Information
-
Patent Grant
-
6315552
-
Patent Number
6,315,552
-
Date Filed
Friday, March 31, 200024 years ago
-
Date Issued
Tuesday, November 13, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Patnode; Patrick K.
- Cabou; Christian G.
-
CPC
-
US Classifications
Field of Search
US
- 431 278
- 431 284
- 431 285
- 431 8
- 431 354
- 239 568
- 239 555
- 239 559
- 239 567
- 239 553
- 239 5533
- 239 5535
- 239 552
- 239 549
-
International Classifications
-
Abstract
Increased turndown ratio is achieved by providing an atmospheric gas burner having a burner body with a plurality of ports formed therein and a fuel flow divider disposed in the burner body. The fuel flow divider defines a primary fuel chamber and at least one secondary fuel chamber, wherein the secondary fuel chamber is in fluid communication with at least one of the ports and the primary fuel chamber is in fluid communication with the remaining ports. A first mixing tube introduces a fuel-air mixture into the primary fuel chamber, and a second mixing tube introduces a fuel-air mixture into the secondary fuel chamber.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to atmospheric gas burners and more particularly to such burners used in domestic cooking appliances.
Atmospheric gas burners are commonly used as surface units in household gas cooking appliances. Conventional gas burners ordinarily comprise a cylindrical head having a number of ports formed around its outer circumference. A mixer tube introduces a mixture of fuel and air into the burner head. The fuel-air mixture is discharged through the ports and ignited to produce a flame. A significant factor in the performance of gas burners in general is a burner's operating range as measured by the turndown ratio (i.e., the ratio of the maximum fuel input rate to the minimum fuel input rate that will support a stable flame). Operating range is particularly important for gas burners used in gas cooking appliances because such burners are often required to operate over a wide range of inputs.
A burner's turndown ratio is limited by the minimum gas velocity at the burner ports that will support a stable flame. When fuel input is reduced for simmer operation, the gas velocity through the ports becomes lower. Eventually, the gas velocity can become so low as to result in no flame at all or a marginal flame that is prone to being extinguished by disturbances in the surroundings, such as room drafts or oven door slams. The problem is particularly evident in the so-called sealed gas burner arrangements, i.e., burner arrangements lacking an opening in the cooktop surface around the base of the burner to prevent spills from entering the area beneath the cooktop, thereby facilitating easier cleaning of the appliance. Generally, the turndown ratio for such burners with one fuel stream is limited to about 13:1.
One known burner that provides an increased turndown ratio is the dual fuel stream burner, which incorporates two separate burner bodies having individual fuel inputs. Such burners have a central burner body, which is much like a smaller version of a standard cylindrical burner head, encircled by a separate annular burner body having a larger diameter. However, the central burner body does not experience as much external air flow because it is completely surrounded by the outer burner body. Thus, less secondary combustion air is available, and the heat output of the burner is reduced. Other drawbacks of such “dual ring” burners are that they are more difficult to clean and are generally more costly than single body burners.
Accordingly, there is a need for a single body atmospheric gas burner that provides increased turndown ratio.
SUMMARY OF THE INVENTION
The above-mentioned need is met by the present invention which provides a gas burner having a burner body with a plurality of ports formed therein and a fuel flow divider disposed in the burner body. The fuel flow divider defines a primary fuel chamber and at least one secondary fuel chamber, wherein the secondary fuel chamber is in fluid communication with at least one of the ports and the primary fuel chamber is in fluid communication with the remaining ports. A first mixing tube introduces a fuel-air mixture into the primary fuel chamber, and a second mixing tube introduces a fuel-air mixture into the secondary fuel chamber.
The present invention and its advantages over the prior art will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding part of the specification. The invention, however, may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:
FIG. 1
is an exploded perspective view of an atmospheric gas burner of the present invention.
FIG. 2
is a top view of the gas burner of
FIG. 1
with its cap removed.
FIG. 3
is a cross-sectional view of the gas burner taken along line
3
—
3
of FIG.
2
.
FIG. 4
is a bottom view of the fuel flow divider from the gas burner of FIG.
1
.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,
FIGS. 1-4
show an atmospheric gas burner
10
of the present invention. The gas burner
10
is located on a support surface
12
that forms a portion of the top side of a gas cooking appliance such as a range or cooktop. As best shown in
FIG. 3
, the gas burner
10
is arranged as a so-called sealed burner. This means that there is no visible open space in the support surface
12
around the burner
10
. The area beneath the support surface is thus sealed off to prevent spills from entering, thereby facilitating cleaning of the coocking surface. However, it should be understood that the present invention is not limited to use in sealed burner appliances, but is equally applicable to other types of gas cooking appliances.
The gas burner
10
comprises a delta-shaped burner body
14
having a center region with first, second and third legs
18
,
20
,
22
radiating outward therefrom. While a delta-shaped burner body Is used as an example to facilitate disclosure of the inventive concept of the present invention, it should be recognized that the present invention is not limited to burner bodies having three legs and is applicable to burner bodies having virtually any number of legs as well as circular burner bodies. The burner body
14
includes a delta-shaped base portion
24
and a sidewall
26
formed along the periphery of the base portion
24
and extending perpendicularly therefrom. The burner body
14
may be of any construction, such as an aluminum casting, that is capable of accommodating the types of mechanical stresses, temperatures, and other operating conditions to which the gas burner
10
will be exposed. A delta-shaped cap
28
covers. the top of the burner body
14
, so that the cap
28
, the base portion
24
and the sidewall
26
define a hollow interior. The cap
28
can either be fixedly attached to the sidewall
26
or can simply rest on the sidewall
26
for easy removal.
A plurality of burner ports
30
is formed in the outer edge of the sidewall
26
so as to be in fluid communication with the burner's hollow interior. As used herein, the term “port” refers to an aperture of any shape from which a flame can be supported. The burner ports
30
are distributed around the circumference of the sidewall
26
and are typically, although not necessarily, evenly spaced. Generally, the total number of burner ports
30
will be in the range of about 15 to 36, depending on the size and heating requirements of the gas burner
10
. Although all of these ports
30
are shown in the Figures as being essentially identical, it should be noted that they may differ in configuration. Furthermore, some of the ports
30
differ in the manner in which they are supplied with fuel, as will be described in detail below.
Although not shown in the drawings, the burner body
14
can also include a plurality of carry over slots formed in the outer edge of the sidewall
26
. The carry over slots are relatively shallow slots formed between adjacent ones of the ports
30
to improve the flame retention and stability of the burner
10
. These carry over slots are described in more detail in U.S. Pat. No. 5,899,681, issued May 4, 1999 to James R. Maughan.
As seen best in
FIG. 3
, a primary mixing tube
32
, such as a venturi tube, extends axially through the support surface
12
so as to have one end (the inlet end) located externally of the burner body
14
, below the support surface
12
, and the other end (the delivery end) connected to an opening in the base portion
24
so as to provide an entrance to the interior of the burner body
14
. The primary mixing tube
32
is shown to be centered in the center region of the burner body
14
, although it can alternatively be located off center as well. A primary fuel nozzle
34
is located approximately concentric with the mixing tube
32
and has an injection orifice
36
aligned with the inlet end of the primary mixing tube
32
so that fuel discharged from the injection orifice
36
flows into the mixing tube
32
. Primary air to support combustion is obtained from the ambient space around the burner
10
(typically from below the burner
10
) and is entrained by the fuel jet in conventional fashion through the open area around the inlet end of the primary mixing tube
32
. Thus, the mixing tube
32
introduces a primary fuel-air mixture into the interior of the burner body
14
.
A secondary mixing tube
38
, such as a venturi tube, extends axially through the support surface
12
and the base portion
24
so as to have one end (the inlet end) located externally of the burner body
14
, below the support surface
12
, and the other end (the delivery end) located in the interior of the burner body
14
. Alternatively, the delivery end may be flush with the base portion
24
. The secondary mixing tube
38
is located adjacent to the primary mixing tube
32
. As shown in the Figures, the secondary mixing tube
38
is at the first leg
18
of the burner body
14
, although other locations are possible. A secondary fuel nozzle
40
is located approximately concentric with the secondary mixing tube
38
and has an injection orifice
42
aligned with the inlet end of the secondary mixing tube
38
so that fuel discharged from the injection orifice
42
flows into the secondary mixing tube
38
. Primary air to support combustion is obtained from the ambient space around the burner
10
(typically from below the burner
10
) and is entrained by the fuel jet in conventional fashion through the open area around the inlet end of the secondary mixing tube
38
. Thus, the secondary mixing tube
38
introduces a secondary fuel-air mixture into the interior of the burner body
14
.
A fuel flow divider
44
is disposed inside the burner body
14
. The fuel flow divider
44
is shaped so as to direct fuel from the secondary mixing tube
38
to selected ports
30
. In the illustrative embodiment, the fuel flow divider
44
is a delta-shaped member having first, second and third diffuser sections
46
,
48
,
50
for the primary fuel air mixture arranged around a center region. The first, second and third diffuser sections
46
,
48
,
50
of the fuel flow divider
44
are aligned with, but shorter than, the corresponding first, second and third legs
18
,
20
,
22
of the burner body
14
. An inlet conduit
54
extends through the center of the. fuel flow divider
44
and is coaxially aligned with the primary mixing tube
32
. Thus, the fuel-air mixture introduced via the primary mixing tube
32
is directed into the burner body interior surrounding the fuel flow divider
44
, hereinafter referred to as the primary fuel chamber
56
.
The fuel flow divider
44
also includes three C-shaped enclosures
58
,
60
,
62
formed between adjacent ones of the first, second and third diffuser sections
46
,
48
,
50
. Each enclosure
58
,
60
,
62
extends above the upper surface of the fuel flow divider
44
into engagement with the underside of the cap
28
. Each enclosure
58
,
60
,
62
includes a pair of laterally spaced ridges
64
that extend outward from the sides of the fuel flow divider
44
and are received in slots formed in the inner surface of the sidewall
26
. Thus, each enclosure
58
,
60
,
62
cooperates with the base portion
24
, the sidewall
26
and the cap
28
to define first, second and third secondary fuel chambers
66
,
68
,
70
, respectively that are each isolated from the primary fuel chamber
56
. Although three enclosures and three diffuser sections are shown by way of example, it should be understood that the number of these elements is not limited to three. Furthermore, it is not required that the number of enclosures and the number of diffuser sections be the same.
Each of the secondary fuel chambers
66
,
68
,
70
is in fluid communication with a corresponding one of the burner ports
30
. However, it should be noted that each of the secondary fuel chambers
66
,
68
,
70
could be in fluid communication with more than one of the ports
30
. The remaining burner ports
30
(i.e., any one of the ports
30
not in fluid communication with one of the secondary fuel chambers
66
,
68
,
70
) are in fluid communication with the primary fuel chamber
56
.
As best seen in
FIG. 4
, the underside of the fuel flow divider
44
(i.e., the side facing the base portion
24
) has a series of cavities and channels formed therein that define a passageway for directing the fuel-air mixture introduced via the secondary mixing tube
38
to the secondary fuel chambers
66
,
68
,
70
. Specifically, first, second and third cavities
72
,
74
,
76
are formed the bottom side of the distal ends of the first, second and third diffuser sections
46
,
48
,
50
, respectively. The delivery end of the secondary mixing tube
38
is located in the first cavity
72
. An annular channel
78
encircles the inlet conduit
54
, and first, second and third openings
80
,
82
,
84
provide fluid communication between the annular channel
78
and the first, second and third cavities
72
,
74
,
76
, respectively. The second cavity
74
has two apertures
86
and
88
that provide fluid communication with the first and second secondary fuel chambers
66
and
68
, respectively, and the third cavity
76
has an aperture
90
that provides fluid communication with the third secondary fuel chamber
70
. Alternatively, the second secondary fuel chamber
68
could be provided with fuel via an aperture in the third cavity
76
instead of the second cavity
74
.
Thus, the fuel flow divider
44
defines two distinct fuel flow circuits having no significant leakage therebetween. In the first circuit in which the primary fuel-air mixture flows from the primary mixing tube
32
, through the inlet conduit
54
, and into the primary fuel chamber
56
. The upper surface of the fuel flow divider
44
, which forms a gap with the cap
28
, approximates a cylindrical diffuser for the fuel-air mixture. The primary fuel-air mixture is discharged through the burner ports
30
that are in fluid communication with the primary fuel chamber
56
(i.e., the primary ports) for combustion. Combustion is initiated by a conventional igniter, such as a spark ignition electrode (not shown), located adjacent to one of the burner ports
30
.
In the second circuit, the secondary mixing tube
38
delivers the secondary fuel-air mixture into the first cavity
72
. From there, the secondary fuel-air mixture flows through the first opening
80
into the annular channel
78
and then through the second and third openings
82
and
84
into the second and third cavities
74
and
76
, respectively. The fuel-air mixture in the second cavity
74
passes through the first aperture
86
into the first secondary fuel chamber
66
and through the'second aperture
88
into the second secondary fuel chamber
68
. The fuel-air mixture in the third cavity
76
passes through the third aperture
90
into the third secondary fuel chamber
70
. The secondary fuel-air mixture from each secondary fuel chamber
66
,
68
,
70
is discharged through the corresponding burner port
30
that is in fluid communication therewith (i.e., the secondary ports) for combustion.
As shown in the Figures, there are twenty-seven primary ports and three secondary ports, thereby providing a 10:1 ratio of total burner ports to secondary ports. While the present invention is not necessarily limited to this port ratio, the number of secondary ports will be considerably less than the number of primary ports.
The primary fuel nozzle
34
is connected to a source of gas
92
via a first valve
94
, and the secondary fuel nozzle
40
is connected to the source of gas
92
via a second valve
96
(shown schematically in FIG.
3
). Both valves
94
and
96
are jointly controlled in a known manner by a control knob on the gas cooking appliance to regulate the flow of gas from the source
92
to the two fuel nozzles
34
and
40
. The range of operation of the valves
94
and
96
is as follows. When the control knob is turned wide open, the first valve
94
supplies fuel at maximum pressure to the primary fuel nozzle
34
, and the second valve
96
supplies fuel at maximum pressure to the secondary fuel nozzle
40
. As the knob is turned down, the fuel pressure to the primary fuel nozzle
34
is gradually reduced until such point that a minimum pressure for a sustainable flame is reached. Over this range, the fuel supplied to the secondary fuel nozzle
40
from the second valve
96
can either be constant or vary as the knob is turned down. Upon further turndown from the above-mentioned point that a minimum pressure for a sustainable flame is reached, the first valve
94
remains closed so that no fuel is supplied to the primary fuel nozzle
34
, and the fuel pressure to the secondary fuel nozzle
40
is gradually reduced until the burner
10
is turned off.
For regular operation, the valves
94
and
96
are adjusted by manipulating the control knob so that fuel is directed to the primary and secondary fuel nozzles
34
and
40
. This fuel is discharged from the respective injection orifices
36
and
42
, entrains air for combustion, and enters the corresponding mixing tubes
32
and
38
. The fuel-air mixture from the primary mixing lube
32
flows through the inlet conduit
54
and into the primary fuel chamber
56
. From there, the primary fuel-air mixture is discharged through the primary ports for combustion. The fuel-air mixture from the secondary mixing tube
38
flows into the first cavity
72
and follows the flow paths described above into the secondary fuel chambers
66
,
68
,
70
. From there, the secondary fuel-air mixture is discharged through the secondary ports for combustion. Thus, all thirty burner ports
30
support a flame during regular operation.
For simmer or extended turndown operation, the control knob is adjusted so that fuel is directed to the secondary fuel nozzle
40
only. As before, this fuel is discharged from the secondary injection orifice
42
, entrains air for combustion, and flows through the secondary mixing tube
38
into the first cavity
72
. The secondary mixture than flows into the secondary fuel chambers
66
,
68
,
70
and is discharged through the secondary ports for combustion. Thus, during simmer operation only the three secondary ports support a flame. Accordingly, because the ratio of total burner ports to secondary ports is 10:1, the turndown ratio over the entire range of burner operation will be increased ten times over that turndown ratio available for regular operation. For example, if the gas burner
10
could support a turndown ratio of 10:1 during regular operation, then it would have a turndown ratio of 100:1 over its entire range of operation.
An ancillary benefit of the present invention is that the flames supported by the secondary ports (i.e., those of the ports
30
that are on the secondary fuel circuit) tend to be more resistant to transient disturbances, such as door slams, which tend to extinguish flames in conventional burners. This is because the secondary fuel chambers
66
,
68
,
70
and the cavities
74
and
76
act as flow disturbance dampers due to their relatively large volumes adjacent to the port and with restricted access to the supply circuit. Thus, the secondary port flames will be able to withstand transient disturbances that extinguish the primary port flames and will subsequently serve as a reignition source for the primary ports after the disturbance has passed. Additionally, the secondary ports are positioned in the burner body to make them less susceptible to drafts.
The foregoing has described a single body gas burner having an extended turndown ratio. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims
- 1. A gas burner comprising:a burner body having center region with a plurality of legs radiating outward therefrom and having a plurality of ports formed therein; a fuel flow divider having center region with a plurality of diffuser sections radiating outward therefrom, said fuel flow divider being disposed in said burner body so that each one of said diffuser sections is located in a corresponding one of said burner body legs, said fuel flow divider defining a primary fuel chamber and a plurality of secondary fuel chambers, wherein each one of said secondary fuel chambers is in fluid communication with a separate set of at least one of said plurality of ports and said primary fuel chamber is in fluid communication with the remaining ones of said plurality of ports; a primary mixing tube for introducing a fuel-air mixture into said primary fuel chamber; and a secondary mixing tube for introducing a fuel-air mixture into said secondary fuel chambers.
- 2. The gas burner of claim 1 wherein said secondary fuel chambers are isolated from said primary fuel chamber.
- 3. The gas burner of claim 1 wherein said fuel flow divider includes a inlet conduit that is aligned with said primary mixing tube and is in fluid communication with said primary fuel chamber.
- 4. The gas burner of claim 3 wherein said fuel flow divider has a passageway formed in its underside, said passageway comprising:a cavity formed in the distal end of each one of said diffuser sections, one end of said secondary mixing tube being located in a first one of said cavities; an annular channel encircling said inlet conduit, said annular channel being in fluid communication with each one of said cavities; a first aperture between a second one of said cavities and a first one of said secondary fuel chambers; a second aperture between a second one of said cavities and a second one of said secondary fuel chambers; and a third aperture between a third one of said cavities and a third one of said secondary fuel chambers.
- 5. The gas burner of claim 4 wherein said inlet conduit is centered in said center region of said fuel flow divider.
- 6. The gas burner of claim 1 wherein said fuel flow divider includes a plurality of enclosures formed thereon, said enclosures cooperating with said burner body to define said secondary fuel chambers.
- 7. The gas burner of claim 6 wherein each one of said enclosures includes a pair of outwardly extending ridges that engage said burner body.
US Referenced Citations (3)
Foreign Referenced Citations (6)
Number |
Date |
Country |
0719982-A |
Dec 1995 |
EP |
633234 |
Jun 1927 |
FR |
631072 |
Dec 1927 |
FR |
481578 |
Jun 1936 |
GB |
0370326 |
Oct 1974 |
GB |
11-223310 |
Aug 1990 |
JP |