U.S. patent number RE30,623 [Application Number 06/145,953] was granted by the patent office on 1981-05-26 for apparatus for selectively heating an individual food item in a refrigerated environment.
This patent grant is currently assigned to UOP Inc.. Invention is credited to Gerard T. Hogan, Ralph R. Pecoraro, William J. Schulz.
United States Patent |
RE30,623 |
Schulz , et al. |
May 26, 1981 |
Apparatus for selectively heating an individual food item in a
refrigerated environment
Abstract
A cabinet type enclosure, preferably in the form of a cart,
which is adapted to be connected to a source of refrigeration for
refrigerating a plurality of food items on a plurality of meal
trays positioned in the enclosure has a plurality of thin,
generally horizontal fixedly mounted heater shelf members extending
into the enclosed space from one side wall thereof. The heater
shelf members are adapted to be moved relative to and under hot
food containers positioned on the trays to heat same. The enclosure
also has pairs of tray guides on its opposing side walls. The meal
trays have integral transverse abutment means which extend over a
portion of the tray surface at a location above the surface. The
transverse abutments cooperate with a container for hot food placed
on the tray between the abutment means for preventing movement of
the hot food container past the transverse abutment means by
frictional contact with the heater shelf as the tray is moved into
or out of the enclosure and relative to the heater shelf along the
tray guides. The heater shelf members are positioned so that they
will pass between the tray surface and the bottom of the abutment
means. A ramp-like end on the heater shelf will engage and lift the
chamfered bottom of a container to be heated so that the container
will be gently lifted upwardly onto the heater shelf as the tray is
moved to a position overlying a heating element on the heater
shelf. The apparatus is particularly useful for inflight feeding as
well as for institutional feeding.
Inventors: |
Schulz; William J. (West
Cornwall, CT), Pecoraro; Ralph R. (Jacksonville, FL),
Hogan; Gerard T. (Roscoe, IL) |
Assignee: |
UOP Inc. (Des Plaines,
IL)
|
Family
ID: |
26843431 |
Appl.
No.: |
06/145,953 |
Filed: |
May 2, 1980 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
889763 |
Mar 24, 1978 |
04180125 |
Dec 25, 1979 |
|
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Current U.S.
Class: |
165/48.1; 165/64;
165/919; 219/386; 219/400; 312/236 |
Current CPC
Class: |
F25D
23/12 (20130101); F25D 19/003 (20130101); A47J
39/006 (20130101); A47B 2031/002 (20130101); A47B
2031/026 (20130101); B62B 2202/67 (20130101) |
Current International
Class: |
A47J
39/00 (20060101); F25D 19/00 (20060101); F25D
23/12 (20060101); F25B 029/00 () |
Field of
Search: |
;165/DIG.25,DIG.26,48,64
;312/236 ;219/386,387,400,432,433,438 ;126/246,268 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Davis; Albert W.
Assistant Examiner: Focarino; Margaret A.
Attorney, Agent or Firm: Hoatson, Jr.; James R. Clark; Barry
L. Page, II; William H.
Claims
We claim as our invention:
1. An apparatus for heating at least one covered container on a
meal service tray while other items on the tray are refrigerated
comprising an enclosed housing having a plurality of cooperative
pairs of guide rails therein for supporting a first pair of opposed
side edges of a plurality of trays; means for supplying a
refrigerated atmosphere within said enclosure; a plurality of
generally horizontal, thin, heater shelves extending from a side
wall of said housing for less than one-half the width of the trays;
a ramp surface on at least one end of each of said heater shelves;
a plurality of trays, each of said trays having at least one pair
of abutment portions integrally supported by said trays and
extending transversely over a portion thereof relative to said
first opposed pair of side edges, said abutment portions being
located sufficiently far above the serving surface of the trays to
permit end contact with said at least one covered container while
allowing the trays to be slid along said cooperating pairs of guide
rails so that said thin heater shelves will pass above the tray
surfaces and .[.beneath the.]. .Iadd.under said container contacted
by said .Iaddend.abutment portions, the ramp surface on each of
said heater shelves being adapted to lift a covered container
located on said tray between said at least one pair of abutments,
.[.and.]. .Iadd.whereby to .Iaddend.permit said heater shelf with
which said container is frictionally engaged to pass under it as
said container is restrained by one of said at least one pair of
abutment portions.
2. The apparatus of claim 1 wherein said cooperative pairs of guide
rails are located in said housing at a vertical offset relative to
each other so that a tray resting on them will be at a slight angle
to horizontal.
3. The apparatus of claim 2 wherein said heater shelves are located
on the side wall of the housing which supports the lowermost of
said pairs of guide rails, said heater shelves projecting
downwardly toward the center of the housing at a slight angle to
the horizontal.
4. The apparatus of claim 3 wherein the angle assumed by a tray on
said guide rails and the angle of said heater shelves are each
about 21/2.degree. so that a container resting on a heater shelf
will be tilted at an angle of about 5.degree. relative to the
bottom of its tray.
5. The apparatus of claim 4 wherein said trays include a
longitudinal abutment portion positioned intermediate spaced
portions thereof which accommodate hot food and cold food, said
last named container being biased by the effect of gravity and its
angle of tilt relative to said tray into engagement with said
longitudinal abutment portion.
6. The apparatus of claim 1 wherein said heater shelves are
principally of laminated resin and glass construction with heater
elements embedded therein at spaced locations.
7. The apparatus of claim 6 wherein said ramp surfaces are formed
of a non-laminated material having a retaining portion positioned
internally of said laminated construction.
8. The apparatus of claim 1 wherein said trays and at least one of
each of said pairs of guide rails include complementary detent
means to positively locate each of said trays within said enclosed
housing at a predetermined distance from a door mounted
thereon.
9. The apparatus of claim 1 wherein said means for supplying a
refrigerated atmosphere comprises a pair of selectively closable
openings in a door portion of said apparatus, said openings being
adapted to be connected to a pair of inlet and outlet ducts
attached to an air chilling unit.
10. The apparatus of claim 9 wherein said enclosed housing has a
baffle member mounted in one end thereof for preventing the flow of
chilled air directly from the inlet opening to the outlet opening
without passing back and forth over the trays mounted in the
housing.
11. The apparatus of claim 1 wherein said covered container has
generally vertical side edges which are chamfered at the bottom to
coact with said ramp surface to facilitate the lifting of said
container by said ramp surface.
Description
BACKGROUND OF THE INVENTION
The invention relates to the heating and cooling of food items on
meal trays in inflight, institutional or similar types of mass
feeding operations. In all of such operations it is desirable that
the food reach the person for whom it is intended in a tasteful
condition with the hot items hot and the cold items cold. A minimum
of handling of the trays is also desirable to reduce the labor cost
of serving and a minimum of weight is desirable to ease handling
and reduce cost. The weight aspect is especially important for
inflight feeding systems. Numerous patentees have attempted to
resolve the problem but none completely successfully. Patents
related to this subject matter include U.S. Pat. Nos.: Reynolds
2,616,269, Hilliker 2,919,339, Bauman 3,042,384, Traycoff
3,129,041, Foster et al 3,199,579, Stenz 3,205,033, Stenz et al
3,275,393, Nicolaus et al 3,389,946, Golden 3,408,481, Shevlin
3,608,627, 3,725,645, 3,784,787 and 3,830,148, Stevenson 3,615,713,
Williams 3,908,479, Mack et al 3,924,100, Colato et al 4,005,745,
Shumrack et al 4,041,277, Wyatt 4,052,589 and Tricault French Pat.
No. 1,219,352. Some of these systems provide separate hot and cold
compartments for hot and cold items and require the assembly of the
hot items to the tray of cold items before serving. This is
wasteful of labor and, in the case of hospitals, can make it
possible for a patient on a restricted diet to receive the wrong
food items. Other of these patents require heavy, bulky hot food
containers which include integral heaters. There are also systems
where each food tray must have its own heater elements. Reynolds
teaches heating liquid or solid food in a container in a
refrigerated atmosphere but the food is not on a tray. Others, such
as Colato et al U.S. Pat. No. 4,005,745 and the Tricault French
Pat. No. 1,219,352 also heat in a refrigerated atmosphere with the
food items being on trays and with the hot food container being
normally positioned in a hole in the tray which supports its side
edges during carrying. The hole permits the hot food container to
be positioned directly over a heating element which is located so
as to lift the hot container from the tray as it is being heated.
This type of system assures excellent direct contact between the
heater and container but presents a danger that a person could be
burned or could spill the tray if he accidently put his fingers
under the hot dish. The danger would be minimal in a hospital where
the tray server places the meal on the bed table but would be much
more significant in an aircraft where the passengers often assist
in the passing of trays to the window seat. Furthermore, the
grabbing of the tray by the passenger on its close edge with his
fingers under the entree portion of what he assumes is a solid tray
would possibly cause his fingers to propel the entree into his lap
or his neighbor's while the rear edge of the tray falls for lack of
support, thereby dumping the cold items on someone's legs or the
floor. The aforementioned spillage problem could be avoided by
using a second tray under the apertured one during serving but this
would take assembly time on the part of the server and introduce
additional weight to the aircraft.
SUMMARY
It is among the objects of the present invention to provide an
apparatus for storing, refrigerating and heating meals, especially
aboard aircraft, in such a manner that the food, both hot and cold,
will reach the consumer thereof in an optimum temperature
condition, while requiring no expenditure of time on the part of
the server to assemble the items which constitute the meal.
It is another object of this invention to provide such an apparatus
that is light in weight and easy to sterilize.
These and other objects are achieved by the system or apparatus of
the present invention wherein portions of the tray carrying
enclosure or cabinet, which is preferably in the form of a cart,
cooperate with portions of the trays and at least the hot food
containing dishes thereon to heat such dishes by applying heat
directly to their bottoms while the dishes are temporarily
positioned above the solid bottom surface of the tray. The cabinet
or enclosure contains a plurality of vertically spaced side guide
rails for supporting a plurality of meal service trays in a
normally refrigerated atmosphere. To maximize their storage
capacity the cabinets preferably are deep enough to accommodate two
trays end to end in their longest dimension on each set of guide
rails. A generally horizontal thin heater shelf is located in the
cabinet in association with each set of side guide rails. The
heater shelves are preferably wired so that at least some shelves
can be left unheated when the cabinet is not fully loaded. The
shelves extend from one side wall of the cabinet such that the top
surfaces of the entree or passenger facing halves of the trays can
be slid under the heater shelves as the trays are loaded into the
cabinet. Each heater shelf has heater elements positioned along its
length at locations which correspond to the final location in the
cabinet of the entree or other dishes to be heated. The heater
shelves are preferably of resin and glass mat laminated
construction and the heater elements, which can be of various
constructions such as etched metal, resistive wire, resistive
powder metal, carbon semiconductors or a pyropolymer such as
disclosed in Tadewald U.S. Pat. No. 3,973,103, are preferably
embedded in the laminate. There can be one heater element per tray
or more than one if it is desired to have the tray contain more
than one hot dish. Suitable detent means such as a dimple in the
tray bottom and a cooperating bump on the guide rail can be used to
properly register the trays and heaters, thus assuring proper
heating and cooling. The heater shelves are tapered at at least one
end thereof and preferably both where the cabinet can be loaded or
unloaded from each end. The taper can be formed in any suitable
manner such as by machining an untapered laminate member or by
embedding a metal or plastic member of appropriate tapered shape in
a laminate as it is being formed. The taper provides a ramp surface
which the hot dishes ride up on in order to reach the top surface
of the heater shelf. The hot dishes must maintain a relatively
fixed longitudinal position relative to the tray surface as the
tray is slid along the guide rails. This relationship is maintained
by virtue of a pair of transverse abutment portions which are
integral with the tray. The abutment portions intercept the
preferably vertical upper edge portions of the ends of the hot dish
and keep the dish from traveling with the heater shelf which is
moving under it in a relative sense when the tray enters or leaves
the cabinet. The heater shelves should be wide enough to be
completely under the hot dishes and the abutment means must project
sufficiently far to intercept the hot dishes and maintain their
orientation. The active or container contacting portions of the
abutment means must be vertically spaced from the tray surface a
sufficient distance to avoid interference with the heater shelf. A
longitudinally extending abutment is also preferably provided which
can contact the rear side of the hot dish. It is desirable to force
the hot dish against the longitudinally extending abutment to
better retain the hot dish in position on the tray as the tray
passes under the heater shelf. Although the tray and guide rails
can be horizontal, retention can be slightly assisted by mounting
the guide rails so that the tray will be slightly tilted downwardly
(about 21/2.degree.), and thus assisted by gravity during insertion
to move toward the heater shelf side of the cabinet and engagement
with the cart wall or the detent means. It is quite desirable to
mount the heater shelves so as to tilt downwardly (about
21/2.degree.) toward the center of the cabinet. Gravity can then
help force the dishes on the shelves against the longitudinally
extending abutment. The angle of the heater shelves also assists in
the draining of water from the shelves when the cabinet is
washed.
The cart interior is normally maintained at a temperature cooler
than ambient and can be cooled in any suitable manner such as by
being moved into contact with supply and return ducts of a
refrigeration unit built into the galley of an aircraft, for
example. The air can pass through a first port in the cart,
circulate over the trays, and exit through a second port.
Alternatively, the galley unit could be formed to sealingly engage
with an end of a cart whose door is opened. Other cooling means
could be used such as a nozzle which injects liquid nitrogen into
the cart. Dry ice or regular ice could also be used as an external
source of cooling air or could be placed in a cart.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a meal tray being loaded into
a combination meal tray storage and serving cart;
FIG. 2 is a fragmentary front view of a portion of the cart shown
in FIG. 1 illustrating the heater shelves and the relationship
between a heater shelf and a hot food containing container before
and after engagement of the container with the heater shelf;
FIG. 3 is a perspective view of a tray in accordance with the
invention with a portion of one corner removed to illustrate a
detent means for retaining the tray in a fixed position relative to
one of the guide rails in the serving cart;
FIG. 4 is a view taken on line 4--4 of FIG. 1 illustrating the ramp
portion of the heater shelf;
FIG. 5 is a somewhat schematic representation of the relationship
between the cart of FIG. 1 and a food chilling unit which is
integrally housed inside an aircraft;
FIG. 6 is a view taken on line 6--6 of FIG. 5 showing an iris type
air inlet port in the cart; and
FIG. 7 is a view showing the iris mechanism of FIG. 6 in the closed
position which it would assume when the cart is disconnected from
the chilling unit.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1 a meal tray storage and service cart is
indicated generally at 10. The cart has side walls 12, 14, a top
wall 16 and a bottom wall 18 which, together with pivoted doors 20,
22 mounted to the cart by hinges 24, define an enclosure which is
preferably sealed by a flexible sealing strip 26. All of the walls
are preferably insulated. The cart 10, as shown, is particularly
well adapted for use in an aircraft wherein wheels 28 permit the
unit to be rolled from its storage position in the galley as
indicated in FIG. 5 to its serving position wherein it is rolled up
and down the aircraft aisle by the flight attendants. By providing
doors 20, 22 at each end of the cart, it is possible to have
attendants simultaneously serving meals from each end of the
cart.
Positioned on the inside of wall 12 are a plurality of guide rail
members 30 which may be attached to the wall by screws, spot
welding or other fastening means. Extending from the inner wall of
the opposite side 14 of the cart are somewhat similar guide rails
32 which are preferably positioned at a slightly lower level than
the corresponding rails 30 on the opposing side 12. Tray retaining
projections 34 are formed in any suitable manner at two locations
on the rails 32 and serve to define the positioning of the two
trays 54 carried by each set of guide rails within the cart.
Positioned slightly above the lowermost guide rails 32 are fixed
heater shelves indicated generally at 40 which may be screwed or
otherwise fastened to the side walls 14. The heater shelves 40
include a tapered ramp portion 44 on at least one end and
preferably both ends where the cart is to be loaded or unloaded
from either end as well as an elongated longitudinal portion 46,
preferably of a resin and glass laminate, in which are mounted
electrical heating elements 48. The number of heating elements 48
is determined by the number of hot dishes to be heated. In the
present embodiment, we have shown two hot dishes on each tray 54
with there being two trays on each set of guide rails 30, 32.
However, a single heater for each tray would also be suitable if
only one entree dish needs heating. The tray 54 can be seen in more
detail in FIG. 3 wherein it can be seen that the tray includes a
large flat surface 56 at its rear for cold foods, a coffee cup and
silverware for example. An edge portion 58 surrounds the outside of
the cold surface and contributes to the rigidity of the tray in
addition to its function of retaining items from sliding off the
tray. A second portion 60 of the tray 54 comprises an extended flat
surface area 60 for receipt of hot foods with the foods being
prevented from sliding off the tray by a raised front edge portion
62. A recessed detent portion 64 is preferably provided in one
corner of the tray and is designed to cooperate with complementary
retaining projections 34 formed on the rails 32 in order to
positively locate the trays 54 inside the unit 10 as shown in FIG.
5 so that air will be free to circulate around the ends of the
trays. A raised central rib portion 66 separates the cold portion
56 from the hot portion 60 of the tray and may provide some degree
of insulation between the hot and cold portions as well as
providing support for the transverse abutment portions 68, 70, 72
whose function will presently be described. The raised portion 66
also may define longitudinal abutment portions 74, 76 which limit
rearward movement of containers 80, 82.
As seen in FIG. 1, a hot entree dish 80 and a secondary hot dish
82, which may be omitted, are covered with heat and moisture
retaining covers 84, 86 respectively. The entree dish 80 is
preferably made of a ceramic or plastic material which will permit
the entree to remain in a hot condition until served, even though
the cart 10 is disconnected from its source of power during the
serving operation. A coffee cup 90 and a dish 92 for a salad,
dessert or other cold item is provided on the unheated portion 56
of the tray. As seen in FIG. 2, the side edges 94 of the entree
dish 80 are generally vertical while the bottom of the dish is
generally chamfered as shown at 96. When a tray 54 is loaded into
the cart 10 as shown in FIG. 1, the chamfered dish bottom 96
engages and cooperates with the ramp edges 44 of the heater shelf
40 to generally cam up or lift the leading edge of the dish 80
upwardly until the dish overlies the heater shelf. The vertical
dish edges 94 engage the transverse abutments 70 or 68 on the tray
54 depending upon whether the tray is being inserted into the cart
10 or removed therefrom. During insertion, the frictional
engagement between the fixed heater shelf 40 and the dish 80 on the
moving tray 54 will naturally tend to force the dish rearwardly
against the abutment 70 while the friction force would of course be
in the opposite direction during the removal of the tray from the
cart. As previously mentioned, the guide rails 30, 32 are slightly
vertically offset from each other. In FIG. 2 the angle of offset
.alpha. as defined by the arrows is preferably about 21/2.degree..
The heater shelves 40 are preferably mounted at a similar angle
.beta. in the opposite direction so that as a tray and entree dish
are loaded into the cart the dish 80 will be lifted and rotated as
it encounters shelf ramp 44 from the upper position shown in FIG. 2
to the storage and heating position shown at the bottom of FIG. 2.
In the storage and heating position, the respective 21/2.degree.
angles of the tray and heater shelf cause a resultant 5.degree.
angle between the dish 80 and the bottom of the tray 54. This
configuration minimizes spilling of any liquids within the
container 80 while utilizing the effect of gravity to urge the
container 80 into contact with the longitudinal abutment 74 as the
tray 54 and container 80 are slid longitudinally over the surface
46 of the heater shelf 40. The angled relationship in cooperation
with the complementary detent means 34, 64 insures that the hot
dishes 80, 82 will be positioned exactly as desired relative to the
heater plates 48. Little or no heat will be wasted since the heat
will transfer directly to the overlying dishes 80, 82. The firm
contact of the dishes 80, 82 with the longitudinal abutments 74, 76
also permits the transverse abutments 68, 70, 72 to be relatively
short while still being effective, thus minimizing the possibility
of these members being broken off during tray washing and handling
operations.
FIG. 5 illustrates one manner in which the cart 10 may be mounted
in a galley of an aircraft. The aircraft fuselage 100 is
illustrated as containing a refrigeration unit 102 having inlet and
outlet ducts 104, 106 to the cart 10 which are connected by bellows
members 108 to normally covered openings in the door 22. The
closures for the openings could be of any desired construction
which would permit the cart to be sealed as it is being transported
from the food preparation kitchen to the aircraft. For example, a
flexible flap could be used or, as indicated in FIGS. 6 and 7, an
iris assembly having movable blades 112 could be utilized. A baffle
member 116 is preferably mounted between the walls 12, 14 of the
cart to block direct passage of air between the inlet duct and
outlet duct and insure that flow will be over the tray surfaces as
indicated by the arrows. The heater elements 48 are wired through
suitable switches (not shown) to a power cord 118 connected to the
aircraft electrical supply. If desired, sufficient switches may be
provided so that when the cart 10 is not filled with trays, the
unused heater elements 48 may be switched off. A timer mechanism
(not shown) may also be provided so that on a long flight, for
example, the trays, including the items to be served hot, can be
kept chilled. The heaters would then be activated at a sufficient
time in advance of the meal serving time to heat the dishes to
their serving temperature.
* * * * *