EP0020280B1 - Fail-safe ignition device for a valve of a burner - Google Patents

Abstract

This safety ignition device intended notably for controlling the valve through which gaseous fuel is supplied to a burner injector comprises essentially built-in means for protecting the circuitry from transient overvoltages and current surges, notably a varistor for limiting peak voltages and currents, absorbing disturbing energies and stabilizing pressures.

Description

The present invention relates to a safety ignition device intended in particular to operate in combination with a valve in particular for burners or radiant panels comprising a valve body having a gas supply duct and a housing for an injector, containing a seat for a valve comprising on the one hand a safety body housing a magnetic head provided with a winding connected by an electrical conductor to a thermocouple and on the other hand a control unit housing a valve control coil, a production assembly of gas ignition sparks, a rectifier, a printed circuit and a grounding lug.

Devices of a similar type are known. For example, in French Patent No. 2,178,756, a device is described comprising two burners, a valve comprising a hollow cylindrical body at the base of which is placed a magnetic head in which a plunger core comprising a rod secured to it can slide. a disk. A valve is crimped thereon and held in the closed position by a spring. The magnetic head is connected to a thermocouple located in the flame of a burner. A magnetic coil allows the opening of the valve while the thermo. couple is sufficiently heated. A printed circuit is connected to a rectifier giving greater stability to the action of the coil.

Neighboring devices are described in US Patent No. 3,191,661 and German Patent No. 1,551,949.

These known devices have certain limitations or drawbacks. Thus, they can be in the first place the cause of parasitic disturbances such as transient overvoltages on the supply line of the normal network which then transmits them to receivers which is troublesome; they generally include scattered electrical and electronic components, unprotected and connected by bulky electrical conductors.

The object of the present invention is in particular to overcome these drawbacks by proposing such an ignition device characterized in that the integrated means of protection against transient overvoltages consist of a "varistor making it possible to limit the voltages and the shock currents , absorb disturbing energies and stabilize tensions.

According to another characteristic of the invention, the means of protection against transient overvoltages, the coil, the rectifier, the igniter of the spark production assembly, the printed circuit and the respective connections are housed in a control in the form of a molded block of insulating, compact, waterproof and protected material.

In such an ignition device, any operational disturbances and possible destruction caused by the existing voltage peaks either due to the supply current or due to a transformer are eliminated and this up to several thousand volts, which greatly improves the reliability of the device.

The presence of a rectifier which can be a diode bridge ensures a power supply which eliminates any vibration and improves the reliability of the assembly.

The electrical part of the device is preferably integrated in a single housing overmolded in resin or other insulating body, and therefore totally waterproof and protected from dust and corrosive atmospheres, compact, less bulky, easier to use, interchangeable.

By using common components for the igniter and the valve remote control, its cost is lowered by improving the reliability and the simultaneity of the ignition and gas supply functions by opening the valve.

The connections of the control unit to the members remaining outside of it are reduced to the maximum, which is also an element of essential improvement in the reliability of the device.

• la figure 1 est une vue schématique partiellement arrachée du dispositif selon l'invention ;
• la figure 2 est une vue schématique du schéma électrique selon une première forme d'exécution de ce dispositif, et,
• la figure 3 est une vue schématique du schéma électrique selon une seconde forme d'exécution du dispositif de l'invention.

Other advantages will also emerge from the description of two preferred but in no way limitative embodiments of the invention and the attached drawing, including:

• Figure 1 is a partially cutaway schematic view of the device according to the invention;
• FIG. 2 is a schematic view of the electrical diagram according to a first embodiment of this device, and,
• Figure 3 is a schematic view of the electrical diagram according to a second embodiment of the device of the invention.

The improved safety ignition device according to the present invention and FIG. 1 is in particular intended to operate in combination with a valve 1, for example for burners or radiant panels, which comprises a rigid valve body 2 provided with a connection d inlet 3 forming a supply duct 4 for combustible gas and an adjacent and opposite housing 5 for an injector 6 not forming part of the invention.

The valve body 2 defines a valve seat 7 for a valve 8 interposed on the passage of gas between the supply duct 4 and the injector 6 capable of allowing or prohibiting the passage of gas from the duct 4 to the injector 6, in the direction of the arrows f.

The valve body 2 also comprises a safety body 9, hollow adjacent to the connector 3 and to the housing 5, in communication with the interior space for the passage of the gas in which is housed a magnetic head 10 maintained for example by means of a gas tight nut screwed onto the safety body which comprises in particular a winding of a fixed electromagnet (not shown), connected by conductors electrical 11 to a thermocouple 12 which, once brought to a certain temperature, causes the circulation of a microcurrent in the winding sufficient to keep the valve 8 away from its seat, by establishing communication between the conduit 4 and the injector 6.

The thermocouple 12 is placed, as necessary, either in the flame of the injector 6, or in the flame of a burner, or in any other place whose temperature is a factor controlling the operation of the injector 6.

The valve body 2 finally comprises a hollow pusher body 13, adjacent to the inlet connector 3 and to the housing 5, in the same direction and in the opposite direction to the safety body 9, to the end part of which is preferably fixed. removable, a control unit 14.

This control unit 14 serves as a housing for a coil 15 having a winding 16 in which is axially sliding mounted a plunger core 17 bearing on a push rod 18 mounted axially sliding in the pusher body by means of guidance and resting at one of its ends on the plunger core 17 and, at its other end, on the valve 8, on the side opposite to that where its rod is located.

When the winding 16 of the coil 15 is traversed by a current, the plunger core 17 is moved upwards on the left half-view of FIG. 1 by driving, thanks to the push rod 18, the valve 8 away from its seat 7, against a spring 19, which opens the passage of gas from the conduit 4 to the injector 6. On the contrary, when the winding 16 is no longer traversed by a current, the plunger core 17 and the push rod 18 are in the position indicated in the right half-view of FIG. 1, the valve 8 then being applied to its seat. 7 by the spring 19 and the passage of combustible gas interrupted.

In the control box 14, are also housed a current rectifier 20 and a printed circuit or equivalent ensuring the necessary electrical connections (not shown).

This box 14 is also provided with an electrical outlet 21, waterproof, with safety lock to which can be connected or disconnected with all the safety measures considered necessary or essential, an electrical connector 22 also waterproof and with lock of safety, provided with electrical supply conductors 23.

The electrical diagram for controlling the valve (according to FIGS. 2, 3) comprises, on the printed circuit of the control box 14, an arrival with two pads 24, 25 of single-phase alternating current (110 V 50 Hz or 220 V 50 Hz , etc.) from the normal network, in particular by a timed control member (not shown) and the electrical supply conductors 23.

From this arrival are supplied from inside the housing 14, the rectifier 20 supplying the coil 15 and also an igniter 26 which supplies. in high-discharge current, for example 15,000 V, a spark gap 27 placed in a gas ignition zone. Grounding of the circuits is advantageously carried out using a tab for grounding 28.

The electrical connection between the igniter 26, placed in the control box 14 and the spark gap 27, placed in a gas ignition zone is carried out using a high voltage output conductor 29. The connection of the tab 28 with the respective grounding terminal of the printed circuit inside the control box 14 is produced using a grounding conductor 30.

The operation of the valve is as follows:.

The valve being at rest, and all its parts in the normal rest position, as illustrated in the right half-view of FIG. 1, in particular the valve 8 applied to the seat 7, the timed control member, in particular a contactor manual or slaved to a thermostat, a control clock, a door opening device 'or any other similar control means, sends to the device the single-phase current which feeds by the printed circuit the rectifier 20 and the winding 16 of the coil 15. The plunger core 17 is displaced, which causes the concomitant displacement of the push rod 18 and therefore that of the valve 8 against the spring 19 in the direction of the opening of the gas passage between the conduit 4 and the injector ₆ .

The rectified current feeds, also by the connections of the printed circuit, the igniter-26 which sends to the spark gap 27 the electric heaters for ignition of the gas at the outlet of the injector 6. The gas is ignited and the injector in service.

The timed controller ceases to send the single-phase ignition control current after a relatively short time, but sufficient for the temperature of the thermocouple 12 to be high enough for the latter to send the current to the magnetic head. necessary for the valve 8 to be kept open.

The device is under the supervision of the thermocouple 12 until a failure or new conditions cause the combustion of the gas to stop and, therefore, the thermocouple to cool, the current in the head to stop. magnetic and closing the valve 8.

The electrical system of the device of this invention and Figures 2 and 3 comprise, in more detail, the rectifier 20 supplied as already mentioned and supplying rectified current, in parallel according to the embodiment of Figure 1 on the one hand l winding 16 of the coil 1e and on the other hand a set of high voltage sparks 31, according to any suitable method and device.

• -une résistance B, notammant une varistance ou tout autre composant ou ensemble de même fonction c'est-à-dire dont la résistivité est variable : élevée pour une tension inférieure égale ou voisine de la tension normale d'alimentation, décroissante notamment très fortement pour une tension s'élevant au-dessus de cette tension normale d'alimentation même pour une très courte durée,
• - un condensateur C ou tout autre ensemble ou composant de même fonction,
• - une diode à gaz D ou tout autre ensemble ou composant de même fonction c'est-à-dire de décharge périodique du condensateur C dans le primaire d'un transformateur E, et
• - le transformateur E ou tout autre ensemble ou composant de même fonction c'est-à-dire d'amplification de la tension de décharge du condensateur C,
  qui constituent en combinaison l'allumeur 26 et
• - l'éclateur 27 venant également en combinaison ou tout autre composant ou ensemble de même fonction, c'est-à-dire d'assurer la formation d'étincelles haute tension, comportant un . élément de masse G.

Rectifier 20 can in itself be the subject of very numerous variants and embodiments in particular but not exclusively that known comprising four diodes in staggered rows (in bridge) which has the advantage of making it possible to benefit from a more powerful rectified current. than that obtained by means of a simple diode which thus avoids any untimely vibration of the rectifier used on a coil or relay. However, the spark generation assembly 31 may include, by way of nonlimiting example as shown in the drawing to which reference is made explicitly and in a nonlimiting manner:

• a resistor B, in particular a varistor or any other component or assembly having the same function, that is to say one whose resistivity is variable: high for a voltage lower than or equal to the normal supply voltage, decreasing in particular very strongly for a voltage rising above this normal supply voltage even for a very short time,
• - a capacitor C or any other assembly or component with the same function,
• a gas diode D or any other assembly or component of the same function, that is to say of periodic discharge of the capacitor C in the primary of a transformer E, and
• the transformer E or any other assembly or component having the same function, that is to say amplifying the discharge voltage of the capacitor C,
  which constitute in combination the igniter 26 and
• - The spark gap 27 also coming in combination or any other component or assembly having the same function, that is to say ensuring the formation of high voltage sparks, comprising a. mass element G.

The electrical system then comprises, according to the present invention, integrated means of protection against transient overvoltages constituted by a “varistor J whose function is to limit the voltages and the shock currents, to address the disturbing energies and to stabilize the voltages, of whatever nature. To this varistor J is associated a lower resistance than the resistance B or any member or assembly of the same function, that is to say on the one hand not to disturb the operation of the capacitor C and on the other hand to attenuate the reactive voltage peaks of the transformer E primary.

The varistor J is placed, according to a first embodiment illustrated by FIG. 2, downstream of the rectifier 20, in parallel with on the one hand the coil 15 and on the other hand the igniter 26, in particular on the primary of the transformer E.

According to a second embodiment illustrated in FIG. 3, the rectifier 20 feeds directly only the coil 15. The spark production assembly 31 is supplied with current rectified by a spark diode 32.

The varistor J is placed in this second embodiment upstream of the rectifier 20, so as to protect the two circuits supplied separately with rectified current.

It will be observed that according to the invention, all the component members, electrical and electronic assemblies such as in particular coil 15, rectifier 20, igniter 26, printed circuit and respective connections (apart from spark gap 27 and lug 28) can be housed in the housing 14, in particular in the form of a single block, overmolded in resin or any other insulating body, compact waterproof and protected against dust and any other harmful or corrosive atmosphere. In this embodiment, the external connections are reduced to the conductors 11 of the thermocouple 12, of the power supply 23, of high voltage 29 and of grounding 30.

This arrangement also makes it possible, optionally and under certain conditions, to eliminate these external connection means outside the supply connections 23, in particular by making the spark gap 27 integral with the control box 14 and by integrating the grounding lug 28 in the coil magnetic circuit 15.

Claims (6)

1. Safety lighting device destined mainly to operate in relation with a valve (1), mainly for burners or radiating panels including a valve body (2) with a gaz inlet duct (4) and a recess for an injector (6) with a seat (7) for a valve (8) including on the first hand a safety body (9) with a magnetic head (10) fitted with a coil connected by an electric conductor (11) to a thermocouple (12) and on the other hand a control box (14) including a control coil (15) for the valve, a set (31) generating gas ignition sparks, a rectifier (20), a printed circuit, an earthing-tab (28) and integrated protection means against temporary overvoltage and in order to stabilise voltages, wherein the featuring protection means consisted in a varistor J destinated to protect the coil (15) controlling the valve and the spark generating set (31) and possibly the rectifier (20).

2. Ignition system according to claim 1, with a spark generating set including a resistance B, a condensor C, a gas diode D, a transformer E and a spark gap ; an igniter for this spark-gap and the control coil being supplied up in parallel by the rectifier wherein the varistor J is positioned after the rectifier (20), in parallel with the coil (15) and the igniter (26).

3. System according to claim 1 with a rectifier that supplies the valve control coil only as the spark generating set is supplied by a diode, wherein the varistor J is positioned before rectifier (20) and also in such a way but this rectifier is protected (20).

4. Ignition system according to claims 1 to 3, wherein the protection means against temporary over-voltages, coil (15), rectifier (20), igniter (26) for the spark generating set (31) printed circuit, and related connections are placed in the control box (14) as an overmoulded block in insulating material, compact, sealed and protected.

5. Ignition system according to claim 4, wherein the control box comprises a sealed socket (21) with a safety lock that can be connected.to the mains through a connector (22) which-is also sealed and fitted with a locking device and appropriate supply electric conductors (23); but- side connections being limited to conductors (11) of the high voltage (29) supply (23) thermocouple (12), and earthing (30) between tab (28) and control box (14).

6. Ignition system according to claims 4 and 5 wherein there is no conductors (11) for thermocouple (12), high voltage (29) and earthing (30) due to the fact that the spark gap (27) is built in the control box (14) and the tab (28) is part of the coil (15) magnetic circuit.

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