US2320055A - Refrigerating apparatus - Google Patents

Description

May 25, 1943. C, A, UCKEL 2,320,055

REFRIGERATING APPARATUS Filed Oct. 28. 1940 INVENTOR BY' Carl A. Srckel ATTORNEYS Patented May 25, 1943 UNITED STATES f PATENT l to Pfl-ICE REFRIGERATmG APPARATUS Carl A. Stickeli Dayton, Ohio, assignor to Gen-eral Motors Corporation, Dayton, Ohio, a corporation of Delaware Application October 28, 1940, Serial No. 363,088

s claims. (Cisz-s) This invention relates to refrigerating apparatus and more particularly to means for controlling the circulation of refrigerant through 4evap'orating means'. .Y r

Ordinarily,.expansion valves are controlled by 5 the pressureof the refrigerant'in the evaporator and byV theL temperature adjacent the outlet of the-evaporator. Such valves tend to maintain the evaporator lled with refrigerant ata substantiallyconstant temperature. This is satis- 10 factory as long as the environmenttemperature remains constant and the evaporator is yoperated above freezing temperatures. When the environment temperature rises or falls, the amount of refrigeration should be increased or decreased.

. temperature of the' medium cooled.' l

It is still another object of my invention to provide a means for closing an expansion valve when the temperature of the medium cooled reaches a predetermined low temperature and to open the valve when the evaporator reaches a predetermined high temperature which is suiiiciently-high to provide defrosting of the evaporator. A

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferredform o f the present invention is clearly shown.

In the drawing: 'Ihe fig-ure illustrates a diagrammatic refrigerating system provided with an expansion valve embodying one form of my invention. 4 l

'l vided upon the valve housing to which is'also sealed the rim of a cap member 648 which sur- Briey, I have disclosed a refrigerating system o in which a thermostatic automatic expansion valvehas an additional snap-actingcontrol` addedtheretowhich moves the valve to closed position'when the medium cooled reaches a pre- 50 determined low limit and which allows the valve to open when the evaporator reaches a prederammed high temperature Alimit sufficient to insure defrosting. v 4. Referring now to the drawing, there is shown?, 54

of the evaporating means 24.

a motorcompressor unit including a. compressor 2|! driven by an electric motor 2 2 for withdrawing evaporated refrigerant from an evaporating neans 24J through a suction conduit 26. From the compressor 20 the compressed refrigerant is" forwarded to a condenser 28 where it is liqueeii and collected in a receiver 30. From the receiver 30, the liquid refrigerant is forwarded through a liquid supply conduit 32 to yan expansion valve generally designated by the reference character L y I 34 which controls the supply of liquid refrigerant into the evaporating means 24. The evaporating means 24 and the expansion valve. 34 are located within an insulated compartment designated by thexdot and dash line36. 'I'his compartment contains a medium such as air which is to be cooled by the evaporating means 24. @l The evaporating means 24 is merely indicated diagrammatically and may represent any style of evaporating means. Normally, such evaporating means will Abe of the cross-iinneditype with either forced draft or natural air circulation.

The expansion valve '34 includes an inlet 40 leading to a vertical passage 42, the lower end of which is provided with a yvalve seat bushing 44. The valve seat bushing 44 is provided with a passage leading to a valve seat which may be closed` by the valve needle 46. This valve needle 46 is provided with a tapered collar 48 which is normally held against its seat within the valve guide memberl 50 by a light compressiontype` coil` spring 52 which is retained within the valve guide 50. A compression type coilspring 54 is locatedbeneath the valve'guide 5\and tends to hold the valve needle 46 against its, valve seat to keep the expansion valve 34 closed. 'I'his coil spring'54 is adjusted by a spring retainer 56 whichv is threaded upon an adjusting .screw 54 rotatably mounted in a nipple provided upon the lower end ofthe valve housing 62.

rounds the bellows $4 and provides'a thermostatic Achamber 10 therebetween. This thermostatic'chamber is connected by a tube 12 to a thermostat bulb I4l located adjacent the-outlet thermostat bulb 14 is lled with activated. char- I woal ofsome suitable grade, and the chamber 1I aswell as the-tubing l2 and the bulb 14 are also Preferably, the

charged with a suitable gas, such as carbon dioxide, which will be adsorbed and evolved from the activated charcoal in the bulb 14 according to temperature changes at the outlet of the evaporating means 24.

This control tends to maintain the evaporating means 2,4. substantially filled with liquid refrigerant. Within the bellows 84 is a pressure chamber 16 which is provided with access to the outlet side of the expansion ivalve through the passage 18. In this way, the interior of the bellows 64 is subject to the pressure of the refrigerant within the expansion valve 24. The bellows 64 is connected to the valve guide 50 by three symmetrically positioned operating pins 80 in order to move the valve needle 46 to open position. I'his portion of the valve is conventionalin its general aspects.

At the side of the valve housing 62, I provide a mechanical control which is superimposed upon the valve in order to con-trol the evaporator 24 according .to the temperature of the medium within the compartment 36. In order to do this, I have provided a flexible diaphragm 82 at one side of the expansion valve. This diaphragm 82 has its edge portions clamped between a bead provided upon the valve housing 62 and the face of a supplementary housing 84. This diaphragm t 4 terior of the valve guide 50 so that its end is in a position to engage thelower end of the valve needle 4B in order to forcibly move the valve needle 46 to closed position against the tension of the spring 52 regardless of thev position of the valve guide 50.

The other end of this lever has an arm 88 which surrounds a thimble 90, slidably mounted within a cylindrical passage provided in .the Supplementary housing 84. This lever arm 88 is provided with a projection 92 which engages the lower rim of a collar 94 which is'slidably mounted upon the thimble 90. The upper end of `the thimble 90 is'provided with a flange 98 ywhich serves as a stop to retain the collar 94 on the thimble 90 for the purpose of providing a lost motion or one-way connection between the thimble 90 and the coll-ar 94. The collar 94 is provided with la snap action mechanism including a set of toggle pins |0| which are seated at one end in notches provided i-n the collar 94 and sgeated at their other end in pivoted arms |03 aazmos's mostatic bulb |29 located in the medium to be cooled at some point which is most likely to 'respondrapidly to the temperature of the me- At the end of the supplementary housing 94 .there is provided a second bellows mechanism including a bellows I3I having its open end-sealed to a iiange |33 provided on the housing 84. rounding this bellows I 3| is a cap member |39 having its rim likewise sealed to the flange I 33. This provides a thermostatic chamber |31 be- .tween the bellows |3| and the cap member |39V which is connected by the tubing |39 .to the thermostat bulb |4| which is preferably clamped to that portion of evaporating means 24 atwhich` the frost disappears last vwhen the expansion valve 34 is closed. This bulb |4| preferably is likewise filled with some suitable grade of activated charcoal and the bulb I4I, the tubing |39 and the chamber |31 are charged with a suitable vgas such as carbon` dioxide.

The bellows |3| is acted upon by a thimble |43 held against .the bellows by a.compression type coil spring |45 which has its tension adjusted by an adjusting screw |141, threaded into the plug |49. This plug |49 1s threaded into .the housing 94 and is sealed by a cap screw ISI. The thimble |43 is provided with a iiange |53 at its lower end which bears upon a pair of levers |58 having their opposite ends bearing upon a flange pro- 94 across the dead-center position of l.the snap acting mechanism to the position shown in the figure. I-n this position, the lower flange of the collar 94 is shown resting upon the projection "92 ofthe lever arm 88. IThe lever, constituting the lever arms 86 and 88, has been pivoted in a counter-clockwise direction with the diaphragm 92 as its -pivot point. This causes .the end of the lever arm 88 to bear firmly against the lower end of the valve needle 48 in order to hold it .in closedl which are connected by the transverse bars |05 and a pair'of .tension coil springs |01 extending between the ends of the bars and provided with adjusting nuts |09. Through this adjustment, the snap acting mechanism may be adjusted to increase or decrease its diierential.

The thimble 90 has an inner flange which receives. the lower end of a compressiontype coil spring The upper end of this compression type coil spring is supported by a spring retainer which is provided at the lower end of an adjusting screw ||3. This adjusting screw ||3 is provided within a plug ||5 threaded into the supplement-ary housing 84 and closed by a cap screw I I1. lThe lower end of the thimble 90 is held by the spring II I against the closed end of a flexible metal bellows ||9 having its open end sealed to the flange |2| provided upon thevhousing 84. A cap member |23 surrounds the bellows ||9 and has its rim sealed to the flange |2I. This provides a thermostatic chamber |25 between the bellows ||9 and the cap |23. 'I'his thermostatic however, will be opposed by the compression position. This shuts oi the supply of refrigerantI to' the evaporating means 24, thus allowing vthe temperature of the evaporating means 24 to rise 'Y and to graduallyreduc'e the amount of refrigeraizlon provided. This will arrest the fall inl temperature of .the medium within the compartment 36 lanciwill 'cause this temperature to rise slowly. v

As the temperature of the medium within the compartment 36 rises, .the pressure within the thermostatic chamber |25 will gradually increase in accordance with the temperature of the bulb y' |29. This, however, will not produce any move` crease, thereby increasing the pressure withinthe thermostatic chamber |31. This pressure,

spring |45 and the snap action mechanism which has a certain differential to which it Ihas been adjusted. n

Sur-l The tension of the spring |45 is so adjusted that whenl the temperature of the bulb Ill reaches about 34 or 35 F., the pressure within the chamber 131 wiil be sufficient to force the thimble |43 downwardly to move the levers 155 in a counter-clockwise direction so that their opposite ends will raise the collar 94 and throw predetermined low temperature, and which is opened when the evaporator reaches a defrosting temperature. The temperature at which the valve is closed 1s adjusted by the adjusting screw 92 which may be reached by removing the cap nut H1 while the evaporator defrosting temperature maybe adjusted by adjusting the screw |41 which may be reached by removing the cap screw ISI. Thus, by this mechanical mechanism which I have added to the expansion valve, I have provided intermittent defrosting together with a control of the temperature of the medium. The expansion valve is open as long as is necessary 4to bring the temperature of the medium to the low limit, and is closed as long as is necessary to insure defrosting.

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

What is claimed is as follows:

1. Refrigerating apparatus including liquefying and evaporating means, a medium to be cooled, said evaporating means being located in heat exchange relation with said medium, valve 'means for controlling circulation of refrigerant between the liquefying and the evaporating means, mechanical closing means responsive coming the vnorma1 control of the valve to close the valve, and means responsive to the temperalture of a portion of said evaporating means for releasing said closing means.

3. Refrigerating apparatus including refrigerant liquefying and evaporating means, an expansion valve for controlling the now of refrigerant from the liquefying means to the evaporating means, a medium to be cooled, said evaporating means being located in heat exchange relationship with said medium, said expansion valve including normal control means responsive to the refrigerant in the evaporating means for normally Vcontrolling the operation of the valve, an addi- .tional independent closing means independent of the normal control of the valve responsive to the temperature of said medium for overcoming the normal control of the valve to close the valve, snap acting means for controlling said closing means, and means responsive to the temperature of a portion of said evaporating means for overcoming said snap acting means and releasing said closing means. v

4. Refrigerating apparatus including refrigerant liquefying and evaporatingmeans, an expansion valve for controlling the flow of refrigerant from the liquefying means to the evaporating means, a medium. to be cooled, said evaporating means being located in heat exchange relationship with said medium, said expansion valve including normal control means responsive to the pressure of the refrigerant in the evaporating means andto the temperature of the refrigerant adjacent the outlet of the evaporating means for normally controlling the operation of the valve,v

controlling the other of said functions.

solely to the temperature of the medium for I mechanically closing said valve means, and mechanical means responsive solely to the temperature of a portion ofthe evaporating means for mechanically releasing said mechanical closing means.

2. Refrigerating apparatus including refrigerant liquefying and evaporating means, an expansion valve for controlling the flow of refrigerant from the liquefying means to the evaporating means, a mediuml to be cooled, said evaporating means being locatedin heat exchange relationship with said medium, said expansion valve including normal control means responsive lo the refrigerant in the cvaporating means for normally controlling the operation of the valve, an additional independent closing means independent of the normal control oi the valve responsive to the temperature of said medium for over- 5. Refrigerating apparatus including refrigerant liquefying and evaporating means, an expansion valve for controlling the flow of refrigerant from theliquefying means to the evaporating means, a medium to be cooled, said evaporating means being located in heat exchange relationship with said medium, said 'expansion valve inciuding normal control means responsive to the pressure of the refrigerant in the evaporating means and to the temperature of the refrigerant adjacent the outlet of the evaporating means for normally controlling the operation of the valve, an additional independent means independent ol the normal control of the valve for overcoming said normal control of said valve to provide a closing function and an opening function, snapacting means for controlling said independent means, said independent means including means solely responsive to the temperature of said medium for controlling one of said functions, and means solely responsive to evaporator temperature o for controlling the other of said functions.

CARL A. STICKEL.

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