Патент USA US2133967код для вставки
foci. 25, 193s.. 2,133,967 L. B. M. BUCHANAN CONTROL FOR REFRIGERATING APPARATUS Filed Augflß. 1937 L' as F70» E. WITNESSES lNvl-:NToR LssL/z B. M DucHmvnN. 6_ H BY ATTORN mensa oci, 2s, 193s - y l - i, V2,133,967- UNITED STATES ‘PATENT OFFICE CONTROL Fon REFRI'GERATING >APPA nATUs Leslie B. M. Buchanan, Springfield, Mass., al signor to Westinghouse Electric & Manufac turing Company, East Pittsburgh, Pa., a cor poration oi' Pennsylvania ’ Application August 18, 1937, Serial No. 159,858 '10 Claims. My invention relates to refrigerating apparatus and has -for an object to provide an improved control therefor, ~ ` A further object of my invention is to control 5 the operation of a refrigerating machine in response to the temperatures’or different zones being cooled, . . . A further object of the invention is to limit 10 the maximum temperature of a cooling element (Cl. 62f-4') sponse to a predetermined low temperature of aIlOther zone. Reference will now be had to the drawing wherein I have disclosed a cabinet structure I0 ÍOI’med Of insulating Wells and Cleñning e Cham~ 5 ber II for articles to be refrigerated. An evapo rator I2 of any suitable type is disposed in heat transfer relation with the air in the chamber II and may include means fOI‘ SUDDOrtinE trays I3 of a _refrigeraung machine and the 'minimum ' in which media to be concealed Or maintained 10 temperature of the media coded thcrebic A still further object of the invention is to provide an improved thermostatic control for a _ refrigerator that responds to temperature con“’ ditions inaplurality of remotely disposed regions. These `¿md other Objects are effected by my ' 2 at sub-freezing temperatures may be disposed. Circulation of refrigerant through the evapo ratOr l2 iS effected by a refrigerant condensing unit generally Shown at M and Preferably in“ olndïng a Compressor '5 driven by. on oloomo 15 motor i6, and a condenser I‘I, the latter being invention as will be apparent from the following cooled 1n any Won known manner suon as’ for description and claims taken in connection with example’ by moans »of o fan -w- Refrigerant the accompanying drawing, forming a part of vaporized in the evaporator I2 at relatively low this appiicaticn’ in which: pressure and temperature by heat abstracted 20 Fig i is a diagrammatic viow of a refrigerator irom the air 1n thechainber II and the media mechanism controlled in accordance with my in- ~ m tno trays ‘3 lo Withdrawn from the evaporator vention; and I2 through a suction conduit I9 by the com Fig_ 2 is a sectional View taken along the iine pressor I5. The withdrawn vapor is compressed '25 H_H of a detail shown in Fig i. to a relatively high pressure by the compressor 25 I have Chosen to show my invention oopiiod I5 and is delivered through a conduit 2| to the to a conventional single evaporator refrigerator of the domestic type but it is to be understood 30 that other forms of refrigoroting apparatus may be controlled equally well including two temperature machines wherein a plurality of evaporate“ oondonser '_7 Wnerein'it is Cooled and o.ondonsrd' Liqmd refrigerant passes from the cçndenser n to the evaporator. I2 through aconduit 22 having a suitable expanslon device’ Such as' for example’ 30 a conventional capillary tube 23 connected there are employed and Operatm at different tempera_ ln. The pressure of the refrigerant is reduced as tures it passes through the tube 23 so that vaporiza The present ,inveâtion deñnes an im_ , 35 provement over the control shown and claimed in my oopending application» Serial No- 159:6571 ñled 0f the August present 18, applicatiOn. and assigned In this t0 theCODending assignee application, I have disclosed a. control of the gen40 eral type vshown in the present application applied to various forms of refrigerators including , a form wherein two different temperatures are maintaincd in diñcrcni; cbambers~ The control disoicsod in the present ar,oiioiaf tion at relatively low temperature may be ef~ ¿eoted in the evaporator ‘L The system de_ 35 scribed heretofore operates on the well known be compressolmcondenser-expander understood that other forms cycle of refrigerating but systems may be employed and controlled in ac cordance with the invention. , 40 In practicing my invention, I provide a con' tr01 mechanism generally ShOWl'l at 25 fOr ini tiating and terminating operation of the con densing unit I4 in accordance with temperature tion operates in a similar manner to the control âfälditmns “il digêäemi zàmes of the cäìmäîrl‘ H’ 45 c is an improvement thereover lin that Ithe mini- municating with a plurality of reservoirs zo and of the aforementioned copending application but zo îlarxîâëa; âllnbe zìnccoänììäëà ïílrêîgtso aîldecâïî mum temperature maintained m the higher tem" 50 peraturo zone may be in err-cess of the maximum temperature of the low temperature zone. In both the present and the copending applications, operation of the compressor is initiated lin response to a predetermined high temperature of 55 one zone being cooled and is terminated in re- 29 for containing a volatile ñuid. The reservoirs 28 and 29 may be of any suitable construction 50 but’ as shown, are defined by bulbs communi. gating with the tube 21, The charge of fluid in the system deñned by the bellows 26, the tube 21, and the reservoirs 29 and 29 is such that liquid is present in one of u ' 2,133,967 E the reservoirs 23 or 29 while the remaining res ervoir, the tube 2ï and the bellows 26 contain gas. The pressure in a thermal responsive system charged in this manner will always correspond the spring 3i and lever 39 permits' overtravel of the lever 33' with respect to the lever 39 during a movement of these members and subsequent to the engagement of the lever 39. with one of its stops ¿52 and 33. _A switch mechanism generally indicated at 44 is actuated by the lever 39 and includes a station ary contact shown diagrammatically at Q5 and a of lowest temperature and, therefore, vthe pres movable contact d3, the latter being carried bya sure of vaporization is determined by thertem perature of said low temperature region. It will ` movable support 37 pivoted at ¿i8 to the. frame. 10 An over-center spring ¿i3 connects the lever '39 be apparent, therefore, that normally the reser voir 28’ being in heat »transfer relation, with the to the support di and eii‘ects a snap-action of the e'vaporator i2 or ina zone of low temperature is latter in a switch’closing and opening direction the lowest temperature portion! of the thermal as the center ofthe spring passes the center of the pivot- 33. Downward movement ofthe con responsive system and contains the liquid. Ac cordingly, expansion of the bellows is responsive tact support di is limited by a stop> 5i. The to the temperature of the reservoir 23 and the switch mechanism 34 which I have shown defines evaporator 62. Should the temperature of the one'form that may be employed', but it will be reservoir 28 be heated to a value in excessoi the understood 'that `any suitable form oi switch 20 mechanism may be used. _ temperature of the reservoir 29 which is normal The compressor motor i6 is energized from a ly higher in temperature than the reservoir 28, suitable power source represented by line conduc the iiuid vaporized in the reservoir 23 would con tors Lr-Lz under control of the switch 35i. Clos dense in the reservoir 29 and, therefore, move ment of the bellows 23 would be in accordance ing and opening of the switch initiates and termi with the temperature of the reservoir 29. As the nates operation of the motor i5 and the com 25 ' ’ rese-“voir 29 responds to the temperature of the pressor i3. ‘ Operation v air in the chamber li, movement of the bellows would bein accordance with the temperature of .As shown in the drawing, the switch ¿i4 is open the air in the chamber ii or higher temperature as the temperature oi the evaporator i2 is below the value at which operation of the compressor 3.0' zone. to the lowest temperature to which anypart of the system is subjected. The reason for this op eration is because the fluid collects in the region In order that the- control of the movement of . is started., Circulation of >condensed refrigerant the bellows may be transferred from the low in heat transfer relation with the thermal ele temperature reservoir 28 to thereservoir 29, suf- , ment or reservoir 28 is not effected at this time ñcient heat is imparted to the reservoir 28 to ele so that this reservoir is colder than the reservoir vate its temperature above that of the reservoir 23 and, therefore, controls expansion of the bel 23. This may be accomplished in’ any suitable manner but, preferably, I employ the heat of the condensed liquid for this purpose. Accordingly, lows 23. The pressure in the bellows 26 is rela tively low so that thelever 33 engages the stop 38. a portion'of the conduit 22 is disposed in heat d0 transfer relation with the evaporator I2 and the reservoir 23, as shown at 3i. During operation of the compressor I5, the circulated refrigerant heats the reservoir 28 so that control is efîected by the reservoir 29 and during inactive»periods of the compressor when circulation of refriger ant and heating of the reservoir 28 is substan tially terminated, the reservoir 23becomes the controlling element. Further reference to the transfer of control of the expansion oi the bel `so lows 23 will be madehereinafter. » The construction oi the thermostat 25 will now be described in detail. A frame member 32 pro vides a support for the various elements of the thermostat mechanism 25 and has the bellows 55 23 secured thereto in any suitable manner. ‘Movement of the bellows 26 is imparted to a lever 33 that swings about a fixed pivot 34. A‘spring 35 biases the bellows 26 in opposition to the pres sure therein and bears against an adjusting screw, In the description which follows, itv will _be assumed that the compressor is started -_in re spense to a predetermined maximum evaporator 40 temperature of 30° F. and stopped when the tem perature of the air in the space i! has been de pressed to 42° F.- The maximum temperature of the air in the space il ‘at the time of starting the compressor and the minimum temperature of the. 45 evaporator l2 at 4the time of stopping the com pressor will vary, depending upon their respective heat loads. In the description which follows, it will be assumed that the. temperature of the air in the space ii increases to 45° F. during the in 50 active periods oi’ the compressor and that the minimum temperature of the evaporator l2 is 24° F. The stop 33 is adjusted to limit downward movement of the lever 33 and contraction of the 55 bellows when the pressure in the bellows corre sponds to a temperature somewhat lower than 30° F., say 29°v F. The other stop 37 limits upward movement of the lever 33 and expansion of the bellows 23 when the pressure corresponds to .a >60 temperature somewhat in excess oi 42° F., such as 43° F. The amount of movement oi the lever 39 permitted by the stops d2 and 43 is just suf iicient to permit operation of the switch 44 and is of less angular extent than the amount of 65 movement 'of the lever 33. 60 shown at 33. Upward and downward movement of the lever 33 is limited by respective stops 3l ' and 38 which are adjustable as shown. A second lever 39 may >be carried by the pivot 345 and is actuated by the lever 33 through a lost 65 motion connection preferably including a spring di secured to the lever 33 and engaging the lever 39 As operation of the compressor has just been 1 as best shown in Fig. 2. The spring is moved by terminated by the opening of the switch as, the the bellows 23 and the Alever 33 and eiîects move ment of the lever 39 through frictional engage 70 ment therewith. Upwardand downward move ment of the lever 39 is limited by stops 42 and 43, respectively, which may be made adjustable as shown. The angular movement of the lever 33 is greater than the angular movement of the lever -75 39 so that the lost motion connection deñned by temperature'of the air in the chamber ii is 42° F. and the temperature of the evaporator is 24° F. 70 Heating of the reservoir 28 by the warm con densed refrigerant is terminated so that the res ervoir 28 becomes colder than the reservoir 29 and, therefore, becomes the controlling factor for determining pressure in thebellows 26. As the nsv alsace? 3 temperature of the evaporator l2` and of the air ‘ that its maximum temperature is about 32' F. ` in the space Il increase due to the heat load whereby defrosting during each cycle is effected. thereon, the pressure within the bellows progres sively increases. Expansion of the bellows is pre vented by the bias of the spring 3l until the pres gure therein obtains a value corresponding to As the minimum air temperature is maintained . at a predetermined value, variations-of the mean temperature thereof are relatively small during relatively wide variations in the ambient or room temperature. The maximum cabinet air temper As the temperature of the evaporator increases ature will vary with variations in ambient tem above 29° F., the'pressure within the bellows 28 10 is suiiicient to` start lupward movement of the perature but the variations in the mean tempera ture are substantially reduced over a conventional -lever 33. Upward movement of the lever 39 is control in which the circulation of refrigerant is also enected, belng'frictionally engaged with the under control of the temperature of the evapora spring Il. When the temperature of the evap tor. In the latter case, the mean temperature is orator is increased toa value of 30° F., the lever subject to wide variation whenthe ambient tem 15 39 will have been moved suiiiciently to eiïect en perature varies as the cabinet air exerts substan gagement of the contacts 43 and 48. The motor tially no control over the refrigerating machine. I9 is therefore energized and circulation of re In the present system, the temperature diiîer -frigerant by the compressor I5 is started. Heat ential of the evaporator will vary with different ing of the reservoir 23 is initiated so that vcon 20 trol of the pressure in the bellows is transferred ambient temperatures although the maximum evaporator temperature is maintained substan t-o the reservoir 29. As the reservoir 29 is sub tially constant. When the -ambient temperature jected to a relatively high temperature of air in is high, the compressor is operated for longer the space Il, the pressure in the bellows rapidly periods in order to depress the cabinet air tern increases. At this time, the temperature of the perature to 42° F. and, therefore, the minimum vals air in the space Il is relatively high, for exam evaporator temperature may be depressed to vai ple, 45° F. . The rapid increase in pressure in the bellows 26 eñects upward movement of the lever 33 until it engages the stop 3l. Upward movement of the lever 39 is prevented, however, by the stop 42 and, therefore, overtravel of the lever 33 with respect to. the lever 39 is permitted by the lost motion connection defined by the spring 4l of the lever 39. Operation of the compressor `l5 effects a reduction in temperature of-the evap orator i2 and the air within the space Il. The pressure within the bellows 2S is progressively decreased but contraction of the bellows is not effected at temperatures above 43° F. as the bias 10 15 20 25 ues below 24° F. The minimum evaporator tem perature therefore is reduced as the temperature of theA ambient or room atmosphere increases. The maximum evaporator temperature is main tained substantially constant for varying ambient 30 temperature but the temperature differential of the evaporator varies inversely with variations in ambient temperature. In control systems wherein the temperature of the cabinet air controls the refrigerating machine, a substantially constant mean air temperature may be obtained but the temperature of the evap orator will vary so that it may operate above and below a freezing' temperature at different times of the spring 35 is insuiiicient to overcome the depending upon the temperature of the ambient pressure in the bellows. When the temperature atmosphere. of the air has been depressedv to 43°, the bias It will be apparent that my improved control of the spring 35 is sufficient to overcome the pres provides for the selection of various temperatures sure in the bellows 26 and initiates downward of .the different zones being cooled and that the 45 movement of the lever 33 so that it is moved minimum temperatures of the higher temperature out of engagement with the stop 3l. zone may be higher than the vmaximum tempera As the spring 4| engages the lever 39, the lat ture of the lower 'tempera-ture zone. By adjusting ter moves downwardly with the lever 33 and out the stops 31 and 38, the temperatures at which the of engagement with the stop I2. When the tem switch M is opened or closed may be varied, and ' 50 perature of the air within the space II has been , the mean temperatures of the evaporator and of depressed to 42° F., the lever 39 will have been the cabinet air may, therefore, be varied relative moved suii‘lciently to effect opening of the switch to each other. 44. Accordingly, operation of the compressor and While I have shown my invention in but one heating of the reservoir 23 are terminated and form, it will be obvious to those skilled in the 55 the reservoir 23 again becomes lthe controlling that it is not so limited, but is susceptible 55 factor for determining the pressure within the art of various changes and modifications without bellows 28. departing from the spirit thereof and I desire, As the temperature of the reservoir 23 is rela therefore, that only such limitations shall be tively low or at a value of 24° F. at this time, the 60 pressure in the bellows is rapidly reduced Aand placed thereupon as are imposed by the prior art or as are speciiically set forth in the append eo the bellows, therefore, contracts until the lever ed claims. 33 engages the stop 39 which as mentioned here What I claim is: .` inbefore occurs when the pressure within the bel 1. In refrigerating> apparatus, the combina lows 2B corresponds to temperatures of 29° F. and ’ tion of means defining relatively low and high 65 below. The complete cycle of operation has now y temperature zones to- be refrigerated, evaporator been described._ ~ , v means for abstracting heat from both zones, From the foregoing description, it will be ap parent that I have provided an improved control , means for circulating refrigerant through the evaporator means, a switch _for initiating and for a refrigerator wherein the minimum tempera 70 ture of the air in the refrigerated zone and the terminating’operation of the circulating means, maximum temperature of the evaporator are a thermostatic device for actuating said switch maintained at predetermined values by a single and including first and second elements respon control mechanism. Accordingly, the evaporator sive, respectively, to the temperatures of the low may be operated at sub-freezing temperatures for and higher temperature zones, said element re 75 preserving frozen‘articles or may be operated so sponsive to the temperature of the low temper ature zone being eifective to clo‘se the switch 2,138,967 è during inactive periods of the circulating means, means effective during active periods of the cir culating means for transferring control of the switch to the element responsive to the temper ature of the higher temperature zone whereby said element is rendered eiîective to open the switch and means for transmitting movement of the thermostatic device to the switch and pro viding for overtravel of the device with respect to the switch so that movement is imparted to the switch during the first portion of a movement a thermostatic device including a bellows and ñrst and second thermal responsive elements communicating with the bellows and containing a lvolatile fluid, said first and second elements being disposed in heat transfer relation with the respective low and high temperature zones, said thermal responsive element associated with the low temperature zone determining the pressure in the bellows during inactive periods of the cir culating means, means r‘or increasing the tem perature of the element associated with the low of the thermostatic device and relative move ' temperature zone to a value in excessl of the ment between the thermostatic device and the temperature of the other thermal responsive element during active periods of the circulating switch is permitted during the remaining por tion of the movement of the thermostatic device. means whereby said other‘ element determines the pressure of the fluid in the bellows, adjust 2. In refrigerating apparatus, the combina tion oi means defining relatively low and high able means for limiting the range of movement temperature zones to be refrigerated, evaporator of the bellows, a switch for initiating-and termi means for abstracting heat from both zones, hating operation of the circulating means, a movable member for actuating the switch, 20 means for circulating refrigerant through the .evaporator means, a» switch for initiating and means for determining the range of movement terminating operation of the circulating means, of the movable member and means for transmit ting movement of the bellows to the movable a bellows for actuating the switch, first and sec ond elements communicating with the bellows- member and providing for overtravel of the bel lows with respect to the movable member subse 25 and enclosing a volatile iiuid, said iirst and 'sec quent to an operation of the switch. ond elements being disposed in heat transfer re. 5. In reirigerating apparatus, the combina lation with the media in the low and high tem tion of means defining first and second zones to perature zones, respectively, ‘a mechanism for transmitting movement of the bellows to said be refrigerated at diüerent temperatures, evap 30 switch and eñective to operate the switch during> orator means for abstracting heat from both the iirst portion of a movement of the bellows zones, means for circulating refrigerant through the evaporator means, control means for initiat and to permit overtravel of the bellows with re spect to the switch during the remaining portion of the movement of the bellows, and means ef 35 fective‘during operating periods oi the circulat „ 20 25 30 ing and terminating operation of the circulation i means, thermal-responsive means for actuating the controlmeans and responsive to a Apredeter- I ing means for raising the' temperature oí" the- mined temperature of the low temperature Zone element associated with low temperature zone for initiating operationv of the circulating means to a value in excess ci the temperature oi the and responsiveto a predetermined temperature element associated with the higher temperature of the higher temperature zone for terminating operation of -the same,l said zones being main- , zone. y 3. In a refrigerating apparatus, the combina tion of means deñning relatively low and high temperature zones to be refrigerated, evaporator means for abstracting heat from both zones, 45 means for circulating refrigerant through the evaporator means, a switch for initiating and terminating operation of the circulating means, a >thermostatic device including a bellows and tained between diiierent high and low tempera tures and the low temperature of _the high tem perature zone being of higher value than the high temperature of the low temperature zone. d. in refrigerating apparatus, the combination 4.5 of means defining ñrst and second zones tovbe refrigerated at different temperatures, evaporator means for abstracting heat- from both zones, iirst and secondthermal responsive elements means for circulating refrigerant through the evaporator means,`a switch for energizing and 50 50 communicating with the bellows and containing ’ deenergizing the refrigerant circulating means, a an expansible ñuid, said iirst-ancl second ele ments being disposed in heat transfer relation movable member actuated in response to the tem with'the respective low and high temperature perature of the low temperature zone during zones, a switch for initiating and terminating periods when the circulating means is deenergized and actuated in response to the temperature of. 55 55 operation ci the refrigerant circulating means, the high temperature zone during periods when adjustable means for determining the range oi the circulating means is energized, means for movement of the bellows, means for transmit limiting the movement of the movable member, ` ting movement of the bellows to the switch and a mechanism for imparting movement of the providing for overtravel oi the bellows subse movable member to the switch and including a GG '60 quent to an operation of the switch, said ther mal responsive element associated with the low connection permitting overtravel of the movable member subsequent to an operation ofthe switch, temperature zone being effective during inac and means for adjusting the amount of overtravel tive periods of the circulating means for deter mining the movement of the bellows, and means permitted by said connection. 7. ln refrigerating apparatus, the combination for rendering the thermal responsive element~ 65 _ associated with the high vtemperature :tone eüec of means defining a chamber to be refrigerated, an evaporator for abstracting heat from said chamber, means for circulating refrigerant through the evaporator, a switch for energizing and deenergizing the circulating means, thermal Ily operated means for actuating said switch and responsive to the temperature of the evaporator for Yclosing the switch and to the temperature of the media in said chamber for opening the same, terminating operation of the circulating means, . a lost motion mechanism .for imparting move tive for controlling the movement of the bellows during active periods of the circulating means. 4. In reirigerating apparatus, the combina 70 tion of means dei‘lnlng relatively low and high temperature zones to be refrigerated, evapora tor means for abstracting heat from both zones, means for circulating refrigerant through the evaporator means, a switch for initiating and 'e e 2,188,907 ment of the thermally operated means to the switch and providing for overtravel of the. mech anism subsequent to an operation of the switch and means for adjusting the amount of overtravel oi the mechanism whereby the temperatures at which the switch is opened or closed may be varied. l 8. In refrigerating` apparatus, the combination of means deilnlng a chamberI to be refrigerated, an evaporator _for abstracting heat from said chamber, means for circulating -refrigerant through the evaporator, a switch for energizing and deenergizing the circulating means, an ex pansiblel bellows for having thermal elements communicating therewith and disposed respec tively in heat transfer relation with the evapora toi- andthe media cooled thereby, said elements and bellows enclosing an expansible iluid, a lever for actuating said switch, means deilning a con 20 nection between said bellows and said lever and providing for overtravel of the bellows with re spect to the lever, means for adjusting the amount of said overtravel whereby the temperature at which the switch is opened or closed may be raised. and means for transferring control -from one of said thermal elements to another so that the element associated with the evaporator is effective during inactive periods of the circulat ing means and the element associated with the media being cooled is elective during active periods thereof.. ,9. In refrigerating apparatus, the combination of means defining a chamber to be refrigerated, an evaporator for abstracting -heat from said 5 tively in heat transfer relation with the evapora tor and the media cooled thereby, said elements and bellows enclosing an expansible iluid, means for selectively rendering the thermal elements ef fective to control expansion oi the bellows so that 5 the element associated with the evaporator is ac tive during deenergized periods of the circulat ing means and the element associated with the media cooled by the evaporator is eii’ective dur ing energized periods of the circulating means, 10 means for limiting the amplitudes of the bellows, a lever for actuating the switch, means for limit ing the movement of the lever and defining a . range of movement therefor and a frictional con- . nection between the bellows and said lever where 15 by movement of the bellows is imparted to the lever when the latter is intermediate the limits of its range of movement and movement of the bel lows relative to the lever is permitted when said lever is at one of the limits of its range. tion of means defining a zone to be cooled, an evaporator for abstracting heat from the media in said zone, means for circulating refrigerant through the evaporator, means for controlling the operation of the circulating means and movable to ñrst and second positions wherein the circu lating means is active and inactive, respectively, means for actuating the controlling means and pansible bellows for having thermal elements communicating therewith and disposed respec 2.5 including elements responsive, respectively, to the 30 temperature of the evaporator and the media cooled thereby, means for selecting the element which is to actuate the controlling means and means deñning a lost motion connection between chamber, means for circulating refrigerant fthe actuating means and -the controlling means through the evaporator, a switch for energizing and providing for overtravel ofthe actuating and deenergizing the circulating. means, an ex 20 10. In refrigerating apparatus, the combina means with respect to the controlling means sub sequent tooperating the controlling means. LESLIE B. M. BUCHANAN.