Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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REFRIGERATION UNIT FOR COLD SPACE MERCHANDISER
FIELD OF THE INVENTION
This invention relates to a merchandising display cooler of the kind which
is used in convenience stores, snack bars and restaurants for storing and
cooling drinks, particularly carbonated beverages provided in cans. Typically,
merchandising coolers have a vertical display area which is visible to the
consumer through glass doors which may be hinged or which may slide for
easy access to the display shelves. More particularly, this invention relates
to
the refrigeration unit used for cooling the merchandiser and to the resultant
air-flow distribution in the merchandiser required to maximize cooling
efficiency.
It will be understood that the refrigeration unit and air-flow distribution
will also find application in the cooling of freezer cabinets used for food
products.
BACKGROUND OF THE INVENTION
As in all refrigeration units, a merchandising cooler will comprise an
evaporator assembly and a condenser assembly arranged in a closed circuit
such that coolant (typically Freon) is pumped to the evaporator assembly
where a fan distributes incoming return air from the cabinet interior over an
evaporator coil with the result that cooler air emerges from the evaporator
coil and is distributed into the interior of the cabinet while gaseous coolant
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is withdrawn from the evaporator coil and condensed to repeat the cycle.
Commonly, the condenser and evaporator assemblies are located inside the
walls of the cabinet comprising the merchandiser and are positioned separately
and remotely from each other, most commonly with the condenser assembly
located in the base of the cabinet and the evaporator assembly located in the
top of the cabinet. The origins of this arrangement are partly historical in
that condensers and evaporators were often provided by respective suppliers
who did not design their units to cooperate with each other. It thus became
convenient to locate them separately and to complete the assembly after
installation in the cabinet by providing appropriate electrical connecting
means and tubular conduits for coolant flow between the condenser assembly
and the evaporator assembly. The afore-mentioned "split system" has
inherent disadvantages which are apparent during assembly and servicing of
the cooler cabinet. It will be appreciated that the assemblies cannot be
tested
until fully installed in the cabinet and that, if any problems are discovered,
the entire cabinet must be accommodated so that it can at least be partially
disassembled and retested. Similarly, when a merchandiser which has been
in use is found to be defective, the entire cabinet must be put out of service
in order to carry out the appropriate repairs.
In order to overcome the previously-stated problems, modular refrigeration
systems have been developed in which the condenser and evaporator
assemblies are mounted on a common platform which can be easily removed
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from the cabinet for repair or replacement. Modular units have usually been
positioned in the top of a vertical cabinet, thereby taking advantage of
natural
convection forces in which the warm return air naturally rises to flow over
the evaporator coil and the cool air emerging from the evaporator coil falls
into the cabinet.
It has been found that top-mounted modular units have some disadvantages
which may be overcome by locating a refrigeration unit at the bottom of the
cooler cabinet. While the forces of natural convection within the cabinet do
assist the refrigeration process, these forces of course still operate outside
of
the cabinet where hot air rises and the ambient temperature surrounding the
refrigeration unit at the top can sometimes be significantly higher than the
ambient temperature at the bottom of the cabinet. It has therefore been
recognized that placing a modular refrigeration unit at the bottom of the
cabinet may result in a more efficient operation of the refrigeration unit.
Servicing of the refrigeration unit is also easier because it is more
accessible
at the bottom of the cabinet than at the top where a ladder may be required
to reach the refrigeration unit. Depending on the nature of the location in
which the cabinet is used, there may also be a cleaner air-flow circulation
around the compressor positioned at the bottom of the cabinet. Finally, the
resultant raising of the vending platform is usually considered an advantage
because the consumer is less likely to want to stoop down to reach a product
on a bottom shelf than to stretch to reach a product on a higher shelf. It has
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also been found in field tests that the noise emanating from a refrigeration
unit placed near the bottom of a cabinet is dissipated and is less of an
intrusion on the consumer than when the refrigeration unit is placed near the
top of the cabinet.
In spite of these advantages, bottom-mounted modular refrigeration units
have enjoyed relatively little commercial success. Applicant has recognized
the aforementioned advantages of a bottom-mounted modular refrigeration
unit and redesigned the unit so that it is easier to manufacture and to
service
and its cooling efficiency is improved thereby meeting stringent new standards
imposed by major beverage manufacturers whose products are displayed in
merchandisers of this kind.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, there is provided a
modular refrigeration unit for use in an insulated cabinet, the refrigeration
unit comprising a condenser assembly mounted to one side of a bulkhead and
an evaporator assembly mounted to the opposite side of the bulkhead, the
bulkhead and the cabinet being adapted to sealingly engage with each other
so as to define an insulated compartment for containing the evaporator
assembly. The condenser assembly will include conventional components
comprising a compressor, a motorized fan, heat exchanger, condenser coil and
condensate tray, operatively connected to each other to receive coolant from
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the evaporator assembly and return the coolant to the evaporator assembly
in a condensed form. The evaporator assembly comprises an evaporator coil
associated with a fan which directs warmer return air from the cabinet over
the evaporator coil so that the emerging cool air is forced into the cabinet
for
distribution.
In accordance with another aspect of the invention, a back wall of the
cabinet is spaced from an inner back panel which extends along the height of
the interior of the cabinet, the space between the inner back panel and the
back wall being vertically divided to define a central vertically extending
air
passage for cold air flow and two outer vertically extending air passages for
return air flow, the evaporator assembly being disposed inside the cabinet so
that cool air emerging from the evaporator assembly will enter the central
cold air passage. The cold air passage discharges cold air into the cabinet at
selected locations defined by openings formed in the inner back panel.
Preferably, the openings defining a cold air exit are located at the top of
the
cabinet and about midway between the internal floor of the cabinet and the
top. Openings disposed at selected locations on the inner back panel allow
ambient air from within the cabinet to flow into the return air passages where
it is aspired by the fan associated with the evaporator assembly to flow over
the evaporator coil. Preferably, the openings defining the return air inlets
are
located adjacent to the interior floor of the cabinet.
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In accordance with a further aspect of the invention, the bottom of the
cabinet comprises an evaporator pan which is formed with a well to collect
any condensate forming on the evaporator coil, the well having a drain hole
disposed to discharge the condensate to a condensate tray disposed on the
other side of the bulkhead separating the condenser assembly from the
evaporator assembly. Warm ambient air flowing through the condenser
assembly and warm coolant from the evaporator assembly are used to
advantage in evaporating condensate and spilled liquids collected in the
condensate tray.
In yet another aspect of the invention, a condensate tray is provided with
means to support a condenser coil which receive coolant from the
compressor, the supporting means being adapted to space the condenser coil
from the operative upper surface of the condensate tray so as to minimize any
abrasion between the coil and the tray arising from vibration in the coil.
Preferably, the tray will comprise a series of projections which may be
integrally formed with the tray and to which support means are attached
comprising a pair of oppositely-directed arms, each having a termination
adapted to cooperate with a loop of the condenser coil. In a preferred
embodiment of the invention, the terminations have a concave upwardly-
directed section adapted to cradle and receive loops of a condenser coil
having
a serpentine configuration. Not only is direct contact between the condenser
coil and the tray avoided, the tray may be released from the condenser
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assembly for easy cleaning and servicing.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be more clearly understood, a preferred
embodiment is described below with reference to the accompanying drawings,
in which:
Fig. 1 is a cross-sectional view through a merchandising display cooler in
accordance with the invention;
Fig. 2 is a cross-sectional view taken on line 2-2 of Fig. 1;
Fig. 3 is an enlarged view of circled area 3 in Fig. 1;
Fig. 4 is a partly-sectioned view taken on line 4-4 of Fig. 1;
Fig. 5 is a perspective view from the front of the condenser assembly,
partly exploded to reveal a condensate tray;
Fig. 6 is a cross-sectional view taken on line 6-6 of Fig. 5;
Fig. 7 is a perspective view from the rear of the evaporator assembly,
partly exploded to reveal an evaporator pan;
Fig. 8 is a graphical representation showing an average temperature profile
inside the cooler over a 20-hour period.
DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS
Referring firstly to Figs. 1 and 2, a merchandising display cooler made in
accordance with the invention comprises a cabinet generally indicated by
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numeral 20 having the following insulated walls: top wall 22, back wall 24,
right side wall 26 (as drawn), left side wall 28 (as drawn), and bottom wall
30.
An insulated interior floor 32 is vertically spaced from the bottom wall 30 so
as to accommodate a refrigeration unit therebetween. A transparent door 34
is hinged to one of the side walls 26, 28 and covers the front opening of the
cabinet 20 defined by the top wall 22, side walls 26, 28 and the interior
floor
32. A peripheral seal 36 mounted to the door 34 keeps the interior of the
cabinet 20 airtight and a light fixture 37 mounted to the top wall 22 adjacent
the door 34 is provided to light the interior of the cabinet 20.
The bottom wall 30 extends forwardly from the back wall 24 only
partially across the width of the cabinet 20 where it terminates in a raised
portion 38 extending upwardly directly opposite from a second raised portion
40 extending downwardly from the interior floor 32. An insulated bulkhead
42 extends vertically beneath the interior floor 32 and has a peripheral seal
44
which sealingly engages the raised portions 38, 40 of the bottom wall 30 and
the interior floor 32.
The refrigeration unit is comprised of an evaporator assembly generally
indicated by numeral 46 and a condenser assembly generally indicated by
numeral 48. The evaporator assembly 46 is mounted to one side of the
bulkhead 42 so as to extend rearwardly towards the back wall 24 inside the
insulated space defined between the interior floor 32 and the bottom wall 30.
The condenser assembly 48 is mounted on an inverted tray 50 (Figs. 5, 7)
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which also supports the bulkhead 42 at one end and which extends forwardly
of the bulkhead towards the front of the cabinet 20. The tray 50 is reinforced
by a pair of structural rails 51 (Fig. 4) which run the length of the side
walls
26, 28. The condenser assembly 48 is thus accommodated beneath the
forward portion of the interior floor 32. A cosmetically-pleasing, removable
grill 52 is disposed beneath the door 34 and conceals the condenser assembly
48 from view.
The evaporator assembly 46 comprises a motor 54 mounted to the
bulkhead 42 and operatively connected to drive a fan 56 disposed behind an
evaporator coil 58 as is conventional in the art (Fig. 2). The condenser
assembly 48 comprises a compressor 60, a motor 62 operatively connected to
drive a fan 64 and a heat exchanging condenser 66 (drawn in this order from
left to right in Fig. 2).
Coolant is circulated in a closed circuit between the evaporator assembly
46 and the condenser assembly 48, leaving the evaporator coil 58 as a gas for
compression in the compressor 60. The coolant is fed from the compressor
in a serpentine path through coil 68 supported inside a condensate tray 70
nested inside the inverted support tray 50 (Fig. 5). The coil 68 supplies the
heat exchanging condenser 66 where the coolant is ultimately condensed to
a liquid and returned to the evaporator assembly 46.
The interior floor 32 is spaced from the back wall 24 and an inner back
panel 72 extends along the height of the interior of the cabinet from the
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interior floor 32 towards the top wall 22. The space between the inner back
panel 72 and the back wall 24 is approximately 6 inches wide and vertically
divided by upright partitions 74, 76 (Figs. 2, 4). The left hand partition 74
is spaced from the left side wall 28 approximately 25% of the distance
separating the left side wall 28 from the right side wall 26 whereas the right
side partition 76 is spaced inwardly from the right side wall 26 by the same
distance of approximately 25% of the distance separating the right and left
side walls. Thus a central cold air passage 78 having a width of approximately
50% of the distance separating the left and right side walls 26, 28 is defined
between the left and right side partitions 74, 76. The evaporator assembly 46
is disposed inside the cabinet 20 so that cool air emerging from the
evaporator
coil 58 will enter the central cold air passage 78 for cold air flow.
An upper segment 74a of the left partition 74 is disposed at a 45°
angle to
join the left side wall 28 while an upper segment 76a of the right side
partition 76 is disposed at 45° to join the right side wall 26. Thus
the cold
air passage 78 covers the entire width of the insulated cabinet 20 at the top
of the cabinet to provide an equalized flow of cold air over the inner back
panel 72 which is spaced downwardly from the top wall 22 to define a cold
air outlet opening 80 (Fig. 4). The cold air outlet opening 80 extends across
the width of the panel adjacent to the top wall 22 and has a height of
approximately ll~z" to allow cold air to emerge from the cold air passage 78
into the refrigerated interior area of the cabinet 20.
The cold air outlet into the cabinet 20 defined by the opening 80 is
supplemented by a set of supplemental openings 82 formed in the inner back
panel 72 between the left and right partitions 74, 76 about midway along the
height of the inner back panel. In the embodiment illustrated in Fig. 4, a set
of nine supplemental openings are provided in a 3 x 3 array, each opening
having a width of approximately 3" and a height of 5/s". A louvred grill 83
covers the supplemental openings 82 and defines respective downwardly
curved air directors 84 (Fig. 1) disposed inside the cold air passage 78 and
extending partly between the inner back panel 72 and the back wall 24.
Left and right side return air passages 86, 88 are defined between the left
side partition 74 and the left side wall 28, and the right side partition 76
and
the right side wall 26 (as drawn in Fig. 2), respectively. Return air passage
86
is closed at the top by left partition segment 74a and return air passage 88
is
closed at the top by right side partition segment 76a. It will be understood
that the return air passages 86, 88 are in open communication at the bottom
thereof with the insulated compartment for containing the evaporator
assembly 46. Respective return air openings 90, 92 are provided in the inner
back panel 72 so as to be in fluid communication with the return air passages
86, 88. The return air openings in this embodiment are positioned in the
centre of the associated warm air passages and are spaced approximately 1"
above the interior floor 32 so as to extend upwardly approximately 10" with
a width of about 3". The return air openings 90, 92 are covered with
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respective wire grills 94, 96 adapted to allow an unrestricted flow of air
from
the refrigerated interior of the cabinet 20 into the return air passages 86,
88.
In use, cool air emerging from the evaporator assembly as indicated by
arrows 98 shown in broken outline (Fig. 1) is forced into the central cold air
passage 78 and is partially scooped by the air directors 84 for discharge
through the supplemental openings 82 into the refrigerated portion of the
cabinet 20 as indicated by arrows 100. A significant portion of the cool air
flow indicated by arrow 102 shown in broken outline is forced over the
upper portion of the inner back panel 72 and discharged through the top
opening 80 as indicated by arrows 104. There is sufficient pressure in the
emerging cool air 104 for at least some of this air to reach the front of the
cabinet adjacent the door 34, as indicated by arrow 106, while some of the air
descends into the cabinet under the influence of gravity. The return air flow
as indicated by arrow 108 is directed towards the inner back panel 72 above
the interior floor 32 where it enters the return air passages 86, 88 through
the
openings 90, 92 and is aspired by the evaporator fan 56 as indicated by arrows
110, 112, in Fig. 2 into the insulated compartment containing the evaporator
assembly 46.
Thus a circulatory air flow is created with cool air rising centrally along
the back wall, being discharged forwardly into the refrigerated portion of the
cabinet and returned on the interior floor of the cabinet to either side of
the
central cold air passage where it is returned to the evaporator assembly 46 so
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as to repeat the cycle. The supplemental openings 82 deliver cool air directly
to the bottom rear zone of the refrigerated cabinet interior and afford better
temperature control in that area.
Experimental tests conducted on a model of the merchandising cabinet
made according to the invention produced results graphically shown in Fig.
8 of the accompanying drawings. The tests were conducted on a cabinet
having six shelves carrying closely-packed soft drink cans occupying every
shelf inside the cabinet. Appropriate thermocouples placed in selected cans
on each shelf had their measurements recorded over a period of approximately
20 hours so as to record a temperature profile for each shelf similar to that
shown in Fig. 8. The graphical representation in Fig. 8 is an average of the
temperature profiles obtained for each of the six shelves and shows that it
took an average period of 13 hours for the soft drink cans to reach an
optimum temperature of 34°F from an ambient starting temperature of
76°F.
It will be appreciated that the evaporator assembly 46 is enclosed by an
insulated compartment defined by the insulated interior floor 32 above and
the bottom wall 30 below, the insulated bulkhead 42, the insulated back wall
24 and the side walls 26, 28. By virtue of its function, the evaporator coil
58
is very cold and inevitably any moisture carried by return air aspired through
the return air passages 86, 88 is condensed when it reaches the insulated
aforementioned compartment for the evaporator assembly 46. Effectively, the
evaporator coil 50 operates to dehumidify the air in the refrigerated portion
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of the merchandising cooler.
The bottom wall 30 is lined with a vacuum formed plastic evaporator pan
120 (Fig. 7~. The pan 120 is shaped to define a well 122 which, in use, is
disposed beneath the evaporator assembly 46 so as to collect any condensed
moisture dripping from the evaporator coil 58. The evaporator pan 120 is
conveniently shaped with a pair of detents 124, 126 each disposed on opposite
sides of the central air passage defined by left side partition 74 and right
side
partition 76. The detents are shaped to cooperate with respective inverted
channels 128, 130 riveted to a casing for the evaporator coil 58 on opposite
sides thereof and adapted to align with the detents 124, 126 so that the
evaporator coil 58 will be positioned in the central air passage 78.
At the bottom of the well 122, adjacent the raised portion 38 of the
bottom wall 30, a drain hole 132 formed into the evaporator pan 120 receives
a drain pipe 134 (Fig. 3~. The drain pipe 134 traverses the raised partition
38
of the insulated bottom wall 30 and extends beneath the bulkhead 42 where
it penetrates the inverted tray 50 and the condensate tray 70. A clip 135
retains the drain pipe 134 against the raised partition 38. Any liquid
collected
in the well 122 is thus discharged into the condensate tray 70.
The inverted tray 50 has an opening 136 to accommodate the condensate
tray 70 and which exposes the serpentine coil 68 emerging from the condenser
60. The condensate tray 70 is secured to the underside of the inverted tray
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50 at a peripheral flange 71 with fasteners 73 which may be released to
remove the tray 70. Condensed moisture emerging from the evaporator
assembly 46 and fed through the drain pipe 134 thus collects in the
condensate tray 70 to define a pre-cooling stage so as to assist in cooling
gaseous coolant in the serpentine coil 68 emerging from the compressor 60
prior to entry into the heat exchanging condenser 66. Conversely, hot
coolant flowing through the condenser coil 68 will assist in evaporating any
condensed moisture collected in the condensate tray 70, including any liquids
and condensed water vapor drained from the refrigerated interior of the
cabinet. Passage 138 formed in the insulated interior floor 32 (Fig. 1) and
cooperatively associated with a discharge tube 140, has its discharge end
disposed in the condensate tray 70 for drainage. Evaporation of the liquids
collected in the condensate tray 70 is further assisted by an ambient air flow
indicated by arrows 139 as air is aspired by the fan 64 through the grill 52,
adjacent the right side wall 26, and over the heat exchanging condenser 66 to
exit from the condenser assembly 48 through the grill 52 adjacent the left
side
wall 28 as indicated by arrows 141.
It will be appreciated that there is significant vibration between the
component parts of the condenser assembly 48, particularly as a result of the
operation of the compressor 60. In order to obviate any undesirable relative
motion between the condenser coil 68 and the associated condensate tray 70
whereby the coil could be damaged and coolant might leak, the condensate
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tray 70 is vacuum formed with a series of projecting risers 142 of which four
are shown in the embodiment illustrated in Fig. 7. The risers 142 have a
substantially truncated conical shape, each supporting a bracket 144 fixed to
the truncated top of each associated riser 142 by a suitable fastener such as
bolt 146 and nut 147 secured to the underside of the condensate tray 70.
Each bracket 144 has a pair of oppositely-directed arms 148 each having an
upwardly concave termination 150 adapted to cradle and support a loop of
the condenser coil 68. The arms 148 are dimensioned so that the terminations
150 are spaced from the underlying condensate tray 70 thereby minimizing
the adverse consequences of vibration resulting from the compressor 60.
Conveniently, the risers 142 space the fasteners from the bottom of the
condensate tray and thus minimize the occurrence of condensate leaks
through the tray.
The aforementioned arrangement of the condensate tray 70 also permits
the fastener 73 (Fig. 3) to be released from the inverted tray 50 so that the
condensate tray 70 can be removed for cleaning or replacing, as the case may
be, without removal of the heat exchanger 66 and disassembly of the
condenser coil 68. Thus, the arrangement not only prolongs the useful life
of the coil 68, it permits the assembly to be accessed for maintenance in a
very simple and easy fashion.
It will be understood that several variations may be made to the above-
described embodiment of the invention. In particular, it will be understood
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that the nature of the refrigeration assembly as defined by the evaporator
assembly 46 and the condenser assembly 48 may vary considerably. The
relative proportions of the central cold air passage and the return air
passages
may vary, as well as the location of the cold air outlets and return air
outlets
provided in the inner back panel 72 in accordance with the particular
application for which the cabinet is being used. The height of the return air
openings 90, 92 above the interior floor 32 could, for example, be raised to
create a slightly warmer environment in the cabinet for the storage of produce
such as cut flowers. Other variations within the scope of the appended claims
may be apparent to those skilled in the art, the structure defined for cold
air
passages and warm air passages being inherently flexible to create a cooling
environment adapted for any selected application.
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