Note: Descriptions are shown in the official language in which they were submitted.
W096/08190 ~ PCT/GB95/02168
1
FOOD DISPENSING SYSTEM
TECHNICAL FIELD
This invention relates to a food dispensing system. In particular it is
concerned
with a system for dispensing food in discrete batches where a temperature
difference from ambient needs to be maintained for at least some if not all of
the
food in each batch.
The dispensing of food is frequently required in an establishment, such as a
hospital, where food prepared in one place has to be transferred and dispensed
on
trays to individuals or groups of individuals located at some distance from
the
point of preparation. A similar requirement arises in aircraft catering. To
ensure
that food is effectively transferred a number of requirements must be met. The
prepared food, whether hot or cold, needs to be moved from a kitchen or other
food preparation area to the location of each consumer while being protected
fmm
contamination and deterioration and while being maintained within a
predetermined temperature range. Once on location the food temperature are
appropriately raised or lowered to the temperature at which it is to be
consumed.
The cabinet is then opened and the tray presented on a tray along with the
necessary eating utensils.
Broadly food dispensing requires that regardless of the method of food
preparation
or storage for the purpose of consumption at least some of the food on the
tray
will need to either above, at or below room temperature. The provision of this
will
be discussed further hereafter.
Once each tray has been used the tray along with utensils, and any waste food,
need to be readily recovered from each consumer and then returned to a service
area or kitchen to enable the hardware to be cleaned for re-use and waste
material
disposed o~
Any dispensing system that is used should be user friendly so as to enable
food
WO 96108190 ~'~~ PCTIGB95102168
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and utensils to be readily dispensed and recovered without the need to
exercise
time consuming manual or technical skills. Typically nursing staff who
frequently
have to deal with the provision of meals should be able to use the system
readily
without significant intrusion into other more critical and specialised
functions. On
aircraft large numbers of people need to be supplied with food and the used
trays
recovered by a relatively small number of cabin staff promptly and in a
controlled
manner.
BACKGROUND ART
In one prior art device a dispensing system makes use of a food serving tray
is
known (UK Patent 1 486 939) incorporating heater elements to enable food to be
maintained art a desired serving temperature. The tray comprises a planar
support
member of thermal insulating material having an upturned peripheral edge. The
support member has at least one interruption closed and sealed by a plate or
disc
of heat conducting material. Each plate or disc is contacted on its underside
by a
heater housed in the tray which is powered by way of conductors also housed in
the tray which conductors extend from the heater to the edge of the tray to an
array of electrical contacts. A trolley for housing the trays is equipped with
a
complementary array of contacts so that with the tray installed in the trolley
the
individual heaters in each tray are powered by way of the coupled array to
maintain the heater in the tray at operating temperature. A tray of this kind
while
being useful for heated food is not useful for unheated or chilled food. In
addition
the trays are elaborate units requiring use with a trolley having a
complementary
electrical supply and connecting system. Both the trays and their trolley
require
careful maintenance and cleaning.
In a second prior art device (US Patent 4966296) there is provided an
integrated ,
food tray incorporating a tray housing. The housing is in the form of a
receptacle
which is initially integrated but which contains at least two meal course
portion
containers which are separable. At least one separable portion is designed to
carry
a meal course which is to be heated in that portion, and at least one
separable
portion is not intended to be heated but rather is intended to carry a meal
course
CA 02176371 2001-07-12
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which is to be served at room temperature or at a temperature cooler than room
temperature.
The integrated food tray described while providing for the selection, transfer
and heating of the
food does not actually facilitate the presentation of the prepared food to a
consumer. For this
purpose a further tray is required. Once used the separable portion containers
become waste
material and consequently the person serving the food has to gather up the
used containers and
deposit them into a waste earner. As a result a considerable amount of waste
material is
generated in the course of using this tray system.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a food disx>ensing
system comprising a
cabinet having an interior volume adapted to receive an array of at least one
tray with a vertical
spacing between the tray and another tray or another part of the cabinet, the
tray having a
removable freely locatable divider thereon, the divider having a height
comparable to the
vertical spacing between the tray and another tray or another part of the
cabinet so that the
divider isolates a first region of the tray from a second region of the tray.
According to a first preferred embodiment of the present invention, the
divider forms a thermal
insulation barrier between the first region and the second region.
According to a second embodiment of the present invention, the first region is
adapted to be kept
at a higher temperature than ambient by means of heat exchange; with a source
of heat in the first
region or in good heat exchange with the first region. Typically., the source
of heat may be: a
powered heater from which heat is dispensed to by heat transfer to a flow of
air and subsequent
heat transfer from the heated flow of air to the first region; or a 1>owered
microwave heater; or an
unpowered source of heat such as previously heated material typically in
pellet or block form; or
a combination of one or more of these.
CA 02176371 2001-07-12
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According to a third preferred embodiment of the present invention, the second
region is adapted
to be kept at a lower temperature than ambient by means of heat exchange with
a cooling means
in the second region or in good heat exchange with the second rf;gion.
Typically, the cooler
means may be: a powered refrigerating unit from which cooling; is dispensed by
heat transfer to
a flow of air and by subsequent heat transfer from the cooled air to the
second region; or an
unpowered source of cooling such as previously cooled material typically in
block form; or a
combination of these.
According to a fourth preferred version of the present invention, heating or
cooling of the first
and second regions are regulated by means of a controller.
According to a fifth preferred version of the present invention, the divider
incorporates a heat
exchanger.
According to a sixth preferred version of the present invention, the first
region of each tray in the
cabinet are enabled to communicate with each other by means of a first
flowpath and air is
displaced around the first flowpath to provide for all first regions to be
maintained at a similar
temperature either by natural convection or forced convection or a combination
thereof.
According to a seventh preferred version of the present invention, the second
region of each tray
in the cabinet are enabled to communicate with each other by means of a second
flowpath and
air is displaced around the second flowpath to provide for all second regions
to be maintained at
a similar temperature either by natural convection or forced convection or a
combination thereof.
According to an eighth preferred version of the present invention, the cabinet
is adapted for
mobile operation.
CA 02176371 2001-07-12
According to a ninth preferred embodiment of the present invention, the
cabinet is equipped
with means for coupling the cabinet to an external source of power.
The present invention provides for a food dispensing cabinet particularly for
mobile operation
where a simple form of tray can have first and second regions of any relative
proportions defined
on its working surface by means of a removable and freely locatable divider
and appropriate
amounts of food placed in each region. On inserting the tray anal its contents
into the cabinet,
the divider interacts with a tray or part of the cabinet above it so as to
isolate and insulate the
first and second regions of the tray from each other.
Thereafter as appropriate the food in the first region is maintained at a
temperature above
ambient in a number of ways depending on what is convenient. Typically a
preheated block can
be installed in the cabinet at a location which is in good heat exchange
contact with the first
region of some or all of the trays. The cabinet is provided with an insulated
layer at or near the
outside of the cabinet to minimise the flow of heat from the firsl: region.
The divider serves to
prevent the flow of heat from each first to each second region. Alternatively
heating can be by
way of a powered heater element such as individual radiant elements or by way
of a microwave
source. In this case if the cabinet is not filled with loaded trays then only
elements in the vicinity
of loaded trays need to be operated. In yet another arrangement a fan is used
to generate heat
transfer by forced convection or natural convection to provide fir
circulation.
Again as appropriate the food in the second region can be maintained at a
temperature below
ambient. Typically a pre-cooled block can be installed in the cabinet at a
location which is in
good heat exchange relationship with second region of some or all of the
trays. The divider
serves to minimise the flow of heat into the second region so seining to keep
the temperature of
cooled foodstuffs at the required level. Alternatively cooling can be by way
of a refrigeration
unit incorporated in the cabinet which provides cooled air for circulation by
forced or natural
convection or a combination thereof.
CA 02176371 2001-07-12
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The invention further enables flow guide means to be located so as to provide
a first flowpath
passing through the first regions to enable a flow of heated air to be
circulated around the first
path to provide for the close control of the temperature of food lLocated in
each first region.
Likewise flow guide means can be located so as to provide a second flowpath
passing through
the second regions to enable a flow of cooled air to be circulated around the
second path to
provide for the close control of the temperature of food in each second
region.
The invention particularly lends itself to food regeneration processes where
prepared food stored
at a central location can be loaded in appropriate amounts onto trays, the
burners installed on
each tray and the cabinet duly loaded. The temperatures of food stored in the
trolley can be
closely controlled and a suitable temperature change applied for a
predetermined period to
enable the food to be dispensed from the trolley to the recipient;> in optimal
condition.
The invention facilitates the dispensing process by providing for a tray to be
withdrawn from the
array in the cabinet, for the divider to be readily removed and stacked on top
of the cabinet and
for the tray to be then handed to the consumer. Once the used tray is
recovered a divider can be
recovered from those available on the cabinet top and placed on the tray and
the combination is
then inserted back into the cabinet.
The used trays and the dividers being of a simple form are readily handled and
cleaned prior to
re-use. In addition the interior of the cabinet is uncomplicated and is
readily cleaned.
BRIEF DESCRIPTION OF DRAWINGS
An exemplary embodiment of the invention will now be described with reference
to the
accompanying drawings of a mobile hot and cold cabinet for dispensing food of
which:
Figure 1 is a plan view; and
W0 96108190 PCT/GB95/02168
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Figure 2 is a vertical section on section II-II of Figure I;
MODE FOR CARRYR~1G OUT THE INVENTTON
This embodiment shows means for establishing air flow paths over the frays.
Cabinet 51 serves to house frays T10 to TI3. The cabinet 51 has a door 52 to
provide access to working volume 53 containing the trays T10 to TI3. Chamber
54
has a first section 55 and a second section 56 separated by a flap 57. The
flap 57
can be used to link or isolate the sections 55, 56 as required.
Simple barriers are used to define particular air flow paths over the trays.
Typically divider 63 on tray T11, divider 64 on tray T12 and divider 65 on
tray Ti3
are used to separate and to insulate from one another two regions of each fray
into
a hot region I (generally on the left hand side of the partitions as shown in
Figure
2) and a cool region II (on the right hand side of the partitions shown in
Figure 2).
The dividers 63, 64, 65 extend from the front to the back of their respective
frays
and are similar in height to the clearance above each tray and the tray or
compartment roof above so as to prevent cross flow from one region of a tray
to
another and to thermally insulate the two regions.
By providing barriers 63, 64, 65 as close fitting dividers air bleeds from the
hot to
the cold side are kept to a minimum if not eliminated. The dividers 63, 64, 65
are
conveniently fabricated from any of a number of plastics materials.
First section 55 contains a tangential fan 58 and parallel heating elements
59. On
operation of fan 58 air passes out of the first section 55 into working volume
53 by
way of a vertical series of apertures A1 to A4 and passes over each tray
before
returning to first section 55 by a second series of vertical apertures Bl to
B4.
Second section 56 provides a second tangential fan 60 and parallel evaporator
elements 61 similar in form and function to fan 41 and condenser 40 described
in
connection with the first embodiment. Air passes out of the second section 56
into
WO 9610819D ~ $ PCT/GB95102168 I
working volume 53 by way of a verricaI series of apertures Cl to C4 to pass
over
each tray before returning to second section 56 by way of a fourth series of
vertical
apertures Dl to D4.
Typically in this case tray TIl contains three food containers 66, 67 which
are to be
kept warm and a further container 69 which is to be kept cool.
To use the cabinet 5I the trays T10 to T13 are loaded with food and dividers
63,
64, 65 are positioned to divide the tray up into hot and cold regions. By
being
separate items the dividers allow for the relative sizes of the hot and cold
regions
to be readily set at the time the food is added to the tray. Consequently each
loading can be set up to make the most efficient use of the heating/cooling
systems. The trays are then inserted in the cabinet. In this case both heating
and
cooling are required. However the system allows of extremely flexible
operation.
Typically food in a given region can at choice be heated, left at ambient
temperature, or cooled. In the present case the flap 57 is moved to isolate
the first
section 55 from the second section 56.
The first fan 58 and second fan 60 are energised together with the heater
elements
59 and evaporator elements 61. As a consequence heated air is generated in
first
section by way of elements 59 and is driven by the first fan 58 out through
each
aperture A1 to A4 into working volume 53 to pass over a food tray, so
supplying
heat to food containers requiring it before passing back into the first
section 55 by
way of apertures Bl to B4 where it is reheated for further circulation. Cooled
air
circulates from second section 56 into working volume 53 by way of each of
apertures Cl to C4 into working volume 53 to pass over a food tray so removing
heat from food containers located in the cooling air path before passing back
into
second section 56 by way of apertures Dl to D4.
INDUSTRIAL APPLICABILITY
The embodiment provides for food on a conventional tray to be readily
maintained
at a predetermined temperature by the use of simple barrier in combination
with
i W096/08190 PCT/GB95/02168
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an air circulating system which provides a paralleled arrangement of air flows
over each tray in a vertical array thereof. The use of a tangential fan for
generating
air flow around a closed path provides a relatively quiet method of displacing
air
' as against a conventional bladed fan. The use of a tangential fan also
enables the
cabinet and associated equipment to form a relatively compact package. The
only
external connection needed for the cabinet is to a mains power supply.
A programmer including a microprocessor can also be used to enable the heating
and/or cooling flows and their temperatures to be governed in accordance with
a
predetermined program depending on the way the food is to reach its required
dispensing temperature. Given the food has reached its required temperature
the
use of an insulated cabinet insures that temporary disconnection form a mains
power supply to enable the cabinet to be moved and connected to a fresh power
supply is readily undertaken without the food temperature changing
significantly.
In yet another embodiment a cabinet similar in most respects to that described
in
connection with Figures I and 2 is provided but with no built in heater such a
parallel heater elements described in connection with Figures I and 2. Instead
the
heat is provided by way of electrical heating elements incorporated in each
movable divider, similar to dividers 63, 64, 65. Each divider is provided on
its
inner end with a pair of projecting electrical contacts. The rear of the
cabinet is
equipped with a shrouded bulbar arrangement complementing the layout of the
contacts so that the action of pushing a divider into place on a tray causes
the
contacts to engage the bulbar and so provided for the energisation of a heater
element in the divider. Where a divider equipped with a heater serves to
separate
a warmed region of the tray from a cooled region the divider incorporates
insulation to limit the passage of heat to the cold side of the divider. The
use of
heating dividers of general type described ensures that the minimum amount of
power is used since heat will only be generated in relation to the one tray on
which it is used. Consequently it provides for efficient use of a cabinet
which
carries less than a full complement of food bearing trays.
A number of ways have been described of providing for flows of warmed air
WO 96/08190 PCTIGB95102168
and/or cooled air over specific areas of one or more trays in an array. In
general
terms the or each discrete flow areas of each tray can be defined either by a
barner
on the tray. The use of a tangential fan provides for the efficient
circulation of air
on two or more flow paths in parallel. The fans and power supplies to the fans
and the heating or cooling heat exchangers are located in the cabinet but are
well
protected from the working region in which the tray array is located. The
mobile
versions of the cabinet systems are readily supplied with electrical power by
a
wandering lead and the insulation of the cabinets ensure that heat loss or
gain is
minimised while the cabinet is disconnected from a power source while being
food
is being dispensed from it on a working route such as around a hospital ward.
The invention also provides for a cabinet dispensing with a need for an
external
power supply. This is achieved by equipping the interior of the cabinet with
housings for hot and cold materials. Typically heated blocks or pellets of
heat
retaining material are located so as to readily supply heat to each first
region by
natural convection/radiation. Chilled blocks of known type are located so as
to
readily cool each second region by natural convection. In either or both cases
a
battery powered fan can be used to provide air circulation for each region or
set of
regions.
