US2717499A

US2717499A - Ice maker

Info

Publication number: US2717499A
Application number: US325186A
Authority: US
Inventors: Carl T Ashby; Benjamin A Phillips
Original assignee: Servel Inc
Current assignee: Servel Inc
Priority date: 1952-12-10
Filing date: 1952-12-10
Publication date: 1955-09-13
Anticipated expiration: 1972-09-13

Description

Sept 13, 1955 c. T. AsHBY ET AL v 2,717,499

ICE MAKER Filed Dec. lO, 1952 4 Sheets-Sheet l BY WM? TTORNEY Sept. 13, 1955 c. T. ASHBY ET AL ICE MAKER 4 Sheets-Sheet 2 Filed Deo. lO, 1952 imxlmm..

Sept- 13, 1955 c. T. ASHBY ET Al. 2,717,499

ICE MAKER Filed Deo. lO, 1952 4 Sheets-Sheet 4 ATTORNEY UnitedA States Patent O ICE MAKER Carl T. Ashby and Benjamin A. Phillips, Evansville, Ind.,

assigner to Servei, line., New York, N. Y., a corporation of Delaware Application December 10, 1952, Serial No. 325,186

8 Claims. (Cl. 62-6) This invention relates to automatic ice makers, and particularly a method of and means for preventing the accumulation of frost o-n an automatic ice maker.

More particularly, this invention relates to the prevention of the accumulation of frost in the freezing compartment of a refrigerator and on an automatic ice maker position therein.

A copending companion patent application of Harry C. Shagaloff, Serial No. 325,097, filed December 10, 1952, discloses and claims an automatic ice maker with which this invention has particular use.

Briefly, the above Shagaloff application discloses an automat-ic ice maker wherein an ice mold and an ejector mechanism are located within the low temperature or freezing compartment of a household refrigerator. The ice mold is divided into ice forming compartments, each having a generally arcuate contour so that the ejector mechanism, which is mounted above the mold, may rotate through the ice forming compartments of the mold and sweep the ice pieces therefrom. The ice removing action is automatic, as is the filling of the mold, freezing, and loosening of the ice pieces. The ice pieces are detained on the ejector mechanism for thorough drying before discharged to storage, The automatic operation is stopped short of discharge of ice to storage and remains suspended during the time that a desired quantity of ice is held in storage. Power for operating the ejector mechanism and the control mechanism therefor is provided by a geared electric motor. This motor is of the type that will stall while energized when the ejector mechanism contacts the ice frozen solidly in the mold without burning out or otherwise harming the motor. The electric motor and the measuring vessel for supplying a measured quantity of water to the ice mold are located on the rear exterior wall of the refrigerator.

lt has been found in practice that with an ice maker of the type disclosed in the above copending Shagaloff application, wherein the ice mold is located in the freezing compartment of the refrigerator, that the relatively warm water, supplied to the mold for freezing, causes water vapor to condense and collect on the ice maker and on the walls of the freezing compartment. This condensate freezes into frost or ice, and unless it is removed, it may accumulate to such an extent as to interfere with the intended operation of the ice maker.

lt is an object of this invention to prevent the accumulation of frost on ice makers and on the walls of the freezing compartments of refrigerators in which the ice makers are located.

it is a further object of this invention to provide a method of and means for collecting and disposing of water vapor condensate in the freezing compartment of a refrigerator without the need for frequent defrosting of the whole of such compartment.

Briefly, in accordance with this invention, the ice mold is provided with thermal insulation around the front, rear bottom and side walls thereof, the only portion of the ice mold that is exposed to the ambient of the freezing Patented Sept. `1.3, 1955 ICC.

compartment is Ithe open top` through which the ice pieces are removed. The t-hermalinsulation is encased in decorative insulating-casing members, which members hold the insulation in place and give the icemaker-an attractive streamlined appearance.

Also, in accordance with this invention, a portion of the liner of the freezing compartment in-which the ice maker is locatedis arranged-in `a manner that substan-` tially all of the water vapor from tzhe ice mold collects and freezes on this portion ofthe liner from whence the frost or ice is removed at frequent intervals and without defrosting the whole-,of freezing compartment liner. To this end, a ceilingmember ofthe freezing compartment directly above the ice mold is placed in good thermal contact with the` mold .so that the ceilingmember isA cooledby the same refrigerating coil that cools the mold whereupon the frost collects uponthis member, and each time thejice mold is heated to loosen the ice pieces therefrom, the ceilingmember is also heated to melt any frost that may have collected thereon. The ceiling member is otherwisethermally insulated from the icemold and fromthe other walls of the freezing compartment of the refrigerator; The defrost water from the ceiling member may be disposed of in any suit-v able manner. However, in accordance with this invention, the ceiling member is defrosted each time ice pieces are released from the moldY and, since the amountof defrost water is quite small, such water is conveyed di` rectly into the ice mold.

The invention together with its objects and advantages is set forth inmore technical detail in the following description and accompanying drawings wherein:

Fig. l is a partial front `elevation of a household refrigerator partly in section and showing the ice maker located in the freezing compartment thereof;

Fig. 2 is a detail vertical section taken substantially on line Zi-Z of Fig. l;

Fig. 3 is a front elevation of the ice maker and showing portions of the refrigerator in section;

Fig; 4 is a side elevation of the ice maker partly in section;

Fig. 5 is a transverse vertical section through the icc mold and a part ofthe refrigerator;

Fig. 6 is a rear perspective of a front closure member for the mold vinsulation and Fig. 7 is a schematicillustration of an ice maker and a wiring diagram of the controls therefor in accordance with the copending companion application of Harry C.'

Shagaloff, referred to above.

Referring now to Figs. 1 and 3 of the drawing, the icemaker indicated generally by reference .character 10 is located within the freezing compartment 11 of a household refrigerator 12, which compartment is closed by an outer door 13. A food storage compartment 14-is located below thefreezing compartment and is closed by an outer door 15. An insulating partition 16 sepa-` rates the freezing compartment from the food storage compartment. A decorative trim and thermal breaker strip 17 extends across the top and down the two sides of the freezing compartment at the front thereof. A similar breaker strip 18 extends around the front of the food storage compartment. The freezing compartment` is provided `with a liner having a top wall 20, a bottom wall 21, side walls 22 and 23 and a .rear wall 24. The top wall 2i) is provided with a recess portion above the ice maker, which recess portion is closed by av ceiling member indicated generally by reference numeral 25.

The top wall 20 of the freezingA compartment is Placed.

in thermal contact with a.` refrigeratingf coil 26 .and the bottom wall 21 of such compartment is ink thermal con-V tact with the second refrigerating coil 27, which coils are connected to a suitable refrigerating apparatus, not shown.

The food storage compartment 14 of the refrigerator is cooled by a refrigerating coil 28, provided with heat transfer lins 29, encased in a grill member 30. The bottom wall of the freezing compartment is provided with a depressed portion 31 having a conduit 32 extending downwardly therefrom and through the partition 16 between the freezing compartment and the food storage compartment. A drain plug 34 provided with flutes 3S inthe sides thereof is located in the depressed portion 31 and extends'through the conduit 32 into the food storage compartment. The grill member 30 is provided with a channel 36 along the bottom portion thereof and with a spout 38 that conveys defrost water to a cup 39, from whence the defrost water is conveyed to the rear of the refrigerator and disposed of in any suitable manner.

Only so much of the ice mold and ejector mechanism as is necessary for a complete understanding of this invention is illustrated and described herein.

Referring to Fig. the ice mold 40 comprises an aluminum die casting divided into a plurality of ice forming compartments 41 by transverse partitions 42. The ice forming compartments are generally semi-circular in vertical transverse section, and the partitions are tapered horizontally from the right to the left side thereof as viewed in Fig. 5. The partitions have substantially no taper in the vertical direction. The partitions are each provided with an upstanding projection 43 on the right side and with a weir or notch 44 in the left side thereof. The outer surface of each of the weirs is of the same general curvature as the inner surface of the ice mold compartments, and the inner surface of the weirs is substantially vertical. The mold is provided with an upstanding edge 45 along the left side thereof, and the end walls slant outward from right to left as viewed from the front in Fig. 5. A mold heater 46, in the form of a hairpin coil, is located in slots 47 in the bottom of the mold at each side thereof.

The mold rests on a refrigerated shelf 48 that is cooled by a refrigerating coil 49 also in the form of a hairpin. As shown, the refrigerating coil is formed out of round on one side for good thermal contact with the undersurface of the refrigerated shelf and for downward ow of refrigerant from the inlet to the outlet end of Such coil. The refrigerating coil is connected to a suitable refrigerating machine, not shown. As shown, the mold is provided with a plurality of bosses 50 projecting from the bottom thereof which pass through openings in the refrigerated shelf, and which clamp the mold to the shelf and the shelf to the refrigerating coil 49 by means of a clamp 51 which is held in place by a plurality of screws 52 threaded into the bosses 50. A mounting plate 53 made of thermal insulating material is attached to the front end of the mold by a plurality of screws 54. The rear ice forming compartment of the mold is closed by a combined closure member and mounting plate 55 that is formed of plastic or other thermal and electrical insulating material. The plastic closure member 55 is provided with a boss 56 having a downwardly and inwardly inclined opening therethrough for the reception of a water tube 57, and, as shown, the closure member is provided with an abutment 58 for locating the water tube.

The ejector mechanism includes a shaft 59 mounted for clockwise rotation at its front end in the front mounting plate 53 and at its rear end in the closure member 5S. VThe shaft has a at portion 60 on the upper part thereof, and is provided with a plurality of ejector blades 61, one for each ice mold compartment, at one side of the shaft. As shown, the ejector shaft is mounted olf center relative to the longitudinal axis of the mold and the blades are at an angle to the at portion of the shaft. For certain installation, it is advantageous to mount the ejector shaft on the longitudinal axis of the mold. An

' the vertical portion 73 of the ceiling member.

electric motor 120, shown only in Fig. 7, for driving the ejector shaft 59, is mounted on the rear wall of the refrigerator and is connected to the rear of the ejector shaft by a universal coupling, not shown. This electric motor is geared down from 3400 R. P. M. to approximately 2 R. P. M. and is of a type motor that stalls while energized when the ejector blades initially contact the ice frozen solid in the mold. An electric motor of this type is described and claimed in a copending companion patent application of Sven W. E. Andersson, Serial No. 325,145, filed December 10, 1952.

A stop mechanism 62 comprises a channel member 63 that is generally L-shaped in plan and is connected for pivotal movement by a pivot pin 64 to the upper right side of the rear closure member 55. A vane 65 made of a thermal and electrical insulating material is attached to the longitudinal portion of the channel member and projects downwardly therefrom into an ice storage receptacle 66. The channel member is provided with a rearieatrdly extending arm, not shown, that is adapted to be contacted by a cam member 67 mounted upon the ejector shaft S9. The cam is so shaped that upon rotation of the ejector shaft the cam contacts the rearwardly extending arm of the channel member and gradually raises the channel member to a substantially horizontal position. Then the cam leaves the arm and permits the channel member to fall by gravity to its normal position shown in Figs. l, 3, and 7. A mercury switch 68 is mounted on the transverse portion of the channel member by an adjustable bracket in a manner that when the channel member is in the position shown in Figs. 1, 3, and 7 the circuit through the mercury switch 68 is closed, whereas when the channel member is raised to a substantially horizontal position the circuit is open.

in accordance with this invention, the ceiling member 25 of the freezing compartment includes an arcuate sheet metal member 70 provided with a flange 71 at the lower right side thereof, which is attached by screws 72 to the top wall 2i) of the freezing compartment. A thermal bre ker strip 71a is placed between the flanged portions of the ceiling member 70 and the top wall 20. The opposite side of the ceiling member 70 is provided with a vertical portion 73, a horizontal portion 74 and a second vertical portion 75, which second vertical portion is placed in good thermal contact with the ice mold and secured thereto by a plurality of screws 76. A rear wall member 77, having an inwardly projecting flange 7S provided with thermal breaking projections 79, is attached by screws S6 to the rear wall 24 of the freezing compartrnent. Except for the short line contact between the projections 79 and outer rear surface of the ceiling member '73, the ceiling member and the rear wall member 77 are spaced from each other, and the space therebetween is in open communication on one side with the freezing compartment and on the other with the insulation surrounding such compartment. A Similarly flanged member 81 is attached to the upper front wall, not shown, of the reezing compartment.

A thermal insulating piece 82 rests upon the horizontal portion 74 of the ceiling member and extend along the length of the mold at the upper left side thereof. This insulating member is made of a piece of unicellular sponge rubber that is impervious to moisture and is sealed by a suitable cement to the left side of the ice mold and to A suitable material of which this insulating member may be made is known in the trade as Rubatex. A second thermal insulating member S3, also made of Rubatex, extends along the lower left side of the mold between the vertical portion 7S of the ceiling member and the upper portion of the left side wall 23 of the freezing compartment. A spacer 35 made of thermal insulating material is located between the left side of refrigerated shelf 48 and the left side wall 23 of the freezing compartment. An elongate insulating piece 86 of unicellular sponge rubber 5. is positioned betweentheunder surface of the refrigerated shelf 48, the clamp 51 and. the.refrigeratingcoil` 49. An L-shaped insulatingpiece .8.7, also madeof unicellular sponge rubber, is positioned .beneath the freezingl shelf and projects upward` at the-` right side thereof.

A strip88 of plastic or .other y.thermal insulating material is attachedy tothe right sideof the mold by screws 89 and is providedwith a vnotched portion 90 `along the upper inner edge thereof. A relatively rigid casing member 91, for` holding, the insulation in place and formed of ethyl celluloseor vother suitable material, has a ange portion 92 that ts within` thenotch 90 of theplastic strip and extends -downwardly Aalongthe right side of the mold,.

across thebottom of the mold andis attached to the left side wall A23.0f the freezingcompart-ment by screws 93. A closure member 95, also made of ethyl cellulose or other suitable thermal,insulatingmaterial, is attached to the front of the casing91.,v Thisl closure member is substantially cupfshaped with an4 openT side and includes a flange portion96 .along the bottom and. right sidethereof that telescopes within the front of the casing 91 and is attachedtheretoby aplurality of screws 97.

This invention, as-stated in thekv introduction, has particular use with `an. ice maker likethat disclosed in the above copending companion. application of Harry C. Shagaloif. Referring now to Fig. 7, wherein the Shagaloif ice maker is schematicallyillustrated, L1 and L2 are the two sides ofa 115 volt A1. C. supply circuit. 100 is a double pole double throw manually operated switch, shown in the onf position to operatel the ice maker. the fotf position the lower blade 100a of switch 100 will be at terminal `101, which is dead, and the upper blade 100!) will be at terminal 102;, which keeps the refrigerant compressor motor 104 running under the control of a box thermostat 105. Thus, in the off` position of switch'100` all circuits to the ice maker are broken, but the refrigerator continues to operate under the inuence of the thermostat105. Normally,l current is fed to the ice maker form L1 through switch blade 10017,v the connecting link 100C, switch blade 100aand terminal 103 of switch 100. lf the mercury switch' 68 is open, indicating that the storage receptacle 66 is full of ice cubes, the ice maker stands idle. If the mercuryswitch is closed, as shown in Fig. 7, nothing happens until; the mold thermostat 108 snaps the switchV 109 to the terminal 110 indicating that the water in the ic'e mold 4'0 has been completely frozen' into ice.

A double pole doublethrow push' button switch 114, operated automaticallyby the` refrigerator door 13, is shown in the4 closed door,position.

terminal 115 to terminal 116, which is dead, and the lower blade 114b snaps to terminalr117,` to energize the light 118 within the freezing compartment of the refrigerator. Thus, the ice maker cannot runwhile the refrigerator door 13 is open. With the refrigerator door 13 closed, the interior light 118, is deenergized and 'the ejector motor 120 and the mold heater 46 are energized. A single pole push button switch 114', shown only in Fig. l, energizes and deenergizes, the light 118 in the food storage compartment upon the opening and closing of the door 15. A high temperature limit switch 121, shown aheadl of the mold heater, is a thermostatic device which opens the heater circuit at about 100 F., and opens only in the event that the mold heater is energized tool long due to something having gone wrong with the controls.

Calling the starting position of the ejector shaft 59 the position it has when water is being frozenin the mold 40, and the previous batch of ice cubes is resting on-the ejector blades 61. When` the ice is completely frozen 1n the mold, the mold thermostat 108-snaps the switchf109 to terminal 110 energizing the ejector motor 120and the mold heater 46. Shortly after the ejector motor starts rotating the ejector blades 61, the ice falls from the blades into the storage receptacle 66. When the ejector motor 120 has rotated about 45 from the starting point, a cam In the open door f position, the upper blade 114'a ofswitch 114 snaps fromv 122b ,on1the motor shaft 120a closes a water'outlet valve.

124..` When the-ejector motor 120has rotated about 60` from starting position, a cam 122C on the motor shaft p 120a snaps a micro switch 125 from terminal.126 to` terminal- 127. This stops the compressor motor 1044 and energizes a thermostat reset heater 128. At the. 135 point of rotation, a cam 1225i on the motor shaft opens `a waterinlet valve 123 and water flows from .a sourceof t supply through the conduit 129 into the measuringvessel- ThemoldY heater 46 (300 watts) continues to heat the Rotation -of the ejector shaft continues, until at about 180 theejector blades 61 contact the solid ice in the mold 40 .and cause the energized ejector motory 120 to stall.`

mold, and the reset heater 128- (10 watts) continues to heat the mold thermostat bulb 108a so as to reset the,-

switch 109 to the position shown. Also, in this position theinlet water valve 1123 remains open feedinga measured.

charge of water from the source of supply to themeasur.- ing vessel 130. vessel 130, an expansible rubber diaphragm 131 is exe. panded forcing a piston 132 downward whichcompresses a spring 133, located in a cylindrical portion of the meas-` uring vessel.

When the ice is thawed loose in the mold, rotation` of the ejector motor continues whether or not the mold. thermostat 108 has reset. That is, current ows through. terminal if the mold thermostat has notV reset andu through terminal 111 if it has. The water inlet valve 123.

closes at about 225 of rotation of the ejector motor, leaving a ymeasured quantity of water stored in the measuring vessel-130.

When the ejector blades 61.reach the 27.0 point of` rotation, a cam 67 on the ejector shaft 59 quickly raises. the arm 62 and attached mercury switch 68 breaking the ejector motor circuit at that point-tv stat V108 has reset this does not stop the ejector motorl since it is getting current through terminal 111 from the micro` switch 125. But if the mold thermostat has. not` reset, openingof the mercury switch 68 stops the opera-- tion since the ejector motor has. been getting current from. terminal 110 of the mold thermostat 108.l The reset heater 128 remains energized, trying to reset the mold. thermostat and if it is successful, rotation of4 the, ejector continues and 'slowly sweeps the ice from the mold; butk if it is not successful it indicates that the mold thermostat. has lost its charge, cannot be reset, and the system. dies permanently, with the ejector motor and mold heater deenergized, the compressor motor deenergized, the thermo-- stat reset heater energized, and the inlet and outlet water valves closed. In this way a diaphragm system mayl be used in the mold thermostat which operates above atmospheric pressure and instigates an ice ejecting cycle on fallingpressure, while at the same time, if the pressure falls below normal a subsequent ejecting cycle is prevented from being started. That is, if the mold thermostat 10S" loses its charge, an ice release cycle will be instigated. re gardless` of whether or not the water in the mold is completely frozen; but the ejector motor will rotate only to the 270 point whereupon the mercury switch 68 is opened,'the ejector motor deenergized and no more water is supplied to the mold until the defective thermostat has been replaced.

Going back to where the mercury switch 68 opened,

' the ejector blades are at 270, but the mold thermostat.

108 is reset. Rotation continues since the ejector motoris getting current through terminal 111 from the micro.v switch 125. At about 300 of rotation the mercury switch 68 drops free of its cam 67 and its circuit is eitherl made or not depending onhow muchice is in the storage receptacle 66. The `outlet water valve 124 opens at about the 315 point of rotation and stays open until the 45 point of rotation of the next release cycle, permitting the measured charge of water tobe forced from the .measuring-v` vessel to the mold. Having made sure that the ejec- As the water ows intothe measuring,

If the mold thermotor motor is getting current from terminals 127 and 111, so at the 360 point of rotation, the micro switch 125 snaps from terminal 127 to terminal 126, deenergizing the ejector motor, the mold heater and the reset heater, and bringing the ejector blades back to the starting position with the batch of ice resting thereupon to bedried during the next freezing cycle, with the compressor motor 104 energized and the outlet water valve open.

In operation, by insulating the ice mold 40 and by placing the ceiling member 70 out of thermal Contact with the remaining walls of the freezing compartment 11, in the manner described above, the cooling effect of the refrigerating coil 49, that is in Contact with the refrigerated shelf 48 to which the ice mold is clamped, is used only to freeze the water in the mold and to chill the ceiling member 70, that is placed in thermal contact at its lower left side with the mold. ln this manner, the refrigerating effect of the coil 49 is conserved and the freezing of the water in the mold is faster than with an exposed mold. Also, each time the ice maker cycles, as described above, and the mold heating element 46 is energized, the ice pieces are thawed free of the mold and the ceiling member 70 is defrosted much quicker and more uniformly than if the mold were exposed to the ambient in the freezing compartment 11 of the refrigerator. lt is noted that each of the insulating pieces 82, S3, 86 and S7 is made of unicellular Sponge rubber that is impervious to moisture. So that, in use these members remain pliable and retain their insulating properties even though they be chilled to temperatures well below the freezing point of water and be subjected to water vapor or defrost water.

Assuming that the freezing compartment 11 of the refrigerator is maintained at a low temperature of between and 10 degrees F. by the refrigerating coils 26 and 27 and that the ceiling member 70, which is in thermal contact with the ice mold, is cooled to low temperatures by the refrigerating coil 49 during freezing cycles, the relatively warm water that flows from the measuring vessel 130 and the outlet valve 124 through the conduit 57 into the rear compartment of the mold, and from there to the forward compartments through the weirs 44, causes water vapor to rise from the mold and collect on the cold ceiling member 70 directly above the mold. Each time the heating element 46 is energized to heat the ice mold and free the ice pieces therefrom, the vertical portion 7S of the ceiling member that is in thermal contact with the left side of the mold is also heated, and this heat is transferred by conduction to the upper portion of the ceiling member, whereupon any frost that may have collected upon the ceiling member is melted. The defrost water trickles downwardly on the inner surface of the ceiling member onto the top slanting portion of the insulation member 82 and is conveyed therefrom to the ice mold, ln this manner, the ceiling member defrosted each time the ice maker cycles and ice pieces are removed from the mold.

The other walls of the freezing compartment of the refrigerator and the cooling coil 2S in the food storage compartment of the refrigerator may be defrosted in any suitable manner and at suitable time intervals independently of the defrosting of the ceiling portion 70 of the freezing compartment. When the freezing compartment 11 is defrosted, the defrost water passes through the flutes 35 in the plug 34 and is conveyed to the channel 36 along the bottom portion of the grill member 30, from whence this defrost water flows through the spout 38 into the cup 39, and from there to the rear of the refrigerator Where this defrost water is disposed of in any suitable manner.

From the above it is seen that water vapor that rises from the relatively warm water in the ice mold is collected on the ceiling member above the mold and each time the ice maker cycles and the mold is heated to thaw the ice pieces free thereof, the ceiling member is also heated and defrosted, and frost does not build up on the ice maker or on the adjacent ceiling member.

Y Without further description, it is thought that the features and advantages of the invention will be readily apparent to those skilled in the art to which this invention appertains, and it will, of course, be understood that changes in form, proportions and minor details of construction may be resorted to without departing from the spirit of the invention and scope of the claims.

What is claimed is:

1. A refrigerator having av freezing compartment bound by a plurality of walls and forming a space for the preservation of food, an open top ice mold within said compartment below a top wall thereof, means for freezing water into ice in the mold and for chilling the walls of said compartment below the freezing temperature of water whereby frost is collected thereon, and means operable responsive to the freezing of water in the mold for defrosting at least one of the walls of said compartment.

2. A refrigerator having a freezing compartment bound by a plurality of walls and having a space for the preservation of food, an open top ice mold within said compartment below a top wall thereof, means for freezing water into ice in the mold and for simultaneously chilling at least one wall of the compartment below the freezing temperature of water whereby frost is collected thereon, means for removing the ice from the mold through the open top thereof, and means operable responsive to the removing of ice from the mold for defrosting at least said one wall of said freezing compartment.

3. A refrigerator having a freezing compartment bound by a plurality of walls and forming a space for the preservation of food, an open top ice mold within said compartment, means for filling the mold with water, means for freezing the water into ice in the mold and for chilling at least one wall of the compartment below the freezing temperature of water vapor whereby frost is collected thereon, means operable responsive to the freezing of the water in the mold for freeing the ice therefrom, and means operable by the freeing means for defrosting at least said one wall of the compartment.

4. A refrigerator having a freezing compartment bound by a plurality of walls and forming a space for the preservation of food, means thermally insulating at least one of said walls from the remaining walls, an ice mold within said compartment, means thermally insulating the ice mold from the compartment, means for filling the ice mold with water to be frozen, refrigerating means for cooling the compartment and freezing the water in the ice mold, and means for heating the ice mold to free the ice therefrom and to defrost said one wall of the freezing compartment.

5. A refrigerator having a freezing compartment bound by a plurality of walls and forming a space for the preservation of food, an automatic ice maker within said compartment, said automatic ice maker including an ice mold, means for lling the mold with Water to be frozen, refrigerating means for freezing the water into ice in the mold and for cooling said compartment, means for thermally insulating the ice mold from the compartment, means operable responsive to the freezing of ice in the mold for heating the mold to free the ice therefrom, one of the walls of said compartment being so constructed and arranged as to condense water vapor thereon, and means operable responsive to the freeing of the ice from the mold for conveying the condensed water vapor to the ice mold.

6. A refrigerator having a freezing compartment bound by a plurality of walls and forming a space for the preservation of fool, an automatic ice maker within said compartment, said automatic ice maker including an ice mold, means for filling the mold with water to be frozen, refrigerating means for freezing the water into ice in the mold and for cooling at least one wall of said compartment, means for thermally insulating said one wall from the other walls of the freezing compartment, means for thermally insulating the mold from the compartment,

y means operable responsive to the freezing of ice in the mold for removing the ice therefrom, said one wall of the compartment being so constructed and arranged as to collect water vapor thereon, and means operable responsive to the removing of the ice from the mold for conveying the collected water vapor to the ice mold.

7. A method of retarding the accumulation of frost on the walls of a freezing compartment of a refrigerator which comprises cooling all of the walls of said compartment below freezing temperature whereby water vapor condenses and freezes thereon, thermally insulating one wall of the compartment from the other walls thereof, separately and intermittently cooling and heating said one wall whereby after frost of substantially a given thickness is formed on the remaining walls of said compartment any water vapor that enters the freezing compartment is collected as frost on said one wall when such wall is cooled and is conveyed therefrom as liquid when such wall is heated.

8. A method of collecting and removing moisture from a freezing compartment of a refrigerator containing an ice mold which comprises cooling all of the Walls of said References Cited in the tile of this patent UNITED STATES PATENTS 2,370,267 Starr Feb. 27, 1945 2,435,102 Rundell Ian. 27, 1948 2,443,203 Smith 2 June 15, 1948 2,509,610 Philipp May 30, 1950 2,563,093 Bayston Aug. 7, 1951 2,613,510 Morton Oct. 14, 1952 2,622,412 Staebler Dec. 23, 1952 2,682,155 Ayres June 29, 1954 2,692,482 Shoemaker Oct. 26, 1954