US3005321A

US3005321A - Multiple temperature refrigerator

Info

Publication number: US3005321A
Application number: US835934A
Authority: US
Inventors: Michael H Devery
Original assignee: Philco Ford Corp
Current assignee: Space Systems Loral LLC
Priority date: 1959-08-25
Filing date: 1959-08-25
Publication date: 1961-10-24
Anticipated expiration: 1978-10-24

Description

Oct. 24, 1961 M. H. Dr-:vERY 3,005,321

MULTIPLE TEMPERATURE REFRIGERATOR HGENT Oct. 24, 1961 M. H. DEVERY MULTIPLE TEMPERATURE REFRIGERATOR 3 Sheets-Sheet 3 Filed Aug. 25, 1959 HGENT tet 3,@21 Patented Oct. 24, 1961 vania Filed Aug. 25, 1959, Ser. No. 835,934 4 Claims. (Cl. i2-186) This invention relates generally to the teld of refrigeration and more particularly to an improved method of and means for refrigerating plural compartment refrigerators.

It is now recognized that it is desirable to provide within a refrigerated cabinet not only a food storage compartment maintained at temperatures above the freezing point of Water, in order to provide 4for the proper preservation of food stuffs which should not be subjected to subfreezing temperatures, but also a compartment maintained at sub-freezing temperatures suitable for the preservation of frozen foods over long periods of time.

A technique presently employed for comparting the refrigerator is to use an insulating baille to partition the cabinet into upper 'and lower food storage zones. A widely used refrigerating arrangement provides for a predetermined leakage of refrigerated air from the cooler chamber to the warmer. This arrangement while satisfactory from many standpoints results in a reduc-tion in the temperature control over each of the food storage compartments, a condition which has heretofore been remediable only by the use of separate cooling elements in heat exchange relation with each of the refrigerated zones, a solution which is costly and space consuming.

It should also be understood with respect to constructions of the last mentioned type that without resort to independent cooling means the recovery time o-f the dependent warmer compartment is not `as rapid as it should be under many conditions of operation. The temperature of this compartment can become unduly elevated by the inow of warm air from. the room in which the refrigerator is located, the interchange of air between compartments under such conditions not being suiciently rapid to maintain the required protective food storage temperatures.

On the other hand accepted methods of providing forced draft interchange of refrigerated air between compartments utilizing a single cooling element, in an effort to improve recovery time of the dependent chamber, results in dehydration of the food within the food storage compartment through condensation of the airs moisture upon exposed cooler surfaces of the cooling element.

Accordingly, it is an object of invention to provide a novel single-evaporator refrigerating system which achieves complete structural isolation between refrigerator and freezer compartments, while providing selective cooling of each compartment in response to the individual temperature conditions prevailing therein.

it is another object of this invention to provide a singleevaporator cooling system which insures separate and controlled cooling of each compartment, in addition to eliminating the problem of food dehydration.

It is a still further obiect of this invention to provide a single-evaporator refrigerating system which can be readily associated with and removed from the refrigerator as a unitary structure and which provides substantially completely selective refrigeration of a plural compartment refrigerator.

Another but subordinate object of this invention is to provide a unitized inexpensive refrigerating system of extreme structural compactness and simplicity.

These and other objects within contemplation will be apparent by reference to the accompanying detailed de@r scriptiou and drawings in which: L;

FIGURE 1 is a longitudinal sectional view taken geilorally through the medial plane of a refrigerator em,- bodying one form of the invention, certain control circuitry being illustrated diagrammatically; lf;

FIGURE 2 is an exploded View of a unitized, singlje' evaporator cooling system made in accordance with present invention; j;

FIGURE 3 is a perspective showing diagrammatically illustrating one mode of installing the unitized coolinfg system within a plural compartment refrigerator;

FIGURE 4 is a sectional view taken along the cutting plane 4--4 of FIGURE 3 depicting certain features of construction of the refrigerator inner liner; and

FIGURE 5 is a detailed sectional view (with the elefments of the rcfrigerating system shown in elevation and in installed position) of the freezer portion of refrigerator shown in FIGURE l. "if

Now making more particular reference to the drawings and especially to FIGURE l, it will be seen that the invention is illustrated as embodied in a domestic refrigerator here chosen for illustrative purposes as an cubic foot box having a 6 cu. ft. freezer and a 12 cu. ft. food storage compartment. The box comprises an outer` shell 10 and an inner shell or liner member 1:1 shaped as shown in FIGURE 4 and spaced inwardly of and iiisulated from the outer shell 10' by any suitable insulation shown at 12. As is customary, a breaker strip 13 of low thermal conductivity extends about the forward edge of the cabinet and bridges the gap between the outer shell 18 and inner liner 11. The refrigerator also includes a machine compartment 14 housing an asserrxifbly consisting of the motor-compressor unit 15, fan 16 and iin-tube condenser 17, the construction being adapted for forced draft operation of the high side of the system. The compresso-r and condenser may be o-f any desired type, and as will be understood, are connected in refrigerant iiow circuit with the evaporator 18, the connecting tubing and auxiliary components being omitted from FIGURE l for clarity of illustration, the cifcuitry being shown in detail in FIGURES 2 and 5,

The space defined by the shell 10 is subdivided into a lower freezer compartment 19 and an upper, abovefreezing compartment 2li by means of the partitioning wall 21. Each of the compartments is provided with its

own door

22 and 23, respectively, adapted to seat in air tight closure against the cabinet in the plane of the breaker strip 13. 5"'

In the embodiment shown the evaporator 118 is positioned in high heat exchange relation with the freezer compartment 19 in the novel manner hereinafter dei scribed. lt should be understood however that while the invention is illustrated in connection with a so-calie'd upside-down refrigerator it is not to be considered as being limited to such use, the invention being applicable to refrigerators of alternate design. In the construction shown the compartments 19 and 2) share a common cooling plenum 25, within which is located the evaporator 18. *f

The plenum 25, in particular accordance with one aspect of the invention, is formed as part of a singleevaporator unitary refrigerating system, shown in exploded View in FGURE 2, which can be readily asso*- ciated with and removed from a multi-chamber refrigerator in the manner clearly indicated in FIGURE 13. This system, in conjunction with air moving means such as a pair of fans, provides cooling of each compartment selectively and in response to the individual temperature conditions prevailing in each thereof. 9.1

The cooling plenum is defined by baies 26 and' 27; the construction being most clearly shown in FIGURE 5. Bafe 27, in cooperation with ducts 2S formed by the juncture of the metal food storage compartment shell 29 and the preformed ribs of liner il, provide a substantially closed ow circuit for refrigerated air around the shell 29 and back to the cooling plenum 25. One pattern of ribbing 30 designed to insure uniform distribution of refrigerated air over the surface of the food compartment shell 29 is shown in FIGURE 4. A second independent flow route for the circulation of refrigerated air between the freezer 19 and plenum 25 is provided by

ports

31 and 32 formed in bale 26. This baille, forms the dividing wall between the freezer compartment 19 and cooling plenum chamber 25. Controlled movement of air through the two systems is accomplished by the use of strategically positioned

fans

33 and 34.

`In the illustrated embodiment the desired selectivity of ow is attained by placing a fan in communication with each of the mentioned passageways in the locations shown in FIGURES l and 5. Fan 33a which controls the refrigeration of the freezer compartment i9 is disposed centrally at the upper rear of the freezer compartment, its :b'lading being positioned within port 31 in the plane of ba-le 26. A fan having a capacity of 30 c.f.m. is adequate for refrigerating the freezer compartment. Operation of this fan produces circulation of air between the freezer and the cooling plenum 25, the direction of flow being indicated by the arrows shown in FIGURE 5. The bladin-g of fan 34, on the other hand, the motor housing of which is seated within the foamed plastic core 35 of the detachable wall plug (see FIGURE 2) is positioned within port 37 of the rearmost baffle 27, and is mounted and rotated in such direction that, when energized, air is circulated upwardly through ducts 23 surrounding the food compartment 20 and back to the cooling plenum 25. The required capacity of this fan is vabou-t twice that of the freezer fan and it may be of the impeller type (not shown) when the cabinetry conveniently admits of such construction. The fiow pattern induced by fan 34 is schematically indicated by arrows in FlGURE l.

To improve the heat exchange `relation between the structurally isolated food storage compartment 2d and the refrigerated air surrounding it, the shell 29 is preferably made of aluminum or other material having low thermal impedance.

As will be understood from what follows, by employing the method of the present invention the problem of food dehydration in both freezer and refrigerator is eliminated as is the need for a separate cooling eflement with Iits expensive and hard to assemble complex of tubing. In addition the unique arrangement shown provides separate and differential cooling of each compartment substantially independently of the refrigeration needs of the other in a manner insuring minimal recovery time in each compartment.

A satisfactory control circuit for accomplishing selective refrigeration is described below, it being understood that, insofar as the concepts of this invention are concerned, the circuitry is merely illustrative of one convenient mode of achieving the desired result.

Referring to FIGURE l, it will be noted that the refrigerator is provided with `a trio of temperature-

responsive control elements

40, 41 and 42, each of said elements, through the agency of conventional control bulbs, being adapted to initiate operation of instrumentalities within `the system. Element 4@ for example is provided with a control or feeler bulb 43 disposed in heat exchange relation with the surface of evaporator 18 the bulb being partially sheathed in material of low heat conductivity to insulate it from the air stream passing over the evaporator, for reasons hereinafter set forth. When the temperature of the evaporator has risen sufciently to expand the bellows of element 44B the contacts of switch 44 are closed placing the motor-compressor unit 1S across the line.

Similarly bellow elements 4l and 42 are respectively provided with feeler bulbs `46 and 47. When the temperature of the food compartment 2d has risen to a predetermined value, bellows 42 closes the contacts of associated switch 43 energizing fan 34, resulting in circulation of cooling air through ducts 28.

Control element 41 is likewise actuated when the temperature within the freezer compartment rises above a predetermined value. When this occurs contacts 5=1 are closed energizing fan 33 which in turn initiates circulation of air between the freezer and cooling chamber. As an additional refinement the circuit to each fan is completed through a door operated switch 52 of conventional type which is maintained in closed position when door 22 is closed, and which opens the circuit to the` fans when the freezer door is opened in order to prevent loss of refrigeration through the expulsion of cool air, or the drawing in of warm air by the operating fans.

The arrangement described provides the desired selectivity of control by insuring susbtantial isolation of the air in the different cooling systems while realizing the advantages of single-evaporator economy, localization of frost in a zone outside the refrigerated compartment without food dehydration and minimal recovery time of the separate cooling chambers through utilization of the full cooling capacity of the evaporator to meet the individual refrigeration demands of each chamber.

To facilitate a clearer understanding of the invention a representative set of operating parameters and conditions will be described, the refrigerator chosen for illustration being the above mentioned 18 cubic ft. box having a 6 cu. ft. freezer and a l2 cu. ft. foot storage compartment. Preferably the foot storage temperature sensing element 47 is designed to operate over a temperature range of from 34 to 40 F., the bulb being positioned within the upper, warmer part of the food compartment.

In accordance with the invention the temperature of the food storage compartment inner walls, formed by tub 2g", are maintained at a temperature above the freezing point of water. By isolating the air within the refrigerator compartment from the cooling coil 18 and maintaining the compartments inner walls at a temperature above freezing, lthe problem of frost accumulation, and consequent excessive dehydration, is completely avoided.

Moreover, this arrangement insures that the humidity will not become excessively high by promoting condensation of warm humid air entering the enclosure on its contact with inner wall surfaces maintained at temperatures below the airs dew point. Where moisture accumulation brought about by this process may become excessive, as might be the case in certain geographic areas, the surplus water can readily be removed by means well recognized in the art, as for example by use of a sump 29' and appropriate drain means not shown.

The freezer temperature is controlled by the bulb 46 which has an operating range of 0l to 10 F., while the surface temperature of evaporator 18, positioned within the cooling plenum 25 is monitored by a temperature sensing bulb 43 operating between 0 and -15 F., the latter bulb controlling the operation of the motor-compressor unit l5.

When the system is initially energized the motor-compressor unit l5 and

fans

33 and 34 are simultaneously activated each fan circulating refrigerated air to its respective compartment substantially independently of the other. When the predetermined temperature conditions of each compartment are met, the fan associated with that compartment is automatically shut olf, for example, if the refrigerating conditions of the food storage compartment have been satisfied the bellows 42 associated with that compartment constricts, opening the electrical connection to fan 34.

The freezer in the meantime maystill requlre additional refrigeration in which case fan 33 remains energized circulating air between the freezer andevaporator 18 until the desired temperature conditions of that particular compartment are established. When this occurs the electrical connection to fan 33 is interrupted in a manner similar to that described for fan 34. The compressor may continue to run for a brief interval of time after freezer temperatures have been reached, until the evaporator reaches some predetermined lower temperature as for example -15 F.

To lavoid overloading the compressor, where heavy usage results in a condition in which refrigeration in one or the other of the compartments is required immediately after shutdown of the compressor, the sensing element 43 mounted to the evaporator is insulated from the ambient air by a protective sheath to provide a thermal time delay of from five to eight minutes this technique being well known in the art. By this means the relatively Warm air which is drawn into the cooling plenum from, for example, the food compartment cooling ducts, does not result in immediate energization of the compressor and permits pressure equalization within the refrigeration lines before the next cycle of operation is initiated. Moreover, this expedient enables full use to be made of the residual cooling capacity of the evaporator which is designed to have sufficient thermal mass to provide the required refrigeration during unusual operating conditions of the nature described.

Constructional details of this unique refrigerating system are shown in FIGURES 2 and 5, the system being designed so that it can be completely assembled, sealed, and tested prior to its insertion within the structure being refrigerated. One construotional arrangement is to consolidate the elements comprising the cooling chamber into a readily insertable plug 60. This plug, shown in exploded view in FIGURE 2, may conveniently consist of a steel plate or shell 6l having mounted thereto an expanded plastic foam facing or core 62 provided with suitably molded cavities l63. The core may be made of any of numerous types of expandable foamed plastics, for example, to mention a few, phenolic, styrene, vinyl and isocyanate, in addition to the reactant type plastic mixtures, as exemplified by allsyd-resin-meta-toluene-diisocyanate. 'I'he cavities formed in this core receive the various circuit components such as the defrost valve 64, accumulator 65, tubing 66 and refrigerator fan 34. The components when positioned within these respective cavities are securely held in place by a mating foamed plastic slab 67, containing a pattern of cavities similar to that found on core 62, the components being sandwiched therebetween. The face of slab 67 which confronts baille 27 is centrally relieved to provide side rails 71 against which baille 27 seats to form the air passageway 72. Positioned forward of baille Z7 is the evaporator 18 followed by baille 26, the entire assembly being suspended on bolts 73 secured to fasteners 74 (see FIGURE 5) carried Iby Masonite strips 75 mounted to the steel plate 61.

To improve the support strength of the bolts they are provided with a nut and Washer assembly 76, located on an opposite face of the support in opposed, spaced relation to each fastener, the assembly being drawn down snugly yagainst the support '75 to form a compressive lock. Spacers 77 may be used to position baille 26 relative to the evaporator 18, and freezer fan 33 may conveniently be mounted to the evaporator top. The motor housing of fan 34 lis removably seated within a suitable cavity provided in core 35. The fan is secured -by screws 80 fitted into internally threaded bushings 81 entrapped within the body of the core. The assembled unit ready for installation is shown in FIGURE 3.

Appended to the assembly 60 is the high side of the system comprising the motor-compressor I5, condenser 17 and fan 16, these `units being mounted on a common frame 82 which in turn is mounted to the assembly 60 by metal support braces 83.

The unit as thus assembled may be easily inserted within the cavity 84 provided in the rear wall of the refrigerator cabinet. When inserted the unit is locked in place by simply screwing the apertured ange of steel shell 61 to the rear wall of the refrigerator and fastening frame 82 Within the machine chamber 14. To improve the seal between the rear wall of the refrigerator and the flange 86 the mating surface of the wall may be coated with yany one of a number of well recognized sealants, such as for example permagum. The braces 83 may be retained -as a permanent part of the installation or be removed for use in subsequent installations.

To facilitate alignment of baille 27 with the lower rear edge portion 89 of shell 29, the baille is contoured at 90 to receive the tub edge. To compensate for tolerance variations while at the same time insuring substantially air tight seating of the baffles, the baffles are provided with squeeze-like gasket element 91, which during insta1- lation act to seal olf the cooling plenum from the remainder of the system.

In summary there is provided a unique single-evaporator refrigerating system which can be readily associated with and removed from a refrigerator. This system through a novel arrangement of fans provides substantially completely selective refrigeration of a plural cornpartment refrigerator having the advantages detailed above.

Although the invention has been described with particular referenc to specific practice and embodiments, it will be understood by those skilled in the art that the apparatus of the invention may be changed and modified without departing from the essential scope of the invention as defined in the appended claims.

I claim:

1. In a plural compartment refrigerator, the combination comprising: duct means in heat exchange relation with exterior surfaces of one of said compartments; a plenum containing an evaporator mounted to a removable rear wall portion, said evaporator being disposed in high heat exchange relation with the other of said compartments and separated therefrom by. a partition apertured to provide a passage for the circulation of air between said plenum and said other of said compartments; means forming a communicating passageway between said plenum and duct means; and air circulating means disposed in each of said passages selectively to control the movement of refrigerated air therethrough in response to the individual temperature conditions of said compartments.

2. In a refrigerator having a freezer and food storage compartment, the combination comprising: air conduit means for piping refrigerated air around said food storage compartment; a cooling plenum disposed in high heat exchange relation with said freezer compartment and containing an evaporator carried by and bounded on one side by a separately formed, removable rear wall portion of said refrigerator and on an opposite side by a baille forming the rear wall of said freezer compartment, and said baille being apertured to permit circulation of air between said plenum and freezer, means providing a communicating passage between said plenum and conduit means; and a pair of fans operative to force air through said plenum to provide substantially completely selective refrigeration of said compartments in response to temperature conditions prevailing in each thereof.

3. In a refrigerator having a freezer and food storage compartment, the combination comprising: duct means in heat exchange relation with exterior surfaces of said food storage compartment; a single-evaporator refrigerating assembly positioned within a suitable opening provided in the rear wall of said freezer compartment, said assembly comprising, an insulative plug sealing said opening, an evaporator and baille, said plug and baille cooperating with interior wall portions of said freezer compartment to form a separate cooling plenum within which said evaporator is housed, said bafe being apertured to provide a path for the circulation of air between said freezing compartment and plenum and said assembly being further provided with conduits communicating with said duct means to form a closed path of ow for the circulation of refrigerated air from said plenum through said duct means; and a fan disposed in each of said paths providing substantially completely selective refrigeration of said compartments in response to temperature conditions prevailing in each thereof.

4. In a plural compartment refrigerator, the combination comprising: duct means in heat exchange relation with one of said compartments; a cooling plenum containing an evaporator, said plenum being disposed contiguous the other of said compartments and separated therefrom by a partition apertured to provide a passage for the circulation of air between said plenum and said other of said compartments, means forming a communicating passageway between said plenum and duct means; and air circulating means for selectively controlling the movement of refrigerated air through each of said passageways in response to individual temperature conditions existing in each of said compartments.

References Cited in the lile of this patent UNITED STATES PATENTS 2,180,974 Atchison Nov. 2l, 1939 2,285,945 Rundell June 9, 1942 2,481,616 Richard Sept. 13, 1949 2,866,323 Candor Dec. 30, 1958