GB2100411A - Burner for gas cookers and hobs - Google Patents

Abstract

A burner for gas cookers and hobs, comprising a support (2) bearing a gas supply needle or injector (1) positioned in a chamber (5) defined by a sleeve (6), a body (12) supported on the sleeve (6) by means of radial fins, the body (12) having a central tubular portion (14) defining a through opening (15), and a flame spreader (13) supported on the body (12). Primary air for producing a gas-air mixture in the chamber (5) is drawn through a circumferential opening (18) defined between the peripheral edge (17) of the body (12) and the plate (9) of the hob and through radial passages between the tubular portion (14) and the sleeve (6) to mix with gas from the needle or injector (1) in the chamber (5), the gas-air mixture then being output through the opening (15), then spread between the surface (12') of body (12) and the surface (13') of spreader (13) and out through holes (21) in the flame spreader (13) for combustion. <IMAGE>

Description

SPECIFICATION Burner for gas cookers and hobs This invention relates to a burner for gas cookers and hobs in general.

Various types of gas burners for cookers and hobs are known, but these have the disadvantage, among others, that they are relatively tall, for which reason they are not suitable or cannot be used for hobs which must have the most compact and flat structure possible.

Furthermore in burners of the known type the channels for the primary air intake always lead downwards, more specifically below the hob, or towards the oven, in the case of cookers provided with an oven, or towards a chamber or in any event towards the intakes provided for the purpose below the hob.

In addition to this the fitting and centering of burners of the known type is rather laborious and difficult, and once fitted the burners have little stability and are therefore susceptible to undue movement.

Thus they are fitted in such a way that access to and dismantling of the needle and gas injector, when necessary, requires the removal or lifting of the top plate of the appliance or the removal of the front, with the result that the operation is never easy and convenient.

These known burners are also rather rigid in their operating capabilities, in that they only ensure correct combustion for given pressure and gas flow conditions, a factor which means that such burners are not suited to every appliance and therefore makes it necessary to have a range of different burners to suit all requirements.

The object of this invention is to produce a gas burner for cookers and hobs which comprises units which can be combined with ease, are conveniently accessible and are easily separable so as to eliminate the inconveniences and disadvantages of existing burners.

Another object of the invention is to seek to provide a burner including units shaped so as to produce the so-called Venturi effect in mixing and distribution of the gas, the said effect being obtained substantially between the support of the flame spreader and the flame spreader itself, in a radial direction and over a circular course from the centre towards the holes of the said flame spreader unit. This provides the'burner with considerable versatility and flexibility in use in that correct and complete combustion is maintained at all times even in the case of extensive gas pressure variations and with all types of gas. The burner is therefore suitable for all operating requirements and can be fitted to any cooker or hob.

A further object of the invention is to seek to provide a gas burner of very low height which can therefore be used with advantage in hobs which must be flat, or, in any event, as low as possible compatible with the installation requirements of the hob itself.

Yet another object of the invention is to seek to provide a burner in which the primary air for mixing is drawn from the exterior directly above the cooker top or hob, eliminating the provision of a closed and isolated box or air intakes below the said level as happens when traditional gas burners are used.

Yet another object of the invention is to seek to provide a gas burner which is easier to locate and centre and is stable when placed directly on the top of a cooker or hob or when fitted to a crossmember provided below the said top, the said burner also being capable of being fitted with a flame spreader of the conventional type, which is therefore easily available.

According to the present invention there is provided a burner for gas cookers and hobs, comprising a support bearing a gas supply injector or needle, a body associated with this support defining a chamber in which the gas is mixed with primary air drawn from the outside, and a flame spreader unit mounted on the said body defining therewith a passage for the supply of the gas-air mixture for burning through the holes of the said flame spreader, wherein the said support has a sleeve portion having a vertical axis and defining a chamber which is open at the top and closed at the bottom and contains the said injector or needle, the said sleeve having a peripheral flange by which it is securable to the plate of a cooker or hob, and the said sleeve being associated with a body having a tubular central portion defining a through opening, which is concentric with the said chamber, and a peripheral portion with an edge which extends downwards to lie proximate to the said plate, in use, defining therewith a circumferential passage for the intake of primary air above the said plate, the said body having radial passages for passing the primary air into the said chamber in order to form the gas-air mixture, and a flame spreader unit being supported on the said body overlying the hole in the tubular portion of the body itself, the upper surface of the said body and the internal surface of the said flame spreader unit, which are opposite to each other, define a radial passage of circular shape through which the gas-air mixture passes from the said through hole to the holes in the flame spreader with a suitable reduction in velocity and a recovery of pressure.

The present invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an example of a hob with gas burners; Figure 2 shows a cross-section of the burner assembly fitted directly to the hob with a primary air intake passage opening above the said hob; Figure 3 shows a partial cross-section along the line 111-Ill in Figure 2; and Figure 4 shows a cross-section similar to that in Figure 2 but with a gas burner which is fixed on a cross-member placed beneath the hob and in which the primary air intake opens downwards, The burner shown comprises a needle or gas injector 1 mounted on a support 2 which has a conduit 3 which can be connected via a connection piece 4 to a gas supply pipe (not shown).

In the embodirhent according to Figures 2 and 3, the injector or needle 1 is located within a chamber 5 which is defined by a sleeve portion 6 having a vertical axis. Thus chamber 5 is open at the top, but its base is closed by a wall 7. The sleeve portion 6 has an external peripheral flange 8 whereby the support 2 with the injector or needle 1 is fixed to a plate 9 which is, for example, the top plate of a gas cooker or the hob.

Flange 8 is fixed to plate 9 by means of screws 10 with an interposed packing seal 11.

The sleeve portion 6 of support 2 is associated with a removable body 12, which in turn acts as a support for a flame spreader unit 13 of known construction. This body 12 has a central tubular portion 14 defining a through opening 1 5 with a vertical axis and is provided externally with radial centering fins 1 6. The tubular portion 14 is intended to extend downwards into the chamber 5 of support 2 without reaching as far as the bottom wall 7. The said radial fins 16 are used for centering the said tubular portion 14 in the sleeve 6 in such a way that there are vertical passages 16 between the portion 14 and sleeve 1 6.

The removable body 12 also has a peripheral portion with an edge 17 which extends downwards to lie proximate to the surface of the plate 9, although at a distance from the latter so as to leave a circumferential passage 1 8 as an intake for the primary air necessary for mixing and combustion of the gas.

Radial ribs 19 constituting a support surface for body 12 are provided, on the upper edge of the sleeve portion 6 of support 2 bearing the injector or needle 1, and are located below body 12, between the central tubular portion 14 and the peripheral portion. These ribs 19 define radial passages in such a way that the primary air drawn from outside through the circumferential passage 18 can pass over the upper edge of the sleeve portion 6 to descend along passages 16 towards the bottom of chamber 5 and then rise again through the central opening 15 in body 12.

The primary air is drawn in from the outside of the burner directly above the plate 9 of the hob so as to obtain a gas-air mixture in chamber 5 and in the opening 15 of the flame spreader unit 13.

The body 12 also has on its intermediate upper part a circular rib 20 on which the flame spreader unit 13 is supported and centered so that the latter lies above the central opening 1 5.

The upper surface 12' of the body 12 and the 'internal surface 13' of the flame spreader 13 which are opposite each other may, depending on requirements, e.g. the pressure of the gas which is to be burnt, the type of gas, etc., be divergent, parallel, or convergent, from the centre towards the periphery or towards the series of holes 21 in the flame spreader 13. In any case, the said opposing surfaces 12' and 13' define a radial passage of circular extent 22 through which the gas-air mixture, which is produced in the central opening 15, is passed to the holes 21 of the flame spreader 13, where combustion occurs.In accordance with the Venturi effect, the velocity decreases and the pressure recovers, either as the result of the shape of passage 22 when this is given a particular divergent shape, or because the cross-section of the passage increases as a function of radius from the centre of the periphery. In this way the mixture is supplied and its combustion is correct and complete even in the case of major variations in the pressure and type of gas used.

The central opening 15 of the tubular portion 14 of body 12 may be advantageously fitted with a primary air regulator, this regulator being in the form of a sleeve 23 which can be moved and adjusted vertically in the said opening 15, and retained by a securing screw 24, so as to vary the height or distance from the bottom of chamber 5, as shown in Figure 2. A collar or rabbet may also be provided in the upper part of hole 1 5 in order to limit the upward movement of the sleeve 23 and to prevent the passage 22 from becoming completely closed.

Figure 4 of the drawing shows a burner of similar construction and operation to that described in relation to Figures 2 and 3, but in which the support 2' with the needle or injector 1 has a sleeve portion which is open at both the top and bottom. In this way the primary air is drawn from below or from under the hob, without the manner of mixing and distribution of the gas towards the holes of the flame spreader unit being altered.

It should also be noted that the burner described above can be fixed to a cross-member 25 below the surface of plate 9 as well as directly on this surface, see Figure 3, whenever this may be necessary or specified, just as the gas supply pipe may be arranged horizontally as shown in Figure 3, or vertically as shown in Figure 4.

In any event it can be seen from the above description and the drawing that the burner is of a low height and that it is possible to gain easy and direct access to the injector or needle, if this should require replacement, by removing the flame spreader 13 and the corresponding support 12, without having to alter the position of plate 9.

In the same way easy access can also be gained from above to the means for the regulation of gas flow comprising for example a butterfly valve 30 which is fitted as shown in Figure 3 in the drawing, in the gas supply pipe.

Claims (7)

Claims

1. A burner for gas cookers and hobs, comprising a support bearing a gas supply injector or needle, a body associated with this support defining a chamber in which the gas is mixed with primary air drawn from the outside, and a flame spreader unit mounted on the said body defining therewith a passage for the supply of the gas-air mixture for burning through the holes of the said flame spreader, wherein the said support has a sleeve portion having a vertical axis and defining a chamber which is open at the top and closed at the bottom and contains the said injector or needle, the said sleeve having a peripheral flange by which it is securable to the plate of a cooker or hob, and the said sleeve being associated with a body having a tubular central portion defining a through opening which is concentric with the said chamber, and a peripheral portion with an edge which extends downwards to lie proximate to the said plate, in use, defining therewith a circumferential passage for the intake of primary air above the said plate, the said body having radial passages for passing the primary air into the said chamber in order to form the gas-air mixture, and a flame spreader unit being supported on the said body overlying the hole in the tubular portion of the body itself, the upper surface of the said body and the internal surface of the said flame spreader unit, which are opposite to each other, define a radial passage of circular shape through which the gas-air mixture passes from the said through hole to the holes in the flame spreader with a suitable reduction in velocity and a recovery of pressure.

2. A burner according to claim 1, in which the said radial passage of circular shape is bounded by the upper surfaces of the said body which diverge from the centre towards the periphery within the flame spreader unit.

3. A burner according to claim 1, in which the said radial passage of circular shape is bounded by the upper surfaces of the said body which are parallel to each other within the said flame spreader unit.

4. A burner according to claim 1, in which the said radial passage of circular shape is bounded by the upper surfaces of the said body which converge from the centre towards the periphery within the said flame spreader.

5. A burner according to claim 1 and to any one of claims 2 to 4, in which a regulator for the intake of primary air, which can be adjusted in height above the bottom of the chamber with a closed base, is located in the said through opening.

6. A burner according to claim 1 and any one of claims 2 to 5, in which the said chamber defined by the sleeve portion has an open base for the simultaneous intake of primary air from beneath or from below the surface on which the burner is fixed.

7. A burner substantially as herein described with reference to and as illustrated in Figures 1 to 3 or Figure 4 of the accompanying drawings.