US2462240A - Two-temperature refrigerator system - Google Patents

Description

Feb. 22, 1949.

P. D. VAN VLIET ETAL TWO-TEMPERATURE REFRIGERATOR SYSTEM Filed March 21, 4945 3 Sheets-Sheet 2 Feb. 22, 1949. J P. D. VAN VLlET ETA]. 2,462,240 I TWO-TEMPERATURE REFRIGERATOR SYSTEM Filed March 21, 1945 s Shqets-Sheet :5

Patented Feb. 22, 1949 TWO-TEMPERATURE REFRIGERATOR SYSTEM Paul D. Van Vliet and Bartell J. Homkes, Galesburg, 111., assignors tn Liquid Carbonic tion, Chicago, 111., a corporation of Delaware Application March 21, 1945, Serial No. 583,925

11 Claims. (Cl. 62-4) refrigerators and is adapted for use in domestic refrigerators.

One purpose is to provide an improved two temperature refrigerator.

Another purpose is to provide a two temperature refrigerator in which a single refrigerant condensing unit is employed to circulate a volatile refrigerant through evaporators employed to cool separate storage compartments to diflerent temperatures. I

Another purpose is to provide improved control means for a two temperature refrigerator.

Another purpose is to provide an improved refrigerant circuit for two temperature refrigerators.

Another purpose is to provide an improved system for delivering liquid refrigerant selectively to the evaporators of separate compartments in a two temperature refrigerator.

Other purposes will appear from time to time in the course of the specification and claims.

The invention is illustrated more or less diagrammatically in the accompanying drawings wherein: V

Figure 1 is a vertical section of a two temperature refrigerator;

Figure 2 is a section at the line 2-2 of Figure Figure 3 is a diagrammatic showing of the refrigeration system and electrical circuit; and

Figure 4 is a diagrammatic showing of an alternative defrosting means.

Like parts are indicated by like symbols throughout the specification and drawings.

Reierring to the drawings, A generally indicates a food storage cabinet including an insulated back wall I, insulated side walls 2, an insulated top wall 3, an insulated bottom wall 4, and an insulated intermediate partition 5. The above mentioned walls and partitions define two storage compartments which are separated from and insulated from each other. 6 is an insulated door for the upper compartment and 1 an insulated door for the lower compartment. Thus the two storage compartments are insulated from each other and from the outside air. Any suitable gasketing or sealing means may be employed, it being understood that the details of the walls. doors and sealing means do not of themselves form part of the present invention. Any suitable means may be employed for limiting to a minimum heat transfer between the inside of the compartments and the outside air, and between the two compartments.

For convenience, the upper compartment is indicated as B and the lower compartment as C. Located below the lower compartment 0 is an uninsulated space for a condensing unit, with a closure ID.

The upper storage compartment B is preferably held at a relatively high temperature as from 35 to 45 degrees Fahrenheit. The interior of the compartment C may be maintained at a temperature substantially below freezing, as from 0 to 10 degrees Fahrenheit, to adapt it for quick freezing and for cold storage of frozen goods.

Referring to the details of the compartments, it is advantageous to employ a liner or sleeve of sheet metal for each compartment, with evaporator coils on the exterior of each such sleeve, in heat transfer relationship therewith. In connection with the upper compartment B is indicated a sleeve including a vertical rear wall ii, side walls i2, a top wall l8, and a bottom wall i4. it indicates an evaporator coil which may extend about three sides of the liner or sleeve thus formed. namely about the rear wall ii and each of the side walls 22. The length of the coil and the area of wall with which it is in contact may be varied to cause the refrigerant to be evaporated at the desired temperature, preferably somewhat above freezing, to prevent frost and to minimize dew formation on the walls, and to insure a sufiiciently high relative humidity to prevent dehumidification of stored food. The storage space of compartment B is bounded at the bottom by an insulating food storage shelf it which is shown as supported several inches above the bottom wall N, of the upper sleeve. It is convenient to identify the space below the insulating food shelf as the ice cube forming and storage compartment E. In the compartment E is illustrated a shelf including an evaporator coil i i, this coil or evaporator being in series with the evaporator it. It is efiective to freeze the contents of any suitable ice cube tray or trays l8. Interposed in the line from evaporator IE to evaporator i! is a restrictor diagrammatically illustrated at H. Positioned below the evaporator i1 is any suitable defrosting pan i9. Any suitable gap or gaps 20 may be emaeeaseo 3 gaps or apertures provided, or it may be removably mounted on any suitable supports such as the spacing and supporting pins Ii.

In compartment is a liner sleeve including the back wall 25, side walls 2', bottom wall'il and top wall 2.. As in the case of the upper sleeve, any suitable evaporator coil may extend about the sleeve, being preferably exterior thereto but in heat transfer relationship therewith. The length and shape of the cell may be varied to suit desired conditions but it may advantageously extend about the walls II, 28 and 28, being preferably omitted from the bottom walijl.

With reference to the refrigerant condensing unit employed, any suitable means may be used. The particular mechanism herein illustrated is of the mechanical type. Since its details are not of themselves important the mechanism is illustrated only diagrammatically. ll illustrates any suitable compressor, driven for example from the motor Si. 32 is any suitable condenser coil and 33 a receiver. Any suitable means may be used to cause air to flow through the condenser, sueh'as a fan on motor 3|, or a separate motor and fan, or a chimney. The

liquid refrigerant, under pressure, is delivered along'the duct 34 to the thermal expansion valve generally indicated as 35, which may be of the type which has no thermal bulb and capillary tube but instead, has the suction gas returning through line 36, pass through the valve body, and apply suction pressure to the usual thermal expansion valve diaphragm, thus controlling superheat. 31 is a duct extending from the valve structure 35 to the three way solenoid valve 38, the details of which do not form part of the present invention and are not illustrated. It will be understood, however, that a liquid line 39 extends to the lower compartment C and a liquid line 40 to the upper compartment B. Any suitable means may be employed, such as the restrictor tubes 4| and 42, for maintaining pressure on the solenoid valve ports to prevent liquid refrigerant from expanding within the solenoid valve. When the refrigerant is circulating through the evaporator 15 it returns by the pipe 43 to the suction line 35. In series with the evaporator I5 is the ice cube tray shelf evaporator ll. 45 diagrammatically indicates a manual valve which permits shutting off the flow of refrigerant through coil ll, to permit defrosting. A bypass relief valve 44 normally shut, but opening when valve 45 is closed is provided, thus maintaining refrigeration on evaporator i5 whether valve 45 is open or closed. Another means of defrosting is diagrammatically shown in Figure 4 utilizing a three way manual valve 12 in theline from the evaporator II in one position feeding refrigerant through the restrictor' ll to the ice freezing evaporator i1, and in another position feeding direct to the suction line 38. In the second position there is no refrigerant flow through the evaporator i1 and defrosting will occur.

It will be understood that when refrigerant is flowing through the evaporator II, no refrigerant is flowing through the evaporator of the lower or colder compartment C. When the solenoid valve 38 is set to deliver refrigerant through tube 39 and restrictor 4| to. the low temperature evaporator 29, the refrigerant returns to the suction tube 36 through the tube 48. 48 is any suitable check valve in the pipe 4', adapted to prevent gas in the suction line from entering and 4 condensing in evaporator it when that evaporator is not being supplied with refrigerant.

The electrical circuits are as follows: Currentsupplyisthroughleadsllsndll. Lead ll runstocontactllintheswitchlland thecontactsllandilintheswitchll. When either switch is closed, current flows to the contact ll inthe switchflorthecontact in the switch ll, thence through the lead I! to the motor 3| and to the return lead l0, causing the motortorunwheneitherorbothswitchesare closed. I a

When the switch I! closes, the second contacts also close, current flowing to the contact II through the lead I. to the solenoid of the valve 38, returning through the lead I! to the return lead ll. Thus the solenoid-operated three way valve II is made to deliver refrigerant to the evaporator II when the switch I3 is closed, and to the evaporator a when the switch II is open. Both switches are operated thermally, with heat sensitive bulbs located in their respective compartments. In the operation of the device, with compartments B and C both warm, and calling for refrigeration, the switches it and II will both be closed. The solenoid of the valve It will be energized and it will deliver refrigerant along the pipe 40, through the restrictor 42, to the evaporator I! of the upper or warmer compartment B. When the compartment B is cooled to the desired temperature, the double pole switch 58 opens. The result is toalter the direction of flow from the solenoid valve and to cause refrigerant to flow through the tube II and restrictorf 4| to the evaporator It in the low temperature compartment C. The motor it heat responsive means, can always control the a three way solenoid valve 38 to insure that, whenever refrigeration is called for by a rise in temperature in the compartment B, the refrigerant is thereupon delivered to the evaporator ll of the upper cbmpartment for evaporation. But

should the flow of refrigerant to the lower evaDO:.,/--

rator ll be interrupted by demand for refrigeration for thejupper compartment B, itwill be resumed at once when the temperature in the upper compartment is suiliciently lowered to open the switch 53. When neither compartment calls for refrigeration, the switches II and ii are both-open, in response to action of the bulbs 42 and N. and the circuit through the motor ii is broken. and no refrigerant is delivered.

The advantages of the above described arrangement are many. The single refrigerating mechanism, with a single compressor and condenser, always operates at maximum suction pressure for either the high temperature or the lower temperature evaporator, whichever is in'eircuit, and operates at maximum output. The critical food compartment temperature is closely controlled. The evaporator coils can be of smaller tubing, because they operate independently.. and not in series. A single refrigeration condensing unit delivers refrigerant selectively to one or the other evaporator, but never to both at the same time.

In effect the two refrigerant condensing units u shown in the co-pending application Ber. No. 583,924 are replaced by the solenoid valve 3|, the expansion valve "and receiver 33, and a single pump or compressor having a somewhat greater. capacity than that of either of the two compressors of the dual pump system Zihe manual shut off valve 45 in the evaporator tray coil I1 is placed at the front for easy access. The relief valve ll serves as a bypass to let refrigerant gas from the evaporator I! pass directly to the suction pipe 36 when the manual shut ofi valve 55 is closed. The valve M may have a spring'so adjusted that it is tightly shut when the valve 45 is open.

To defrost, the valve is closed and is reopened when the evaporator i1 is clear of ice. If forgotten, the only eflect is that water will not be frozen by the evaporator i1. Refrigeration to the food compartment continues, even though the valve 45 is carelessly left shut.

Whereas the evaporator I! is shown in series through the restrictor II with the evaporator 55 of the warm compartment B it may, if desired, be included instead in the low temperature circuit, in series with the evaporator 29 and without the restrictor H. Defrosting procedure is the same, and refrigeration to compartment continues even though the valve is carelessly left shut.

It will be realized that, whereas, a practical and operative device is described and illustrated,

nevertheless many changes may be made in the size, shape, number and disposition of parts without departing from the spirit of the invention. Therefore the description and drawings are to be taken as illustrative or diagrammatic, rather than as limited to the precise showing.

The use and operation of the invention are as follows:

The requirements of a refrigerator having two compartments, one held at say 40 degrees F and the other at say from 0 to 19' degrees F. are that control of temperature in the warm compartment must be close, whereas a wider temperature fluctuation of the colder compartment is permissible. It is of primary importance to keep the refrigeration demand of the upper compartment B satis--' fled. In the present system each compartment is provided with heat responsive means for causing a flow of refrigerant to its evaporator, when the temperature in the compartment reaches a predetermined maximum. The present system is intended to insure that the call for refrigeration of the warmer compartment B takes precedence over the call for refrigeration of the colder compartment C.

We claim:

1. In a household refrigerator, a condensing unit, an evaporator in fluid circuit therewith, a storage compartment in which said evaporator is positioned, a second evaporator, in series with said first mentioned evaporator, adapted for ice cube freezing, a restricted passage :between said evaporators, a shut off valve for said second evaporator adapted, when closed, to prevent the flow of refrigerant through said second evaporator, and bypass means adapted to permit a return flow of refrigerant from said first mentioned evaporator to said condensing unit when said shut oif valve is closed.

2. In. a household refrigerator, a. storage compartment, a condensing unit, a space cooling evaporator in said storage compartment, in fluid circult with said condensing unit, constructed and arranged to maintain an above freezing temperature in said storage compartment, a second evaporator in said compartment, constructed and arranged to maintain a temperature sufficiently low for ice cube freezing, a shut off valve for said second evaporator, adapted, when closed, to prevent the flow of refrigerant through said second evaporator, and to cause its defrosting, and means for maintaining said space cooling evaporator in fluid circuit relationship with said condensing unit during the closure of said shut off valve.

3. In a household refrigerator, an insulated compartment, an expansion coil adapted to cool said compartment, means for circulating a volatile refrigerant through 'said coil, including a condensing unit in circuit therewith, a restrictor adapted to reduce the pressure of the refrigerant from said coil, a second expansion coil in series with the first coil and with the condensing unit,-

adapted for the freezing of cubes of ice, a shut oil! valve for said second expansion coil, adapted to prevent flow of refrigerant through saidcoil, and a normally closed bypass relief valve adapted to permit refrigerant to flow from the first coil back to the condensing unit when said shut off valve is closed.

4. In a household refrigerator, an insulated compartment, an expansion coil adapted to cool said compartment, means for circulating a volatilerefrigerant through said coil, including a condensing unit in circuit therewith, a restrictor adapted to reduce the pressure of the refrigerant supplied to said coil, a second expansion coil, in series with the first coil and with the condensing unit, adapted for the freezing of cubes of ice, a

adapted to reduce the pressure of the refrigerant supplied to said coil, a second expansion coil, in series with the first coil and with the condensing unit, adapted for the freezing of cubes of ice, a restrictor between said coils, adapted to reduce the pressure supplied to said second coil, and means for causing defrosting said second coil comprising a three way manual valve and above freezing in said compartment, 9. second evaporator in said compartment, adapted to freeze ice, a restricted refrigerant. connectin tube between said two evaporators, a refrigerant condensing unit and connections therefor,-

adapted to deliver liquid refrigerant to the space cooling evaporator and to withdraw gaseous refrlgerant from the freezing evaporator, and means effective during normal circulation of refrigerant through said space cooling evaporator,

, 1 for bypassing the refrigerant about said i'reesing evapora I. In refrigerator system, a pair of insulated compartments adapted to be cooled to diilerent temperatures, a separate evaporator for each compartment. constructed 'and arranged to cool said compartments to their desired temperatures, a single condensing unit in circuit with said evaporators, a motor therefor. an expansion valve in said circuit, a three way solenoid valve in said circuit, beyond said expansion valve, adapted to the'temperature of the colder compartment,

said switch including a single set of contacts adapted and connected, when closed, to energize said motor. I

8. In a refrigerator system, a pair of insulated compartments adapted to be cooled to diflerent temperatures, a separate evaporator for each compartment, constructed and arranged to cool said compartments to their desired temperatures, a single condensing unit in circuit with said evaporators, a motor therefor, a three way solenoid valve in said circuit, adapted to deliver refrigerant selectively to one or the other of said evaporators, in response to the energization or de-energization of said solenoid valve, a thermal switch responsive to temperature in the warmer compartment. said switch having two sets of contacts. one set adapted and connected to energize the solenoid valve and the other adapted and connected to energize said motor, and a second thermalsaid evaporators and motor therefor, a three way solenoid valve in said circuit, said circuit including fluid lines extending from said three way valve to evaporator of each said compartment, restrictors in each said line, switch means adapted to control-said solenoid valve in response to temperature conditions in the warmer of said compartments,. whereby refrigerant is fed to the evaporator of the warmer compartment whenever the temperature of said compartment rises above a predetermined minimum. and means eflective to cause refrigerant to be fed to the evaporator of the colder compartment, whenever the temperature of said colder compartment exceeds a predetermined minimum at a time that refrigerant is not being fed to the warmer compartment.

10. In a refrigerator system, two expansion coils, an expansion valve, a three way solenoid valve, and means for feeding a refrigerant from said expansion valve through said three way valve selectively to said expansion coils, including switching means adapted to energize or deenergize the solenoid valve, and restrictor tube means adapted to maintain such a pressure on the delivery parts of the three way valve as to maintain solid liquid through said valve.

11. In a household refrigerator. a refrigerant condensing unit, a storage compartment, a space through.

PAUL D. VAN VIII-'1. BAR'I'EIL J. nouxns. REFERENCES crrm The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,523,112 Fitzgerald Jan. 13,19 5 2,056,185 Bronaugh etal. Oct. 6, 1936 2,133,949 Buchanan Oct. 25, 1938 2,198,328 Brown et al Apr. 28, 1040 2,426,578 Tobey Aug. 28. 1947

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