GB1575889A - Safety pilotlight assemblies - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO SAFETY PILOT-LIGHT ASSEMBLIES (71) We, SOURDILLON, a French Body Corporate of, Veigne, 37250 Montbazon, France, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to assemblies of the safety pilot-light type for gas appliances.

Atmosphere-monitoring pilot-lights are known in which the flame, which acts remotely on suitable safety valves, is adapted to be extinguished when the ambient atmosphere oxygen content is reduced (e.g. as in gas heaters), the gas supply automatically being cut off in such cases. It is common knowledge that these pilot-lights, which are very sensitive, are often combined with a flap system controlled by a bimetallic strip, such system being adapted to reduce the primary air intake to the pilot-light, and hence its sensitivity, on ignition of the pilotlight, the assembly opening automatically by the action of the bimetallic strip to restore the normal primary air intake as soon as the pilot light has heated up, and give it the sensitivity required for its correct operation.

Such assembles have certain disadvantages and in particular are difficult to adjust.

An object of the invention, inter alia, is to obviate these disadvantages and make the flap operation more effective without complicated adjustment.

According to the present invention there is provided a safety pilot-light assembly for gas appliances, comprising a pilot light whose flanme is adapted to co-operate with a thermostat or like device, having at least one primary air intake port and at least one secondary air intake port, the secondary air intake port being automatically adjustable by means of a temperature sensitive element characterised in that the secondary air intake port has associated therewith a flap which is arranged to close said secondary air intake port on ignition and which is separate from the temperature sensitive element, and which is arranged to open under the influence o fthe temperature sensitive element by a lever action in response to an increase in temperature.

The temperature sensitive element may be a bimetallic strip.

According to one advantageous embodiment the flap is of flat shape being adapted to bear against the seat, also having flat edges on the barrel.

The arrangement may be such that the bimetallic strip acting on the end of the flap tends to close it in substantially airtight manner in the pilot-light ignition position (the primary air then arrives via a suitable passage of reduced section) while as soon as the pilot-light heats up the bimetallic strip acting in the opposite direction fully opens the flap with a suitable amplification by the lever action.

The barrel is advantageously made as a metal pressure diecasting, since this makes it difficult for dust to adhere.

Finally, the pilot-light tube is advantageously fitted by a clip system which can also lock the bimetallic strip in position, thus avoiding a screw and nut connection.

Apart from these features, the invention includes certain other features which are preferably used at the same time and which will be discussed more explicitly hereinafter.

The invention will be described now by way of example only with particular reference to the accompanying drawing. In the drawing: Figure 1 is a diagrammatic section of an atmosphere monitoring unit of known type, and Figure 2 is a similar view to Figure 1 showing an atmosphere monitoring pilotlight constructed according to the inven tion.

The embodiment to be described is an atmosphere-monitoring pilot-light for a gas appliance.

For illustrative purposes, Figure 1 shows a pilot-light of this kind of known type which consists essentially of: A pilot-light tube 1 connected to a barrel 2 fed by an injector 3, which receives the gas (natural gas or town gas etc) via a pipe 4.

Means for introducing primary air into the barrel, such means comprising, inter alia, a port 5 for air intake on ignition; A flap 6 controlled by a bimetal or bimetallic strip 7, 8 which holds the flap 6 closed or substantially closed on ignition, while it opens the flap as a result of the heating effect due to the temperature surrounding the pilot light. This temperature is produced by the heat evolved by the burner or the pilot-light incorporated in the heater; and a safety device which is fed by the flame 9 and comprises a sensitive member 10, e.g. a thermocouple, for remote-control of a safety valve 11 of the magnetic or some other type.

In an assembly of this kind, the flame 9 is influenced by the atmosphere and, for a given adjustment, it tends to go out when the oxygen content of the atmosphere is reduced (or if the gas supply is cut off).

It has been found that correct operation of the flap 6 is difficult to obtain and, inter alia, the control of the closure position varied with the opening of the bimetallic strip.

To obviate these disadvantages, the present bimetallic strip is subjected to the action of means which amplify the flap movement.

In a specific embodiment shown in Figure 2 the barrel 2 has a projection 12 extending through an aperture in the flap 6 and the arm 8 of the bimetallic strip acts, at its end, on the shank 61 of the flap 6 in either direction depending upon whether it is heating up or cooling.

For this purpose, the end 81 of the bimetallic strip portion 8 is engaged between the end 61 of the flap 6 and another hookshaped end 13 of the flap.

The flap is advantageously in the form of a flat metal plate adapted to bear against a seat 14, whose edges are also situated on a corresponding flat surface.

The port through which the primary air is introduced on ignition is shown at 5 in one of the walls of the barrel, and the port could also be provided in the flap 6.

The bimetallic strip is so adjusted that in the cold position, i.e. before ignition, it exerts on the end of the flap 6, i.e. at 13 in the drawing, a force which tends to apply the flap 6 firmly to its seat while when the bimetallic strip heats up it assumes the position shown in chain-dotted lines and rapidly causes the flap to open as a result of the boosting effect produced by the lever arrangement operative about the projection 12.

This arrangement gives an ideal operation since there is always a closure pressure when the pilot light is cold, i.e. before ignition, the closure thus being air-tight.

The barrel 2 is advantageously a metal pressure diecasting since this avoids dust adhesion as a result of its clearance angles as compared with barrels made by conventional machining processes, and also enables the barrel to be readily fitted by means of clips.

For example, in the embodiment shown, the barrel 2 comprises a socket 15 into which the tube 1 is fitted and held therein by means of a ring 16 fitted thereover and held in place by a clip device 17 engaging, for example, in the aperture 5.

This device allows very simple installation of the bimetallic strip which, for example, has its own abutment base 18 fitted initially to the tube 1 and held in position there by the ring 16 and clip system 17.

Similarly, fitting of the flap 6 is made very simple because all it needs is an aperture 69 which will fit over the projection or nose 12.

The present assembly has numerous advantages, more particularly as follows: It enables the flap to be closed so that it is air-tight.

No adjustment or calibration operations as required on conventional flap systems are necessary.

Rapid opening is possible as a result of the boosting or amplification of the movement produced by the lever effect, so that after ignition the pilot light very rapidly reaches sensitivity conditions, i.e. metastability conditions.

The assembly is extremely quick to fit.

The cost price can be reduced because machining processes are not used.

Finally, dust adhesion is obviated by the use of barrels made of a cast material (by pressure or any other process).

WHAT WE CLAIM IS: 1. A safety pilot-light assembly for gas appliances, comprising a pilot light whose flame is adapted to co-operate with a thermostat or like device, having at least one primary air intake port and at least one secondary air intake port, the secondary air intake port being automatically adjustable by means of a temperature sensitive element characterised in that the secondary air intake port has associated therewith a flap which is arranged to close said secondary

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. tion. The embodiment to be described is an atmosphere-monitoring pilot-light for a gas appliance. For illustrative purposes, Figure 1 shows a pilot-light of this kind of known type which consists essentially of: A pilot-light tube 1 connected to a barrel 2 fed by an injector 3, which receives the gas (natural gas or town gas etc) via a pipe 4. Means for introducing primary air into the barrel, such means comprising, inter alia, a port 5 for air intake on ignition; A flap 6 controlled by a bimetal or bimetallic strip 7, 8 which holds the flap 6 closed or substantially closed on ignition, while it opens the flap as a result of the heating effect due to the temperature surrounding the pilot light. This temperature is produced by the heat evolved by the burner or the pilot-light incorporated in the heater; and a safety device which is fed by the flame 9 and comprises a sensitive member 10, e.g. a thermocouple, for remote-control of a safety valve 11 of the magnetic or some other type. In an assembly of this kind, the flame 9 is influenced by the atmosphere and, for a given adjustment, it tends to go out when the oxygen content of the atmosphere is reduced (or if the gas supply is cut off). It has been found that correct operation of the flap 6 is difficult to obtain and, inter alia, the control of the closure position varied with the opening of the bimetallic strip. To obviate these disadvantages, the present bimetallic strip is subjected to the action of means which amplify the flap movement. In a specific embodiment shown in Figure 2 the barrel 2 has a projection 12 extending through an aperture in the flap 6 and the arm 8 of the bimetallic strip acts, at its end, on the shank 61 of the flap 6 in either direction depending upon whether it is heating up or cooling. For this purpose, the end 81 of the bimetallic strip portion 8 is engaged between the end 61 of the flap 6 and another hookshaped end 13 of the flap. The flap is advantageously in the form of a flat metal plate adapted to bear against a seat 14, whose edges are also situated on a corresponding flat surface. The port through which the primary air is introduced on ignition is shown at 5 in one of the walls of the barrel, and the port could also be provided in the flap 6. The bimetallic strip is so adjusted that in the cold position, i.e. before ignition, it exerts on the end of the flap 6, i.e. at 13 in the drawing, a force which tends to apply the flap 6 firmly to its seat while when the bimetallic strip heats up it assumes the position shown in chain-dotted lines and rapidly causes the flap to open as a result of the boosting effect produced by the lever arrangement operative about the projection 12. This arrangement gives an ideal operation since there is always a closure pressure when the pilot light is cold, i.e. before ignition, the closure thus being air-tight. The barrel 2 is advantageously a metal pressure diecasting since this avoids dust adhesion as a result of its clearance angles as compared with barrels made by conventional machining processes, and also enables the barrel to be readily fitted by means of clips. For example, in the embodiment shown, the barrel 2 comprises a socket 15 into which the tube 1 is fitted and held therein by means of a ring 16 fitted thereover and held in place by a clip device 17 engaging, for example, in the aperture 5. This device allows very simple installation of the bimetallic strip which, for example, has its own abutment base 18 fitted initially to the tube 1 and held in position there by the ring 16 and clip system 17. Similarly, fitting of the flap 6 is made very simple because all it needs is an aperture 69 which will fit over the projection or nose 12. The present assembly has numerous advantages, more particularly as follows: It enables the flap to be closed so that it is air-tight. No adjustment or calibration operations as required on conventional flap systems are necessary. Rapid opening is possible as a result of the boosting or amplification of the movement produced by the lever effect, so that after ignition the pilot light very rapidly reaches sensitivity conditions, i.e. metastability conditions. The assembly is extremely quick to fit. The cost price can be reduced because machining processes are not used. Finally, dust adhesion is obviated by the use of barrels made of a cast material (by pressure or any other process). WHAT WE CLAIM IS:

1. A safety pilot-light assembly for gas appliances, comprising a pilot light whose flame is adapted to co-operate with a thermostat or like device, having at least one primary air intake port and at least one secondary air intake port, the secondary air intake port being automatically adjustable by means of a temperature sensitive element characterised in that the secondary air intake port has associated therewith a flap which is arranged to close said secondary

air intake port on ignition and which is separate from the temperature sensitive element, and which is arranged to open under the influence of the temperature sensitive element by a lever action in response to an increased in temperature.

2. An assembly as claimed in claim 1 wherein said temperature sensitive element is a bimetallic strip.

3. An assembly according to claim 1 or claim 2 characterised in that the lever action is produced by the flap itself, which is mounted pivotally, one of its parts co-operating with a seat and the other, on the side remote from the pivot, being operable by the temperature sensitive element.

4. An assembly according to claim 3 characterised in that the flap is of flat shape and is applied to a seat having likewise flat edges, which is provided on a barrel of the assembly.

5. An assembly according to any one of claims 1 to 4 characterised in that the temperature sensitive element acts on that end of the flap which is remote from its operative part, with respect to the pivot, by tending to close the flap in an air-tight manner when the pilot-light is in the ignition position, while as soon as the pilotlight has heated up the element acts in the opposite direction to fully open the flap with amplification of the movement by the lever action.

6. An assembly according to any one of claims 1 to 5 characterised in that the pilotlight tube assembly comprises a clip device which also locks the temperature sensitive element in position.

7. An assembly according to claim 6 when appendent to claim 4 characterised in that the clip is applied to the edges of an aperture which can be used for the intake of primary air into the barrel in the cold state.

8. An assembly according to claim 4 characterised in that the barrel is made from a cast material.

9. A safety pilot-light assembly for gas appliances substantially as hereinbefore described with reference to and as shown in Figure 2 of the accompanying drawing.