GB2284475A - Solid fuel effect gas fire - Google Patents

Abstract

A solid fuel effect gas fire is provided with the aim of optimising the balance between combustion efficiency and solid fuel fire effect. To this end front and rear burner 10, 12 are provided with a spacing in between. A choke bar 52 is located in the region of the spacings to divide and restrict air flow to the gas flames. Gas outlet orifices are provided in concentration in areas between simulated solid fuel "pieces" 14 to provide concentration of gas flames in these areas. <IMAGE>

Description

SOLID FUEL EFFECT GAS FIRE The invention relates to a gas fire of the type which seeks to replicate the appearance of a solid fuel fire.

There is a basic tension in the design of a solidfuel (coal or log) effect gas fire, between providing maximum efficiency of gas combustion and producing a realistic solid fuel fire effect. Thus, if the gas/air mixture supplied to the burners is arranged to provide maximum combustion efficiency, it results in an almost all blue flame, which gives a poor solid fuel fire effect.

conversely, if the gas/air mixture is regulated to provide yellow flames, this produces a good solid fuel fire effect, but only at the expense of poor combustion efficiency.

The present invention broadly aims to tackle this basic tension with the goal of optimising the balance between combustion efficiency and solid fuel fire effect.

In this specification the term "primary air" denotes air which is mixed with gas prior to burning, and the term "secondary air" denotes air which can mix with the gas flame from the atmosphere surrounding the flame.

According to a first aspect of the present invention there is provided a solid fuel effect gas fire which has two gas burners arranged one behind the other with a spacing therebetween, and a plurality of simulated solid fuel "pieces" above the burners, wherein the supply of secondary air to at least one of the burners via the spacing is restricted.

By means of restriction of secondary air, an improved fuel effect may be obtained.

Preferably the supply of secondary air to both of the burners is restricted.

The supply of secondary air via the spacing could be restricted by providing only a narrow spacing between the burners, for example a spacing of 12mm or less, preferably 7mm or less. Preferably, however, an air choke is provided in the region of the spacing. This air choke can be made to be adjustable but is preferably fixed in position during manufacture. The air choke can conveniently be in the form of a bar extending across the spacing. Various shapes of bar are possible, which have the effect of dividing and restricting secondary air flow, by reducing the cross-sectional area of the flow pathways for secondary air, towards the burners. When the burners are set at the same height a flat bar set horizontally may suffice.However, it may be preferred for aesthetic reasons to set one of the burners slightly higher than the other burner, in which case an angle bar, conveniently an L-section bar, may be preferred. Whatever the form of bar used, suitably gaps of 1-5mm width are provided, for secondary air to flow through, to the burners.

The invention as defined above relates to restriction of secondary air supply via the spacing between the burners, to provide a good fuel effect at the heart of the gas fire. Additionally, to further enhance the effect, particularly at the margins, secondary air supply may be restricted around the periphery of the burner pair.

According to a second aspect of the invention in a solid fuel effect gas fire which has a plurality of simulated solid fuel "pieces" and a gas burner beneath them, the burner having a series of gas outlet orifices arranged so as to produce concentrations of gas flame in the areas between simulated solid fuel "pieces".

In one arrangement in accordance with the second aspect of the invention the gas burner has a row of orifices arranged width wise of the fire, but the spacing between the orifices varies, so that in regions corresponding to spaces between simulated solid fuel "pieces" the orifices are closer together than in the regions corresponding to the "pieces". This arrangement is particularly advantageous across the front of the fire.

It is generally desirable to provide a row of gas orifices across the front of the fire, but where the gas jets impinge on simulated solid fuel "pieces" the jets tend to be forced forward over the front edge of the fire which gives a poor solid fuel fire effect. However, if gas jets are concentrated in the spaces between the "pieces" then most of the gas flames pass upwardly through the spaces which gives a good simulation of a solid fuel fire. There is a secondary advantage of this concentration of gas jets in that in an area of concentration, there is greater competition for the available secondary air and hence, some tendency to produce yellow flames at the region of concentration. Yellow flames in a space between simulated solid fuel "pieces" produces an excellent solid fuel fire effect.

In a preferred arrangement, the burner has a row of gas orifices extending across the width of the fire adjacent to the front of the fire, the orifices being arranged in groups of two kinds alternating along the row, one kind corresponding to spaces between simulated solid fuel "pieces" having its orifices closer together than the orifices in the other kind which corresponds to the "pieces". In the preferred arrangement, the orifices in the groups corresponding to spaces are spaced from each other by a distance approximately half that of the spacing of the orifices in the groups corresponding to "pieces".

In a possible arrangement, the orifices of the other kind are omitted so that the front row of orifices comprises only discrete groups of closely spaced orifices at the locations corresponding to spaces in the simulated solid fuel "pieces".

In another preferred arrangement, the burner has front gas orifices arranged adjacent to the front of the fire space and a plurality of groups of rear gas orifices spaced to the rear of the front gas orifices and located in regions corresponding to spaces between front and rear (or intermediate) simulated solid fuel "pieces".

Preferably the spacing between adjacent gas orifices in the rear groups is similar to that of the orifices in the groups corresponding to spaces in the row of orifices across the front of the fire, ii.e. they are concentrated to provide a good solid fuel flame effect. Rear gas orifices may be provided at locations spaced by different distances from the front row of orifices, that is to say that in addition to the front row of orifices, there may be an intermediate set of orifice groups and to the rear of that, a rearmost set of orifice groups.

The first and second aspects of the invention defined above may be used together. The front burner may be as defined above with reference to the second aspect. The rear burner may have two sets of gas outlet orifices spaced forwardly and rearwardly of the rear burner.

Suitably at least one of these provides gas outlet orifices arranged to produce concentrations of gas flame in the areas between simulated solid fuel "pieces".

Suitably the rear set of gas outlet orifices is thus arranged. Suitably the front set is arranged so as to direct gas flames directly onto the underside of a series of "pieces" or, preferably, a long "piece" extending across the width of the fire, so as to cause glowing. This front set need not be arranged to produce any concentrations of gas flame, but can be evenly spaced across the width of the fire.

According to a third aspect of the invention a burner for a solid fuel effect gas fire comprises a plenum chamber having a gas inlet and a plurality of gas outlet orifices in an upper region of the plenum chamber, the plenum chamber comprising a lower part in the form of an open topped container and an upper part in the form of an open bottomed container which engages with the lower part to define the chamber, and which has a top in which the gas outlet orifices are formed.

This construction is very simple and enables access to the inside of the plenum chamber, because one part can be lifted from the other part, after removal of any securing means.

According to a fourth aspect of the invention, there is provided a solid fuel effect gas fire, having a front bar defined with and/or adapted to support solid fuel effect '1pieces", a raised bar spaced rearwardly therefrom, and elevated relative to the front bar, defined with and/or adapted to support solid fuel effect "pieces", and two side parts engaged with respective ends of the front bar and the raised bar.

Preferably, the ends of the front and raised bars are interlocked with the side parts.

Suitably, the raised bar is located directly above a set of gas outlet orifices.

Preferably the front and raised bars and the side parts are all of suitable solid fuel appearance and are of heat-absorbing material. Suitably they may be of a blackened ceramic material.

Preferably the fire also has a back plate of solid fuel appearance, so that the raised bar is located at an intermediate position of the fire.

Preferably separate "pieces" may be engaged on the front and/or raised bars. Rather than merely being rested where desired, as is conventional, it is desirable that their position be carefully determined, especially if the second aspect of the invention is to be used, relating to concentrations of gas flame, in conjunction with this fourth aspect. Suitably, therefore, interlock means is provided between these "pieces" and the front and/or raised bars. The interlock means may, for example, comprise one or more projections on one part, engageable with a corresponding recess or recesses, in the other.

"Pieces" having interlock means to engage other "pieces", as defined above, constitute a fifth aspect of the present invention.

The invention will now be further described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view and partial cross section through a first embodiment fuel effect gas fire showing only the features which are necessary to understand the invention; Figure 2 is a front view of the fire shown in Figure 1; Figure 3 is a plan view of a bottom part of the fire shown in Figure 1, indicating the location of certain simulated solid fuel "pieces"; Figure 4 is a cross section to a larger scale through a front burner; Figure 5 is a detail end view showing an alternative position of a choke; Figure 6 is a side view and partial cross section through a second embodiment of fuel effect gas fire showing only certain key features;; Figure 7 is a plan view of the fire shown in Figure 6, with simulated solid fuel "pieces" removed so as to show the arrangement of gas outlet orifices in the upper surfaces of the two gas burners; Figure 8 is a perspective view of a side part of the fire; Figure 9 is a side elevation of the side part; Figure 10 is a front elevation of a back plate of the same fire; Figure 11 is a front elevation of a raised bar used within the same fire; Figure 12 is a separate fuel effect "piece" engageable on the bar shown in Figure 11; Figure 13 is a front elevation of a front bar of the same fire; and Figure 14 is a separate "piece" which may be engageable on the front bar shown in Figure 13.

The fires illustrated in the drawings are intended to fit in the conventional domestic fire space which narrows towards the rear. Each fire has a framework which is generally not illustrated.

With reference now to the embodiments of Figures 1 to 5, in its essentials, the fire comprises a front burner 10 and a rear burner 12 above which are located an assembly of simulated coal pieces 14, which form a stack such as would be formed in a real coal fire. Gas flames from the burners 10 and 12 pass upwardly around and between the pieces 14, in some places impinging on and being diverted by the pieces, to produce the appearance of a real coal fire. The heat given off by the gas flames provides the heat for room heating. Since real coal flames are usually yellow, it is necessary to regulate the air supply to the gas flames to produce enough yellow flames to provide the solid fuel fire effect.

The front burner 10 comprises a sheet steel plenum chamber 16 and a gas supply tube 22. The plenum chamber is constituted by an outer part 18 and an inner part 20 (see Figure 4). As shown in Figure 3, the plenum chamber is trapezoidal in plan, this shape conforming to the shape of the front part of the fire space in which the fire is located. The outer part 18 is in the form of a deep tray, that is to say, it is open at the top. The inner part 16 is an inverted deep tray (i.e. it is open at the bottom) and comprises a top 24 and a skirt 26.

Located in the bottom of the outer part 18 is a ceramic gasket 28 in the shape of a rectangular pad which fills the bottom of the outer part, there being a central hole in the pad registering with the bore of the gas pipe 22. The bottom edges of the skirt 26 rest on this gasket and form a seal with it. The construction of the burner 10 is particularly convenient, because access can be had to the interior by simply lifting the inner part 16 out of the outer part.

The gas inlet 22 is connected to a gas supply with a manually operable flow control (not shown) so that gas can flow up into the chamber 16. A primary air inlet is indicated diagrammatically at 30 in Figure 1. This air inlet is adjustable, but is intended to be preset when fitting the fire to restrict the supply of primary air to something less than the ideal required for maximum combustion efficiency, in order to ensure that some yellow flames are produced by the burner.

A front row of simulated coal pieces 14a is provided on the top face of the plenum chamber 16, and, as indicated in Figures 2 and 3, these pieces 14a are all of the same order of size and they are approximately evenly spaced across the width of the burner 10. The pieces 14a are made of moulded ceramic material and they are formed into different shapes to simulate five pieces of coal, including areas simulating incandescent coal. The techniques for the production of such ceramic simulated coal pieces are known. An important feature is that the pieces 14a are secured to the top plate of the front burner 10, so that they cannot be displaced.

A row of small holes 32 is formed through the top plate 24 of the inner part 16 of the burner 10 and these provide gas outlet orifices from the burner. When lit, each of the orifices 32 produces a gas flame, as indicated at 34 in Figure 1. The row of holes 32 extends across the width of the burner 10, but it will be observed that the holes are not evenly spaced. At four locations indicated as 32b and corresponding to spaces between the simulated coal pieces 14a, the holes are very close together, whereas at the remaining five locations, corresponding to the locations of the pieces 14a, they are more widely spaced. In a specific example, the spacing of the holes in the clusters at 32b is only half that in the remaining locations. This arrangement assures that there is a concentration of gas flames at the spaces between the simulated coal pieces, which produces the desired effect of flames occurring at the junction between pieces of coal. Furthermore, because there is a concentration of flames at each cluster 32b, those flames have less chance of taking in secondary air than have the flames from the more widely spaced orifices and hence, there is a greater tendency for each cluster of flames to have yellow portions - again adding to the burning coal effect.

Reverting now to Figure 3, it will be seen that a second set of holes 36 is formed in the top plate 24 adjacent to the rear edge of the burner 10, so as to provide a second set of gas outlet orifices. The holes 36 are in discrete groups spaced from each other across the width of the burner and each group corresponds to the location of one of the simulated coal pieces 14a. The flames 38 from these groups of orifices play on the rear edges of the pieces 14a as shown in Figure 1.

It will be appreciated therefore, that by a predetermined relationship between the pattern of the holes 32 and 36, and the locations of the fixed simulated coal pieces 14a, a very effective coal fire flame simulation can be achieved. In the example, the pattern of the holes is provided by in the one case discrete groups of holes (as at 36) or by varying the spacing of the holes in a row (as at 32).

The rear burner 12 is constructed in the same way as the front burner 10. It has two rows of gas outlet orifices, one near to its front edge and one near to its rear edge and these holes may be arranged in the same way as those of the front burner, so as to concentrate the flames in areas which will give a good solid fuel fire effect. The overall width of the rear burner is in any case narrower than that of the front burner because of the narrowing of the fire towards the rear, but as seen in plan, the rear burner 12 is rectangular.

A hollow ceramic support bar 40 pointed at its lower end bridges between two side structural elements of the fire (not shown) and the orientation of the bar 40 is such that it provides a flat top surface. The bar 40 is positioned so that it divides the flames from the front and rear orifices of the burner 12. Support brackets 42 are welded to the rear face of a rear wall 44 of the fire frame one near to each end, and a ceramic heat reflective slab 46 rests on the brackets 42. This slab 46 extends across the whole width of the fire at the rear, and it forms an effective rear wall of the fire. At its upper end, the ceramic slab 46 is formed with a series of four simulated coal pieces 14d, similar to the ceramic simulated coal pieces 14a, excepting that as they are joined at the rear to the slab 46, only the front part of the simulation is required.As with the simulated coal pieces 14a, the pieces 14d may have portions simulating incandescent areas of a real coal fire. Flames 48 from the rear row of orifices in the rear burner 12 pass up the front of the slab 46, causing that slab to become incandescent, and at their upper ends, the flames impinge on the undersides of the simulated coal pieces 14d.

A plate 43 bridges and is welded to the brackets 42, so that there is a restricted air ingress opening at the rear of the fire between the burner 12 and the plate 43.

Two sets of simulated coal pieces 14b and 14c are also provided, but these are made of moulded resin impregnated with glass fibres. The pieces 14k of which there are four and 14c of which there are five, are completely loose. As indicated in Figure 1, five simulated coal pieces 14c rest on the flat upper surface of the support bar 40, and at their rear sides, they rest against the front of the ceramic slab 46. When these pieces 14c have been placed in this position, it is then possible to rest the four pieces 14b in the spaces between the coal pieces 14a and 14c, the pieces 14b being supported only on these other pieces 14a and 14c.This provides a very effective way of creating a simulated coal fire, and moreover, if required, the pieces 14b and 14c which of course are of different shapes, can be removed and rearranged, to give the effect of a fire of differing shapes.

The flames 50 from the gas outlet orifices across the front of the rear burner 12 pass upwardly through the spaces between the simulated coal pieces 14b and 14c, whilst the flames 38 from the groups of orifices at the rear of the front burner 10, pass upwardly through the spaces between the simulated coal pieces 14a and 14b.

Thus, a very good overall coal effect fire is produced with flames passing through the spaces between the four rows of simulated coal pieces 14a, 14b, 14c and 14d.

A steel angle iron 52 extends across the width of the fire at the position between the front and rear burners, and provides a choke for secondary air as will hereinafter appear. Spaced apart metal pads 54 are welded to the underside of the bar 52, and similarly, spaced apart metal pads 56 are welded to the rear of the outer part 18 of the front burner 10. Figure 1 illustrates the situation, where the bar 52 is laid over the space between the front and rear burners, with the pads 54 resting on the front edge of the rear burner, and the front face of the bar 52 resting on the top corners of the pads 56. In this position, secondary air from underneath the fire is able to flow through the narrow spaces defined by the thickness of the pads 54 and 56.That secondary air which passes up the front of the bar 52 is able to reach the flames 38 associated with the front burner, and that which passes through the spaces between the pads 54, is able to reach the flames 50 from the rear burner 12.

Referring now to Figure 5, the choke bar 52 is shown in an alternative position, where it rests against the top front edge of the front burner 12, and therefore completely closes access for secondary air from underneath the fire to the flames 50. On the other hand, secondary air can still flow through the spaces between the pads 56 to the flames 38. This illustrates, that by initial positioning of the choke bar 52, when the fire is being fitted, it is possible to change the distribution of the secondary air between the flames 38 and 50, and this can be used to enhance the coal fire effect as required by the particular spacing of the simulated coal pieces.

The embodiment of Figures 6 to 14 will now be described, primarily with reference to the differences from the embodiment of Figures 1 to 5.

In the second embodiment, the front burner 110 is set somewhat higher than the rear burner 112. The bar 152, which serves as the choke, has its position fixed in manufacture, being held there by securement means, not shown, and is set in the region of the spacing between the burners, such that one flange is parallel to, and spaced slightly back from, the rear wall of the front burner and the other flange, which is substantially the narrower flange, is parallel to, partially overlapping and slightly above, the top surface of the rear burner. The gaps thus defined by the bar 152 and the burners are normally set in the range 2-4mm.

The construction of the plenum chambers is different to that in the first embodiment. The lower tray 118 fits closely within the upper tray 116. The lower tray has a rim which is folded down at 160 inwardly of the tray. The skirt 162 around the upper tray, which is much narrower than the corresponding skirt in the first embodiment, engages over the folded-over rim of the lower tray, with a ceramic sealing band 164 engaged therebetween.

The trays of the respective plenum boxes 110, 116 are secured together by bolts and nuts, or like fixings, unlike those of the first embodiment.

It will be seen from Figure 7 that the arrangement of gas outlet orifices is somewhat different to that in the first embodiment. It will be seen that both sets of gas outlet orifices of the front burner, and the rear set of the rear burner, provide concentrations, as described previously. However, the front set of the rear burner comprises a relatively small number of evenly spaced single gas outlet orifices. The reason for this will be described later.

The simulated coal pieces are substantially different from those in the first embodiment.

It will be seen from Figure 13 that the front row 114a comprises five pieces, but these are moulded on a single bar, having a flat base 165 which rests on the upper surface on the front burner, adjacent its front edge.

The part corresponding to the ceramic bar 40 in the first embodiment, is the moulded part 140 shown in Figure 11. As will be seen in this Figure, the front face of this bar 140 is fluted and, like the other parts, of blackened ceramic, in order to look unobtrusive in the assembled fire. In the assembled fire the bar 140 is spaced from the front bar 114a, and elevated relative to it, being raised above the rear burner 112, by means of the side parts 116, one of which is shown in Figures 8 and 9 and both of which are shown in plan in Figure 7.

As seen in Figure 7, the side plates are mirror images of each other. Each side part has a wall portion 168 to rest upon the appropriate lateral edge region of the rear burner, and a wall portion 170 set at an angle to the wall portion 168, to rest upon the appropriate lateral edge region of the front burner. It should be noted that the wall portion 168 is formed with a recess 172 open upwardly, and that wall portion 170 is formed with a recess 174, open downwardly. The recesses 172 of the respective side parts receive end projections 176 of the bar 140, so that the bar 140 is located precisely in the required location. The recesses 174 receive projections formed at the ends of the front bar 114a. The wall portion 168 has a step 169 in its lower front corner, to abut, when assembled, the respective rear corner of the front burner.

Thus, the front bar 114a, the raised bar 140 and the side parts form an interlocked grid, on which further pieces can be mounted.

It will be noted that the bar 140 has five evenly spaced upper projections 180. These projections are triangular in plan. Upon each of these is engaged, in use, a discrete fuel effect "piece" 182, shown in Figure 12, each such "piece" having a correspondingly shaped recess 184 formed on its underside, for positive location on the bar 140.

The pieces which are integral with the front bar 114a have upwardly-facing cuboid shaped recesses formed in their upper rearward corners. Four discrete pieces 186 shown in Figure 14 can be mounted, one across each gap between these pieces of the front bar 114a. To achieve this each of the four discrete pieces has a pair of projections 188 for engagement with a pair of recesses of adjacent pieces of the front bar 114a.

The final blackened part is a back plate 146, shown in Figure 10, in the form of a ceramics slab. This back plate itself is formed with four pieces 114d in its upper region. Unlike the slab 46 of the first embodiment, it is not secured to a back bracket. Rather, the rear portion of the fire has a metal back plate 192, and a small gap 194 is provided between the back plate and the rear edge of the rear burner. The slab 146 can be slid into position and is entrapped between the back plate 192 and the rear faces of side parts 166. It should be noted that the back plate is moulded with two lugs 196 one at each end of its lower edge, to leave a gap for the flow of secondary air to the rear set of gas outlet orifices of the rear burner. Moreover the central lower edge is somewhat cut away at 198, to increase secondary air flow to the centre of the fire.

It should be noted that the front set of orifices of the rear burner, in this embodiment, those which are single and evenly spaced, are located directly beneath the raised bar 140. They play directly onto the lower edge, and are intended to make this bar extremely hot, so that it provides an orange glow in the centre of the fire.

Claims (7)

1. A solid fuel effect gas fire which has two gas burners arranged one behind the other with a spacing therebetween, and a plurality of simulated solid fuel "pieces" above the burners, wherein the supply of secondary air to at least one of the burners via the spacing is restricted.

2. A fire as claimed in Claim 1, wherein the supply of air to both of the burners by the spacing is restricted.

3. A fire as claimed in Claim 2, wherein an air choke is provided in the region of the spacing.

4. A fire as claimed in Claim 3, wherein the air choke is a L-section bar.

5. A solid fuel effect gas fire which has a plurality of simulated solid fuel "pieces" and a gas burner beneath them, the burner having a series of gas outlet orifices arranged so as to produce concentrations of gas flame in the areas between simulated solid fuel "pieces".

6. A fire as claimed in Claim 5, wherein the gas burner has a row of orifices arranged width wise of the fire, but the spacing between the orifices varies, so that in regions corresponding to spaces between simulated solid fuel "pieces" the orifices are closer together than in the regions corresponding to the "pieces".

7. A solid fuel effect gas fire substantially as hereinbefore described with reference to the accompanying drawings.