Note: Descriptions are shown in the official language in which they were submitted.
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GAS BURNER FOR FIREPLACE
The present invention relates to fireplaces, and in
particular to a gas burner for a fireplace that provides
variations in the height and appearance of the flame in
the fireplace. In particular, the gas burner provides
combustible gas mixed with so-called primary air in two
different ratios of air:gas in order to provide the
variations in the flame in the fireplace.
Fireplaces with a prefabricated combustion chamber
for combustion of natural, propane or other such gases
are known. These fireplaces may be either inserted into
existing conventional masonry fireplaces or may be
installed and subsequently framed within the structure of
the building, with the combustion chamber vented into a
flue or chimney. A facade is installed so that the
exterior has visual appeal. The heating and visual
effects of the fireplace per se are provided by means of
a gas burner which simulates a conventional wood fire,
with the combustion conditions being carefully
controlled.
In fireplaces in which combustion products from the
burner are conveyed to the flue, a supply of air may be
provided to the flue to ensure that there is a constant
flow of combustion products from the combustion chamber
into the flue and also to dilute the combustion products
to reduce condensation in the flue. Air may also flow
into the combustion chamber. Fireplaces for the burning
of combustible gases, with combustion products being
conveyed from the burner to the flue, are described in
U.S. 5,313,932 of H.H. Rieger and C. Adamson.
Other types of fireplaces are known as vent-free
appliances, in which case the fireplace is operated
without the need to vent combustion gases.
In the combustion chamber of the fireplace, it is
common to simulate a wood fire by placing logs made from
a ceramic material above the gas burner. The logs are
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normally painted to resemble a log, and are arranged to
simulate logs on a wood fire. The logs are located on a
ceramic grid through which combustible gas admixed with
air passes and is ignited. The resultant flame tends to
heat the ceramic log material to a red glow, thereby
causing the visual effect of a wood fire. Fireplaces
typically use a flame that is relatively static
throughout its length and does not vary significantly
with time.
In the present application, the flames of the
fireplace may be described as a blue flame or a yellow
flame, which describes the visual nature of the flame.
A burner assembly has now been found that is capable
of providing both a blue flame for creating sufficient
heat to cause the ceramic grid, ceramic logs and media to
glow red, as well as a yellow flame that varies with
time. Media are small ceramic fragments which glow red
and give the appearance of embers in the fire.
Accordingly, an aspect of the present invention
provides a gas burner for a fireplace, comprising:
an elongated burner housing having a length and a
width, said elongated burner housing having a grid of
openings in a surface thereof and a gas distribution
plate located underneath and adjacent said grid, said
grid being formed from heat resistant material, said
elongated burner housing having a burner box and a
chamber arranged therein along a length of the housing,
said elongated burner housing also having a first burner
assembly and a second burner assembly in a side-by-side
relationship therein, said chamber having a perforated
plate forming an upper surface thereof, each of the first
and second burner assemblies having a gas mixing area
wits an inlet for air and combustible gas and air flow
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controllers for controlling the ratio of air to gas in
the first burner assembly lower than the ratio of air to
gas in the second burner assembly, said first burner
assembly communicating with said chamber and said second
burner assembly communicating with said burner box such
that (i) air and gas is adapted to pass from said second
burner assembly into the burner box and through said gas
distribution plate and (ii) air and gas is adapted to
pass from said first burner assembly through said chamber
and through both said perforated plate and said gas
distribution plate.
In a preferred embodiment of the gas burner of the
present invention, the air flow controller is in the form
of an adjustable opening for inlet of air, especially in
the form of an adjustable shutter, and said air is
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primary air for the gas burner.
In another embodiment, the second burner assembly
provides a greater amount of primary air for combustion
of said gases at said orifices than said first burner
assembly.
In a further embodiment, the first burner assembly
provides a yellow flame and the second burner assembly
provides a blue flame.
In yet another embodiment, the air flow controller
of the first burner assembly controls the ratio of
primary air and gas such that secondary air from exterior
to said burner assembly is required for complete
combustion of the gas, the resultant flame being a yellow
flame.
In a still further embodiment, the grid is formed of
ceramic.
In yet another embodiment, the perforations in the
distribution plate are larger for the second burner
assembly.
The present invention is illustrated by the
embodiments shown in the drawings, in which:
Fig. 1A is a schematic representation of a fireplace
of the prior art;
Fig. 1B is a schematic representation of a fireplace
of the present invention;
Fig. 2 is a schematic representation of an exploded
view of a burner assembly of the present invention;
Fig. 3 is a schematic representation of a plan view
of the gas burner;
Fig. 4 is a schematic representation of the burner
box perforated plate;
Fig. 5 is a schematic representation of the gas
distribution plate, on its edge;
Fig. 6 is a schematic representation of a plan view
of the gas distribution plate;
Fig. 7 is a schematic representation of an alternate
embodiment of the burner assembly, in exploded view; and
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Fig. 8 is a schematic representation of a further
embodiment of the present invention.
Referring to Figure 1A, which illustrates prior art,
fireplace 1 has a facade 2 with air vents 3. Facade 2
surrounds glass panels or doors on the front of
combustion chamber 4. Combustion chamber 4 contains
ceramic grid 5 with logs 6 thereon, logs 6 being formed
of a ceramic material, and normally painted to resemble
the visual appearance of a wooden log. A blue flame 7 is
shown as extending a short distance above the ceramic
grid 5, with a yellow flame 8 extending above the level
of blue flame 7. In the representation of the prior art,
the yellow flame is of a substantially even height across
the width of the ceramic grid, and exhibits only a minor
amount of variation with time.
In Figure 1B, fireplace 1 is the same as shown in
Figure 1A, with blue flame 7 extending for a short
distance above ceramic grid 5. However, in the
embodiment of the invention illustrated in Fig. 1B,
yellow flame 8 extends substantially above blue flame 7,
and furthermore is not substantially of the same height
across the width. In addition, as discussed below, the
height of the yellow flame varies in a random pattern,
and more closely simulates a natural wood fire.
Figure 2 shows a gas burner of the present invention
in an exploded view. Gas burner 10 has burner housing 11
into which fits burner box 12. Burner box 12 is
elongated and fits in the front side of burner housing
11, as viewed in the drawing and which is the front of
the gas burner as viewed in use. Burner box 12 extends
for a substantial part of the length of the burner
housing 11, as illustrated below, but permits gas and air
to flow out the top thereof, as also discussed below.
Perforated plate 13 fits into burner housing 11 in a
side-by-side relationship with burner box 12. Gas
distribution plate 14 fits over burner housing 11, and
ceramic grid 15 is placed on the top of gas distribution
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plate 14, to form the exterior surface of burner housing
11. First bracket 18 and second bracket 19 fit on the
exterior of burner housing 11 to retain ceramic grid 15
in position. First burner assembly 16 and second burner
5 assembly 17 extend into burner housing 11 in the
embodiment shown in Figure 2, but in the preferred
embodiment of Figure 7 discussed below first elongated
tube 16 does not extend into burner housing 11.
In the embodiment illustrated in Figure 2, first
burner assembly 16 has air flow controller 20B on the end
thereof which fits on end 21 of tube 23 that forms first
burner assembly 16. The preferred air flow controller is
an air shutter, which is referred to herein as the
primary air shutter. Primary air is the air admixed with
the gas in the burner assembly, in contrast with
secondary air which is air from exterior to the burner
housing and which may be required for complete combustion
of gas that has passed through the grid, as described
herein. Thus, the air flow controller is particularly in
the form of an adjustable air opening, which may be
referred to as an adjustable primary air opening, and is
preferably in the form of an adjustable primary air
shutter. Other adjustable air openings are known.
The present invention will be particularly described
herein with respect to the preferred embodiment in which
the primary air flow controller is in the form of a
primary air shutter. The primary air shutter of first
burner assembly 16, and in second burner assembly 17
discussed below, is intended to permit and control the
flow of primary air into the elongated tube, and
especially the ratio of primary air: combustible gas being
fed to the burner. As noted above, an alternate method is
described with respect to Figure 7.
Second burner assembly 17 has primary air shutter
20A on the end thereof which fits on end 21 of tube 24
that forms second burner assembly 17. Primary air
shutter 20A and tube end 21 are adapted to control the
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flow of air through the primary air shutter and into
second elongated burner assembly 17, as well as adjusting
the flow of air into second burner assembly 17 so as to
provide a predetermined ratio of primary air:gas. As
discussed herein, the ratio of primary air: combustible
gas is different in the two burner assemblies.
Plate 22, which has holes therein for accommodating
first and second burner assemblies 16 and 17, fits on the
end of burner housing 11 to form a gas-tight seal.
Tube 23 of first burner assembly 16 is shown as
being shorter than the length of the corresponding tube
24 of second burner assembly 17, as more clearly shown in
Fig. 3, and in preferred embodiments does not extend into
burner housing 11, as discussed with respect to Figure 7.
Tube 24 extends into burner box 12. Tube 24 passes
through hole (opening) 25 located in the end of burner
box 12. It is understood that burner box 12 occupies a
smaller portion of burner housing 11 than does the region
accommodating first burner assembly 16. This has the
consequence that the ratio of flow of primary air and gas
from first burner assembly to ceramic grid 15 is less
than the rate of flow of primary air and gas from second
burner assembly 17. As discussed below, the slower rate
of flow from first burner assembly 16 facilitates
variations in the flame pattern therefrom in the so-
called yellow flame.
Burner box 12, with second assembly 17 therein is
further separated from the first burner assembly by means
of perforated plate 13. Perforated plate 13 has upper
panel 26 with a plurality of openings 27 therein, as
discussed below, and side panel 28 which extends downward
and is in a fitting relationship with burner box 12. Gas
can flow around the two ends of the side panel 28 and
into the area of burner box 12. This permits gas to flow
into and through the perforated holes on gas distribution
plate 14 to provide a yellow flame in that area of the
plate.
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Gas distribution plate 14 has side panel 29 thereon
which mates with the corresponding side of burner housing
11. In addition, gas distribution plate 14 has upper
panel 30 which has a plurality of openings, orifices and
slots therein, as discussed below. It will be noted that
primary air and gas flow from the first burner assembly
through both perforated plate 13 and gas distribution
plate 14, whereas primary air and gas from second burner
assembly 17 must only pass through gas distribution plate
14. In various embodiments of the invention, gas
distribution plate 14 may be of symmetrical construction
or not of symmetrical construction. Ceramic grid 15 has
a honeycomb-type distribution of openings therein, not
shown, through which mixtures of combustible gas and
primary air will flow, and be ignited on the upper
surface or otherwise above ceramic grid 15.
Figure 3 shows a plan view of the gas burner of the
present invention. The gas burner has burner housing 11
into which extend first burner assembly 16 and second
burner assembly 17, respectively. Exterior to housing 11
are primary air shutters (air openings) 20A and 20B, as
discussed above. In the embodiment of Figure 3, tube 23
of first burner assembly 16 extends a short distance into
burner housing 11, but in other preferred embodiments,
assembly 16 does not extend into burner housing 11. Tube
24 of second burner assembly 17 extends for a substantial
length of burner housing 11, but it does not extend to
the end of burner box 12. The view of Figure 3 shows
openings 35 and 36 of gas distribution plate 14, which
are above second burner assembly 17. While such openings
might be referred to as orifices, the latter term is
typically used with respect to control of flow of gas.
In addition the view shows the plurality of slots 37 of
gas distribution plate 14 that are above first burner
assembly 16.
Figure 4 shows perforated plate 13. Perforated
plate 13 has upper panel 26 with openings 27 therein, and
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side panel 28 that extends downwardly, and which would be
in a side-by-side relationship with burner box 12. Upper
panel 26 has an array of openings which may or may not be
in a linear configuration, indicated by 38, on opposed
ends of the front edge of upper panel 26. As illustrated
the array of openings are a pattern of openings of
varying sizes. Upper panel 26 additionally has a
centrally located set of openings that are in a pattern
that resembles the shape of the letter W. It is to be
understood, however, that the shape of a letter W is only
one example of the pattern that may be used, and that
other patterns of openings may be used, particularly
depending on the arrangement of logs and the distribution
of flames to be achieved. It is further understood that
the pattern of openings on perforated plate 13 and on
upper panel 30, discussed below, would align with the
various openings in gas distribution plate 14.
Intermediate between the array of openings 38 and the set
of openings 39 are a series of scattered openings
generally indicated by 40.
It is to be understood that the pattern of openings
may be varied particularly depending on the visual
effects required of the fire, and the arrangement of logs
that are placed on top of ceramic grid 15. However, it
is generally preferred to have a series of openings that
would be along the front edge of the burner assembly, as
viewed by a person watching the fire, and a set of
openings that are more centrally located, and which would
normally be located under a central arrangement of
ceramic logs on ceramic grid 15.
Figure 5 shows gas distribution plate 14, in an edge
view with upper panel 30 being shown in a vertical
orientation. Gas distribution plate 14 has a plurality
of slots that generally correspond in shape and location
to the openings in perforated plate 13 which is located
immediately underneath gas distribution plate 14. Thus,
gas distribution plate 14 has slots on the front edge
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thereof, indicated by 38A, which may be linear slots, a
series of slots generally in the shape of the letter W
(in the embodiment illustrated) in a central location,
indicated by 39A, and additional slots in an intermediate
area, indicated by 40A. In addition, gas distribution
plate 14 has a large centrally located opening, 36A,
which as illustrated is a truncated triangle, but other
shapes may be used, with a row of openings on each end
thereof indicated by 35A. It is to be understood that
the openings indicated by 35A, 38A, 39A and 40A are
located generally above first burner assembly 16, and
that opening 36A is located generally above second burner
assembly 17.
Figure 6 shows gas distribution plate 14 in plan
view, with the openings and slot as discussed above. It
will be noted that the openings 35A closely related to
opening 36A are shown as being of two different sizes.
As discussed above, the openings and slots shown in
Figure 6 may be varied in shape size and location.
When the gas burner is assembled, it is understood
that the various components are attached in a gas tight
manner in accordance with acceptable manufacturing
processes for gas burners. The primary air shutters, 20A
and 20B, would normally be set at the time of manufacture
in accordance with predetermined specifications, but
could be adjustable.
Second burner assembly 17 may be referred to as a
burner, as this burner is intended to provide the red
glow to the ceramic logs and ceramic grid 15 in region of
the fire that would be the front as viewed. Primary air
shutter 20A is set to provide a mixture of combustible
gas and primary air fed to the burner that has a high
ratio of primary air:combustible gas, so that when the
gas ignites on the surface of the ceramic grid, the flame
is short and blue. The flame is short in height which in
turn heats the ceramic burner material to a temperature
at which it glows a bright red. The pattern in which the
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ceramic grid glows is the same as the large geometric
pattern 36A on the gas distribution plate 14. High
temperature materials are generally used to manufacture
logs that are placed on and around the radiant portion of
5 this grid in order to simulate an ember bed effect of a
wood fire, with ceramic materials being preferred. The
gas and primary air mixture flows through gas
distribution plate 14 before passing through the
honeycomb-type structure of ceramic grid 15.
10 Combustible gas and primary air are mixed in the
same way as for the burner assembly 17, but a lower ratio
of primary air to combustible gas is used. This may also
be accomplished using the preferred embodiment of Figure
7, which uses a different method of mixing primary air
and gas as is described for burner assembly 17. The
mixture of primary air and gas travels through the holes
of the rear perforated channels, and through the slots in
the gas distribution plate, and then through the
corresponding holes of the honeycomb-type structure of
the ceramic grid. As a result of the lower ratio of
primary air to combustible gas, the flames that are
obtained are much taller and normally require secondary
air from within the combustion chamber in order to
complete combustion of the gas. This causes the flames
to burn with more yellow colour and thus to more closely
simulate that of a wood fire. In addition, the size of
the burner housing 11 is such that the pressure in the
burner housing 11 continuously changes by small amounts
due to movement of the premixed primary air and gas
within the burner housing 11. This causes fluctuations
in the flow of the mixture of gas and primary air through
the distribution holes in the gas distribution plate and
causes the flame to flicker and dance in the manner of a
natural wood fire.
In preferred embodiments of the present invention,
the gas burner has a first burner assembly that provides
less primary air for combustion of the gas at the
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orifices, than the second burner assembly. Preferably,
the first burner assembly provides a yellow flame and the
second burner assembly provides a blue flame.
Figure 7 shows an alternate, and preferred,
embodiment of the burner assembly, in exploded view.
Burner housing 51 has two inlets 52 and 53. Inlet 52
accommodates the second elongated burner assembly,
generally indicated by 54, which has elongated tube 55
that passes through plate 56 that fits on the end of
burner housing 51 to form a gas tight seal thereon.
Elongated tube 55 is also connected to primary air
shutter 57, which as discussed herein has an adjustable
air opening therein for control of the ratio of primary
air to combustible gas.
Inlet 53 accommodates the first burner assembly.
Inlet 53 is in the form of a opening 58 with a plurality
of openings 59 in the back side and bottom of burner
housing 51 in close proximity to opening 58. Opening 58
is for inlet of combustible gas into burner housing 51,
whereas openings 59 are for inlet of primary air. The
inlet of primary air is controlled by a shutter plate 64
located outside burner housing 51 at openings 59.
The inlet of gas to the burner assemblies is
controlled by gas valve 60 which is connected to gas
manifold 61. Gas passes from gas manifold 61 through gas
orifices 62 and 63 into the respective burner assemblies.
The ratio of primary air to combustible gas is
controlled by primary air shutter 57 and a shutter plate
64 located outside burner housing 51. Shutter plate 64
is intended to slide on burner housing 51, so that the
opening therein adjustably covers openings 59 in burner
housing 51.
In the embodiment illustrated in Fig. 8, first
burner assembly 116 has air flow controller 121A on the
end thereof which fits onto tube 123, to form first
burner assembly 116. Similarly, second burner assembly
117 has air flow controller 121B on the end thereof which
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fits onto tube 124, to form second burner assembly 117.
Burner box 120 is located within burner housing 110.
Both first burner assembly 116 and second burner assembly
117 extend into burner housing 110, but first burner
assembly 116 extends into burner box 120 through opening
125 thereof. Thus, while both burner assemblies are
within burner housing 110, only first burner assembly 116
is within burner box 120.
Perforated plate 130 fits over burner housing 110.
It will be noted that perforated plate 130 has a
different pattern of openings than the corresponding
plate illustrated in Fig. 2, thereby showing an
alternative embodiment of the openings that may be
embodied in the perforated plate. Gas distribution plate
140 fits on perforated plate 130, and has a similar
pattern of openings. Ceramic grid 115 is placed on top of
gas distribution plate 140.
It is understood that the gas burner of the
embodiment of Fig. 8 will have appropriate brackets to
retain the various components of the burner in place.
Adjustment, control and use of the embodiment shown
in Fig. 8 is similarly to that described previously with
respect to Fig. 2.
The present invention provides a fireplace in which
there is provided a flame to causes the ceramic grid
and/or ceramic logs to glow like embers in a wood fire,
and provide a yellow flame that varies with time e.g. the
yellow flame continuously exhibits rises and falls, and
sideways movement, thereby simulating the fire from a
wood fire.
