GB1568236A - Gas burners - Google Patents

Description

(54) IMPROVEMENTS RELATING TO GAS BURNERS (71) We, MAIN GAS APPLIANCES LIMI TED, a British company of Thorn House, Upper Saint Martin's Lane, London, WC2H 9ED, 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 gas burners adapted for spark ignition.

In accordance with this invention there is provided a gas burner adapted for spark ignition by means of a first electrode which is formed of sheet metal and extends around at least a major portion of the burner, the first electrode providing with a second electrode a plurality of possible sparking points around the burner.

With a burner of this type, a spark can occur at a number of points around the burner, either at random positions or at selected points adjacent individual burner ports. Nevertheless the burner construction is both economical and robust, involving as it does the use of sheet metal for the first electrode.

As compared with conventional burners which use a wire electrode, the electrode is less likely to be damaged during cleaning, and the multiplicity of possible sparking points increases the likelihood of one remaining operational even if the electrode is damaged or the gas supply to some outlet ports is blocked.

The invention will now be described by way of example with reference to the drawings accompanying the Provisional Specification in which each of the Figures 1 to 4 is a crosssectional view through a respective gas burner embodying the invention.

Figure 1 shows a gas burner 10 fitted into a recess in the hot-plate or hob 12 of a gas cooker. The main body of the burner is made of sheet metal sections. A section 14 is attached to the lower side of the hot-plate 12 and communicates with the end of an inlet duct 16 through which a gas/air mixture passes. A section 18 is above the hot-plate and has a ring of ports 20 through which the gas/ air mixture escapes to be burnt. Just above the ring of ports 20 is a ceramic electricallyinsulating disc 22 of diameter slightly larger than the diameter of the burner section 18.

Over this is positioned a sheet metal circular electrode member 24 which extends at the periphery slightly below the ceramic disc 22 and forms part of the top of the burner.

The ceramic disc 22 with the electrode member 24 are secured to the burner by means of a bolt 26 extending through an aligned hole in the disc 22 and member 24 and also through the bottom of the inlet duct 16. A nut 28 can be tightened against an insulator 30 which forms a gas-tight seal against the duct while electrically insulating the bolt 26 from it. Finally a decorative plate32 is a push fit onto the top of the electrode 24 to cover the end of the bolt 26.

In use a high tension electrical source is connected by any suitable means to the bottom of the bolt 26 and thereby to the electrode member 24, the latter being electrically insulated from the burner body and the hob.

The other terminal of the source may be connected to the body of the cooker. Thus when the source is activated a spark will be formed between the periphery of the electrode member 24 and the top portion of the burner body section 18, in the region 34. This spark will occur at a multitude of positions around the periphery of the burner thus increasing the chances or ofignition taking place.

The periphery of either the electrode member 24 or the section i8 may be slightly fluted, to - encourage sparks to be formed adjacent the outlet ports 20.

The application of a similar arrangement to three further types of burner will now be described with reference to Figures 2, 3 and 4. Only the difference from the Figure 1 arrangement will be described in detail, and the same references will be used where applicable.

In Figure 2 a supply of secondary air is provided up the middle of the burner. For this purpose a sheet metal tube 42 is attached to the inlet duct and permits air entering the bottom of the tube to escape through ports 44 immediately above the burner outlet ports 20.

In this example a nut 46 holds the electrode member 24 onto the ceramic disc 22. The nut 28 is not shown on Fig. 2, and the insulator 30 takes the form of a spider with channels to permit the flow of air.

The burner 50 of Figure 3 has a conventional ceramic burner cap 52 replacing the disc 22 of Figure 1. The cap 52 can include or can be without ports. With this arrangement the spark is formed between the periphery of the electrode member 24 and the top of the burner section 18 over the peripheral surface of the cap 52, as indicated at 54.

Finally Figure 4 shows a burner 60 similar to Figure 2 but with some parts of modified shape. In particular, a separate upper burner section 18 is formed with a series of outlet ports 20 slanted as shown, and additional air outlet 44 is a slightly different shape.

The burners illustrated are particularly suitable for use with flame sensing systems of the type in which a flame is detected by either its rectifying or its ionizing effects. In known arrangements, if the flame at the electrode or point of sensing is blown away but it is not out all around the burner reignition or shut-off will occur unnecessarily.

With the illustrated burners, as long as a flame exists somewhere around the burner it will be sensed.

The burners of Figures 1, 2 and 4 have particular advantages in that the tracking path between the electrodes (i.e. the short circuit path along the surfaces of the insulators between them) is well protected from spillage of fluids over the burners, due to the fact that the periphery of the electrode 24 extends below the periphery of the ceramic disc 34. In Figure 4 the tracking path is substantially shorter than the spark gaps thus reducing the likelihood of tracking occurring.

WHAT WE CLAIM IS: 1. A gas burner adapted for spark ignition by means of a first electrode which is formed of sheet metal and extends around at least a major portion of the burner, the first electrode providing with a second electrode a plurality of possible sparking points around the burner.

2. A gas burner according to claim 1, wherein the first electrode is disc-shaped and forms part of the top of the burner.

3. A gas burner according to claim 2, wherein the first electrode is supported on a ceramic support.

4. A gas burner according to claim 3, wherein the first electrode extends at its periphery slightly below the periphery of the ceramic support.

5. A gas burner according to claim 2, 3 or 4, wherein the first electrode is held in position by a conductive elongate fastening member secured to its centre.

6. A gas burner according to claim 6, including a cover over the central part ofthe electrode disc.

7. A gas burner according to any of claims 2 to 6, wherein the first electrode is fluted to encourage sparks to be formed adjacent the burner outlet ports.

8. A gas burner according to any preceding claim, wherein the second electrode is constituted by a portion of the burner body.

9. A gas burner according to any preceding claim, wherein the burner outlet ports are formed in a sheet metal section.

10. A gas burner constructed substantially as herein described with reference to any of the figures of the drawings accompanying the Provisional Specification.

11. A gas burner according to any preceding claim, provided with a flame sensor coupled to the electrodes to detect the presence of a flame by its rectifying or ionizing effects.

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

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. member 24 onto the ceramic disc 22. The nut 28 is not shown on Fig. 2, and the insulator 30 takes the form of a spider with channels to permit the flow of air. The burner 50 of Figure 3 has a conventional ceramic burner cap 52 replacing the disc 22 of Figure 1. The cap 52 can include or can be without ports. With this arrangement the spark is formed between the periphery of the electrode member 24 and the top of the burner section 18 over the peripheral surface of the cap 52, as indicated at 54. Finally Figure 4 shows a burner 60 similar to Figure 2 but with some parts of modified shape. In particular, a separate upper burner section 18 is formed with a series of outlet ports 20 slanted as shown, and additional air outlet 44 is a slightly different shape. The burners illustrated are particularly suitable for use with flame sensing systems of the type in which a flame is detected by either its rectifying or its ionizing effects. In known arrangements, if the flame at the electrode or point of sensing is blown away but it is not out all around the burner reignition or shut-off will occur unnecessarily. With the illustrated burners, as long as a flame exists somewhere around the burner it will be sensed. The burners of Figures 1, 2 and 4 have particular advantages in that the tracking path between the electrodes (i.e. the short circuit path along the surfaces of the insulators between them) is well protected from spillage of fluids over the burners, due to the fact that the periphery of the electrode 24 extends below the periphery of the ceramic disc 34. In Figure 4 the tracking path is substantially shorter than the spark gaps thus reducing the likelihood of tracking occurring. WHAT WE CLAIM IS:

1. A gas burner adapted for spark ignition by means of a first electrode which is formed of sheet metal and extends around at least a major portion of the burner, the first electrode providing with a second electrode a plurality of possible sparking points around the burner.

2. A gas burner according to claim 1, wherein the first electrode is disc-shaped and forms part of the top of the burner.

3. A gas burner according to claim 2, wherein the first electrode is supported on a ceramic support.

4. A gas burner according to claim 3, wherein the first electrode extends at its periphery slightly below the periphery of the ceramic support.

5. A gas burner according to claim 2, 3 or 4, wherein the first electrode is held in position by a conductive elongate fastening member secured to its centre.

6. A gas burner according to claim 6, including a cover over the central part ofthe electrode disc.

7. A gas burner according to any of claims 2 to 6, wherein the first electrode is fluted to encourage sparks to be formed adjacent the burner outlet ports.

8. A gas burner according to any preceding claim, wherein the second electrode is constituted by a portion of the burner body.

9. A gas burner according to any preceding claim, wherein the burner outlet ports are formed in a sheet metal section.

10. A gas burner constructed substantially as herein described with reference to any of the figures of the drawings accompanying the Provisional Specification.

11. A gas burner according to any preceding claim, provided with a flame sensor coupled to the electrodes to detect the presence of a flame by its rectifying or ionizing effects.