Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1 BACKGROUND OF THE INVENTION
Refrigerated display cases are widely employed for
effectively merchandising food products while maintaining
such in prime condition. Yet, because of the significant
energy usage requirements of such cases, particularly open
front display cases, there is a tendency to cut back on
usage thereof in recent times. Energy is required for
refrigeration of these cases, for antisweat heat during
refrigeration, and often for defrosting. Creative con-
`,~ 10 cepts have been put forth recently for decreasing energy
consumption o refrigeTated display cases. In U. S. Patent
4,026,121, issued May 31, 1977 to Yoshitaka Aokage et al.,
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a special reverse flow air defrost system is taught.
SUMMARY OF THE INVENTION
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`~-, 15 This invention relates to use of diverted anti-
sweat heat electrical energy in a refrigerated display case
.l during the defrost mode, and more particularly to diversion
of such electrical energy to evaporator defrost heaters.
Electrical controls that switch the refrigerated display
from refrigeration mode to defrost mode divert the elec-
trical energy normally used for antisweat heaters during the
refrigeration mode, to evaporator defrost heaters during
the defrost mode.
This development achieves significant energy
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1 conservation. There are two combinations capable of ex-
hibiting the energy conserving benefits, one being an open
-front refrigerated display case combining reverse -flow air
defrost with diversion electrical energy coil defrost, and
the other being a door-type display case with diversion
electrical energy coil compartment defrost.
The diversion of energy to defrost heat in an open
front display case employing reverse flow air defrost causes
accelerated defrost, thereby shortening the defrost time
period and enabling retention of low food product temp-
eratures. Defrost not only occurs more rapidly, but with
~- less wattage.
In the door-type, i.e. so-called reach-in re-
frigerated display case or cabinet employing diversion
electrical energy defrost, the heat is basically concen-
trated and confined to a coil chamber, to allow maintenance
of low product temperature as well as less energy consumption.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevational sectional view of an
open front refrigerated display case embodiment-of this
invention;
Fig. 2 is a schematic electrical diagram for the
embodiment in Fig. l;
Fig. 3 is a side elevational sectional view of a
door-type refrigerated display case embodiment of this
invention; and
Fig. 4 is a schematic electrical diagram for
the embadiment in Fig. 3.
DESCRIPTION OF THE PREFERRED E~BODIMENTS
OpEN FRONT E~BODIMENT
Referring specifically to Fig. 1, the open front
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1 multiple curtain refrigerated display case 10 constitutes a
housing assembly 12 having an access opening 14 over the
' front thereof, rom the ambient air space 16 about the
cabinet to the food storage and display space or zone 18 in
, 5 the cabinet. This structure is normally placed in a grocery
',, store or supermarket, with display space 18 being divided
into sections by a plurality of vertically spaced generally
horizontal shelves 20. Display space 18 is conined, by an
,` upper panel OT ceiling Z2, a rear panel or wall 24 to which
the shelves are attached, a bottom panel 26 which also
-' serves as a support shelf, and a pair of end walls 28.
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~xtending around and adjacent the bottom 26, back
," 24 and top 22 of display area or space 18 is an inner,
'~ refriger'ated air flow passage or conduit 30 extending , ,
. 15 substantially along the length of the case. Passage 30 has
an el'ongated upwardly oriented air flow inlet 32 extending
along the lower edge of access opening 14, and normally
covered by a perforate grill 34 which may be electrically
heated to prevent frost formation. Along the upper edge of
the access opening 14, opposite inlet 32, is an elongated
air flow outlet nozzIe 36 no~mally containing downwardly
oriented air directing means such as honeycomb as depicted.
This outlet nozzle is the innermost of a plurality of
outlets, preferably three in number. It discharges re-
frigerated air down across the open front of the display
space to the inlet 32 for recirculati~n about the case.
Located in passage 30, preferably along the lower
rear portion thereof, as in the space behind the downwardly
forwardly sloping back panel 24, is evaporator coil means 38
containing the' usual tubes and fins, and extending generally
along the length of the back panel such that air flow
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1 recirculating through the innermost passage of the display
must flow through the coil during normal operation. This
' evaporator refrigeration equipment is operably connected
to conventional condensing equipment external of the display
case in usual fashion, e.g. on the roof of the store, at
the rear of the store, or otherwise, as is normally done.
'' Also within passage 30, preferably at the bottom
portion of the display case, is a plurality of motor oper-
ated fans 4Q spaced lengthwise along the display case and
acting as air propelling means to constantly circulate air
' drawn into inlet 32, past these fans 40, through passage 30,including coils 38, out outlet 36, and down across the open
front 14 of the display case, i.e. in counterclockwise
fashion in the form depicted in Fig. 1 as represented by the
solid arrows. T~us, the refrigerated air is recirculated in
this fashi'on. Passage 30 is basically defined between the
noted panels 26, 24 and 22 forming one side thereof, and a
spaced panel' or partition 42 extending around the bottom,
back'and top of the case to form the other side of the
passage. The refrigerated air flowing through passage 30
not anly forms an enclosing air curtain in the open front of
the case, but also a protective envelope around the case.
Partition 42 not only forms the outer wall of
inner passage 30, but also forms the inner wall of a second
adjacent passage'44 which extends around the bottom, back
and top of the case outwardly of passage 30, relative to
,~ display space 18. The ou~er wall of passage 44 is formed by
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bottom panel' 46 and back and top panels 46' and 46".
Passage 44 includes an elongated inlet 48 adjacent to and
3Q outwardly of inlet 32, i.e. along the lower edge of the
display opening 14. Opposite this upwardly opening inlet 48
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1 and adjacent the outlet nozzle 36 at the top edge of the
display opening 14 is another downwardly oriented elongated
outlet nozzle 52 from passageway 44 including air directing
means such as honeycomb as depicted. During normal opera-
tion, air is circulated through passage 44 by a plurality of
motor operated fans 54 preferably in the bottom of the case.
These fans propel air from inlet 48 through passage 44,
enveloping the refrigerated air passage 30, and out nozzle
52~ to form a protective guard curtain of air contiguous
with and flowing in the same direction with the refrigerated
inner air curtain across the open front of the case. This
guard curtain returns to outlet 48 for continuous recircu-
lation, all as shown by the solid arrows in Fig. l. Typically
during normal operation, the temperature of this recir-
culated guard air through passage 44 is at a temperature
somewhat higher than the temperature of the inner refrig-
erated air curtain, but below ambient temperature. It is
cooled somewhat by its association with the inner air
curtain. Fans 54 are spaced longitudinally along the
passage to obtain relatively uniform flow over the length of
this passage.
A third curtain of air at ambient temperature is
preferably also employed. This curtain is not recirculated
about the case, but rather enters the case at the top and
exits in front of the rub rai] into the aisle. The ambient
air for this third curtain enters the case through a plur-
ality of top inlets 56 covered by perforate grids 58 or the
like, the air being drawn down in by a plurality of motor
operated fans 60 spaced longitudinally along the top of the
case length. The air is then propelled downwardly through
elongated passage 62 between panels 46" and top panel 64 to
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1 a third elongated outlet nozzle 66 along the top edge of the
case, and directed downwardly across the open front of the
case outwardly of the inner two nozzles relative to the
display space 18.
Nozzle 66 is adjacent nozzle 52 and preferably at
a small acute angle relative thereto, with nozzle 52 also
preferably being at a relatively small acute angle relative
to nozzle 36, all in Xnown fashion. The air flow normally
flowing through nozzle 66 is, as indicated by the solid
arrows, flowing across the open front or access opening
contiguous with the curtain from nozzle 52, and, at the
lower edge of the access opening, separating from the
intermediate air guard curtain and flowing out over the rub
rail into the aisle area of the store for customer comfort
as well as adding inertia to the total air curtain flowO
The motors 55 that operate the guard curtain fans
54 are electrically reversible, as are the fans therefor, to
enable air to be forced in the opposite direction for
passage 44 from that shown in the solid arrows, i.e. in the
direction indicated by the dashed arrows during defrost
operation. This reverse flow defrost concept is basically
set forth in U. S. Patent 4,026,121. Thus, during defrost,
: the air is drawn into the intermediate guard nozzle 52, both
from the outlet nozzle 66 and also from the ambient at-
mosphe~e in front of the case, is circulated around the
display9 and is discharged up through the opening 48.
During defrost9 air leaving opening 48 can be drawn down
into opening 32, assisted by deflector 49 at the end of
opening 48. The panel or wall 42 that separates the con-
duits 30 and 44 along the bottom of the display case has an
upwardly protruding terminal portion 42a between the open-
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: 1 ings 32 and 48.
The electrical circuit for the open front embodi-
ment is shown in Fig. 2 in relation to -four display cabinets
or cases. In this illustrative showing, the fourth case is
display cabinet 10 of the other drawings. The deErost
controls shown include a demand defrost control 150. That
is, defrost occurs when the sensor at the cabinet indicates
it needs defrost, as detected by a predetermined difference
in temperature between the inlet air to the coil and the
outlet air from the coil. The control is marketed by
Minneapolis Honeywell Co. as "Honeywell Demand Defrost
Control CR70A'1. Details are set forth in U. S. Patent No.
3,453,837. A sensor for the control may be placed in each
of the multiple of cabinets to cause any one of such to
trigger the defrost operation. In such an arrangement,
switches 154 and 156, and light 158 would be only on the
cabinet on which control 150 is mounted, while each cabinet
would hiave a control 152, switch 162 and light 160. Control
152 is marketed by Minneapolis Honeywell Co. as "Dew Point
Controller 4-409A11. This demand control may be substituted
by a conventional timer-operated defrost control if desired.
The control circuit also includes a control 152
that conserves energy by shutting down the antisweat heaters
168 on the cabinet during defrost, and diverting the power
for such to defrost heaters 166 upstream of the coil.
: Control 152 may be, for example, a 1'Honeywell Ant-i-Sweat
Control H-40~A". Also incorporated into the illustrated
circuit are end lock-out time delay manual switch 154,
manual defrost activation switch 156, indicator light 158
preferably red, indicator light 160 preferably yellow,
toggle switch 162, and double pole, double throw de:Erost
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1 relay 164. The antisweat heaters are connected to the
antisweat control 152. This control allows only the re-
quired amount of energy to be used by the antisweat heaters
to prevent condensation du~ing the refrigeration mode.
S Percent of energy used will vary from 100% at 65~ relative
humidity to 0~ at 20% relative humidity.
When the cabinet requires a defrost, control 150
will pu~ the cabinet into defrost automatically. The red
indicator light will come on, telling the store personnel
the slightly warmer temperature in the cabinet is due to the
defrost mode and no~ a malfunction of the refrigeration
system. When the cabinet goes into defrost, defrost relay
164 de-energizes all the antisweat~heaters 168 and energizes
defrost heaters 166 in front of the evaporator coil to work
in combination with the warm air propelled through the
passages and coil by reversal of the guard curtain. This
diversion of heat shortens the defrost period, protecting
the product from deteriorating. If it is desired to put the
- cabinet into a manually activated defrost, the two push
button switches i54 and 156 are depressed momentarily.
The combination of reverse flow defrost air and
heat from diversion energy is highly effective, yet con-
serving of energy. In this open front type of case, there
would not be sufficient energy from the diverted antisweat
requirements alone for defrost. Yet, with the warm ambient
air being complemented in this fashion, the results are
highly effec~ive.
DOOR-TYPE EMBODIMENT
In Fig. 3 is depicted a reach-in or door-type
refrigerated display case 110 employing a conventional
housing 1l2 ~hich has a top 11~, back 116, bottom 118, front
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1 120 and ends 122. The front includes a plurality of doors
lZ4, usually largely glass to allow viewing therethrough,
such doors being slidably or hingedly mounted in conven-
tional fashion for access to the interior product storage
and ~isplay space 126. The food products are supported on a
plurality of vertically spaced, generally horizontal shelves
128 mounted in cantilever fashion from the back of the
cabinet.
At the top of the cabinet is a space 130 separated
from the product storage and display space 126 by a ceiling
panel 132. ~ithin space 130 is mounted a refrigeration coil
134 positioned across the passage so that air propelled by a
plurality of motor operated fans 136 is forced through the
coil for cooling of recirculated air prior to its passage
about ~he cabinet. The air flo~s down the back of the
cabinet between a back panel 140 and the case back 116,
behind the products, through the space below bottom panel
144 and above case bottom 118, and then up in front of the
shelyed products, i.e. between the pToducts and front doors
124, such air returning through openings 132' in panel 132,
back to the fans 136, in recirculatory fashion. Adjacent
glass doors 124 are positioned conventional vertically
oriented fluorescent lamps 125 for illumination of the
display space. Re~rigeration coil 134 is in cooperative
relationship with a compressor and condensor unit ~not
shown~ located elsewhere through suitable conduits 135 in
normal fashion.
On the face of the doors is mounted antisweat
heaters which typically include door perimeter heaters 150
3Q (Fig. 4)~ glass door heaters 152, mullion heaters 154, and
case perimeter heater 156. Such heaters are typically
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1 resistance heaters, and serve to prevent condensation
forming on the noted surfaces.
In accordance with this invention, there is
located immediately adjacent coil 134, therebeneath, a
plurality of defrost heater elements 160 ~Figs. 3 and 4)
operated alternately with the noted antisweat heaters.
Temperature control 164, pressure control switch 166 and a
t~imer subassembly 168 govern these heaters as explained
hereinafter. The timer subassembly includes ~imer motor TM
which operates a normally closed timer swi~ch A and a
normally open timer switch B, and includes a solenoid 170.
A single pole double throw relay 174 has a coil I, and a
switch 176 normally closed at terminal H and normally open
at terminal J for alternately operating the antisweat
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heaters and the evaporator defrost heaters, respectively.
An evaporator defrost termination and fan delay control
subassembly 180 includes a switch 182 normally closed to
terminal C and normally open relative to terminal L. When
closed to terminal C, the switch completes a circuit to coil
2Q D in single pole double throw relay 184, the switch 186 of
which i5 normally closed to terminal E and normally open to
terminal F. Terminal E and the switch thus complete a
- circuit to the electrical motors G for the evaporator fans
136. For clarity, the operational sequence is as follows:
Refrigeration Mode
1. Timer switch "A" is closed.
2. Timer switch "B" is open.
3. Defrost termination switch is in contact "C"
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position.
4. ~elay coil IIDIt is energized, halding switch
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~; 186 in closed position at contact "E".
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1 5. ~vaporator fans run continuously until the
de-frost period.
6. Glass door and rame antisweat heaters are
energized through one side of relay 174, terminal "H", from
a separate 115 volt circuit as depicted.
DeErost Mode
1. Defrost timer switch "A" is open and "B" is
closed, being mechanically activated by the timer at a
preset time.
2. Opening of switch "A" de-energizes coil "D",
putting relay in "F" pasition stopping fan motors "~".
3. Closing of switch "B" energizes coil "I" in
relay 174.
4. Energizing coil "I" puts relay in "J" position
that energizes defrost heaters 160 and de-energizes anti-
sweat heaters 15Q, 152, 154, and 156. The heat given off by
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the defrost heaters is confined within the space 130 to
maximize defrost action with less energy consumption.
5. When the sensing bulb 190 of defrost term-
ination control reaches the preset temperature (usually
about 45 degrees F.~ the control switch takes the position
"L".
6~ This activates solenoid 170 which returns the
system to the refrigeration mode.
Resumption of Refrigeration Mode
1. Opening of switch "B" de-activates coil "I"
and returns switch of relay 176 to "H" position. This
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terminates the heat in the defrost heaters and re-energizes
the antisweat heaters.
2. When the sensing bulb of the defrost term-
~-~ inatian control reaches about ~20 degrees F. the switch
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1 returns to position "C".
3. This reactivates the coil "D" and the relay
switch returns to switch position "E" starting up the fans.
There is preferably an approximately ~hree minutes delay in
starting up of the fans after refrigeration is started to
allow proper lowering of the coil temperature before air
flow through it, to avoid raising of the temperature in the
product display and storage space.
In this door-type of display case, the energy
requirements for antisweat heat are quite high, causing the
diversion use thereof to be sufficient for defrost of the
coil with confinement of the heat to the small coil chamber
above the display space, with the fans no~ operating. The
melted frost and ice rom the coil flow into a trough 190
lS for flow out plpe 192 to drain.
Conceivably details of these two combination
embodiments could be altered within the concept presented,
the scope of the invention being set forth by the following
claims and the reasonable equivalents thereto.
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