US2167036A - Refrigerating apparatus - Google Patents

Description

July 25, 1939. R. E. BAKER REFRIGERATING APRARATUS Filed June ll, 1937 2 Sheets-Sheet l July 25, 1939. Rl E, BAKER 2,167,036

REFRIGERATING APPARATUS Fled June 1l, 1937 2 Sheets-Sheet 2 Patented July'ZS, 1939 I t UNITED STATES PATENT oFFIcE REFRIGERATIN G APPARATUS Ralph E. Baker, Detroit, Mich., assignorvto Nash- Kelvinator Corporation, Detroit, Mich., a corporation of Maryland Application June 11, 1937, Serial No. 147,750

4 10 Claims. (Cl. (i2-,116)

This invention relates to re'frigerating appa- Figure 7 is a fragmentary view of a modified ratus and more particularly to the so-called form of refrigerating apparatus embodying feahousehold type of refrigerators. tures of my invention;

One of the objects of my invention is to pro- Figure 8 is a view in cross section of a modified vide an improved refrigerator of the type whereform 'of the apparatus embodying features of my 5 in circulating air is refrigerated to the desired invention;

temperature for the proper preservation of foods Figure 9 is aview taken along line 9-9 of Figand also ice cubes and the like are frozen, and ure 8; and to have provisions for periodically defrosting the Figure 10 is a fragmentary view of a modified 10 cooling element' which refrigerates the circulatform of refrigerating apparatus embodying my l0 ing air Without in any manner disturbing the invention.

refrigeratlng effect of the system which is uti- It has always been a source of considerable lized for freezing purposes. f inconvenience to users of household refrigerators Another object of my invention is to provide and the like to periodically defrost the cooling l5 an improved refrigerating system including two unit of such refrigerators. The accumulation of 15 refrigerant evaporating elements which are so ice or frost upon the outer surface of the cooling arranged within a refrigerator cabinet that the unit is occasioned by the design of and the temone element is used lfor ice making purposes and perature at which the unitl operates. Moisture in the other for cooling circulating air withY the the air circulating through the food compartment ice making element being isolated from the ciris.condensed upon the surface of the cooling unit 20 culating air so ,as to avoid the possibility of exand freezes, forming a slowly increasing layer of tracting moisture from said circulating air, and ice which considerably reduces the efiiciency of to have provisions for temporarily discontinuing the cooling unit. vIn order to remove the frost the refrigeration in the air cooling evaporator so thus accumulated it has 'been the practice to dis- .that frost and ice may be melted therefrom while continue refrigeration to allow the cooling unit 25 at the same time the ice making element remains to warm up above the freezing point of water effective to freeze ice cubes and the like and to until it was again free of lts coating of ice. In retain same in a frozen condition while such deso doing, not only does the temperature of the frosting of the air cooling element takes place. food compartment rise but it is also no longer Another object of my invention is to provide possible to obtain ice cubes or frozen desserts or 30 for varying the effectiveness of the aforesaid air to retain those already frozen. If, however, the cooling refrigerant evaporating element to comtemperature of the ail cooling unit is vcontrolled pensate for any variations in the temperatures of independently of the freezing unit wherein cubes the environment air surrounding the refrigerator and desserts are frozen, there is no longer any 36 to thus tend to maintain substantiallyv constant need for the freezing compartment to be inop- 35 temperaturesthefood-storage compartment of erative since any fro'st collecting on the air coolthe refrigerator throughout variations and ing portion may be removed without interfering changes in temperatures of the environment air. with the freezing portion of the unit in the freez- In the drawings: ing compartment. t 4o Figure 1 is a fragmentary view of a refrigerator In accordance with my invention I provide a 40 embodying features of my invention; refrigerator wherein ice cubes and the like may Figure 2 is a view shown partly -diagrammatbe continuously frozen and retained in a frozen ically and partly in cross section of a refrigercondition even though the refrigerant evaporatating apparatus embodying features of my ining element which cools the circulating air in vention; the cabinet is being defrosted. This is accom- 45 Figure 3 is a view taken along the line 3--3 of plished by utilizing a heat absorber or cooling Figure 2; unit consisting of -two refrigerant evaporators, Figure 4 is a view taken along the line 4 4 one of which is used for freezing purposes and of Figure 2; the other for cooling the circulating air in the Figure 5 is an enlarged fragmentary View of a food storage compartment of the cabinet. The 50 portion of the refrigerator illustrated in Figure 1; two refrigerant evaporators are so connected that 1 Figure 6 is an enlarged view shown in cross the one used for cooling circulating air may be section of a valve mechanism used for controldefrosted without interfering withthe refrigeratling the flow of refrigerant in the apparatusV ing effect of the other or ice freezing evaporator.

5t shown in Figure 2; Thus the air cooling evaporator may be defrosted 55 r v u u Murnau. uvunn5 unav ucnigunucu. 1u general by the numeral 25. 'I'his cooling unit is operatively associated with a refrigerant condensing element 26v which, for example, may be disposed within the aforesaid machine compartment in the lower part of the cabinet.

'Ihe cooling unit 25 comprises, in general, a thin sheet metal casing 21 positioned near the upper part of the compartment 24 and substantially midway between the two side walls of th'e cabinet 2|. 'I'he casing 21 may be constructed of any suitable material such as stainless steel or any other thin sheet metal and if desired may be provided with a coating of vitreous enamel such as porcelain on its inner and outer walls. The casing 21 is of box-like formation and includes a front wall 28 provided with an opening 29 closed by a hinged door 30. Within the casing is disposed a heat absorber designated in general by the numeral 3|, which is utilized for cooling circulating air within the compartment 24 and is also used for freezing ice cubes, desserts and thelike.

The heat absorber 3| of the refrigerating apparatus, shown to best advantage in Figures 2, 3 and 4, comprises in general, a tank 34 adapted to contain a quantity of liquid refrigerant and refrigerant evaporators 36 and 40 which are in open communication with the tank by means of a common conduit 42 with the lower end of the tank 34. Evaporators 36 are two similar refrigerant expansion coils which have a juncture point 44 from which they extend upward along the sides of the casing 21 with which they are joined in good thermal contact, either through welding or soldering. If desired, instead of coils 36, these two evaporators may simply form lpart of the casing 21 vby using a double wall of sheet metal extending from top to bottom of the casing, refrigerant being contained in the space between the two walls. Evaporator 40 also extending upward from the `juncture point 44 consists oi' shelves 46 joined by conduits 48. These shelves which are adapted to support ice pans 1 are simply two sheets of metal welded or soldered together with sumcient space between to'permit liquid refrigerant to circulate therethrough. Evaporators 36 reunite at a valve 58 and when the' valve 50 is open the evaporators are -both in open communication with the top of the tank 84 through a conduit 52. Evaporator 48, on the other hand. is always in open communication at changes in temperature in the tank 34 in the well known manner. I

During periods when the float valve 64 is open, liquid refrigerant passes through the conduit 56 whence it is injected into the inlet end of the conduit 42 by means of an injector or nozzle 80. Since the tank 34 is in open communication with the conduit 42 and normally with the upper ends of the evaporators 36 and 4B, and conduit 42 is in open communication with lower ends of the same evaporators, the level of liquid refrigerant within the expansion conduits 36 and 40 will normally be substantially the same as in the tank 34.

From the,foregoing, it will be apparent that the large volume of liquid refrigerant in the tank will compel evaporated refrigerant in the expansion conduits to pass through the outlet ends of same, namely 52 and 54, and into the tank due to the resistance offered by said large body of liquid. Under some circumstances, the evaporation of refrigerant will lbe so great in the expansion conduits 36 as to pick up liquid refrigerant and deliver it to the tank, whence it descendsto be recirculated.

In order to initiate the ebullition and to promote the circulation of liquid refrigerant through the expansion conduits 36 and 40, the injector has been provided. This prevents the superheating of liquid refrigerant in the expansion conduits and tends to maintain uniform temperatures throughout the various parts of each of the expansion conduits or evaporators. 'I'he injector is formed'by tapering the outlet end of the conduit 56. The tapered or restricted" end 80 is disposed part way into a fitting 62 to which the conduit `42 is connected. The conduit 42 vis secured tothe tank, preferably by welding. The injector is adapted to Ainject expanded refrigerant into the conduit 42. During periods when the float valve 64 is open, the refrigerant leaving the high pressure side of the system and entering the low pressure side aisance through the orificed valve seat 66 becomes expanded (partly gas and partly liquid). The expanded refrigerant is. received in the conduit 42 at pressures somewhatl greater than those normally existing in the expansion conduits. This high pressure expanded refrigerant leaves the injector and enters the liquid refrigerant in the conduit 42 where the pressure is somewhat lower. Consequently, the injector provides a means of positively circulating liquid refrigerant in the various refrigerant evaporators. It will also be noted thatv the gaseous part of the injected refrigerant immediately initiates the ebullition of refrigerant in the expansion conduits upon its admission thereto. Also the gaseous part of the injected refrigerant, in addition to starting the ebullition in the expansion conduits, promotes ebullition throughout its passage therethrough.

By positively circulating, initiating and promoting ebullition and the circulation of refrigerant, both liquid and gaseous, in the refrigerant evaporators, the oil pumped thereinto by the compressor is readily returned to the compressor through the vapor conduit 58, by reason of its entrainment with the evaporated refrigerant.

In the case of refrigerators utilizing a single cooling unit to cool a food compartment and to maintain ice cubes and desserts in a frozen condition, the users are frequently called upon to stop the compressor in order to allow the frost which accumulates on the surface of the cooling unit to melt. During this defrosting period the ice cubes and frozen desserts can no longer be maintained as such, occasioning much annoyance and inconvenience to.the user of the refrigerator. To avoid this condition, itV has been found desirable and also economical to install in the low side of a refrigerating apparatus more than one expansion coil, said coils being operable, if desired, at different temperatures.

In accordance with my invention, I provide for maintaining the evaporators 36 which may be considered as a single evaporator, and the shelf evaporator 40, either at the same temperature or at different temperatures, depending upon conditions within the refrigerator vand upon the type of refrigeration required. This is accomplished by merely providing the manually operable valve ing into the top of the tank. This valve servesv to control the amount of refrigerant which is circulated through the evaporators 36. Preferably, valve 50 is of the packless type. The ow of refrigerant through the expansion conduits 36 may nbe retarded to a predetermined amount or may be entirely shut off by means of this valve. When the flow of refrigerant is entirelystopped through said conduits no refrigeration will take place in the respective conduits. When the valve is operated to retard the flow of refrigerant through the evaporators 36, the refrigerating effect of said evaporators will be reduced and will be less than that of the evaporator which is provided with an unrestricted outle passage, namely, the shelf evaporator 40. This valve is not of the pressure responsive type but is of the type which positively shuts oil. the flow of refrigerant through an expansion coil or permits a predetermined amount to flow through said coil without variation except when manually adjusted.

From the foregoing, it will readily be apparent that the retarding of the flow of refrigerant through some of the refrigerant evaporators will decrease the amount of liquid refrigerant as well as the amount of gaseous refrigerant which is being circulated through an evaporator. By slowing up the circulation of refrigerant through the evaporators 36 and keeping the liquid level 5 down, the rate of heat transfer has been lessened, which effects the heat transfer characteristics of the respective evaporators to maintain as a result a higher temperature in said evaporators than in the evaporator 40 in which the flow of lo refrigerant is unrestricted. It will also be noted that the refrigerant supply conduit 42 is in open communication with the inlet ends of each of the refrigerant expansion coils, and for this reason the pressures in the various expansion coils l will normally be substantially equal. Furthermore, it will be noted that the temperatures of the various evaporators may be controlled by simply manipulating the valve 50.

During the on-phase of the refrigerating cycle, m the condensing element withdraws evaporated refrigerant from the gaseous refrigerant space in the tank 34 intowhich the evaporators 36 and 40 expel refrigerant vapor produced within their own respective conduits. During this time it has 25 been found that there is a slight pressure dif)- ference equal to onlyv a few inches of liquid refrigerant pressure on opposite sides of the valve 50 when it is partly closed. This slight pressure difference causes a slight amount of liquid re- 30 frigerant inthe expansion conduits 36- to be forced back into the conduit 42 to the tank 34. During the off phase of the refrigerating cycle and when the valve is but partly closed, the pressures on opposite sides of the valve are substan- 'as tially, if not entirely, equal. Under these circum- `stances the level of liquid refrigerant in each of the expansion conduits and the tank 34 is the same. Preferably the level of liquid in tank 34 is above conduit 54 butbelow the outlet of cono duit 52. The size of tank 34 is such that it will hold all of the liquid backed up from evaporators 36. A'

In order to arrange for ready access to the valve 50, I have provided a rod 10 (Fig. 3) attached to o45 the valve 50 and extended through the front of the casing 21 at 86. A knob or handle 88 is fastened on the end of rod 10 outside the casing 21 to facilitate manipulation of said valve. This places the system in readiness for the selective 50 control of temperatures. s

During normal operation of the refrigerating apparatus,v the coils 36 along the inside of the casing 21 which serve to cool the air circulating through the foodcompartment 24 and the shelf 55 evaporator 40 which is adapted to maintain ice cubes and desserts in a frozen condition are kept at substantially the same temperature. In other words valve 50 is nearly or completely open.

Liquid refrigerant flowing through the two ex- 60 pansion conduits 36 at substantially the same pressure not only serve to remove heat from the air contacting the outer surface of the metal casing 21 but also acts as a protective barrier to the shelf evaporator y4I) in that the heat of the food 65 within, the casing 21 at a predetermined low tem- 70 perature. The casing 21 also prevents contact of Y circulating air with evaporator 40 so as to prevent the extraction of moisture from said'air.

' However; during periods of normal opration of' the refrigerating apparatus, frost ordinarily col- 75 the contents of pans placed upon the shelves 46 in a frozen condition results during the period of defrostlng vthe outer shell 21. v

'I'he collection of frost upon the outer surfaces o'f a refrigerant evaporator has hitherto been considered a disadvantage over which little or no control could be exercised. By means of my invention, however, it becomes possible not only to vary the amount of frost collected during normal operation of the refrigerating unit, but also to prevent its formation entirely. If the surfaces of the metal casing 21 be greatly increased and the coils 36 lining the inside of same be constructed in such a fashion as to permit only very little amount of refrigerant to circulate therethrough, no frost at all will collect or, if any, such a small amount that it will -melt between cycles of operation of the refrigerating unit. On the other hand, it may be desired to maintain the outer evaporators 36 below freezing at all times except when defrosting in which case, the surface of the shell 21 would be reduced and the quantity of liquid refrigerant circulating'through said evaporators increased. Thus it is apparent that great latitude in varying the conditions within the food compartment is afforded without laltering the effectiveness of the'shelf evaporator 40 in maintaining continuously a predetermined freezing temperature.

In Figure 6 of the drawings there is shown a form of valve structure 50 suitable for use in connection with refrigerating systems hereinbefore described. The valve structure 50 comprises, in

general, a casing 90 having a bore 9| which serves as a chamber for uid. The casing is also t provided with two inlets, 92 and 93, and an outlet proper 95.

94 for the passage of fluid to and from the chamber 9|.. Within the chamber 9| there is disposed for movement a valve proper 95 which cooperates with a valve seat 96 to control the passage of fluid through the chamber 9|. To the valve proper there isl joined, preferably integrally, a push rod or actuator 91 for actuating the valve In order to providey a packless valve and one which is sealed against leakage of iluid from the chamber 9 I I have provided flexible means which permits operation of the valve proper from the exterior of the chamber 9| but which hermetically seals said chamber against leakage. This flexible means constitutes a flexible bellows 98. This bellows is sealed on one end thereof to a shoulder 99 of an annularl sleeve |00, which is preferably press fitted into bore 9| to prevent the escape of fluid between the outer wall of sleevev| and bore 9|. The opposite end of bellows 98 is sealed to an annular ring |0I, which is preferably welded or soldered to the push rod au applica um u1 uc: ou au uululul.' lluulutlr or ring |00 which is secured to push rod 91 by key |09 immediately above ring |0|. When the valve is in a closed position, thespring is under compression so that the moving of threaded member |05 upwardly permits the valve and push rod to follow such upward movement to open the valve to the extent desired.

When the'valve is in an open position, the turn- 25 ing of the threaded member |05 in a direction which causes it to move downwardly will cause the valve proper to move downwardly toward closing position, by reason of the fact that the end of said member is in engagement with the push rod 91 at all times.

Although the valve structure above described is a preferred one, it is to be understood that other valves, well-known in the art, for example, valves of the electromagnetic type, may serve equally as well for certain purposes as the one herein described.

In Figure 7 there is shown a modification of the refrigerating apparatus above described. The thermostat bulb 19, instead of being attached to the side of the tank 34 is placed in good thermal contact with the outside of casing 21, so that the `operation of the compressor is controlled in response to changes in temperature of the metal shell 21. This may be desirable under certain conditions` of operation.

In Figures 8 and 9 there is shown another modied form of refrigerating apparatus which comprises, in general, an insulated cabinet 4 having a compartment |I6 in the top of the 50 cabinet, wherein a temperature below the freezing point of water may be maintained, and a compartment ||8 wherein food is adapted to be stored. Within the compartment 6 there is disposed a tank |20, corresponding to tank 34 55 in Figures 2, 3, and 4, a shelf evaporator |22, which serves the same purpose as Vexpansion con-- duit 40. In compartment ||8 there is disposed an expansion conduit |24 in good vthermal con. tact with a metal sheet |26. corresponds to the evaporators 36 of Figures 2 and 4.

The structure of the above modified refrigerating apparatus is the same as that of the apparatus previously described; it differs only in the location of parts within the cabinet. Liquid refrigerant is supplied tothe evaporators |22 and |24, and tank |20 through a'supply line |28 which terminatesin an injector |30. The injector is in open communication with both evaporators and with/the interior of tank |20. Evaporator |24 communicates with the top of theV tank |20 through a conduit |30; shelf evaporator 22 is always in open communication with the top of'V tank |20 through conduit |32. Refrigerant va- 75 Jub' 25, 1939' R. c. BENNER Er Al. 2,167,037

ABRAS IVE SUPPORTING PAD Filed Deo. 3o, '1935 INVENTOR. RAYMOND QBENNER CHARLES E wooDDELL CHARLES sfNELaoN ATTORNEY.

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