GB2170001A - Burners for domestic gas fire - Google Patents

Abstract

A fire has burners 12, 12' each having a hollow elongate mixing chamber 16 with gas and air nets 22, 24 and a conical diffusing shield 36 arranged over and projecting beyond the outlet from the chamber to spread the flames therefrom. The gas and air supplies to the burners may be independently controllable. The shields are suitable for a log effect fire with distributed flames. <IMAGE>

Description

SPECIFICATION Improvements in or relating to combustion assemblies The present invention concerns improvements in or relating to combustion assemblies, especially but not exclusively burners for gaseous fuel and more especially but not exclusively burners for domestic gas fires of the coal or log effect type.

Existing domestic gas fires of the coal or log effect type operate on the principal of burning a gas jet below incombustible artificial logs or coal lumps.

In such fires it is desirable to have a flame effect and this is provided by burning a gas/air mixture with a very high gas content. Whereas this gives a good visible flame it is extremely thermally ineffi cient and in addition creates soot.

An additional difficulty with existing fires of this type is to spread flames throughout the coal or log display. Normally flames tend to be localised, any distribution thereof from the burners being as a result of the physical arrangement of the components of the display and this often leads to a compromise between a good display arrangement and a good flame pattern.

It is an object of the present invention to obviate or mitigate these disadvantages.

According to a first aspect of the present invention there is provided a burner for gaseous fuel comprising a hollow elongae mixing chamber into which fuel and air are introduced and a diffusing shield arranged over and projecting laterally beyond the outlet from the chamber.

Preferably the chamber is cylindrical and the diffusion shield is dome-shaped or conical.

Preferably a flange is provided around the outlet from the chamber, the flange, together with the shield, defining an annular discharge passage directed generally radially outwardly from the chamber.

The chamber may be provided with means for varying the gas/air mixture, for example an air inlet regulator.

According to a further aspect of the present invention there is provided a fire for gaseous materials including at least two burners, the burners each comprising a hollow elongate mixing chamber into which fuel and air are introduced and a diffusing shield arranged over and projecting laterally beyond the outlet from the chamber.

Preferably independently operable air inlet regulating means are provided for each burner. Alternatively only the front burner, in use, has air regulating means.

Preferably each burner comprises a cylindrical body having air inlet passages formed therein, the air regulating means comprising a cylindrical sleeve, with a corresponding number of air passages therethrough, arranged round the burner body and movable relative to the burner body to progressively open to mask off the air inlet passages in the body.

Preferably the burners are arranged in a tray adapted to support a simulated coal or log fire.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawing which is a diagrammatic cross-sectional elevation through the burner assembly of a log/coal effect domestic gas fire.

A log/coal effect domestic gas fire has a tray 10 on which there is intended to be arranged incombustible pieces simulating coal or log lumps and a vermiculite, flame spreading, layer. Two gas burners 12 project through the floor 14 of the tray. The gas burners are generally similar in construction but the burner 12' at the front of the fire differs from the burner 12 at the rear of the fire in that it has adjustable air regulating means.

Each burner 12 comprises a cylindrical burner body 16 mounted on a block 18 in which gas passages 20 are formed, for example by drilling, the passage leading to the burner terminating in a distributor 22 which is threadably mounted in the block at the base of the burner body. Four equispaced circular circular holes 24 are formed in the body so that air may be admitted to the body to form with the gas from the distributor 22 a combustible gas/air mixture.To regulate the volume of air passing into the burner body 16 of the front burner 12' there is provided a regulator sleeve 26 which surrounds the body and is rotatable about the body, the sleeve having four holes 28 formed therethrough corresponding to the holes in the body, the dimension of the holes 24, 28 is so chosen that when the holes 28 in the sleeve 26 align with the holes 24 in the body 16 the maximum amount of air to provide efficient combustion is allowed to enter the body. Conversely, when the sleeve is rotated so that the holes are completely out of registry only 2% of the maximum amount of air for efficient combustion enters into the body.

An elongate operating lever 30 extending under the tray 10 is connected to the sleeve 26 so that the user may adjust the sleeve even when the fire is burning. The rear burner 12 has fixed size air openings 24 so that it has a constant supply of air thereto.

It will be realised, therefore, that with the front burner 12' the user can choose to have a highly thermally efficient aerated blue flame or a relatively thermally inefficient but visually pleasing yellow flame.

The burners are so designed that the flames they produce are distributed over a maximum area of the tray bottom so that flames appear at all parts in the display on the tray. To this end each burner body 16 has a cylindrical extension 32 fitted above the base 14 of the tray 10. At its outer end the extension 32 is provided with an outwardly and downwardly directed flange 34. A conical diffusing shield 36 is supported above the outlet of the burner body spaced from the flange 34. The external radius of the shield 36 is equal to the external radius of the flange 34 so that there is defined between the underface of the shield 36 and the top face of the flange 34 an annular passage 38 for the gas/air mixture.As a result of this passage 38 the gas/air mixture, which has been thoroughly mixed in the burner body 16, is distributed over 360 around the burner and across the tray floor 14.

Various modifications can be made without departing from the scope of the invention. For example, independently operable air regulating means can be provided also for the rear burner. The means for regulating the gas supply to all the burners may be a single means but it is preferable that the air regulating means for each burner is independently controllable.

The regulating means may take any suitable form, for example, they may comprise shutters slidable over the air inlet apertures or screw threaded collars movable to progressively mask off air inlet holes in the burner body. Additionally, the shape of the burner may alter from cylindrical but it is important in all instances that an outwardly extending downwardly directed deflector is fitted over the burner outlet. The flange at the end of the burner body may be dispensed with, although this will decrease the efficiency of flame spreading.

Claims (12)

1. A burner for gaseous fuel comprising a hollow elongate mixing chamber into which fuel and air are introduced and a diffusing shield arranged over and projecting laterally beyond the outlet from the chamber.

2. A burner as claimed in claim 1, in which the chamber is cylindrical and the diffusion shield is dome-shaped or conical.

3. A burner as claimed in claim 1 or claim 2, in which a flange is provided around the outlet from the chamber, the flange, together with the shield, defining an annular discharge passage directed generally radially outwardly from the chamber.

4. A burner as claimed in any one of claims 1 to 3, in which the chamber is provided with means for varying the gas/air mixture.

5. A burner as claimed in claim 4, in which the means for varying the gas/air mixture is an air inlet regulator.

6. A fire for gaseous materials including at least two burners, the burners each comprising a hollow elongate mixing chamber into which fuel and air are introduced and a diffusing shield arranged over and projecting laterally beyond the outlet from the chamber.

7. A fire as claimed in claim 6, in which each burner has independently operable air inlet means.

8. A fire as claimed in claim 6, in which only the burner which, in use, is at the front of the fire has air inlet regulating means.

9. A fire as claimed in claim 7, in which each burner comprises a cylindrical body having air inlet passages formed therein, the air regulating means comprising a cylindrical sleeve, with a corresponding number of air passages therethrough, arranged round the burner body and movable relative to the burner body to progressively open to mask off the air inlet passages in the body.

10. A fire as claimed in any one of claims 6 to 9, in which the burners are arranged in a tray adapted to support a simulated coal or log fire.

11. A burner substantially as hereinbefore described with reference to the accompanying drawing.

12. A fire substantially as hereinbefore described with reference to the accompanying drawing.