end of a time To of the order of 3 seconds, if the gas it has delivered has not ignited in the meantime. The feeding of the valve 1 is provided for exclusively by the discharge of a capacitor 3 which is charged in advance from the mains supply 2, and if the ignition of the gas is detected during the time To, said feeding is taken over directly by said mains supply 2. <IMAGE>

Description

The invention relates to valve control devices intended to supply pressurized combustible gas to the burners of gas appliances such as water heaters, bath heaters and boilers intended for central heating by circulation of hot water. in radiators.

More particularly, it concerns, among these control devices, those for which the valves in question are electrically controlled by a direct voltage, and which comprise: a capacitor having a capacity such that, from its electrically charged state, its discharge in the valve ensures opening thereof for a predetermined period of between 1 and 5 s; a two-position switch mounted in such a way that, for a first position of this switch, the capacitor is charged from a source of electric voltage and that, for the second position of said switch, the capacitor is discharged towards the valve; means slaved to the control of the ignition of the device to control the movements of this switch from its first to its second position at the start of the ignition periods; and means slaved to the effective ignition of the gas delivered by the valve to activate new means of electrical supply to the valve.

The role of these new means is to take over from the initial discharge of the capacitor if, and only if, the fuel delivered by the valve open thanks to this discharge was effectively ignited during said discharge.

In a known embodiment of such a device, the new means in question still involve the capacitor and are arranged so as to subject the latter to an uninterrupted periodic series of recharges by the source and discharges in the valve. . - This solution, which requires an uninterrupted series of openings and closings of electrical circuits enslaved to each other is complicated, expensive and above all its reliability is questionable.

The invention aims, above all, to propose to constitute the new means in question a particularly simple, robust and reliable solution.

It consists in arranging the above new means in such a way that they permanently connect the source to the valve, independently of the capacitor.

In preferred embodiments, the source is a source of alternating electrical voltage and the new means comprise a first unidirectional member interposed between this source and the switch in the direction allowing the charging of the capacitor from the source, a second unidirectional member interposed between the switch and the valve in the direction allowing the discharge of the capacitor in this valve, and a conductive section interposed between a first point located between the source and the first unidirectional member and a second point located between the second unidirectional member and the valve , this section itself comprising, on the one hand, a third unidirectional member mounted in the direction allowing the supply of the valve through it from the source and, on the other hand, an electric switch controlled by the effective gas ignition.

As regards the capacitor, its capacity is relatively high: this is how, if the supply voltage of the device is the AC mains voltage at 220 V and if the electric power consumed by the valve is of the order from 5 to 50 W, the capacity of this capacitor is between 100 and 1000 uF, said capacitor preferably being of an electrochemical type.

The invention includes, apart from these main provisions, certain other provisions which are preferably used at the same time and which will be more - explicitly discussed below.

In what follows, a preferred embodiment of the invention will be described with reference to the attached drawing, of course in a non-limiting manner.

The single figure of this drawing shows, very schematically, a device established according to the invention for controlling the fuel gas supply valve of a central heating boiler with hot water.

The valve in question has been designated by reference 1 on this diagram.

It is a safety valve, which is open only if it is electrically powered, any absence of electrical power resulting in its automatic closing.

• - un condensateur 3 de capacité suffisante pour que sa décharge dans la vanne puisse ouvrir celle-ci pendant une période prédéterminée T₀,
• - un commutateur 4 à deux positions monté de façon à relier le condensateur 3 soit à la source 2, soit à la vanne 1,
• - un premier redresseur 5 interposé entre la source 2 et le commutateur 4 dans le sens permettant la charge de ce condensateur par la source,
• - et un second redresseur 6 interposé entre le commutateur 4 et la vanne 1 dans le sens permettant la décharge du condensateur dans la vanne.

The control device of this valve is supplied from the alternating voltage emitted by a source 2, which is in particular the sector, and it essentially comprises:

• a capacitor 3 of sufficient capacity so that its discharge in the valve can open the latter for a predetermined period T ₀ ,
• a two-position switch 4 mounted so as to connect the capacitor 3 either to the source 2 or to the valve 1,
• a first rectifier 5 interposed between the source 2 and the switch 4 in the direction allowing the charging of this capacitor by the source,
• - And a second rectifier 6 interposed between the switch 4 and the valve 1 in the direction allowing the discharge of the capacitor in the valve.

The capacitor 3 is in particular of the electrochemical type and its capacity depends on the voltages involved and on the electric power consumed by the valve for its opening: in the case where the source 2 is the sector, that is to say a source of alternating voltage at 220 V, if the power in question is of the order of ten W, said capacity is between 300 and 400 µF, but, all things also equal, said capacity would be 100 times higher if the supply voltage had a value 10 times lower.

The period T ₀ is generally between 1 and 5 s and is preferably of the order of 3 seconds.

• - un interrupteur général 7,
• - et une résistance de charge 8 montée entre le redresseur 5 et le commutateur 4.

We can still see on the drawing:

• - a main switch 7,
• - And a load resistor 8 mounted between the rectifier 5 and the switch 4.

We will return later to the other elements shown in the drawing, those which have been described above making it possible to understand the general principle of operation of the device, which is as follows.

At rest, that is to say when the valve 1 is closed and no gas flow is therefore delivered to the device, the switch 4 is in its first position, which has been illustrated in solid lines on the drawing, for which the capacitor 3 is connected to the source 2; if the main switch 7 is closed, this capacitor then charges electrically to the maximum through components 5 and 8.

The ignition control results in the switching of the switch 4 from its above position to its second position, illustrated in dashes: the capacitor 3 is immediately discharged into the valve 1 through the component 6, which opens this valve , and this during period T.

If, during this period T, the electrical supply of the valve 1 is not relayed by other means sensitive to the effective ignition of the pressurized gas delivered by the valve, the latter must close: it is indeed impossible that the capacitor 3 discharges in the valve an electrical energy higher than that which it stored beforehand.

The security of this type of food is therefore absolute, which represents a capital advantage.

In what follows, we will describe the solution adopted according to the invention to take over from the above discharge if, and only if, the combustible gas delivered by the valve 1 has actually ignited during the period T ₀ .

• - un tronçon de fil conducteur 9 relie un premier point M situé entre la source 2 et le redresseur 5 à un second point P situé entre le redresseur 6 et la vanne 1, tronçon comprenant,d'une part, un troisième redresseur 10 monté dans le sens qui permet l'alimentation à travers lui de la vanne 1 à partir de la source 2, et, d'autre part, l'interrupteur 11 d'un relais 12,
• - le basculement du commutateur 4 assure simultanément l'excitation d'un allumeur 13, ce qui a été sym- bolysé par la flèche F,
• - l'allumage effectif, à l'aide de cet allumeur 13, du gaz délivré à travers successivement la vanne 1 et le brûleur 14 de l'appareil, est détecté par un organe 15,
• - et cet organe 15 est associé au relais 12 ci-dessus de façon telle que seule la présence effective d'une flamme se traduise par l'excitation de ce relais et la fermeture de son interrupteur 11, ce qui est schématisé par la flèche G, l'absence de l'extinction de ladite flamme assurant au contraire automatiquement l'ouverture dudit interrupteur 11.

According to this solution,

• a section of conducting wire 9 connects a first point M located between the source 2 and the rectifier 5 to a second point P located between the rectifier 6 and the valve 1, section comprising, on the one hand, a third rectifier 10 mounted in the direction which allows the supply through it of the valve 1 from the source 2, and, on the other hand, the switch 11 of a relay 12,
• the switching of the switch 4 simultaneously excites an igniter 13, which has been symbolized by the arrow F,
• the effective ignition, using this igniter 13, of the gas delivered successively through the valve 1 and the burner 14 of the appliance, is detected by a member 15,
• - And this member 15 is associated with the relay 12 above so that only the effective presence of a flame results in the excitation of this relay and the closing of its switch 11, which is shown schematically by the arrow G , the absence of the extinction of said flame ensuring on the contrary automatically the opening of said switch 11.

The response time of the chain F, 13, 15, G, 11 is less than the period T ₀ , so that, if the gas supplied by the burner 14 is correctly ignited, the electrical supply to the valve 1, initiated by the discharge of the capacitor 3, is relayed by the source 2 through the elements 9, 10, 11 before total exhaustion of the energy discharged by this capacitor.

Of course, if no flame appears at the burner 14 and / or is not detected by the member 15 during said period T ₀ , the switch 11 remains open and, after exhaustion of the capacitor 3 at the end of the period T ₀ , the valve 1 is closed, which requires external intervention; any risk of pollution and / or explosion is therefore ruled out.

The return of the switch 4 to its initial position can be subject to the cessation of the phenomenon to which the triggering of the ignition is subject.

In a particularly interesting application shown diagrammatically in the drawing, the phenomenon in question is the circulation of water in a pipe 16 intended to be heated by the gas of the burner 14, the pipe forming part of a water heater or of a boiler intended for central heating by circulation of water changed in radiators 17 using a pump 18.

In a manner known per se for such an application, a vacuum created by this circulation of water acts on the membrane 19 of a differential valve 20, so as to open a gas valve 21 interposed between the valve 1 and the burner 14, and it is the movements of this gas valve which are used to control, directly or indirectly, the switching of the switch 4: this operation has been shown diagrammatically by the dashed line H in the drawing.

We finally see that with such an installation, the starting of the circulation pump 18, due in particular to the emission of a control signal by a room thermostat, successively causes the circulation of water in the installation, opening of the gas valve 21, switching of the switch 4, supply and opening of the valve 1 by discharging the capacitor 3 therein, and therefore the distribution of pressurized gas by the burner 14, the excitation of the igniter 13, the detection of the resulting flame at 15, the closing of the switch 11, and the taking over of the supply of the valve by the source 2 through the latter.

If no ignition of the gas normally delivered by the open valve 1 is observed for a period T following its opening, the latter closes automatically, as previously indicated.

As a result of which, and whatever the embodiment adopted, a valve control device is finally obtained, the constitution and operation of which result sufficiently from the above.

Such a device has many advantages over those existing to date, in particular with regard to reliability, small size, robustness, simplicity and low price, since most of the constituent elements can be formed from electronic organs.

As goes without saying, and as it already follows from the above, the invention is in no way limited to those of its embodiments and of application which have been more especially envisaged; on the contrary, it embraces all variants, in particular those in which the valve control device described above would equip an appliance other than a water heater, a bath heater, or a circulation boiler. 'water, device in which the valve would still be controlled, not manually, but automatically depending in particular on the exceeding of a given threshold by a predetermined parameter such as time (timer) or temperature (thermostat).

Claims (3)

1.- Device for controlling a valve intended to supply combustible gas to the burner of a gas appliance, comprising: a capacitor having a capacity such that from its electrically charged state, its discharge in the valve ensures opening thereof for a predetermined period of between 1 and 5 s; a two-position switch, mounted in such a way that, for a first arrangement of this switch, the capacitor is charged from an electric voltage source and that, for the second position of said switch, the capacitor is discharged towards the valve ; means slaved to the control of the ignition of the device to control the movements of this switch from its first to its second position at the start of the ignition periods; and means slaved to the effective ignition of the gas delivered by the valve to activate new means of electric supply to this valve, characterized in that the new means are arranged so as to permanently connect the source (2) to the valve (1) independently of the capacitor (3). 2.- control device according to claim 1, characterized in that the source (2) is a source of alternating voltage and in that the new means comprise a first unidirectional member (5) interposed between this source and the switch (4 ) in the direction allowing the charging of the capacitor (3) from the source, a second unidirectional member (6) interposed between the switch and the valve (1) in the direction allowing the discharge of the capacitor in this valve, and a section conductor (9) interposed between a first point (M) located between the source and the first unidirectional member and a second point (P) located between the second unidirectional member and the valve, this section itself comprising, on the one hand, a third unidirectional member (10) mounted in the direction allowing supplying the valve through it from the source and, on the other hand, an electric switch (11) slaved to the effective ignition of the gas. 3.- Control device according to any one of the preceding claims, characterized in that the electric voltage source (2) being the sector (alternating voltage at 220 V) and the electric power consumed by the valve being of the order from 5 to 50 W, the capacitor capacity is between 100 and 1000 microfarads.

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