Note: Descriptions are shown in the official language in which they were submitted.
CA 02538558 2006-03-03
Attorney Docket 2004P01013US
DIFFUSION PLATE AND GRATE ASSEMBLY FOR A GAS BURNER
FIELD OF THE INVENTION
(O1 ) The present invention relates to a combination gas burner and grate
assembly with
a diffusion burner plate assembled therewith for limiting heat transfer to a
cooking utensil
such as a pot when the burner is operating at low intensity levels. This
arrangement
eliminates hot spots typically created by low intensity level burners, while
having little to
no effect on heat transfer at high intensity levels.
BACKGROUND OF THE INVENTION
(02) Current cooktops employing gas burners have been used commercially and
residentially for a number of years. As the construction of such cooktops,
both as
standalone, built-in, slide-in or drop-in cooktop appliances as well as a part
of free
standing ranges has evolved, the amount of energy generated by such cooktops
has
increased, both when employed at the lowest burner intensity settings, as well
as at the
highest burner intensity settings. In fact, cooktops designed for residential
use today are
approaching the capabilities of commercial units, including generation of the
high BTU's
possible with such commercial units. This has led to a number of problems when
burners
on such cooktops are used at lower intensity levels, or at the lowest
intensity levels, for
example, for simmering food items in cooking utensils such as pots.
(03) More specifically, the problem with the use of such burners at low
intensity levels
is that there is not a uniform distribution of energy due to relatively short
flame length
and thus, this generally creates selected hot spots in the cooking utensil
while attempting
specialized cooking operations such as simmering. As a result, simmering does
not occur
uniformly and portions of the food being cooked may tend to burn or to be
cooked
excessively, while other portions are not sufficiently cooked.
(04) In the past, numerous attempts have been made to distribute the energy
from gas
burners in a more uniform manner. One attempt to do so involves placing a
diffuser plate
directly on the grate with which a burner is used so that the flames coming
from the
burner are not allowed to contact the cooking utensil. Such an approach avails
itself of
the fact that heating of the cooking utensil occurs by conduction which occurs
as a result
of the flames impinging on the diffuser plate and causing heat to be conducted
through
CA 02538558 2006-03-03
Attorney Docket 2004P01013US
the diffuser plate to the cooking utensil. This approach is suitable for a low
burner flame
operation, but is not suitable for a high flame operation.
(OS) More specifically, if the diffuser plate is made too thick and is
separated
sufficiently from the burner as a result of being placed above the grate,
there may be
insufficient energy transfer to the cooking utensil when the burner is
operated at low
intensity levels. Conversely, if the diffuser plate is made too thin, due to
the imperfect
nature of how heating of the diffuser plate and conduction occurs, there could
still result a
number of localized hotspots, which also occur when a diffuser plate is not
used. More
specifically, depending on materials selected for the diffuser plate,
conduction is
generally not uniform. While there may be materials from which the diffuser
plate could
be made in which conduction could more evenly occur, such materials would make
construction of the diffuser plate prohibitively expensive.
(06) One alternative approach has been to provide a jet impingement/radiation
plate
which functions to transfer heat from a burner to a cooking utensil both by
radiation and
by jets produced by jet holes in the plate. Such a plate is generally mounted
directly
below a grate of a burner and while attempting to create radiant heat, still
has the
problems of creating hotspots particularly because conduction occurs from the
plate to the
grate directly and therefrom to the cooking utensil. Similarly, the fact that
hot
combustion products, i.e., burning gas, pass through the many openings in the
plate to
impinge upon the bottom of the cooking utensil also causes the problem of
localized
hotspots.
(07) Other approaches have involved various deflector arrangements in an
attempt to
enlarge the area of flame impinging on cooking utensil. All of these
approaches suffer
from the afore-mentioned problems.
(08) These and other problems of the prior art are avoided in accordance with
the
present invention in which a system is provided for limiting heat transferred
to a cooking
utensil when a burner is operating at low intensity levels, and providing
heating at the
lower intensity levels substantially through radiation with little or
substantially no
conduction occurring, while having little or no effect on heat transfer when
the burner is
operated at high intensity levels.
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Attorney Docket 2004P01013US
BRIEF SUMMARY OF THE INVENTION
(09) In accordance with one aspect of the invention, there is provided a gas
burner and
grate combination, which includes a gas burner constructed for being operated
at least at
a high intensity level and at a low intensity level. As will be appreciated by
those of
ordinary skill in the art, such burners are also capable of being operated at
intermediate
levels between the highest and the lowest intensity level depending on the
amount of
opening of a valve providing gas to the burner.
(10) A grate is located in association with the gas burner for supporting a
cooking
utensil thereon and for having food therein cooked through operation of the
gas burner.
Such a cooking utensil can take various forms including pots, pans and various
other
containers for food. A diffusion burner plate is located above the gas burner
at a location
for being spaced from a cooking utensil when a cooking utensil is positioned
on the grate.
The diffusion burner plate is of a size such that when the gas burner is
operated at a high
intensity or at levels, which are higher than the lowest intensity level as
appropriate, the
flame length is long enough to reach beyond the diffuser burner plate. When
the gas
burner is operated at a low intensity level, i.e., typically at the lowest
intensity level and
selected levels higher than the lowest level, depending on the size selected
for the diffuser
burner plate, the flame is contained under the diffusion burner plate and
heating of the
cooking utensil occurs substantially by radiation. This avoids hot spots,
which occur at
low intensity levels. Alternately, there can be a central opening or hole in
the diffusion
burner plate which can provide both radiation and a controllable amount of
heat transfer
directly to the cooking vessel through the central opening.
( 11 ) The diffusion burner plate can be constructed integral to the grate or
with means
for being removably attached to the grate such as, for example, with clips.
The
removably attached diffusion burner plate can be utilized with burners that
were not
originally fitted or made with a diffusion burner plate. Further the diffusion
burner plate
can just loosely rest on fingers provided on the grate, so the diffusion
burner plate easily
can be lifted off of the grate for cleaning.
( 12) The diffusion burner plate can be constructed in various forms to
conform to the
shape of the burner or to be different from the shape of the burner. The
diffusion burner
plate can be made of metal or a ceramic material and can be of different
shapes such as
concave or convex. For example, in the case of a star shaped burner the
diffusion burner
plate can be star shaped or circular. The diffusion burner plate can also be
perforated, but
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Attorney Docket 2004PO10I3US
not sufficiently to allow flames to reach through the burner plate to the
cooking utensil,
with the exception of ones designed with the central opening therein.
(13) In a yet still further aspect, the invention relates to a cooktop, which
includes at
least one gas burner and grate combination with a diffusion burner plate as
previously
described. The cooktop preferably includes a plurality of gas burners and a
corresponding plurality of grates, or a single large grate, corresponding to
the plurality of
burners and with at least one diffusion burner plate on one of the gas burner
and grate
assemblies. In a yet still further aspect, the cooktop can include a plurality
of diffusion
burner plates corresponding to the plurality of gas burners. By the term
plurality is meant
at least two, and in most typical cooktop constructions, at least four and in
some cases six
to eight aforementioned combinations.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
( 14) Fig. 1 is a perspective view of the gas burner and grate combination
illustrating
the diffuser burner plate of the present invention mounted thereon;
(15) Fig. 2 is a top plan view of the gas burner and grate combination of Fig.
1;
(16) Fig. 3 is a side partial cross-sectional view of the gas burner and grate
combination of Fig. 1 showing the diffusion burner plate with the gas burner
in operation;
(17) Fig. 4 is a side partial cross-sectional side view of the gas burner and
grate
combination showing for illustration purposes only the diffusion burner plate
operating as
one half of the operation and with the other half without the diffusion burner
plate, both
with the gas burner in operation;
(18) Fig. 5 is a side partial cross-sectional view of the gas burner and grate
combination showing another embodiment of the diffusion burner plate with a
central
opening and with the gas burner in operation;
(19) Fig. 6 is a side partial cross-sectional view of an alternate embodiment
in which
the diffusion burner plate is removably mounted to the grate by a plurality of
clips; and
(20) Fig. 7 is perspective view of a cooktop having multiple gas burners and
illustrating a pair of gas burner and grate combinations, each with a
diffusion burner plate
of the present invention mounted thereon.
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CA 02538558 2006-03-03
Attorney Docket 2004P01013US
DETAILED DISCUSSION OF THE INVENTION
(21 ) Figs. 1 and 2 illustrate a gas burner and grate combination 11 in
accordance with
the present invention. A gas burner 13 is associated with a cooking utensil
support such
as a grate 15, as conventionally used on gas cooktops, as is well known by
those of
ordinary skill in the art. A diffusion burner plate 17 is disposed between the
gas burner
13 and the grate 15 and attached to the grate 1 S. The diffusion burner plate
17 is sized or
dimensioned so that gas flames (see Fig. 3) emanating through apertures 19 of
the gas
burner 13, when the burner 13 is operated at the lowest or lower intensity
levels, will not
extend beyond a peripheral edge 20 of the diffusion burner plate 17 and
instead will
impinge directly on the bottom of the diffusion burner plate 17 to achieve
radiant heating
of a cooking utensil such as a pot which may be placed on the grate 15 (see
Fig 3),
without any substantial amount of conduction of heat to the cooking utensil.
By the term
lowest or lower intensity levels is meant low heat or the approximate lowest
flame
intensity for the burner 13 to maintain.
(22) Fig. 3 illustrates one embodiment of the present invention and its
operation at both
high fire 23 on the left and low fire 21 on the right. This operation is only
for purposes of
illustration as the gas burner 13 in normal operation emits a substantially
uniform flame
around a periphery 22 thereof. In this Figure, the diffusion burner plate 17
is directly
connected to the grate 15, preferably below or at the lowest level of the
grate 15 so as to
create an air gap 27 between the diffusion burner plate 17 and the cooking
utensil 25.
When the gas burner 13 is turned on at the lowest or a low intensity level
(low fire
illustrated on the right side of Fig. 3), the flames 21 resulting from gas
discharged
through the ports 19 are contained beneath the diffusion burner plate 17.
Heating of the
cooking utensil 25 occurs as a result of conduction 29 which heats up the
diffusion burner
plate 17 to cause heat 31 to radiate through the air gap 27 up to the cooking
utensil 25 to
promote substantially uniform heating, substantially without hotspots of the
cooking
utensil 25. When the gas burner 13 is turned onto a high or higher intensity
level (high
fire illustrated on the left side of Fig. 3), the length of the flames extend
as flames 23
beyond the edge 20 of the diffusion burner plate 17 and therefore the
diffusion burner
plate 17 does not interfere with direct heating 34 of the cooking utensil 25
at the higher
intensity levels. By the term high or higher intensity level is meant high
heat or the
approximate highest flame intensity for the burner 13 to maintain in a normal
operation.
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Attorney Docket 2004P01013US
(23) It will be appreciated that some conduction 29 occurs through the grate
15 to the
diffusion burner plate 17 as a result of the diffusion burner plate 17 being
directly
attached thereto, but this is a substantially minimal effect.
(24) In the embodiment of Fig. 3, and Figs. 1 and 2, the diffusion burner
plate 17 is
shown permanently mounted to the grate 15 by any means appropriate as will be
readily
apparent to those of ordinary skill in the art. The diffusion burner plate 17
can be
permanently mounted to the grate 15 by numerous methods, such as welding,
mechanical
fasteners, such as screws or rivets or a mechanical interlocking feature like
a bayonet
twist. The diffusion burner plate 17 also can be integrally made or formed
with the grate
15, such as by casting.
(25) In accordance with Fig. 4, for illustration purposes only, the diffusion
burner plate
17 is illustrated operating as one half of the operation 30 (left side) and
with the other half
of the operation 32 (right side) a standard burner operation without the
diffusion burner
platel7, both with the gas burnerl3 in a simmer operation producing the low
flame 21. In
the diffusion burner plate 17 operation 30, heat 36 from the flames 21 is
convectively
transferred to the diffusion burner plate 17, which in turn radiates heat 31
from the
diffusion burner plate 17 to the utensil 25. In the standard operation 32,
heat 38 from the
flames 21 is convectively transferred directly to the utensil 25, with minimal
conductive
heat loss. Both operations 30 and 32 have minimal conductive heat loss into
the grate 15.
(26) In accordance with Fig. 5, another embodiment of the present invention is
illustrated, in this case, the diffusion burner plate 17' includes a central
opening 33. The
central opening 33 is dimensioned to provide some direct connective heat
transfer
through the diffusion burner plate 17' to the utensil 25. This may enhance the
heating of
a central portion 35 of the utensil 25 and also can reduce the weight of the
diffusion
burner plate 17'.
(27) Although the diffusion burner plates 17, 17' have been described as being
attached permanently or substantially permanently to the grate 15, the
diffusion burner
plates 17, 17' also can be separate from the grate 15 and can just rest on the
grate 15.
This also is illustrated in Fig. 5, where the diffusion burner plate 17' is a
separate element
and rests on a plurality of fingers or lips 42 which are secured to or formed
with the grate
15. The fingers 42 can be welded or integrally formed with the grate 15.
Although not
illustrated, the diffusion burner plate 17' also could have projections formed
thereon
which allow the diffusion burner plate 17' to rest on the grate 15. In that
case the grate
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Attorney Docket 2004P01013US
15 would not be formed with the fingers 42. In either case, the diffusion
burner plate 17'
easily can be removed from the grate 15 just by lifting the diffusion burner
plate 17' off
of the grate 15, such as for cleaning purposes.
(28) In accordance with Fig. 6, an alternative construction of the present
invention is
shown, in this case, the diffusion burner plate 17 is mounted onto the grate
15 by way of a
plurality of clips 33 which can allow for removal of the diffusion burner
plate 17 in
selected instances as may be appropriate for the user. Also the clips 33 allow
the
diffusion burner plate 17 to be added to cooktops to which it was not provided
for as a
retrofitting of the cooktop. While the clips 33 are illustrated, as will be
readily apparent
to those of ordinary skill in the art, other equivalent means for mounting the
diffusion
burner plate 17 can be employed. What is important is that the air gap 27
between the
diffusion burner plate 17 and the bottom of any utensil 25 placed on the grate
15 is
maintained. Further the air gap 27 is sized to provide the most efficient
radiant heating of
utensils 25 at low intensity levels of operation of the gas burner 13. The air
gap 27 and
the diameter of the diffusion burner plate 17 are optimized for the diameter
of specific
burners 13, BTU rate, the design of the burner ports 19, type of fuel, etc.
Generally the
diameter of the diffusion burner plate 17 is the most critical factor as long
as the air gap
27 is present. Generally an air gap 27 on the order of at least two (2) to
three (3)
millimeters is sufficient for operation with the diffusion burner plate 17.
The upper limit
of the air gap 27 depends upon the desired operation of the cooktop and the
type of
burner utilized.
(29) In a yet still further aspect of the present invention, there is shown in
Fig. 6 a
cooktop 37 having multiple gas burners 13 thereon and a single integral grate
15 used for
all the gas burners 13. Such a cooktop 37, as previously described, can be a
standalone
cooktop with the burners 13 mounted in a cabinet (not illustrated), or can be
part of a
combination standalone range with an oven (not illustrated). Typically, such
cooktops
include at least four burners and in some cases up to six or eight burners.
The cooktop 37
can be assembled with only one diffusion burner plate 17 or with multiple
diffusion
burner plates 17 either removably attached or permanently affixed thereto as
previously
described.
(30) As implemented, the diffusion burner plate 17 of the present invention
reduces the
net effect of energy transfer to the cooking utensil 25 when a gas burner 13
is operated at
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Attorney Docket 2004P01013US
low intensity levels without substantially reducing the net energy transfer
when the gas
burner 13 is operated at high intensity levels.
(31) As previously discussed, the diffusion burner plate 17 does not come into
contact
with the cooking utensil 25 so that heat transferred to the utensil 25 is
substantially only
by radiation from the diffusion burner plate 17 without substantial conduction
transfer.
As a result, hot spots typically found on low intensity settings of the
cooktop are avoided
by even distribution of the energy over a larger surface of the cooking
utensil 25.
(32) In various alternative constructions, the diffusion burner plate 17, 17'
can be
perforated as previously discussed. The diffusion burner plate 17, 17' can be
thick or thin
in design as will be readily apparent to those of ordinary skill in the art,
and optimized for
operation with a selected cooktop and/or gas burner and grate combination with
which it
is to be used. In terms of shape, the diffusion burner plate 17, 17' can be
substantially
flat, convex or concave in shape as appropriate to optimize performance.
Another
advantage of the use of the diffusion burner plate 17, 17' is the operation is
independent
of the type of gas burner utilized.
(33) In terms of material utilized to make the diffusion burner plate 17, it
can be made
from metal or from ceramic or from other appropriate material as will be
readily apparent
to those of ordinary skill in the art. The diffusion plate burner 17 diameter
may be
optimized in size to allow a range of settings for the lower intensity
settings for the gas
burner 13. The diffusion burner plate 17 can conform to the shape of the gas
burner 13
with which it is used or can be of a different shape. lFor example, a round
gas burner 13
may have a round diffusion burner plate 17 and a star shaped gas burner 13 may
have a
star shaped diffusion burner plate 17. In other cases the diffusion burner
plate does not
conform to the shape of the gas burner 13, for example, a round gas burner 13
could have
a star shaped diffusion burner plate 17. Other examples of shapes include
triangles or
squares. Any of shapes of the diffusion burner plate 17 can include the
central aperature
33.
(34) Having thus generally described the invention, the same will become
better
understood from the appended claims in which it is set forth in a non-limiting
manner.
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