Note: Descriptions are shown in the official language in which they were submitted.
CA 02322319 2000-10-25
MICROWAVE VENDING MACHINE
This is a divisional application of parent
Application Serial No. 2,032,588 fiv ed in Canada on
December 18, 1990.
Technical Field
The disclosed invention relates to a hot meal
vending device which employs a combination of micro-
wave and convection heating.
Background of Invention
Vending machines for dispensing hot and cold
drinks, candy, cookies, potato chips and other snack
foods have enjoyed significant commercial success.
However, vending machines for dispensing meals have
been limited to dispensers of refrigerated foods such
as sandwiches, salads and the like.
Devices heretofore ddvi-sed for incorporating
electronic ovens in food vending machines are dis-
closed in U.S. Patent No. 3,333,666; U.S. Patent No.
3,343,479; U.S. Patent No. 3,386,550; U.S. Patent No.
3,397,817; U.S. Patent No. 3,534,676; U.S. Patent No.
4,004,712; U.S. Patent No. 4,398,651; U.S. Patent No.
4,592,485; U.S. Patent No. 4,762,250; U.S. Patent No.
4,783,582 and U.S. Patent No. 4,784,292.
Vending machines for hot meals generally include
a refrigerated compartment for preserving food, a
microwave oven compartment for fast cooking, and a
conveyor for transferring food from the refrigerated
compartment into the microwave oven. However, since
vending machines for hot foods have enjoyed very lim-
ited commercial success, separate microwave ovens for
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2
heating food items removed from a refrigerator are
commonly employed in convenience stores, airports,
cafeterias and other food vending operations.
Microwave heating of certain foods, including
pizza and sandwiches which contain dough and bakery
products, typically leaves the surface too moist and
less palatable than similar food products cooked in
other types of ovens.
Ovens of the type disclosed in U.S. Patent No.
3;884,213; U.S. Patent No. 4,154,861; U.S. Patent No.
4,289,792; U.S. Patent No. 4,409,453 and U.S. Patent
No. 4,835,351 employ air jets which impinge upon the
surface of a food product to provide surface heating
of the product in combination with microwave heating.
Jet impingement ovens have enjoyed significant success
in commercial food service and commercial food pro-
cessing operations. However, a long felt need exists
for apparatus for quickly and efficiently heating food
products which require little or no preparation for
use in a vending machine for hot meals.
Summary of Invention
The vending machine for hot foods includes an
oven cabinet having an interior divided by a perfo-
rated plate to prevent transfer of microwave energy
from a cooking compartment to an air conditioning
compartment in the cabinet. The conditioning chamber
houses air circulating apparatus to recirculate tem-
perature controlled air from the conditioning chamber
through the cooking chamber to facilitate crisping and
browning to provide a desired surface texture. Micro-
wave heating apparatus communicates with the cooking
chamber to provide rapid heating of the food by elect-
romagnetic excitation.
A method for controlling the temperature and
surface texture of a product includes the steps of:
CA 02322319 2000-10-25
3
positioning a product in a container having upwardly
extending sides and a bottom; positioning the product
and container in a temperature controlled atmosphere;
supporting the product above the bottom of the container;
and forming a region of controlled air pressure
alternately adjacent opposite sides of the product by
directing air to flow alternately adjacent opposite sides
of the product such that temperature controlled air flows
between the lower surface of the product and the bottom
of the container.
An aspect of the present invention provides a method
of controlling the temperature and surface texture of a
product comprising the steps of: positioning a product
in a container having upwardly extending sides and a
bottom; positioning the product and container in a
temperature.controller atmosphere; and forming a region
of controlled air pressure alternately adjacent opposite
sides of the product such that temperature controller
air flows between the lower surface of the product and
the bottom of the container.
Another aspect of the present invention provides a
microwave oven comprising: a cabinet; means dividing
the interior of the cabinet into a cooking chamber and a
conditioning chamber, said conditioning chamber having a
volume greater than the volume of the cooking chamber;
circulating means in said conditioning chamber to
recirculate air from the conditioning chamber through
said cooking chamber; and microwave heating means
communicating with said cooking chamber, said means
dividing the interior of the cabinet being adapted to
prevent transfer of
CA 02322319 2000-10-25
3a
microwave energy from said cooking compartment to said
conditioning compartment.
Yet another aspect of the present invention provides
an oven comprising: a cabinet forming a cooking chamber;
a container having a bottom and side walls; support
means on said bottom wall adapted to support a food
product spaced from said bottom wall; air circulating
means adapted to direct a stream of air toward a product
in said container, said stream of air having a cross
sectional area which is less than the area of the surface
of a product ins aid container; and means to direct said
air stream to move air between the lower surface of the
food product and the bottom of the container.
Yet another aspect of the present invention provides
i5 an oven comprising a blower housing having intake and
outlet openings; blower means in said blower housing
adapted to circulate air from said inlet opening to said
outlet opening; air return means communicating with said
inlet opening; collector means in said air return means;
and means maintaining said collector means at a
temperature less than the temperature of circulating air
to collect airborne particles adjacent said collector
means.
Yet another aspect of the present invention provides
a method of serving food in an open-top container
comprising: the steps of: enclosing the food and
container in a telescoping sleeve; removing the
container from the sleeve; heating the food in the
container; returning the heated food and container into
the sleeve; and dispensing the sleeve, container and
food.
CA 02322319 2000-10-25
3b
Yet another aspect of the present invention provides
a heated food vending apparatus means comprising: a
container; a food product in said container; a cover on
said container; means to uncover said food product in
said container; means to heat the food by application of
streams of air projected toward the food product from the
uncovered top side; and means to cover the heated food
and container after heating.
- Yet another aspect of the present invention provides
a vending apparatus comprising: a product in an open top
container; sleeve cover around said container; a
heating chamber; means to push said container out of said
sleeve cover into said heating chamber to heat the food
product; and means to return the heated product and the
container to said sleeve cover.
Yet another aspect of the present invention provides
an apparatus to dispense a heated food product
comprising: an oven having a heating chamber; first
plunger means to push the product to be heated into said
heating chamber, and a second plunger means which
initially passes laterally over the product and then
vertically to contact the back of the product and pull
the product out of the heating chamber.
In a further aspect, the present invention provides
a heated food vending apparatus means comprising: a
container; a food product in said container; a cover on
said container; means to remove said cover of said
container; means to heat the food by application of
streams of air projected toward the food product; and
means to cover the food and container after heating.
In a still further aspect, the present invention
provides an apparatus to dispense a heated food product
CA 02322319 2003-11-21
3c
in a closed container comprising: an oven having a heating
chamber; first plunger means to open the container and move
the food product to be heated in the open container into said
heating chamber; and second plunger means adapted to move the
open container and the product out of the heating chamber and
to close the container after removing the container from the
heating chamber.
In a further aspect, the present invention provides a
vending apparatus for a heated product comprising: a heating
chamber; a product in an open top container; sleeve cover
around said container; means to push said container out of
said sleeve cover into said heating chamber to heat the
product; and means to return the container from said heating
chamber to said sleeve cover.
Description of Drawings
Drawings of a preferred embodiment of the microwave
vending machine are annexed hereto so that the invention may
be better and more fully understood, in which:
FIG. 1 is a perspective view of a package handling
apparatus and oven cabinet inside a vending machine, the
outer cabinet of the vending machine being broken away to
more clearly illustrate details of construction;
FIG. 2 is a cross-sectional view taken along line 2-2 of
FIG. l;
FIG 3 is a cross-sectional view taken along line 3-3 of
FIG. 2;
FIG. 4 is an exploded perspective view of the air
dispensing apparatus;
FIG. 5 is a cross-sectional view taken along line 5-5 of
FIG 1;
CA 02322319 2000-10-25
3d
FIG. 6 is a cross-sectional view taken along line 6-
6 of FIG.1;
FIG. 7 is an exploded perspective view of a
container and protective sleeve which form a package for
a food product;
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P-15,094
4
FIG. 8 is an elevational view of the package
illustrated in FIG. 7, parts being broken away to more
clearly illustrated details of construction;
FIG. 9 is a fragmentary diagrammatic view il-
lustrating a modified form of a food container having
susceptor film mounted therein;
FIG. 10 is a fragmentary diagrammatic view of a
food container having a bottom layer of french fried
food material and an upper layer of a different food
product;
FIG. 11 is a diagrammatic view illustrating air
flow during a first stage of the cooking process; and
FIG. 12 is a diagrammatic view similar to FIG. 11
illustrating air flow during a second stage of the
cooking process;
FIG. 13 is a perspective view of the external
vending machine cabinet;
FIG. 14 is a cross sectional view taken through
the electromechanical linear actuator;
FIG. 15 is a diagrammatic view similar to FIG. 11
illustrating air flow through a particulate food prod-
uct;
FIG. 16 is a perspective view of a container
having a lattice bridging the open top thereof;
FIG. 17 is a perspective view of the bottom of
the container illustrated in FIG. 16;
FIG. 18 is a cross-sectional view taken along
line 18-18 of FIG. 16; and
FIGS. 19-21 are cross-sectional views similar to
FIG. 18 diagrammatically illustrating the progressive
heating of a film sealing the container to uncover a
food product in the container.
Numeral references are employed to designate like
parts throughout the various figures of the drawing.
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P-15,094
- 5
Description of Preferred Embodiment
Referring to FIGS. 1, 4, 7 and 13 of the draw
ings, the numeral 10 generally designates a package
which is moved by package handling apparatus 40 into
and out of an oven 70 in a vending machine 200. As
will be hereinafter more fully explained, a source 90
of electromagnetic radiation and air circulating appa-
ratus 100 are employed for heating a food product 30
selected by a consumer upon depositing the purchase
price of the food product in the vending machine 200
illustrated in FIG. 13. As best illustrated in FIG.
13 of the drawing, the vending machine 200 is prefera-
bly adapted to serve, far example, hot food products
30 to a customer within about one and a half to two
minutes. In the illustrated embodiments, the food
products 30 may, for example, include french fried
potatoes, chicken nuggets, pizza, and submarine sand-
wiches.
The vending machine 200 is mounted in an enclo-
sure cabinet having a back wall 201, spaced side walls
202 and 204, a front panel 205, a top wall 206_and a
bottom wall 208. The front panel 205 is preferably
hingedly secured to side wall 202 and provided with a
key actuated lack 210 securing the front panel 205 in
a closed and locked position to prevent unauthorized
access to the interior of the enclosure. A currency
receiving mechanism 212 adapted to accept both coins
and bills is mounted on front panel 205 along with a
coin return slot 214 for returning change to the cus-
tourer.
Selector plates 216, 218, 220 and 222 are mount-
ed on the front panel 205 for use by the customer to
designate the food item selected to be heated and
dispensed through a delivery passage 224 closed by a
protective door 225. Product identification panels
CA 02322319 2000-10-25
. P-15,094
6
215, 217, 219 and 221 are associated with selector
plates 216, 218, 220 and 222, respectively, to inform
the customer what food item can be selected by touch-
ing one of the selector plates. Identification panel
215 is provided with a graphic illustration of fried
potatoes permitting use of the vending machine 200 by
persons who do not speak or read a particular lan-
guage. Additional indicia including words, numerals
or other and graphic representations may be applied to
each of the panels 215, 217, 219 and 221.
A condiment holding chamber 209 is provided for
holding packets of salt, pepper, sugar, ketchup, mus-
tard and barbecue sauce.
As will be hereinafter more fully explained, a
refrigerated food storage cabinet 170 is preferably
mounted in the lower portion of the interior of the
enclosure 200 and package handling apparatus 40 and
oven 70 are mounted above and adapted to receive se-
lected packages of food products from the refrigerated
storage compartment 170 transported by an elevator
180.
Each selector plate 216, 218, 220 and 227 is
preferably connected to an electrical circuit adapted
to initiate a sequence of events provided that payment
for the food item 30 has been received in the currency
receiving mechanism 212. As will be hereinafter more
fully explained, touching selector plate 220 indicates
that pizza, graphically illustrated on product identi-
fication panel 219 is to be dispensed. A container 10
containing pizza will be automatically moved from the
refrigerated storage compartment 170 onto an elevator
180 and delivered to the package handling apparatus 40
which will move the package 10 to oven 70 for heating
and then dispense the heated product 30 through the
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P-15,094
7
delivery passage 224 which is accessible to the cus-
tomer by raising door 225.
The electrical circuit controlling the heating of
the selected food product 30 preferably includes three
programmed elements for delivering a predetermined
type of heating for a pre-programmed time interval to
the selected food product. The programmable circuit
preferably includes, for example, devices to program
the heating cycle by coordination with the location of
the selected food item in the storage compartment 170,
a bar code or other readable mechanism on the package,
and symbols displayed on or adjacent selector plates
215-221 for the user to touch. From the foregoing, it
should be readily apparent that touching one of the
selector plates 216, 218, 220 or 222 based on the
visual selection of a food item graphically
illustrated on product identification panels 215, 217,
219 or 221 initiates a programmed sequence to control
the heating cycle of the selected food product 30.
Package 10, best illustrated in FIGS. 7 and 8,
comprises a tubular sleeve 12 having open ends 13a and
13b. Sleeve 12 is formed by a top 14, bottom 15 and
side walls 16a and 16b having peripheral edges con-
nected to form an interior cavity 17 for a container
18. Bottom 15 is narrower than top 14 and sidewalk
16a and 16b are inclined relative to vertical planes.
Container 18 is an open topped tray formed by
side walls 20 and 21 having end walls 22 and 23 se-
cured between opposite ends thereof and a bottom wall
24. Support ribs 25 or other suitable projections
extend upwardly from bottom wall 24 for supporting a
food product 30 spaced from bottom wall 24 to provide
space forming a path 28 extending between the lower
surface 31 of the food product 30 and the upper sur-
face 25a of the bottom wall 24 of container 18.
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P-15,094
8
The package 10 carries the food product 30 in the
open-top container 18 which is enclosed in the tube-
like sleeve 12, preferably constructed of cellulosic
or other poorly conductive material. The food product
30 is stored in a cabinet 170 in the container 18 in-
side of the sleeve covers 12. The container 18 is
withdrawn from the sleeve 12 prior to heating the food
product 30 and then the food 30 and container 18 are
returned to the sleeve 12 to retain heat in the food
until the package 10 is opened by the customer.
It should be readily apparent that refrigeration
of food product 30 may not be necessary if food prod-
uct 30 is not perishable or if package 10 containing
the food product has been treated to assure that food
product 30 has sufficient shelf life. Cabinet 170 may
be refrigerated or divided into compartments, some of
which are refrigerated depending upon the nature of
the food product to be dispensed by the vending ma-
chine 200.
The relatively non-conducting sleeve 12 serves as
a comfortable holder for the hot container 18 and. food
30.
The cover for the container 18, having a lip 19
which extends around the periphery of upper edges of
walls 20, 21, 22 and 23, is formed by the top 14 of
sleeve 12 to provide a slip-over lid which covers the
open top of the container 18 and can be removed for
heating and subsequently provides insulated cool han-
dling of the hot product 30 by enclosing the lip 19 of
the container 18.
In FIG. 9 of the drawing, the numeral 18a gen-
erally designates a modified form of the container
having a susceptor belt 27 mounted adjacent bottom 24
of the container having ribs 25 formed thereon. The
susceptor belt coating 27 is formed of
polyethylene
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P-15,094
9
terephthalate and is commercially available from a
variety of sources including Frigigold of England and
is recommended for use in reusable plastic or paper-
board microwave cook ware in a recommended temperature
range of up to 450'F. The susceptor belt 27 is rapid-
ly heated by microwave energy until it reaches a maxi-
mum temperature of, for example, 350'F and the temper-
ature level is maintained to provide. radiant and con-
ductive bottom heat to the food product 30.
In the embodiment of the container 18 illustrated
in FIG. 10 of the drawing, a layer 29 of a particu-
late food product, such as strips of pasta or slices
of potato, is positioned between the bottom wall 24 of
container 18 and the lower surface 31 of food product
30. If layer 29 is slices of potato and product 30 is
a meat product, juices dripping from the lower surface
of food product 30 will contact and be absorbed by
layer 29 of potato slices to enhance the cooking of
both the slices of potato and the meat product 30.
The liquid juices enhance the flavor and appearance of
the. potatoes while the circulation of air through
passages 28 between the potato slices results in con-
trolled drying and evaporation of moisture from the
bottom of the food product 30 to provide an acceptable
texture, taste, smell and appearance superior to that
conventionally achieved in microwave ovens.
As illustrated in FIGS. 15-21 of the drawing, the
food product 30a may comprise particulate material,
such as slices of fried potatoes and a corrugated
susceptor belt 27 is mounted adjacent bottom 24 to
form ribs 25. Since the susceptor belt 27 is control-
lably heated by the microwave and portions of the
upwardly extending ribs 25 contact the lower surface
of the food product, the structure simulates grilling
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- P-15,094
as well as allowing juices to flow into the area be-
tween the ribs.
Container 18b, illustrated in FIG. 15, is pro-
vided with a sheet 27a of a heat shrinkable film bond-
s ed to lip 19a for sealing the food product 30a in the
container 30b. A sheet 27a preferably formed of poly-
meric compounds and materials, for example, synthetic
thermoplastic resins of the type which are commercial-
ly available from E.I. DuPont de Nemours and Co. of
10 wilmington, Delaware, used to form a polyester film
which will melt when contacted by air at a temperature
of less than 400'F which results in film 27a becoming
perforated and rolling toward lip 19 which extends
around the periphery of container 18b. The cohesive
nature of the polyester material prevents it from
dripping into the food container. It should be readi-
ly apparent that the use of the polyester film 27a
provides a seal which prevents deterioration of food
product 30a over an extended period of time in a re-
frigerator or freezer.
A perforated grid or lattice 27b, illustrated in
FIG. 16 and FIGS. 18-21, may be mounted between the
upper surface of lip 19 and the lower surface of sheet
27a. Legs 27c and 27d spanning across the top of
container 18b support film 27a to assure that por-
tions of film 27a do not drop downwardly to engage the
food product 30a in container 18b.
As diagrammatically illustrated in FIGS. 18-21 of
the drawing, film 27a and lattice 27b are bonded or
otherwise sealingly secured to the lip 19 which ex-
tends around the periphery of the open top of contain-
er 18b to prevent dehydration and to otherwise protect
food product 30 in container 18b. Food product 30 is
supported on susceptor belt 27 having upwardly extend-
ing projections 25 formed thereon for spacing the
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P-15,094
11
' lower surface of food product 30 above the bottom of
container 18b to form air passages therebetween as
hereinbefore described.
As illustrated in FIG. 19 of the drawing, im-
pingement of air stream 28a against the upper surface
of film 27a causes a central portion of film 27a to be
perforated forming an opening 27a' in a central por-
tion of the film intermediate edges of container 18b.
As illustrated in FIG. 20, opening 27a' is en
larged as heat is transferred to the film 27a which
tends to roll back as indicated at 27a" as the film
material shrinks and is distorted.
As illustrated in FIG. 21 of the drawing, heat
transferred to the film 27a causes the meltable and
shrinkable film 27a to retract to the position desig
nated 27a " ' thereby uncovering the upper surface of
food product 30 in container 18b.
It should be appreciated that container 18b is
preferably stored in a tubular sleeve 12 of the type
hereinbefore described to prevent perforation of seal-
ing film 27a during handling of containers while. being
transported for stocking storage cabinet 170. As will
be hereinafter more fully explained, after container
18b has been moved into heat exchange relation with
streams 128a of heated air projected by air circulat-
ing apparatus 100, container 18b is reinserted into
the tubular sleeve 12 prior to dispensing the food
product to the customer so that the hot container 18b
and the food product 30 therein can be handled by the
customer to eliminate the necessity for providing "hot
pads" or other apparatus for handling the hot contain-
er.
As best illustrated in FIGS. 1 and 14, package
handling apparatus 40 includes a container loading
device 50 and a container unloading device 60. The
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P-15,094
12
loading device 50 and unloading device 60 are of sub-
stantially identical construction and comprise motors
51a and 51b, respectively, drivingly connected through
synchronous drive belts 52 to the end of drive screws
56. Each drive screw 56 has threads formed on the
outer surface thereof which engage internal threads in
a drive nut 55 which moves linearly along drive screw
56 as the drive screw rotates. Thrust is transmitted
from the drive nut 55 to a transitional tube 57. The
entire screw 56 and nut 55 assembly is protected from
contamination and environmental elements by a,cover
tube 58, and an end wiper seal 59.~ Rotational thrust
bearings 54 allow the screw 56 to freely rotate under
loaded conditions.
The electromechanical linear actuators 50 and 60
are commercially available from Jasta, Inc. of San
Jose, California and from Dayton Electric Manufactur-
ing Co. of Chicago, Illinois, and form no part of the
invention except in the claimed combination.
Motors 51a and 5Ib are preferably variable speed
reversible synchronous gear motors. It should be
readily apparent that motors 51a and 51b transmit
torque through belt 52 for rotating drive screws 56.
Rotation of drive screw 56 causes drive nut 55 which
is secured to the inner end of translating tube 57 to
move translating tube 57 to extend or retract tube 57
relative to cover tube 58.
As diagrammatically illustrated in FIG. 5 of the
drawing, electromechanical actuator 60 having rake
plate 57b mounted thereon is pivotally mounted between
a pair of lugs 60a and is rocked in a vertical plane
by a solenoid 60b connected to a.n actuating arm 60c
secured to cover tube 58 of actuator 60.
When rake plates 57b is in its retracted home
position indicated in dashed outline at 57b in FIG. 5
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P-15,094
13
of the drawing, rake plate 57b is preferably posi-
tioned at an elevation above container 18 such that
when translating tube 57 is extended to the full out-
line position, the lower edge of rake plate 57b moves
above the upper edge of container 18. When rake plate
57b reaches the full outline position illustrated in
FIG. 5 of the drawing, solenoid 60b is actuated for
moving rake plate 57b downwardly to an elevation below
the lip extending around container 18 such that when
translating tube 57 is retracted to the dashed outline
position, container 18 will be returned through pas-
sage 48 in product guide member 46 and returned to the
interior of tubular sleeve 12. After container 18 has
been deposited in tubular sleeve 12, solenoid 60b will
again be actuated for elevating rake plate 57b to a
position above the upper edge of opening 48 such that
pusher plate 57a may be actuated for moving the next
container l8 into the oven.
Conveyor 65 includes a flexible belt 66 extending
around a drive roller.66a and a driven roller 66b,
drive roller 66a being driven by a reversible variable
speed motor 68.
The in-feed conveyor, generally designated by the
numeral 42, comprises a paddle 43 suspended between
chains 43a and 43b which extend around drive sprockets
mounted on a shaft driven by a motor 43d. The in-
feed conveyor 42 is mounted between guide members 44
and 46. As illustrated in FIG. 5, guide member 44
comprises a generally L-shaped member formed by sub-
stantially perpendicularly disposed legs 44a and 44b
connected by a transition section 44c. Product guide
member 44 is connected to a second product guide mem-
ber 46 by a front bracket 42f and a rear bracket 42r.
As illustrated in FIG. 1 of the drawing, an in-feed
drive motor 43d is secured to guide member 46 and
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P-15,094
14
paddle 43 is moved between guide members 44 and 46 by
chains 43a and 43b.
Product guide member 46, best illustrated in FIG.
5, is formed by generally perpendicularly disposed
legs 46a and 46b connected by a transition section
46c. A third leg 46d extends generally parallel to
leg 46b and has an end secured to an end of leg 46b by
stop member 45. As will be hereinafter more fully ex-
plained, stop member 45 functions as a stop to limit
movement of package 10.
Leg 46b of product guide member 46 has a first
passage 47 formed therein while section 44d has a
second passage 48 formed therein. As will be herein-
after more fully explained, when conveyor 65 moves
package 10 into engagement with backstop 45, the open
end 13a of tubular sleeve 12 is positioned adjacent
opening 47 while the open end 13b of sleeve 20 is
positioned adjacent passage 48. When motor 51a of the
linear actuator of loader assembly 50 is energized,
tube 57 and push plate 57a on the end thereof will
move through passage 47 and through the open end 13b
of sleeve 12 for moving container 18 through the open
end 13a of sleeve 12 and through passage 48 into a
cooking chamber in oven 70. After container 18 is
positioned in the cooking chamber, motor 51a is re-
versed, thereby retracting translating tube 57 and
push plate 57a to the position illustrated in FIG. 1
of the drawing.
After the product 30 in container 18 has been
heated, motor 51b of the linear actuator of the un-
loading assembly 60 will be energized to extend the
translating tube 57 of the unloading assembly 60 caus-
ing the rake plate 57b to move into the cooking com-
partment above container 18 and then pivot downwardly
for engaging lip 19 on end wall 21 on container 18.
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' P-15,094
Motor 51b is then reversed for retracting tube 57 and
rake plate 57b for urging container 18 out of the oven
70, through passage 48 and through the open end 13a of
sleeve 12. When motor 68 is energized, the heated
5 food product 30 in container 18 which has been reposi-
tioned in sleeve 12 will be moved toward the delivery
end of conveyor 65.
Product guide members 44 and 46 are bolted or
otherwise secured to the upper surface of loader base
10 member 42a upon which in-feed conveyor 42 and delivery
conveyor 65 are mounted.
The oven 70 comprises spaced side walls 72 and
74, a back wall 76 and a front wall 78. Front wall 78
has an access opening 79 formed therein which is open-
15 ed or closed by a door 80. A microwave trap 81 is
formed around door 80 and is configured to prevent
passage of microwave energy through space between the
periphery of the door 80 and walls of the cabinet 70.
Top wall 71 and bottom wall 73 close upper and lower
ends of oven 70. Each wall of the oven is preferably
formed by spaced metallic sheets and the space between
the sheets is filled with thermal insulation material.
An actuator 82, secured to mounting bracket 82a,
is connected through a link 84 to door 80 for moving
door 80 vertically relative to access opening 79.
Actuator 82 is preferably an electromechanical actua-
tor of the type illustrated in FIG. 14 and is driven
by a motor 51a.
Referring to FIGS. 1 and 2 of the drawing, elec-
tromagnetic radiation device generally designated by
the numeral 90 in the illustrated embodiment comprise
a pair of magnetrons 92 connected to wave guides 93
formed in side walls 72 and 74 of oven 70. The magne-
trons 92 supply electromagnetic energy to wave guides
which carry the energy to the cooking chamber. A
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16
preferred microwave frequency is 2450 megahertz.
Magnetrons 92 are conventional vacuum tubes in the
microwave oven that convert electrical energy to elec-
tro magnetic energy in the microwave frequency spec-
s tram. Waves of microwave energy are similar to radio
waves except they are higher frequency than radio
waves lower frequency than ordinary light waves. The
microwave energy is channeled through wave guides 93
from the magnetrons 92 into the cooking chamber 120.
As illustrated in FIG. 2 of the drawing, the side
walls 72 and 74 are formed by spaced sheets 74a and
74b and insulation material 74c is configured to form
a guide tube 93 having a lower end 94 which is in-
clined at an angle 95 relative to a vertical plane 96
at an angle in a range between 15' and 75'. In the
illustrated embodiment, the angle 95 is approximately
45'.
The application of microwave radiant heating is
delivered from two sides and angles downwardly toward
food 30 in an open top container 18. Since the con-
tainer and the food in the container do not reflect
microwave significantly and since the space under the
container diffuses microwave which passes through or
by the container the beam from one wave guide is not
reflected directly into the other but is largely re-
tained in the heating chamber.
Since the container 18 is non-metallic reflec-
tions from one wave guide 93 are not reflected into
the other to keep microwave in the chamber 120 to
effectively heat the food 30.
The support for the open package is preferably
less than 25~ reflective of the microwave.
The reflective surface of the bottom 24 of the
container 18 is greater than one-fourth wave length,
for 2450 megahertz (MHZ) microwave one-fourth of 13
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17
cm, below the surface of food being heating. The
angle and the distance reduce standing waves in the
small heating cavity.
A tube 103 is connected through a valve 103a to a
supply of water or steam and which may be used for
delivering an atomized spray of water or steam into
the air conditioning chamber 115 for controlling the
relative humidity and dew point of air circulated
through air conditioning chamber 115 and cooking cham-
ber 120.
Referring to FIGS. 2, 3 and 4 of the drawing, air
circulating apparatus generally designated by the
numeral 100 comprises a blower housing 102 having an
inlet opening 104 and a discharge opening 106. As
illustrated in FIGS. 2 and 4, blower housing 102 is in
the form of a volute and a plenum section 108 is form-
ed adjacent the discharge opening 106.
A radial flow fan impeller 110 draws air axially
through inlet opening 104 and discharges air radially
through plenum section 108 and discharge opening 106.
A heating element 112 having coils 113 of a first
stage and coils 114 of a second stage is mounted for
heating air drawn into the blower housing 102.
As best illustrated in FIG. 3 of the drawing, the
interior of the cabinet 70 is divided by a perforated
plate 75 to form an air conditioning chamber 115 and a
cooking chamber 120. Perforated plate 75 is con-
structed of a metallic material and has perforations
76 with relatively small openings equivalent to more
than 50~ of the surface area. The perforated metal
sheet 75 prevents microwave energy from passing into
the air conditioning chamber 115.
As best illustrated in FIG. 3 of the drawing, the
first stage of coils 113 is mounted in air condition-
ing chamber 115 outside of the blower housing 102
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18
while the second stage 114 of coils is mounted inside
blower housing 102. Terminals 112a and 112b of heat-
ing element 112 are connectable to a suitable source
of electricity.
As illustrated in FIG. 4 of the drawing, a mount-
ing plate 116 having a notch 117 formed in the periph-
ery thereof and a central opening 118 is bolted or
otherwise secured to blower housing 102 for supporting
heating element 112. Plate 116 is formed in two parts
which are connectable along a part line 119.
As illustrated in FIG. 3, blower 110 is mounted
on a shaft which is driven through a coupling 111 by a
motor 110a.
Coils 109 of a third stage heating element 109 is
mounted in the plenum section 108 of blower housing
102 and positioned such that air delivered radially
from blower 110 is heated immediately prior to being
delivered through discharge opening 106. It should be
readily apparent that only coils 109 may be activated
while coils 113 and 114 are idle, if it is deemed
expedient to do so depending upon the heating require-
ments of a particular food product.
An air dispensing duct generally designated by
the numeral 125 is secured to plenum 108 for receiving
air from discharge opening 106.
As best illustrated in FIGS. 3 and 4 of the draw-
ing, air dispensing apparatus 125 comprises a tapered
duct formed by a perforated plate 126 having an array
of passages formed therein which communicate with
tubes 128. A front wall 130 and a rear wall 132 ex-
tend upwardly from the perforated plate 126 and are
connected between side walls 134 and 136. An inclined
top wall 138 extends between front wall 130 and a
flange 140 encircling the lower end of duct 108 and
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19
enclosing the discharge opening 106 from the blower
housing 102.
As illustrated in FIG. 3 of the drawing, air
directing vanes 142 extend between side walls 134 and
136 of the tapered duct for distributing air along the
length of the interior 144 of the tapered duct.
The air dispensing apparatus 125 is pivotally
secured to duct 108 by a pivot pin 142 extending
through aligned apertures 144 in flange 140. Pivot
pin 142 extends into an opening 145 formed in lug 146
on shaft 148 which extends into an aperture 149 on a
link 150. Link 150 has an elongated slot 152 formed
therein into which a pin 154 on crank 155 extends.
Crank arm 155 has an aperture which receives a
drive shaft 158 driven by motor 160 through a gear
reducer 161.
A radial blower 110 discharging its highest ve-
locity air from the outer portion of the volute down-
wardly through shaped openings in tubes 128 to impinge
upon a narrow food product 30 in the open top contain-
er 18.
The air dispensing duct 125 is moved relative to
the product 30 to give uniform coverage by the air
streams. As best illustrated in FIGS. 11 and 12, the
sides 22 and 23 of the container 18 cause a portion of
the air stream to be deflected to heat the sides and
bottom 31 of product 30 in the container. The move-
ment applies the air streams near one side of the con-
tainer adjacent side wall 22 and then to the other
side adjacent side wall 23 so that parts of the air
streams are alternately applied to opposite exposed
sides of the product 30 and are caused to alternate
the lateral flow through loose stacks of food products
30 such as curled or random lengths of french fried
potatoes. This alternating lateral air flow through
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paths 28 between support ribs 25 passes under and
heats the lower side 31 of irregularly shaped prod-
ucts such as bone-in chicken parts.
The effectiveness of the sideways air heating of
5 lower surfaces 31 can be enhanced by ribs 25 to pro-
vide air passages under flat products.
Further, the moving air dispensing apparatus 125
provides moving reflective surfaces which serve as
stirrers to help distribute the microwave energy in
10 the cooking chamber 120.
The combination of extended orifices through
tubes 128, and the open top container 18 provides air
escape path 129 while bringing the orifice to an opti-
mum distance from the product 30. It should be noted
15 that upper edges of the sides 20 and 21 and ends 22
and 23 of container 18 extend above the height of. the
contained product 30 to enhance air flow between the
lower surface 31 of the product 30 and the bottom 24
of container 18.
20 As illustrated in FIG. 2 of the drawing, streams
of air dispensed from air dispensing duct 125 through
hollow air dispensing tubes 128 impinge upon the upper
surface of a food product 30 in container 18. The
spent air travels through space 129 between tubes 128,
as illustrated in FIGS. 11 and 12 of the drawing.
Spent air travels upwardly adjacent baffles 162 and is
then directed downwardly by a curved surface 164 along
a path between baffle 162 and baffle 166 downwardly
toward soil collector pans 165. Soil collector pans
165 are preferably removably mounted and are main-
tained at a temperature which is less than the temper-
ature of any other surface in the oven 70 for causing
very fine smoke-type particles in the moving air to be
collected on the coldest surface in the recirculating
path. From soil pans 165 the recirculating air is
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21
directed upwardly between the outer surface of baffle
166 and sheet 74b of side wall 74 upwardly through
passages formed in the perforated plate 75.
Baffles 162 and 166 are preferably constructed of
material which is relatively transparent to microwave
energy. To assure that the soil collection pans 165
are maintained cooler than other surfaces in oven 70,
the pans may be exposed to outside air or water cool-
ing to facilitate collecting aerosol from the recircu-
lating air.
From the foregoing it should be readily apparent
that the disclosed method for controlling the tempera-
ture and surface texture of a food product which is to
be delivered from vending machine 200 generally com-
prises delivery of a suitably packaged and
preserved
food product from a storage compartment 170 to an oven
70. The package 10 is positioned by back stop member
45 in a predetermined relationship relative to elec-
tromechanical linear actuators 50 and 60 and relative
to access opening 79 communicating with cooking cham-
ber 120 in oven 70.
Actuation of the actuator of the loading device
50 results in movement of push plate 57a through tubu-
lar sleeve 12 for pushing container 18 out of sleeve
12 and into the cooking chamber 120. Streams 28a of
air delivered through tubes 128 of the air circulating
apparatus 100 melts and shrinks film 27a for uncover-
ing food product 30 in the open top container 18.
In the embodiment illustrated in FIG. 15 of the
drawing, one or more air streams 128a, after causing
the food product 30a in container 18 to be uncovered
will be delivered through the open top of container
18b. If the food product 30a in the container is
strips or slices of pasta, potatoes or other particu-
late material, air from stream 128a will be delivered
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22
through the stacked material in heat transfer relation
with the surface of the pieces of the food product.
If food product 30 is a solid article as desig-
nated by the numeral 30 in FIGS. 11 and 12 of the
drawing, air dispensing duct 125 is preferably rocked
causing air streams 128a and 128b to move across the
surface of the food product between lateral edges
thereof such that regions of controlled air pressure
are alternately formed adjacent opposite sides of the
product 30 such that temperature controlled air flows
through passage 28 between the lower surface 31 of the
food product and the upper surface 25a of the bottom
24 of contair_er 18.
After the surface of the food product 30 has been
heated by air streams 128a and 128b, the recirculating
air tends to limit localized heating of the product by
microwave energy delivered by magnetrons 92. Tips,
and thin areas of the product which are rapidly heated
by the microwave energy may actually dissipate heat to
air in streams 128a and 128b to provide cooling to
certain portions of the food product.
After the food product 30 in container 18 has
been sufficiently heated, air flow through the air
circulating apparatus 100 is terminated, magnetrons 92
are turned off and blower actuator 82 is energized for
moving the door upwardly to the position illustrated
in FIG. 1 of the drawing. The electromechanical ac-
tuator of the container unloading device 60 is then
actuated for moving rake plate 57b from the dashed
outline position in FIG. 5 of the drawing to the full
outline position. Rake plate 57b is then lowered and
retracted for moving container 18 out of the oven and
redepositing the hot container and the food therein in
the tubular sleeve 12.
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23
After the heated food product and container 18
have been moved into the protective tubular sleeve 12,
conveyor 65 is energized for moving the heated food
product toward the delivery passage 124 of the vending
machine 200 such that the product is accessible to the
customer by opening protective door 225.
