US2944410A - Refrigerating apparatus - Google Patents

Description

in-s1 July 12, 1960 Filed Oct. 6, 1955 L. .1. MANN ETAL 2,944,410

REFRIGERATING APPARATUS 3 Sheets-Sheet 1 z J'WW 60/76! a? a; 2222/? lu kjykirm ii THEIR ATTORNE) July 12, 1960 L. J. MANN ETAL 2,944,410

REFRIGERATING APPARATUS Filed om. e, 1955 3 Sheets-Sheet 2 ggy Z INVENTORS HE/l? lqrromvsv July 12, 1960 L. J. MANN ETAL REFRIGERATING APPARATUS Filed 001.- .6, 1955 3 Sheets-Sheet 5 THE/R, A'rromvsr United sass 2 44,410 REFRIGERATJNG APPARATUS Leonard J. Mann, John Murphy, and Clifford H.

Wurt z, Dayton, Ohio, assignors to General Motors Corporation, Detroit, Mi a corporation of Dela.- ware a v Fi O 6, v N9- 538 92 3 Claims. 7 c1. 62-;86)

lems in view ofthejfact that the refrigeration oa each compartment fluctuates unevenly. r

It is an object of this invention to providea simple and inexpensive control which" makes it"possi'hle to maintain the temperature in each ofthe compartments; sub- 'stanti'ally constant'at all times irrespective of: theffluctuations in refrigeration requirements in the different food compartments. I l

More particularly, it is anpbject of this invention to provide a refrigerating system in which a fan circulates air over the second of two series connected evaporators and in which the refrigerant liquefying apparatus is cycled by a thermostat located in" contact with this, second evap; orator and; the fan isseparately cycled in response to changes in the rem erame of the air'leaving second evaporator. V a t It is another object of this invention to provide anirn;

proved type of automaticdefrosting arrangement in a refrigerator of the type using forced air circu ation over a portion of theevaporator.

Further objects and advantages ofthe present invention will be apparent from the;followingdescriptionr ifi rence being had to the cc mpany n r win s. preferred form of the present) invention is; clearly shown. Inthe drawings:

Figure l is a perspective view showing a preferred embodiment of the invention; I

Figure 2 is a vertical sectional view showing the arrangement of the evaporatorsrelative to the food storage compartmentsand Figure 3 is a fragmentary sectional view taken substantially on line 3-3 of Fig. 2, showing the one evapo-. rator in the air fine and schematically showingtheirefrigerant circuit.

Referring now to .the drawing, wherein av preferred em.- bodiment of the inventionhas been. shown,..reference numeral 10 generally designates a. household refrigerator having a motor-compressor compartment 12,.a.fr'ozen food storage compartment 14, amainfood storage com-. partment 16 for storingunfrozen foods. anduashydrator 1'8 pivotally supported onjthe mainrefrigerator door20. The refrigerator comprises. the. usual sheetv metal outer shell 22. which serves to.supportapair,ofinner liner ele ments, and 26- which form the frozen: food. compartment and the unfrozen, foodstorage compartment, respec-. tiyely. Suitable insulation: 28 iswprovided: betweenwtheouter shell 22 and theinner liners inzaccordan'cewith standard practice. v I V V 7 The main door-20 isprovidedwith one or more shelves wherein a,

;1iitent d my a l-asa 2 V I 3.0 foruse in storing such articles as eggs and condiments and also serves as a support for the hydrator 18.

For a more detailed description of the construction of the hydrator, reference is hereby made to our copending application, Ser. No. 418,668, filed March 25, 1954, now Patent Number 2,859,595, which shows an earlier version of the refrigerator disclosed herein. 3

The refrigerating system which is used for cooling the food stored in the compartments 14, 16 and 18 consists of the usual motor-compressor unit 50 which is preferably of the hermetically sealed rotary type which is now very well known and needs no further description. The compressed refrigerant leaving the. compressor 50 flows into the condenser 52 from whence the liquid refrigerant flows through -a conventional fixed restrictor type Of'PFCSSUIG reducing device 54. Insofar as certainaspects ofthis invention are concerned .any type of pressure: reducing means may be used such as an automatic expansion valve or a thermostatic expansion valve.

-In the preferred embodiment of the invention, a fixed restrictor is used and servesto convey liquid refrigerant into a first primary evaporator 56 which is incorporated inthe liner 24 of the, frozen food compartment 14 After the, evaporatorv5 6 has been filled, with. liquid refrigerant the surplus refrigerant flows through an unrestricted passage, 58 into. a second primary evaporator tiliwhich. is

mounted in an air 1111610 at the; back of the compartment 1'6 and serves to cool the main food storage compartment 16 in a manner to be eXplainedrnorefully hereinafter;

The second evaporatorotlconsists of a rollbonded; plate which has been manufactured by the process disclosedin US. Patent Nos. 2,662,273 and 2,712,736. The liquid refrigerant leavingthe first evaporator 56 enters theevaporator 60.. through the line 58 which leadsto a wafiie+ plate type of' accumulator and primary evaporator passage 61-. The refrigerant leavingthe passage 61 flowsthrough 'apassage-63into the bottom-ofiasecond wafiie=plate type ofaccuinulator .and refrigemnt passage 65 which' is arranged, as shown. The outlet-from-the'passage 65: is connected to a plate: typeaccumulator 67 located in the return line 62 v which leads to the inlet of the motorcompressor. unit 50.; Thewaiflerpla-te -type of accumulator passages 61 and. 65 serve the dual: purpose of storing sur plusrefrigerantand as disengagingpassages which pre vent the. vaporized refrigerant from sweeping slugs of liquid. refrigerant into the suction line 62.-

Invi'ew of the fact that the capacity of the primaryevaporators 56 and 60,- will varyfrom one refrigerator to another due to the inability or-impracticabilityofmanu factoring; all evaporators exactly alike; some means. must be provided for compensating for such variations: F'urtlierrnore; changes: in ambient temperatures and changesinrefrigerant loads will'cause rather-wide variaa tionsin the quantity; of liquid refrigerantin;the-evapo rators 56 and 60-with-theresult-that in at'lea'stzsome' of: the. refrigerators there will be a tendency-'at timesfor liquidrefrigerant to enter thersuction line 621 BYrVlI'tllQ of the platetype accumulator 67 being arranged: in di-rect thermal exchange relationship;- with v theend: walhof the frozen food compartment liner- 24: this surplus liquid refrigerant will be vaporized in-the)- aceumul'ator67 so as: to: usefully refrigerate the frozen; food-compartment 1'4? At-snchtimes; when no liquidf refrigerant spills over into the suction line 62 the plate type accumulator 67*f serve 'toremove super heats-from the relatively warm refrigerahhvapor leaving the 'plate' ty'pe evaporator 60.

The "evaporator; 60' ismounted in the air fine 711% ar-f an outlet 74 adjacent the upper portion of the compartment 16. A fan 76 is used for forcefully circulating air through the flue so as to cool the air and then discharge it forwardly adjacent the upper portion of the comparte ment 16. The air then flows downwardly in thermal exchange relationship with the food stored on the door shelves and part of the air flows between the hydrator 18 and the door and some of the air short-circuits down through the main portion of the food storage compartment on its way to the return air inlet 72. By virtue of this forced air circulation arrangement and by virtue of the fact that the food shelves and hydrator are constructed so as to facilitate the circulation of air, it is obvious that no pockets of stagnant air will form during normal operation of the apparatus. The fan 76 is offset from the bottom of the evaporator 60 as as to be out of the path of defrost water draining from the evaporator 60, as best shown in Fig. 3. The lower end of the flue and the blower extend into the compartment 16, as best shown in Fig. 2, so as to allow space for insulation'between the rear of the blower assembly and the outer shell 22.

The control for the motor-compressor unit consists of a thermostatic bulb 80 mounted on the upper end of the evaporator 60, as shown. This'bulb operates a switch 82 (Fig. 3) arranged in the circuit 83 leading to the motor-compressor unit 50 so as to start and stop the unit50 in accordance with temperatures of the evaporator' 60. The switch 82 is preferably set to stop the operation of the motor-compressor unit when the temperature of the plate '60 drops down to -15 F. and restarts the compressor when the temperature at the bulb 80 reaches a value of somewhere between 34 and 36 F. By virtue of this type of control and the refrigerant circuit arrangement shown, together with the proportions of the evaporators to the size of the compartment to be cooled, it is possible to maintain the desired temperature differential between the frozen food compartment 14 and the unfrozen food compartment 16 at all times and to cause the evaporator 60 to defrost itself during each Off cycle without melting any of the frozen foods. The switch 82 includes the usual cold control adjustment 84 which enables one to adjust the, setting of the switch 82 so as to maintain either colder or warmer temperatures in the frozen food compartment 14.

The fan 76 is adapted to be cycled by means of a thermostat 85 located in the path of the air leaving the upper end of the flue 70. This thermostat is shielded by a plastic plate 87 which prevents the outgoing air from directly contacting the thermostat 85. This plastic plate 87 serves to retard the response of the thermostat 85 in a manner to prevent short-cycling of the fan 76. The thermostat 85 controls a switch 89 which is arranged in the circuit 91 of the fan 76. The switch 89 is preferably set to close the circuit to the fan 76 whenever the temperature at the thermostat bulb 85 is above 30 and is adapted to maintain the circuit closed until the temperature at the bulb 85 drops to a value of approximately 23 at which time the circuit to the fan 76 is opened. It has been found that the construction and arrangement described hereinabove makes it possible to maintain the air temperature in the compartment 16 at a very constant value of approximately 36 irrespective of changes in the outside air temperature and changes in refrigeration requirements resulting from frequent opening of the door 20 or resulting from variations in the amount and temperature of the food placed in the refrigerator.

The frozen food compartment 14 is provided with an inner door 90 which prevents the free circulation of air between the compartments 14 and 16 and which prevents air from entering the frozen food compartment 14 each time the door 20 is opened. The compartment 14 is provided with the usual ice-tray shelves 92 which serve to support ice trays 94. The evaporator 56 is large enough in proportion to the size of the'compartment 14 so as to maintain the temperature in the compartment 14 at or near 0 F. depending upon the setting of the cold control 84, with the result that water may be frozen in the trays as needed.

Since the evaporator '56 is the first to receive any liquid refrigerant, it is obvious that the frozen food com partment will be maintained properly refrigerated at all times before any of the surplus refrigerant will flow upwardly into the second evaporator 60. It is also obvious that when the compressor stops operating, the refrigerant in the evaporator can drain down into the first evaporator portion 56 so as to continue refrigerating the frozen food compartment after the last of the refrigerant has been vaporized in the evaporator 60.

During the Off cycle of the motor-compressor unit 50, when the last of the refrigerant in the evaporator 60 has been vaporized, the air flowing over the evaporator will quickly raise the temperature of the evaporator above the freezing point of the frost on the evaporator so as to thereby cause defrosting of the same. The defrost water drains from the bottom of the flue 70 through a slot 95 into the bottom portion of the food compartment 16 from whence it enters a drain 100 which conveys the condensate water down into a pan 102 arranged in thermal exchange relationship with the relatively hot condenser 52 so as to cause evaporization of the defrost water. The drain 100 includes a drain tube 104 which by-passes the freezer compartment 14 and the insulation surrounding the compartment 14.

While the form of embodiment of the invention as hereindisclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. In a refrigerator, a cabinet having a first compartment for storage of frozen foods and a second compartment for the storage of unfrozen foods, a first evaporator arranged in thermal exchange relationship with said first compartment, a second evaporator for cooling air for said second compartment, refrigerant liquefying means, refrigerantfiow means for supplying liquid refrigerant from said refrigerant liquefying means to said first and second evaporators in series, said refrigerant flow means including pressure reducing means adjacent the inlet of said first evaporator, said second evaporator being connected to the outlet of said first evaporator so as to receive the overflow refrigerant from said first evaporator, means responsive to the temperature of one portion of said second evaporator for controlling the operation of said refrigerant liquefying means, fan means forcefully circulating air from said second compartment into thermal exchange relationship with said second evaporator, means responsive to the temperature of the air leaving said second evaporator for starting and stopping the operation of said fan, said last named means including a temperature sensing bulb and means for shielding said bulb from direct contact with the air discharged by said fan means.

2. In a refrigerator, a cabinet having a first compartment for storage of frozen foods and a second compartment for the storage of unfrozen foods, a first evaporator arranged in thermal exchange relationship with said first compartment, a second evaporator for cooling said second compartment, a compressor, a condenser, refrigerant flow means connecting said evaporators, compressor, and condenser in series flow relationship, pressure reducing means in said refrigerant flow'means between said condenser and said first evaporator, said second evaporator being directly connected to the outlet of said first evaporator was to receive the overflow refrigerant from said first evaporator, means forming an air flue adjacent one wall of said second compartment, said second evaporator being mounted in said air flue, fan means forcefully circulating air from said second compartment throughrsaid air. flue in thermal exchange relationship with said second evaporator, and means responsive to the temperature of the air at the outlet of said air flue for starting and stopping said fan means.

3. In a refrigerator, a cabinet having a first compartment for storage of frozen foods and a second compartment for the storage of unfrozen foods, a first evaporator arranged in thermal exchange relationship with said first compartment, a compressor, a condenser, refrigerant flow means connecting said evaporators, compressor, and condenser in series flow relationship, pressure reducing means in said refrigerant flow means between said condenser and said first evaporator, said second evaporator being directly connected to the outlet of said first evaporator so as to receive the overflow refrigerant from said first evaporator, means forming an air flue adjacent one Wall of said second compartment, said second evaporator being mounted in said air flue, fan means forcefully circulating air from said second compartment through said air flue in thermal exchange relationship with said second 6 stopping the operation of said compressor.

References Cited in the file of this patent UNITED STATES PATENTS 10 2,065,604 Miller Dec. 29, 19 36 2,095,010 Phillip Oct. 5, 1937 2,117,104 Rorison May 10, 1938 2,133,956 Buchanan Oct. 25, 1938 2,418,150 Adriansen et al. Apr. 1, 1947 15 2,589,551 Iwashita Mar. 18, 1952 2,594,036 Knapp Apr. 22, 1952 2,692,482 Shoemaker Oct. 26, 1954 2,723,533 Mann Nov. 15, 1955 2,807,149 Williams Sept. 24, 1957 5 6 1 evaporator, means responsive to the temperature of the air at the outlet of said air flue for starting and stopping said fan means, and means responsive to the temperature of a portion of said second evaporator for starting and

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