US2672018A

US2672018A - Two-temperature refrigerating apparatus

Info

Publication number: US2672018A
Application number: US193963A
Authority: US
Inventors: James W Jacobs
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1950-11-03
Filing date: 1950-11-03
Publication date: 1954-03-16
Anticipated expiration: 1971-03-16

Description

March 16, 1954 .1.w. JAcoBs TWO-TEMPERATURE REFRIGERATING APPARATUS 4 Sheets-Sheet 1 I IIUI .IIHHHIH IIIIIIIIIIVHH,

Filed Nov. 5, 1950 Z0] VENTOR.

March 16, 1954 W JACOBS 2,672,018

TWO-TEMPERATURE REFRIGERATING APPARATUS Filed Nov. 3, 1950 4 Sheets-Sheet 2 INVENTOR. 'f// ZU March 16, 1954 J W, JACOBS 2,672,018

TWO-TEMPERATURE REFRIGERATING APPARATUS Filed Nov. 5, 1950 4 Sheets-Sheet 5 aso'l March 16, 1954 Filed Nov. 3, 1950 J. w. JAcoBs 2,672,018

TWOTEMPERATURE REFRIGERATING APPARATUS 4 Sheets-Sheet 4 #v51/MUM 472 480 INVENTOR.

Patented Mar. 16, 1954 UNITED STATES PATENT OFFICE TWD-TEMPERATURE REFRIGERATIN G APPARATUS poration of Delaware Application November 3, 1950, Serial No. 193,963

14 Claims.

This invention relates to refrigerating apparatus and more particularly to household refrigerators in which the food compartment is refrigerated at temperatures above freezing by the evaporator in a secondary circuit which has its condenser thermally connected to a freezing evaporator in heat exchange relationship with a-freezing compartment.

It is an object of my invention to provide a snap action control for such a refrigerator which will maintain proper temperatures in the food compartment and which will provide a convenient means for defrosting the evaporator of the secondary circuit.

It is another object of my invention to provide a snap acting valve for controlling the circulation in the foodcompartment evaporator in such refrigerator to make it possible to defrost the food compartment evaporator.

It is another object of my invention to provide a combination snap acting valve and switch having a common pressure actuating means and convenient common adjusting means.

It is another object of my invention to provide a snap acting valve having a pressure responsive actuating means and the toggle means directly connected to the valve element.

It is another object of my invention to provide a pressure operated snap acting valve in a secondary refrigerant circuit which is set to automatically open and close in successive cycles during normal operation of the system.

Further objects and advantages of the present 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. 1 is a view partly diagrammatic of a household refrigerator embodying one form of my invention;

Fig. 2 is a view partly diagrammatic of a household refrigerator embodying another form of my invention;

Fig. 3 is a sectional view taken along the line 3 3 of Fig. 4 of the valve in the secondary circuit shown in Fig. 1;

Fig. 4 is a sectional view taken along the line 4-4 of Fig. 3;

Fig. 5 is a sectional view taken along the line 5--5 of Fig. 4;

Fig. 6 is a bottom of the valve shown in Figs. 3 and 4;

Fig. 7 shows a modified form of valve element A,of the valve shown in Figs. 3 and 4;

Fig. 8 is a sectional view of valve shown. in Fig. 2; and

Fig. 9 is a diagrammatic view of a household refrigerator with a combination snap acting switch and valve shown in section.

Referring now to the drawings and more particularly to Fig. 1, there is shown a household refrigerator 20 including a freezing compartment 22 and a food compartment 24 each separately enclosed with sheet metal Walls and surrounded by a thermal insulation 2S diagrammatically indicated by the dot-and-dash outlines of the cabinet structure. The refrigeration is accomplished by providing a sealed motor compressor unit 28 which forwards the compressed refrigerant to a condenser from which the liquid is conducted through a supply conduit 32 to an expansion valve or restrictcr 34 which controls the flow of the refrigerant in this primary 20 refrigerator system into the evaporating coils 36 which extend in heat exchange contact with the bottom, top, sides and back of the freezing compartment 22. The refrigerant evaporates in the primary evaporator 3B and is returned through the return conduit 38 to the compressor 28.

To insure adequate cooling for the lower part of the compartment, there is provided a first secondary refrigerant circuit having a condensing portion 40 mounted in heat exchange contact with the back wall of the freezing compartment 22 so that it is in heat exchange relation with the primary evaporator 36. A liquid supply conduit 42 extends to the bottom portion of the food compartment 24 and extends around the 35 back and sides to form an evaporating portion 44 which extends upwardly and connects to a return conduit 46 which discharges into the condensing portion 40.

In the upper portion of the food compartment, there is provided a hollow sheet metal plate 48 located adjacent the rear wall. This plate contains refrigerant passages and the uppermost refrigerant passage is connected to the condenser 54 by a return conduit 50 which extends upwardly until it reaches a point 52 which is above the level of the condenser 54. The condenser 54 is in heat exchange contact with the rear wall of the freezing compartment 22 and it drains through a liquid conduit 56 which extends to a snap acting valve 58 which may be of the type 55 Referring now more particularly to Figs. 3 7,

3 there is shown a valve body 52 having the liquid line 56 connected to enter the Valve body directly through the valve seat opening. The conduit 6U connects directly with the valve and bellows chamber within the valve body 62. Shown upon the valve seat in Figs. 3 and 4, is a valve member =64 provided witha cover 66 `of some form of synthetic rubber-like material upon a metal disc 68 which in turn is riveted to the bottom.

of the bellows 16 and to the bottom of the valve stem 12. The upper end of the valve steml 12 has threaded thereon a metal knob member 14 which is covered with the rubber boot portion of a sealing diaphragm 16 of synthetic rubber which has its heavy peripheral portion clamped in sealing engagement of the upper rim of the valve body by a gland 18.

Within the upper portion of the valve body 62, there is provided a toggle spring 80 which is semielliptic iin shape as shown in Fig. and which lhas its ends bearing against the inner surfaces of the valve body 62. Extending between this valve stem-12 and the toggle spring 86 is a toggle blade 84 having knife edges and its opposite ends which engage` `notches provided in the toggle spring llf'andwthe valve stem 12. A second toggle blade iisprovidedwith knife edges at its opposite ends engaging notches inthe valve stern 12 and a button'88 which is rotatably mounted upon an adjusting screw 96. To obtain a snap action which will'cause the valve 64 -tomove quickly from the fully'closed Iposition to the fully open position, the=adjusting screw 922i is adjusted to apply a column -loading to the toggle blades d6 and 3S and the spring 80 which provides a component in the direction of movement of the valve stem which is greaterthan any spring force in the bellows lil. A suitable seal 92 of synthetic rubber' is provided forthead-justing screw tu so that it together with `the diaphragm seal .16 will effectively yprevent the entrance 4'of external air and moisture to the interior of the valve body 62.

If it is desired that this `Valve be manually operated,the secondary circuit is supplied with refrigerant in an amount which is insufficient to fill .the liquid line v5.6 `and the condenser 54 up to -the highfpoint `5.2. With that arrangement, the :pressure `within the `secondary circuit will be governed'by the temperature of thefcondenser iid and vvill'not risesuiiciently to act on the bellows 16 to r Vopen-the valve. By increasing the amount of refrigerant `in the system until it condenses more ithanenough to ll withY liquid the conduit 56 and 4thescondenser 5d up to the high point `52, the pressure inthe sytem when the valve 58 is closed willrise-according to the temperature ofthe plate 48 until it becomes high enough to act on the bellows with sufficient force to overcome the closingcomponent of force of the togglemechanisrn upon the stern 12 to collapse the bellows Y10 and move the valve 64 to the fully open position.

If desired, this same arrangementmay be made -toautomatically open and close the valve 64 in successive cycles by marking the angularity ci theftoggle blades 8d and 86 small so that the differential is reduced. If the primary system is controlled by the switch 90. to maintain they freezing'compartment 22 in the neighborhood of 0 F.,

-the vali/e258 will for this purpose be adjusted to close upon the secondaryvcircuit having its pressure reduced to a certain low point such as a pressure equivalent to about 18 F. and maybe set -s`o that 'the valve will open when the temperature within the plate 48 reaches a value above freezing such'as 3`4`"F. The switch U4 is connected Lic in series with motor compressor unit 28 and is controlled by a thermostat bulb in heat exchange relation with an intermediate portion of the primary evaporator 36 as well as the high portion or" the secondary circuit near the point 52. This makes the switch Sli-sensitive to increases in temperature in either the freezing compartment 22 or the food compartment 24.

In Fig. 7, the bellows |10 is operatively connected to the valve 64 by a compression type coil spring |65 which `always keeps the metal upper plate 161 oi the valve member 64 in contact with the rivet l'il at the lower end of a valve stem identical to the valve stem 12 shown in Figs. 3 and 4. The valve member |64 is provided with a surface of synthetic rubber in a manner similar to the valve member 64.

In Fig. 2, there is shown a household refrigerator 22E including a freezing compartment 222 and-a food compartment 225. These are enclosed within insulation the outlines of which are illustrated by the dot-and-.dash outline 225. The refrigerator is provided with a sealed motor compressor unit 22S which compresses the refrigerant and forces the compressed refrigerant into a condenser 23d wherein the compressed refrigerant is liquefied and conducted through a supply conduit 232 to an expansion Valve or restrictor which controls the flow of liquid refrigerant to a high temperature evaporator 2M which extends arounfl the bottom, side and rear walls of the food compartment 22-1. Some of the liquid refrigerant is conducted through the supply conduit to a second valve or restrictor 235 which controls the flow of liquid refrigerant into the freezing evaporator 236 which extends about the bottom, top, side and rear walls of the freezing compartment 222. The upper ends of the evaporators 235 and 2M are connected to the snap acting valve 258 which is connected by the return conduit 260 to the sealing motor compressor unit 228.

The operation of the sealed motor compressor unit 228 is controlled by a dual thermostat switch 294 preferably of the type shown in the Grooms Patent 2,216,589 having one Athermostat bulb 293 located in the freezing compartment and the second thermostat bulb 295 located in the food compartment 224. By this dual thermostat arrangement, the motor compressor unit will operate whenever either the freezing compartment or the food compartment 224 requires refrigeration. The construction of the valve 258 is shown in Fig. 8. The high pressure, high temperature evaporator 244 connects directly into the bellows chamber 256 of the valve. The botto-m of this bellows chamber contains a valve seat 2l which is adapted to receive the valve member 264 having a covering of synthetic rubber. The valve stem 212 connects the valve member 266 to the bottom of the bellows 210.

At the upper end of the valve stem 212, there is provided a set of

toggle blades

284 and 286. The outer end of the toggle blade 284 has a knife edge which engages a notch in the semi-elliptic toggle spring 280. The outer end of the blade 286 also has a knife edge which engages a notch in the bottom 268 which is rotatably mounted in the adjusting screw 290 and the access opening to this screw 290 is sealed by a sealing member 292 of synthetic rubber. Within the bellows 210, there is provided a compression type coil spring 21| which at its lower end rests against a spring retainer mounted` upon the closed lower end .of the bellows 210. VlThe upper end of the 'compression type coil spring is supported by an upper spring retainer 213 connected by the pins 215 to a transverse connecting member 211 which is threaded upon the hollow adjusting screw 219.

This hollow adjusting screw 219 is rotatably mounted in the adjustable threaded bushing 29| which may be used for adjustably locating the screw 219. The screw 219 is provided with a convenient adjusting knob 283 for adjusting the tension of the compression spring 21| so as to determine the pressure required within the bellows chamber to collapse the bellows 219 to move the valve 264 to the open position. The adjusting screw 299 is adjusted to apply a column load to the toggle links 286 and 284 as well as to the spring 289 sufficient that the component in the direction of movement of the valve stem 212 will begreater than the force of the spring 2li and the bellows 219. This will insure snap action movement which will proceed directly from the fully closed position to the fully open position and vice versa. The closing pressure of the valve 264 is determined by the location of the adjusting screw 295 which is threaded within the interior of the hollow screw 219. The interior of this screw 219 is closed by a small screw 281 which may be removed to gain access to the screw 285 for adjusting the closing pressure. This valve mechanism so far described controls only the flow of refrigerant from the high pressure evaporator 244. By making this valve pressure responsive in this manner, the evaporating pressure and temperature within the evaporator 244 may be accurately controlled.

The opening in the valve seat 261 connects to a lower valve chamber 329 having a valve seat 322 provided in a valve cage 324 located in the valve chamber 329. This valve seat 322 is adapted to be closed by a valve member 326 having a periphery of synthetic rubber adapted to engage the seat 322 and having the center portion of metal which is adapted to be held in contact with the lower end of the valve stem extension 328 by a very light compression type coil spring 336. The valve cage 324 and the valve 326 divide the valve chamber 329 into a portion communicating directly with the return conduit 269 and the valve 264 and a portion connecting with the high pressure evaporator 236. The compression spring 339 is light enough so that it just has sufficient force to hold the valve member 326 in the closed position when the extension 328 of the valve stem 212 is in the upper position. By virtue of this arrangement, when the pressure in the freezing compartment 236 is greater than the return conduit 269, evaporated refrigerant will push the valve 326 to the open position in the manner of a check valve. This will allow the motor compressor unit to draw refrigerant from both the high pressure, high temperature evaporator 244 and the low temperature, low pressure freezing evaporator 236 when both evaporators require refrigeration. However, the valve 326 will prevent the flow of refrigerant from either -the high pressure evaporator 244 or the return .Aitellthe pressureand. temperaturev .withinths evaporator have been reduced sufciently the check valve 326 will prevent any flow of refrigerant from the high temperature evaporator 244 into the low pressure evaporator 236.

The valve 264 will close automatically and the extension 328 will force open the valve 326 thereby bringing the low pressure evaporator 236 directly in open communication with the return conduit 269 so that the motor compressor unit 228 may continue in operation to lower the pressure and temperature in the freezing compartment evaporator 236 until both compartments have their requirements satisfied. This provides a very enicient form of operation.

At the bottom of Fig. 9, there is provided a household refrigerator 429 in rear view. This refrigerator includes a freezing compartment 422 and a food compartment 424. These compartments are enclosed in insulation indicated by the dot-and-dash outline 426. A primary refrigerating system is provided including a sealed motor compressor unit 428 which discharges compressed refrigerant into the condenser 439 where the refrigerant is condensed and supplied through the supply conduit 432 to the expansion valve or restrictor 434 which controls the iiow of refrigerant to the primary evaporator 436 which extends in contact with the bottom, top, sides and rear walls of the freezing compartment 422. The liquid refrigerant evaporates in the evaporator 436 and is returned to the motor compressor unit 42S through the return conduit 438. The bottom of the food compartment is cooled by a secondary refrigerant circuit having a condenser portion 1449 in heat exchange relation with the rear walls of the freezing compartment and having an evaporating portion 444 in contact with the bottom and the lower portion of the sides and rear wall of the food compartment 424.

A second secondary refrigerant circuit is provided with a condensing portion 454 in heat exchange contact with the rear Wall of the freezing compartment and an evaporator plate 448 within the food compartment 424. This plate is similar to the plate 48. The upper portion of the plate 449 is connected to the uppermost portion of the condenser 454. The lowermost portion of the condenser 454 is connected by a liquid conduit 456 to a valve 458. This valve 459 includes a valve body 462 containing a valve seat 459. On the valve seat 459, there is provided a valve member 464 formed of a metal disc having a synthetic rubber covering covering its lower face and its periphery. A valve cage 465 surrounds the valve member 464 and is connected directly to the lower end of the valve stem 412 and the lower end of the bellows 419. Between the top of the valve cage and the top of the valve member 464, there is provided a light coil spring 461. This serves to hold the valve 464 in contact with the seat when the valve is in closed position. This provides a full iioating mounting thus insuring tight closing of the valve 464 vupon the seat 459, when the valve stem 412 is in the position shown in Fig. 9 and a positive opening.

As in the other modications, the valve stem 412 is provided with

toggle blades

484 and 486. The toggle blade 464 is provided with a knife edge at its outer end which bears against the semi-elliptic spring member 489 while the toggle blade 496 has a knife edge at its outer end which is received within the notch in the button 488. This button 469 is rotatably mounted in the adjusting screw 499 which is sealed by an insert 492, 0f. synthetic rubber.- ...This adjusting screw 490 is adjusted to appl-y a column load'gto the toggle blades 86` and #86 aswell Aas `the spring 480 suflicient to provide a component of `force in the direction of movement of the valverstem 412 which is greater than spring lforce of Athe bellows 410 and the light coil spring It?! as rwell as the switch blade 520. This insures sna-p action opening and closing of the valve member 4M.

The bellows chamber connects to the suppl-y conduitl 46|] which connects to the `bottom of the plate 448. This secondary circuit is provided with sufficient refrigerant to `flll with liquid the conduit 45B as well as `the `condenser 454 Aso that the pressure within the circuit -w-ill be vresponsive to the temperature of the plate 448 as explained in connection with the plate 68 in Fig. 1. Although in the diagrammatic view shown in Fig. 9, .the valve 458 is located above the cabinet 420. This 'location is merely used for convenience fin showing the enlarged section of thewalve and `in reality the secondary circuit is arranged in Aa manner similar to that shown in Fig. 1 and lthe valve 458 is mounted directly upon the plate `M8 in the seme way as the valve 58 ismounted upon the plate 48 in Fig. 1.

I have found that this `bellows '41!) andthe toggle mechanism can also be used to operate a switch mechanism for controlling the motor compressor unit. `'I'o do this, I have provided a connecting member 522 of electrical insulating material which connects `the valve stem 412 directly to the switch blade 525 which khas one end anchored to the terminal '5M and the other end provided with a movable switch contact 525.

This movable switch contact 52-3 is adapted -to make engagement with an adjustable contact provided upon the adjacent end ci an Yadjustable terminal 52B which is threaded 4through the switch base 530 of electrical insulating material. This switch base 530 is mounted Vupon the top of the valve body 458. The terminal 524 is connected to the supply conductor A532 while the terminal 528 is connected by the conductor 534 to the sealed motor compressor unit vM728. A second supply conductor 535 connects to the sealed unit 428.

The terminals '524 and 528 are enclosed within a .covering 538. The'switch Vbase 530 is provided with an adjusting screw 540, provided with an adjusting knob 5427, at its outer end. The inner end of the screw 540 serves as a stop to limit the upward movement of the valve stem 412. This determines the temperature and pressure `witlfiin the secondary circuit at which the valve '64 will move from open to closed position and the switch contact 525 will move from closed position to open position tok stop the operation of the motor compressor unit. The opening of the lvalve 464 and the closing movement of the switch contact 526 is adjusted by the adjusting screw 490. By this system, the plate 448 maybe operated at temperatures below freezing but before the motor compressor unit starts, it will rise above freezing temperatures so that frost will be melted from every cycle. The cost of the system `is reduced by use of `a single bellows and a single toggle mechanism to operate `and control both 'the switch and the valve.

` In accordance with the provisions of Rule 78a, reference is made to copending application S. N. 153,353 filed April 6, 1950, now Patent No. 2,611,275.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms 8 might be adopted, -aszmay-come `within the scope of the claims which follow.

What is claimed is as follows:

1. Refrigerating apparatus including an insulated household refrigerator cabinet having a freezing compartment and a food compartment, a. refrigerating system including separate evap orating means for `separately cooling each -of said compartments and a li'quefying means, a .snap action valve means connected to and in series with the separate evaporating means for .the food compartment to control `the ow Vof refrigerant, said valve means including a pressure responsive means exposed to the pressure within said separate evaporating -means for .the `food compartment and operably connected to .said snap action valve means and proportioned for opening said valve means upon the attainment of a predetermined high pressure corresponding to a temperature above freezing and for closing said valve means upon the attainment of `a predetermined low pressure corresponding V.to .a .temperature below freezing.

2. Refrigerating apparatus includingan insulated refrigerator cabinet having'a freezing Acompartment and a food compartment, a refrigerating system including separate -evaporating means for separately cooling each of said compartments and a liquefying means, a snap action valve means connected to and in series with l.the separate evaporating ymeans for the food compartment to control the ilow of refrigerant, said valve means including a pressure responsive .means exposed to the pressure within said separate evaporating means for the -food compartment and operably connected to said snap action `valve means for opening said valve means upon the attainment of apredetcrmined highpressure and for closing said valve means upon the attainment of a predetermined low pressure, and a switch means controlled by said pressure responsive means for controlling the operation of said liquefying means.

`.3. Refrigerating apparatus including Aan insulated refrigerator cabinet `vhaving Aa freezing compartment and a food ,compartment for storage above freezing temperatures, a primary refrigerating ,system including a liquefying means `located outside said compartments and aprirnary evaporating means 'located in heat exchange relation with the freezing compartment, a secondary refrigerant circuit having `a condensing means located in heat exchange relation with said primary evaporating means and a secondary evaporating means located in heat exchange relation with said `food compartment, and a temperature responsive means responsive to tem- Deratures 0f .said secondary evaporating means for starting and ,stopping the operation .of said liquefying means.

4.A Refrigerating apparatus including .a primary refrigerating system comprising liquefying means and evaporating means, .a rsecondary re frigerant circuit including a .condensing means in heat exchange .relation with the evaporating means `of said primary system and an evaporat ing means, means for shielding the evaporating means 0f the .Drimarysystem from the evaporatving means of the secondary circuit, anda pressure operated snap action valve means connected in said secondary circuit "be'tweenfthe .evaporating means and the vcondensing means, said snap action valve means having a. completely closed Position for stopping circulation in xmseeaneary circuit and an open position permitting circulation in this circuit.

5. Refrigerating `apparatus including a primary refrigerating system comprising liquefying means and evaporating means, a secondary refrigerant circuit including a condensing means in heat exchange relation with the evaporating means of said primary system and an evaporating means, means for shielding the evaporating means of the primary system from the evaporating means of the secondary circuit, and a snap action valve means connected in said secondary circuit between the evaporating means and the condensing means, said snap action valve means having a completely closed position for stopping circulation in the secondary circuit and an open position permitting circulation in this circuit, and a pressure responsive means in said secondary circuit operably connected to said snap action valve means to move the valve means from one position to another upon a predetermined change in pressure.

6. Refrigerating apparatus including a primary refrigerating system comprising liquefying means Aand evaporating means, a secondary refrigerant circuit including a condensing means in heat exchange relationA with the evaporating means of said primary system and an evaporating means, means for shielding the evaporating means of the primary system from the evaporating means of the secondary circuit, said condensing means having its inlet above its outlet, a snap action valve means connected in said secondary circuit between the outlet of said condensing means and the evaporating means of said secondary circuit, said snap action valve means having a completely closed position for stopping the iiow of refrigerant from said condensing means to the evaporating means of said secondary circuit and an open position permitting unobstructed liquid ow.

7. Refrigerating apparatus including "a primary refrigerating system comprising liquefying means Iand evaporating means, a secondary refrigerant circuit including a condensing means in heat exchange relation with the evaporating means of said primary system and an evaporating means, means for shielding the evaporating means of the primary system from the evaporating means of the secondary circuit, said cono densing means having its inlet above its outlet, a snap action valve means connected in said secondary circuit between the outlet of said condensing means yand the evaporating means of said secondary circuit, said snap action valve means having a completely closed position for stopping the flow of refrigerant from said condensing means to the evaporating means of said secondary circuit and an open position permitting unobstructed liquid iiow, said secondary circuit containing an amount of refrigerant more than sufficient to fill with liquid refrigerant the portion of said secondary circuit between said valve means and the condenser inlet.

8. Refrigerating apparatus including a primary refrigerating system comprising liquefying means and evaporating means, a secondary refrigerant circuit including a condensing means in heat exchange relation with the evaporating means of said primary system and an evaporating means, means for shielding the evaporating means of the primary system from the evaporating means of the secondary circuit, said condensing means having its inlet above its outlet, a snap action valve means connected in said secondary circuit between the outlet of said condensing means and the evaporating means of said secondary circuit, said snap action valve means having a completely closed position for stopping the iiow of refrigerant from said condensing means to the evaporating means of said secondary circuit and an open position permitting unobstructed liquid flow, said secondary circuit containing an amount of refrigerant more than sufficient to fill with liquid refrigerant the portion of said secondary circuit between said valve means and the condenser inlet, and a pressure responsive means exposed to the pressure within said secondary circuit and operably connected to said valve means to move the valve means from one of said positions to another upon a predetermined change in pressure.

9. Refrigerating apparatus including an insulated refrigerator cabinet having a freezing compartment and a food compartment, a refrigerating system including separate evaporating means for separately cooling each of said compartments and a liquefying means, a snap action valve means connected to and in series with the separate evaporating means for the food compartment to control the flow of refrigerant, said valve means including a pressure responsive means exposed to the pressure within said separate evaporating means for the food compartment and operably connected to said snap action valve means for opening said valve means upon the attainment of a predetermined high pressure and for closing said valve means upon the attainment of a predetermined low pressure, said liquefying means being connected to supply to and withdraw refrigerant from both of said separate evaporating means, a check valve connected in series with said separate evaporating means for the freezing compartment, and means responsive to the closing of said snap action valve means for positively opening said check valve.

10. Refrigerating apparatus including a primary refrigerating system comprising liquefying means and evaporating means, a secondary refrigerant circuit including a condensing means in heat exchange relation with the evaporating means of said primary system and an evaporating means, means for shielding the evaporating means of the primary system from the evaporating means of the secondary circuit, and a snap action valve means connected in said secondary circuit between the evaporating means and the condensing means, said snap action valve means having a completely closed position for stopping circulation in the secondary circuit and an open position permitting circulation in this circuit, and a pressure responsive means in said secondary circuit operably connected to said snap action valve means to move the valve means from one position to another upon a predetermined change in pressure, said pressure responsive means and the snap action of said valve means being proportioned to open said valve means when the refrigerant in said secondary circuit reaches a oressure corresponding to a temperature just above freezing on thesaturated vapor pressure-temperature curve, said pressure responsive means and the snap action of said valve means being proportioned to close said valve means when the refrigerant in said secondary circuit reaches a pressure corresponding to a temperature below freezing on the saturated vapor pressure temperature curve.

11. Refrigerating apparatus including an insulated household refrigerator cabinet having a freezing compartment and a food compartment, a refrigerating system including a freezing evaporator in heat exchange relation with said freezing compartment and a refrigerated plate evaporator located entirely in said food compartment and another evaporator surrounding the outside of a portion of the food compartment, means for thermally shielding the freezing evaporator from the other evaporators and from the food compartment, and control means for said refrigerating system for maintaining said freezing compartment and said freezing evaporator below freezing temperatures at all times and for cycling said refrigerated plate evaporator upon a defrosting cycle above and below freezing and maintaining said food compartment at temperatures above freezing.

12. A snap action valve including a valve body having a valve seat and a fluid passage associated with the seat, a valve member adapted to engage the valve seat to close the fluid passage, a bellows having its open end sealed to the valve body and its closed end connected to said valve member, and a set of column loaded toggle links having their adjacent ends connected to the closed end of the bellows and having their outer ends connected to the valve body for providing snap action movement, said valve body having a second valve seat and a second fluid passage associated with the second valve seat, a second valve member for closing said second Valve seat, and a connection between said second valve member and the closed end of said bellows.

13. Refrigerating apparatus including an insulated household refrigerator cabinet having a freezing compartment and a food compartment, a refrigerating system including a liquefying means and a freezing evaporating means associated with the freezing compartment and a food compartment evaporating means, said freezing and food compartment evaporating means being connected in parallel fluid circuit arrangement with each other, a check valve at the outlet of said freezing evaporating means, a snap acting pressure operated valve at the outlet of said food F2 compartmentl e'vapcrating'.l means, and' means operated by said pressure' operated valve when in closed posiiionfor' positively opening said check valve'A whenever `said pressure operated valve is closed.

1'4". Refrigerating' apparatus including an insulated household refrigerator cabinet having a freezing compartment and a food compartment, a refrigerating systemy including a freezing evaporator in heat exchange relation with said freezing compartment and a refrigerated plate evaporator located entirely in said' food compartment and another evaporator surrounding the outside of aportion of the food compartment, means for 'thermally shielding the freezing evaporator from the other evaporators and from the food compartment, and control means for` said refrigerating system for maintaining said freezing compartment and said freezing evaporator below freezing temperatures at all times and for cycling said' refrigerated plate evaporator upon a defrosting cycle above and below freezing and maintaining isaid food compartment at temperatures above freezing, said refrigerating system including a primary refrigerant liquefying means for supplying 'liquid refrigerant to said freezing evaporator, said control means including means for-cycling said refrigerant liquefying means.

JAMES W. JACOBS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,036,756 Hull Apr. 7, 1936 2,038,198 Replogl'e Apr. 21, 1936 2,050,959 Ncrmelli Aug. 11, 1936 2,154,299: Bixler Apr. 11, 1939 2,181,276 Koge1 Nov. 28, 1939 2,352,798 Miller July 4, 1944 2,449,688 Brinkoeter Sept. 21, 1948 2,503,922 Schumacher Apr. 11, 1950 2,580,219 Cooper Dec'. 25:, 1951 2,580,220 Cooper Dec. 25, 1951