US2093835A - Refrigerating apparatus - Google Patents

Description

Sept. 21, 1937. A. o. GROOMS REFRIGERATING APPARATUS 2 Sheets-Sheet 1 Filed June 30, 1934 Se t. 21, 1937. A. o. GROOMS I REFRIGERATING APPARATUS Filed June 30, 1934 2 Sheets-Sheet 2 provide a simple. practi Patented Sept. 21, 1937 S PATENT OFFICE REFRIGERATING APPARATUS Albert Oakley Grooms,

General Motors Corporation,

corporation of Delaw Kpplication June 30,

11 Claims."

ditions both for normal operation and for de- I frosting, change according to the external or room temperature. For example, when the room temperature is relatively low, it is desirable to have a higher evaporator temperature for normal operation, but for defrosting under such conditions. it is desirable to have a lower evaporator defrosting-temperature. Heretofore, no simple practical automatic means has been provided for attaining the desirable condition.

It is, therefore. an object of my invention to al, inexpensive means occupying little or no additional space for compensating the refrigerating apparatus and particularly the control means thereof for changes in the environment or room temperature;

It is a more specific object of my invention to provide a simple bimetai means to compensate the control means for changes in external tem-- perature for providing higher evaporating temperatures when the roomtemperature is relatively low'and lower evaporating temperatures when the room temperature is relatively high.

It is also a more specific object of my invention to provide bimetal-means for compensating the control means for ture to provide lower evaporator defrosting temperatures when the room temperature is relatively, low and higher evaporator defrosting temperatures when the room temperature is relatively high.

invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. l is a sectional view of a domestic refrigerator partly diagrammatic embodying myinventon:

Fig. 2 is a sectional view of shown in Fig. 1;

Fig. 3 is a sectional control means; and

Fig. 4 is a sectional view of another modified form of control means embodying my invention.

Referring to the drawings, and more particularly to Fig. l, erator cabinet iii having a food compartment 2! containing a refrigerant evaporating means 22 for cooling the food compartment 2! and also for the control means view of a modified form of changes in external temperaher objects and advantages of the present there is shown an insulated refrig- Dayton. Ohio, assignor to Dayton, Ohio, a

1934, Serial No. 733,285

freezing comestibles in the ice trays with which it is provided. The evaporator 22 is supplied with liquid refrigerant by a refrigerant liquefying apparatus 23 including a compressor 24 for compressing the refrigerant and for forwarding the compressed refrigerant to a condenser 25 where the compressed refrigerant is liquefied and collected in a receiver 26. From the receiver 26, the liquid refrigerant is forwarded through a liquid conduit 21 to an expansion or other suitabletype of control valve 28. This valve 28 controls the supply of liquid refrigerant into the evaporator 22. The evaporator 22 evaporates the liquid refrigerant which is returned to the compressor through the return conduit 29.

The compressor 24 is driven by an electric motor 30 which is supplied with electric energy through an electric circuit 3|. Within the electric circuit 3! and in series with the electric motor 30 is a control means 32 which is operated by the thermostatic bulb 33 located in heat exchange relation with one of the walls of the cooling unit 22. The control means 32 is connected to the thermostatic bulb 83 by the tubing 34. The control means is located outside of the food compartment 34 beneath the ornamental top cover 35 r thecabinet which is provided with an opening 35 t the rear thereof for permitting the external air to contact with the control means. Referring now more particularly to Fig. 2 for a more detailed description of the control means, there is shown a bellows 3B which is connected to the thermostatic bulb 38 by the tubing 34. The bellows in turn is connected to operate a lever 89 pivoted to a wall of the control means upon the pivot pin 8h The lever 39 is connected by a link is provided with a set of switch contacts 53 which cooperate with a set of stationary switch contacts' it for opening and closing the electric motor circuit 3! in order to control the operation of the refrigerating apparatus. The operation of the control means is controlled by a tension coil spring 55 which is provided with a manual adlusting means $3 for regulating the temperature at which the contacts 63 and M are opened and closed.

with such an arrangement, it will be understood that the temperature of the evaporating means will be maintained between given temperature limits for any particular setting of the adjusting means 66. Thus, if the external or environment temperature becomes warm, more heat will flow through the insulated walls of the cabinet into the food compartment 2!. If the M to a snap acting mechanism 62 which I temperature of the food compartment becomes lower the evaporator temperature. It is also true that when the room temperature is lowered, the

lower than necessary for proper food preservation because less heat enters the food compartment and this smaller amount of heat can be absorbed by the evaporator or cooling unit at a lower temperature differential between the temperature of the food compartment air and the evaporator surfaces because the rate of heat supply is less. Thus, in order to maintain the same food compartment temperature under these conditions, it is necessary that the evaporator temperature limits be increased.

In order to lower the evaporator temperature automatically when the external or room temperature is warm and to increase the evaporator temperature when the room temperature is low, I provide a bimetal means having an upper strip 5| of iron or some other suitable material, and a lower strip of brass 52 which is riveted at one end by the rivets 53 to the lever 39 and which is connected at its opposite end to the link M which connects to the snap acting mechanism 42. The control means is surrounded by air of room temperature and has the apertures 68 in the housing or walls of the control means so that when the room or external air temperature is higher, this temperature will eifect the bimetal strip 50 and cause it to curl upwardly. This will cause the switch contacts 43 and 44 to be opened and closed at lower evaporator temperatures in order to maintain the evaporating means at a lower temperature. When the room temperature becomes colder, the bimetal strip 50 will curl downwardly and thus require higher temperatures in the bulb 33 and a greater expansion of the bellows 38 in order to move the contacts 43 and 44 to closed position. This will cause the evaporator to be maintained between higher temperature limits when the room temperature is lower.

In my control means, I have also provided a periodic automatic defrosting means for periodically increasing the temperature of the evaporat ing means to cause any frost to melt from its surfaces. This is provided by a ratchet wheel which is mounted upon the end of the switch lever 39 and which is rotated a step at'a time by the stationary resilient pawl 56. The switch lever is also provided with a spring pressed pawl 51 for controlling the direction of rotation of the ratchet wheel 55. The ratchet wheel 55 is provided with a projection 50 which, once every revolution, engages a resistance device which resists the movement of the switch mechanism toward the closed circuit position so as to cause a higher evaporating temperature before the switch contacts may be moved to closed positions.

It has been found that defrosting may be accomplished at a lower temperature when the room temperature is lower because the evaporator warms up more slowly and more uniformly under such conditions. In order to take advantage of this, I incorporate a bimetal comp ng means in my resistance device responsive to external or room temperatures which reduces the amount of additional resistance provided by the defrosting means when the room temperature is lowered. This bimetal means takes the form of a bimetal strip having an upper strip SI of brass and a lower strip 62 of iron which is pivoted upon the pivot pin 63 and yieldingly held against a fixed stop 64 by the compression type coil spring 65 which is provided with an adjusting screw 69 for varying its tension. The opposite end of the bimetal strip 60 is-provided with an adjusting screw 66 which engages the projection 58 for providing the additional resistance for defrosting and which may be adjusted so as to vary the additional resistance provided and thereby to vary the defrosting temperatures.

Once every revolution of the ratchet wheel 5|, the projection comes up and engages the lower end of the adjusting screw 56. Further upward movement of the switch lever 39 is resisted by the bimetal strip 00 and the tension spring 65. When the external or room temperature is lowered, the bimetal strip 00 will curl upwardly, thus moving the adjusting screw 56 upwardly slightly and reducing the resistance provided by the defrosting mechanism. This will require a lesser force and a lower temperature in order to move the switch contacts 43 and 44 to closed circuit position. In this way, a lower defrosting temperature is provided when the external temperature is lowered.

In Fig. 3, I have shown a modified form of control means in which the bimetal compensating means is made adjustable. In this form, generally designated by the reference character I03, is the bellows I38, which is connected by the tubing I 34 to a thermostatic bulb which is mounted upon and in heat exchange relation with the evaporator within the food compartment. The bellows I38 operates the lever I39 under the control of a tension coil spring I45 which is provided with an adjusting screw I46. The free end of, the lever I39 is connected to a snap acting toggle type of switch contact mechanism I42 for opening and closing the switch contacts I43 and I44. The housing or walls of the control means are provided with apertures I68 for permitting the circulation of external or room air through the control means.

In order to compensate the switch means and the temperature limits of the evaporator for changes in the external or room temperature, I provide a bimetal strip I50 which is fastened at one end by the rivets I53 to a block fixed to the housing or walls of the control means. This bimetal strip has an upper strip I52 of iron and.

a lower strip I5I of brass. An a justing screw I 55 extends through the lever I 9 and contacts and imposes a bending movement on the bimetal strip I50. By moving this adjusting screw I55 upwardly or downwardly, the tension exerted by the bimetal strip I50 upon the lever I39 may be adjusted. When the external or room temperature becomes lower, the bimetal strip I50 will tend to curl downwardly and increase the resistance to the expansion of the bellows I38 and thus control the operation of the compressor of the refrigerating system so as to maintain a higher temperature in the evaporator. When the external temperature becomes warmer, the bimetal strip I50 will tend to curl upwardly thus reducing the tension imposed upon the lever I39 and making it more easy for the bellows I38 to expand and move the switch contacts to closed circuit position to cause operation of the motor com- Thus, in this form. the switch pressor unit. means is compensated by an adjustable bimetal resistance means.

In Fig. 4, I have shown another modification embodying a double toggle switch mechanism, the arms of which are formed of bimetal strips. In this form, generally designated by the reference character 204, there is provided a metal bellows 238 connected by the tubing 234 to athermostatic bulb which is mounted upon and in heat exchange relation with the cooling unit or evaporator of the refrigerating system. The bellows 238 operate a primary lever 239 under the control of a tension coil spring 245, the tension of which may be adjusted-by an adjusting screw 246. The primary lever 239 is provided with an insulating block 210 which is provided with notches to receive the knife edges at one end of a secondary lever ZH which has its opposite or free end connected by a tension coil spring 212 to a post 2113 formed on a bimetal arm or strip 21% of the bell crank contact lever 215. This bell crank contact lever 275 is pivoted upon the pin 276 to an insulating portion 21'! forming a part of the wall of the housing of the control means 204. This bell crank lever also has stop portions 218 and 219 which limit the movement of the free end of the secondary lever 2H.

The bell crank lever N5 is provided with, a second bimetal arm or strip Eddwhich carries a switch contact 2% at its lower end which cooperates with and is adapted to engage a stationary contact 282 which is mounted upon a second insulating portion 288 forming part of the wall of the housing of the control means 2%. 1 The housing of the control means 266 is provided with apertures Zed which provide for a circulation of external air from the room into heat exchange relation with the bimetal strips or arms 2'86 and 288. The bimetal strip or am 21 3 has an upper strip Edd of brass and a lower strip 286 of iron or other suitable material, while the bimetal arm or strip Md-has a strip 2% of iron and a strip ml of brass. It should be noted that in this arrangement, the two closer strips in the arms are of iron while the strips furthest away are of brass. This causes the arms to move closer together when the external temperature is warm, thereby reducing or lowering the cut-out temperature which controls the stopping of the refrigerating apparatus, but without effecting the cut-in temperature which controls the starting of the re frigerating apparatus and which is adjusted by the stop screw 2% which serves as the difierential adjustment.

When the external or room temperature is colder, the bimetal arms tend to curl away from each other and thus to raise the cut-out temperature or temperature at which the reirigerah.

ing apparatus is stopped. The changing of the cut-in and cut-out temperatures by the bimetal arms and the differential adjusting screw 290 is accomplished by varying the angularity of the bell crank lever Elli at the time at which the con tacts are moved to open or closed position. This changing of the angularity, changes the angularity ofthe secondary lever 218 with respect to the primary lever its at these tripping points and thereby varies the temperatures at which the opening and closing occurs. Thus, in this form, the bimetal compensating means acts merely to vary the cut-out point or the stopping ture of the refrigerating apparatus.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred temperaform, it is to be understood that other forms might be adopted, all/coming within the scope of the claims which follow.

What is claimed is as follows:

1. Refrigerating apparatus-including an insulated cabinet having a compartment to be cooled, a cooling means inheat exchange relation to said compartment to compartment, compressing and means for supplying medium to said cooling means, pressure operated means dependent upon the temperature of the cooling means for controlling said compressing means, and bimetal means thermally responsive to temperatures outside of said compartment for applying a resilient force for the operation of said controlling means.

2. Refrigerating apparatus including an insulated cabinet having a compartment to be cooled, a cooling means in heat exchange relation with said compartment to be cooled for cooling said compartment, compressing and. condensing means for supplying cooling medium to said cooling means, means dependent upon the temperature of the cooling means for controlling said compressing means to normally maintain said cooling means at freezing temperatures, auxiliary means adecting the control of the compressing means for temporarily providing temperatures of the cooling means above freezing, and bimetal means responsive to temperatures outside of said compartment for regulating the temperatures provided by the auxiliary means.

, 3. Refrigerating apparatus including an insulated cabinet having a compartment to be cooled, a cooling means in heat exchange relation with said compartment to be cooled for cooling said compartment, compressing and con densing means for supplying cooling medium to said cooling means, means,dependent upon the temperature of the cooling means for controlling said compressing means said cooli means at freezing temperatures, auxiliary means affecting the control of the compressing means for porarily providing temperatures of the cooling means-above freezing and thereafter resng normal temperature control of the cooling means, and means responsive to temperatures pertinent for regulating the temperatures provided by the auxiliary means without aifecting the normal control cooling unit.

4. Refrigerating apparatus including an insulated cabinet having a compartment to be cooled, a cooling means in heat exchange relation with said compartment to be cooled for cooling said compartment, compressing and condensing means for supplying cooling medium to said cooling means, means dependent of the cooling means for controlling said compressing means to normally maintain said cooling means at freezing means for periodically affecting the control of the compressing means for providing temperatures'oi' the cooling means above freezing and thereafter resuming the normal temperature control of the cooling means, and means responsive to the temperatures outside of said compartment for regulating the temperatures provided by the periodic means.

5. Refrigerating apparatus including anin sulated cabinet having a compartment to be cooled, 'a cooling means in heat exchange relation to said compartment to be cooled for cooling said compartment, compressing and condensto normally maintain outside of said com= upon the temperature teratures, periodic be cooled for cooling said condensing as J control casing containing ing means for supplying cooling medium to said cooling means, said compressing means including an electric motor and an electric circuit for supplying electric energy thereto, a set of switch contacts in series with said electric circuit for controlling the supply of electric energy, pressure means dependent upon the temperature of the cooling means, and bimetal means connecting the pressure means and the switch contacts for opening and closing the switch contacts.

6. Refrigerating apparatus including a cooling unit for cooling a medium and a circulating unit for circulating refrigerating medium through said cooling unit, a control means including a control casing containing pressure operated means dependent upon the temperature of the cooling unit for controlling the circulating unit, said casing also containing bimetal means thermally independent of said dependent means responsive to temperatures within the casing for applying a yielding force to the control provided by said dependent means.

7. Refrigerating apparatus including a cooling unit for cooling a medium and a circulating unit for circulating refrigerating medium through said cooling unit, a control means including a control casing containing pressure operated means de-.

pendent upon the temperature of the cooling unit for controlling the circulating unit, said casing being mounted within a medium surrounding and in contact with the medium surrounding one of said units of the refrigerating apparatus, said casing being provided with ventilating apertures, said casing also containing bimetal means for applying a yielding force to the control pro vided by said dependent means.

8. Refrigerating apparatus including a cooling unit for cooling a medium and a circulating unit 'for circulating refrigerating medium through said cooling unit, a control means including a pressure operated means dependent upon the temperature of' the cooling unit for controlling the circulating unit,

said casing also containing bimetal means in the form of a cantilever operably connected to said dependent means for applying a yielding force to the control provided by said dependent means.

9. Refrigerating apparatus including a cooling I unit for cooling 9. medium and a circulating unit for circulating refrigerating medium through said cooling unit, a control means including a control casing containing means dependent upon the temperature of the cooling unit for controlling the circulating unit for normally maintaining the temperature of the cooling unit within predetermined limits, auxiliary means for temporarily disrupting said temperature limits, and means responsive to temperatures within said casing for modifying the effect of said auxiliary means without affecting the normal control of the temperature of the cooling unit.

10. Refrigerating apparatus including a cooling unit for cooling a medium and a circulating unit for circulating refrigerating medium through said cooling unit, a control means including a control casing containing means dependent upon the temperature of the cooling unit for controlling the circulating unit for normally maintaining the temperature of the cooling unit within predetermined limits, auxiliary means for periodically disrupting said temperature limits, and means responsive to environment temperatures of one of said units of the refrigerating apparatus for modifying the effect of said auxiliary means.

11. Refrigerating apparatus including a cooling unit for cooling a medium and a circulating unit for circulating refrigerating medium through said cooling unit, a control means including a control casing containing means dependent upon the temperature of the, cooling unit for-controlling the circulating unit for normally maintaining the temperature of the cooling unit. within predetermined limits, auxiliary means for temporarily disrupting said temperature limits, and bimetal means responsive to temperatures within said casing for modifying the efiect of said auxiliary means.

' ALBERT OAKLEY GROOMS.

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