U.S. patent number RE40,290 [Application Number 10/732,889] was granted by the patent office on 2008-05-06 for holding or cooking oven.
This patent grant is currently assigned to Duke Manufacturing Company. Invention is credited to Clement J. Luebke, Steven M. Shei.
United States Patent |
RE40,290 |
Shei , et al. |
May 6, 2008 |
Holding or cooking oven
Abstract
An oven for maintaining cooked foods at temperatures suitable
for serving the foods or even for cooking foods has a cabinet
containing multiple heat sinks of channel-shaped configuration. The
ends of the heat sinks open out of the cabinet, so that any heat
sink may receive a tray of food from either the front or back of
the cabinet. .[.The interior surface of the heat sinks generally
conform to the cross-sectional shapes of the trays, so that the
heat sinks lie along the bottoms and sides of the trays. The heat
sinks have a heating elements extended along their sides and
bottoms for elevating the temperature of the heat sinks and
directing heat into the trays within the heat sinks. In addition,
each heat sink also contains a cover which may close the top of the
tray in the heat sink and thereby retard the escape of moisture
from the tray or may vent the interior of the tray..]. .Iadd.In
other embodiments, the oven includes a cabinet having a plurality
of compartments therein, and a plurality of trays in the
compartments, each compartment being sized for receiving only one
tray per compartment. The compartments are isolated from one
another in the cabinet whereby flavor from food in one tray in one
compartment is prevented from transferring to food in trays in
adjacent compartments..Iaddend.
Inventors: |
Shei; Steven M. (Fort Wayne,
IN), Luebke; Clement J. (Hudson, FL) |
Assignee: |
Duke Manufacturing Company (St.
Louis, MO)
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Family
ID: |
26961364 |
Appl.
No.: |
10/732,889 |
Filed: |
December 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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09756941 |
Jul 17, 2001 |
6262394 |
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09538761 |
Jan 16, 2001 |
6175099 |
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09282313 |
Mar 31, 1999 |
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Reissue of: |
09906866 |
Jul 17, 2001 |
06541739 |
Apr 1, 2003 |
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Current U.S.
Class: |
219/399; 219/385;
219/394; 99/483 |
Current CPC
Class: |
A47J
39/006 (20130101) |
Current International
Class: |
A47J
36/24 (20060101); F24C 7/04 (20060101); F27B
5/02 (20060101) |
Field of
Search: |
;219/214,385,394,399,428
;99/483 ;222/146.5 ;220/345.1,351 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Pelham; Joseph
Attorney, Agent or Firm: Senniger Powers
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of application Ser. No.
09/756,941, filed Jan. 9, 2001 (on which U.S. Pat. No. 6,262,394
will issue on Jul. 17, 2001), which is a division of application
Ser. No. 09/538,761, filed Mar. 30, 2000, (on which U.S. Pat. No.
6,175,099 issued on Jan. 16, 2001), which is a continuation-in-part
of application Ser. No. 09/282,313 filed Mar. 31, 1999, (now
abandoned).
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
Claims
What is claimed is:
1. In combination with a heating device and with a tray located
within the heating device and having a rim that is presented
upwardly around the interior of the tray, a self-supporting cover
for establishing at least a partial closure over the rim of the
tray, said cover comprising: first and second legs in an upright
orientation and having lower margins for supporting the cover, the
legs being spaced far enough apart to receive the rim of the tray
between them; and a cross wall attached to the legs above their
lower margins and extending between the legs, the space between the
legs and below the cross wall being open at at least one end of the
cover, so that the rim of the tray may be inserted between the legs
and below the cross wall at that end of the cover.
2. The combination according to claim 1 wherein the legs also have
upper margins, and the cover is attached to the legs intermediate
the upper and lower margins of the legs.
3. The combination according to claim 1 wherein the space between
the legs and below the cross wall is open at both ends of the
cover.
4. The combination according to claim 1 wherein the cross wall,
where space between the legs and below the cross wall is open,
flares upwardly.
5. The combination according to claim 1 wherein the rim of the tray
is generally rectangular, having ends and sides, with the sides
being longer then the ends; and wherein the sides of the rim on the
tray are located along the legs of the cover.
6. The combination according to claim 1 wherein the legs of the
cover also have upper margins; and wherein the cross wall is
attached to each leg intermediate the upper and lower margins for
the leg, but closer to one of such margins than the other.
7. The combination according to claim 1 wherein the cross wall of
the cover contains at least one opening for venting the interior of
the tray.
8. The combination according to claim 7 wherein the cover further
includes a slide that moves along the cross wall of the cover
between a closed position in which the opening is closed and open
positions in which the opening is exposed.
9. The combination according to claim 1 wherein the cross wall of
the cover contains a plurality of openings arranged in a row; and
wherein the cover further includes a slide which is located along
the cross wall and has openings also arranged in a row, the slide
being movable along the cross wall between a closed position and
open positions, the slide when in its closed position covering the
openings in the cross wall and when in its open positions at least
partially exposing the openings in the cross wall through the
openings in the slide.
10. In combination according to claim 1 wherein the cross wall of
the cover contains a plurality of openings sized for venting
moisture from the tray.
11. In combination with a heat sink having shoulders and a tray
located within the heat sink, a cover for at least partially
closing the tray while the tray is in the heat sink, said cover
comprising: upright legs which are located over the shoulders of
the heat sink and project upwardly away from the shoulders; and a
cross wall extending between the legs and the tray.
12. The combination according to claim 11 wherein the legs of the
cover are located beyond the rim on the tray.
13. The combination according to claim 11 wherein the legs of the
cover are located beyond the rim on the tray and rest on the
shoulders of the heat sink, whereby the tray at its nm is between
the legs of the cover.
14. The combination according to claim 11 wherein the legs of the
cover have lower margins and the cover is attached to the legs
above their lower margins; and wherein the space between the legs
and below the cover is open at at least one end of the cover so
that the tray at its rim may be inserted into and removed from the
space below the cross wall on the cover.
15. The combination according to claim 14 wherein the legs have
upper margins, and the cross wall is attached to the legs below the
upper margins.
16. The combination according to claim 15 wherein the spacing
between the upper margins and the cross wall differs from the
spacing between the lower margins and the cross wall.
17. The combination according to claim 11 wherein the cross wall of
the cover contains at least one opening.
18. The combination according to claim 17 wherein the cover further
includes a slide that moves along the cross wall of the cover
between a closed position in which the opening is closed and open
positions in which the opening is exposed.
19. The combination according to claim 11 wherein the cross wall of
the cover contains a plurality of openings arranged in a row; and
wherein the cover further includes a slide which is located along
the cross wall and has openings also arranged in a row, the slide
being movable along the cross wall between a closed position and
open positions, the slide when in its closed position covering the
openings in the cross wall and when in its open position at least
partially exposing the openings in the cross wall through the
openings in the slide.
20. An oven comprising: a cabinet; a plurality of trays adapted to
be inserted in the cabinet and withdrawn from the cabinet, each
tray having a bottom wall, side walls extending upwardly from the
bottom wall, and an open top; self-supporting covers in the cabinet
for respective trays, each cover having a generally horizontal
cross wall and a pair of side walls extending downwardly from the
cross wall at opposite sides of the cross wall, said cross wall
having a width which exceeds the width of a respective tray to
allow the tray to be positioned in the cabinet between the side
walls of the cover with the cross wall extending over the open top
of the tray; each cover being releasably retained in the cabinet
against withdrawal from the cabinet when a respective tray is
removed from between the side walls of the cover and withdrawn from
the cabinet, the side walls of the cover supporting the cover in
the cabinet after the tray has been withdrawn from the cabinet; and
a heating element positioned in the cabinet to direct heat into
trays in the cabinet.
21. An oven as set forth in claim 20 wherein the cross wall of at
least one cover has at least one opening in it to vent a tray
located beneath the cover.
22. An oven comprising: a cabinet; horizontal shoulders in the
cabinet; a plurality of trays adapted to be inserted in the cabinet
and withdrawn from the cabinet, each tray having a bottom wall,
side walls extending upwardly from the bottom wall, and an open
top; covers in the cabinet for respective trays, each cover having
a generally horizontal cross wall and a pair of side walls
extending downwardly from the cross wall at opposite sides of the
cross wall over respective horizontal shoulders in the cabinet,
said cross wall having a width which exceeds the width of a
respective tray to allow the tray to be positioned in the cabinet
between the side walls of the cover with the cross wall extending
over the open top of the tray; each cover being releasably retained
in the cabinet against withdrawal from the cabinet when a
respective tray is removed from between the side walls of the cover
and withdrawn from the cabinet, the side walls of the cover resting
on said respective shoulders after the tray has been withdrawn from
the cabinet; and at least one opening in the cross wall of at least
one of said covers for venting the cover.
.Iadd.23. An oven comprising a cabinet having a plurality of
compartments therein, a plurality of trays in said compartments,
eash compartment being sized for receiving only one tray per
compartment, said compartments being isolated from one another in
said cabinet whereby flavor from food in one tray in one
compartment is prevented from transferring to food in trays in
adjacent compartments, each compartment having open ends for
placement of said tray in the compartment and removal of said tray
from the compartment, and a plurality of heaters, each heater being
operable for heating a respective compartment..Iaddend.
.Iadd.24. The oven as set forth in claim 23 wherein each
compartment has a bottom wall heated by a respective
heater..Iaddend.
.Iadd.25. The oven as set forth in claim 24 wherein each
compartment has side walls, and wherein said bottom and side walls
of each compartment are formed by a unitary member..Iaddend.
.Iadd.26. The oven as set forth in claim 25 wherein said unitary
member is generally U-shaped..Iaddend.
.Iadd.27. The oven as set forth in claim 25 wherein said unitary
member is a metal heat sink..Iaddend.
.Iadd.28. The oven as set forth in claim 23 further comprising a
cover in at least one of said compartments for covering a tray in
the compartment..Iaddend.
.Iadd.29. The oven as set forth in claim 28 wherein said cover is a
rigid cover supported in a position over the tray..Iaddend.
.Iadd.30. The oven as set forth in claim 29 wherein said cover
comprises a generally horizontal cross wall spanning the top of the
tray..Iaddend.
.Iadd.31. The oven as set forth in claim 30 wherein said cover
comprises a pair of side walls extending vertically from the cross
wall at opposite sides of the cross wall..Iaddend.
.Iadd.32. The oven as set forth in claim 29 wherein said at least
one compartment has side walls with shoulders for supporting said
cover over the tray in the compartment..Iaddend.
.Iadd.33. The oven as set forth in claim 32 wherein the side walls
of said at least one compartment are spaced apart approximately 1
inch greater than a width of said respective tray..Iaddend.
.Iadd.34. The oven as set forth in claim 23 wherein said heaters
also heat side walls of the compartments..Iaddend.
.Iadd.35. The oven as set forth in claim 23 further comprising a
control for controlling the operation of the heaters..Iaddend.
.Iadd.36. The oven as set forth in claim 35 wherein said control
controls the operation of at least one group of heaters
independently of another group of heaters..Iaddend.
.Iadd.37. The oven as set forth in claim 35 wherein said control
controls the operation of each heater independently of the other
heaters..Iaddend.
.Iadd.38. An oven as set forth in claimm 23 wherein said plurality
of compartments includes side-by-side compartments..Iaddend.
.Iadd.39. An oven comprising a cabinet having a plurality of
compartments therein, a plurality of trays in said compartments,
each compartment being sized for receiving only one tray per
compartment, said compartments being isolated from one another in
said cabinet whereby flavor from food in one tray in one
compartment is prevented from transferring to food in trays in
adjacent compartments, each compartment having open ends for
placement of said tray in the compartment and removal of said tray
from the compartment, a plurality of heaters for heating said
plurality of compartments, the operation of each of said plurality
of heaters being controlled independently of the other
heaters..Iaddend.
.Iadd.40. An oven as set forth in claim 39 wherein each of said
plurality of compartments has one of said plurality of heaters
adjacent thereto for heating the compartment..Iaddend.
.Iadd.41. An oven as set forth in claim 40 further comprising a
cover in at least one of said plurality of compartments for
covering a tray in the compartment..Iaddend.
.Iadd.42. An oven as set forth in claim 41 wherein said at least
one of said plurality of compartments has side walls with shoulders
for supporting said cover over a tray in the
compartment..Iaddend.
.Iadd.43. An oven as set forth in claim 39 wherein said plurality
of compartments includes side-by-side compartments..Iaddend.
.Iadd.44. An oven comprising a cabinet having a plurality of
compartments therein, a plurality of trays in said compartments,
each compartment being sized for receiving only one tray per
compartment, said compartments being isolated from one another in
said cabinet whereby flavor from food in one tray in one
compartment is prevented from transferring to food in trays in
adjacent compartments, each compartment having open ends for
placement of said tray in the compartment and removal of said tray
from the compartment, a plurality of heaters for heating said
plurality of compartments, each compartment being heated by one of
said plurality of heaters located adjacent the compartment, the
operation of at least one group of said plurality of heaters being
controlled independently of another group of said plurality of
heaters, and a cover in at least one of said plurality of
compartments for covering a tray in the compartment..Iaddend.
.Iadd.45. An oven as set forth in claim 44 wherein said at least
one of said plurality of compartments has side walls with shoulders
for supporting said cover over a tray in the
compartment..Iaddend.
.Iadd.46. An oven as set forth in claim 44 wherein said plurality
of compartments includes side-by-side compartments. .Iaddend.An
oven as set forth in claim 42 wherein said at least one of said
plurality of compartments has side walls with shoulders for
supporting said cover over a tray in the compartment.
Description
BACKGROUND OF THE INVENTION
This invention relates in general to ovens and more particularly to
an oven for maintaining foods at temperatures suitable for serving
or even for cooking foods.
Most restaurants which specialize in serving cooked food
rapidly--indeed, essentially with the placement of an order--do not
have the capacity to prepare large quantities of food on demand.
Thus, traditional meal times, particularly the noon hour, place
severe demands on these restaurants. Typically, the so-called "fast
food" restaurant will prepare some cooked food in advance of a meal
time and keep that food warm in a holding oven. Then, during a meal
time when the demand is greatest, it will use the food previously
cooked.
Some cooked foods, such as hamburger patties, should be held at
elevated temperatures only in a moist environment, since these
foods, when depleted of their moisture content have poor taste and
texture. Other cooked foods, such as breaded chicken or fish
fillets, should be stored such that moisture may escape, so that
they remain crisp. While it is convenient to store different foods
at the same location, the flavor of one food should not transfer to
another food. Moreover, irrespective of the food, the temperature
at which it is stored must remain high enough to prevent bacterial
contamination, and this generally requires holding the food at
temperatures in excess of about 150.degree. F. Holding ovens that
are currently in use in fast food restaurants do not fully satisfy
these requirements.
The holding ovens of current manufacture accept trays containing
the cooked foods. The typical oven has a cabinet containing storage
spaces which are accessible from both the front and rear of the
cabinet, so that a tray containing cooked food may be placed into a
storage space at one face of the cabinet and withdrawn at the other
face. Each storage space has a heated platen along its top and also
preferably at its bottom, and these platens transfer heat to the
trays. The cabinet also contains a mechanism for closing the upper
ends of the trays to prevent moisture from escaping. In one type of
holding oven this mechanism resides in making the spacing between a
heated platen on which the tray rests and the heated platen which
overlies the tray about equal to the height of the tray, so that
the upper margin of the tray lies along and essentially against the
overlaying platen, thus in effect closing the tray. See U.S. Pat.
No. 5,724,886. Another type of holding oven supports the tray on a
resilient grate which urges a tray upwardly against an overlying
heated platen, thereby effecting a seal with the overlying platen.
See U.S. Pat. No. 5,783,803. These ovens are difficult to clean and
do not efficiently concentrate the heat at the trays where it is
needed. As a consequence, the food is often held at a temperature
less than optimum. Sometimes, the spaces in these ovens hold trays
with their tops open and this leads to a transfer of flavors
between multiple trays in any one space. In any event, ovens of
current manufacture have the capacity to store foods for only very
limited periods of time.
BRIEF SUMMARY OF THE INVENTION
The present invention resides in an oven having a channel-shaped
heat sink which is heated by a heater. The heat sink has a storage
cavity which generally conforms to the shape of a tray or other
food container received in the cavity. As such, the heat sink
concentrates the heat generated by the heater at the tray so as to
efficiently maintain the food in the tray at a temperature suitable
for serving. The heat sink may have a cover for closing the top of
the tray within it. Where the oven contains multiple heat sinks,
these heat sinks are isolated from each other to prevent the flavor
of the food in one from transferring to food in another.
.Iadd.In another aspect, this invention is directed to an oven
comprising a cabinet having a plurality of compartments therein,
and a plurality of trays in the compartments, each compartment
being sized for receiving only one tray per compartment. The
compartments are isolated from one another in the cabinet whereby
flavor from food in one tray in one compartment is prevented from
transferring to food in trays in adjacent compartments. Each
compartment has open ends for placement of the tray in the
compartment and removal of the tray from the compartment. The oven
also includes a plurality of heaters, each heater being operable
for heating a respective compartment..Iaddend.
.Iadd.In another aspect, this invention is directed to an oven
comprising a cabinet having a plurality of compartments therein,
and a plurality of trays in the compartments, each compartment
being sized for receiving only one tray per compartment. The
compartments are isolated from one another in the cabinet whereby
flavor from food in one tray in one compartment is prevented from
transferring to food in trays in adjacent compartments. Each
compartment has open ends for placement of the tray in the
compartment and removal of the tray from the compartment. The oven
also includes a plurality of heaters for heating the plurality of
compartments, the operation of each of the plurality of heaters
being controlled independently of the other heaters..Iaddend.
.Iadd.In another aspect, this invention is directed to an oven
comprising a cabinet having a plurality of compartments therein,
and a plurality of trays in the compartments, each compartment
being sized for receiving only one tray per compartment. The
compartments are isolated from one another in the cabinet whereby
flavor from food in one tray in one compartment is prevented from
transferring to food in trays in adjacent compartments. Each
compartment has open ends for placement of the tray in the
compartment and removal of the tray from the compartment. The oven
also includes a plurality of heaters for heating the plurality of
compartments, each compartment being heated by one of said
plurality of heaters located adjacent the compartment. The
operation of at least one group of the plurality of heaters is
controlled independently of another group of the plurality of
heaters. A cover is provided in at least one of the plurality of
compartments for covering a tray in the compartment..Iaddend.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
In the accompanying drawings which form part of the specification
and wherein like numerals and letters refer to like parts wherever
they occur:
FIG. 1 is a front and top perspective view of a holding oven
constructed in accordance with and embodying the present invention,
with one of the covers and one of its trays shown removed;
FIG. 2 is a top and rear perspective view of the oven;
FIG. 3 is a transverse sectional view of two heat sinks, one having
its cover in its sealing position and the other having its cover in
the venting position;
FIG. 4 is a fragmentary sectional view taken along line 4--4 of
FIG. 3;
FIG. 5 is an exploded perspective view of a heat sink, the cover
for the heat sink, and a tray;
FIG. 6 is a perspective view of a modified cover.
FIG. 7 is an exploded perspective view of the heat sink, a modified
cover for the heat sink, and a modified tray; and
FIG. 8 is a fragmentary longitudinal sectional view of the modified
tray of FIG. 7 fitted beneath the modified cover of FIG. 7.
Corresponding reference numerals will be used throughout the
several figures of the drawings.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, an oven A (FIGS 1 & 2) holds
multiple trays B in which precooked food is placed and held for
limited times, indeed, several hours in the case of some foods. The
oven A and the trays B, which are used with it, will accommodate a
variety of foods typical of those served in fast food restaurants.
Among those foods are cooked hamburger patties, ham, bacon,
sausage, onion rings, French toast, fish fillets, chicken fillets
and biscuits. Thus, the trays B constitute food containers. The
oven A heats the trays B from their bottoms as well as their sides.
Moreover, one who places a tray B in the oven A has the option of
closing the top of the tray B so as to retain moisture in the tray
B or leaving the top open so that moisture may escape from the tray
B.
Considering the trays B first, they are preferably molded from a
polymer that is capable of withstanding the temperatures maintained
in the oven A, although trays B of stamped metal will suffice as
well. In any event, such a tray B has (FIGS. 3-5) a flat bottom
wall 2 and also side walls 4 and end walls 6 that merge with the
bottom wall 2 at corners 8 of generous radius. The side walls 4 and
end walls 6 flare outwardly slightly and each has an offset portion
10 near its upper end. The offset portions 10 of the walls 4 and 6,
along their upper margins, merge into a rim in the form of a
peripheral lip 14 which projects laterally outwardly and, beyond
the side walls 4, turns slightly downwardly at a depressed edge 16
(FIG. 3). The lip 14 has a flat upper surface 18 that lies in a
common plane along the entirety of the lip 14. At the end walls 6
the lip 14 merges into handles 20 which lie below the plane of the
upper surface 18. Similar trays see widespread use in fast food
restaurants.
The oven A includes (FIGS. 1 & 2) a cabinet 26 having a front
panel 28, a rear panel 30, end panels 32, and a top panel 34. The
front panel 28 and rear panel 30 contain openings 36 which conform
generally to the cross-sectional configuration of the trays B, but
are slightly wider and somewhat taller. The openings 36 are
arranged in several tiers, and for every opening 36 in the front
panel 28 an opening 36 in the rear panel 30 aligns with it. The
cabinet 26 at each tier of openings 36 also has (FIGS. 3 and 4), an
upper pan 38 that extends through it above the openings 36 and a
lower pan 40 that extends through it below the openings 36. The
upper pan 38 has a peripheral lip 41 which projects upwardly and
imparts rigidity to the pan 38. The pan 38 carries channels 42
which extend between the front and rear panels 28 and 30 in the
regions between the openings 36. More channels 42 lie beyond the
two endmost openings 36 as well. The channels 42 are attached
firmly to the pan 38 and open downwardly. The lower pan 40 for each
tier has lips 43 that project upwardly and turn inwardly and,
beneath the inwardly turned portions, has rigidifying members 44.
The space between the upper and lower pans 38 and 40 for each tier
of openings 36 is occupied by several heat sinks 46--one for each
pair of aligned openings 36 in the tier.
Each heat sink 46 is formed from a substance that conducts heat
well, aluminum being preferred. When formed from aluminum, the heat
sinks 46 may be produced as extrusions or castings or they may even
be produced by machining. Irrespective of how it is produced, each
heat sink 46 possesses (FIG. 5) a channel-like configuration in
that it is open at both ends and at its top and closed along its
two sides and bottom. This leaves the heat sink 46 with a cavity 48
that extends the full length of the heat sink 46. The open ends of
the cavity 48 align with openings 36 in the front and rear panels
28 and 30 of the cabinet 26, so that the cavity 48 of the heat sink
46 is easily accessible from the exterior of the oven A. The cavity
48 generally conforms to the exterior cross-sectional configuration
of any tray B.
More specifically, each heat sink 46 includes (FIGS. 3 & 5) a
bottom wall 50 and side walls 52 which are formed integral with the
bottom wall 50 and project upwardly from it. The bottom wall 50 is
of uniform thickness, it being about 3/16 in. thick, and has a flat
bottom surface 54 and a flat top surface 56. In contrast, the two
side walls 52, while being mirror images of each other, have
somewhat varied thickness. Each side wall 52 has a lower region 58
that generally corresponds in height to the height of a tray B. The
lower region 58 has a flat outside surface 60 and a contoured
inside surface 62 that merges with the flat top surface 56 of the
bottom wall 50 at a curved corner 64. Immediately above the corner
64, the inside surface 62 flares outwardly slightly, then after
undergoing a more abrupt change in direction, extends vertically
for a lesser distance. The spacing between the inside surfaces 62
for the side walls 52 of the heat sink 46 is slightly greater than
the width of the tray B measured across of the outside surfaces of
its side walls 4. Moreover, the inside surfaces 62 of the side
walls 52 on the heat sink 46 generally conform in configuration to
the outside surfaces for the side walls 4 of the tray B. When the
tray B is inserted into the heat sink 46 with the bottom wall 2 of
the tray B resting in the flat top surface 56 of the bottom wall 50
for the heat sink 46, the side walls 4 of the tray B, despite their
contoured configuration, are close to the inside surfaces 62 on the
side walls 52 of the heat sink 46. Generally, the spacing at any
elevation between the inside surfaces 56 on side walls 52 of the
heat sink 46 should be no more than about 1.0 in. larger than the
spacing between the side walls 4 of the tray B at the outside
surfaces of those side walls 4. Thus, when the tray B is centered
in the cavity 48 of the heat sink 46, a clearance of no more than
about 0.5 in. exists between the inside surfaces 62 of the side
walls 52 for the heat sink 46 and the outside surfaces in the side
walls 4 of the tray B. Preferably, when the tray B is centered, the
clearance is about 0.015 in. The curved corners 64, where the flat
bottom surface 54 and contoured inside surfaces 62 of the heat sink
46 merge, lie opposite, yet close to, the corners 8 of the tray
B.
The lower region 58 of each side wall 52 for the heat sink 46
merges into an upper region 66 at an offset 68. The upper regions
66 extend vertically and by reason of the offsets 68, the spacing
between the upper regions 66 exceeds the spacing between the lower
regions 58. Indeed, that spacing exceeds the width of the tray B at
its peripheral lip 14. The contoured inside surfaces 62 on the
lower regions 58 of the side walls 52 rise to flat horizontal
shoulders 70 which extend over the offsets 68 and out to the upper
regions 66. The shoulders 70 lie in a plane that is parallel to the
top surface 56 of the bottom wall 52, and the distance between the
shoulders 70 and the top surface 56 is slightly less than the
distance between the lower surface of the bottom wall 2 for the
tray B and the undersurface of the lip 14 at the side walls 4 which
undersurface is at the depressed edge 16. Thus, when the tray B
rests on the bottom wall 2 of the heat sink 44, the depressed edge
16 of the lip 14 beyond each side wall 4 lies slightly above the
shoulders 70. The lip 14 remains well below the upper edges of side
walls 52 for the heat sink 46.
Those upper edges lie along the upper regions 66 of the side walls
52 for the heat sink 46, and here the upper regions 66 are enlarged
slightly and received in the channels 42 that are attached to the
upper pan 38 for the tier in which the heat sink 46 lies (FIG. 3).
The bottom wall 50 of the heat sink 46 at its ends rests on the
inwardly turned portions of the lips 43 for the lower pan 40. (FIG.
4) to which it is fastened. Thus, the heat sinks 46 for any tier
are captured between the upper and lower pans 38 and 40 for the
tier. The channels 42 confine the heat sinks 46 of the tier
laterally, whereas the front and rear panels 28 and 30 confine them
longitudinally. In short, the heat sinks 46 are fixed in position
in the cabinet 26.
Each heat sink 46 is fitted with a heater which may take the form
of a flexible heating element 76 of the electrical resistance type.
It extends almost the full length of the heat sink 44, covering the
flat bottom surface 54 of the bottom wall 50, the corners between
the bottom wall 50 and side walls 52, and the flat outside surfaces
60 on the lower regions 58 of the side walls 52. It even curves
outwardly along the bottom surfaces of the offsets 68 in the side
walls 52. To these surfaces, the heating element 76, which is
preferably film-etched, is bonded, preferably with a silicone
adhesive capable of withstanding the elevated temperatures produced
by the heating element 76. In this regard, the heating element 76
should produce enough heat and reach a temperature high enough to
elevate the temperature of the heat sink 46 along the top surface
56 of its bottom wall 50 and along the contoured inside surface 62
of its side walls 52 to a temperature suitable for maintaining food
within the tray B that occupies that heat sink 46 at any desired
temperature. Where the oven A serves as a holding oven, that
temperature keeps the food warm enough for serving and warm enough
to prevent bacterial contamination. Where the oven A functions as a
cooking oven, that temperature is hot enough to actually cook the
food.
Other types of heaters may be used as well. For example, the heater
may take the form of resistance type heating rods embedded in the
bottom wall 50 and in the lower regions 58 of the side walls 52.
Steam or hot water may be circulated through channels in the bottom
wall 50 and lower regions 58 of the side walls 52 to maintain the
heat sink 46 at an elevated temperature, in which case the channels
and the fluid that flows within them become the heater. On the
other hand, if the heat sink 46 is formed from a ferrous material,
an induction heating device may be used to elevate the
temperature.
Behind the side walls 52 of each heat sink 46 and beneath its
bottom wall 50, as well, the cabinet 26 is packed thermal
insulation 78. The lower pans 40 in the cabinet 26 support the
insulation 78 and prevent the insulation 78 for any one tier of
heat sinks 46 from dropping into the heat sinks 46 of the tier
below.
In addition to its heating element 78, each heat sink 46 is
equipped with a cover 80 that rests on the shoulders 70 of its
offsets 68 and generally occupies the space between the upper
regions 66 of its side walls 52. The cover 80 includes a pair of
vertical legs 82 and a cross wall 84 that extends between and is
attached to the vertical legs 82. Indeed, the cross wall 84 is
joined to the vertical legs 82 between the longitudinal edges of
the legs 82, it being offset closer to one longitudinal edge of
each leg 82 than the other. However, near its ends the cross wall
84 flares away from the edges to which it is closest. The width of
the cross wall 84 slightly exceeds the width of the tray B at its
lip 14. The height of the vertical legs 82 is slightly less than
the height of the upper regions 66 of the two side walls 52 for the
heat sink 44. These dimensions enable one to easily slide the cover
80 into and out of the upper region of its heat sink 44.
The configuration of the cover 80 is such that it may assume two
positions within the space between the upper regions 66 of the side
walls 52 for the heat sink 44--a closing position (FIG. 3-left) and
a venting position (FIG. 3-right). In the closing position the
cross wall 84 of the cover 80 rests on the upper surface 18 of the
lip 14 of the tray B, or else lies slightly above the upper surface
18 of the lip 14. In either arrangement the cross wall 84 serves as
a closure for the tray B. Where the cross wall 84 actually rests on
the lip 14 the legs 82 project downwardly almost to the flat
horizontal shoulders 70 of the heat sink 46, but do not contact the
shoulders 70. The lower margins of the legs 82 lie between the lips
14 on the tray B and the upper regions 66 of the side walls 52 for
the heat sink 46. When the tray B is removed from the heat sink 46,
the legs 82 of the cover 80 drop downwardly and rest on the
shoulders 70 of the heat sink 46. But the ends of the cross wall 84
flare upwardly, leaving enough space between the shoulders 70 and
those flared ends to accommodate the handles 20 of a tray B. On the
other hand, where the cross wall 84 lies slightly above the upper
surface 18 on the lip 14, the legs 82 project downwardly to and
actually rest on the flat horizontal shoulders 70 of the heat sink
46 with the lip 14 on the tray B being between the regions of
contact. A clearance ranging up to 0.375 in. exists between the
bottom of the cross wall 84 and the upper surface 18 on the lip 14.
The legs 82 extend up to and nearly contact the overlying upper pan
38 of the cabinet 26. In the venting position the cover 80 is
reversed. Its legs 82 rest on the shoulder 70 of the heat sink 46
outwardly from the peripheral lip 14 of the tray B, but the cross
wall 84 lies well above the peripheral lip 14 and the handles 20.
This leaves an open space of at least 0.375 in. between the cross
wall 84 of the cover 80 and upper surface 18 on the lip 14 of the
tray B at each end wall 6 of the tray B, and moisture from the tray
B may escape through these spaces.
At the sides of the openings 36 in the front panel 28 and rear
panel 30, the cabinet 26 is fitted with pivotal stops 88 of the
triangular configuration. Each triangular stop 88 serves two
openings 36. It pivots at one of its apices, with the pivot axis
being slightly above, but otherwise between, the two openings 36
that the stop 88 serves. The other two apices project beyond the
upper regions 66 of the nearby side walls 52 for the heat sinks 46
at those openings 35. As such, those other apices project past the
ends of the openings 36, but not across, the opening 36.
The free apices of the stops 88 lie beyond the ends of the vertical
legs 82 for the covers 80 and retain the covers 80 in the upper
regions of the heat sinks 46. However, to reverse a cover 80 and
thereby change its position, the stop 88 at the heat sink 46 in
which the cover 80 fits, is pivoted away from the opening 36 at
that heat sink 46 so as to no longer block the opening 36. While
the stop 88 is held away from the opening 36, the cover 80 is
removed and reversed. Then the cover 80 is inserted back through
the opening 36 in the reversed position. Once the cover 80 is fully
within the heat sink 44, the stop 88 is released, and it assumes
its normal position, blocking the end of the opening 36 and thereby
retaining the cover 80 in the heat sink 46.
Finally, the cabinet 26 contains electrical controls 92 which
control the temperature at which the heating elements 78 of the
sinks 46 operate. A separate control 92 exists for each tier of
heat sinks 44. However, the controls 92 may be such that each heat
sink 46 is controlled individually.
The oven A normally awaits use in a restaurant with some of its
covers 80 in the sealing position and the remainder of its covers
80 in the venting position. As a meal time approaches, the
employees of the restaurant cook various foods for which the
restaurant expects to receive orders during the meal time.
Immediately after these foods are prepared, they are placed in the
trays B, each food being assigned to a different tray B. Some of
these foods, such as hamburger patties, loose their taste and
texture with loss of moisture. Others, such as fried chicken
fillets, biscuits, and eggs become soggy if stored in an abundance
of moisture. The trays B which contain foods that must remain moist
are placed in heat sinks 44 having their covers 80 in the closing
position (FIG. 3-left). The trays B containing foods which must
remain crisp are placed in heat sinks 44 in which the covers 80 are
in the venting position (FIG. 3-right). Each heat sink 44 directs
heat through the bottom wall 2 and side walls 4 of the tray B that
is within it, and the heat keeps the food in tray B warm--indeed,
warm enough to prevent bacterial contamination and warm enough to
serve to patrons of the restaurant when the demand arises, all with
the flavor and texture preserved.
To insert a tray B into a heat sink 44 having its cover 80 in the
closing position, the restaurant employee brings the tray B to the
rear panel 30 of the cabinet 26 and aligns it with one of the
openings 36 at a heat sink 46, the cover 80 for which is in its
closing position. The employee inserts the handle 20 of the tray B
beneath the upwardly flared end on the cross wall 84 for the cover
80 in that heat sink 46. Thereupon, the employee advances the tray
B into the heat sink 46, with the lip 14 of the tray B passing
beneath the cross wall 84 of the cover 80. When the tray B is fully
within the heat sink 46, the cross wall 84 of the cover 80
establishes a closure over the open top of the tray B and that wall
84 lies over the entire lip 14 along the periphery of the tray B.
Moisture remains trapped within the tray B, even though the heat
which is supplied by the heat sink 46 has the capacity to drive
moisture from the food. As a consequence, the food in the tray B
retains its taste and texture.
On the other hand, if the tray B contains a food which must remain
crisp, the employee selects a heat sink 46 which has its cover 80
in the venting position. The tray B when aligned with the opening
36 for this heat sink 46 passes easily into the cavity 48 of the
heat sink 46 with little manipulation, its lip 14 passing over the
shoulders 70 of the heat sink 46 and its bottom wall 2 over the top
surface 56 for the bottom wall 50 of the heat sink 46. The cross
wall 84 for the cover 80 remains well above the lip 14 on the tray
B, so that moisture from the food within the tray B may escape at
the open ends of the cover 80, that is to say over the end walls 6
of the tray B and beneath the cross wall 84 of the cover 80.
When the demand for a particular food arises within the restaurant,
other employees remove the tray B containing that food from the
oven A. This simply involves grasping the tray B by one of its
handles 20 and withdrawing it from its heat sink 46. In this
regard, the handles 20 project beyond the front and rear panels 28
and 30 of the cabinet 26 and are easily accessible.
Any cover 80 is easily withdrawn from its heat sink 46 by pivoting
the stop 88 at the one end of the heat sink 46 away from the
opening 36 at the end of that heat sink 46. This leaves the cavity
48 of the heat sink 46 unobstructed, and it is easily cleaned,
owing to its continuous and smooth surfaces. It also enables an
employee to easily clean the cover 80. And, of course, it permits
the employee to reverse the position of the cover 80.
The heat sink 46 efficiently transfers heat from its heating
element 76 to the tray B, thereby keeping the contents of the tray
B at a desired temperature with minimum expenditure of electrical
energy. The foods in the tray B that are withdrawn, even as long as
several hours after being inserted into the oven A, have
essentially the taste and texture that they possessed immediately
after being cooked. Since the trays B are totally isolated from
each other in .Iadd.separate compartments in .Iaddend.the cabinet
26, even when the covers 80 over those trays are in their venting
positions, flavors are not transferred between the foods in
different trays B. .Iadd.In one embodiment (FIGS. 3 and 4), each
compartment is defined by bottom wall 50, side walls 52, and top
wall 38 and is sized for receiving only one tray B per
compartment..Iaddend.
A modified cover 100 (FIG. 6) has side legs 82 and a cross wall 84
of essentially the same configuration as their counterparts in the
cover 80. However, the cross wall 84 contains openings 102 arranged
in a row between the legs 82. It also carries a slide 104 which
likewise contains openings 106. The slide 104 is captured on the
cross wall 84 such that it cannot be lifted from the cross wall 84,
yet it can slide longitudinally over the wall 84. Indeed, the slide
104 projects beyond the ends of the cross wall 84, so that it can
be manipulated from the exterior of the oven A to assume various
positions on the cross wall 84. In one position, the slide
completely covers the openings 102 in the wall 84, and in this
position the tray B is sealed. In other positions the slide 104
exposes the openings 102 in the wall 84 through its own openings
106, with the amount of exposure being dependent in the position of
the slide 104. In these positions the tray B is vented.
A modified tray C (FIG. 7) may be used in the heat sinks 46 to keep
foods warm, and it is similar to the tray B in all respects, except
the provision for removing it from and inserting it into the heat
sink 46. Whereas the tray B has handles 20 that are generally flat
and extend the full width of the tray B, the tray C has handles 108
that are narrow and resemble the handles on household frying or
sauce pans. The handles 108 project from the end walls 6 of the
tray C where they are located near the peripheral lip 14, but are
otherwise centered between the side walls 4.
Another modified cover 110 (FIGS. 7 & 8) works well with the
tray C, but is also suitable for use with the tray B. The cover 110
has legs 112 and a cross wall 114 extending horizontally between
the legs 112 to which it is attached. The legs 112 do not differ
from the legs 82 of the cover 80, and they rest on the horizontal
shoulders 70 of the heat sink 46, even when the tray C is in the
cavity 48 of the heat sink 46. Moreover, they extend up to and
nearly contact the pan 38 that overlies the heat sink 46 in the
cabinet 36. The cross wall 114 has an elevated region 116 where it
is joined to the legs 112 and a depressed region 118 located within
and being joined to the elevated region 116. The depressed region
118 has a peripheral wall 120 that is generally vertical and a
bottom wall 122 which lies below, yet parallel to, the surrounding
elevated region 116.
When the tray C is in the cavity 48 of the heat sink 46 (FIG. 8),
the bottom surface of the elevated region 116 in the cross wall 114
lies directly above the upper surface 18 on the tray B, there being
a gap of about 0.375 in. between the two surfaces. The peripheral
wall 120, on the other hand, is set inwardly from the upper surface
18 of the tray C and inwardly from the upper ends of the side walls
4 and end walls 6 as well, with the gap being about 0.375 in. The
lower surface of the bottom wall 122 lies in a horizontal plane
that is slightly above the plane defined by the upper surface 18 on
the tray C, with the spacing between the two planes being about
0.01 in. This spacing allows the tray C to be inserted into and
removed from the cavity 48 of the heat sink 46 without interference
from the cover 110.
At the ends of the cover 110 the elevated region 116 of the cross
wall 114 turns downwardly in the form of a vertical lip 124, the
lower edge of which lies in the plane of the lower surface on the
bottom wall 122. When the tray C is in the heat sink 46, the lips
124 lie slightly beyond the upper surfaces 18 at the ends of the
tray C, yet over or slightly beyond the depressed edges 16 at those
ends. The lips 124 and the nearby segments of the peripheral wall
120 for the depressed region 118 create labyrinths which retard
moisture from escaping from the tray C.
To enhance the seal established by the lips 124 and the depressed
region 118 of the cover 110, the lips 124 may be fitted with
elastomeric seal elements which bear against the end edges of the
laterally directed lip 14 of the tray C beyond the two end walls 6
of the tray C. Likewise, elastomeric lip seals may also be fitted
to the ends of the cross wall for the cover 80 to contact the lip
14 at the ends of the tray C and thereby enhance the sealing
capabilities of the cover 80.
The rear panel 30 of the cabinet 26, in lieu of having openings 36,
may be solid. In such an arrangement the rear panel 30 would block
one end of the cavity 48 for each heat sink 46, and the heat sink
46 itself could wrap around the end of the cavity to close it and
thus, transfer heat to that end wall 6 of the tray B which is
presented toward the closed end. The other end of the heat sink 46
would remain open and indeed would open out of the cabinet 36
through the aligned opening 36 in the front panel 28. Of course,
the handle 20 on that end of the tray B which faces the closed end
of the heat sink 46 would have to be removed or reconfigured, so
that it will not interfere with the solid rear panel 30.
Also, any tray B or C which must retain moisture may be fitted with
a separate cover, and that would eliminate the need for the covers
80 or 110. In this regard, covers are available on the market for
the traditional trays that resemble the trays B and C.
This invention is intended to cover all changes and modifications
of the example of the invention herein chosen for purposes of the
disclosure which do not constitute departures from the spirit and
scope of the invention.
Duke Manufacturing Company
TABLE-US-00001 Re: HOLDING OR COOKING OVEN A oven 50 bottom wall B
trays 52 side walls C tray 54 flat bottom surface 2 bottom wall 56
flat top surface 4 side walls 58 lower region 6 end walls 60 flat
outside surface 8 corners 52 contoured inside surface 10 offset
portion 64 curved corner 14 lip 66 upper region 16 depressed edge
68 offsets 18 upper surface 70 flat horizontal shoulders 20 handles
76 heating element 22 78 thermal insulation 24 80 cover 26 cabinet
82 legs 28 front panel 84 cross wall 30 rear panel 88 stops 32 end
panels 90 34 top panel 92 electrical controls 36 opening 100
modified cover 38 upper pan 102 openings 40 lower pans 104 slide 41
lips 106 openings 42 channels 108 handles 43 lips 110 modified
cover 44 rigidifying members 112 legs 46 heat sink 114 cross wall
48 cavity 116 elevated region 118 depressed region 120 peripheral
wall 122 bottom wall 124 vertical lip
* * * * *