US2692482A - Multitemperature refrigerator - Google Patents

Description

96L 1954 M. G. SHOEMAKER MULTITEMPERATURE REFRIGERATOR 3 Sheets-Sheet 1 Filed June 7, 1951 INVENTOR. M41600 6: DWI/MAM;

BY @w Och 1954 M. G. SHOEMAKER MULTITEMPERATURE REFRIGERATOR 3 SheetS -Sheet 2 Filed June '7, 1951 i INVENTOR.

M/IZJ'UZ/l/ 61 )WOZ'MAAZ? BY Qua/w, M 2

Oct. 26, 1954 M. G. SHOEMAKER MULTITEMPERATURE REFRIGERATOR Filed June 7, 1951 3 Sheets-Sheet 3 INVEN TOR. Mam/v 6 Mam/mm? BY M Patented Oct. 26, 1954 UNITED STATE ates/s2 l NT OFFICE MULTITEMPEERATURE REFRIGERATOR Application .lune 7, 1951, Serial No. 230,357

7 Claims.

The invention set forth in the following specification relates to refrigeration, being concerned with refrigerators of the plural compartment type having provision for rapid and automatic removal of frost from the evaporator means utilized to produce refrigeration. More particularly, the invention has to do With improvements in plural compartment refrigerators of the type disclosed and claimed in the co-pending application of Elmer W. Zearfoss, Jr., bearing Serial No. 161,806, filed May 13, 1950, now Patent No. 2,647,375, issued August 4, 1953, and assigned to the assignee of the present invention.

As set forth in said co-pending disclosure, it is now Well recognized that it is desirable to provide not only a main storage compartment maintained at temperatures above the freezing point of Water, in order to provide for proper preservation of fresh foodstuffs, but also a compartment maintained at relatively low sharp-freezing tem peratures suitable for the preservation of frozen foods over long periods of As also considered in said earlier disclosure, a factory and inexpensive approach to the problem of providing compartments well adapted for storage of foods under such d' ferent temperature conditions is to provide within the cabinet a generally horizontal partition or baiiie which divides the space defined by the inner liner of the cabinet into a pair of compartments and which limits, but does not eliminate, circulation of air between said upper and lower compartments. In. an arrangement of this type the limited circulation of air referred to is relied upon to accomplish refrigeration of the main, higher temperature compartment, a low temperature evaporator either being disposed Within, or constituting the other compartment, and taking care of the frozen food requirements, Further, automatic defrosting of the said evaporator has been provided. in the Zearfoss apparatus by utilizing, in cooperation with the aforesaid baflie or partition, air propelling means operable to cause a circulatory flow of air from a restricted zone of the warmer compartment, past said evaporator, and back to said zone of the warmer compartment. Means is also provided to heat the circulating air, and the described construction has proven highly advantageous particularly in that effective and rapid defrosting is accomplished without unduly elevating the temperature of the warmer compartment. The arrangement is furt er characterized in that operation of the air propelling means, following termination of the defrosting operation, serves to restore the desired temperature conditions in the shortest possible time and to main" tain such conditions until the next defrosting cycle.

While the earlier construction constitutes a significant improvement in the art, the underlying principles of which are embodied in the apparatus of the instant invention, the above-described arrangement is subject to a difiiculty in that there is a tendency for melting of frozen foods to occur during defrosting of the evaporater. I have recognized that this problem may be completely overcome, and significant addi tional improvements effected, if the evaporator which cools the warmer compartment-through the agency of the aforesaid air propelling means is not required to perform the additional function of maintaining frozen foods. Particularly can improved results be obtained if a frozen food storage compartment is provided in which there occurs little if any accumulation of frost, under normal operating conditions, and as to which there is no need to effect a dc" frosting operation.

Accordingly, it is the broad object of the present invention to provide an improved plural compartment refrigerator having upper, lower and intermediate compartments one of which is especially Well adapted for the proper preservation of frozen foods, another of which is arranged to accommodate the ice cube receptacles (which formerly constituted source of free moisture present within the frozen food compartment, and therefore occasioned excessively rapid accumulation of frost within said compartment), and the t ird of which comprises the main food storage compartment and is cooled by air refrigerated within the ice freezing compartment. In the achievement of these general objectives, 1 have provided a cabinet having a pair of superposed partitions defining said upper, lower and intermediate compartments, said upper and lower compartments each being provided with evaporator means, the aforesaid means being utilized in novel combination with fan to produce-in response to temperature conditions prevailing within the intermediate compartment-a relatively low velocity circulatory flow of air around said upper partition, whereby air cooled within said upper, ice freezing compartment is effective to refrigerate said intermediate compartment. Although a single refrigeration system is utilized to refrigerate all three compartments, the lower compartment, being thermally isolated from either of the aforesaid compartments, is continuously maintained at temperatures in the sharp freezing range and requires essentially no defrosting. In common with the apparatus of the aforesaid Zearfoss disclosure, the air propelling means may be employed, if desired, in combination with air heating means.

By this invention there is further provided means for impeding the circulatory flow of air between the upper and intermediate compartments, except during periods of operation of the air propelling means. Under certain conditions of operation, particularly when the ambient temperature reaches relatively low values, it is desirable that there be no substantial interchange of air between the upper compartment and the intermediate compartment, in order to avoid any possibility of freezing the contents of the latter compartment, and the improvement last mentioned above insures proper maintenance of the temperature of the intermediate compartment by placing the heat exchange between the two compartments substantially under the control of the air propelling device.

In considering this invention it is to be borne in mind that the apparatus described hereinafter constitutes the first household refrigerator in which the necessary defrosting can be accomplished automatically Without any interference with either the proper preservation of frozen foods or with maintenance of the temperatures desired within the main food storage compartment.

The manner in which the foregoing objects and advantages of my invention may best be achieved will be more fully understood from a consideration of the following detailed description, taken together with the accompanying drawings, in which:

Figure 1 is a sectional view taken generally through the vertical mid-plane of a refrigerator embodying the invention;

Figure 2 is a view, on an enlarged scale, of the upper portion of the apparatus illustrated in Figure 1, and indicating in greater detail the apparatus providing for circulatory flow of air from the upper to the intermediate compartment;

Figure 3 is a sectional view taken generally as indicated by the line 3-3 applied to Figure 2;

Figure 4 is a diagrammatic representation of the refrigeration and control circuitry preferably employed in the apparatus of Figure 1; and,

Figure 5 illustrates, diagrammatically, a modified circuit arrangement which may be utilized.

Now making more particular reference to the drawings, and especially to Figures 1 and 2 thereof, it will be seen that the invention is therein illustrated as embodied in a domestic refrigerator comprising an outer shell IE9 and an inner shell or liner member II, spaced inwardly of and insulated from the outer shell ID by any suitable insulation, shown at I2. As is customary, a breaker strip I3 of low thermal conductivity extends about the forward edge of the cabinet and bridges the gap between the outer shell I0 and the inner liner II. The refrigerator also includes a recessed area or compartment housing a compressor I4, a condenser I5 being disposed in the form of a flue extending upwardly along the lower portion of the back wall of the outer shell I0. Both the compressor and the condenser may be of any desired type and, as will be understood, are connected in refrigerant flow circuit with evaporator elements presently to be described, the interconnecting conduits being omitted from Figures 1 to 3 to simplify the same. In particular accordance with my invention, the space within inner liner II is divided into upper, lower and intermediate compartments shown at I6, IT and I8, respectively, through the agency of a pair of spaced partitioning members, the upper of which appears at E9 and the lower at 28.

The intermediate compartment I8 would be provided with suitable shelving (not illustrated) and is adapted for the storage of fresh foodstuffs at above-freezing temperatures. The lower compartment I'I constitutes a sharp freezing zone intended to accommodate frozen foods stored over extended periods of time and, to maintain in said lower compartment the desired low temperature conditions, said compartment is provided with a generally L-shaped evaporator element 2i. In the upper part of the upper compartment I6 there is arranged a freezing evaporator or plate 22 spaced below the upper wall of the inner liner II and accommodating ice cube receptacles, one of which appears at 23. This latter evaporator is preferably of a width such as to span the distance between the sidewalls of the inner liner and means, including a door member Z land gasketmeans- 25, is employed to prevent access of moisture laden air to any but the downwardly presented surfaces of thesaid evaporator 22. The door'i l is of novelconfiguration, being adapted tocooperate with-the partition I9 during circulation of air thereabout, and Will be described more fully inv whatfollows.

The underlying, warmer compartment I8 is refrigerated by the evaporator plate 22 andto this end, and in general accordance with the apparatus of the said co-pending Zearfoss disclosure, provision is made to establish circulatory how of air around the partition. L9 in a manner now to be briefly described. The partition I9 is provided, in the central portionof its rear edge, with a generally circular opening within which is received an upstanding tubular collar 26 housing a motor 21 and an associated fan 28. The forward edge of the partition lies adjacent to the door 24 and, as appears to best advantage in.

Figure 3, this door is of unusual construction in that air circulated by the fan 28v through the compartment IS flows through the door 26, and is thence delivered to the underlying warmer compartment I8. As shown in Figure 3 the inner surface of the door is provided. with a pair of openings 29-29 spaced somewhat above the upper surface of the partition I9, and air entering the door structure through these openings flows upwardly across upstanding partitions shown at 36 and thence downwardly through the lower portion of the door. The air. flow through the door may be understood from considering the arrows applied to Figures 2 and 3. Since the only openings providing for communication be,- tween the compartment i6 and the compartment I8 are cylindrical fan collar or housing 26 and the door structure 24, and since these openings lie above the plane of the partition I9, air withinthe compartment I6 stratifies between the lower surface of evaporator 22 and the upper surface of the partition. As mentioned above, there is relatively little interchange of air in the absence of operation of the fan 28. As already set forth, this feature makes it possible to provide improved control of the temperature of thecompartment I8, regardless of fluctuations in the ambient temperature. As indicated later in this description, provision is made toactuate the fan 28 in response to increases in temperature of the compartment I8 above a predetermined value and, under normal refrigerating conditions when defrosting is not required, the fan operates intermittently directing air upwardly through the casing and ejecting the cooled air through the door 24 from whence it flows to the compartment It to refrigerate the same.

Returning now to a consideration of the novel compartmental ararngement of this invention, it will be seen that the sharp freezing compartment ll is completely isolated from the compartment l8 through the agency of the imperforate partition 26 and, as will be understood as the description proceeds, the evaporator 2| operates to maintain the desired low temperature condition within the compartment l'l without being adversely affected by the temperature conditions prevailing within the upper and intermediate compartments, even during defrosting of the evaporator 22. Since three superposed compart ments are provided it is not necessary to freeze ice within the compartment ll, nor is frozen food stored within the defrostible compartment and, as a consequence, need for defrosting the sharp freezing compartment if is virtually eliminated, and there is no tendency to melt frozen foods. It is also to be noted that the evaporator 22, which rises in temperature during defrosting, is spaced from the compartment ll.

Thus, although a single refrigerating system is effective to cool each of the three superposed compartments, it is possible to defrost the evaporator of one of said compartments without either interfering with the temperatures in the other two thereof or limiting the utility of any portion of the refrigerator.

Preferably, although not necessarily, a heater element is disposed within the upper compartment I6 to shorten the time required for defrosting the evaporator 22, and such a heater element is shown at El. As will clearly appear during description of the circuit of Figure l, the heater may be energized, concurrently with energization of the fan 23, in response to operation of any suitable apparatus, such for example as a clock, adapted to initiate a defrosting cycle. As fully set forth in the said Zearfoss disclosure there is a relatively shallow flow of air through the upper part of compartment it during defrosting, this shallow flow resulting from the fact that the circulating air, due to the action of the heater ti, is at an elevated temperature with respect to the colder air which has Stratified within the compartment it. By virtue of this shallow circulation, and also because of the rapidity of the defrosting operation and the complete isolation of the sharp freezing compartment ll, it is possible to defrost the evaporator 22 without any objectionable interference with the temperature desired in the lower and intermediate compartments if and I8.

Consideration will next be given to the refrigerating and control circuitry illustrated in Figure 4, and to the manner in which this circuitry is em loyed to refrigerate the three superposed ccrnpartznents of the cabinet and to accommodate defrost of the evaporator disposed within the upper compartment.

First making reference to the elements of the refrigeration system, it will be seen that the aforesaid compressor E i and condenser it are identified in Figure and that these elements are connected, through the intermediation of a capillary type flow restrictor (2 and a suction conduit with the evaporators 2i and 22. It is preferred to operate the evaporator 2i at a temperature somewhat below that of the ice freezing and air cooling evaporator 22 and, to this end, an additional capillary restrictor 34 is interposed between the two evaporators. As regards the refrigerating cycle, the operation of this system is entirely conventional in nature and need not be described in detail herein. It will be noted that cycling of the compressor M is controlled by a temperature-responsive switch element 35 which is of known type, responsive through the agency of a conventional control bulbto the temperature of the sharp freezing evaporator 2!. The switch element 35 intermittently connects the compressor [4 across the line L through the right-hand blade 36 of a doublepole, double-throw switch 31 which latter, during normal refrigeration, occupies the right-hand position illustrated in full lines in the drawing. The main control switch 31 may conveniently be actuated by any suitable device for initiating a defrosting operation such, for example, as a clock (not shown), which device is effective to move the switch to the left-hand dotted-line position when defrosting of the upper evaporator 22 is required. When the main control switch 3'! occupies the position illustrated in full lines, it will be observed that the fan motor 2i may be connected across the line L through the contacts of a second temperature-responsive control device 83. The control, or feeler bulb, of the device 39 is responsive to the temperature of the air Within compartment it and initiates operation of the fan when the temperature of said air reaches a predetermined upper limit. Further, when the main switch 3'! is in the position shown, the heater 3i is not energized.

When defrosting is required and the main switch 3? has been moved to the left-hand dotted-line position, the fan motor 27 is placed directly across the line through switch blade 33, no longer being under control of the device 39, and the heater 3i is connected across the line through the switch blade 36. During the entire defrosting operation, which may be terminated in any desired manner and preferably by contacts actuated by the above-mentioned clock, the circuit to the compressor it remains open. The circulatory flow of heated air which now takes place around the partition E9, in the manner fully set forth above, defrosts the evaporator 22 in a period of time which is of sufliciently brief duration that there is no objectionable rise in temperature within the heavily insulated sharp free ing compartment ll. This time period may,

for example, be of the order of five to ten minutes.

As will be apparent from inspection of the drawings, and particularly from Figure 3 thereof, the water which results from the defrosting opera tion drains downwardly from the upper surface of the baffle if! and is delivered to a receptacle it hrough a pair of small openings 4!.

For certain types of service it may be desirable to defrost the upper evaporator while continuing the operation of the lower evaporator, and with out resort to means for heating the air which is circulated to effect the defrosting. Lack of such heating may be of advantage under some conditions of operation and, while elimination of the heater serves to lengthen the defrosting time, the effect which this might have upon the temperatures desired within the sharp freezing compartment I! is offset in this embodiment by maintaining the evaporator 2| of said compartment in operation during the defrosting cycle. Such an embodiment of the invention is diagrammatically illustrated in Figure 5, in which figure 7" those refrigeration and electrical control ele ments, which have a counterpart in the primary embodiment already described, are designated by similar reference characters including the subscript a. In the second embodiment the refrigeration apparatus is essentially similar to that illustrated in Figure 4, including compressor, condenser, evaporator, and restrictor elements shown, respectively, at Ma, [a, 2 la, 22a and 32a. The normal functioning of these elements will be understood without description, but it will be observed that the system further includes a by-- pass passage 4|, at least a portion of which is of capillary size. One end of this passage is connected between evaporators 2 la and 22a, and the other end thereof isin free communication with an accumulator 42 disposed in the main capillary tube 32a. Under normal operating conditions, that is; when defrosting is not required, a small amount of gaseous refrigerant only will flow through the by-pass passage 4!, this flow being in amount insuificient to interfere with proper refrigeration.

Under such normal operating conditions, the main control switch 31a occupies the right-hand, full-line position illustrated in Figure 5. The compressor Ma then cycles in normal manner, through its temperature-responsive control device 35a, and the fan motor 21a may be connected across the line L through the left-hand blade of the main switch 31a, the fan also being under the control of a second temperature-responsive device 39a which may be identical in construction and operation to the device 39 of Figure 4. As will be understood without further description the functioning of this system, under normal refrigerating conditions, does not differ from the operation already described with respect to the primary embodiment. Although the embodiment of Figure 5 does not include means for heating the air circulated around the bafile 59, there is included a' heater 43 which is disposed in high heat exchange relation with the upper portion of the capillary passage 32a. This heater, when energized, is effective substantially to prevent flow of liquid refrigerant into the evaporator 2211, as a result of the gas binding caused by energization of the heater. This latter heater 43 is, of course, energized only when defrosting of the evaporator 22a is required. and occurs when the main switch 31a occupies the left-hand dotted-line position. When the switch occupies this latter position, the heater 43 is connected directly across the line through the righthand blade of the main switch 37a and, as was the case in Figure 4, the fan cycling device 39a is short-circuited and the fan motor 21a is placed directly across the line through the left-hand blade of switch 31a. Under these conditions the defrosting operation is carried out by virtue of circulation of relatively warm air from compartment [8 in heat exchange relation with theevaporator 22a, and the compressor Ma continues to cycle through its control 35a, the liquid refrigerant flowing from the condenser Ida by-passing the upper evaporator and entering the lower evaporator 2 la through the aforesaid passage M1. As indicated hereinabove, this apparatus is advantageous in that a defrosting operation is carried out without heating any of the air within the refrigerator and there is, again, no interference with the temperature conditions desired within the lower sharp freezing compartment. In the light of the foregoing description it will be understood that by the present invention there isprovided novel and advantageousrefrigera-- tion apparatus'of the multiple compartmenttype.

The apparatus is particularly characterizedi-in that manual defrosting of any portion of thetre-= frigerator is eliminated, and an automatic" defrosting operation is periodically carried out within one zone of the refrigerator withouteither interfering with the temperatures desired in other portions of the refrigerator, or limiting theutilit'y of any compartment thereof.

I claim:

1. In refrigeration apparatus: a pair of parti tions disposed in spaced relation and dividing the space within said apparatus into a cooling compartment, a frozen food storage compartment, and a fresh food storage compartment disposed adjacent said cooling compartment. and adapted to be maintained at above-freezing temperatures; refrigerating apparatus includinga pair of evaporator elements one of which is disposed in heat exchange relation with said cooling compartment and the other of which is disposedin heat exchange relationwith said frozen food storage compartment, said evaporator elements being op-- erative to maintain said compartments attheir respectiverefrigerating temperatures, said frozen" food storage compartment being substantially isolated from either of the other compartments above-mentioned; means adapted to utilize air from said fresh food storage compartment in the removal of frost from the'evaporator element of said cooling compartment, said last means comprising; air propelling means cooperable withthe partition disposed between said fresh food;

storage compartment and said cooling compartment to produce a circulatory flow of air from said fresh food storage compartment around'said last-mentioned partition and into and throughsaid cooling compartment; and means for interrupting the normal operation of at least the evap-' orator element of said cooling compartment dur ing a defrosting operation.

2. In refrigeration apparatus: a pair of partitions disposed in spaced relation and dividing the space within said apparatus into a cooling compartment, a frozen food storage compartment, and a fresh food storage compartment located between said two compartments aforesaid; refrigerating apparatus including a pair of evaporator elements one of which is disposed in heat exchange relation with said cooling compartment and the other of which is disposed in heat exchange relation with said frozen storage compartment, said evaporator elements being operative to maintain said compartments at their respective refrigerating temperatures, the partition disposed between said fresh food storage compartment and said frozen food storage compartment being thermally insulated and substantially preventing temperature changes from taking place within said frozen food storage compartment as a result of changes in the temperature of said fresh food storage compartment; means adapted to utilize air from said fresh foodstorage compartment in the removal of frost fromv the evaporator element of said cooling compartment, said last means comprising; air propelling, means cooperable with the partition disposed between said fresh food storage compartment and said cooling compartment to produce a circulatory flow of air from said fresh food storage compartment around said last-mentioned partition and into and through said cooling compartment; and? means for interrupting the normal operation at 9 least the evaporator element of said cooling compartment during a defrosting operation.

3. In refrigeration apparatus: a pair of partitions disposed in spaced relation and dividing the space within said apparatus into a cooling compartment, a frozen food storage compartment, and a fresh food storage compartment located between said two compartments aforesaid; refrigerating apparatus including a pair of evaporator elements one of which is disposed in heat exchange relation with said cooling compartment and the other of which is disposed in heat exchange relation with said frozen food storage compartment, said evaporator elements being operative to maintain said compartments at their respective refrigerating temperatures, the partition disposed between said fresh food storage compartment and said frozen food storage compartment being thermally insulated and substantially preventing temperature changes from taking place within said frozen food storage compartment as a result of changes in the temperature of said fresh food storage compartment; means adapted to utilize air from said fresh food storage compartment in the removal of frost from the evaporator element of said cooling compartment, said last means comprising; air propelling means cooperable with the partition disposed between said fresh food storage compartment and said cooling compartment to produce a circulatory flow of air from said fresh food storage compartment around said last-mentioned partition and into and through said cooling compartment; and switch means operable, when defrosting is required, to interrupt the normal operation of the evaporator element of said cooling compartment and to provide for continuance of the normal operation of the evaporator element of said frozen foot storage compartment.

4. Apparatus in accordance with claim 1, further characterized in that said last-mentioned means is effective to interrupt the normal operation of both of said evaporator elements during a defrosting operation, and in which apparatus there is further included means for accelerating the said defrosting operation, said accelerating means comprising means for heating the circulatin air.

5. Apparatus in accordance with claim 3, and further characterized by the inclusion of capillary restriction means normally operable to feed liquid refrigerant to both of said evaporator elements, said apparatus further including means for applying heat to a portion only of said restriction means to block the flow of liquid refrigerant to the evaporator element of said cooling compartment only, and said switch means being operable to energize both said heating means and said air propelling means whereby to initiate a defrosting operation.

6. In a refrigerator, a cabinet having a pair of superposed partitions defining upper, lower and intermediate compartments within the cabinet, the upper partition being constructed and arranged to provide for limited interchange of air between said upper and intermediate compartments and the lower partition being imperforate and presenting substantial thermal impedance between said lower and intermediate compartments, refrigerating apparatus including a pair of evaporators one of which is effective to cool the upper compartment and the other of which is elfective to cool the lower compartment, said apparatus being operative to cool said lower compartment to a temperature substantially below freezing and to cool said upper compartment to a freezing temperature somewhat above that of said lower compartment, means for maintaining said intermediate compartment at a non-freezing temperature, said means comprising air propelling means cooperable with the upper partition to produce, in response to temperature conditions prevailing within said intermediate compartment, a relatively low velocity circulatory flow of air around said upper partition, the construction and arrangement being such that air cooled within said upper compartment is effective to refrigerate said intermediate compartment without interfering with the low temperature conditions prevailing within said lower compartment, and means for utilizing air from said intermediate compartment in the removal of frost from the evaporator of said upper compartment, comprising, means adapted to heat the circulating air, and a switch device eifective to energize said heating means and to terminate normal operation of at least the evaporator of said upper compartment.

'7. In a refrigerator, a partition dividing the space therein into upper and lower compartments the upper of which is provided with evaporator means normally maintained at sub-freezing temperatures and upon which frost collects, intermittently operable air propelling means cooperable with said partition to produce a circulatory flow of air around said partition from the lower compartment through said upper compartment in heat exchange relation with said evaporator means and thence returning to the lower compartment, a door closing said upper compartment, and means, including said door, eifective to promote stratification of air within said upper compartment and to impede the said circulatory flow of air, said door being provided with air ingress and egress openings, said ingress opening being disposed above the level of said partition and said egress opening providing for delivery of circulating air to said lower compartment during periods of operation of said air propelling means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,823,002 Replogle Sept. 15, 1931 2,107,076 Mason Feb. 1, 1938 2,382,084 Mathews Aug. 14, 1945 2,463,835 Warren Mar. 8, 1949 2,511,419 Smith June 13, 1950 2,539,105 Rosebrook Jan. 23, 1951 2,546,363 Jaeger Mar. 27, 1951 2,552,345 Philipp May 8, 1951

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