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Патент USA US3029614

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April 17, 1962
E. c. ARMENTROUT
3,029,610
REFRIGERATING APPARATUS INCLUDING DEFROSTING MEANS
Filed July 25. 1960
IVA-IA
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5 Sheets-Sheet 1
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Everett 6‘. Arman/rout
BY
His Attorney
April 17, 1962
E. c. ARMENTROUT
3,029,610
REFRIGERATING APPARATUS INCLUDING DEFROSTING MEANS
Filed July 25. 1960
5 Sheets-Sheet 2
'
ig. 3
INVENTOR.
Evere? 6‘. Aren/rouf
BY
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H119 A/famey
April 17, 1962
E. c. ARMENTROUT
3,029,610
REFRIGERATING APPARATUS INCLUDING DEFROSTING MEANS
Filed July 25. 1960
5 Sheets-Sheet 3
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INVENTOR.
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Evere/r 0. Arman/rout
His' Af/omey
April 17, 1962
E. c. ARMENTROUT
3,029,610
REFRIGERATING APPARATUS INCLUDING DEFROSTING-MEANS
Filed July 25. 1960
5 Sheets-Sheet 4
INVENTOR.‘
EVere/f 6‘. Armentrauf
His Afro/‘hey
April 17, 1962
E. c. ARMENTROUT
3,029,610
REFRIGERATING APPARATUS INCLUDING DEFROSTING MEANS
Filed July 25. ‘1960
s Sheets-Sheet 5
~
INVENTOR.
EVere/l 6‘. A/jmenfmuf
BY
'
His A/Iamey
United States Fatent
‘lee
_
3,t2§,6ltl
Patented Apr. 17, 1952
3
3,029,610
REFRIGERATING _ FPARATUS INCLUDlNG
DEFRUSTING WAN?)
Everett C. Armentrout, New (Jarlisle, Ohio, assignor to
General Motors Corporation, Detroit, Mich, a cor
poration of Delaware
Filed July 25, 1960, Ser. No. 45,178
9 Glaims. (Ci. 62-156)
' This invention pertains to refrigerating apparatus and
more particularly to means for defrosting refrigerator
evaporators.
Hundreds of different arrangements have been devised
for defrosting refrigerant evaporators. There is no agree
tacle to cause the timing relay to stop the energization
of the defrost heater and restore the energization of the
motor-compressor unit and the below freezing compart
ment fan. To guard against prolonged heating of the
defrost heater, there is provided a safety switch in direct
heat transfer relation with the drain pan so that, upon an
abnormal rise in temperature of the drain pan, the system
will be restored to normal refrigeration operation. The
safety switch is arranged so that it must be manually op~
erated before any further automatic defrosting takes place.
Further objects and advantages of the present inven
tion will be apparent from the following description, ref
erence being had to the accompanying drawings wherein
preferred embodiments of the present invention are clearly
ment on which is the best. Clock-controlled defrosters 15 shown.
have been most popular. However,’ they are subject to
In the drawings:
mechanical breakage, wear and contact dif?culties. The
clock mechanism becomes noisy before the refrigerator
becomes obsolescent.
.
It is an object of this invention to provide a simple,
FIGURE 1 is a side vertical sectional view of a house
hold refrigerator embodying one form of my invention;
FIGURE 2 is a top view of a portion of the drain pan
for the below freezing evaporator shown in FIGURE
1 illustrating the location of the principal control ele
for periodically defrosting a refrigerant evaporator. .
ments of the defrosting apparatus;
It is another object of this invention to provide an im
FIGURE 3 is a fragmentary sectional view taken along
proved defrosting system in which a predetermined change
the line 3-3 of FIGURE 2;
in the state of a material periodically initiates a defrost 25 FIGURE 4 is a fragmentary sectional view taken along
ing period ‘together with improved means for restoring
the line 4-—4 of FIGURE 2;
the system at the end of the defrosting cycle.
FIGURE 5 is a sectional view through a bimetal timing
It is another object of this invention to provide a de
relay located adjacent the vegetable container in FIG
frosting system in which the complete congealing of a
URE 1;
liquid initiates a defrosting period and also the energize
FIGURE 6 is a vertical sectional View through a safety
tion of an electric heater in heat transfer with the con
switch associated with and located beneath the drain pan
inexpensive, quiet, reliable system without a gear train
gealed liquid to liquefy the congealed liquid for the
of the below freezing evaporator;
starting of a new refrigerating cycle.
FIGURE 7 is a top view of the closed receptacle con
These and other objects are attained in the forms shown
stituting the principal control element of the defrosting
35
in the drawings in which a household refrigerator having
system;
an upper, below freezing compartment is provided with an
FIGURE 8 is a side view of the closed receptacle;
evaporator beneath its false bottom wall and a lower,
FIGURE 9 is a bottom view of-the closed receptacle;
above freezing compartment is provided with a second
FIGURE 10 is a top view of the spider-type holder for "
evaporator behind a false rear wall. Separate fans circu
the closed receptacle and the bottom control switch and
late the air between each of these compartments and the 40 heater as well as the contact mechanism with the con
compartment behind the false walls containing the evapor
doctors on the closed receptacle;
ators. With such an arrangement, the frost only accumu
FIGURE 11 is a wiring diagram for the system shown
lates on the evaporators and does not accumulate in either
in FIGURES 1-10;
of the compartments. The evaporator adjacent the above
FIGURE 12 is a vertical sectional view through the
freezing compartment ordinarily defrosts every refrigera 45 bottom of a modi?ed principal control element; and
tion cycle. However, the frost accumulates on the below
FIGURE 13 is a simpli?ed wiring diagram for the sys
freezing evaporator.
_
tem including the control element shown in FIGURE 11.
According to my invention, in the wall between the two
Referring now to the drawings, there is shown an in
compartments, there is provided a closed glass receptacle
sulated refrigerator cabinet 20 having an upper, below
containing a small amount of water. The upper face of
freezing compartment 22 and a lower, above freezing
this receptacle is in contact with the bottom of the drain
compartment 24, each provided with insulated doors 26
pan.’ A small heater continuously heats the bottom of
and 28. The bottom of the below freezing compartment
the receptacle so as to slowly cause the water in the re
22 is provided with a false bottom wall 30 resting upon
ceptacle to accumulate and congeal on its upper face by
the tops of the ?ns of a vertically-?nned evaporator 34
the freezing action of the low temperature of the bottom
located between the false bottom wall 30 and a horizontal
of the drain pan. When all of this water has frozen upon
insulated wall 36. An evaporator compartment 38 is
the'upper face‘ of the receptacle, the bottom of the recep
formed ‘between the false bottom wall 30 and the insu
tacle rises in temperature and actuates'a bimetal switch
lated wall 36 Within which is located the evaporator 34.
which energizes either through a bimetal relay circuit or
The false bottom wall 3t} is provided with an entrance’ 40
directly a bimetal timing relay which stops the energiza
to this evaporator compartment 38 between it and the
tion of the compressor motor and the freeze fan motor
door 26. At the rear, there is connected an upwardly
extending duct 42 connecting with the inlet of the fan
and energizes a defrost heater associated with the below
44- dn'ven by an electric motor 46. The fan 44 dis
freezing compartment temperature. Also energized at
charges the air upwardly through the duct 48 into the
this time ‘is a small heater on the upper face of the re
ceptacle to melt the frozen water and a second small 65 top rear of the compartment 22 from which it flows di
agonally downwardly and forwardly to the entrance 40
heater associated with the bottom of the receptacle so as
to hold this bottom receptacle switch closeduntil the
below ‘freezing evaporator has been defrosted.
The temperature rise accompanying the defrosting of 70
the evaporator opens a bimetal switch thereon to deener
gize the holding heater at the bottom of the closed recep
of the evaporator compartment 38. The evaporator ‘34
is kept at a low temperature and thereon accumulates
any frost which may form. Since this evaporator is
isolated from the compartment 22, no frost will form in
the compartment.
The lower compartment 24 is provided with a false
3,029,610
3
applied.
As shown in the wiring diagram, FIGURE 11, the
base heater 92 is continuously connected between the
supply conductors L1 and L2. This is suf?cient to very
slowly vaporize the twenty~eight grams of water in the
discharges the air upwardly on both sides of the plate
evaporator 62 located in the evaporator compartment
glass receptacle 72. This takes abouttwenty-four hours.
This vwater freezes upon the upper face 78 of the closed
52. This cools the air drawn from the compartment 24
and discharges the cold air through the outlet 64 into the
upper portion of the compartment where it falls down
wardly to the bottom of the compartment. In the bottom
receptacle 72 Which is kept at freezing temperatures by
the evaporator'34 which is in direct contact with the plate
76 which rests ontop of the receptacle 72. The timing
relay 151 is locatedlin a wall of the above freezing com
of this compartment are one or two closed vegetable con
tainers 65 for keeping vegetables fresh and moist and
cold for good preservation. The refrigerating system in
cludes a compressor motor 66 which operates a conven
tional compressor, not shown, which in turn is opera
tively connected to a condenser for ?ow through a re
strictor to the ?rst evaporator 34 and the second evapo
rator 62 in series. The thermostat 68 is connected in
series with the compressor motor 66 and the fan motor
46. It is set to operate on a defrosting cycle and opens
the circuit to these motors when the evaporator 62 reaches
a temperature of 2° F. and closes the circuit to these
motors when the evaporator 62 reaches a temperature
4
grams of Water to which the reference character 149 is
rear Wall 50 behind which is an evaporator compartment
52 located in front of the insulated rear wall 54. This
evaporator compartment 52 has a lower entrance 56
forming the inlet to the fan 58 driven by an electric motor
60 located in a recess in the rear wall 54. This fan 58
15
partment 24 adjacent the vegetable containers 65. When
all of the water 149 in the closed receptacle 72 has been
evaporated from the base portion by the heater 92 and
frozen onto the top surface 78, the temperature of its
base 90 will rise due to the continued heating and di
minished cooling causing the heating of the thermostat
137 until it reaches its closing point of 160°. This closes
the circuit through the conductor 139 and the heater 141
to cause the timing relay bimetal switch member 143
to move out of contact with the contact 145 and into
contact with the contact 153. This contact 153 is con
nected through the conductor 155 and a bimetal switch
of 36° F., thus insuring the defrosting every cycle of the 25 157, called a safety switch, which is normally in contact
with the contact 159 connecting with the conductor 131
evaporator 62. However, the evaporator 34 remains
at a low temperature of about 0° '13‘. during both the run
and the cap heater 80 as well as the defrost heater 70
ning and off cycles. This causes the evaporator 34 to
gradually accumulate frost on its surfaces, thereby re
ducing its effectiveness and also obstructing the ?ow of
in parallel circuit. The contact 159 also connects through
a normally closed switch 161 of the thermostatic type
air through the evaporator compartment.
holding heater 163 located directly beneath the thermo
stat switch 137. The thermostatic switch 161 is cali
To remove this frost, the evaporator periodically is
defrosted by the application of heat by the defrost heater
70. According to my invention, this is controlled by a
comically-shaped sealed glass receptacle 72 containing
twenty-eight grams of distilled water.
This receptacle
72 is located in a comically-shaped well 74 in the insula
tion 36 and has its upper face in contact with a removable
plate 76 forming part of the drain pan 77 beneath the
evaporator 34. Preferably, the glass receptacle 72 is
made of borosilicate glass. On its wide top surface 78,
it is provided with a 10 watt, 1580 ohm strip heater 8%
which is connected by a conductor 162 in series with a
brated to close at 55° F. and to remain closed as long
as its temperature remains below 55° F. This thermo
35 static switch 161 is sealed in glass and is constructed
generally in the same manner as the switch 137. It is
fastened by a clip to one of the bends of the refrigerant
tubing extending froni'the evaporator 34 as shown in
FIGURE 1. This heater 163 is therefore energized dur
ing the defrost period along with the heater 8!} and the
defrost heater 70.
The defrost heater 70 heats the evaporator 34 and the
frost collected thereon so that the frost ?ows ‘off the
formed by an extremely thin ?lm of zinc oxide bonded to
evaporator 34 in the form of water onto the drain pan
the surface of the glass. One of the ends of each of these
strips are electrically connected by a silver metal strip 82 45 77. This water ?ows from the drain pan 77 through
the outlet 165, through the insulating wall 36 into a
formed by spraying the silver metal onto the glass sur
de?ector 167 in the above freezing compartment 24
face. The opposite ends are connected by similar silver "
and ?ows down the back wall of the evaporator com
strips 84 and 86 similarly formed by spray metal.
partment 52 to a drain 169 leading to a water disposal
The strip 86 continues on down to the base 90 having
a base heater 92 formed of four strips joined in series 50 device located in the machinery compartment. The
heater 163 applies heat to the switch'137 during the de
in the form of thin ?lms of zinc oxide bonded directly
frost‘ cycle to prevent the timing relay 151 from prema
to the surface of the glass. This bottom or base heater
hase a value of 4840 ohms and 2.9 watts. It has one
terminal connected to the strip 86 and a second terminal
turely returning to the refrigeration position. The cap
three oval-shaped terminal portions 125, 127 and 129
forming a continuation of the sprayed metal strips 94,
ing is still required during the defrost period. The de
heater 8t} heats the upper surface 78 of the receptacle
connected by a silver metal spray strip 94. The sealed 55 72 to assure that the ice congealed thereon is melted dur
receptacle 72 is supported and held in place against the
ing the defrost cycle and returns to the base 90 to again
bottom of the plate 76 by a four-armed plus-shaped
form the pool of liquid 149 therein to prepare for the
spider 96 which fastens to the plate 76 at the ends of its
start of the new cycle. '
four arms. This spider supports three spring contact
The heater 163 prevents the cooling effect of this re
members 98, 121 and 123 which are held in contact with 60 turn water 149 from opening the switch 137 while defrost
frost heater 70 continues in operation to heat the evap
86 and 84 respectively. These contact members 98, 121
orator 34 and defrost the frost thereon until the switch
and 123 connect to the conductors 131, 133 and 135. The
161 on the evaporator 34 reaches the temperature of 55°
spider 96 also supports a thermostatic switch 137 sealed 65 and opens. This deenergizes the heater 163 allowing
in glass and held against the base of the receptacle 72.
the switch 137 to be cooled by the liquid in the receptacle
The thermostat 137 is connected by the conductor 139
72 causing the switch 137 to cool and open and deener
gize the heater 141, thus allowing the bimetal switch
to the electric heater 141 of a ‘bimetal timing relay 151
143 to move away from the contact 153 and back into
\which includes the bimetal element 143 which is of the
double throw type and normally connects through the 70 contact 145 to resume the normal refrigeration cycling
under the control of the thermostat v68. The timing
contact 145, the conductor 147 and the thermostatic
relay 151 is placed in the above freezing compartment and
switch 68 with the compressor motor 66 and the ‘fan
has a perforated wall 142 permitting air circulation so
motor 46. The heater 141 is of a special glass having a
that it will cool rapidly and rapidly move back to the
composition making it a high resistance electrical heater.
The glass receptacle 72 is charged with twenty-eight 75 refrigerating position quickly after the heater 141 is
3,029,610
de‘energized.’ The fan 58 by inducing circulation aids in
cooling the timing relay 151. The motor 60 of the fan
58 is controlled by a thermostat 171 connected in series
with it and located adjacent the entrance '56 to the fan 58.
The safety switch 157 includes a housing 173 clamped
directly‘to the bottom of the drain pan ‘77 as shown in
FIGURES 9 and 2. It includes an L-shaped structural
member 175 fastened to the base 177. This L-shaped
member has fastened to it a hook-shaped actuating bi
6
the switch 221 is connected by a conductor 251 to the
terminal 253 connecting with the double throw switch
member 255 of the safety switch 241. The third ter
minal 257 of the safety switch 241 is connected by the
conductor 259 to the upper or top heater 261 of the
receptacle 72 and in turn is connected to the supply
conductor L1. The defrost heater 263 is connected di
rectly in parallel with the heater 261 between the terminal
257 and the supply conductor L1. When the heater 261
metal member 179 acting through the toggle blade 181 10 returns a su?icient amount of ice as water to the base of
to operate the double throw contact member 183 having
the receptacle 72, the bimetal 223 is cooled sufficiently in
its one end anchored to the L-shaped member 177 as
spite of the heater 229 to return to its normal refrigera
shown. The housing 173 conducts heat and cold between
tion position shown in FIGURE 12 to terminate the de
the drain pan 77 and the members 177, 179. When
frost cycle. The safety switch 241 acts like the safety
‘the. member 179 reaches a temperature of about 90° 15 switch 157.
F., ‘it will bow upwardly far enough to cause the toggle
‘If desired, the below freezing compartment may be lo
spring 181 to trip the contact member 183 from its
cated below the above freezing compartment with the
upper position to its lower position in contact with the
evaporator for the below freezing compartment and the
stationary contact 185. This deenergizcs the defrost
receptacle and the safety switch being loctaed in the wall
heater 70 and prevents overheating of the evaporator ~34 20 between the below freezing compartment and the ma
and its compartment 38 and surrounding parts in the
chinery compartment.
event that the control'system fails to function for any
While the embodiments of the present invention "as
cause whatsoever. The control 157 is provided with a
herein disclosed, constitute preferred forms, it is to be un
shoulder 187 which stops the bimetal arm 179 in its
derstood that other forms might be adopted.
downward movement so that it is incapable of returning 25
What is claimed is a follows:
the contact member 183 to its normal upper position.
1. A refrigerating system including refrigerant liquefy
This insures that, after a defrost cycle which causes
ing and evaporating means operatively connected, a closed
overheating of an evaporator, the defrost system will not
receptacle having a ?rst portion in heat transfer relation
again repeat without the owner being aware of it. The
ship with said evaporating means and having a second
safety switch 157 in this safety, position insures resump 30 portion, means for heating said second portion, said
tion 'of refrigeration under'the control of the switch 68.
receptacle containing a liquid movable by the differential
If the switch 157 trips to the safety position, to return
in temperature of said ?rst and second portions from
to the automatic defrosting, it must be reset by the re
said second portion to said ?rst portion, means for de
turn push but-ton 189 which is slidably mounted in the
frosting said evaporating means comprising control means
base ‘157 and normally is separated from the‘ blade 183. 35 operable in response to the movement of said liquid from
An upward push of the push button 189 moves the blade
said second portion to said ?rst portion, and a second
183 away from the contact 185 and back into contact
heating means in direct heat transfer relation with said
with the contact 159 ‘to make possible continued auto
?rst portion and responsive to the operation of said ‘con;
matic defrosting.
trol means for moving said liquid from said ?rst portion
In the form shown in FIGURES l2 and 13, a sim
back to said second portion.
pli?cation is accomplished by consolidating the thermo
static switch 137, the holding heater 163 and the timing
2. A refrigerating system including refrigerant liquefy
ing and evaporating means operatively connected, a closed
relay 151 into a single double throw bimetal switch 221
receptacle having a ?rst portion in heat transfer relation
mounted directly at the base of the closed receptacle.
ship with said evaporating means and having a second
The closed receptacle 72 remains the same with the top 45 portion, a ?rst heater integral with the wall of said second
or cap heater 80 on the top 76 and the base heater 92
portion, said receptacle containing a liquid movable by
at the base 90. However, directly mounted to the base
the differential in temperature of said ?rst and second
95) is a'double throw bimetal switch, generally designated
portions from said second portion to said ?rst portion,
by the reference character 221, having a bimetal actuating
a second heater integral with the wall of said ?rst portion,
tongue ‘223 connected through a C-shaped toggle spring
and control means operable in response 'to the movement
22-5 to a double throw spring blade 227 carrying a double
of said liquid from said second portion to said ?rst por
throw contact. The base heater 229 is decreased in re
tion for energizing said second heater‘ and ‘for controlling
sistance and increased in wattage so that, whenever all
said liquefying means.
the water within the receptacle 72 is evaporated from the
3. A refrigerating system including refrigerant liquefy
base thereof and frozen onto the upper surface, the bi 55 ing and evaporating means operatively connected, a closed
metal 223 will" be heatedsu?iciently to cause it to move
receptacle having a ?rst portion in ‘heat transfer relation-‘
downwardly and trip the ‘spring blade 227 to the upper
ship with said evaporating means and having a second
position in contact with the contact 249 and to hold it
portion, means for heating said second portion, said re
there for the duration of the defrost cycle. This bimetal
ceptacle containing a liquid movable by the differential
223 operates the blade 227 to this upper position when 60 in temperature of said ?rst and second portions from
it reaches a temperature of about 125° to initiate the de
said second portion to said ?rst portion, a thermostatic
frost cycle. In this form, the charge of distilled water
switch associated in heat transfer relation with said sec
149 for the receptacle 72 is increased to thirty grams to
ond portion and operable from one position to another in
compensate for the increased wattage of the base heater
response to an increase in temperature resulting from
229.
65 the movement of saidliquid from said second portion to
The terminal 231 has one connection to the supply con
said ?rst portion, and a relay controlled by said thermo
ductor L2 and arconductor 233 connecting with the base
static switch for changing the operation of said liquefying
heater 229 which in turn is connected to the second
means to provide a defrosting cycle.
supply conductor L1. The terminal 235 is connected by
4. A refrigerating system including refrigerant liquefy
the conductor 237 to the terminal ‘239 of the safety 70 ing and evaporating means operatively connected, a closed
switch 241 which is identical to the safety switch 157.
receptacle having a ?rst portion in heat transfer rela
This terminal 239 is connected through the thermostat
tionship with said evaporating means and having a sec
switch 243 and the compressor motor 245 to the supply
end portion, means for heating said second portion, said
conductor L1.
The terminal 239 also connects to one
receptacle containing a liquid movable by the differential
contact 247 of the safety switch. The terminal 249 of 75 in temperature of said ?rst and second portions from
3,029,610
7
8
ond compartment and said ?rst portion of said receptacle,
said receptacle being arranged for ‘gravity ?ow from said
said second portion to said ?rst portion, a thermostatic
switch associated in heat transfer relation with said
second portion and operable from one position to an
?rst portion to said second portion and containing a con
gealable liquid normally collecting by gravity in said
other in response to an increase in temperature resulting
from the movement of said liquid from said second por
tion to said ?rst portion, a second heating means in in
timate heat transfer relation with said ?rst portion of
lower second portion, liquefying means operably con
nected to said evaporator for normally maintaining said
evaporator below the congealing temperature of said con
gealable liquid, and means responsive to the congealing
said receptacle, and a relay controlled by said thermostatic
of a predetermined amount of said liquid upon said ?rst
switch for energizing said second heating means.
5. A refrigerating system including refrigerant lique 10 portion for controlling said liquefying means.
8. A refrigerating system including means forming an
fying and evaporating means operatively connected, a
evaporator compartment and a second compartment,
closed receptacle having a ?rst portion in heat transfer
means separating said evaporator compartment from said
relationship with said evaporating means and having a
second compartment, a closed receptacle having an upper
second portion, means for heating said second portion,
said receptacle containing a liquid movable by the dif 15 ?rst portion of its surface exposed in said evaporator
compartment and ‘a lower second portion of its surface
ferential in temperature of said ?rst and second portions
isolated from said evaporator compartment in said sepa
from said second portion to said ?rst portion, a thermo
rating means, said receptacle being arranged for gravity
static switch associated in heat transfer relation with said
?ow from said ?rst portion to said second portion con
second portion and operable from one position to an
other in response to an increase in temperature resulting 20 taining a liquid normally collecting by gravity in said
lower second portion, an evaporator in said evaporator
from the movement of said liquid from said second por
compartment for cooling said second compartment and
tion to said ?rst portion, a second heating means in heat
said ?rst portion of said receptacle, heating means associ
transfer relation with said thermostatic switch, and a
ated with said second portion and the liquid in said recep
relay controlled'by said thermostatic switch for energiz
25
tacle for causing said liquid to migrate from said second
portion to said ?rst portion, liquefying means operably
walls enclosing an upper below freezing com
and a lower above freezing compartment, an
wall separating said upper and lower compart
false bottom wall spaced above said insulated 30
connected to said evaporator, and control means for said
liquefying means responsive to a predetermined migra
tion of said liquid from said second portion to said ?rst
ing said second heater.
6. A refrigerating system including a cabinet having
insulated
partment
insulated
ments, a
wall providing an evaporator compartment in between,
a ?rst evaporator with said evaporator compartment and
a second evaporator located in heat transfer relation with
said lower compartment, means for circulating air from
portion of said receptacle.
9. A refrigerating system including refrigerant lique
fying and evaporating means operatively connected, a
closed receptacle having a ?rst portion in heat transfer
relationship with said evaporating means and having a
said below freezing compartment through said evaporator 35 second portion, a ?rst heater integral with the wall of said
second portion, said ‘receptacle having the second por
compartment in heat transfer with said ?rst evaporator
tion lower than the ?rst portion for gravity flow from said
and return, a closed receptacle having an upper ?rst por
?rst portion to said second portion and containing a
tion in heat transfer relation with said evaporator com
liquid movable by the differential in temperature of said
partment and a lower second portion lodged in said in
sulated wall, said receptacle having the second portion 40 ?rst and second portions from said second portion to said
?rst portion and movable by gravity from the ?rst por
lower than the ?rst portion for gravity ?ow from said ?rst
portion to said second portion and containing a limited
tion to the second portion, control means for said lique
quantity of water normally collecting by gravity in said
fying means operable in response to the movement of
lower second portion capable of freezing at temperatures
said liquid from said second portion to said ?rst portion,
normally prevailing in said evaporator compartment ad 45 means for normally controlling said liquefying means to
jacent said ?rst portion, and means for defrosting said
?rst evaporator comprising control means associated with
said receptacle and responsive to the freezing of said
water.
maintain said evaporating means below the congealing
temperature of the liquid in said receptacle, said control
means comprising means for deenergizing said ?rst heater
and stopping said liquefying means to allow the return
7. A refrigerating system including means forming an 50
of said liquid in said receptacle to said second portion.
evaporator compartment and a second compartment,
means separating said evaporator compartment from said
References Cited in the file of this patent
second compartment, a closed receptacle having an upper
?rst portion of its surface exposed in said evaporator
UNITED STATES PATENTS
compartment and a lower second portion of its surface
Kurtz ___________ _‘__-__ Nov. 21, 1950
2,531,136
isolated from said evaporator compartment, an evapora
Pas _________________ __ June 14, 1960
2,940,277
tor in said evaporator compartment for cooling said sec
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