US2530338A

US2530338A - Temperature control apparatus

Info

Publication number: US2530338A
Application number: US743049A
Authority: US
Inventors: Jr John A Mclean
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1947-04-22
Filing date: 1947-04-22
Publication date: 1950-11-14
Anticipated expiration: 1967-11-14

Description

Nov. 14, 1950 Filed April 22, 1947 J- A. M LEAN, JR

TEMPERATURE CONTROL APPARATUS 2 Sheets-Sheet 1 WITNESSES:

lNVENTOR JOHN A. MLEAN JR.

ATTORNEY 1950 J. A. MOLEAN, JR 30,338

TEMPERATURE CONTROL APPARATUS Filed April 22, 1947 2 Sheets-Sheet 9 WITN ESSES:

INVENTOR JOHN G. MCLEAN IR.

g QM ATTORN EY Patented Nov- 14, 1950 2,530,338

UNITED STATES PATENT OFFICE TEMPERATURE CONTROL APPARATUS John A. McLean, J r., Springfield, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 22, 1947, Serial No. 743,049

2 21 formed of two

metal sheets

28 and 30 which are welded together. embossed to provide refrigerant passages 32, a refrigerant inlet 34 to said passages 32, and re- It is an object of the invention to provide a 5 frigerant headers 36. The cooling unit 26 also control system for the primary refrigerating comprises a metal top plate 38 and a metal rear apparatus in a refrigerator employing a secondplate 48 secured to the top edges and the rear ary volatile refrigerant circuit, which system edges, respectively, of the U-shaped element 21. maintains satisfactory temperatures for freezing A convoluted metal refrigerant tube 42 is foods. brazed to the upper surface of the top plate 38 It is another object of the invention to provide and the rear surface of, the rear plate 48 and a control system for a refrigerator of the type communicates at its lower end with the inlet 34 described, which system maintains substantially of the U-shaped element 21. The cooling unit uniform temperatures in spite of variations in here described is more fully shown and described ambient temperatures. in the patent application, Serial No. 668,950 of It is a further object of the invention to pro- Jues N. Saler, filed May 10, 1946. vide a control system for a refrigerator of the The cooling unit 26 is adapted for freezing type described, in which the thermostat may foods and is supplied with a volatile refrigerant have a large temperature differential. liquid by the refrigerant apparatus 28 in the These and other objects are effected by the lower compartment It. The apparatus 20 cominvention as will be apparent from the following prises a sealed casing 44 enclosing a compressor description and claims taken in connection with and an electric motor for driving the compressor. the accompanying drawings, forming a part of A suction tube 46 connects the casing 44 with one this application, in which: of the headers 36. The compressor withdraws Fig. 1 is a view in elevation of a refrigerator refrigerant vapor from the header 36 through with parts broken away and embodying the the suction tube 46, compresses the vapor, and invention; forces it through a tube 48 into a condenser 56 Fig, 2 is a, sectional view on th li 11-11 or wherein the refrigerant vapor is liquefied. The Fig, 1; and refrigerant liquid flows through a capillary tube Fig. 3 is a view in perspective of the secondary 30 52 to the tube 42 wherein a portion of the rerefrigerant circuit and a phantom view of the r t liquid Vaporizes- The remaining einner liner of the refrigerator cabinet to whic frlgerant liquid and the refrigerant p r Pa s the secondary circuit is secured. to the inlet 34 of the U-shaped element 21 where- Referring now to the drawings for a description in the complete vaporization o the efrigerant of the invention, the reference numeral I0 desig- 35 liquid takes p nates the outer metal, shetl of a refrigerator h low r p r n f t upp mpartment cabinet l2. A horizontal partition l4 divides the IB is maintained at a t p rature of about 0 cabinet l2 into an upper compartment [6 for the F. and constitutes the area where frozen foods freezing and storing of frozen foods and a lower y be s d- This portion is cooled by a concompartment l8 for the refrigerantsupplying 40 Ventional flow 0f from the cooling it 26 apparatus 20. The upper compartment l6 comand also by a secondary volatile refrigerating prises on inner metal liner 22 spaced from the circuit 54. The secondary circuit 54 consists of outer metal shell I!) and the partition l4. Ther- 9. closed tube which has been evacuated and mal insulating material is disposed between the fi l d partially with a volatile refrigerant liquid side, rear, and top walls of the inner liner 22 and through the filler pipe 55. The secondary circuit the corresponding walls of the outer shell I3. 54 includes a first portion 56 lying adjacent to Thermal insulating material 24 is also disposed and in heat-transfer relation with some of the betweenthe bottom wall of the inner liner 22 and convolutions of the tube 42 on the rear plate 48 the partition l4. A door 25 of similar construcof the cooling unit 26. The first portion 56 tion closes the front opening of the cabinet I2. 50 serves to condense refrigerant vapor into a.

A primary evaporative cooling unit 26 is seliquid. The secondary circuit 54 also comprises cured, by means not shown, in the upper portion a second portion 58 secured to the side, rear and of the upper compartment IS. The cooling unit bottom walls of the inner liner 22. The sec- 26 may be of any convenient design but is here 0nd. portion 58 cools the upper compartment shown as comprising a broad U-shaped element 55 I6 and absorbs the heat which penetrates The

sheets

28 and 30 are accuses 3 through the thermal insulation 24 thereof. The secondary circuit also includes a third portion 66 which conducts the vaporized refrigerant from the second portion 58 to the first portion 66 of the secondary circuit 64. The secondary circuit 54 also comprises a fourth portion 62 for conducting the refrigerant liquefied in the first portion 56 to the second portion 66. A part 64 of the fourth portion 62 lies in the thermal insulation 24 of the refrigerator cabinet l2 and out of thermal contact with other portions of the refrigerator so that the temperature of part 64 correspond substantially to the temperature of the refrigerant flowing therethrough. A tube 66 is intimately brazed to the part -64 for a purpose which will be explained subsequently.

The electric motor in the sealed casing 44 of the refrigerant-supplying apparatus 20 is energized through the electrical leads 66 and a thermostatic control is interposed in one of the leads 68. The control 10 comprises a switch 12 actuated by a metal bellows 14 through an over-center spring 16 which affords a snapacting movement to the switch 12 in a manner well understood in the art. The metal bellows l4 communicates through a tube 18 with a bulb 66 located in the tube 66.

The bellows 14, the tube I8, and the bulb 66 are evacuated and charged with a small quantity of a volatile liquid so that the pressure within the bellows I4 is responsive to the temperature of the liquid in the bulb 60 when the refrigerant apparatus 20 is in operation. It will thus be apparent that the switch 12 is opened and closed in response to the temperature of the bulb 80 and that the switch 12 controls the operation of the electric motor and hence of the compressor to actuate the compressor whenever the temperature of the bulb so rises above a predetermined temperature such as 1 F. and stops the compressor whenever the temperature of the bulb 80 is reduced to a second predetermined temperature such as minus 7 F. Since the temperature of the bulb 60 corresponds to the temperature of the part 64 of the secondary circuit, the refrigerating apparatus 26 is controlled by the temperature of the refrigerant flowing therethrough.

The advantages of placing the thermostatic bulb 80 in heat transfer relationship with the refrigerant liquid flowing through the part 64 are as follows:

First, when a large quantity of food is placed in the primary evaporative cooling unit 26 to be frozen, the refrigerating apparatus 26 will run substantially continuously. This is caused by the fact that the refrigerant liquid in the primary cooling unit 26 is vaporized rapidly by the relatively warm food. This tends to raise the suction pressure of the refrigerant supplying apparatus 20 since its pumping capacity is limited. The increased suction pressure causes the temperature of the refrigerant in the tube 42 to rise, and the part 64 of the secondary circuit is not cooled to the assumed temperature of minus 7 F. at which the thermostatic control I6 stops the compressor. The refrigerating apparatus 26 is thus caused to operate at its maximum capacity to freeze the food.

Second, the thermostatic control 10 may be of the wide temperature differential type, the temperature differential between starting and stopping the apparatus 20 being about 8 F. This is caused by the fact that the changes in the temperature of the part 64 are closely related 4 to the changes in the temperature of the primary cooling unit 26v because the refrigerant liquid" condensed in the first portion 66 by the primary cooling unit 26 flows directly through part 64. The changes in temperature of the primary cooling unit 26, in turn, are directly responsive to the running cycles of the refrigerant apparatus 20, so that the temperature of part 64 normally drops when the refrigerating apparatus 20' is in operation and rises when said apparatus stops.

Third, the location of the bulb on the secondary refrigerant circuit insures a constant temperature in the frozen food storage area of the upper compartment l6 when the ambient temperature of the refrigerator varies. It will be readily apparentthat if the temperature of the refrigerant liquid supplied to the second portion 66 of the secondary circuit 54 is held between the aforementioned predetermined limits, the temperature of this portion 58 will also be held substantially to these limits in spite of changes in the heat load caused by increases in the ambient temperature. This alone would not keep the temperature in the storage area substantially constant because the increased heat leakage through the walls of the cabinet not cooled by the portion 58 of the secondary circuit 56 (such as the door 25, the upper wall, and the upper portions of the side and rear walls of the compartment l6) would allow additional heat to leak in. This additional heat leakage, however, is offset by the lower temperature at which the primary cooling unit 26 is forced to operate to absorb all of the heat supplied by the first portion 56 of the secondary circuit 54. This lower temperature of the primary cooling unit 2|] thus additionally cools the storage compartment by convection and tends to hold its temperature constant.

Fourth, the temperature of the frozen food storage area tends to remain constant if relatively warm foods are placed therein, since the primary cooling unit 26 will be forced to operate at a lower-temperature under these conditions to absorb all the heat supplied by the secondary circuit 54 as explained above.

It will be apparent from the above that this invention provides a location for the control bulb of a refrigerator utilizing a secondary refrigerant circuit, which location affords rapid freezing of foods in the primarycooling unit, a substantially constant temperature in the food storage area, and allows the use of a wide differential control.

While I have shown my invention in but one form, 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 refrigerating mechanism, the combination of a primary evaporator, apparatus for supplying said primary evaporator with a volatile liquid refrigerant and for withdrawing vaporized refrigerant from said evaporator, thermostatic control for rendering said apparatus active and inactive, and a secondary volatile refrigerant circuit operating at the same pressure throughout, said secondary circuit having a first portion in heat transfer relationship with said primary evaporator for condensing refrigerant vapor in said secondary circuit, said circuit having a second portion for absorbing heat to vaporize refrigerant liquid in said circuit, said secondary circuit having a. third portion for conducting refrigerant vapor from said second portion to said first portion, said circuit also having a fourth portion for conducting refrigerant liquid from said first portion to said second portion, said thermostatic control including a temperature-responsive actuating element in heat-transfer relationship substantially solely with said fourth portion of said circuit.

2. In a refrigerator, the combination of a thermally insulated chamber, a primary evaporator for cooling said chamber, refrigerating apparatus.

far supplying said primary evaporator with refrigerant liquid and for withdrawing refrigerant vapor from said evaporator, a secondary volatile refrigerant circuit operating at a uniform pressure throughout, said circuit having a first portion in heat transfer relationship with said primary evaporator, a second portion for cooling said chamber, a third portion for conducting refrigerant vapor from said second portion to said first portion, and a fourth portion for conducting refrigerant liquid from said first portion to said second portion, said fourth portion having at least a part which does not lie in direct heat-conducting relationship with said primary evaporator, or with said first, second, or third portion of the secondary circuit, and a thermostatic control for rendering said apparatus active and inactive, said thermostatic control including a temperature-responsive actuating element lying in heat-transfer relation with said part of the fourth portion of said circuit.

3. The refrigerator structure defined in the immediately preceding claim wherein the primary evaporator is located within said chamber.

4. In a refrigerator, the combination of a chamber having metal walls and thermal insulating material on the outer surface of said walls, a primary evaporator in the upper portion of said chamber, refrigerating apparatus for supplying said primary evaporator with refrigerant liquid and for withdrawing refrigerant vapor from said evaporator, a secondary volatile refrigerant circuit operating at a uniform pressure throughout, said circuit having a first portion in heat-transfer relationship with said primary evaporator, a second portion in heat-transfer relationship with extensive portions of said metal walls,-a third portion for conducting refrigerant vapor from said second portion to said first portion, and a fourth portion for conducting refrigerant liquid from said first portion to said second portion, said fourth portion having at least a part which does not lie in direct heat-conducting relationship with any of said metal walls, with said primary evaporator or with said first, second, or third portion of the secondary circuit, and a themostatic control for rendering said apparatus active and inactive, said control including a temperature-responsive actuating element lying in heattransfer relationship with said part of the fourth portion of said-circuit.

5. The refrigerator structure defined in the immediately preceding claim wherein said second portion is not in heat-transfer relationship with all of the walls of said chamber and wherein the primary evaporator assists in cooling the chamber.

6. The refrigerator structure defined in the immediately preceding claim wherein said part of the fourth portion of said circuit and said temperature-responsive element are embedded in said thermal insulating material.

JOHN A. McLEAN. JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS