US2645094A - Refrigeration apparatus - Google Patents

Description

July 14, 1953 G. s. M CLOY REFRIGERATION APPARATUS 2 Sheets-Sheet 1 Filed March 1, 1950 INVENTOR GRAHAM S. MG LOY ATTORNEY July 14, 1953 G. s. MCCLOY 2,645,094

REFRIGERATION APPARATUS Filed March 1, 1950 2 Sheets-Sheet 2 F IG .3. WITNESSES: INVENTOR I GRAHAM s. MCCLOY I ATTORNEY Patented July 14, 1953 UNITED STATES PATENT OFFICE REFRIGERATION APPARATUS Graham S. McCloy, Springfield, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 1, 1950, Serial No. 146,960

7 Claims.

This invention relates to refrigerating apparatus and more especially to temperature regulating devices for refrigerators equipped with rapid defrosting means.

The temperature regulating device of refrigerators preferably comprises a temperature-responsive element located in the refrigerated chamber and connected to the cooling unit by a metallic strip of limited heat-conducting capacity. This construction provides that the temperatureresponsive element is responsive to the temperature of the air in the chamber as well as to the temperature of the cooling unit. The latter is necessary to prevent over-running of the refrigerant-supplying apparatus. By over-running is meant the cooling of the cooling'unit to a very low temperature merely because of the time lag between the cooling of the evaporator and the resulting cooling of the air in the cabinet.

In a refrigerator in which the cooling unit is rapidly defrosted such as by conducting warm refrigerant liquid through its refrigerating passages, a temperature-sensitive element so mounted defrosts more slowly than the evaporator and may not defrost completely during the defrosting operation. This is caused by the fact that the warm refrigerant liquid is only in limited heattransfer relationship with the temperature-sensitive element. If the temperature-sensitive element is not completely defrosted at the end of an automatically controlled defrosting operation, the frost thereon will be still thicker at the end of the next automatic defrosting operation and the thickness of this frost will gradually increase until it interferes with the proper functioning of the refrigerator.

Accordingly, it is an object of this invention to provide thermostatic means for controlling the temperature of a refrigerator which means is responsive to the temperature of the air in the refrigerator and which means is positively defrosted during the defrosting of the cooling unit.

It is a further object of the invention to provide effective means for controlling the temperature of a refrigerator.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. l is a somewhat schematic drawing of a vertical sectional view of a refrigerator embodying the thermostatic control of this invention;

Fig. 2 is a vertical sectional view'of the refrigerant liquid storage chamber of the refrigerator;

Fig. 3 is a partial vertical sectional view similar to the Fig. 1 but showing a modification of the invention; and

Fig. 4 is similar to Fig. 3'but shows another modification of the invention.

Referring to the drawings for a description of the invention, the reference numeral l0 designates a refrigerator cabinet having a food storage chamber l2 in the upper portion thereof and a machine compartment l4 below the food storage chamber. The food storagechamber I2 is surrounded by thermal insulation l6. A sealed casing IS in the machine compartment [4 contains a compressor and an electric motor 22 for driving the same. An inlet port 24 of the compressor Z0 communicates with the interior of the sealed casing l8. A pressure conduit-26 leads the refrigerant vapor compressed by the compressor 20 to an air-cooled condenser 28. A capillary tube 30 conducts the refrigerant liquid formed in the condenser 28 to a larger tube 32 located in the thermal insulation I6 of the cabinet Ill. The refrigerant liquid vaporizes in part in the tube 32 and then flows into an accumulator 34 forming a part of the rapid defrosting device of the refrigerator.

A second tube 36 communicates at one end 33 with a lower portion of the accumulator 34, then rises upwardly above the accumulator 34 and returns downwardly through the accumulator 34 and at its other end 40 connects with an evaporator 42. A small opening 44 is provided in the tube and communicates with an upper portion of the accumulator 34. During the refrigerating operation of the apparatus, the accumulator 34 is filled with refrigerant liquid to the level of the hole 44, and the refrigerant liquid and vapor flows through this hole 44 and through the lower portion of the tube 36 into the evaporator 42.

A suction tube 46 conducts the vaporized refrigerant from the evaporator 42 downwardly to the casing l8. The suction tube 46 has a portion 48 in heat-transfer relationship with a portion 50 of the capillary tube 30 and a lower portion 52 in heat-transfer relationship with the pressure conduit '26.

The thermostatic control of this invention comprises a blind metal tube 55 which communicates with the accumulator 34 and extends upwardly therefrom.

The electric motor 22 receives its power from the lines 58 through the leads 60. A thermostatic switch 62 is located in one of the leads and is controlled by a temperature-sensitive bulb 64 located at the upperend of the blind tube '56.

The bulb 64 contains a volatile fluid, the vapor pressure of which is transmitted to the thermostat 62 through a tube 66. When the temperature of the bulb 64 and consequently the vapor pressure of the liquid therein exceeds a certain limit, the switch of the thermostat 62 is closed and when the temperature of the bulb 64 drops to a lower limit the switch in the thermostat 62 is opened so that the refrigerating apparatus is actuated to hold the temperature of the bulb 64 between two fixed temperature limits. Both of these limits are far below the freezing point of water so that the evaporator, the tube, and the bulb 64 accumulate a coating of frost.

A heater 68 is located adjacent the tube 32 to heat the same and is controlled by a switch located in a controller 10. Leads 12 connect the heater 68 and the switch of the controller in series with leads 60. The controller 10 is of the type described in the patent application, Serial No. 143,788, filed February 11, 1950, by the inventor of this invention, now Patent No. 2,595,967, granted May 6, 1952, and comprises a counting device which is actuated through a plunger 14 to close the switch of the controller 10 when the door 15 has been opened and closed a certain number of times, such as sixty times. The switch of the controller 10 is again opened by a thermostat comprising a tube 16 and a temperatureresponsive bulb 18 located on the evaporator 42. When the evaporator 42 attains a temperature of above freezing the vapor pressure of a volatile liquid in the bulb I8 acts through the tube 16 to open the switch in the controller 10.

The defrosting action of this refrigerator is described and claimed in Patent No. 2,459,173, issued January 18, 1949, to the inventor of this invention and functions as follows: when the door of the refrigerator has been opened and closed the required number of times, the switch in the controller 70 is closed and when the switch in the thermostat 62 also closes, the heater 68 will be energized. When the heater 68 is energized, some of the refrigerant liquid in the tube 32 is vaporized so that an abnormal quantity of the refrigerant vapor enters the accumulator 34. This vapor is too large in volume to flow through the opening 44 in the tube 36 at the prevailing pressure. Consequently the pressure in the accumulator 34 rises until the refrigerant liquid is forced from the accumulator 34 through the end 38 of the tube 36. This refrigerant liquid is warmed by the warm vapor generated in the tube 32 by the heater 68.

The added refrigerant liquid transferred to the evaporator 42 from the accumulator 34 floods the evaporator 42 and runs downwardly through the suction tube 46 and through the portion 52 thereof which is in heat-exchange relationship with the pressure conduit 26. The liquid refrigerant is vaporized completely in the portion 52 of the suction conduit 46 by the heated vapor in the pressure conduit 25. This raises the suction pressure in the apparatus so that no further vaporization occurs in the evaporator 42 and so that the latter is defrosted by the warm refrigerant issuing from the accumulator 34.

Operation suction pressure as the evaporator 42 and cools the refrigerant liquid flowing therethrough by vaporizing a portion of this liquid.

During the refrigeration of the food storage chamber 12, the upper end of the blind tube 56 and the temperature-sensitive bulb 64 is warmer than the accumulator 34 because the tube 56 and the bulb 64 extend into the warmer air of the food storage chamber l2, The major portion of the heat-transfer from the bulb 64 to the accumulator 34 takes place only by conduction along the metal wall of the tube 56, since the vapor in the tube 56 cannot condense and hence does not circulate in the tube 56.

During the defrosting operation, the accumulator 34 is warmed by the warm refrigerant vapor entering it from that portion of the tube 56 which is in contact with the heater 68. This warm vapor entering the accumulator 34 also enters the tube 56, and since its temperature is higher than that of the tube 56 it will condense and the resulting condensate run down into the accumulator 34. The tube 56 will thus be warmed at substantially the same rate as the accumulator 34. The accumulator 34, furthermore, is warmer than the main evaporator 42 because it receives the warm refrigerant directly from the tube 32 and is the first portion of the evaporator system of the refrigerator which is defrosted. The tube 56 and the bulb 64, therefore, will be thoroughly defrosted.

Modifications Fig. 3 shows a modification of the invention in which a blind tube 80, similar to the blind tube 56, is secured to and communicates with the header 82 of the evaporator 42. In this figure, the elements which are similar to the elements of the previously described modification are provided with the same reference numerals, respectively. The defrosting action of the tube 85 is similar to that tube 56 but is somewhat slower because the tube is farther removed from the heater 68. The blind tube 80 can also communicate with a portion of the evaporator 42 which contains refrigerant liquid since this liquid would not enter the blind tube 80 because of the higher temperature of the latter.

Fig. 4 shows a further modification of the invention. In this modification a tube 84, closed at both ends, is employed. The tube 84 contains a small quantity of a volatile liquid and the vapor of this liquid is quiescent during the refrigeration operation of the apparatus but becomes active to warm the bulb 64 when the evaporator 42 tends to become warmer than the bulb 64 in the same manner as previously described.

It will be apparent from the above that this invention provides a mounting for the thermostatic control of a refrigerator which mounting provides a response to the temperature of the air in the refrigerated cabinet and also insures positive defrosting of the control when the cooling unit of the refrigerator is defrosted.

While I have shown the invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What I claim is:

1. In a refrigerator comprising a chamber and refrigerating apparatus, said apparatus comprising a low pressure side including a cooling unit for cooling said chamber and means for periodically defrosting said cooling unit, said means ineluding an accumulator of refrigerant liquid, said apparatus also including a high pressure side .1 or condensing the refrigerant vapor produced in said low pressure side, a pump for transferring refrigerant vapor from the low pressure side to the high pressure side, a temperature-responsive element for controlling said pump, said element being respbnsive to the temperature of the air in said chamber, and a tubular heat-conducting member having upper and lower ends, the upper end of said member being closed and arranged in heat-transfer relationship with said element and the lower end thereof communicating with said accumulator, the construction and arrangement of said member being such that its conductivity is relatively low when said accumulator is colder than said element and relatively high when accumulator is warmer than said element.

2. In a refrigerator comprising a chamber, evaporator for cooling said chamber, said evaporator having a passage, operating means for supplying refrigerant liquid to said passage and for withdrawing refrigerant vapor therefrom, a tu bular member formed of heat-conducting material and closed at one end, said member having an upper and a lower portion, the lower portion of 7 said member communicating with said passage and lying in heat-conducting relationship with said evaporator, the upper portion of said member being exposed to the air in said chamber, a thermostat including a temperature-responsive element, said element lying in heat-transfer relationship with the upper portion of said member, said thermostat controlling said operating means to activate the same when the temperature of said temperature-responsive element rises to above a certain value and to inactivate said operating means when said temperature drops to acertain value below 32 F. and heating means for warming said evaporator to above 32 F. to melt frost thereon.

3. The refrigerator defined in claim 2 wherein said heating means comprises means for so altering the action of said operating means that it supplies to and withdraws refrigerant liquid at a temperature of above 32 F. from said passage.

4. In a refrigerator comprising a chamber, an evaporator for cooling said chamber, operating means for supplying refrigerant liquid to said evaporator and for withdrawing refrigerant vapor therefrom, a closed tubular member formed of heat-conducting material, said member having an upper and a lower portion, the lower portion of said member being in heat-conducting relationship with said evaporator, the upper portion of said member being exposed to the air in said chamber, a volatile fluid in said member, a thermostat including a temperature-responsive element lying in heat-transfer relationship with the upper portion of said member, said thermostat controlling said operating means to activate the same when the temperature of said temperatureresponsive element rises to above a certain value and to inactivate said operating means when said temperature drops to a certain value below 32 F. and heating means for warming said evaporator to above 32 F. to melt frost thereon.

5. The refrigerator defined in claim 4 wherein said heating means comprises means for so altering the action of said operating means that it supplies to and withdraws refrigerant liquid at a temperature of above 32 F. from said evaporator.

6. In a refrigerator comprising a chamber, a refrigerating system for cooling media in said chamber, said system comprising a low pressure side for vaporizing a volatile fluid, a high pressure side for condensing the vapor produced in said low pressure side and a pump for transferring vapor from said low pressure side to said high pressure side, a temperature-responsive element for controlling said pump, a heat-conducting member thermally connecting said ele ment and a portion of said low pressure side within said chamber, said heat-conducting member comprising a tubular member sealed from the air ambient said system and containing a volatile fluid, said member having upper and lower portions, the upper portion of said member being in heat-exchange relationship with said element and the lower portion of said member being in heat-exchange relationship with said portion of the low pressure side, and means for applying heat to the low pressure side of said system to effect defrosting of said system.

7. In a, refrigerator comprising a chamber, a refrigerating system for cooling media in said chamber, said system comprising a low pressure side for vaporizing a volatile fluid, a high pressure side for condensing the vapor produced in said low pressure side and a pump for transferring vapor from said low pressure side to said high pressure side, a temperature-responsive element for controlling said pump, said temperatureresponsive element being responsive, at least in part, to the temperature of the air in said chamber, a heat-conducting member connecting said element and a portion of said low pressure side which contains refrigerant liquid, said heat-conducting member comprising a blind tube connected to and in communication with a portion of said low pressure side and extending to a. region above the refrigerant liquid level in said portion, and means for periodically warming said low pressure side to above 32 F. to melt frost thereon.

GRAHAM S. MCCLOY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,913,433 Dable June 13, 1933 2,036,565 Brouse Apr. 7, 1936 2,042,568 Tuska June 2, 1936 2,064,396 Volpin Dec. 15, 1936 2,169,284 Ploeger Aug. 15, 1939 2,192,848 Buchanan Mar. 5, 1940 2,208,267 Ridge July 16, 1940 2,324,309 McCloy July 13, 1943 2,366,635 McCloy Jan. 2, 1945 2,459,083 McCloy Jan. 11, 1949 2,459,173 McCloy Jan. 18, 1949

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