US2252567A - Art of refrigeration - Google Patents

Description

E; F. HUBACKER ART OF REFRIGERATION Filed March`l4, 1938 `2 shgets-sneet 1 INVEN'roR vZZ;-

ORNEY Patented Aug. 1.2, 1941 Aar' or nnralesna'rlon aan F.` nnbmker, numana ruk, Mien.. minor corporation of Illinois to Borg-Warner Corporation, Chicago.

c Claims.

This invention relates to the art of refrigeration and more particularly that type of refrigeration which is suited for domestic installation.

Inv household refrigeration one of the greatest problems which has been presented has involved the method or means which is employed for controlling the ow of refrigerant in aliquid state into the evaporator. pedients have been resorted to for metering this flow of liquid refrigerant among which have been restricted openings which will permit yonly measured small quantities ofy refrigerant to ow into Vthe evaporator, expansion valves which cle-- pend for their operation upon temperature and pressure conditions existing in the refrigerating compartment or in a portion of the suction line, or float devices of various types such as, for example, a float used on the high pressure side of the system, or a oat used on the lowpressure side of the system.

With the possible exception ofthe float devices,

l .all of these expedients have been more'or less unsatisfactory in that they permit quantities of liquid refrigerant to pass to the evaporator where 'it will fill the evaporator during the ,off-cycle .g

of the machine, resulting in slugs of liquidrefrigerant being drawn off from the evaporator through the suction line upon the initiation of the on-cycle of the machine, thus impairing the eicien'cy and greatly increasing the loadupon the compressor and motory during starting.

While oat devices of one kind( or another have been successfully used to overcome these difficulties, such devices have been found to be relatively expensive, their manufacture necessitating a series of operations which require the exercise of a considerable amount of precaution in order to assure that they will operate properly, Because of this high cost and the delicacy of their constructionffloat devices have not been favorably regarded although they do cure to some extent the above-described deciencies.

\'A cure forsthis situation lies in providing seme means whereby the flow of liquid refrigerant to the evaporator is denitely stopped during the off-cycle of the machine in ordery to prevent the accumulation of liquid unnecessarily inthe evap-- orator. In the present invention 'this h been accomplished by providing a thermostatc expansion valve for controlling the ow of refrigerant through the liquid line to the evaporator, the operation of the expansion lvalve being con- Application March 14, 1938, Serial No. 195,815 I l the controlbiilb. uponthe suction line usually has the eflectjof'shuttingp the expansion valve for a short interval after the machine has ceased to operate, 'but fails to control the flow of refriger- A great many exv ant to the evaporator or maintain such flow stopped after this interval has elapsed. This is caused by. circulation of `the relatively warm air within the provision chamber of the refrigerator which warms that portion of the suction line to which the control bulb is attached. A portion of the` invention resides in means for maintain- .ing the suction line, or the control bulb attached 'theremin as usual cool condition during the.

off-cycle of an intermittently operating refrigerant condensing unit. v

' This expedient for controlling refrigerant flow was so successful that smaller motors having lower torque characteristics were found to be ade quate'for driving the compressor. The maximum pressure in the evaporator is controlled and limited by thema'ximum pressure generated byt the refrigerant charge in the control bulb so as quantities of lliquid refrigerant with which a conto prevent the thermostatic expansion valve from admitting any more refrigerant to the evaporator than' would raise -the evaporator pressure to the bulb limit. It will be understood, however, that this pressure might slightly exceed themaximum `pressure ofthe bulb by reason of the vaporization of refrigerant in the evaporator during the oft-cycle,- but such excess pressure will be relatively "negligible because o! the rather small tinuouscoil 'evaporator normally operates, and such pressure will be reduced almost instantaneoiisly upon the beginning of the on-cycle.

i The capacity of a given size of .motor could thus be increased, by increasing the compressor distrolled by the temperature of the suction line and placement when'using a thermostatic expansion valve withfits bulb so located, but this does not insure against a reduction in the'eiliciency of the apparatus during all phases of its operation.A This vreduction inl efficiency is particularly noticeable, for Iexample, during long drawnv out running periods as when 'a heavy load is thrown upon themachinery during ice freezing. In such an instance the wattage input to the motor is rather low, but the winding temperatures rise to an excessive figure; consequently, it is necessary to provide a motor of large enough size so that for agiven load winding temperatures do not rise much above two hundred degrees Fahrenheit.

In order to maintain the winding'temperatures lbelow such ayfigure without an increase in ca- 55,pacity ofthe motor, a iackethas been provided cbout the motor through which refrigerant, which termined by thek to the evaporator oi' denser where it is again liqueiled prior to being passed on to the evaporator.

With the foregoing general description in view,

the invention will berecognized as having for its object tlievincrease of thecapacity of a refrigerating system without material alteration thereof and without adding to the cost of the system.

It is an object of Vthe invention to provide in combination with a, condensing unit a jacket about the motor oi the condensing unit, which jacket issupplied with refrigerant which is condensed in a portion of the condenser and is returned to another flowing through the motor Jacket It is a further object of the invention to provide means whereby thevsuction line and the liq- 'uid line are in heat exchange relation so that the eiliciency of the system is improved.

portion of the condenser after j An additional object of the invention is to pro- I vide means in a system employing a thermostatic expansion valve for controlling the evaporator pressure for preventing such pressure from rising imduly above the limiting pressure as decharge in the bulb of the thermostatic expansion valve.

It is a further object of the invention to provide means for preventing the flow oi' refrigerant an intermittently operating during the oil-cycle of the It isa further object of the invention to provide means whereby the control bulb of a thermostatic expansion valve derives its temperature from the suction mittently operating refrigerating system and derives its controlling temperature, during the oil'- cycle of the system, fro the evaporator.

A further object of the invention is to provide means whereby the control ic expansion valve andthe it is secured for controlling the evaporator are not unduly heated or have such heat rapidly conducted awayduring the oilrefrigerating system system suction line to which cycle of an intermittently operating refrigerating system Further objects will appear hereinafter as the description proceeds and will be pointed out more particularly in connection with the appended claims. V

For a more complete understanding of the invention, attention Fig." l is a'idiagrammatic sectional and elevaline during the on-cycle of an interbulb of a thermostatthe flow oi liquid into is directed to the drawings of which there are two (2l4 sheets, and in which:

y heat interchanger `32, which has a portion 34 designate similar parts throughout the specification.

Referring particularly to Fig. 1, a cabinet indicated generally at III contains a food compartment tank I2, which is entirely surrounded by heat insulating material I4 and which carries in its upper portion an evaporator indicated generally at I6, in which liquid refrigerant is` adapted tobe vaporized. The evaporator IE comprises a sleeve I8, which has its open end closed by a door 2l provided with a handle 22.

Upon the sleeve I8 there are wound a series of turns of tubing 24 within which the refrigerant is vaporized. The refrigerant is supplied to the evaporator from a liquid line 26 through a thermostatic expansion valve 28 and a short length of tubing 30 which connects the expansion valve and the coils of tubing 24. Refrigerant vapor is withdrawn from the evaporator through a suction line leading downwardly along the rear closed end 36 of the evaporator. This downwardly extending length of tubing 34 terminates in a return bend 38 which leads up wardly/into a section 40 of enlarged inside diameter for preventing liquid refrigerant .which might possibly find its way into the suction line from being carried over into th-suction side of the compressor. After its passage through the portion 40 of enlarged diameter, the refrigerant vapor enters a section of tubing 42 which extends to the suction side of the compressor indicated generally at 44. This section of tubing 42 may be arranged parallel to and in thermal conducting relationship with the liquid line 28 throughout a portion of their extent so as to provide a or heat exchange device for increasing the eillciency of the system.

The motor-compressor 44 is illustrated'as becasing to eliminate the necessity for the useof 'a shaft seal; it-will be'understood, however, that' this disclosure is only for the purposes of'il1us-.

tional view of a refrigerator cabinet and refrigerating system whic embodies the invention:

Fig. 2 is a detail elevational view of the rear portionof theY evaporator and thermostatic expansion valve, looking toward the front portion of the cabinet:

Fig. 31s a detail view of a. portion of anAevaporator and suction line illustrating an alternative method of connecting the control bulb oi' a thermostatic expansion valve to the suction line:

Fig.4 is a detail sectional view of the expansion valve shown in Figs. 1 and 2; and,

Fig. 5 is a side elevational view, partially in section, .of a switch and operation regulating mechanism for controlling the supply of electricity to the motor of the rei'rigeratlng system.

,chargedinto the casing 50 from Similar reference characters. are employed to tration and that the motorand compressor could be separate and still emoy all of the advantages inherent in the invention; The compressor is shown to be of the rotary type, but it will be understood that any other desired type of compressor 46 could be employed.

' The motor 48 occupies the upper portion of a sealed casing' 50 while the compressor 46 is located in the lower portion thereof. Suitable electrical connections 52 connect the windings of the motor to an electrical plug 54 and a switch 5 6, the construction of which will be more fully explained hereinafter.

Refrigerant which has been withdrawn from the evaporator through the suction line 42 is compressed in the compressor 46 and is diswhich point it is led away to a condenser 58 by means of a discharge line 60. The condenser 58 is *illustratedas comprising a series of parallel lengths of tubing 62 which are threaded through cross iins G4 and comprises two sections. 'I'he iirst section 66 to which the discharge line 60 is connected serves to condense and liquefy the refrigerant which -is expelled from the casing 5D. I

From Vthe iirst section of the condenser a line 88 extends to a jacket 14 arranged exteriorly of the casing 50 and surrounding the windings 12 of the motor 48. The line 68 delivers liquid refrig'erant into the jacket l0 where such refrigerant absorbs heat which is generated by the motor its proper seating.

in vaporization of a portion or all of the liquid such vaporized refrigerant is withdrawn from an the upper portion of the jacket 'I2 by means of a line 14, whence it is conducted to a second section 18 v.of the condenser 50 and in which second section the refrigerant, which-may have been vaporized in the jacket 10, is yrecondenscd and reliquefled.

up by the thermostatic expansion valve 20.v

The thermostatic expansion vvalve 20, illustrated morecompleteiy in Fig. 4, includes a body portionlhaving a longitudinally extending refvigerant which is supplied to the jacket 10H ||2 and |24, and, consequently, the operation of the needle 80, and to .this purpose t free end |04, in the embodiment disclosed in Figs. 1

and 2, is disposed partially in contact with the passage 80 provided therein and to which passage 80 the flanged end 82 of the refrigerant line 20 is secured by' suitable fittings` indicated generally at 84. 'A strainer 88 may be provided in the passage 80 to intercept any foreign 'matter which may get into the system and might tend to clog the-needle of the 'expansion valve 20 and prevent From the passage l0 a second passage 00 leads to the valve proper which is positioned within a chamber 80 formed in the body 1l of ythe expension valve. The seat 84 of the valve is pressed into a fitting 82 threaded into a wall extending between the passage 88 and the chamber 00. and

this seat is adapted to be engaged by a needle 9B which is iioatingiy carried in a support illustrated generally at 90, the support 0l and the needless being pressed |toward closing Position byan adjustable spring |00. 'I'he adjustment 'of the .spring |00 is accomplished by rotation of a `threaded plug |02 in a tapped opening in a-fltting threaded into the body 'I0 of the valve 2B. This adjustment is performed at the factory and further disturbance of the adjustment pre--v vented by solder |04 which covers the'.head of the plug |02.

The needle-support assembly 00 derives its movement from push 4pins |00 which are fitted against an equalizer disk |00 carried upon the assembly 98. The oppositeends of the push rods |06 extend through the end wall of the body 10 of the valve 28 and into contact with one portion ||0 of a flexible diaphragm indicated-A generally at |2. The periphery of the diaphragm ||2 is tightly clamped between an annular shouldered portion ||4 provided upon'the valve body portion 18, and a ring member ||0 soldered at ||8 to the body memberl A :second ring member |20 is tightly secured to the ilrst ring' member Illiand provides a support between itself and yscan |22 for a. second or power element diaphragm I' illustrated generally at |24. A push rod |20, *shown lri the present case as being hollow, connects the facing portions of the two diaphragms and isrigidly4 secured to each of them.. A spring downwardly extending portion 34 of the suction wall 00 ofthe evaporator sleeve I8, the rear wall I0 serving as a heat conducting fin which is attached in thermal conducting relationship to After terminating its passage through the second section 10 of the condenser l0 the liquefied refrigerant is permitted to pass through the` liquid line 28 under the regulation which is set the coils 24 of the evaporator (see Fig. 2). From thechamber 98 the refrigerant which passes the valve 84, 00 flows into the line 30 which leads to the coils 24 of the evaporator.

With this valve arrangement the body diaphragm ||2 responds indirectly to the pressure which exists within the evaporator and in the suction line'and opensA the valve when that pressure is increased. The power elementdiaphragm |24 presses againstthe push rod |26 so that any increase in the pressure ofthe power element will r open the valve 'when that pressure is greater than the low side or evaporator pressure. The power element which includes the tube `arid cap |22 is charged with refrigerant and therelforethe pressure onthe diaphragm |24 depends upon the temperature of the feeler bulb |34. The valve. therefore, is indirectly controlled in accordance withl the pressure in the evaporator asa result of 30 changes 'in the temperature of the feeler bulb,

since the evaporator pressure depends upon its temperature, and .therefore the valve really ls ,controlled by the differences' in temperature of the refrigerant in the evaporator and the refrigerant in the tube |30 or the super heat of the `refrigerant in the evaporator. Ordinarily, in this type of valve, the expansion valve bulb is located on the suction line or on the front `of the evaporator\a short distance from the 40 last pass ofl the evaporator coil. If it islocated on the suction line the bulb warms. up. rapidly during the olfcycle aridopens the valve, allow.-

. ing the liquid to leak through the expansion valve ,needle slowly. If the bulb is located on the evapwill correspond to the super heat setting of the valve and an appreciable loss of enicienc'y willcresult because the last two or three coils of the evaporator will not be filled with refrigerant.

With an arrangementl such as is shown in the drawings the temperature of the back sleeve is appreciably above that of the tubes or coils of the l evaporator during the on-cycleof the machine. During the off-cycle, however, the difference-in 'temperature is much less and tends to approach the'tube temperature to within two or three degrecs; this keeps the bulb temperature at a point above the temperature of the tubes which is less than the super heat setting of the valve'and conw sequently the valve will not open tolet refrigerant |28, which extends between the capl |22 and frigerant as is to be employed in the system' but lunder 'a pressure of approximately nve poundsuareinch. f

- e free end |04'of the tube I8) forms a bulb 'le leak provided in the suction line has thepurpose of preventing any small quantities of liquid refrigerantwhich may be in-the evaporator at the start i 435 of the on-cycle'from slugging Iback to theA com- A presser.

Operation of the system-is controlled by a switch 50 (see Figs. l and 5). `Switch 56 cornprises a body or casing |36 which may be supported upon the evaporator in any suitable mariner and which contains'therein mechanism for J establishing and interrupting a circuit through the lines l2 through the compressor.- The lines 02 may be connected by a suitable female plug to for controlling the operation of the diaphragms orator sleeve the temperature ofthe evaporator through. The enlarged' section 40, which is a male plug carriedupon one surface of the vconnectionnthrough a 'opposite end of the taches a tube |84 The lower'end 208 4 body ymember |88. One oithe'contacta o! 'the male plug |88 is -connected to a stationary contact point |,48 while the other of theniembers |88 is connected to a bust-:bar 42 which has electrical length vofexible cable |44 to the movable lever element |48 of the switch.

f Lever element |48 is pivoted'at |88 and supports upon a leaf spring |82 a contact element lilvfor cooperation with the stationary contact' projecting portion I 88 of the lever |46 carries a depending coil spring |68 which has its opposite end hooked around a link |68', pivot#l ally carried by the free'upper end |82- oi' an actuating lever 64.

'The actuating lever |84 is.pivoted'at"|861to the casing and is arranged to derive' its movement from a bellows |88, the free end |'|8 ot which hrs a projecting portion |12 providing a seat i'or a washer`|14 bearing againstthe lever |84. The bellows V168 is rigidly secured' held by bolts |88 to the casing has a iltting |82 which atto the cap |18 in open com'- munication with the bellows |88. The free end of the tube |84 terminates in a bulb |86 which is arranged upon the evaporator sleeve I8 and is subjected to the temperatures Awhich prevail at that point. The bulb |86`and tube |84, as well as the bellows |68 and the cap I'l8., are filled with ain expansible uid.

It will be recognized that as the temperature upon bulb v|86 increases, the pressure of the uid at |l6toacap |18 |26. The cap |18 lthereinwill be increased and will Aresult in movement of the free end of the bellows |88 toward the -left as viewed in Fig. 'and in a counter` amt-wv i i v left vin- Fig.- -5. yBuch rotation and engagement" of these two members. will swing the contact button |84 out `of contactwith the button |48 to interrupt their-engagement and maintain the relatively l5 clockwise movement of the lever |64 about the pivot |66 to swing-the upper end of the lever to the left as-viewed in Fig. 5. This swingi ment ofthe lever to the left stretches the 'spring |58 and causes it to snap the switch lever |46 in a clockwise direction and bring the contact points |64 and |40.into electricity conducting relationship; thus Vestablishing-.a circuit to the motor of the compressor unit.

The switch 56 is-also provided with means for overbalancing the force exerted by the bellows |68. To this end, a compression spring |88 is positioned to bear against that side of |64 opposite the bellows |68, the opposite end of the spring |88 being conned by a. cup-shaped *washer L98 threaded upon a shaft |82 which extends through a wall |84 of a the casing and ter? minates in a'icontrol knob |86 exteriorly of the casing` |26. It will be recognized that wtation of theshaft |92 by means of the knob |88 will result in increasing or decreasing the loading of the spring |88.and, accordingly, will either increase or decrease 'the pressure which must be developed within the bellows |68 in order toswing the contact point |64 into engagement with the contact point |40.

A stop 280 'is formed intcgralvirith an inside wall ofthe casing and provides a surface lagainst which a projection 202 of the lever |84 may abut 4to prevent ndue rotation of the lever |84 in a counterclockwise direction. Stops 284 vided upon 'the inside wall of the casing adjacent the link i60 to limit the swinging movement of the link |88 under the impetus of the spring|88.`

of fthe lever |46 has a portion which projects Sinto v1a. slot (not shown) in the wall |94 :and is Vadaptedto be engaged by a projection '281 integral with the shaft. |82 when 'the shaftfis rotated toits limit of movement in `the lever w evaporator. an

a. counterclockwise direction as viewed from the `7 or controlling the circuit to the motor This expedient is employed for the purposes of detrosting` the evaporator.

In Fig. 3 there is shown an alternative method of connecting the control bulb to the suction line. In this embodiment of the invention, the suction line rial 228 which insulating materialserves to protect this section of the suction line from the high temperatures which may prevail in the food compatmentof the refrigerator. The bulb |24 of the thermostatic expansion valve 28 is arranged in contact with the suction line nv within the insulating mnterintzzo. being 1ocated in a chamber 222 provided in the mass of insulating material 228. With .this arrangementl the insulating material serves to maintain the temperature of the suction line at a temperature which correspondsl to the temperature of the refrigerant therein and prevents the control bulb |24 from warming` up during the oiI- cycle of the machine and from opening the valve to permit refrigerant to iiow past the needle 86.

It is contemplated that any desired. means may be employed for preventing the expansion valve bulb from warming up too rapidly dur--` ing the olf-cycle of the machine.

While the invention has been described with some detail, it is to be understood that the description is for the purpose of illustration only and is not denitive of the limits of the inventive idea. The right is reserved to make changes in the details of construction and arrangement o f parts as will fall within the purview of the attached claims.

I claim:

l. A refrigerating system comprising an evap. orator, means for supplying fluid refrigerant to said evaporator and for evacuating iluid ref `gerant from said evaporator, including means ilow of refrigerant to said evaporator. said control means comprising a valve and means lresponsive to the heat existing in the discharge portion of said evaporator and to the heat existing in a n forming part of saidl refrigerant evaporator, a line for carrying liquid refrigerant to said evaporator, a suction line for withdrawing vaporous `refrigerant from 7said expansion valve located in the liquid line for controlling theiow of liquid to the evaporator, and control means for said valve including a bulh disposed in thermal conducting relation with the suction line and with a iin/nf said evaporator. v 3. A refrigerating system comprising an evap rator, a line for supplying liquid refrigerant to said evaporator, a suction line for withdrawing vapovrous refrigerant from said evaporator, an adjustable oriiice in said liquid line, and means controlling the size `of said orifice including thermally actuated means'deriving its temperature partially from the temperature of the sucand portions spacing erant conducting portions, a line for supplying permanently interrupted.

82 passes through insulating mate-y vture in part from the temperature of the suction means for maintaining said portion of the suction line in cooled condition during the offline a'nd in part from the temperature of said evaporator spacing and supporting portions.

, 5. -In a refrigeratlng system, a compressor ar' ranged to be operated intermittently, an evaporator, liquid and suction lines connectingl the compressor and evaporator, means controlled by the temperature and pressure existing in the suction line for regulating the flow of refrigerant through the liquid line, and means for maintaining a low suction line temperature during the o-cycle `of the compressor.

6. In a refrigerating system, a compressor arranged to be operated intermittently,l an evaporator, liquid and suction lines connecting the compressor and the evaporator, means controlled by the temperature and pressure existing in a portion of the suction line for regulating the iiow of refrigerant through the liquid line, and

cycle of the compressor.

7. In a refrigerating system, a motor-compressor arranged for intermittent operation, an evaporator, a condenser -for condensing refrigerant discharged from the compressor; a liquid line connecting the condenser and evaporator, a suction 'line connecting the evaporator and compressor, means controlled by the temperature and hence in accordance with the pressure of the suction line for regulating the flow of refrigerant through the condenser and liquid line, and means for maintaining the suction line in cooled condition during the'off-cycle of the compressor, said condenser including an intermediate portion for supplying cooled refrigerant to the motor of the motor-compressor.

8. In a refrigerat'ing system, flow control means for the refrigerant having an actuating member positioned :upon the suction line of the system, and means for maintaining said ilow control means in cooled condition during all stages of operation Vof the system.

. EARL F. HUBACKER.

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