U.S. patent number 3,633,562 [Application Number 05/023,838] was granted by the patent office on 1972-01-11 for slightly pressurized flat-top stove.
This patent grant is currently assigned to Columbia Gas Service Corporation. Invention is credited to William F. Morse, Edward A. Reid, Jr..
United States Patent |
3,633,562 |
Morse , et al. |
January 11, 1972 |
SLIGHTLY PRESSURIZED FLAT-TOP STOVE
Abstract
A kitchen range having a smooth top of heat-resistant glass,
beneath which there are infrared gas burners. Heating is by
infrared radiation and conduction through the glass top. The
products of combustion are exhausted through an outlet at the rear
of the range. Its burners are positioned within a closed chamber
into which a small blower directs air so as to produce a slightly
elevated air pressure.
Inventors: |
Morse; William F. (Upper
Arlington, OH), Reid, Jr.; Edward A. (North Columbus,
OH) |
Assignee: |
Columbia Gas Service
Corporation (New York, NY)
|
Family
ID: |
21817503 |
Appl.
No.: |
05/023,838 |
Filed: |
March 30, 1970 |
Current U.S.
Class: |
126/39J;
126/214R |
Current CPC
Class: |
F24C
3/047 (20130101) |
Current International
Class: |
F24C
3/04 (20060101); F24C 3/00 (20060101); F24c
003/06 (); F24c 015/10 () |
Field of
Search: |
;126/39,39J,214
;431/328,329 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myhre; Charles J.
Claims
What is claimed is:
1. In a gas range, the combination of, a shell construction forming
a closed chamber, a pair of grill assemblies mounted in said shell
respectively defining an air inlet and an air outlet therein, a gas
burner unit positioned within said chamber, said burner unit
comprising means forming a plenum chamber and a hot gas chamber, a
burner element closing the top of said plenum chamber, and forming
the bottom of said hot gas chamber and adapted to produce infrared
radiation when said burner unit is ignited, a plate of heat
resistant glass which transmits infrared radiation and transmits
heat by conduction, said plate having a bottom surface extending
over the top of said hot gas chamber, thereby to confine the hot
gases in said hot gas chamber from flowing upwardly, means
providing a hot gas discharge passageway from said hot gas chamber
to said air outlet to discharge said hot gases from said range,
blower means for supplying air to said closed chamber to maintain
an air pressure therein greater than atmospheric pressure, said
grill assemblies being adapted to restrict the flow of air
therethrough thereby to maintain said air pressure within said
closed chamber at a pressure slightly elevated above atmospheric
pressure, and an air and combustible gas supply assembly comprising
a supply duct operatively connected at one end to said plenum
chamber and having a flared open end in said closed chamber and a
gas discharge nozzle located in spaced relation to and
substantially coaxially of said flared open end, said supply duct
and said discharge nozzle defining a venturi assembly whereby gas
discharged from said nozzle entrains pressurized air in said
chamber and is projected with said entrained air through said duct
to said plenum chamber
2. A gas range as described in claim 1 wherein one of said grill
assemblies is located along a front edge of said shell construction
forming said air inlet, and the other of said grill assemblies
providing said air outlet is located at the side of said shell
assembly opposite to said front side and opens upwardly of said
shell, and wherein said means providing a hot discharge passageway
projects the hot gases upwardly through said air outlet.
3. A gas range as described in claim 2 wherein said shell
construction and said gas burner unit are formed of sheet
material.
4. A gas range as described in claim 2 which includes a plurality
of said burner units and said means providing a gas discharge
passageway and a corresponding number of said air and gas supply
assemblies.
Description
This invention relates to gas ranges or stoves of the flattop type,
and more in particular to stoves of the type shown in U.S. Pat. No.
3,470,862, which utilize infrared radiant heating.
It is an object of the present invention to provide improved gas
ranges of the general type of the one disclosed in the
above-identified patent. Another object is to provide improved
control for gas burners of the type shown in the above-identified
patent. These and other objects will be in part obvious and in part
pointed out below.
In the drawing:
FIG. 1 is a perspective view with parts broken away of one
embodiment of the invention;
FIG. 2 is a fragmentary top plan view of the embodiment of FIG. 1;
and
FIG. 3 is a sectional view on line 3--3 of FIG. 2.
Referring to FIG. 1 of the drawing, a flattop, gas-fired cooking
range or stove 2 has four burner units 4, 6, 8 and 10. Each of the
burner units is formed by an integral sheet material assembly 12
(see also FIG. 3) which is supported in a sheet metal traylike
shell 14. Shell 14 has a bottom wall 16 (see also FIG. 2), a rear
wall 18, sidewalls 20 and a front structure 22. Structure 22
includes a horizontal top strip 28 and a bottom strip 27, both of
sheet metal, and a vertical front panel 24. Strip 28 is attached at
its ends to the sidewall 20, and at its rear edge there is an angle
strip forming a ledge 29. The angle strip also extends along the
sides of the shell where it is attached to the tops of the
sidewalls. At the rear of the shell there is an air outlet grill 26
which rest upon an angle strip 31 attached to wall 18 and a cross
strip 33 which provides a supporting ledge and which also provides
an extension of ledge 29.
Resting upon ledge 29 is a plate 30 of heat-resistant glass which
has its top surface flush with the top surface of shell 14 and
grill 26. Plate 30 provides a removable closure for the top of the
shell and forms a closed chamber 31, with there being the air
outlet grill 26 at the rear through which hot gases and air are
exhausted. Each of the burner units 4, 6, 8 and 10 has an annular
flange 35 which is in alignment with ledge 29 so that plate 30
presses tightly against the flange, and effectively closes the top
of the burner unit. As will be more fully discussed below, plate 30
transmits infrared radiation very effectively, and during use it is
heated to a relatively high temperature. Hence, the disc portion
above each burner unit provides a smooth cooking surface upon which
utensils or materials may be placed to be heated by the combined
action of infrared radiation heating and conduction heating.
As shown at the upper left-hand corner of FIG. 2, a small blower 60
is mounted in front panel 24 so as to draw air through a grill 66
from the front of the range into the chamber 31 formed by shell 14
and plate 30. Blower 60 has an electric motor 62 which is energized
automatically whenever any of the burner units is turned on. Blower
60 does not produce a substantial air pressure, but delivers a
sufficient volume of air to chamber 31 to maintain a slightly
pressurized condition therein. As is discussed below, this slightly
pressurized air is utilized by the burner units in a manner to give
greatly improved results. Grill 26 permits the excess air to
discharge from the chamber, but the grill provides sufficient
resistance to maintain the desired air pressure in the chamber. The
elevated air pressure around the burner units creates a tendency
for the air to leak into the units. The excess air flows past the
burner units so as to cool the exposed surfaces, and it is then
discharged upwardly through grill 26.
Each of the burner units has a plenum chamber 36 at the bottom to
which a mixture of gas and air is delivered through a tangential
supply duct 38. A plurality of adjustable angle bracket assemblies
45, mounted on the bottom of shell 14, support the burner
assemblies. The upper portion of the burner unit is enlarged to
provide an annular ledge 39 upon which rests a wire mesh infrared
burner element 41. Burner element 41 provides a combustion surface
throughout the top of the cylindrical plenum chamber 36. Above
burner element 41 the cylindrical hot gas chamber 43 provides a
heating zone from which the infrared radiation and the heat of
conduction pass through the disc portion of plate 30.
Mounted in the sidewall of plenum chamber 36 is a tangential supply
duct 38 which has a flared open end 40. Spaced from and aligned
with the open end 40 of the duct is a gas supply valve 42 which
receives gas from a supply pipe 48, and which has a control knob 44
and a gas discharge nozzle 46 mounted in front panel 24. Gas from
the valve is discharged horizontally toward the flared open end 40
of its duct 38, thus forming a venturi assembly by which the gas
entrains the desired amount of the slightly pressurized fresh air
from chamber 31 for proper combustion. The turning of the knob 44
to open a valve 42 also energizes the blower motor 60 and an
ignitor 49 for that burner mounted in ledge 39 above the burner
surface so as to ignite the burner. The burner element 41 is of a
wire mesh which produces infrared radiation when the burner unit is
ignited.
Extending rearwardly from each of the hot gas chambers 43 is a
rectangular gas outlet duct 50 which terminates beneath grill 26
and has a top gas outlet opening 52, and an end wall 54 which
deflects the gas upwardly through the grill. Hence, when a burner
unit is operating, the hot gases are discharged through opening 52,
and there is sufficient jet effect to cause a circulation of fresh
air at grill 26 so that the fresh air mixes with the hot gases and
dilutes the hot gases and reduces the temperature of the air
passing upwardly from the grill. As indicated above, the
circulation of the air through shell 14 prevents excessive heating
of the walls of the burner units. That characteristic is very
important, particularly with ranges or stoves for domestic and
general usage. Normally, when air at atmospheric pressure is
aspirated by the jet of gas, there are limitations upon the limits
on reducing the heating effect of the burner. Special arrangements
may be provided for overcoming this difficulty. However, with the
present invention, the difficulty is overcome by the simple
procedure of producing a slightly pressurized air condition in
chamber 31. That gives additional beneficial effects as discussed
above. It also insures the proper exhausting of the products of
combustion from the burner units. The pressurized air condition in
chamber 31 insures the entrainment of air with the gas even at very
low gas flow rates. Hence, the burners may be modulated throughout
a very wise range of heating rates.
When a burner unit is ignited, the infrared radiation is
transmitted through the disc portion 56 of plate 30, which is the
portion or zone of the plate directly above the burner unit and is
defined by flange 35. Disc portion 56 is also heated primarily by
conduction from the hot gases in chamber 43, but there is some
heating by the infrared radiation. In this embodiment, this disc
portion 56 of an ignited burner unit is heated to a temperature of
the order of 1,000.degree. to 1,100.degree. F. A utensil or other
material placed upon the disc portion 56 is heated by the combined
and direct action of both the infrared radiation from the burner
element 41 and the heating by the disc portion 56. The by disc
portion 56 may be primarily by direct conduction, but there is also
substantial radiation from the disc portion.
As indicated above, plate 30 is a heat resistant glass, and it has
a very low heat-transfer factor. Hence, while the disc portion 56
is at a very high temperature, there is negligible transfer of heat
horizontally along plate 30 beyond the edge of disc portion 56,
i.e., at flange 35. Therefore, plate 30 remains at substantially
room temperature except for the specific areas or portions which
are heated by the ignited burner units. It has been pointed out
above that the gases which are discharged from an ignited burner
produce a jet effect which causes hot gases and fresh air to mix
and pass upwardly through and from grill 26. That circulation of
fresh air through chamber 31 assists in maintaining the room
temperature condition of the portions of plate 30 which are not
directly above the various burner units.
This tangential duct arrangement for delivering the air-gas mixture
to the plenum chamber aids in providing a satisfactory pattern of
gas-air flow and distribution within the plenum chamber to insure
uniform combustion and infrared radiation throughout the combustion
surface of the unit. The products of combustion pass horizontally
from the hot gas chamber 43 of a burner at a relatively slow rate
of flow. That permits the gases to heat the disc portion 56 and
then to pass rearwardly, as explained above.
* * * * *