U.S. patent application number 11/883883 was filed with the patent office on 2008-07-03 for combustion apparatus.
This patent application is currently assigned to NORITZ CORPORATION. Invention is credited to Takashi Akiyama, Takashi Hasegawa, Itsuo Nagai, Masahiko Shimazu, Takeshi Wakada, Takashi Wakatake, Lin Xie.
Application Number | 20080160467 11/883883 |
Document ID | / |
Family ID | 38308956 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080160467 |
Kind Code |
A1 |
Shimazu; Masahiko ; et
al. |
July 3, 2008 |
Combustion Apparatus
Abstract
A combustion apparatus 1 includes an intermediate member 6
constituted by a premixer 2 and a burner port assembly 3 and an air
passage member 5, the intermediate member 6 being interposed
between two air passage members 5. Fuel gas flows into an opening
row part 10. The opening row part 10 has a number of openings 8
arranged linearly, so that the fuel gas introduced into the row
part 10 is uniformly discharged through each of the openings 8. The
fuel gas discharged through the openings 8 of the row part 10 bumps
into air at mixing spaces 39. Fuel gas discharged through slots is
homogenous and uniform in flow rate. Fuel gas produces a primary
flame in a first combustion part 46 to perform a primary
combustion. Unburned combustible components are discharged outside
through openings of the first combustion part 46 and produce a
secondary flame with air supplied through the distal end portion of
the air passage member 5.
Inventors: |
Shimazu; Masahiko;
(Kobe-shi, JP) ; Akiyama; Takashi; (Kobe-shi,
JP) ; Wakada; Takeshi; (Kobe-shi, JP) ; Xie;
Lin; (Toyonaka-shi, JP) ; Hasegawa; Takashi;
(Hyogo, JP) ; Nagai; Itsuo; (Himeji-shi, JP)
; Wakatake; Takashi; (Akashi-shi, JP) |
Correspondence
Address: |
RADER FISHMAN & GRAUER PLLC
LION BUILDING, 1233 20TH STREET N.W., SUITE 501
WASHINGTON
DC
20036
US
|
Assignee: |
NORITZ CORPORATION
Kobe
JP
|
Family ID: |
38308956 |
Appl. No.: |
11/883883 |
Filed: |
January 30, 2006 |
PCT Filed: |
January 30, 2006 |
PCT NO: |
PCT/JP2006/301494 |
371 Date: |
August 8, 2007 |
Current U.S.
Class: |
431/174 |
Current CPC
Class: |
F23C 2201/20 20130101;
F23D 14/045 20130101; F23D 14/085 20130101; F23C 6/045
20130101 |
Class at
Publication: |
431/174 |
International
Class: |
F23C 5/00 20060101
F23C005/00 |
Claims
1. A combustion apparatus, comprising: at least one premixer
adapted to premix therein fuel gas and air and having an opening
row part with openings arranged in a row; at least one air passage
member of a wall shape having at least one distal air emission
opening at its distal end; and at least one burner port assembly
arranged between two of the air passage members or between the air
passage member and another wall, having a burner port-upstream
passage formed between the opening row part and the burner port
assembly and a first combustion part formed by a space enclosed by
the burner port assembly and the air passage member, so that the
air is supplied to the air passage member, the burner port-upstream
passage, and the premixer, and so that the fuel gas is supplied to
the premixer to be premixed with the air within the premixer, and
whereupon the resulting air-fuel gas mixture is supplied through
the openings of the opening row part into the burner port-upstream
passage to be further mixed with air and to be discharged through
the burner port assembly into the first combustion part in an
oxygen-deficient condition, so as to burn and to further burn upon
air supply through the distal air emission opening of the air
passage member.
2. The combustion apparatus as defined in claim 1, having a mixing
space adjacent to the opening row part within the burner
port-upstream passage, the openings of the opening row part being
open toward the mixing space.
3. The combustion apparatus as defined in claim 1, wherein the
mixing space extends substantially over full width of the opening
row part.
4. The combustion apparatus as defined in claim 1, wherein the air
flows in the burner port-upstream passage in a flowing direction
and the openings of the opening row part are open in a direction
cross to the flowing direction.
5. The combustion apparatus as defined in claim 1, wherein the
burner port assembly comprises a burner port-forming part and two
side walls and has an opening between the two side walls and on the
site opposite to the burner port-forming part, wherein the opening
row part of the premixer is surrounded by the side walls, and
wherein the air is supplied through the opening between the
walls.
6. The combustion apparatus as defined in claim 1, wherein the air
passage member has a combustion part-facing air emission opening
for emitting air therefrom toward the first combustion part.
7. The combustion apparatus as defined in claim 6, wherein the air
passage member has an inclined surface, on which the combustion
part-facing air emission opening is formed.
8. The combustion apparatus as defined in claim 6, wherein the
burner port assembly has a plurality of burner port groups, the
combustion part-facing air emission opening being arranged at a
site corresponding to between the burner port groups of the burner
port assembly.
9. The combustion apparatus as defined in claim 1, wherein the air
passage member has an upstream air emission opening for emitting
air and at upstream of a part of the member defining the first
combustion part, the air emitted through the upstream air emission
opening flowing toward a side of the burner port assembly.
10. The combustion apparatus as defined in claim 1, wherein the
burner port assembly has a central opening and a side opening, so
that the fuel gas is discharged through the side opening slower
than the fuel gas discharged through the central opening, and the
air flows in the vicinity of the side opening of the burner port
assembly.
11. The combustion apparatus as defined in claim 1, wherein the
burner port assembly is constituted by a main body and a
decompression wall disposed at a side of the main body, the main
body and the decompression wall defining therebetween a gap that
has a side opening, and the main body having an opening, through
which a part of the fuel gas flowing in the main body flows into
the gap.
12. The combustion apparatus as defined in claim 1, the openings of
the opening row part each being of a slot-like shape.
13. The combustion apparatus as defined in claim 1, the opening row
part having an inclined surface, on which the openings are
formed.
14. The combustion apparatus as defined in claim 1, the opening row
part having an inner angle at 180 degrees or less.
15. The combustion apparatus as defined in claim 1, the distal end
of the air passage member being of an acute-angled ridge-like
shape.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to combustion apparatuses, and
more particularly to a combustion apparatus recommended to be used
in a water heater or a bath heater.
[0003] 2. Description of the Related Art
[0004] A combustion apparatus is a main component in a water heater
or a bath heater and in widespread use at home as well as at
factories.
[0005] Recently, environmental destruction resulting from acid rain
has become a grave social issue, and thus, there is a pressing need
to reduce a total amount of emission of NOx (nitrogen oxides).
[0006] There is a combustion apparatus employing a combustion
system called the "thick and thin fuel combustion" method adapted
to be used in a small device such as a water heater and to reduce
NOx emissions.
[0007] The "thick and thin fuel combustion" method is designed to
produce a main flame from a lean gas mixture composed of fuel gas
premixed with air of about 1.6 times the amount of the theoretical
amount of air and to arrange around the main flame an auxiliary
flame produced from a rich gas mixture with a small amount of mixed
air and a high gas concentration.
[0008] A combustion apparatus based on the thick and thin
combustion is known for such a configuration as disclosed in the
patent documents 1 and 2, for example.
[0009] A combustion method with a less amount of NOx emissions also
includes a combustion system called the "two-staged combustion"
method.
[0010] The "two-staged combustion" method is adapted to inject a
fuel gas in an oxygen-deficient condition to produce a primary
flame by igniting the gas, so as to produce a secondary flame by
supplying a secondary air to unburned gas.
[0011] The patent document 3 discloses a combustion apparatus
employing the two-staged combustion method.
[0012] Patent Document 1: JP 5-118516A
[0013] Patent Document 2: JP 6-126788A
[0014] Patent Document 3: JP 52-143524A
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0015] A combustion apparatus employing the thick and thin fuel
combustion method generates a less amount of NOx emissions, being
well-reputed in the market, but is disadvantageous in low Turn Down
Ratio (T. D. R). Especially, the combustion apparatus employing the
thick and thin fuel combustion method is disadvantageous in
difficulty to burn in an area having a low heating value.
[0016] Specifically, in the thick and thin fuel combustion method,
a main flame is produced from a lean gas mixture composed of fuel
gas premixed with air of about 1.6 times the amount of the
theoretical amount of air, as described above. The gas mixture has
a low burning rate because of its leanness.
[0017] The combustion apparatus employing the thick and thin fuel
combustion method is provided with a fan for facilitating
generation of a lean gas mixture, but the fan would become
deteriorated due to years of use thereof, resulting in gradually
reducing its blowing volume. Clog of a filter of the fan might
reduce its air blowing volume. Such a reduced air blowing volume
caused by aging is liable to reduce an amount of air in the gas
mixture producing a main flame, rendering the amount of mixed air
approaching the theoretical amount of air. As a result, a
combustion speed of the main flame is liable to become more rapid
due to aging. Therefore, the proximal end of flame is liable to
gradually approach burner ports due to aging. Thus, combustion in
an area having a low heating value would render the proximal end of
flame approaching to burner ports, resulting in damaging the burner
ports. Consequently, a combustion apparatus employing the thick and
thin fuel combustion method is forced to restrict combustion in an
area having a low heating value on an anticipated aging.
[0018] In addition, the thick and thin fuel combustion method
causes such a complaint as a narrow range of usable gas.
Specifically, fuel gas supplied by a gas maker may be constituted
by a single component, but in many cases, by a plurality of
components. That causes different combustion speed depending on
makers of fuel gas even if their amounts of heat generation
(amounts of heat per unit volume) are the same among them.
[0019] Since the thick and thin fuel combustion method produces a
main flame in an air excess condition, fuel gas having a slow
combustion speed might cause blow off, resulting in an unstable
combustion.
[0020] In contrast, the two-staged combustion method can have a
higher Turn Down Ratio than the thick and thin fuel combustion
method. Further, a wide variety of fuel gas is available. However,
the two-staged combustion method burns fuel gas in an
oxygen-deficient condition, resulting in an unstable combustion.
Provably for this reason, we found none of practical devices such
as water heaters that are offered commercially and employ the
two-staged combustion method.
[0021] In order to put to practical use as a combustion apparatus,
it is necessary to produce such flame as to uniformly spread over a
certain area. This can be achieved by producing a primary flame and
a secondary flame in a balanced manner and uniformly throughout the
entire area of a combustion site.
[0022] However, it is difficult to produce the primary and the
secondary flames in a balanced manner and to uniformly distribute
the flames throughout the entire area of the combustion site. For
example, the primary flame might be partly extinguished, resulting
in an excessive secondary flame at downstream thereof, or all fuel
might burn out at a site to produce the primary air, resulting in
extinguishment of the secondary flame at downstream thereof.
Therefore, we found no combustion apparatus employing the
two-staged combustion method, among devices such as water heaters
having put to practical use.
[0023] An object of the present invention made in view of the
problems and drawbacks in the art described above is therefore to
improve a combustion apparatus performing two-staged combustion and
to develop such a combustion apparatus as producing a primary flame
and a secondary flame in a balanced manner and spreading the flames
uniformly throughout the entire area of a combustion site.
Means to Solve the Problem
[0024] In order to solve the problems and drawbacks described
above, an aspect of the present invention provided herein is a
combustion apparatus, including at least one premixer adapted to
premix therein fuel gas and air and having an opening row part with
openings arranged in a row, at least one air passage member of a
wall shape having at least one distal air emission opening at its
distal end, and at least one burner port assembly arranged between
two of the air passage members or between the air passage member
and another wall, having a burner port-upstream passage formed
between the opening row part and the burner port assembly and a
first combustion part formed by a space enclosed by the burner port
assembly and the air passage member, so that the air is supplied to
the air passage member, the burner port-upstream passage, and the
premixer, and so that the fuel gas is supplied to the premixer to
be premixed with the air within the premixer, and whereupon the
resulting air-fuel gas mixture is supplied through the openings of
the opening row part into the burner port-upstream passage to be
further mixed with air and to be discharged through the burner port
assembly into the first combustion part in an oxygen-deficient
condition, so as to burn and to further burn upon air supply
through the distal air emission opening of the air passage
member.
[0025] The present aspect has the premixer, in which fuel gas and
air are premixed. The premixer has the opening row part with the
openings arranged in a row, through which the fuel gas is
distributed to the burner port-upstream passage. The fuel gas is
mixed with air also in the burner port-upstream passage. Therefore,
according to the configuration of the present aspect, the resulting
air-fuel gas mixture flowing in the burner port-upstream passage is
well mixed and homogenous. Consequently, the homogenized fuel gas
is discharged through all areas of walls of the burner port
assembly. That produces a primary flame and a secondary flame in a
balanced manner and spreads the flames uniformly throughout the
entire area of a combustion site.
[0026] It is preferable to have a certain space adjacent to the
opening row part and within the burner port-upstream passage. This
space becomes a mixing space in which fuel gas and air are mixed.
The openings of the opening row part are preferably open toward the
mixing space.
[0027] Further, it is preferable that the mixing space extends
substantially over full width of the opening row part.
[0028] The mixing space extending in this way promotes
homogenization of pressure.
[0029] It is preferable that the openings of the opening row part
are open in a direction cross to a flowing direction of the air
flowing in the burner port-upstream passage.
[0030] Fuel gas is discharged in a direction cross to the air flow
direction through the openings of the opening row part, having
frequent bumping into the air. That promotes mixture of the fuel
gas and the air.
[0031] A variety of configurations can be considered as the burner
port assembly. An employed configuration, for example, may be such
that the burner port assembly includes a burner port-forming part
and two side walls and has an opening between the two side walls
and on the site opposite to the burner port-forming part, wherein
the opening row part of the premixer is surrounded by the side
walls, and wherein the air is supplied through the opening between
the walls.
[0032] Further, it is recommended to have such a configuration that
the air passage member has a combustion part-facing air emission
opening for emitting air therefrom toward the first combustion
part. At this time, it is preferable that the burner port assembly
has a plurality of burner port groups, the combustion part-facing
air emission opening being arranged at a site corresponding to
between the burner port groups of the burner port assembly.
[0033] The first combustion part is a site where the primary flame
is produced, whereas the secondary flame is produced outside of the
first combustion part by air supplied through the distal air
emission opening. The combustion part-facing air emission opening
is arranged so as to discharge air from the side toward between the
burner port groups of the burner port assembly, so that the air is
blown from surroundings of the burner port groups, thereby ensuring
stabilizing the primary flame. Further, the air is supplied from
under the primary flame, so as to produce the secondary flame at an
early stage and perform a complete combustion of fuel gas adjacent
to the primary flame. That allows compact combustion space, thereby
shortening the total length of the primary and the secondary
flames. The proximal end of the secondary flame is also
stabilized.
[0034] It is recommended that the air passage member has an
inclined surface, on which the combustion part-facing air emission
opening is formed.
[0035] According to this arrangement, air is jetted in an oblique
direction, without obstructing the flow of a main part of the
primary flame or the flow of fuel gas.
[0036] Further, according to this arrangement, the air is
introduced along the flow of the main part of the primary flame or
the flow of fuel gas, without accumulating in the vicinity of the
wall of the air passage member.
[0037] Specifically, fuel gas flows substantially parallel to the
wall within the first combustion part. Thus, in the case of
introducing air in a direction perpendicular to the first
combustion part from the air passage member, the air bumps into the
primary flame or the fuel gas, resulting in possible accumulation.
If air accumulates in the vicinity of the wall of the air passage
member, the accumulated air may cause combustion of surrounding
unburned gas and produce flame in the vicinity of the wall of the
air passage member. The wall may be excessively heated and
glow.
[0038] In response, the air jetted in an oblique direction is
introduced along the flow of the primary flame or the flow of fuel
gas, so as to produce the secondary flame at a site distant from
the air passage member. That avoids glowing of the wall of the air
passage member.
[0039] Further, it is also recommended that the air passage member
has an upstream air emission opening for emitting air and at
upstream of a part of the member defining the first combustion
part, the air emitted through the upstream air emission opening
flowing toward a side of the burner port assembly.
[0040] According to the above-mentioned arrangement, air discharged
through the upstream air emission opening flows toward the side of
the burner port assembly, so that oxygen is supplied to the side of
the burner port assembly. That produces stable flame at the side of
the burner port assembly, holding the proximal end of the primary
flame. As a consequence, the primary flame is stabilized.
[0041] Still further, it is also recommended that the burner port
assembly has a central opening and a side opening, so that the fuel
gas is discharged through the side opening slower than the fuel gas
discharged through the central opening, and the air flows in the
vicinity of the side opening of the burner port assembly.
[0042] This arrangement makes a clear distinction between the
burner port for producing a main part of the primary flame and the
burner port for producing an auxiliary flame.
[0043] Specifically, according to the above-mentioned arrangement,
the flow rate of fuel gas discharged through the side opening is
slower than that of fuel gas discharged through the central
opening, and whereby flame produced at the side opening is hardly
blown off. Further, air is supplied to the vicinity of the side
opening, so that fuel gas discharged through the side opening
performs a relatively stable combustion and holds the proximal end
of the primary flame. As a consequence, the primary flame is
stabilized.
[0044] The side opening may be constituted in such a manner that
the burner port assembly is constituted by a main body and a
decompression wall disposed at a side of the main body, the main
body and the decompression wall defining therebetween a gap that
has a side opening, and the main body having an opening, through
which a part of the fuel gas flowing in the main body flows into
the gap.
[0045] According to the above-mentioned arrangement, fuel gas is
introduced through the opening formed on the main body into the gap
formed between the side wall and the decompression wall, but an
amount of the fuel gas (more properly, the fuel gas premixed with
air) is restricted by the opening, so that the flow rate of the
fuel gas discharged through the side opening becomes slower than
that of fuel gas discharged through other sites.
[0046] The openings of the opening row part each may be of a
slot-like shape.
[0047] Further, the opening row part may have an inclined surface,
on which the openings are formed. At this time, the opening row
part has preferably an inner angle at 180 degrees or less.
[0048] Fuel gas is discharged in an oblique direction by forming
the openings on the inclined surface. That allows the fuel gas more
frequent contact with air flow, promoting mixture of fuel gas and
air.
[0049] Further it is recommended that the distal end of the air
passage member is of an acute-angled ridge-like shape.
[0050] The air emission opening is formed on the distal end of the
air passage member, so as to supply secondary air. According to the
above-mentioned arrangement, the distal end of the air passage
member is of an acute-angled ridge-like shape, thereby ensuring
less air flowing around within the member. That stabilizes a
discharging direction of air.
ADVANTAGEOUS EFFECT OF THE INVENTION
[0051] The combustion apparatus of the present invention produces
the primary and the secondary flames in a balanced manner and
uniformly distributed throughout the entire area of the combustion
site, being practical.
[0052] Further, the combustion apparatus of the present invention
achieves a less amount of NOx emissions and a higher Turn Down
Ratio. Still further, the combustion apparatus of the present
invention is widely adapted to fuel gas having any combustion
speed, so as to be used for all types of gas.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a sectional perspective view conceptually
illustrating a configuration of a combustion apparatus of the
present invention;
[0054] FIG. 2 is a perspective view of a combustion apparatus in a
practical embodiment of the present invention;
[0055] FIG. 3 is a plan view of the combustion apparatus in FIG. 2
accommodated in a casing;
[0056] FIG. 4 is a sectional view taken along the lines A-A of FIG.
3;
[0057] FIG. 5 is a sectional view of the combustion apparatus in
FIG. 2;
[0058] FIG. 6 is a perspective view showing an internal structure
of the combustion apparatus broken in a stepwise fashion;
[0059] FIG. 7 is an exploded perspective view of the combustion
apparatus in FIG. 2;
[0060] FIG. 8 is an exploded sectional view of the combustion
apparatus in FIG. 2;
[0061] FIG. 9 is a perspective view of a premixer of the combustion
apparatus in FIG. 2;
[0062] FIG. 10 is a sectional view taken along the lines A-A of
FIG. 9;
[0063] FIG. 11 is a sectional view taken along the lines B-B of
FIG. 9;
[0064] FIG. 12 is a perspective view of an air passage member of
the combustion apparatus in FIG. 2;
[0065] FIG. 13 is an enlarged view of a concaved part of the air
passage member in FIG. 12;
[0066] FIG. 14 is a perspective view of a burner port assembly of
the combustion apparatus in FIG. 2;
[0067] FIG. 15 is an enlarged front view of a trough for engagement
of the burner port assembly in FIG. 14;
[0068] FIG. 16 is a side view showing the burner port assembly
joined to the premixer;
[0069] FIG. 17 is an enlarged view showing the vicinity of the
proximal end of the burner port assembly in FIG. 16;
[0070] FIG. 18 is an illustration diagram showing a positional
relationship between openings of the premixer and ribs of the air
passage member;
[0071] FIG. 19 is an illustration diagram showing a positional
relationship between openings of a premixer and ribs of an air
passage member of another embodiment;
[0072] FIG. 20 is an illustration diagram showing air flow within
the air passage member of the present embodiment;
[0073] FIG. 21 is an illustration diagram showing air flow within
the air passage member of another embodiment;
[0074] FIG. 22 is an exploded perspective view of a combustion
apparatus of another embodiment;
[0075] FIG. 23 is an exploded perspective view of a combustion
apparatus of still another embodiment; and
[0076] FIG. 24 is a partly enlarged plan view showing a positional
relationship between burner port groups of the burner port assembly
and combustion part-facing air emission openings of the air passage
member.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0077] Now, an embodiment of the present invention will be
described below in detail, making reference to the accompanying
drawings. First, an outline configuration and basic functions of
the present invention will be described, referring to a schematic
view of FIG. 1. An embodiment in FIG. 1 conceptually illustrates
the present invention.
[0078] In the following descriptions, the vertical positional
relationship is based on a combustion apparatus 1 positioned
upright and producing flame at an upper part thereof. Terms
"upstream" and "downstream" are based on an air or fuel gas flow. A
"width direction" denotes a lateral direction (a direction of an
arrow "W" in the figure) with a part having the maximal area of the
combustion apparatus facing the front.
[0079] The combustion apparatus 1 of the present embodiment is used
by accommodating more than one apparatus in a casing or alone. The
combustion apparatus 1 includes a premixer 2, a burner port
assembly 3, and two air passage members 5. In the combustion
apparatus 1, the premixer 2 and the burner port assembly 3 are
engaged with each other to constitute an intermediate member 6,
which is interposed between the two air passage members 5. However,
in the actual use, a plurality of the air passage members 5 and a
plurality of the intermediate members 6 are alternately arranged to
form a planar shape in an order such as the air passage member 5,
the intermediate member 6, the air passage member 5, the
intermediate member 6, the air passage member 5, and so on.
[0080] The premixer 2, a component of the combustion apparatus 1,
serves to premix fuel gas and air therewithin. The premixer 2
includes a mixing part 7 having a curved passage and an opening row
part 10 having openings 8 arranged in a row. The opening row part
10 has a cavity of a substantially square shape in a cross section
extending lengthwise and linearly.
[0081] The air passage member 5 generally has a thin wall shape.
The air passage member 5 is constituted by a first face 11 and a
second face 12, each made of a thin plate, in such a manner that
the first and the second faces 11 and 12 are connected with forming
a narrow gap therebetween, the three sides except the bottom being
joined, thereby defining a cavity to be an air passage 13
inside.
[0082] Specifically, the first and the second faces 11 and 12 are
made by folding a unitary plate. Its distal end has an acute-angled
bent portion 14, the bent portion 14 making up a top portion 9,
which extends in ridge-like lines.
[0083] The proximal end of the air passage member 5 is open between
plates of the first and the second faces 11 and 12, forming an air
inlet 15.
[0084] In the air passage member 5, openings for emitting air are
formed at three areas. Since the air passage members 5 and the
intermediate members 6 are alternately arranged to form a planar
shape, as described above, the same numbers of openings are formed
at the same portions of the first and the second faces 11 and 12 of
the air passage members 5.
[0085] The openings for emitting air are formed at the distal end,
a position facing to a first combustion part 46, and a position
facing to the intermediate member 6, roughly describing.
[0086] Specifically, the plates of the first and the second faces
11 and 12 of the air passage member 5 are arranged in parallel in
their most parts, but are angularly folded only at their distal
ends, forming inclined surfaces 16 and 17 at the first and the
second faces, respectively. The inclined surfaces 16 and 17 each
have distal openings 20. Further, distal openings 21 are formed at
a tip (ridge line). The distal openings 20 and 21 are formed for
supplying a secondary air to a secondary flame.
[0087] The first and the second surfaces 11 and 12 of the air
passage member 5, as shown in FIG. 1, has the air passage 13 formed
in such a manner as being narrower at its distal end than at its
proximal end and having steps at positions corresponding to the
proximal end of the first combustion part 46, which steps also
constitute inclined surfaces 22. Combustion part-facing air
emission openings 23 are formed at each of the steps. The air
emission openings 23 are designed to supply the secondary air
therethrough to the primary flame in the first combustion part 46,
so as to bum part of the primary flame to produce the secondary
flame within a part of the first combustion part 46.
[0088] Further, air emission openings (upstream air emission
openings) 48 are formed at a position facing to the intermediate
member 6. The air emission openings (upstream air emission
openings) 48 serve to stabilize an auxiliary flame by supplying air
therethrough to each side of the burner port assembly 3.
[0089] The burner port assembly 3 is mainly constituted by a main
body 25 and decompression walls 26. The main body 25 of the burner
port assembly 3 is made by bending a piece of metal plate, having a
top face 30 functioning as burner ports and two side walls 31 and
32 bent at a substantially 90 degree angle at the both edges of the
top face 30. Right and left sides of the burner port assembly 3 are
closed with only its bottom in the figure opened. The top face 30
of the burner port assembly 3 has an elongated shape with an A-line
shape cross section. The top face 30 has slots regularly arranged,
which constitute burner ports 33. The burner ports 33 formed at the
main body 25 function as "central openings."
[0090] The side walls 31 and 32 each have a protruding part 34
protruding outwards (in a thickness direction) at its intermediate
portion. The protruding part 34 is formed across the full width of
the burner port assembly 3.
[0091] Open ends of the side walls 31 and 32 are bent at a
substantially 90 degree angle twice as shown in the figure, each
forming outside a trough (or a gutter) 38 for engagement. The
troughs 38 have bottom walls 36 vertical to and outer walls 37
parallel to the respective side walls 31 and 32.
[0092] The decompression walls 26 are attached to the main body 25,
as described above. The decompression walls 26 are fixed to the
respective side walls 31 and 32 of the main body 25, forming gaps
29 between the respective side walls 31 and 32 of the main body 25.
The gaps 29 each have an opening at a top of the figure. The
opening functions as a side opening 27.
[0093] Openings 35 are formed at the side walls 31 and 32 and at
positions facing to the decompression walls 26. The gaps 29 are
communicated with an inner space of the main body 25 via the
openings 35.
[0094] Next, a relationship between components will be described
below.
[0095] In the present embodiment, as described above, the premixer
2 and the burner port assembly 3 are engaged, thereby constituting
the intermediate member 6. More specifically, the opening row part
10 of the premixer 2 is placed between the side walls 31 and 32 of
the burner port assembly 3. In the actual producing process, the
premixer 2 is inserted from the opening (bottom in the figure)
between the side walls 31 and 32 of the burner port assembly 3 to
join the both members.
[0096] The side walls 31 and 32 and the opening row part 10 have
partly contact with each other by their concave and convex shapes
not shown, thus being unified. As described above, the side walls
31 and 32 and the opening row part 10 have partly contact with each
other by their concave and convex shapes, and in other words, they
partly keep away from each other. The cross section in FIG. 1 shows
a cross section at a site where the side walls 31 and 32 and the
opening row part 10 keep away from each other.
[0097] Sites corresponding to the protruding parts 34 of the side
walls 31 and 32 are away from the accommodated opening row part 10.
The protruding parts 34 each correspond to a row of openings 8 of
the opening row part 10. Thus, outsides of the openings 8 of the
opening row part 10 keep away from the side walls 31 and 32, so as
to form spaces (mixing spaces) 39 wider than the other portions.
The spaces 39 extend over full width corresponding to all the
openings 8.
[0098] A relatively large space 47 is formed between the side walls
31 and 32 and between the top of the opening row part 10 and the
top face 30 of the burner port assembly 3. In the present
embodiment, the mixing spaces 39 and the space 47 downstream of the
opening row part 10 form a burner port-upstream passage 49.
[0099] The air passage members 5 are attached to the both sides of
the intermediate member 6. Each of the air passage members 5 is
joined with the intermediate member 6 by engaging the air inlet 15
of the proximal end of the member 5 with the trough 38 of the
burner port assembly 3. Specifically, the outer wall 37 of the
trough 38 is inserted into the air inlet 15 and the tip of the air
passage member 5 is inserted into the trough 38, and whereby the
air passage member 5 is brought into contact with the bottom wall
36 of the trough 38.
[0100] The air passage member 5 and the intermediate member 6 (the
burner port assembly 3) have partly contact with each other by the
concave and convex shape, and thus the both members are unified.
The both members have partly contact with each other as just
described, and in other words, keep partly away from each other.
The cross section of FIG. 1 shows a site where the air passage
member 5 and the intermediate member 6 (burner port member 3) keep
away from each other so as to facilitate understanding their
functions. However, at an end (the bottom edge in the figure)
upstream of the combustion apparatus 1, a space 40 between the air
passage member 5 and the intermediate member 6 are closed by the
bottom wall 36 of the trough 38. Thus, the space 40 between the air
passage member 5 and the intermediate member 6 is not directly
communicated with outside at the proximal end.
[0101] The burner port assembly 3 is interposed between the two air
passage members 5 as described above, the top face 30 of the
assembly 3 lying below (in the figure) the top level of the air
passage members 5 and, so to say, buried between the air passage
members 5. Therefore, a space ahead of the top face 30 of the
assembly 3 is partitioned by walls of the two air passage members
5. In the present embodiment, a space enclosed by the top face 30
of the assembly 3 and the two air passage member 5 functions as the
first combustion part 46.
[0102] Next, a function of the combustion apparatus 1 will be
described in detail below.
[0103] A number of the combustion apparatus 1 are opposed within a
casing not shown, with air being sent by means of a fan 41 from the
bottom in the figure. Fuel gas is introduced into the apparatus 1
through a gas inlet 43 of the premixer 2 by means of a nozzle
42.
[0104] First, air flow will be described. The air flow is shown by
thin lines in FIG. 1.
[0105] Air blow generated by the fan 41 is straightened through
openings 45 of a straightening vane 44 so as to be introduced into
the combustion apparatus 1 through the proximal end (bottom in the
figure) of the apparatus 1.
[0106] There are three routes for air introduced into the apparatus
1. The first route passes through inside the air passage member 5,
the air flowing through the air inlet 15 formed at the proximal end
of the air passage member 5 into the air passage member 5 and going
up to the distal end through the air passage 13 within the air
passage member 5. Most of the air is discharged outside through the
distal openings 20 and 21.
[0107] Part of the air flowing in the air passage member 5 is
discharged also through the combustion part-facing air emission
openings 23 and the air emission openings (upstream air emission
openings) 48.
[0108] The air having been discharged through the air emission
openings 23 is discharged in a direction diagonally to the front of
an axis line of the apparatus 1 from the inclined surfaces 22 of
the steps.
[0109] Further, the air having been discharged through the air
emission openings 48 flows in the space 40 between the air passage
member 5 and the intermediate member 6 to the side of the burner
port assembly 3.
[0110] The second route passes through inside the intermediate
member 6. The intermediate member 6 is constituted by the opening
row part 10 of the premixer 2 interposed between the side walls 31
and 32 of the burner port assembly 3. Gaps (openings) exist between
the opening row part 10 and the burner port assembly 3 and a part
of the gaps (openings) is open at the bottom of the intermediate
member 6.
[0111] Therefore, the air is introduced through the openings 28
into between the premixer 2 and the side walls 31 and 32 of the
burner port assembly 3.
[0112] This air flows through the gaps between the side walls 31
and 32 and the opening row part 10, entering the mixing spaces 39,
and then flowing into the space 47 between the opening row part 10
and the top face 30 of the burner port assembly 3. That is, the air
described above flows in the burner port-upstream passage 49.
Finally, the air is discharged through the slots, i.e., the burner
ports 33, into the first combustion part 46. Part of the air having
entered the space 47 enters the gaps 29 between the main body 25
and the side walls 31 and 32 through the openings 35 formed on the
side walls 31 and 32 of the main body 25 and is discharged into the
first combustion part 46 through the side openings 27.
[0113] Next, the third route for air will be described in detail
below. The third route is a route for the primary air, which is
introduced with fuel gas through the gas inlet 43 of the premixer
2. The third route is the same route as that of fuel gas flow,
being illustrated in the following description as that of the fuel
gas flow. The fuel gas flow is indicated by arrows in solid line in
FIG. 1.
[0114] Fuel gas is introduced into the third route with the primary
air through the gas inlet 43 of the premixer 2 to be mixed with air
in a part such as the mixing part 7, the resulting mixture flowing
into the opening row part 10. The opening row part 10 has a number
of openings 8 arranged linearly, so that the fuel gas having been
introduced thereinto is evenly discharged through each of the
openings 8. The fuel gas having been discharged through the
openings 8 of the row part 10 enters the mixing spaces 39 formed
between the side walls 31 and 32 of the burner port assembly 3 and
the openings 8 of the row part 10 to be mixed with air flowing in
the burner port-upstream passage 49 (including the mixing spaces
39).
[0115] The air flowing in the burner port-upstream passage 49
(including the mixing spaces 39) flows vertically (from bottom to
top), whereas the fuel gas having been discharged through the
openings 8 of the row part 10 flows in a direction perpendicular to
the air flow. Thus, the fuel gas hits hard the air also at the
mixing spaces 39, and whereby mixing of the fuel gas with the air 5
is facilitated. Further, the mixing spaces 39 each extend
throughout in a longitudinal direction of the opening row part 10,
thereby smoothing pressure.
[0116] After having passed through the mixing spaces 39, the fuel
gas flows into the space 47, during which the mixing of the fuel
gas with the air is enhanced. After that, the fuel gas flows in the
same way as the flow in the burner port-upstream passage 49,
entering the space 47 between the opening row part 10 and the top
face 30 of the burner port assembly 3, and being mostly discharged
through the slots (the burner ports) 33 into the first combustion
part 46. Part of the air having entered the space 47 enters the
gaps 29 between the decompression walls 26 and the sidewalls 31 and
32 of the main body 25 through the openings 35 formed on the side
walls 31 and 32, being discharged through the side openings 27 into
the first combustion part 46.
[0117] The fuel gas having been discharged through the burner ports
33 is mixed with air within the premixer 2 and further mixed with
air within the mixing spaces 39, and thus, being uniformed and
being discharged through the burner ports 33 at a uniform rate.
[0118] However, though the fuel gas discharged through the burner
ports 33 is mixed with air, an amount of the air is below a
theoretical amount of air. That is why the fuel gas discharged
through the burner ports 33 is in an oxygen-deficient condition,
failing in achieving a complete combustion only with this fuel
gas.
[0119] Ignited, the fuel gas produces the primary flame in the
first combustion part 46, so as to perform a primary combustion.
However, the fuel gas is not completely burned because of
insufficient oxygen as described above, resulting in generating a
great deal of unburned combustible component.
[0120] The unburned combustible component is discharged outside
through opening of the first combustion part 46. Herein, air is
supplied to outside of the first combustion part 46 through the
distal end of the air passage member 5. Therefore, the unburned
combustible component performs a secondary combustion upon oxygen
supply. In other words, an area outside of the first combustion
part 46 functions as a secondary combustion part and produces the
secondary flame.
[0121] Further, in the present embodiment, air is supplied to the
proximal end of the primary flame, so as to produce an auxiliary
flame in the proximal end of the primary flame.
[0122] In the present embodiment, fuel gas is discharged not only
through the burner ports 33, i.e., the "central openings," but also
through the side openings 27. However, the flow rate of fuel gas
discharged through the side openings 27 is slower than that of fuel
gas discharged through the burner ports 33. Specifically, the fuel
gas enters the gaps 29 between the decompression walls 26 and the
side walls 31 and 32 of the main body through the openings 35
formed on the side walls 31 and 32, being discharged through the
side openings 27 into the first combustion part 46. That restricts
an amount of fuel gas entering the gaps 29, resulting in a small
amount of fuel gas discharged through the side openings 27.
Conversely, the side openings 27 each have a large opening space.
Thus, the fuel gas discharged through the side openings 27 has a
low flow rate.
[0123] Further, as described above, part of air passing though the
air passage member 5 is discharged through the air emission
openings (upstream air emission openings) 48 into the space 40
between the air passage member 5 and the intermediate member 6,
reaching the side faces of the burner port assembly 3 through the
space 40. Therefore, the side faces of the assembly 5 3 is richer
in oxygen than other parts, ensuring that the fuel gas discharged
through the side openings 27 performs a relatively stable
combustion with reception of air supply.
[0124] Coupled with a low flow rate of the fuel gas as described
above, a stable auxiliary flame is produced in the vicinity of the
side openings 27. The proximal end of the primary flame is held by
small flames produced in the vicinity of the side openings 27.
[0125] Still further, in the present embodiment, the air having
been discharged through the combustion part-facing air emission
openings 23 stabilizes the secondary flame. Specifically, in the
present embodiment, the inclined surfaces 22 are located at the
first and the second faces 11 and 12 of the air passage member 5
and at sites corresponding to the proximal ends of the first
combustion part 46. The air emission openings 23 are formed on the
inclined surfaces 22, thereby supplying air diagonally to an air
flow direction from the proximal end of the first combustion part
46. Thus, the supplied air is supplied into the first combustion
part 46 without obstructing the primary flame or the flow of
unburned gas. As a consequence, part of unburned gas within the
first combustion part 46 starts combustion and partly produces a
secondary flame, which merges with the external secondary flame,
thereby stabilizing the secondary flame produced outside.
[0126] Yet further, in the present embodiment, the combustion
part-facing air emission openings 23 are diagonally open, without
obstructing the primary flame or the flow of unburned gas, as
described above. Consequently, the secondary flame is produced at a
distance from the air passage member 5 and does not excessively
heat the air passage member 5.
[0127] The combustion apparatus of the present embodiment therefore
stabilizes both the primary and the secondary flames, thus being
practical.
[0128] Now, a more practical configuration example of the present
invention will be described in referring to the following figures
after FIG. 2. The embodiment described below is practically
designed for embodying the present invention and has the most
recommended configuration.
[0129] A combustion apparatus shown in the figures following after
FIG. 2 has the same basic configuration and basic function as those
in the above-mentioned embodiment, but is practically designed to
detail. The same numerals are assigned to components that carry out
the same functions as those in the foregoing embodiment, and
descriptions of the duplicated functions are simplified.
[0130] A plurality of combustion apparatuses 1 shown in FIG. 2 are
accommodated in parallel in a casing 54 as shown in FIGS. 3 and 4.
The combustion apparatus 1 of the present embodiment also includes
a premixer 2, a burner port assembly 3, and air passage members 5.
The premixer 2 and the burner port assembly 3 are engaged to
constitute an intermediate member 6, which is interposed between
the two air passage members 5.
[0131] A shape of the premixer 2 is shown in FIGS. 9, 10, and 11.
The premixer 2 is formed by a unitary sheet steel pressed and
molded into an unfolded form having a concave and convex shape on
its surface, which is bent and connected at its periphery by means
of a spot welding. The spot welding is done at flanges 51 of the
periphery.
[0132] The premixer 2 after assembly has such a shape that a front
plate 52 as shown in FIGS. 8 and 9 is coupled with a rear plate 53
symmetric to the front plate 52. The premixer 2 has a rounded shape
with a flat top part 50 and is sealed at its periphery so as to
prevent gas from being leaked.
[0133] The premixer 2 forms therein a unitary gas passage between
the front and the rear plates 52 and 53. Specifically, the sheet
steel forms a space at a portion where the concave and convex
shapes of the front and the rear plates 52 and 53 correspond to
each other, thereby forming the gas passage by the space.
[0134] In the premixer 2 employed in the present embodiment, as
shown in FIG. 9, the gas passage is roughly divided into upper and
lower parts. More specifically, the gas passage mainly consists of
a mixing passage 19 and an opening row part 10.
[0135] Referring to FIG. 9, the mixing passage 19 is formed at the
lower part of the premixer 2, from an entrance of the gas passage
to the opening row part 10. Starting with the entrance of the
passage, a gas inlet 43 is open at the corner of the lower part of
the combustion apparatus 1. The gas inlet 43 has therein a squeezed
portion 55 where its cross-sectional area is locally squeezed and
at downstream thereof a diameter expansion portion 56 where the
cross-sectional area is gradually expanded. A uniform cross-section
portion 57 having a uniform cross-sectional area continues at
further downstream. The passage from the gas inlet 43 through the
squeezed portion 55 and the diameter expansion portion 56 to the
uniform cross-section portion 57 is straight.
[0136] The end of the uniform cross-section portion 57 is connected
to the opening row part 10 with the passage bent at a right
angle.
[0137] Herein, in the present embodiment, a portion just before the
opening row part 10 is not squeezed.
[0138] Referring to FIG. 9, the opening row part 10 is located at
the upper part of the premixer 2 and extends throughout in a
longitudinal direction. A cross-sectional area of the row part 10,
in other words, the space between the front and the rear plates 52
and 53 at the row part 10 is wide, as shown in FIGS. 10 and 11.
[0139] Referring to FIGS. 10 and 11, the row part 10 has a cross
section of two-tiered configuration with a small area portion 58
having a slightly small cross-sectional area near the top part
50.
[0140] Specifically, the row part 10 has such a cross section that
the top part 50 is flat with upper part vertical walls 81
vertically extending from its both sides. Bottom edges of the upper
part vertical walls 81 each are connected to inclined walls,
extending slightly outward. Further, bottom edges of the inclined
walls are contiguous to lower part vertical walls 82.
[0141] The small area portion 58, which is an outer surface of the
row part 10, has a number of openings 8 at both of the front and
the rear plates 52 and 53. The openings 8 are formed linearly in a
row at predetermined intervals.
[0142] In the present embodiment, the openings 8 are formed only at
the front and the rear sides of the row part 10, and not at the top
part 50.
[0143] Next, the air passage member 5 will be described in detail
below, in referring to FIGS. 8, 12, and 20. The air passage member
5 is also formed by a unitary sheet steel pressed and molded into
an unfolded form having a concave and convex shape on its surface,
which is bent and connected at its periphery by means of a spot
welding. The air passage member 5, as shown in FIG. 8, is
constituted by a first face plate 11 and a second face plate 12
joined at their periphery with a small gap, which forms a cavity to
be an air passage 13.
[0144] The distal end of the air passage member 5 has an
acute-angled bent portion, which constitutes a top portion 9
extending in ridge-like lines.
[0145] The air passage member 5, as shown in FIG. 12, has flanges
83 at both sides adjoining the bent portion, the flanges 83 being
secured each other at the both sides by means of a spot
welding.
[0146] The proximal end of the air passage member 5 is open between
the first and the second face plates 11 and 12, which form an air
inlet 15.
[0147] Referring to FIG. 12, the air passage member 5 is of a thin
wall shape and roughly divided into three areas in a height
direction in its upright position.
[0148] Specifically, the areas consists of an introduction portion
60 from the proximal end to about one third of the total height, an
intermediate portion 61 from the introduction portion 60 to about
two thirds thereof, and a first combustion part-forming portion 62
of another one third near the distal end.
[0149] The air passage member 5 constitutes a passage headed toward
the distal end from the air inlet 15, a cross-sectional area of the
passage becoming narrower toward the distal end.
[0150] Specifically, the portion from the air inlet 15 to about one
third of the total height (the introduction portion 60), as shown
in FIG. 8, has a substantially uniform cross-sectional area. In
other words, in the introduction portion 60, the first and the
second face plates 11 and 12 are parallel without changing
intervals therebetween as shown in the cross section in FIG. 8.
[0151] The intermediate portion 61 has a roughly tapered shape.
[0152] Specifically, as shown in the figures, the intermediate
portion 61 is extended in a tapered shape with its lower part being
wider and narrowing as going upward. However, a protruding portion
84 is formed between the distal end of the tapered portion and the
first combustion part-forming portion 62. Both sides of outer walls
defining the protruding portion 84 are parallel.
[0153] The first combustion part-forming portion 62 has a
substantially uniform cross-sectional area (except the top portion
9), but its cross-sectional area per unit length is about one third
compared with that of the introduction portion 60. Steps composed
of inclined surfaces 22 are formed between the portion 62 and the
portion 61.
[0154] The air passage member 5 has openings for emitting air at
three areas. The areas consist of the distal end portion, a
position facing to a first combustion part 46, and a position
facing to the intermediate member 6, roughly describing.
[0155] Specifically, the first and the second face plates 11 and 12
of the air passage member 5 are angularly folded at their distal
ends, forming inclined surfaces 16 and 17 at the first and the
second face plates, respectively. The inclined surfaces 16 and 17
each, as shown in FIG. 12, have circular distal openings 20.
Circular distal openings 21 are also formed at the tip portion
(ridge line portion).
[0156] Further, in the present embodiment, the top portion 9 and
the inclined surfaces 16 and 17 have distal openings 63 and 64 of
short and long slot-like shapes. The shorter distal openings 63
each extend over entire heights of the inclined surfaces 16 and 17
and the top portion 9. The longer distal openings 64 each extend
from portions where the first and the second face plates 11 and 12
are in parallel to the top portion 9.
[0157] The longer slots (distal openings) 64 are larger in number
than the shorter slots (distal openings) 63; two or three of the
longer slots 64 being arranged in a row, thereafter the shorter
slot 63 being arranged, then two or three of the longer slots 64
being arranged in a row, and so on. Such a sequence of arrangement
is made over all area in a longitudinal direction of the air
passage member 5.
[0158] The above-mentioned circular distal openings 20 and 21 are
formed between two of the slots (distal openings) 63 or 64.
[0159] The distal openings 20 and 21 are, as well as in the
foregoing embodiment, formed for supplying a secondary air to a
secondary flame.
[0160] Further, combustion-part-facing air emission openings 23 are
formed on the inclined surface 22 between the first combustion-part
forming portion 62 and the intermediate portion 61. The air
emission openings 23 are to supply a secondary air to a primary
flame taking place in the first combustion part 46, so as to burn a
part of the primary flame and produce a secondary flame.
[0161] Still further, air emission openings (upstream air emission
openings) 48 are formed adjacent to the boundary between the
introduction portion 60 and the intermediate portion 61. The air
emission openings (upstream air emission openings) 48 serves to
supply air to a side of the burner port assembly, so as to
stabilize an auxiliary flame.
[0162] The first and the second face plates 11 and 12 of the air
passage member 5 each have concave and convex shapes at each
portion for forming a gap between the both plates or between each
plate and another member.
[0163] Describing successively, near the distal end, a plurality of
troughs 70 and 71 extending heightwise are formed on walls defining
the first combustion part-forming portion 62. The troughs 70 and 71
each have a concave or hollow shape in surface view and extend
heightwise in parallel. The trough 70 is shorter than the trough
71. The troughs 70 and 71 are formed mainly for strengthening the
plates.
[0164] In the present embodiment, the troughs 70 and 71 are
arranged over full width of the air passage member 5 in such a
sequence of arrangement as a plurality of the short troughs 70,
thereafter a plurality of the long troughs 71, then a plurality of
the short troughs 70, and so on.
[0165] Further, the distance between the long troughs 71 are wider
than that between the other troughs.
[0166] Concaved parts 72 each as shown in FIGS. 12 and 13 are
formed every between the long troughs 71 and adjacent to the
proximal end of the long troughs 71. The concaved parts 72 each
have also a streamline shape and a concave shape in surface view.
More specifically, the concaved parts 72 each are formed by a large
circle and a small circle with their centers displaced from each
other and a common tangent connecting the circles, the large circle
being located at upstream of the air passage and the small circle
being located at downstream of the air passage. A line connecting
the centers of the two circles is in parallel to an air flowing
direction. The common tangent connecting two circles have an
inclination angle of 30 degrees or less relative to the line
connecting the centers of the circles.
[0167] Six ribs 73 are formed, as shown in FIG. 12, on the
intermediate portion 61 of the air passage member 5. The ribs 73
each are arranged in parallel to an air flowing direction. The ribs
73 each have contact with an outer surface of the intermediate
member 6 so as to form a gap therebetween, as described below, and
have a tip (ridge), whose location (distance from the center line
of the air passage member 5) is thoroughly at the same level at any
site. Specifically, as described above, the intermediate portion 61
has a tapered cross section of the passage, but the height of the
ribs 73 (size of protuberances) increases in an inverse tapered
manner as going upward, the location of the tips being at the same
level.
[0168] A number of troughs 75 are also formed in parallel on the
introduction portion 60. The troughs 75 each extend from the
proximal end of the air passage member 5 toward the distal end and
have a concave shape in surface view.
[0169] A trough 77 extends in a transverse direction (in a
direction perpendicular to an air flow) adjacent to the
introduction portion 60.
[0170] The trough 77 is formed mainly for positioning.
[0171] A protuberance 80 of a substantially triangular shape is
formed on the central portion at each side of the air passage
member 5.
[0172] Now, the burner port assembly 3 will be described below.
Referring to FIGS. 8 and 14, the burner port assembly 3 is
constituted by a main body 25 with a decompression wall 26 welded
at its each side.
[0173] The main body 25 of the assembly 3 is also formed by a
unitary sheet steel pressed and molded into an unfolded form having
a concave and convex shape on its surface, which is bent and
connected at its periphery by means of a spot welding. The main
body 25, as shown in FIG. 14, has flanges 85 at both sides
adjoining a top face 30, being joined by the flanges 85, and a face
opposite to the top face 30 is open.
[0174] The main body 25 of the assembly 3, as shown in FIGS. 8 and
14, has the top face 30 functioning as burner ports and two side
walls 31 and 32 bent at a substantially 90 degree angle at the both
edges of the top face 30. The top face 30 of the assembly 3 has an
elongated shape with an A-line shape cross section. The top face 30
is of a roof-like shape, with a ridge portion 86 at the center
being the highest and its both sides being gradual inclined walls
87.
[0175] As described above, the burner port assembly 3 is made by
bending a piece of metal plate, which is tucked down at the ridge
portion 86 of the top face 30. Thus, as shown in the figure, the
tucked portion protrudes downward as a vertical wall 88 within a
cavity of the assembly 3.
[0176] The top face 30 of the main body 25 has slot-like openings,
which constitute burner ports (central openings) 33. Each of the
slots (burner ports 33) extends in a width direction of the top
face 30. A plurality of the slot-like openings are formed in
parallel over all area in a longitudinal direction of the top face
30. As shown in FIG. 14, a plurality of slot-like openings make up
a burner port group 89, a plurality of the burner port groups 89
being arranged at regular intervals on the top face 30.
[0177] As to a cross section of the main body 25, as shown in FIG.
8, the main body 25 has two squeezed portions 78 and 79.
Conversely, there are two protruding portions, i.e., a distal
protruding portion 90 and an intermediate protruding portion 91,
except a proximal end portion.
[0178] Specifically, the main body 25 has the distal protruding
portion 90 including the top face 30 described above and the
intermediate protruding portion 91 formed at the middle portion.
The distal squeezed portion 78 is formed between the intermediate
protruding portion 91 and the distal protruding portion 90. The
proximal squeezed portion 79 is formed adjacent to the proximal end
of the intermediate protruding portion 91.
[0179] Among the protruding portions 90 and 91 and the squeezed
portions 78 and 79 described above, the distal protruding portion
90 and the intermediate protruding portion 91 are formed over full
width of the burner port assembly 3.
[0180] Small openings 35 are formed, as shown in FIG. 14, in a row
on the side of the distal protruding portion 90.
[0181] The proximal squeezed portion 79 has a plurality of ribs 92,
as shown in FIG. 14. The ribs 92 each protrude outside in surface
view; in other words, form a trough 93 within the cavity, as shown
in FIG. 6. The ribs 92 each extend in a height direction of the
assembly 3 and are arranged in parallel in a width direction of the
assembly 3.
[0182] Open ends of the side walls 31 and 32 are, as shown in FIGS.
6, 8, 16, and 17, bent at a substantially 90 degree angle twice,
each forming outside a trough (or a gutter) 38 for engagement. The
troughs 38 have bottom walls 36 vertical to and outer walls 37
parallel to the respective side walls 31 and 32.
[0183] The outer wall 37 constituting the trough 38 has a front
view of a substantially trapezoidal shape. Specifically, the both
sides of the outer wall 37 are inclined as shown in an enlarged
view in FIG. 15 in a tapered shape. Further, as shown in FIGS. 16
and 17, the side walls 31 and 32 within the troughs 38 each have
protuberances 95. The protuberances 95 are positioned at both ends
of the trough 38, respectively; one protuberance 95 for each
end.
[0184] The decompression walls 26 are fixed to the upper ends of
the respective side walls 31 and 32 of the main body 25. The
decompression walls 26 each are, as shown in FIG. 14, an elongated
plate, covering the entire area of the distal protruding portion 90
of the main body 25. Gaps 29 are formed between the decompression
walls 26 and the respective side walls 31 and 32 of the main body
25. The gaps 29 each have an opening at a top of the figure. The
opening functions as a side opening 27. Herein, the decompression
wall 26 has, as shown in FIG. 8, a small protuberance 97 on its
inner surface, the protuberance 97 contacting with the main body 25
to maintain the distance of the side opening 27.
[0185] As described above, the openings 35 (FIG. 14) are formed in
a row on the distal protruding portion 90. The gaps 29 are
communicated with an inner space of the main body 25 via the
openings 35.
[0186] In the both ends of the main body 25, the side walls 31 and
32 are joined by a spot welding to constitute flanges 85 and have
gaps 98 therebetween from the proximal end to the vicinity of the
intermediate protruding portion 91.
[0187] Next, relationship between components will be described
below, making reference to FIGS. 5 and 6.
[0188] In the present embodiment, the premixer 2 and the burner
port assembly 3 are engaged to constitute the intermediate member
6, as well.
[0189] The burner port assembly 3 (intermediate member 6) is, as
described above, interposed between the two air passage members 5,
the top face 30 of the assembly 3 lying below (in the figure) the
top level of the air passage member 5 in the figure and, so to say,
buried between the air passage members 5. Therefore, a space ahead
of the top face 30 of the assembly 3 is partitioned by walls of the
two air passage members 5. In the present embodiment, a space
enclosed by the top face 30 of the assembly 3 and the two air
passage member 5 functions as the first combustion part 46.
[0190] The intermediate member 6 is constituted by the burner port
assembly 3 and the premixer 2 engaged therewith in such a manner as
inserting the premixer 2 with the top part 50 ahead into a cavity
of the assembly 3. At this time, the flanges 51 formed at the both
sides of the premixer 2 are engaged with the gaps 98 formed at the
both ends of the assembly 3. Then, the tips of the premixer 2 come
into contact with the innermosts of the gaps 98, respectively, and
whereby positioning in an inserting direction is done.
[0191] The vertical walls 82 formed at the lower part of the
opening row part 10 of the premixer 2 come into contact with the
inner wall of the proximal squeezed portions 79 of the assembly 3,
respectively, and whereby positioning in a thickness direction is
done.
[0192] The small area portion 58 of the opening row part 10 of the
premixer 2 comes to the position of the intermediate protruding
portion 91 of the assembly 3.
[0193] As for gaps between the opening row part 10 of the premixer
2 and the assembly 3, as described above, the small area portion 58
is situated in the intermediate protruding portion 91 of the side
walls 31 and 32 of the assembly 3. Specifically, the intermediate
protruding portion 91 corresponds to the position of the row parts
of the openings 8 of the opening row part 10. Consequently, outer
sides of the openings 8 of the row part 10 is away from the side
walls 31 and 32, thereby forming spaces (mixing spaces) 39 wider
than the other portions. The mixing spaces 39 extend over full
width corresponding to all the openings 8.
[0194] As described above, the lower part of the row part 10 of the
premixer 2 has contact with the inner walls of the proximal
squeezed portion 79 of the assembly 3. Thus, the outer walls of the
row part 10 have contact with the inner walls of the assembly 3
with no space at most sites in a width direction. However, the
proximal squeezed portion 79 has, as described above, a plurality
of ribs 92, the inner surfaces of which are the troughs 93 (FIG.
6). Consequently, the outer walls of the row part 10 are kept away
from the inner walls of the assembly 3 at the sites of the ribs 92.
Further, the ribs 92 each extend in a height direction of the
assembly 3, thereby ensuring that the mixing spaces 39 are
communicated with the proximal end of the assembly 3.
[0195] Herein, as to a positional relationship between the ribs 92
and the openings 8 formed on the row part 10 of the premixer 2, as
shown in FIG. 18, the openings 8 are situated above the ribs 92. In
other words, the openings 8 are on extensions of the ribs 92. In
the present embodiment, as shown in FIG. 18, the ribs 92 correspond
one-to-one with the openings 8, but may not correspond, as shown in
FIG. 19, in such a manner that the openings 8 are more than the
ribs 92 or vice versa.
[0196] There are gaps between the proximal end of the assembly 3
and the premixer 2. Thus, the mixing spaces 39 are communicated
with outside via the ribs 92 (troughs 93) and the above-mentioned
gaps.
[0197] On the other hand, above the mixing spaces 39, there is a
relatively large space 47 between the side walls 31 and 32 and
between the top part 50 of the row part 10 and the top face 30 of
the assembly 3. In the present embodiment, the above-mentioned
mixing spaces 39 and the space 47 at downstream of the row part 10
constitute a burner port-upstream passage 49.
[0198] Referring to FIGS. 5 and 6, the air passage members 5 are
joined with the both sides of the intermediate member 6. Each of
the air passage members 5 is secured to the intermediate member 6
by engaging the air inlet 15 at the proximal end of the member 5
with the trough 38 of the burner port assembly 3. Specifically, the
outer wall 37 of the trough 38 is inserted into the air inlet 15
and the tip of the air passage member 5 is inserted into the trough
38, and whereby the air passage member 5 is brought into contact
with the bottom wall 36 of the trough 38.
[0199] Herein, the outer wall 37 of the trough 38 is, as described
above, of a trapezoid shape in surface view and has the both sides
in a tapered shape, so that the inner wall of the air inlet 15
follows the tapered shape of the outer wall 37 of the trough 38 in
joining the air passage member 5, and whereby positioning in a
width direction is done.
[0200] When the air passage member 5 fits in a regular place in the
burner port assembly 3, as shown in FIG. 17, the protuberances 95
formed in the trough 38 engage with the outer edges of the trough
77 formed adjacent to the opening of the air passage member 5, with
a feeling of click stop.
[0201] Further, when the air passage member 5 fits in the regular
place, as shown in FIG. 24, the burner port-facing air emission
openings 23 are situated between the burner port groups 89 of the
assembly 3 in a width direction.
[0202] At the upstream end (the bottom in the figure) of the
combustion apparatus 1, the space 40 between the air passage member
5 and the intermediate member 6 is closed by the bottom wall 36 of
the trough 38. Thus, the space 40 between the air passage member 5
and the intermediate member 6 is not directly communicated with
outside at the proximal end.
[0203] As shown in FIGS. 5 and 6, the distal squeezed portion 78
comes to the side of the upstream air emission openings 48 of the
air passage member 5. The distal squeezed portion 78 is a concaved
portion of the surface of the assembly 3, so that there is a gap
between the air passage member 5 and the assembly 3 adjacent to the
upstream air emission openings 48.
[0204] Further, the gap is communicated with the first combustion
part 46. Specifically, the air passage of the air passage member 5
is tapered toward the distal end beyond the openings 48, so that
the outer wall of the air passage member 5 becomes situated to the
inward side of the air passage toward downstream, forming wider
space between the member 5 and the assembly 3. Herein, the outer
wall of the air passage member 5 and the burner port assembly 3
partly contact with each other via the ribs 73 formed on the member
5.
[0205] Now, a function of the combustion apparatus 1 will be
described below.
[0206] A number of combustion apparatuses 1 are accommodated in the
casing 54 as shown in FIG. 3 and air is sent by the fan 41 from the
bottom in the figure as shown in FIG. 4. Further, fuel gas is
introduced through the gas inlet 43 of the premixer 2 by means of a
nozzle.
[0207] Air flows in the substantially same way as the
above-mentioned embodiment, that is; air blow generated by the fan
41 is straightened through openings of a straightening vane 44
(FIG. 4) so as to be introduced into the combustion apparatus 1
through the proximal end (bottom in the figure) of the apparatus
1.
[0208] There are three routes for air introduced into the apparatus
1, as well as in the foregoing embodiment. Specifically, the first
route passes through the air passage member 5, as shown in FIG. 6,
the air blow being introduced through the air inlet 15 formed at
the proximal end of the air passage member 5 into the air passage
member 5 and going up to the distal end through the air passage 13
within the member 5. Most of the air is discharged outside through
the distal openings 20 and 21.
[0209] Herein, in the present embodiment, as shown in FIG. 20, the
distal end of the air passage member 5 is acute-angled and the
distal openings 63 and 64 among all the distal openings are slots
extending over entire heights of the inclined surfaces 16 and 17
and the top portion 9, thereby preventing air from staying in the
distal end portion or causing turbulent flow.
[0210] As shown in FIG. 21, for example, in the case that the
distal end portion of the air passage member is of a round shape,
air having introduced through the air inlet 15 bumps into a
circular surface of a ceiling to flow around the distal end portion
along the circular surface. The air flowing therearound bumps into
air flow newly supplied as indicated by arrows, resulting in
disturbing emission of newly supplied air and distorting an
emission direction. In this way, a rounded shape of the distal end
portion of the air passage member 5 generates turbulent flow or air
eddy, resulting in an unstable direction of air flow. That causes
flicker of the secondary flame. Further, according to the
experiments by the inventors, it is noisy.
[0211] On the other hand, the present embodiment has the
acute-angled distal end portion as shown in FIG. 20, thereby
ensuring less portion into which supplied air bumps and less air
flowing around the distal end portion. Further, the slot-like
openings are formed on the inclined surfaces, so that most of air
bumping into the inclined surfaces is discharged outside through
the slot-like openings. That stabilizes an emission direction of
air, causes less flicker of the secondary flame, and reduces the
noise. However, in the present invention, a shape of the distal end
of the air passage member is not limited, and may be round as shown
in FIG. 21.
[0212] In the combustion apparatus 1 of the present embodiment,
part of air flowing in the air passage member 5 is discharged also
through the combustion part-facing air emission openings 23 and the
air emission openings (upstream air emission openings) 48.
[0213] The air having been discharged through the combustion
part-facing air emission openings 23 is discharged in a direction
diagonally to the front of an axis line of the apparatus 1 from the
inclined surfaces 22 toward between the burner port groups 89 and
89 of the burner port assembly 3.
[0214] The air having been discharged through the openings
(upstream air emission openings) 48 flows in the space 40 between
the air passage member 5 and the intermediate member 6, and then
reaches the side of the burner port assembly 3. More specifically,
the air having been discharged through the openings 48 is
discharged into a gap formed by the proximal squeezed portion 78 of
the burner port assembly 3, and then flows in the space formed by
the tapered wall of the air passage member 5 to be discharged to
the side of the burner port assembly 3.
[0215] The second route passes through inside the intermediate
member 6, into which air is introduced through the openings 28 into
between the premixer 2 and the side walls 31 and 32 of the burner
port assembly 3.
[0216] This air flows through the troughs 93 (the reverse side of
the ribs 92) formed on the inner surface of the burner port
assembly 3, entering the mixing spaces 39, and then flowing into
the space 47 between the opening row part 10 and the top face 30 of
the burner port assembly 3. That is, the air described above flows
in the burner port-upstream passage 49. Finally, the air is
discharged through the slots, i.e., the burner ports (central
openings) 33, into the first combustion part 46. Part of the air
having entered the space 47 enters the gaps 29 between the main
body 25 and the side walls 31 and 32 through the openings 35 formed
on the side walls 31 and 32 of the main body 25 and is discharged
into the first combustion part 46 through the side openings 27.
[0217] Now, the third route for air will be described in detail.
The third route is a route for the primary air, which is introduced
with fuel gas through the gas inlet 43 of the premixer 2. The third
route is the same route as that of fuel gas flow, being illustrated
in the following description as that of the fuel gas flow. The fuel
gas flow is indicated by arrows in solid line.
[0218] Fuel gas is introduced into the third route with the primary
air through the gas inlet 43 of the premixer 2 to be mixed with air
in a part such as the mixing part 7, the resulting mixture flowing
into the opening row part 10. Herein, in the present embodiment,
there is no squeezed portion between the uniform cross-section
portion 57 and the opening row part 10. Thus, the fuel gas enters
the opening row part 10 without variation in flow rate in
particular.
[0219] The fuel gas having entered the row part 10 is uniformly
discharged through each opening 8. Specifically, the row part 10 is
not too small inside, thereby dissipating fine eddy generated in a
part such as an indirect passage in the premixer 2. Further, as
described above, there is no squeezed portion just before the row
part 10, so that the fuel gas introduced into the row part 10 has
small variation in flow rate over the cross section of the passage.
Therefore, the row part 10 has small variation in pressure inside,
so that the fuel gas is uniformly discharged through each opening
8. Opening diameters of the openings 8 may be narrowed down so as
to equalize jetted gas volume.
[0220] The fuel gas having been discharged through the openings 8
of the row part 10 enters the mixing spaces 39 constituted by the
intermediate protruding portion 91 of the burner port assembly 3,
so as to be mixed with air flowing in the burner port-upstream
passage 49 (including the mixing spaces 39).
[0221] The air flowing in the mixing spaces 39 flows from bottom to
top in the figure and is straightened.
[0222] Specifically, the air flowing into the mixing spaces 39,
which is introduced thereinto through the openings 28 between the
premixer 2 and the side walls 31 and 32 of the burner port assembly
3, passes through the troughs 93 (the reverse side of the ribs 92)
formed on the inner surface of the burner port assembly 3, thus
being laminar airflow.
[0223] More specifically, in the present embodiment, most portion
of the proximal squeezed portion 79 of the burner port assembly 3
has contact with the outer walls of the premixer 2, but the
proximal squeezed portion 79 has a number of troughs 93 formed on
its inner surface, thus having gaps at sites of the troughs 93.
Each trough 93 is communicated with the mixing spaces 39.
Therefore, air having introduced through the openings 28 between
the premixer 2 and the side walls 31 and 32 passes through a number
of troughs 93, then reaching the mixing spaces 39. The troughs 93
are elongated passages arranged in parallel at regular intervals,
so that the introduced air is straightened by flowing in a
plurality of troughs 93.
[0224] The air flowing in the burner port-upstream passage 49
(including the mixing spaces 39) flows in a height direction of the
apparatus 1, whereas the fuel gas having been discharged through
the openings 8 of the row part 10 flows into the mixing spaces 39
in a direction perpendicular to the air flow. Thus, the fuel gas
having been discharged through the openings 8 of the row part 10
bumps into the air also at the mixing spaces 39, so as to be
promoted to be mixed with the air.
[0225] Additionally, in the present embodiment, the openings 8 of
the row part 10 are on extensions of the troughs 93 (the reverse
side of the ribs 92), respectively, so that the air having passed
through the troughs 93 bumps into the fuel gas having been
discharged through the openings 8 more certainly.
[0226] Further, the mixing spaces 39 extend over full width of the
row part 10, thereby smoothing its pressure.
[0227] The fuel gas, which passes through the mixing spaces 39,
flows upward, and flows into a space formed by the distal
protruding portion 90, is promoted to be mixed with the air during
flowing there. Then, most of the fuel gas is discharged into the
first combustion part 46 through the slots, i.e., the burner ports
33.
[0228] The fuel gas having been discharged through the slots is
homogenous and uniform in flow rate when being discharged through
the slots because the gas is mixed with the air within the premixer
2 and further within the mixing spaces 39.
[0229] Part of the air having entered the space 47 enters the gaps
29 between the main body 25 and the side walls 31 and 32 through
the openings 35 formed on the side walls of the main body 25, then
being discharged through the side openings 27 into the first
combustion part 46.
[0230] Being ignited, fuel gas produces the primary flame in the
first combustion part 46 to perform the primary combustion.
Unburned combustible components are discharged outside through the
openings of the first combustion part 46 to perform the secondary
combustion with air supplied through the distal end portion of the
air passage member 5.
[0231] Further, in the present embodiment, air is supplied into the
proximal end of the primary flame to produce an auxiliary flame at
the proximal end of the primary flame.
[0232] In short, in the present embodiment, part of fuel gas is
discharged through the side openings 27 into the first combustion
part 46. However, the flow rate of the fuel gas discharged through
the side openings 27 is slower than that of the fuel gas discharged
through the slots. Specifically, the fuel gas enters the gaps 29
between the main body 25 and the side walls 31 and 32 through the
openings 35 formed on the side walls of the main body 25, then
being discharged through the side openings 27 into the first
combustion part 46. Therefore, the fuel gas entering the gaps 29 is
restricted in volume, and whereby gas volume discharged through the
side openings 27 is small. However, the side openings 27 each have
a large opening space, so that the fuel gas discharged through the
side openings 27 flows slowly.
[0233] Further, as described above, part of the air passing through
the air passage member 5 is supplied to the fuel gas discharged
through the side openings 27, thereby ensuring a complete
combustion.
[0234] Specifically, the air having been discharged through the air
emission openings (upstream air emission openings) 48 flows through
the gaps formed by the side walls of the air passage member 5 and
the distal squeezed portion 78 of the burner port assembly 3 along
the gaps formed by the tapered walls of the air passage member 5,
then reaching the sides of the burner port assembly 3.
[0235] A stable auxiliary flame is produced adjacent to the side
openings 27, coupled with a low flow rate of fuel gas as described
above. Thus, the proximal end of the primary flame is held by small
flames produced adjacent to the side openings 27.
[0236] Also in the present embodiment, air is diagonally supplied
through the combustion part-facing air emission openings 23 formed
on the inclined surfaces 22, thereby starting combustion of part of
unburned gas in the first combustion part 46 and producing partly a
secondary flame. This secondary flame becomes continuous with the
secondary flame outside.
[0237] Further, in the present embodiment, air is discharged to
between the burner port groups 89 of the burner port assembly 3, so
that the air is sufficiently supplied to the vicinity of the burner
port groups 89, thereby stabilizing the primary flame
certainly.
[0238] Also in the present embodiment, the air having been supplied
through the combustion part-facing air emission openings 23 does
not obstruct the primary flame or a flow of unburned gas, thereby
producing the secondary flame at a point distant from the air
passage member 5 so as not to heat the member 5 excessively.
[0239] Consequently, the combustion apparatus of the present
embodiment stabilizes the first and the second flames, being
practical.
[0240] The above-mentioned embodiment illustrates the premixer
having openings for discharging fuel gas at its side by an example.
This configuration discharges fuel gas in a direction perpendicular
to an air flow, thereby having frequent bumping of fuel gas and
air, which promotes mixture thereof.
[0241] For exerting the similar effect, such a configuration as
diagonally discharging fuel gas can be considered. As shown in FIG.
22, for example, inclined surfaces 66 and 67 of a roof-like shape
are formed on the top of a premixer 2, with slot-like openings 68.
In the present embodiment, fuel gas is discharged diagonally in
front through the slot-like openings 68. As a consequence, the fuel
gas bumps into air, so as to be promoted to be mixed with the air.
Further, the present embodiment hardly causes eddy of fuel gas or
air, thereby stabilizing fuel gas concentration.
[0242] A combustion apparatus shown in FIG. 23 has slot-like
openings 69 formed on the top of a premixer.
[0243] It is recommended to discharge fuel gas in a direction cross
to an air flow, but the present invention does not except such a
configuration as discharging fuel gas along an air flow as shown in
FIG. 23.
[0244] In the embodiments shown in the figures following after FIG.
2, each member has a number of concave and convex shapes on its
surface. The concave and convex shapes each exert not only a
function of constituting passages but also a function of improving
rigidity of each plate. The concave and convex shape not
constituting the passages only exerts the function of improving
rigidity of each plate.
[0245] In each embodiment described above, gaps between metallic
plates constitute a unitary passage. Specifically, a concave
portion is formed on one or both plates, thereby forming a gap
between the one and the other plates. Herein, it is one of design
variations to form a concaved portion or the like on either plate
in forming a passage, and the present invention is not limited to
the above-mentioned embodiments. In the above-mentioned
embodiments, for example, the second route includes a passage
passing between the inner surface of the burner port assembly 3 and
the outer peripheral surface of the premixer 2 so as to secure the
passage by forming the troughs 93 on the inner surface of the
burner port assembly 3. However, by contraries, a passage may be
constituted by forming a concaved portion or the like on the
premixer 2.
* * * * *