U.S. patent application number 09/756941 was filed with the patent office on 2001-07-12 for holding or cooking oven.
Invention is credited to Luebke, Clement J., Shei, Steven M..
Application Number | 20010007322 09/756941 |
Document ID | / |
Family ID | 26961364 |
Filed Date | 2001-07-12 |
United States Patent
Application |
20010007322 |
Kind Code |
A1 |
Shei, Steven M. ; et
al. |
July 12, 2001 |
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.
Inventors: |
Shei, Steven M.; (Fort
Wayne, IN) ; Luebke, Clement J.; (St. Louis,
MO) |
Correspondence
Address: |
POLSTER, LIEDER, WOODRUFF & LUCCHESI
763 SOUTH NEW BALLAS ROAD
ST. LOUIS
MO
63141-8750
US
|
Family ID: |
26961364 |
Appl. No.: |
09/756941 |
Filed: |
January 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09756941 |
Jan 9, 2001 |
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09538761 |
Mar 30, 2000 |
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6175099 |
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09538761 |
Mar 30, 2000 |
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09282313 |
Mar 31, 1999 |
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Current U.S.
Class: |
219/399 ;
219/385 |
Current CPC
Class: |
A47J 39/006
20130101 |
Class at
Publication: |
219/399 ;
219/385 |
International
Class: |
F27D 011/00; F24C
007/04; F27B 005/02 |
Claims
What is claimed is:
1. In combination with plurality of trays, each having a bottom
wall and side and end walls attached to the bottom wall and
extending upwardly to an upper rim to provide an upwardly opening
interior for holding a food, an oven for transferring heat to the
interiors of the trays and the foods in such interiors, said oven
comprising: a cabinet; a plurality of tray-receiving members in the
cabinet, each tray-receiving member having a generally horizontal
cross wall and side walls connected to and extending generally
vertically from the horizontal cross wall to provide a generally
U-shaped cross section, each tray-receiving member being open at
its ends, the trays being in at least some of the tray-receiving
members such that the side walls of the trays are along the side
walls of the tray-receiving members in which they are located, the
side walls of the tray-receiving members serving to isolate the
interiors of the trays from each other so that the flavors of foods
in different trays do not transfer; and an electric heating element
positioned in the cabinet to direct heat into the trays in the
tray-receiving members.
2. The combination according to claims 1 wherein the side walls of
each tray-receiving member have horizontal edges located remote
from the horizontal cross wall; and wherein the oven further
comprises a horizontal closing wall located in the cabinet along
the horizontal edges of the side walls for at least one of the
tray-receiving members for closing the tray-receiving member and
preventing flavors from the foods in the tray that is in said one
tray-receiving member from transferring laterally past the
horizontal edges of the tray-receiving member.
3. The combination according to claim 2 wherein the horizontal
edges on the side walls of multiple tray-receiving members are
located along the horizontal closing wall.
4. The combination according to claim 3 wherein the horizontal
closing wall is continuous along the multiple tray-receiving
member.
5. The combination according to claim 2 wherein the heating element
is located along one of the horizontal walls.
6. The combination according to claim 2 wherein the oven further
comprises a heating element located along the horizontal cross wall
and side walls of each tray-receiving member.
7. The combination according to claim 2 wherein the side walls of
each tray-receiving member have upper and lower regions and
horizontal offsets between the upper and lower regions; and wherein
the tray that is within the tray-receiving member has its rim
located along the offset.
8. The combination according to claim 7 wherein the rim of each
tray includes a lip which projects laterally from the side walls
and lies along the horizontal offsets of the tray-receiving member
in which the tray is located.
9. In combination with a plurality of trays, each having a bottom
wall and side and end walls attached to the bottom wall and
extending upwardly to a laterally directed lip to provide an
upwardly opening interior for holding food, an oven for
transferring heat to the interiors of the trays and the foods in
such interiors, said oven comprising: a cabinet; first and second
members within the cabinet to define open-ended enclosures for
receiving the trays, each first member being generally U-shaped in
cross-section and including a horizontal cross wall and side walls
extending generally vertically from the horizontal cross wall, the
second member providing a cross wall that extends generally
horizontally between the side walls of at least one first member
and is spaced from the horizontal cross wall of the first member to
complete an enclosure in which one of the trays is located, whereby
the trays in different enclosures are isolated from each other and
flavors do not transfer laterally within the oven from the food in
one tray to the foods in other trays; and a heating element located
along one of the horizontal cross walls at each enclosure for
heating a tray in the enclosure.
10. The combination according to claim 9 wherein the side walls of
each first member have regions that are remote from the cross wall
for that first member and the cross wall provided by the second
member extends between the remote regions of the side walls for the
first member.
11. The combination according to claim 10 wherein heating element
at each enclosure also extends along the side walls for the first
member at that enclosure.
12. The combination according to claim 9 wherein the side walls of
each first member have upper and lower regions and horizontal
offsets between the upper and lower regions; and wherein the tray
that is within the enclosure formed in part by the first member has
its lips located along the offset.
13. The combination according to claim 9 wherein the second member
provides a cross wall for several first members.
14. The combination according to claim 9 wherein the heating
elements at each enclosure are controlled independently.
15. The combination comprising: a cabinet; a plurality of heat
sinks in the cabinet, each heat sink being formed from a good
conductor of heat and having a bottom wall and side walls that
extend upwardly from the bottom wall and together with the bottom
wall define a cavity having ends, at least one of which opens out
of the heat sink; a heating element on each heat sink for elevating
the temperature of the heat sink, each heating element being
controlled individually for controlling the temperature of its heat
sink; and at least one food container located in the cavity of one
of the heat sinks, the food container having a bottom wall that is
located along the bottom wall of the heat sink, side walls that
extend upwardly from the container bottom wall and are located
along the side walls of the heat sink, and end walls that extend
upwardly from the container bottom wall and connect the container
side walls, whereby heat from the heat sink is transferred to the
food container.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of application Ser. No.
09/538,761, filed Mar. 30, 2000, which is a continuation-in-part of
application Ser. No. 09/282,313 filed Mar. 31, 1999, now
abandoned.
BACKGROUND OF THE INVENTION
[0002] This invention relates in general to ovens and more
particularly to an oven for maintaining foods at temperatures
suitable for serving or for even cooking foods.
[0003] 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.
[0004] 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.
[0005] 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 overlying 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
[0006] 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.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0007] In the accompanying drawings which form part of the
specification and wherein like numerals and letters refer to like
parts wherever they occur:
[0008] 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;
[0009] FIG. 2 is a top and rear perspective view of the oven;
[0010] 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;
[0011] FIG. 4 is a fragmentary sectional view taken along line 4-4
of FIG. 3;
[0012] FIG. 5 is an exploded perspective view of a heat sink, the
cover for the heat sink, and a tray;
[0013] FIG. 6 is a perspective view of a modified cover.
[0014] FIG. 7 is an exploded perspective view of the heat sink, a
modified cover for the heat sink, and a modified tray; and
[0015] FIG. 8 is a fragmentary longitudinal sectional view of the
modified tray of FIG. 7 fitted beneath the modified cover of FIG.
7.
[0016] Corresponding reference numerals will be used throughout the
several figures of the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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 {fraction
(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 comers 8 of the tray B.
[0022] 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.
[0023] 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.
[0024] 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
surfaces 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.
[0025] 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.
[0026] 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.
[0027] 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 that
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.
[0028] 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.
[0029] 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 openings 36.
[0030] 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.
[0031] 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.
[0032] 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 the 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
1 Duke Manufacturing Company Re: HOLDING OR COOKING OVEN A oven B
trays C tray 50 bottom wall 2 bottom wall 52 side walls 4 side
walls 54 flat bottom surface 6 end walls 56 flat top surface 8
corners 58 lower region 10 offset portion 60 flat outside surface
62 contoured inside surface 14 lip 64 curved corner 16 depressed
edge 66 upper regions 18 upper surface 68 offsets 20 handles 70
flat horizontal shoulders 22 24 26 cabinet 76 heating element 28
front panel 78 thermal insulation 30 rear panel 80 cover 32 end
panels 82 legs 34 top panel 84 cross wall 36 opening 38 upper pan
88 stops 40 lower pans 90 41 lips 92 electrical controls 42
channels 43 lips 44 rigidifying members 46 heat sink 100 modified
cover 48 cavity 102 openings 104 slide 106 openings 108 handles 110
modified cover 112 legs 114 cross wall 116 elevated region 118
depressed region 120 peripheral wall 122 bottom wall 124 vertical
lip
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