GB2298915A - A gas burner - Google Patents

Abstract

A gas burner comprises an inlet chamber 2 and a main chamber 1, the inlet chamber including means 6 for receiving combustible gas and an air inlet 8 through which air is drawn by the combustible gas, the main chamber comprising a plurality of walls including a peripheral wall which has a plurality of flame holes 5 opening into main chamber and a conduit 10 disposed within the main chamber and extending from the inlet chamber for directing a mixture of the combustible gas and air from the inlet chamber into the main chamber at a position remote from the inlet chamber. The entrance to the conduit is universally flared so that the velocity of the gas increases as it enters the conduit. The upper surface of the chamber 1 overhangs 15 the peripheral walls.

Description

A GAS BURNER This invention relates to gas burners, and in particular to gas burners for use in barbecues, flame grills and the like. The burner may be used indoors or outdoors.

One conventional gas burner for a barbecue includes a gas distributor which directs gas to a series of outlet holes. The gas is fed to the distributor from beneath the barbecue. This has the disadvantage that the whole barbecue must be disassembled in order to remove the burner.

Furthermore, the conventional burner is usually very deep necessitating a correspondingly deep barbecue housing to accommodate the depth of the burner.

The present invention is defined in the appended claims.

Embodiments of the present invention are described below by way of example, and with reference to the accompanying drawings in which: Figure 1 is a perspective top view of the gas burner according to a first embodiment; Figure 2 is a perspective underside view of the gas burner according to the first embodiment; Figure 3 is an underside view of the gas burner according to the first embodiment and showing, with a broken line, an internal conduit; Figure 4 is a sectional side view of the gas burner according to the first embodiment; Figure 5 is a side view of the internal conduit; Figure 6A, 6B and 6C are views of an inlet chamber; Figure 7 is a schematic view of burner units connected together; and Figure 8 is a view of a blank from which a lower piece of a main chamber is fabricated.

Referring to Figures 1 and 2, a gas burner is shown including a main chamber 1 and an inlet chamber 2. The inlet chamber 2 includes an aperture 6 opening into the inlet chamber 2. A source of combustible gas may be connected to the aperture 6 for directing the gas into the inlet chamber 2 at velocities which are typically of the order of 130 - 140 miles per hour.

Referring now to Figure 4, the gas directed into the inlet chamber 2 passes into a conduit 10. The entrance of the conduit 10 is inwardly flared such that the velocity of gas increases as it enters and is constricted by the conduit 10. This flow of gas causes ambient air to be drawn into the inlet chamber 2 via an air inlet 8. This air forms a combustible mixture with the gas and exits from the conduit 10 directly into the main chamber 1 at a position remote from the inlet chamber. The conduit 10 delivers the air and gas generally centrally within the main chamber 1 thereby producing an even distribution of gas within the main chamber 1.

Referring to Figures 1, 2, 3 and 4, the main chamber 1 includes peripheral walls 3, an upper wall 4 and a lower wall 11. The peripheral wall 3 includes a series of equally spaced flame holes 5 opening into the main chamber 1. In use, gas and air escapes from the main chamber 1 via these holes 5 and the escaping gas and air is burnt to create flames. Each flame hole 5 is disposed close to an adjacent flame hole 5 so that when the gas and air escaping from one flame hole 5 is lit, the flames will spread to the gas and air escaping from the adjacent flame hole 5. This enables the whole burner to be lit by 'cross-fire'. The holes are typically 7.14 +/-3 mm apart, and 2.0 +/-1 mm in diameter.

The main chamber 1 is rectangular and the flame holes 5 nearest the corners of adjacent walls are located very close to those corners so that cross-fire will occur right around the main chamber 1. Typically the centre of each cornermost flame hole 5 is disposed 3.0 +/-1 mm from the corner.

It is important to make the holes of the appropriate size so that the correct flame shape is achieved. This helps to reduce carbon monoxide emissions. From Figure 4, it will be seen that the conduit 10 is positioned with the main chamber 1 so that its axis of symmetry is slightly below the line of flame holes 5.

The upper wall 4 of the main chamber 1 is flat and overhangs the peripheral walls 3 so that during cooking any fat which falls onto the upper wall 4 will not run down the peripheral wall 3 where it might obstruct the flame holes 5.

The overhang 15 may be turned downwardly so that fat will drip from the end of the overhang 15.

Referring to Figures 2, 3 and 4, the lower wall 11 includes a bolt 9 extending outwardly therefrom. The bolt is used to secure the burner safely to a base. In this case, the burner is secured to a barbecue below a grill tray upon which food is cooked.

Referring to Figure 7, three burner units 22 are shown connected up to a gas rail or gas feed 21. A valve 20 is disposed between the gas feed 21 and each burner unit 22.

More burner units 22 may be placed on the gas feed 21 depending on the size of the barbecue or flame grill. The gas is supplied to one end of each gas burner unit 22 so that it is relatively simple to assemble the barbecue.

Conventional barbeques supply the gas from underneath which makes connection of the burner units to the gas supply difficult. The gas supply may be derived from gas bottles or from mains gas.

In Figure 7, the burner units 22 are shown lying parallel to each other. In another embodiment, not shown, the burner units 22 are arranged radially around a central gas distribution unit. Alternatively, the radially arranged burner units 22 may be fed from a ring gas feed passing around the burner units 22.

Figures 3, 4 and 6A - 6C show the inlet chamber 2 in more detail. The gas supply is attached to the aperture 6, typically by use of a short length of pipe which is pushed a short distance through the aperture 6, and is a push-fit therein.

The air inlet 8 opens into the inlet chamber 2 so that the flow of gas through the inlet chamber 2 draws ambient air into the inlet chamber 2. The size of the air inlet 8 is governed by the proportion of air required for combustion in the air/gas mixture which passes into the main chamber 1.

In this embodiment the air inlet hole is 25 +/-10 mm long, and 3.75 +/-2 mm wide. Efficiency of the burner is improved if the correct air/gas mixture is achieved, and less carbon monoxide will be produced.

Referring to Figures 3, 4 and 5, the gas and air mixture passes through the conduit 10. The conduit 10 delivers the air and gas directly into the main chamber 1.

The conduit is disposed entirely within the main chamber with the exception of the very tip of the flared end which is located against an outer wall of the main chamber 1. In order that flames from the flame holes are even, the pressure of air and gas at every flame hole 5 should ideally be identical. To achieve a reasonably even pressure at every flame hole 5, the conduit 10 extends about one third of the length of the main chamber 1 so that about two thirds of the air and gas is passed towards the end of the main chamber 1 remote from the inlet chamber 2, and about one third of the air and gas is thrown towards the end of the main chamber 1 nearest to the inlet chamber 2.

The gas burner is constructed from four pieces of metal, in this case stainless steel. The main chamber 1 is constructed from a lower piece which forms the lower wall 11, and the peripheral walls 3, and an upper piece which forms the top wall 4. The lower piece, shown in Figure 8, is formed by cutting an X shaped blank 32 from a sheet of metal. A hole for passage of the conduit and flame holes are punched or otherwise formed in the blank (not shown). The blank 32 includes four wings 3,31 extending from a central portion 33. The wings 3,31 are bent upwards along a fold line 34 so that each wall 3 meets adjacent walls to form corners. The part of the wings labelled 31 are then bent outwardly by ninety degrees to form a flange extending outwardly around the rim of the lower piece. The walls 3 are brazed or otherwise joined at the corners.

The upper piece (not shown) is also formed by cutting a blank into an X shape. Three of the four wings of the blank are folded over on themselves so as to form U-shaped channels. The upper piece is mounted on to the lower piece by sliding the flanges 31 of the lower piece 32 into the channels of the upper piece. The channels are then crimped closed to hold the flange therein. The upper and lower pieces may also be brazed together. The channel and flange form the overhang which diverts fat away from the flame holes 5.

The conduit 10 is made as one piece, and is inserted through the appropriate hole in a peripheral wall 3 from outside the main chamber 1. The flared end of the conduit 10 is seated against the hole. The conduit 10 may be held in place by spot welding or brazing.

The inlet chamber 2 is formed from a single blank (not shown) of metal cut from a metal sheet. The blank is X shaped and the gas aperture 6 is drilled or punched into a central portion of the blank. The blank includes the central portion, and four wings extending from the central portion. Each wing is bent upwardly by ninety degrees so that the four wings meet at their edges. Two opposite wings are longer than the other two wings. The extra length is bent outwards by ninety degrees from the wings so as to form two flanges 7 shown in Figure 1.

The inlet chamber 2 is attached to the main chamber 1 by a weld joint between the flanges 7 and a peripheral wall 3 of the main chamber 1, as shown in Figure 1. One of the wings forming the lower surface of the inlet chamber 2 is shorter than the opposite wing so that a gap exists between the lower surface and the peripheral wall 3 of the main chamber 1. This gap forms the air inlet 8.

According to another embodiment, the top wall 4 is cambered so that any fat which drips onto the top wall 4 runs off the overhanging edge.

According to a further embodiment, the peripheral wall is continuous so that the corners are replaced by a continuous curved wall. This arrangement assists in crossfire during ignition.

Claims (5)

1. A gas burner comprising an inlet chamber and a main chamber, the inlet chamber including means for receiving combustible gas and an air inlet through which air is drawn by the combustible gas, the main chamber comprising a plurality of walls including a peripheral wall which has a plurality of flame holes opening into main chamber and a conduit disposed within the main chamber and extending from the inlet chamber for directing a mixture of the combustible gas and air from the inlet chamber into the main chamber at a position remote from the inlet chamber.

2. A gas burner according to claim 1, wherein the plurality of walls includes a second wall having an overhang region which overhangs the peripheral wall.

3. A gas burner according to claim 1 or 3, wherein the conduit includes a first flared end which is flared inwardly relative to the direction of flow of the mixture of the combustible gas and air from the inlet chamber.

4. A gas burner according to any preceding claim wherein the main chamber is fabricated from sheet material.

5. A gas burner constructed and arranged substantially as described with reference to the accompanying drawings.