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(11) | EP 0 311 462 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Improvements relating to gas burners |
| (57) The present specification discloses a gas burner for use in a gas appliance. The
burner comprises a chamber (1,5) with a gas/air mix supply pipe (7) opening into the
chamber. A wall (5) of the chamber (1,5) is formed by a planar ceramic slab (5) with
a number of parallel very narrow elongate burner slots (11) formed therein, said slots
(11) being tapered from the inside wall of the slab (5) towards the outside surface
of the slab (5). |
[0002] In particular the present invention relates to a gas burner of the type which is conventionally located beneath a collection of simulated solid fuel elements in a simulated solid fuel effect gas fire, so that, in use, the flames from the burner lick around the simulated solid fuel elements to give the effect of a real fire eg. a real coal fire.
[0003] One known gas fire of the above type utilizes a burner having a series of holes in its upper surface, gas/air mix issuing from the holes and burning above said upper surface of the burner, with the flames licking around simulated solid fuel elements shaped in the form of lumps of coal. The flames produced by this burner are not particularly hot due to the combustion being less efficient than desired. The simulated solid fuel elements are thus constructed from a soft ceramic eg. compressed ceramic fibre, so that the fuel elements will glow under the heat of these particular flames, and provide the desired realism to the fire. However, due to the incomplete combustion there is a build up of carbon both on the soft ceramic fuel elements and on the fire infrastructure. The fire thus needs cleaning at regular intervals and due to the nature of the soft ceramic of the fuel elements being such as to promote carbon collection, the realism of the simulated solid fuel element is reduced, so much so, that after a period of use the fuel elements have to be replaced. Whilst this replacement is an easy though dirty operation, it is expensive to replace these soft ceramic fuel elements.
[0004] The aim of the present invention is to provide a gas burner for a simulated solid fuel gas fire, which burner provides for better combustion than the above prior art burner, by producing hotter and therefore cleaner flames, thus enabling hard ceramic fuel elements which are less susceptible to carbon collection, to be used, whilst retaining the required realism of the fire.
[0005] According to the present invention there is provided a gas burner for use in a gas appliance, said burner comprising a chamber with a gas/air mix supply pipe opening into said chamber, a wall of said chamber being provided with a number of elongate burner ports.
[0006] In a preferred embodiment of the present invention for use in a simulated solid fuel element gas fire, at least a portion of said wall of said chamber, is made from a high alumina ceramic with said elongate burner ports formed therein as a series of substantially parallel, or parallel, very narrow elongate slots. Alternatively said wall portion may be made of any suitable material, the prime criterion being that the material is extremely heat resistant. Preferably the high alumina ceramic wall portion is in the form of a planar slab of the ceramic with said elongate slots each extending over the majority of the width of the slab. Alternatively two or more such slots may be provided across the width of the slab. Each slot extends right through the ceramic slab and peferably each slot is tapered as it passes through the thickness of the slab, each slot being wider on the face of the slab defining an inside wall portion of the chamber than on the face of the slab defining an outside wall portion of the slab. Preferably the taper only extends for part of the slab thickness so that the slot has a constant dimension for the remainder of the thickness. In this way, a venturi is formed in the ceramic slab, thereby increasing the turbulence and velocity of gas/air mix and thereby enhancing the mixing of the gas and air, and optimising combustion. This mixing of the gas and air may be further enhanced by providing a diffuser net or baffle within the chamber between said gas/air mix supply pipe and said ceramic slab.
[0007] The above burner produces very hot blue flames which can envelop a simulated fuel bed with a minimum of carbon production. The fire is therefore cleaner. Further by virtue of the burner producing very hot flames the simulated fuel elements can be made of a h&rd ceramic so that soot collection is minimized whilst the hot flames still provide the desired glowing realism to the fire even with the hard ceramic simulated fuel elements. Maintenance-free life of the fire is thus optimised.
[0008] In a preferred embodiment of the present invention the chamber is formed as a generally rectangular dish with a gas/air mix supply pipe passing though the base of the dish, the ceramic slab closing the open top of the chamber. To secure the ceramic slab sealingly to the rim of the dish, a bezel is preferably pressed around and over both the edge of the slab and the rim of the dish or bolted thereto, preferably with a bead of ceramic cement between the ceramic slab and the bezel to reduce the possibility of the ceramic slab cracking during service. Alternatively the ceramic slab may be secured to the rim by a suitable adhesive e.g. a ceramic adhesive, or it may itself be bolted to the rim of the dish with a suitable gasket located between the slab and dish. Further the edge of the slab may be angled ie. chamfered, with the rim being bent over against the angled edge, or a casing with a lateral flange around which the rim can be bent, may be used to hold the slab in position. In each of the latter two alternatives, a suitable gasket or filter e.g. ceramic cement, may be used to seal the join between slab and rim.
[0009] For flame retention, a metal gauze may be secured over the slotted wall portion in any of the embodiments of the present invention.
[0010] Whilst the above preferred embodiment of the present invention utilizes one ceramic slab, two or more ceramic slabs may be sealingly located side-by-side in any one burner, as desired. In such a case one burner slot may be extended in the outer surface to facilitate cross lighting between burner slabs.
[0011] Whilst the burner of the present invention may be used with advantage in a simulated solid fuel element gas fire, such a burner may also be used with advantage in other gas appliances where a hot, clean flame is of use.
[0012] The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which:-
Fig. 1 is a perspective partially cutaway view of a preferred embodiment of the present invention;
Fig. 2 is a cross-sectional view of the embodiment of Fig. l;
Fig. 3 is a plan view of the ceramic slab of Figs. 1 and 2;
Fig. 4 is a cross-sectional view of the ceramic slab of Figs. 1,2, and 3, transverse to the cross-section of Fig. 2;
Fig. 5 is a cross-sectional view of another embodiment of the present invention;
Fig. 6 is a cross-sectional view of a further embodiment of the present invention;
Fig. 7 is a cross-sectional view of a still further embodiment of the present invention; and
Fig. 8 is a plan view of a still further embodiment of the present invention incorporating three ceramic slabs.
[0013] A preferred embodiment of the present invention is illustrated in Figs. 1 to 4 of the accomapnying drawings. This preferred embodiment comprises a generally rectangular, pressed, metal dish 1 with a rim 3, the open top of the dish 1 being closed by a rectangular slab 5 of high alumina ceramic material capable of withstanding high temperatures, the slab 5 being secured to the rim 3. A gas/air mix supply pipe 7 opens into the base of the dish 1 and, in use, supplies gas/air mix to the chamber defined by the dish 1 and the slab 5. To aid mixing of the gas and air a gauze diffuser screen 9 is provided in the chamber between the gas/air mix supply pipe 7 and the slab 5. Alternatively a suitable baffle can be located in the chamber to aid mixing.
[0014] The slab 5 is provided with a number of burner ports, each port being in the form of a very narrow slot 11 which extends virtually completely across the width of the ceramic slab 5 and completely through the slab 5, said slots 11 being parallel to each other and spaced apart from each other. In other embodiments (not illustrated) any arrangement of slots can be used, and a number of slots aligned with each other can replace each slot of the embodiments of Figs. 1 to 4. Each slot 11 in the illustrated preferred embodiment is tapered as at 13 from a wider configuration on the inside of the burner chamber to a narrower configuration as at 15, which extends with constant dimensions for part of the thickness of the slab 5 to open on the outside of the surface of the slab 5. This slot shape forms a venturi which, in use, increases the velocity and turbulence of the gas/air mix flowing therethrough and thereby optimises the homogeneous mixing of the gas/air mix to thus aid combustion.
[0015] The above narrow, elongate slots 11 enhance combustion and produce tall, very hot ie. blue, flames which, in a simulated solid fuel gas fire, can envelop all of the simulated fuel elements with a minimum of carbon being produced and deposited. Thus the fire is cleaner in operation than equivalent prior art fires. Further as the flames are very hot, hard ceramic material can be used for the simulated fuel elements, without detracting from the required realism of the fuel elements glowing. The use of hard ceramic simulated solid fuel elements has the advantage of resisting the effects of heat and the deposition of soot, as compared to the use of soft ceramic elements, and thus provides for a longer simulated fuel element life.
[0016] In the preferred embodiment of Figs. 1 to 4, the ceramic slab 5 is secured to the rim 3 by a bezel 17 which is pressed around and over both the rim 3 and the edge region of the ceramic slab 5, with a soft gasket 19 located between the slab 5 and the rim 3, and an amount of ceramic cement 20 filling the gap between the bezel 17 and the slab 5 to reduce the possibility of the slab 5 cracking during service. The slab 5 can alternatively be secured to the dish 1 in different ways, examples of which are shown in Figs. 5,6 and 7 of the accompanying drawings. In the embodiment of Fig. 5, the outer edge 21 of the ceramic slab 5 is angled ie. chamfered, and the rim 3 of the dish 1 is bent around this angled edge 21. Again a gasket 19 and a ceramic cement filler 20, are provided. In the embodiment of Fig. 6, the ceramic slab 5 has bores formed in its edge region and screws 23 are used to screw the slab 5 to the rim 3 - only one being in evidence in Fig. 6. Again a gasket 19 is used. In the embodiment of Fig. 7 a casing 25 engages around the outer edge region of the slab 5 with a ceramic cement 26 filling the gap between the slab 5 and the casing 25 to reduce the possibility of the slab 5 cracking during service, the casing 25 has a lateral flange 27 around which the rim 3 of the dish 1 is bent. A gauze diffuser 29 is used in the embodiment of Fig. 7, which diffuser is rigid enough to support the slab 5 in the casing 25, the diffuser being held at its outer edge between the rim 3 and the lateral flange 27 of the casing 25. Additionally, in the embodiment of Fig. 7 a gauze overlay 31 is secured over the slab 5 to aid flame retention ie. to hold the flames near to the surface of the slab 5. This overlay 31 can of course be used with any of the above embodiments of the present invention. As a further alternative to the above forms of attachment, the ceramic slab 5 can be secured to the rim 3 by any suitable ceramic or other adhesive.
[0017] Whilst the embodiment of Figs. 1 to 7 use a single ceramic slab 5, any number of such slabs (see Fig. 8) can be arranged in sealing juxtaposition in a single burner. In such a construction one of the slots 11 is extended as a groove 33, as shown in Figs. 3,4 and 8, to join with a corresponding groove 33 and slot 11, in the adjacent slab 5 to allow for cross lighting.
[0018] In all of the above described embodiments the dish 1 is closed by a ceramic slab 5 which is made of a high alumina ceramic material to withstand the high temperatures of operation without damage to the slot profiles resulting. However, any other suitable material can of course be used to form the slab 5.
1. A gas burner for use in a gas appliance, said burner comprising a chamber with
a gas/air mix supply pipe (7) opening into said chamber, characterised in that a wall
(5) of said chamber is provided with a number of elongate burner ports (11).
2. A gas burner as claimed in claim 1, wherein at least a porton of said wall (5)
of the chamber is made from a heat resistant material with said elongate burner ports
(11) formed therein as a series of substantially parallel, or parallel, very narrow
slots (11).
3. A gas burner as claimed in claim 2, wherein said heat resistant material is a high
alumina ceramic.
4. A gas burner as claimed in claim 3, wherein the ceramic wall portion is in the
form of a planar slab (5) of ceramic with said elongate slots (11) extending over
the majority of the width of the slab (5).
5. A gas burner as claimed in claim 3, wherein the ceramic wall portion (5) is in
the form of a planar slab of ceramic with two or more axially aligned slots (11) provided
across the width of the slab (5).
6. A gas burner as claimed in claim 4 or claim 5, wherein each slot (11) extends right
through the ceramic slab (5) and is tapered as it passes through the slab (5).
7. A gas burner as claimed in claim 6, wherein each slot (11) is wider (13) on the
face of the slab (5) defining an inside wall portion of the chamber than on the face
of the slab (5) defining an outside wall portion.
8. A gas burner as claimed in claim 6 or 7, wherein the taper (13) only extends for
part of the slab thickness, the slot (11) having a constant dimension for the remainder
(15) of the thickness.
9. A gas burner as claimed in any one of claims 4 to 8, wherein a diffuser net (9)
or baffle is provided within the chamber between the gas/air mix supply pipe (7) and
said ceramic slab (5).
10. A gas burner as claimed in any one of claims 4 to 9, wherein the chamber is formed
by a generally rectangular dish (1) with the gas/air mix pipe (7) passing through
the base of the dish (1), the ceramic slab (5) closing the top of the chamber.
11. A gas burner as claimed in claim 10, wherein a bezel (17) is passed around and
over the edge of the ceramic slab (5) and the rim (3) of the dish (1) to sealingly
secure the ceramic slab (5) to the dish (1).
12. A gas burner as claimed in claim 11, wherein ceramic cement (20) is located between
the periphery of the ceramic slab (5) and the bezel (17).
13. A gas burner as claimed in claim 10, wherein a bezel is bolted to the rim (3)
of the disk, over the ceramic slab (5).
14. A gas burner as claimed in claim 13, wherein ceramic cement (20) is located between
the periphery of the ceramic slab (5) and the bezel (17).
15. A gas burner as claimed in claim 10, wherein the ceramic slab (5) is bonded to
the rim (3) of the dish (1) using a suitable adhesive.
16. A gas burner as claimed in claim 10, wherin the ceramic slab (5) is bolted to
the rim (3) of the dish with a suitable gasket (19) therebetween.
17. A gas burner as claimed in claim 10, wherein the edge of the slab (5) is angled
and the rim (3) of the dish (1) is bent over the angled edge to secure the ceramic
slab (5) to the dish (1).
18. A gas burner as claimed in claim 10, wherein a casing (25) with a lateral flange
(27) engages over the ceramic slab (5) and the rim (3) of the dish (1) is bent around
the lateal flange (27) to secure the ceramic slab (5) in position on the dish (1).
19. A gas burner as claimed in any one of the preceding claims, wherein a metal gauge
(31) is secured over the elongate burner port wall portion (5).
20. A gas burner as claimed in claim 4, wherein two or more ceramic slabs (5), each
having elongate burner slots (11), are sealingly located in juxtaposition to eacha
other to define said wall portion.
21. A gas burner as claimed in claim 20, wherein a burner slot (11) in one ceramic
slab (5) connects with a burner slot (11) in a juxtaposed ceramic slab (5) by a groove
(33) provided in the surface of said slab (5).