US2133955A - Control for two-temperature refrigerators - Google Patents

Description

Patented Oct. 25, 1938 UNITED STATES.

PATENT orruzs CONTROL FOR TWO-TEMPERATURE REFRIGERATORS Leslie B. M. Buchanan, Springfield, Mass assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 22, 1936, Serial No. 106,976

' 14 Claims.

posed in the high and low temperature chambers to maintain the chambers at different refrigerated temperatures. It has been suggested, heretofore, to control the cooling effect of the higher temperature evaporator by operating a fan in the warmer compartment for circulating air over the warmer evaporator in response to 15 the temperature of the warmer compartment or evaporator. In accordance with my invention, such a system is utilized, and in addition preference is given to the colder compartment so that it will receive refrigeration when required, re-

gardless of the heat load on the warmer evaporator.

In the aforementioned prior art devices, the

fan was usually stopped with the condensing unit,.

or only was operated when the temperature of the warm compartment rose above a predetermined minimum. Such a system has several disadvantages. For example, the air in the warm compartment circulates very slowly when the fan is inactive with the result that some portions of the warmer compartment rise to an unsafe temperature. Furthermore, in certain types of two temperature systems, the warmer evaporator may operate below freezing and collect frost, thusreducing its effectiveness and also lowering the relative humidity in the warmer compartment in which it is desirable to maintain a fairly high relative humidity. Furthermore, a certain amount of the thermal storage capacity of the warmer evaporator may be lost.

- In accordance with my invention, therefore, in

normal operation preferably when the colderevaporator does not require refrigeration, I have devised various schemes for operating the fan after the condensing unit "has shut down, preferably independently of the air temperature in the warmer compartment. For example, the fan may be operated after the condensing unit shuts down until a predetermined high temperature of the 50 warmer evaporator is reached, or means may be employed for periodically stirring the air in the warmer compartment after the condensing unit has been shut down or the fan may run continuously regardless of the temperature of the 55 warmer compartment or warmer evaporator until the, colder evaporator or compartment requires refrigeration.

Accordingly, itis a further object of my invention to effect forced circulation of air within the cooling chamber ofa refrigerator during periods when the chamber is refrigerated.

A further object of my invention is to render the air translating means in one cooling chamber of a two chamber refrigerator inactiveduring periods when the other chamber calls for cool- 10 mg.

A still further object of 'my invention is to effect circulation of air in thecooling chamber of a refrigerator for a period of time subsequent to terminating refrigeration of the evaporator 15 therein.

Another object of the invention is to periodically eifect circulation of air in the coolingchamber of a refrigerator.

These and'other objects are efiected by my 20 invention as will be apparent-from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which: j

Fig. 1 is a diagrammatic View of a refrigerat- 25 ing system arranged in accordance with my invention; and,

Figs. 2 and 3 are diagrammatic views showing second and third embodiments of the. invention, respectively. 30

First embodiment (Fig. 1)

Reference will now be had to Fig. 1 in which I have shown a portion of a refrigerator cabinet III that includes relatively low and high tem- 35 perature cooling compartments H- and [2, respectively; Evaporator elements l3 and I4 abstract heat from the compartments .II and l2 and receive refrigerant from a common condensing unit shown at IS. The condensing unit I5 40 includes a compressor l6 driven by a motor IT. The condensing unit l5 also includes a condenser l8 cooled in any suitable manner, such as,'for example, by a motor driven fan I9.

Condensed refrigerant is conveyed from the condenser l8'to the evaporators l3 and by a conduit 2! in which a conventional high side float valve 22 may be connected. The charge of refrigerant in the system is such that liquid refrigerant substantially fills both evaporators l3 and-l4. The system operates on the compressorcondenser-expander cycle in which the compressor unit l6 withdraws vaporized refrigerant from the evaporators l3 and I4 through a conduit 23 fand compresses it to a relatively high pressure prior to its delivery to the condenser l8. The high pressure gas is cooled'and condensed in the condenser l8 and then passesto the float valve 22. The pressure of the liquid refrigerant is reduced as it passes through the float valve 22 to the evaporators I3 and I4, wherein it is vaporized at low pressure forabstracting heat from the evaporators.- This cycle continues repeatedly during the period that the compressor l6 operates. e

The evaporator |3 may be employed forfreezing fluids contained in trays 24 and for cooling the air' in chamber II to a relatively low temperature. The evaporator |4 cools the air in the chamber l2 in which articles of food or other perishables may be stored. Suitable means such as, for example, a fan 25 driven by a motor 26 isemployed for providing forced circulation of air in the chamber |2, whereby a relatively high rate of heat transfer between the air therein and the evaporator I4 is effected. During periods when the fan 25 is inactive, the rate of heat transfer is low so that refrigeration of the body of'air in the chamber 2 is not effected to any material degree. Some limited cooling of the air is effected in the chamber |2- during inactive periods of the fan 25 due to thermally induced air currents but it is relatively small. Ac-

cordingly, effective refrigeration of the air in the compartment |2 accompanies operation of the fan 25 and, during inactive periods of the latter, effective refrigeration ceases. The evaporators |3 and H are cooled by refrigerant vaporized in each at a substantially equal pressure at any one time and cool the media in their respective compartments to different temperatures due to the difference in the rate of heat transfer be-- tween the respective evaporators and the media cooled thereby.

The temperature prevailing in the chamber II is controlled by a thermostat 21, shown by way of example, of the gas type and including a bellows 28 connected by a tube 29 to its temperature responsive bulb 3|. As is well understood, the bulb of a gas type thermostat contains a suitable volatile fluid, the pressure of which is a function of its temperature. Accordingly, the bellows 28 expands and contracts as the temperature of the bulb 3| increases and decreases. Preferably, the bulb 3| responds directly to the temperature of the evaporator l3, being secured thereto as shown but it will be understood that it may be disposed otherwise in the chamber II. A lever 32, pivoted at 33, is actuated by the bellows 28 and carries movable contacts 34 and 35 of a pair of switches '36 and 31, respectively,

which switches include stationary contacts 38 and 39.

The temperature of the air in the chamber I2 is controlled by a bimetal thermostat 4|, but which may be of any suitable type. It includes an expansible bimetallic member 42 that carries a movable contact 43, the latter being engageable with a stationary contact 44 for defining a switch structure 45. The controlling operation of the thermostats 21 and 4| will be referred to hereinafter.

The source of power for the various elements of my improved apparatus is represented by line conductors L1 and L2. The compressor motor I1 is connected directly to conductor L2 and to the conductor Li'by means of a conductor 46 controlled by the switch 36 of the thermostat 21. Accordingly, when the temperature of the evaporator l3 rises to a predetermined value, the motor I1 is energized by the foregoing circuit and One termi-' the switch 31 of thermostat 21, and having a thermally actuated device 49 connected therein.

The construction of the device 49 will now be described.

Included in the elements of the device 49 is a heat responsive member or disk 5|, preferably of bimetal construction and defining the bridging member of a switch structure 52 having stationary contacts 53. The disk 5| is so constructed that it snaps into engagement with the contacts 53 when its temperature attains a predetermined high value and snaps to a circuit opening position out of engagement with the contacts 53 when its temperature is reduced to a predetermined value. The device 48 may be disposed in any suitable location, preferably, ex-

terior of the cooling compartments II or 2. A

relatively high resistance 54 is bridged across the contacts 53 and is'shunted during periods when the disk 5| bridges the contacts 53, whereby the resistance 54 is deenergized. In the open position of the switch 52, the resistance 54 is energized for heating the disk 5|.

Accordingly, when the switch 31 of thermostat 21 is closed, the resistance may be energized by a circuit'including conductor L1, closed switch 31, conductor 48, resistance 54, fan motor 25, and

conductor L2. The heated disk 5| snaps to a circuit closing position after a predetermined period of time andenergizes the fan motor 26. Air is then circulated in the high temperature chamber |2. As the heater 54 is shunted by the disk 5|, it cools and, after a predetermined period of time, the disk snaps to its open position and the fan 25 and motor 26 stop. The resistance 54 is then heated and this periodic cycling of the fan motor 28 continues as long as switch 31 is closed.

A second resistance 55 of relatively low value is disposed in heat transfer relation with the disk 5| and is connected in the conductor 41,

controlled by the higher temperature thermostat 4|. When the compressor motor I1 is energized by the thermostat 4|, including conductor 41, the resistance is connected in series with themotor l1 and, therefore, heats the disk 5| sufllciently to close the switch 52 and continuously energize the fan motor,26. Therefore, during periods when the high temperature thermostat 4| calls for cooling, the fan 25 is operated to continuously effect forced circulation in the chamber 2. Circulation of air in the chamber l2 for a period of time subsequent to the opening of thermostat 4| is effected, due to the heat stored in the disk 5| by the resistance 55.

The device 49, therefore, functions to effect forced circulation in the chamber l2 during periods when its thermostat 4| calls for cooling and to periodically effect air circulation during periods when both thermostats 4| and 21 are satisfied. During periods when the thermostat 21 calls for cooling,'the fan motor 26 is deenergized,

as the switch 31 is open.

Operation of Fig. 1 I The position of the apparatus shown in Fig. 1

indicates that the temperatures prevailing in the are satisfied. In this position, the fan 25 is periodically operated by the motor 26 to effect circulation of air inthe chamber I2, due to the closure of switch 31 and the aforementioned cycling of the device 49. This operation keeps the air stirred in the chamber l2 whereby more even temperatures prevail throughout.

Due 'to heat load in the chambers II and I2, the pressure and temperature of both evaporators l3 and 4 rise. As the temperature of the evaporators rises to a predetermined value, the thermostat 21 operates to call for cooling, whereby the switches 36 and 31 close and open, respectively. The former eflects operation of the condensing unit |5 as themotor I1 is energized as described heretofore. The fan 25 is rendered inactive to'efiect circulation of air in the compartment |2 due to the opening of switch 31.

The condensing unit l5 operates to translate refrigerant to the evaporators' l3 and M for vaporization therein. Refrigeration of the chamber II is effected and, while the temperature of the evaporator I4 is depressed to a low value, refrigeration of the air in chamber I2 is not effected to any material degree due to the inactivity of'the fan 25 and the resultant poor rate of heat transfer between the air and the evaporator I4. As the temperature of the evapcrators I3 and |4 is depressedto the value at which the thermostat 21 is satisfied, the switch 36 is opened and the switch 31 is closed. Opening of switch 36 terminates operation of the condensing unit l5 and closing of the switch 31 conditions the circuit for operation of the fan motor 26.

Assume the temperature of the air in compartment 2 rises, to the value at which the thermostat 4| calls for cooling, and that the thermostat 21 is satisfied. The switch 45 closes and energizes the compressor motor winding |1 through the circuit including conductor 41 and resistor 55. Circulation of refrigerant is initiated and continuous operation of the fan 25 is effected due to the heating of disk 5| by resistor 55, previously described. A high rate of heat transfer between the air in compartment l2 and the evaporator I4 is effected and cooling of the air incompartment I2 is obtained. At this time, the majority of refrigerant circulated is vaporized in the evaporator l4 due to the high heat load thereon.

During periods when both chambers II and |2 require cooling, the colder chamber v|| takes preference over the warmer chamber |2 as the switch 31 of the thermostat 21 is open for rendering the motor 26 and the fan 25. inactive. Refrigeration of chamber II is, therefore, effected in preference to chamber I2. After the chamber II is satisfied, control of the fan 25 and the condensing unit is assumed by the thermostat 4|, as is well understood.

Second embodiment (Fig. 2) In the showing of the second embodiment of my invention (Fig. 2), I have, for the sake of though the motor |1 of the latter is shown. Elements shown which are common to both embodiments are indicated by the same numerals.

In the present embodiment, I show a thermostat 6| of the gas type having its bulb 62 disposed in heat transfer relation with the air in the chamber 2. The thermostat 6| actuates a movable contact 63 into engagement with stationary contacts 64 and 65 in response to a predetermined high temperature of the air-in the compartment l2 and disengages the same in response to a predetermined lowtemperature oi the air. The contacts 63, 64 and 65 define a switch structure 66. The movable contact 63 is connected to the line L1 and the contact 64 is connected to a conductor 61 extending to one terminal of the fan motor 26. and controlled by the switch 31 of the thermostat 21. The contact 65 of the thermostat 6| is connected to a conductor 68 extending to one side of the winding l1 of the compressor motor and may include an inductive reaetance 69, the purpose of which will be referred to hereinafter. The other ter-' minals of the fan motor 26 and compressor motor H are connected to the line L2, as shown.

A condensing unit (not shown) similar to that shown in Fig. 1 is controlled by the switch 36 of the thermostat 21 which switch is connected in ,a conductor 1| extending from line L1 to the motor winding I1. A resistor 12 disposed in heat transfer relation with a thermo-responsive disc 13 is connected in the conductor 1| and is heated incidental to the energization of the motor winding H by the switch 36. The disc 13 is disposed in heat transfer relation with the evaporator l4 and operates to bridge stationary cuit extending from line L1 to the fan moter 26.

When the evaporator I4 is below a predetermined temperature, for example, 35 F., the contacts 14 are bridged by the disc 13 and the fan motor 26 operates to circulate air within the chamber I2. The fan motor 26 may be deenergized by the disc 13 when it is actuated to open contacts 14 in response to an evaporator temperature above 35 F. The disc 13maybe actuated in an opening direction independently of the temperature of the evaporator l4 by means of the resistor 12 when energized.

Operation of Fig. 2

The position of the apparatus, as shown,'indimand cooling. Both thermostats 21 and 6| are satisfied and, therefore, their respective switches 36 and 66 are open. The condensing unit is idle at this time. In this position, the fan may or may notbe operating, dependent upon whether temperature of the evaporator I4 is above or below 35 F. If it is below this value, the disc 13 bridges the contacts 14 and the fan 25 1s operated by its motor 26; the latter being energized by a circuit including line L1, conductor 15, mo-

tor 26 and line 1c. Accordingly, any ice formed I on the evaporator I4 is melted and the air in the, chamber I2 is circulated and cooled.

Assumethe chamber H and evaporator |3 require cooling. The thermostat 21 operates to close switch 36 and to open switch '31. Opening of the latter is of no importance for the moment as switch 66 is open. Closure of switch 36,'however, energizes the conductor 1|, heater 12 and the compressor motor winding I'I. Circulation of refrigerant by the condensing unit is initiated and the fan 25 is rendered inactive due to the opening of the contacts 14 by the heated disc 13. Refrigeration of the chamber II is effected as described heretofore in connection with Fig. 1.

As the temperature of the evaporator I3 is depressed to the desired value, the thermostat 21 moves to its satisfied position, whereby the condensing unit is stopped and the heater l2 deenergized. As the temperature of the evaporator H is relatively low, the disc closes the contacts H and the fan '25 operates to circulate air for melting any accumulated frost on the evaporator l4.

Assume that the temperature of the air in the chamber l2 rises to the predetermined value at which the thermostat 6| moves to its switch closed position and that the thermostat 21 is satisfied. The condensing unit is operated as its motor winding I1 is energized by a circuit including the line conductor L1, movable contact 63, contact 65, reactance 69, conductor 68, winding I1 and line conductor L2. The fan motor 26 is energized by a circuit including line conductor L1, contacts 63 and 64, conductor 61, closed switch 31 of the thermostat 21, fan motor 26, and line conductor L2. The air in the chamber -I2 is, therefore, circulated and cooled as described, heretofore. As the temperature of the air in the chamber I2 is depressed to the desired value, the thermostat 6! is actuated to the position shown, whereby operation of the condensing unit is terminated. The fan 25 continues operation, however, as its motor 26 continues to be energized due to the bridging of the contact H by the cold disc 13. 'Ihefan 25 stops operating when the temperature of the evaporator l4 and disc 13 rise to the assumed value of 35 F.

In the event of a demand for cooling from both compartments, the condensing unit will be operated by the preferred thermostat 21 in the manner described heretofore so that refrigeration of the cold compartment II is effected and the fan 25 is inactive. At this time, the motor winding I1 is connected to the line con-.- ductor L1 through parallel circuits, one of which includes the heater or resistance 12 and the other of which includes the reactance 69. Accordingly, current flows in the conductor H and resistor 12 due to the voltage drop across .the reactance 69, so that the fan 25 is rendered inactive by the heated disc 13 as described. When the thermostat.2'| becomes satisfied, control of the condensing unit l5 and fan 25 is assumed by the thermostat 6L.

Third embodiment (Fig; 3)

In the third embodiment of my invention as shown in Fig. 3, certain parts shown in Fig. 1 are removed for the sake of clearness and elements appearingin the present embodiment which tive when the latter calls for cooling of the chamber I l and is active at all other times. 7 One terminal of the motor 26 is connected to the line conductor. L1 and the other to a conductor 11 leading to the line 'conductor L2 and controlled by the switch 31.

The winding of the compressor motor II has one terminal connected to line conductor L2 directly and the other to a conductor 18. The

l2, to its circuit closed posito circulate air in the chamber I2 and to remove frost from the evaporator l4. As the thermostat 21 calls for cooling; the fan is rendered inactive by the opening of the switch 31 and the winding oi the. compressormotor I1 is energized by the closure of switch 36. Accordingly, refrigerant is circulated for vaporization. in the evaporators l3 and I by the condensing unit. When the temperature of the evaporator I3 is depressed to the desired value, the thermostat..21 is actuated to the position shown so that circulation of refrigerant is terminated and circulation of air in the chamber l2 initiated.

When the thermostat I9 calls for cooling, the condensing unit is started and, as the fan is operating, -refrigeration of the circulating air in the chamber I2 is effected. As described heretofore, the rate of heat transfer is high at this time so that the major portion of the circulated refrigerant is vaporized inthe evaporator I4. The refrigerant condensing unit is stopped when the thermostat 19 becomes satisfied but circulation of air in the chamber I2 is continued. During demands for cooling from both thermostats 21 and 19, the former controls, as the fan 25 is stopped by the open switch 31 at this time.

From the foregoing, it will be apparent that T have provided improved refrigerating apparatus having separately refrigerated compartments, wherein the compartments are selectively refrigerated, with provisions for refrigerating one compartment in preference to' the other. Furthermore, my improved apparatus provides for forced circulation of air in a chamber during refrigeration thereof and for a period of time subsequent thereto. The invention provides for circulation of air in cycles during inactive periods of the refrigerant circulating means and for controlling circulation of air in accordance with the temperature of the evaporator cooling the air.

I have shown my improved apparatus having the low temperature element refrigeratedin preference to the higher temperature element, when both require cooling, but it is to be understood that the higher temperature element may be given preference without departing from the spirit of my invention. Refrigerating machinesv other than the compression type shown may be departing from the spirit thereof, and I desire; therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. In refrigerating apparatus, the combination of means defining first and second cooling chambers, an evaporator element associated with each of thechambers, mea'nsfor circulating refrigerant through th'evaporator elements,.means responsive to the temperature in one of the chambers for controlling the refrigerant circulating means, means for translating air in heat transfer relation with the evaporator element in the other chamber, and means responsive to the operation of said temperature responsive, means and operative'for rendering said air translating means ineffective during periods when the temperature responsive means'calls for cooling.

2. In refrigerating apparatus, the combination of means defining first and second cooling chambers, an evaporator element associated with each of the chambers, means for circulating refrigerant through the evaporator elements, first and second means responsive to temperatures pre vailing in the first and second chambers, respectively, for controlling the operationof the refrigerant circulating means, a fan for translating air in heat exchange relation with the evaporator element in one of the chambers, and means responsiveto the operation of the temperature responsive means associated with the other of said chambers for rendering the fan inactive during periods when the'temperatureresponsive means associated with the other chamber is calling for operation ofthe refrigerant circulating means.

3. In refrigerating apparatus, the combina- I tion of means defining first and second cooling chambers, an evaporator associated with each of the chambers, means for circulating refrig-' erant through the evaporators, means responsive to predetermined high and low temperatures obtaining within the first chamber for starting and stopping the refrigerant circulating means, a fan for translating air within the second chamber in heat transfer relation with the evaporator tlierein, means responsive to predetermined high and low temperatures obtaining within the second chamber for respectively initiating and terminating operation of the refrigerant circulating means, means for effecting operation of the fan during periods when said second chamber re-- quires cooling and said first chamber is satisfied, and means responsive to the operation of the temperature responsive means associated with the first chamber for rendering said fan. inactive during periods when said first chamber requires cooling. I

4. In refrigerating apparatus, the combination of a cabinet having a cooling compartment therein, an evaporator for cooling the air in the compartment, means for translating air within the compartment in heat transfer relation with the evaporator, means for circulating refrigerant through the evaporator, means responsive to a translating means for predetermined periods of time during periods when the refrigerant cirresponsive to predetermined high and low tem-' peratures prevailing in the first chamber for initiating and terminating operation of the refrigerant circulating means, means responsive to a predetermined high temperature prevailing in the second chamber for initiating operation of the refrigerant circulating means and said fan, said last-mentioned means being effective in response to a predetermined low temperature obtaining in the second chamber for terminating operationof the refrigerant circulating means, and means for terminating operation of the fan subsequent to termination of operation of the refrigerant circulating means by said secondmentioned temperature responsive means.

6. The combination as claimed in claim 5 having means operative during periods when the first-mentioned temperature responsive means calls for operation of therefrigerant circulating means, for rendering the fan inactive irrespective of demands for its operation by the second-mentioned temperature-responsive means.

'7. In refrigerating apparatus, the combination of means defining relatively high and low temperature cooling chambers, an evaporator element arranged within each chamber, a refrigerant compressor for supplying condensed re- .frigerant to the evaporator elements-for vaporization therein, first and second thermostats responsive to temperatures prevailing in the low and high temperature chambers, respectively,

said thermostats being effective in response toconditioning the fan for operation during periods when the thermostat is satisfied andfor rendering the fan incapable of operation when the thermostat is calling for cooling, means for operating the fan during periods when the second thermostat calls for cooling and when the fan is conditioned for operation, and means forperiodically operating the fan duringperiods when both of saidthermostatsare satisfied.

' 8. In a refrigerating system having first and second chambers to be refrigerated, first and second evaporators for cooling the air in said [v chambers, respectively, means for circulating refrigerant through the evaporators, a fan for translating the air within the second chamber in heat transferring relation with its associated evaporator, means responsive to a predetermined temperature in the secondchamber for initiating operation of the refrigerant circulating means, means effective when the temperature of the evaporator in the second chamber is below a predetermined value for effecting operationof the fan, means responsive to a predeterminedtemperature in the first chamber for initiating operation of the refrigerant circulating means, and means-for rendering the fan inactive during periods when the temperature responsive means in the first chamber is calling for cooling.

9.-In a refrigeratingqsystem, the combination of means defining a chamber to be cooled, an evaporatordispo's'ed for'cooling the air in the chamber, means for circulating refrigerant through the evaporator, a fan for translating air within the chamber in heat transfer relation with said evaporator, means responsive to a predetermined high temperature within the chamber for initiating operation of the refrigerant circulating means and the fan, said temperature responsivechamber, means for circulating refrigerant through the evaporator, a fan for translating air within the chamber in heat transfer relation with said evaporator, means responsive to predetermined high and low temperatures within the chamber for respectively initiating and terminating operation of the refrigerant circulating means, and means responsive to a predetermined high and low temperature of the evaporator for respectively terminating and initiating operation of the fan.

11. In refrigerating apparatus, the combination of means defining first and second chambers, an evaporator structure having first and second portions disposed for cooling the air in the first and second chambers, respectively, means for circulating refrigerant through the evaporator, a fan for circulating air within one of the chambers in heat transfer relation with its associated evaporator portion, means responsive to predetermined high' and low temperatures of the evaporator portion in the other chamber for starting and stopping operation of the refrigerant circulating means, means for rendering said fan inactive during periods when said temperature responsive means effects operation of the refrigerant circulating means and for conditioning the fan for operation during periods when operation of the refrigerant circulating means is stopped, and means responsive to the temperature of the second evaporator portion for controlling the operation of the fan during periods when it is conditioned for operation.

12. In refrigerating apparatus, the combination of means defining first and second chambers, an evaporator structure having first and aisaoso second portions disposed for cooling the air in the first and second chambers, respectively, means for circulating refrigerant through the evaporator portions, a fan for circulating air within one of the chambers in heat transfer relation with its associated evaporator portion, means responsive to a predetermined tempera- 'ture of the air in said one chamber for conditioning said circulating means and saidfan for operation, means responsive to a predetermined temperature of the evaporator portion in the second chamber for conditioning the circulating means for operation and for rendering the fan incapable of operation, and means responsive to the temperature of said first evaporator portion for controlling the operation of the fan during periods when both of said first-mentioned temperature responsive means are satisfied.

13. In refrigerating apparatus, the combination of meansdefining first and second cooling chambers, an evaporator associated with each of the chambers, means for circulating refrigerant through the evaporators, means responsive to predetermined high and low temperatures obtaining within the first chamber for starting and stopping the refrigerant circulating means, a fan for translating. air within the second chamber in heat transfer relation with the evaporator therein, means responsive to predetermined-high and low temperatures obtaining within the second chamber for respectively initiating and terminating operation of the refrigerant circulating means, and means for effecting operation of the fan at all times excepting periods when said first chamber requires cooling.

14. In a refrigerating system, the combination of means defining a chamber 'to be cooled, an evaporator disposed for cooling the air in the chamber, means for circulating refrigerant through the evaporator, a fan for circulating air within the chamber in heat transfer relation with the evaporator, means responsive to a predeter mined high temperature within the chamber for initiating operation of the refrigerant circulating means and'the fan, said temperature responsive means being effective to terminate operation of the refrigerant circulating means in response to a predetermined low temperature within the chamber, and means for terminating operation of the fan in response to a predetermined temperature of the evaporator and after operation of the refrigerant circulating means has been terminated.

LESLIE B. M. BUCHANAN.

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