US2780072A - Two-temperature refrigeration system - Google Patents

Description

Feb. 5, 1957 M. Y. WARNER TWO-TEMPERATURE- REFRIGERATION SYSTEM im m Filed Oct. 27, 1955 ATTORNEY United States atent TWO-TEMPERATURE REFRIGERATION SYSTEM Milton Y. Warner, Evansville, Ind., assignor, by mesne assignments, to Whirlpool-Seeger Corporation, a corporation of Delaware Application October 27, 1955, Serial No. 543,225

4 Claims. (Cl. 62-4) This invention relates generally to refrigeration sys tems, and more specifically to an improved two-temperature refrigeration system having two evaporators operating at different temperatures and connected to a single compressor and condenser.

Many two-temperature or two-zone refrigeration systems are so constructed that one of the temperatures is controlled, or one of the zones is refrigerated, by means of a secondary refrigeration system. A secondary refri'geration system, as is well-known in the art, comprises an enclosed tubular system operating at a uniform pressure to conduct heat from a warm to a cold region by the evaporation of the refrigerant within the lower warm zone and the condensation of the refrigerant in the upper cold zone. The cold zone generally is at a temperature of F., while the warm zone is usually maintained at a temperature of 40 F. All of the heat removed from the warm zone must pass through the upper cold zone. Further, as is well-known in the art, the upper cold zone is usually cooled by an evaporator maintained at 0 F. Now, the capacity of a compressor operating a system having at 0 F. evaporator is approximately one-half of the capacity of that compressor at a 30 F. evaporator temperature. The efficiency of the compressor is likewise considerably higher at the 30 F. evaporator temperature range. Thus, it can be easily seen that in a two-temperature refrigeration system including a secondary refrigeration system, the capacity of the compressor is reduced and the efficiency of the system is lowered when all of the heat removed must pass through the 0 F. evaporator. Therefore, it is an object of this invention to provide a two-temperature refrigeration system having evaporators operating at different temperatures and connected to a single compressor and condenser, wherein the system is so connected as to allow eflicient operation of the single compressor in removing heat from each evaporator.

It is another object of this invention to provide a twotemperature refrigeration system having two evaporators wherein the flow of refrigerant within the system is such that the evaporator operating at the lower temperature will not be starved of refrigerant when the system is operating in a low ambient temperature.

A feature of the present invention is the mounting of a temperature-responsive magnetically operated valve within the accumulator of the evaporator operating at the higher temperature.

Other objects and features of the present invention will be apparent upon a perusal of the following specification and drawing wherein the invention is shown in a diagrammatic form.

The present embodiment is the preferred embodiment, but it is to be understood that changes can be made in the present embodiment by one skilled in the art without departing from the spirit and scope of this invention.

Generally, the invention comprises a single refrigeration compressor of any type well-known in the art, a single condenser 11 of any suitable type, a first evaporator 12, a second evaporator 13, and various tubings andcontrol elements. It is intended that the present invention be mounted Within a conventional refrigerator having a freez er compartment and a general food-storage compartment. The evaporator 13 is intended to be mounted in the freezer compartment, and therefore, will operate at a temperature of approximately 0 F. The evaporator 12 is mounted within the general food-storage compartment of the refrigerator and will operate at a temperature approximately 330 F. The evaporators 12 and 13 may be of any type well-known in the art; however, in the present embodiment, the evaporator 12 is a conventional platetype evaporator having a length of serpentine tubing disposed therein in a vertical arrangement, and the evaporator 13 is a conventional U-type evaporator. The ends of the serpentine tubing of the evaporator .12 are connected into a tank-like accumulator 14. The accumulator 14 is shown in cross section in the drawing, and may be of any type well-known in the art. The inlet end of the serpentine tubing of the evaporator 12 is connected into the accumulator 14 at a point below the outlet connection thereof, but above the inlet end of capillary tube 25, as can easily be seen in the drawing. The evaporator 13 is provided with an accumulator 15 and a pair of mounting walls 16 for mounting of the evaporator 13 to one of the inner walls of a refrigerator cabinet.

Turning next to a detailed description of the present invention, reference is made to the drawing. The refrigerant compressor 10 is directly controlled and operated by the thermostatically responsive element 17 and power line 18. The thermostatic bulb 19 is mounted to one side of the evaporator 13 adjacent the accumulator 15 thereof and in thermal contact therewith, and a length of capillary tubing 20 is connected between the thermostatic bulb 19 and the element 17. The thermostatic bulb 19 and the capillary tubing 20 are filled with a gas or liquid which will expand and contract in a direct proportion to the rise and fall of the temperature of the evaporator 13 and the accumulator 15. The control element 17 is constructed, as is well-known in the art, so that the power is connected to the compressor 10 through the cable 18 when a certain temperature of the evaporator 13 and the accumulator 15 is reached, and such that power is disconnected from the compressor 10 when the temperature of the evaporator 13 and the accumulator falls to a certain value. The certain values of temperature at which the compressor 10 will be caused to operate and to stop operating, by means of the control element 17, may be varied or adjusted by the rotatable control knob 21. It will be assumed for purposes of this explanation that the control knob 21 is so set that the compressor 10 will be caused to operate when the temperature of the evaporator 13 and the accumulator 15 rises above 0 F. and the compressor 10 will stop operating when the temperature of the evaporator 13 and the accumulator 15 falls to a temperature of 0 F.

The compressor 10 is provided with an outlet or discharge tube 22 and an inlet or suction tube 23. The discharge tube 22 is connected to one end of the condenser 11, and the other end of the condenser 11 is connected to a length of capillary tubing 24. The otherend of the length of capillary tubing 24 is connected into the accumulator 14. A short length of capillary tubing 25 is connected into the lower portion of the accumulator 14, and is further connected to the inlet of the evaporator 13. The accumulator 15 of the evaporator 13 is connected to a length of tubing 26 by a length of tubing 27, and one end of the length of tubing 26 is connected to the inlet or suction tube 23 of the compressor 10. The other end of the length of tubing 26 is connected through the bottom of the accumulator 14 into a valve 28.

The valve 28, which is partially shown in cross section in the drawing, is mounted partially-within the accumutinl' 'nmuntea within the accumulator 14 and a valve plunger 31. The valve body is provided with a port 30 connected to the length-of. tubing l fi through the lower surface vof the accumulator: 1 4. The valve body: 29 is further provided with apair of ports-44 openingYinto the interior of the accumulator l4 substantially at the top thereof. The pair of ports 44 and the port 30 are interconnected by a valve chamber having a valve seat therein. valve plunger 31 is slidablymounted within the valve body29 and is provided with a valve head at one end thereof for cooperation with thevalve seat. The valve plunger 31 is'forrned of a magnetically attractable material, such as soft iron. The thin walled tubularpart of valve body 29. which extends above the accumulator 14 ismade of a non-magnetiomaterial. The valve plunger '31.is so disposed within the valve "body 2) that the valve head there of .is seated against the valve seat, to close off any communication between the :pair of ports 44 and the port -30, by the force of gravity acting upon the valve plunger 31 in a downward direction. To lift the valve plunger 31 from the valve seat, a pair of rings 32 are provided. The rings 32, which are shown in cross section in the drawing, are formed of an easily magnetizable material, such as soft iron, and are positioned in a spacedapart relationship about a portion of the valve body 29. Further, a bar magnet 33 is provided. The magnet 33 is pivotally mounted by means of an arm 34 with the poles of the magnet movable toward and away from respective ones of the pair of rings 32. A bellows 35 is provided for pivotal movement of magnet 33. One end of the bellows 35 is rigidly mounted in the system, and the other end of the bellows 35 is connected through a short link 36 to the arm 34 connected to the magnet 33. Thus, as the bellows 35 expands, the magnet 33 will be pivoted against the pair of rings 32, and as the bellows 35 contracts, the magnet 33 will be pivoted away from the pair of rings 32 and against a stop element 37. The bellows 35 is caused to expand and contract by means of a-thermostatic bulb 38 connected to a length of capillary tubing39, which is in turn connected into the bellows 35 through the rigidly mounted end thereof. The thermostatic bulb 38 is filled with a vapor which will expand and contract in a direct proportion to a raising and lowering of the temperature at the thermostatic bulb 38. The thermostatic bulb 38 is mounted in thermal contact with the lower portion of thecvaporator 12 sothat even though the evaporator 12 may not at sometime be completely filled with liquid refrigerant, a small amount of liquid refrigerant within the evaporator 12 will be sufficient to affect the thermostatic bulb 38. Thus, itcan be seen that when the thermostatic bulb 38 isheated by the lower portion of the evaporator 12 to a certain degree, the bellows 35 will expand to move the magnet 33 against the-rings 32. The rings 32 will become magnetized and wilhattract the valve plunger 31. The valve plunger 31 will then be drawn upward to a position 'between the rings 32, and a magnetic circuit will then be completed through the magnet 33, one of the rings 32, the valve plunger 31,-the other ring 3 2, to the magnet 33. When the evaporator 12 cools the thermostatic bulb 38 to a certain degree, the bellows 35-w ill contract, moving the magnet 33 away from the rings 32. The previously described magnetic. circuit will thenbe broken and the valveplunger 31 will drop against-the valve seat within the valve body 29.

Turning next to a detailed description of the operation of the present invention, reference is again-made to the drawing. Firstly, :assuming that the evaporator 12 is at atemperature Wherein no cooling by the evaporator-12 is required, but that theevaporator 13 has risen toya temperature gabove E, thereby necessitating, cooling --by the evaporator -1-3. "Thethermostatic-bulb-d9 operating through, thexlength 50f capillary Y 2.0 :will pause-the .cont'rol element 1 7"to-operate; through :-the cable 1 8Lto pause the compressor 10 to operate. The compressor 10 will operate in a conventional mannerto discharge warm 66inpressed refrigerant vapor through the outlet tube 22 into the condenser 11. The refrigerant will be cooled and condensed to a liquid within the condenser 11 and will then be metered through the length of capillary tubing 24 into the accumulator 14. -Since the valve 28 is closed, no refrigerant vapor will be drawn from evaporator12 -or accumulator 14. Refrigerant vapor will be drawn from evaporator 13 causing a difference in pressure-between accumulator 14 and evaporator 13. Liquid refrigerant will then flow from the lower portion of the accumulator 14 through the length of capillary tubing 25 and into the evaporator 13. The flow of refrigerant vapor from evaporator 13 through the tubes 27- and 26 to the compressor 10 results in a reduction in vapor pressure in evaporator 13 which causes liquid refrigerant to evaporate, absorbing heat, and lowering the temperature of the evaporator. When the evaporator 13 has been cooled to 0 F., the thermostatic bulb 19 will cause the control elements17 to stop the compressor 10. a I

Assuming next that the evaporator 13v does not 'require cooling, but that the evaporator 12 has been heated to a temperature above 33 F. and consequently requires cooling. The thermostatic bulb v38 in thermal. contact with one of the lower runs of the evaporator 12, and operating through the length of capillary tubing 39 will cause an expansion of the bellows 35. The expansion of the bellows 35 will cause the magnet 33 :to be moved against the rings 32, thereby causing an opening of the valve 28. Refrigerant vapor will then flow from the upper end of the evaporator 12, through the upper portion of the accumulator 14, into the .p0rts.44, and out of the port 30. Some of the refrigerant vapor flowing from the port 30 will flow through the length of tubing 27 and into the accumulator 15 which has a lower temperature than evaporator 12. Since the thermostatic bulb 19 is mounted adjacent to the accumulator 15 in thermal contact therewith, the condensationof refrigerant vapor therein will raise the temperature of the thermostatic bulb 19 to cause an operation of the compressor-ltlthrough the control element 17 and the cable 18. When the compressor 10 begins to operate, the r egfrigerant Vapor will be drawn through the lenght of tubing 26 and into the suction tube 23, thus bypassing evaporator13. Warm compressed'refrigerant vapor will flow from the exhaust tube .2 2 into the condenser 11, wherein the refrigerant will be cooled and condensed. The liquid refrigerant will then flow through the length of capillary tubing 24 into the accumulator 14. The liquid refrigerant will then be delivered to the evaporator 12 through the lower or inlet end thereof. As the liquid refrigerant-within the evaporator 12 changes to a vapor state with the resulting cooling of the evaporator '12, the refrigerant vapor will be drawn from the upper or outlet end of the evaporator 12 into the upper portion of theaccumw later 14, through the ports 44, throughthe body ;29of the valve 28, and out of the port 30 to complete the cycle. Thus, the heat extracted from the warmer; evaporator need not pass through the-cooler evaporator. When the evaporator 12 is cooled to-a temperautre of 33, the thermostatic bulb 38 will cause a contract-ion of-the bellows 35, thereby causing valve '28 to close. Refrigerant vapor within the accumulator 15 will Then-drawn therefrom and the thermostatic bulb '19 will then be cooled to a degree wherein the compressor '10 :willbe stopped.

'When a system similar toithatherein described isfopcrating in a low ambient temperature,-in otherwords, When the condensing temperatureis low,"it is well-known in the :art that-liquid refrigerant tends to eaecumulate' in the condenser of such a system to "tliereby'istarve Tth'e evaportao'r orzevaporators. "It is espe'cially ihiportant that the (low-temperature evaporator 213' :should not be estarved of ;refrigerant in .a greater pr oporti'dn itlian the warmer evaporator. To accomplish this desired efifect, the capillary tubing 24 is connected directly to the accumulator 14. Further, the length of capillary tubing 25 is connected into the lower portion of the accumulator 14. Additionally, the inelt and outlet ends of the evaporator 12 are connected into the accumulator 14 above the connection of the capillary tubing 25 thereto with the outlet end of the evaporator 12 connected substantially at the top of the accumulator 14. Also, the thermostatic bulb 38 is mounted to a lower run of the vertically disposed evaporator 12 so that the thermostatic bulb 36 may respond to reduced temperatures in that lower section when the evaporator 12 is only partially filled with liquid refrigerant. When the partially filled evaporator 12 is cold enough to satisfy the thermostatic bulb 38, the valve 28 is closed, and liquid refrigerant is then delivered to the second evaporator without the necessity of first filling the coils of the evaporator 12.

Since the evaporated refrigerant within the evaporator 12 is drawn from the accumulator 14 through the length of tubing 26 to the compressor 10, it can easily be seen that the heat removed from the evaporator 12 does not have to pass through the 0 F. evaporator 13. Thus, the capacity of the compressor and the efficiency of the system is relatively high.

Having described the invention, what is considered new and desired to be protected by Letters Patent is:

1. In a household refrigerator having an above-freezing food storage chamber and a below-freezing frozen food chamber, a refrigeration system including a plate evaporator provided with sinuous coils and located in said above-freezing food storage chamber, an accumulator, the said evaporator having its tube ends connected to said accumulator, a freezing evaporator, said freezing evaporator having a receiver at its suction outlet and being located in said below-freezing chamber, a motor compressor having its outlet connected to a condenser, a capillary tube leading from said condenser to said accumulator and forming a restrictor, said capillary tube being in heat conducting relation with said suction tube leading from said receiver to said motor compressor inlet, and a second capillary tube extending from the outlet of said freezing evaporator to the lower end of said receiver, a cold control comprising a thermostatic switch controlling the circuit of said motor compressor and having a bulb in heat conducting relation with the outlet of said below-freezing evaporator, a suction pipe connection from said suction pipe to a valved conduit in said receiver, said valved conduit having a valve seat and a paramagnetic valve plunger, said plunger engaging said valve seat at a port communicating with the interior of said accumulator, and said plunger being reciprocably mounted in a closed tube extending from said receiver, a magnetic core having a pair of annular poles surrounding said tube and adapted to act on said plunger, and a thermostatic member responsive to temperature of said above-freezing evaporator for moving a magnet and cansing polarization of said poles to act on said plunger and open said valve, the said evaporators being connected in parallel by said suction tube, receiver, and capillaries so that heat removed from either evaporator may be carried back directly to the compressor inlet to increase its efficiency.

2. In a refrigeration system, a first evaporator adapted for operation at a certain temperature, a second evaporator adapted for operation at a lower temperature, said first evaporator formed of a length of serpentine tubing disposed in a vertical plane, an accumulator for said first evaporator, the ends of said serpentine tubing con nected into said accumulator in a vertically stacked arrangement, a second accumulator connected to said second evaporator, valve means mounted partially within said first accumulator, thermostatically responsive means mounted in thermal contact with the lower portion of said length of serpentine tubing and operating responsive to the temperature thereof for controlling the operation of said valve means, tubing means connected into said valve means through said first accumulator and connected to said second accumulator for the passage of vaporized refrigerant therethrough, a second thermostatically responsive means mounted in thermal contact with said second evaporator and said second accumulator, means for drawing vaporized refrigerant through said tubing means, said last-mentioned means operating responsive to the operation of said second thermostatically operated means.

3. In a refrigeration system having a plurality of evaporators, an accumulator for one of said evaporators connectible to the inlet and outlet openings thereof, openings provided through the lower portion of said accumulater for the ingress and egress of liquid refrigerant therethrough, a valve partially mounted within said accumulator, said valve having a valve port through said accumulater for connection of a refrigerant suction line thereto, a second valve port mounted through said valve within said accumulator for the passage of vaporized refrigerant therethrough, a valve seat disposed within said valve between said ports, a valve plunger slidably mounted within said valve for cooperation with said valve seat, said valve plunger formed of a magnetically attractable material, magnetic means mounted without said accumulator in cooperation with said valve plunger for operation thereof.

4. In a refrigeration system as claimed in claim 3, said magnetic means comprising a pair of rings mounted in a spaced-apart relationship about the portion of said valve mounted without said accumulator, said rings formed of a magnetically attractable material, and a bar magnet pivotally mounted for cooperation with said rings, whereby said magnet is pivotable against said rings to cause a temporary magnetization thereof to in turn cause an attraction and upward movement of said valve plunger.

References Cited in the file of this patent UNITED STATES PATENTS 2,074,137 Whitesel Mar. 16, 1937 2,168,367 Kucher Aug. 8, 1939 2,182,824 Schweller Dec. 12, 1939 2,640,327 Alsing June 2, 1953 2,641,109 Muffly June 9, 1953

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