US1782688A - Refrigerating system - Google Patents

Description

3 Sheets-Sheet, l

Nov. 25, 193. .1. F'. HOFFMAN REFRIGERATING' SYSTEM Filed Aug. 1, 1927 Nov. 25, 1930. J. F. HOFFMAN REFRIGERATING SYSTEM Filed Aug. 1, 1927 3 Sheets-Sheet, 2

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mvENToR Jah/7 ff/Wa/z ATTORNEY um uw Nov. 25, 1930. J. F. HOFFMAN REFRIGERATING SYSTEM 3 Sheets-Sheet, 3

Filed Aug. 1, 1927 INVENTOR (0/7/7 Ebb/f /f ATTORNEY Vis vlfalentccl Nov,

lunjlffrspffsrm-rs@ -PA-ranr orrlca .murio-1mm, or ouAmNnBnAsxArA'ssIeNon '.ro BAKER Ion IAcHnm sonic., A

' or ontAnA, mAsxA; -A CORPORATION or NEBRASKA lamrBjIcamA'-rINc, sYs'r-mr Application illed August 1,1927, Serial No. 209,631, Y

My invention relates to refrigeratin vs s- .temsa-nd more particularly'to one o t at class employing ammonia as a refrigeration medium and 'including a plurality of units v5 for refrigeration in lseparate' compartments wherein different `temf'reratures f are to b e ^maintained ,substantiallyiconstant.,

-Itlis aprincipal ob'ect of my inventionto individually control t e units in the separate l compartments whereby' refrigerant maybe supplied to each independently .of the other andto automatically.connectand disconnect the units with`I the source of supply in ac `corda'nce with the temperature conditions such` compartments.

It is a further object-of my 'invention to eliminate reverse cycling of the refrligerant from a'unit in a compartment of hig entemjperature to those units in compartments of 1uwer'temperature through the lowpressure Itis a f urther' object-of my invention vto "provide for major ow 'of refrigerant to "a unit A under manual control and limit autofmatic control to a minor iow -s'uicient in volply an indirect refrigeratmg coil located 1n ume to include load fluctuations.

I Itis a further 'obj' `t of my invention' eectvdefrosting of--the refrigerating units by 0 fdium'. v In accomplishing these and other objects oi the invention- I have provided va system and;

apparatus, v the preferred'form of whichis illustrated vin the' accompanying drawings, gffwherei'nn Fig'flfis a diagrammatic view of a reinigert' vj ating systemembodying my invention, illustrating the system as'including three sep-` darete cooling compartments with. their refrigera'ting units, in combination with a 'source of'refrigerantsupply and controlling 'v means.; Il dincluding-'al unit' for indirect 're'- frigeration- '4 i l thermostatically controlled discharge valve forming part of each of the rerigerating .statically controlled and back pressure supreverse cycling of the refrigerating me? number.; For furtherillustration'it willbe Y descri tion'of'ita 'lies uall toeach-'of Fig.2 is"an enlarged ,vertical section'fof a., gal-'s PB v lthe parts as they appear when the thermostat is set by pie'ssure in the suction line t0,\pre vent regulation by varying. temperature. Fig. .3 is a vertical sectionv of the thermo- 515 ply valves' also included in each of the units. Fig.,i L is adiagrammatic View of the discharge valves and controls for the'coils in the high/andnext lower temperature compartments of a' series, illustrating pressure control e0 of thethermostat in a lower temperature compartment while the hightemperature coil is charging.

Referring more in detail to `the drawings: l

1 designates a type ocompressor common- `ly employed in refrigerating systems, shown as operated from ran electrical motor con- I trolled from the described.

Leading from the' compressor 1 is a primary condenser 2 and a receiver 3, both of ordinary construction. `Leadingfrom the receiver 3 is a supply lineft for conducting liquid refrig'` erant to thevarious compartmentsserved by' the system' and w'hichfmayf be tapped to sup- 'I5 thetank 5, and which will be more specificalvreferrelvto following the description of e direct refrigeration.

nin'cold Stora e fwarehousesor'the like and here shown, or illustration, to be Ythree'fin assumed that Athe temperatureof the com.- partment 6 is to be maintained1 at about-38 the-compartment Tat about"20 F.,. and..

' the compertmentB ataboutj" F. f

Asthe mechanical construction, of the re; if

-frigerating unit in e'ach ofthe compartments ignated generally byl and hereinafter more 1,00

system, as will presently be no fis mPtMhemfbr noted, identical withA a t .ihosell thefother compartments, but oewll specifically described. Leavingthe cLoil 1() at,4 t

e top is an outlet branch line 12passing through a thermostatic'condenser jacket 13,

containing gasreferably and hereinafter referred to as a monia gas, 14, whereby the primary control valve mechanism'is influenced for'the purposes presently mentioned.

Leaving the jacket 13 the line 12 passes'into the casing 15 of the remote'control back pres-- sure valve mechanism, indicated generally by the numeral 15, and leaves said valve mecha- Y a suiiicient period to reduce the temperature t of a compartment to the desired degree in-4 sov nism to enter the return or low pressure line 16 whereby the refrigerating agentl is returned to the compressor through a suction line 17. f

When thesystem has been in operation for dicated by the setting of a thermostat within the compartment, it 1s necessary or desirable to interrupt flow of rfrigerating agentto the cooling coil 'in such compartment in order to 4prevent accumulation of an excess of the ,pressor side of said supply control mechanism is a fitting 18 lcomprising a vertical chamber 19 communicating through a nipple 2O with an enlarged diaphragm chamber 21, formed by thel partition 22 and a ca 23 having its rim attached tothe body of t e fitting by suitable bolts 24 and its'inner face chambered to form the upper part vof the diaphragm chamber 21. ,y

Extending across the diaphragm chamber i \with its periphery clamped between the flanges of the body tting and cap is a flexible diaphragm 25, held securely within the valve case by the bolts 24 which secure the ca to the casing 5. Bearin'gagainst the under ace of`thed1al hragm 25 is a reinforcing plate 26 carried ya valve stem 27 which extends through thebore 28 in the nipple 21 and cari ries a valve head 29 tapered to lit within the `valve seat 30 in the lower end of the ni ple 21a The vertical4 chamber 19 is close at its lower end by a screw cap 31 and seated on said cap isa cylinder 32 containing a pistn 33 urged a ainst the valve head 29'by a spring 34, whic seatsin the' bottom of theecylinder and tends to assist lin closin the valvel 29 against its seat to exclude refrigerating medium from the diaphragm'chamber21.

` Opposin the spring 34 at the opposite side of the diap Jragm is aspring' 35,'housed within a dome 36 constituting 'part of the cap '23' and seating at its lower` endin'a cup 37 in fa head 38 attached to the upper surface of the diaphragm.l At its upper end the spring 35 bears against a plate. 39 on an adjusting screw 40,

which is threaded into the topof the cap dome and-whereby the tension of spring 35 is regu- 'l lated to predetermine the back pressure at.

which the valve will close the, line and fshut off the supply. e

Thej principle upon which -refrigerating systems of this character' is dependent is the transfer of heat from the compartment to be cooled to the refrigerating agent during passage of the agent throughV the compartment;

consequently, temperature of the agent is higher upon leaving the compartment than upon entering. The agent enters the cooling coil as a saturated vapor and-transfer ofheat units` from the -compartment to the agent transforms this yvapor into a drier, aseous condition, which is more favorable or operation of the compressor. Should theagent pass through the compartment without doing any useful work, it would leave the compartment in the same conditionat which it entered and in a condition unfavorable for compresser operation. Consequently, it is desircontrolled valve for 'diminishingthe supply of refrigerating agent to,the coil under the condition lastabove mentioned. This valveis preferably of the construction illustrated in Fig. 3 and indicatedgenerally by the numeral 42, which designates the valve casing. The part of the line leaving the back pressure-valve 18 opens from the diaphragm chamber 11 through a port 43 in the partition 22 and-opens into a primary chamber 44 in the valve casing 42, containing a screened scale trap 45 for filtering the re rigeratin agent in its passage to the cooling coil. t e trap 45 rests on the top of a plu 46 in the bottom of the housing andnormal y closing a leanout opening 47.

Leading from the top of'thechamber 44 is a tube 48 connecting the chamber 44 with a ttin 49,' containin a valve (not shown) o erab e by a hand w eel 50 to control ow o refrigerating mediumfrom the chamber through the `fitting. The ttn communicates through a conduit 51,` with t e condenser jacket 13 on theI outlet' line from the 'cooling coiland carries lan indicator 52 for disclosin the volume of content ofthe jacket.

It is t rough this'connection that thel thermostaticfluid is delivered tothe/condenser jacket under'ccntrcl of the valve indicated' in turn; communicates with a chamber 55,

las presently -be described, which I' 5 with the .condenser jacket 13 S V:line l5,1,- nebranch 'of whichleads to the With"` the'. construction'f f s'xhouldV the refrigerating agent/pass freely throughfthe cooling-lcon, temperature in the chamber 5'communicates with 'the lower convolution-of thel coil through a bore 56. .Locatedwithin the Apart of' chamber 54 abovefthe port of `bore 53'is 'a plate 57 hav- 'ing a central aperture'58. Located in chamber 54 below the plate 57 is a head 59,'comrising' a dependmg boss 60an `yupstan'ding l oss-61 and an annular flange. 62.` Seated in the bottom of the chamber 54 aboutan 0 l ing thehea'd 59 against a ball 65 within the central aperture58 in thev late 57 and serv- 'ing as` a valve'to control ow of the refrig- Aerating agent from the chamber 54 Ito the the lower head 67v of a nipple 68 thatslides in the sleeve 69 of a plate 70 inthe chamber- 55, and provided with lateral pprts 71, wherei by liquid from Vthe chamber 54 is delivered from the nipple 68 into the chamber 55.

Located within the bore'of-the nipple 68y and engaging the plate 7 0l is a square piny72 which serves to hold'the valve lball 65 downwardlybut does not interfere with iiow of iiuid through the nipple The plate 70 ,is

vxed onthehlower facefof a' diaphragm 7B,

held between the top of the valve housing 42 and the valve housing cap 74. The cham ber 7 5in cap 74 4isl enlarged at its'lower end soto contain a spring-retaining cup 76.

Seated within they cup 76 is a coiled spring 77, the upper end of whichfits over a cap plug 78 within the u er portiorr'of the cylinder. Extendingft rough the cylinder, is

35 ,a set screw 79 which bears against the cap plug78 and carries la Aluck nut l80\ Wlnerleby n theset screw isheldl yin any lfixed adjustment r to maintain a-constant/'tension"onv the spring,

thescrewbeihg packed and'held tight to pre-5 4o vent displacementy under pressure within the @valveand to avoidleakage fof the thermostatic'medium whereby the diaphragm is operated toeiect the automatic control. 'f1 The chamber 75 of cap 74 Ico unicates roughthe chamber romthe-'valvefiitting 49 through thefsidepf thecylinder and the other .branch of which leads to theV chamber :from the con-7 gense'r ljacket through thej top 'of the cylin er. p"

rigeating agent-may besuppliedto 'the coil -in a', major owof 'substantially 4sulii'cientvolume to serve-the coiland any additional .requirements incidental 'to fluctuations.inI` ation'v "load supplied under automatic re throughfthe back pressurel and t eremostatically' controlled valves.

abovesdescribed,

66 condenser jacket w1 be reduced and the conupstandig `boss 63fis a spring 64, support' chamber55. 1. The ball 65has a seat 66 in,

nding arou'ndfthe supplyi.:'controll valves" 18 'and 42 is a b ,-pass. conduit v8l,

expandedandd the diaphragm returned to yits normalposition to a'gain open the valve and return the system to its normal operationp-z I Passing now to the outlet end of the cooling Vcoil and to the remotecontrol for the discharge valve,'83 designates a receiving chamber in the valve housing into which the resage through the condenser .jacket .upon leav ing the cooling coil. The chamber 83 'is' formed by a partition 84'havin'g an .outlet port 84 leading to l`the outlet chamber 85-10- frigerating agentis delivered after" its pas-f cated in the valve housing below thefpartition f 84 and having open communication with the branch 12 leading to the return line'16. The port '84 iscontrolled by a downwardly closing plate valve 86, having a stem 87 extended through the port 84into a` socket 88 at the -f bottom `of the .casingl where itseats on 'af j spring'89 support/ed by. a follower disk 90 carried by a set' screw 91 pperable 4from ,theI

exterior of the casing ,to adjust tension of" spring-'89 and heldin set `}'1osition by a lock nut 92. The spring is of suicientstren h to normally-'lift the valve86 but will yiel to permit the'valve to close. under the conditions presently described. l f f Extendngffromf he-top of thef' valvev late isa shank 93, carrying a disk 94 which aray against the under face o'fa flexiblediaphra 95 extending horizontally acrossv the va ve"l chamber 83, with its, peri' hery located be- 'casing and 'a flange 97on-the cap member 98;; bolts 99 extending throughv the flangesl and no i through the diaphragm tousecurely .cOIlllet l 'the parts together. l,

Opening' into the vchamber' 101 in the c member 98' above the diaphragm 95 throu a nipple 102isa tube 103, constituting t e either -within or without 'the compartment.

ap y

.s 151# vte'rmirmLof-a thermostatlc coll 104, v which-,IA may be located'fatany convenient Qpostion' under` refrigeration for the 'reason mbit it not dependent uponthe compartment' tem-f peratur'ebut constitutes a primary cqntrolf Subject vmi thermesat 'within the compara flment fand also' toa manual Acontrl for initial the refrigeration unit.' The coil 104 voperates 1 tube intjhat its primary .end`105 is connected setting and subsequent cutting-in-and out 4'of 25 -o the `principle of the. well known Bourdon -f within electricalheatin element, suchlas a; 'I

lamp bulb 106, withsaiv primar end heating elementfso arrangedan mounted l and.Y

\ that Vunder relativelyl high ltemperature the end 105 will tend to straighten and'move the heating element away-from the coil, t hereby extension 120; the tube being sipplied cutting down the heating effect to maintain a predetermined constant temperature-0f contents of the coil, it being'appa'rent that when the coil is inoperative' the heating element will lie closel adjacent the coil so that heat is readily an quickly transferred from the element to the coil and that when the temperatuierises, the lelement is moved away from the coilito reduce the heating eifectr Interposed in the tube 103 is a three-way fitting 107 and leading from the third outlet of the fitting is a tube 108 which opens to the return line 12 of coil 10through a nipple 108 whereby the coil 104 issu pl-ied with Huid from the return line, the tu e 108 being con.

trolled by a valve 109 so that when the coil 104 ,is filled, the connection may be'rbroken.f

This connection is rovided when ammonia is employed as the t ermostatic Huid but'Ivdo not wish to\li`mit myself tothis particular'V thermostatic agent. y .Y

The heating element 106 is ener ized from a suitable source of electrical 'supp /through branch lines 110-111 of a lightin/gY or other main circuit lines 1 12--113- ,Included in thebranch circuitis a thermostatic switch 114 which is located within and subject to changes in temperature ofthe com artment containing the coolingjc'oillO an also included in` the main circuit is-amanual switch 115, which may be located within the compartment un-` `der refrigeration or atany other convenientl place. 1 l l The thermostatic switch which Iprefer to use and which is indicated generally at 114, consistsof a mercury 'tube 117 carried by a clasp 118 which is pivotally mountedona pin 119, above the tube and, has a lower vided with contact i with a thermostat 128, v preferably ofv bellows type nd containing a duid expansible by heat, so that when temperature rises in the g compartment containing the thermostat: and

the coil it. serves, the thermostat expands rocking the lever 125 to lift the link'ql24 and. tilt the mercury tube to 4position Afor iowing the mercury charge away`from the contact,

l stat 114' controlling .such valve' 15. Located points and thereby opemngthe circuit and 'extinguishing the lamp, permittingcontents of `the coil 104 to contract and the 'valve 86 to vqanan under tensinyof its/f'fsprlig'.` Y h en the compartment isfc'opled' toI the leading.

`proper temperature' by refrigerant vrflowing through the coil, the bellows `t erii'iostat.V contracts, shiftingl themercury tube to again vclosethe lamp circuit, expand contents of lthe coil 104 and force the 4valve 86 closed to cut oi flow of refrigerant.

Thereis a separate thermos'taticcontrolv of thecharacter described in each of the separate' "compartments, each control being adjusted to. maintain a given temperature within that particular compartment independently of temperature in the other compartments. u

When the refrigerating. liquid ,is released into the coils, it expands and absorbs heat from the compartments','the flow continuing until the desired temperatures have been reached in' the res ectifve compartments. It

is apparent, there ore, that should refrigerfation of the three compartments to be cooled respectively'ato 38" 20?, and. 59, start'with temperature, flow through the coil' in the 38 compartment must be stopped while flow cony under control ofv ythe compartments jall at lthe same initial maintain the temperatures inl such compartl ments.

` As the refrigerating liquid is carried back from all ofthe c'oils to the compressor through the common return `line, pressure ofy fluid f' passing through the return line from a coilin a compartment of higher temperature might overcome the/valve-controlling flow peratui-e and interfere with proper refrigeration infs'uckh lower temperature com artment.

To. eliminate such `ossibility, provide means, preferably ,of t e construction pres- Ifrom the coil in al compartment of lower temently described, for retaining the discharge V valve of each lower temperature coil closed 7while'any higher temperature coil is passing refrigerant into the return line. 1

'Tapping the branch line 12 leading from ture 'coil is the nipple 130 or ya conduit 131,

having anipple 132 at 'its o pesite end open ing through thecap 133 o a pressure relay c housing 134 arranged ladjacent, the thermo-` .120 the discharge valve -i each lower temperao 1,7sa,ee's i 136 and through. a guide boss 137 at the hase of the housing1 is .a pusher rod138\..adapted for en aging 't e link 124 of the thermostat to rock t e switc 117 against the tension of bellows 128, -b eak thecircuit through the heater 106, and insure closure of the valve 15 .so that shouldrefrigerant be flowing to the return line from the coil oi one of the higher temperature compartments, it will exert pres-y sure on the switch lever 125 of'the lowertemperature unit andi. close thedischarge 'compartmentfof highest temperature.`l I

valveof such unitwhile the higher tem'- perature unit is in operation presentlyT described. The rodis normally restrained and isreturned by a s ring 139 which seats in .the end of the ho sing, surrounds the boss 137 and rod 138and bears against the diaphragm 135. "Y

There 'is a pressure relay like that described in each lower temperature compartment, butnone required nor proyidedin the As flow of refrigerant through the vcoils is interrupted by closure of the discharge valves while vthe temperatures inthe compartments remain within proper ranges, I provide for interruption of operation of the compressor during such periods, preferably employing or that purpose a pressure relay 140 corre-y spending to those previously described and connected with the suction line 17 by a fitting 141 so that pressure in the return lines resulting from low'from any'of the coils will operate the diaphragmv 135 and force the pusher bar 138 into :o'ntact` with acontact member 142.

, The bar 138 and meniber 142 are'connected gized too'peratethe 'compressor and suppl respectively withthe 4line wires 143 and 144" of a power circuit supplying the motor 145,

. so that when there ispressure in' the suction line, the circuit is closed and the motor enerrefri erant to the one ormore coils throng .f whic lflow is required.

v'anay The ppwer circuit be manually controlled y a master switch 146 Vinterposed in the circuit.

In order' to maintain the several compart-v i ments at their respective temperatures, the

heater circuit following a minimumexpanf.

control mechanisms are set to open the valves in`the respective units whenthe temperaturesrise above the-determined 4degrees, the ther# mostat in the 5- compartment to close its sion of vits bellows; that in the 20 compart-` ment only after a ater expansion, and that in the 38 only a r an. expansion great ver than that of the thermostat in the compartment of next lower temperature.' Like- -wise the temperatures and pressures of the refrigerant'leaving the coils are' progressively greater for 38 compartment bein as` high as irty pounds, so that when't e coil i'n any'higher temperature compartment opens to permit recharging, the coils of all lower temperature umts in higher temperature compartments, the refrigerant leaving1 the units will be automatically lclosed to prevent back/cycling and the power circuit will .be closed to start and continue the lcompressor ino eration. l

I preferably also include within the system arl indirect cooling element; i. e., means for 1 coolingvl brine which, in turn,'is,em loyed as a cooling agent for convenient distrlbution to other compartments or any location requiring refrigeiation'or for the'manufacture of ice. This indirect element of the system comprises a coil 147 submerged in the brine tank, 5, the coil bein connected with the supply or highv pressure ine 4 througha branch 148 and with the return or low pressure line through a branch 149.l v

Located inthe supply line 148 .is-afhack pressure.\ and thermostatically controlled valve mechanism 11 and.v by'-pass81 and located in the return line is a discharge valve 15, controlled by a thermostat 114 and pressure relay 134 corresponding' to those pre- 4viously described in connection with the di-4 rectcooling coils 10; the local thermostat controlling the last-named valve mechanismbeing of a type' adapted-for submergence inthe u brine in the tank 5 and connected with the circuit 112-113, asa're the other corresponding thermostatic controlling elements, and which may be set to operateat any desired temperature but need notbe` equi ped with the automaticmeans for contro linuback'f and condenser as well `as unit coils ofnpro er capacity are inc ludedin the s stem, and at an indirect coolin unit is also included in the 'sys that of the coils are with individual thermostats, that eac of the Ythermostats `except the one in the compart= nient 1 of highest temperature is equip with a pressurev relay andf'that the suction ine 'gher ient'capacity to supartn/ients in which I held respectively -at 38, 20.and 5 F.and'that a compressor 110 elplipped is `equi pcd with a pressure relay for controllin t e motor circuit, the operation is .as

fol ows: l

The ma met@ controlling' an r:ma

thermostatcircuitsin the several compart.

ments are closed-but the temperatures in the compartments being'v above teworking degrees, the local circuits are opened by ex'- pansion of thesylphon 'fthe thermostats so that no current flows throu h the heaters 106, ,and the content of the tu s 103 is not expanded to a degree suf-` ficient to expand' the diaphr'aginsv inthe disbellows .elements v ilow of refrigerant through the coils to, the.

V- expande compressor. There being no `pressure in the suctionV line-the points v139 and 142 are held out of contact and the motor is inoperative.

charged with The systemis then initialll cient pressure refrigerant, building up su lin the return'line to operate the pressure relays, close the lower` temperature coils and startr the compressor. f The refrigerating agent furnished to the system is compressed and condensed to liquidand the compressed liquid accumulated in the receiver at a temperature corresponding to the pressure'at which it'was compressed and which we will assume at 90 F. withinv the receiver.

The by-pass and back pressure Valves of the respective units are adjusted Ato permit free flow of the refrigerant to the units until `pressures have been builtup in the units sufiicient to produce the desired temperatures within the compartments, and the automatic ktemperature valves 42m thesupply connections to the several units are adjusted so that relatively high temperatures at the discharge ends ofthe units, such as arenpresent before the refri erant 'is supplied to theunits when will exert pressures on the diaphragms 7 3' tending'to open the valves and permlt free iiow to the units. f

Under these-conditions-when thel system is placed in operation refrigerant 'flows from thecompre'ssor to the severalunits in the system, passing'in major flow `through the bypasses81.l 4 '-5 I As the-unit in the compartment of highest temperature is ndt equippedwith a pressure relay, there is no automatic closing of the discharge valve of this unit, andsuch valve Vremains open .to permit free flow of refrig- I erant through its 'cbil'and back to the compressor.

As refrigerant'continues teli/low through the "coilfin the unit servingl the compartment 'of highest temperature, fthe. temperaA turegin the compartment is lowered untll the proper.. degree is reached, at which timethe 'thermostat 114 win :Shift the memry'tube,

closing vthe local heater circuit, thereby eflfecting'expansion of contents of ythe'eoil 104 A and expansionof the diaphragm in ,thedis- ,l charge valve of such highest `temperature unit and closing the Valve a ainst the tenf sion of its spring, the-local' eating circuit vremainin closed to maintain the heater in closed, pressure in Y t functiona condition, and the'di'scharge valve l closed until rise in temperature Iin the compartment-revrses the' thermostat to again ermitthe valve ,to ouen and refri eant to ow through the coil to the return J ine.

When; the valve 4in the unit serving the compartment 4of hi hest` tem rature is 'e return ine and 4in the pressure relays controlling the thermousata circuits local to such compartment are opened and contents of their coils 104 per- 4 xmitted to contract under influence of the lower temperatures, and the discharge valves in the units of suchlowertemperature compartments automatically opened so that refrigerant then flows through the coils in such compartmentsfto the return line'and back to the compressor. l

As the-temperature at whichthe refrigerant leaves the coils for the lower temper- Vature compartmentsis lower than thatfof the refrigerant passed to the return line from the vhighest temperaturecoil, theV pressure generv ated 4inthe line from the coil in the compartmentof next highest temperature is less than thatvbriginall present in the line, but not sufficient to a ect the pressure relay in such second compartment, although sufficient to operate the pressure relay .in the compartment of lowest temperature. Consequently the thermostat in the second compartment will Abe unaffected by pressure of refrigerant passed to the return line from the unit in that compartment, but the theramostat in the lowest temperature lcompartment will be operated by its pressure relay to close its local-heater circuitl and close its discharge valve thereby preventing back flow of refrigerant into the coil of the lowest temperature compartment from the coil in -the secondi-compartment. v

VRefrigerant then flows through the coil in the second temperature conpartment'until the proper temperature is reachedtherein, when theathermostat in that compartment voperates to close its'local heater circuit, eX- pand contents ofthe coil 104 and close 'the discharge valve, therebystopping the iiow of refrigerant and confining the. refrigerant in the coil. 4. l v g As soon as -thevdisharge valve in the second temperature compartment .has closed, g pressure .is relieved in the return line, the pressure relay in the lowest temperature Vcompartment relieves its thermostat, and the .l thermostat shifts to break its local heater.

circuit and permit the discharge valve of the unit in that compartment to, open, y,thereby permitting ilow'of refrigerant through the coil'of that compartment and back through lsu local heating circuit in t It is `fur er ap parent that while the the 'compartment of lowest temperature losed, pressure in the return line is. again lieved'and toan extent. suiiicient to permit J the pressure relay onthe' suction line to oper-l ate and open the power circuit, thereby cutting off the compressor until temperature has risen inone or more of the' compartments to a degree necessitating recharging of the coil' therein. .a j

If the compartment of lowest temperature is the one irst requiring recharge, the thermostat in thattcompartment breaks the local v heating circuit, permitting contents cfr its. coil 104 to contract and thereby permittingv the discharge valvefof the unit in thatcom? partment to open. v i

When the discharge valve opens refriger .antpassing fromthe coil into the return. line creates apressure inthe return line suffi cient :to shift-the weak pressure relay con# trolling the motor circuit, r-establishingjthe motor circuit and putting the .compressorin operation to deliver refrigerant through the system. The refrigerant-leaving the coil in t e low temperature` compartment. at low temperature' and pressure wil no .disturb the pressure relay in the' compa tment of next highest temperature and the unit in the compartment ofigliest temperature having nofpressune relay, the valves 'inthe higher tem veratnire compartments v*remain closedwhi eth'e coilin th lowest temperature com# partment is beingrecharged,

If, during the recharging of thelowesttemperature compartment, the thermostat of 4the unit in one ot4 the higher temperature com artments should operate to openl the disc arge valve ofthe junit in such higher temperature compartment, then refrigerant leaving. the coil of the higher temperature f unit at 'higher temperature and 4pressure than that leaving lthe lowest temperature coil, andata pressure suicient to operate lthe pressure rela-yfofbthe low temperature compartment, the pressure ,relay of such'lower temperature compartment will actuated'toL shiftthe thermostat in such com artment to close the hat compartment and close the vdschar e valve of such unit, even though the ehagingof the. coilin such unit has not'bee'n completed, thereby preventing lback flowl of refrigerant from'a higher tem-- perature unit into the coil of a lower temperatureunit. v 1 lt is a parent, therefore, that at no time e operation of the system can lrefrigerant pass from any unit ofhigher tems perature back to a unitof lower temperature to. raise the temperature of such lower temperature compartment, and that control ofa allof the units is automatic' and individual so. that each compartment is 'constant-lyI .l lautomatica]ly maintained at its proper 1nd1- vidual tern* cratere.

presser is vany orl all of the units when re iautmaticallyshut down except uri ng'such l lby controlling i'ow through 'the intake and outlet ends.

compartment and.

remove the frost incrustation.

As this automatic die perature coils, back pressure and regulating .valves atth'e high temperature operable-to supply .refrigerant to' uired, it is periods as its operationisnecessary for sup Py`-". When .the system is being placed/in oper. .in ation thet'refrigerant .is supplied to the several coils-1n a major unrestricted flow through the try-passes 81, but after the coilshvebeen initially7 charged .the by-pass may be cut off 75 and..v further automatic charging ele'ctedf. through 'the automatioback pressure. and y regulating valves .at-thesupplyend'bf the units. When acoil is. `illed and pressure built 11p-' so therein to theproper degree, back pressure v in the c oil operates the pack pressure valte and cuts 0E the sup'ply'of refrigerant, there-4 the c'oil at both vAs the refrgerant1n. those compartments held;A at a temperature above the freezing point, passlng vfromlthecoil tothe return line,lis at a`temperatu'rebelow thatl of freezl ing,.any moisture in the compartment served 9o by the coil will settle on and frostthe coil. A When l the unit is, automatically ct. Soif .through the thermostatic control, the liquid in the coil 1n a compartment heldat a temperaturex-above `the -freezing point rises in ed temperature toapproach temperature of the yhen it fpasses abovegthe freezing point, tends to melt the, frost and frosting cannot -ltakefo'e place in a compartment-held belowr the freezf ing point, I provide manually controlled means for effecting defrostingof 'such units; This4 manual control includes-the by-pass-` about the back. vpressure and vregulating valves at the intake end of each coil, together with the valve controlling dischar froml -the unit andjwhich is normally -un er automatic control ofjthe thermostat 114. YV'herrl it is desired-to I open .the bypass aboutit-,hel

intalev end .ofthe coil and open the circuit -to the';electrical heater 10i) so that the Lther.- mostatic switch cannot eiect opening of the 1115 having entered the lc oilat a' temperature of a proximately 90?,

it is apparent that this on the coil willtend to melt the frost and-'125 cleanthe surface. 7 i

Defrosting of any one of theunits does not interferev with the normal operation of the other units as thejopenin of'the circuit locallyat any of the units w1 not interfere 1:3

defrost one ofthelowtem.- y

line, accumulates in i the x:oil. .Being unableto4 expand and per- 1 20 vform its lnormal.reirigerating function and acting on the incrustation @1. In a refrigerating system,

Y, erant through the units,

with. automatic opening and /closing' of the circuit through the thermostats 'at the otherv unitsr It is apparent,` therefore, that I have provided a refrigerating system wherein independent units served by the system may operatelto maintain different temperatures `1n different compartments Without interference one with the other, that such units are automatically controlled A by local Atemperatures `and thatdefrosting of the coils in 'higher temperature compartments is automatic and that lin lower temperature compartments may be 'effected at will and `without interference,

with the operation of anyof the other units.

What I claim and desire to securebyLettersPatent is v:--l Y a plurality of independent cooling units, .for serving. a separate compartment, single supply and return lines, havin branches Ito said units, means controlling o w of refrigin'cluding thermostats respectively operable at different temperatures, and means-responsive to pressure in the return line controlling some of said thermostats.

2. lA refrigeffaung system, `ifa-,lading a plarality of independent evaporator coils, each arge valve atv its Y outlet end responsive to variations in temhavlng an automatic disc perature of 4aV compartment served by the J,ply and return lines, the coils, means localto each coil and responcoil, supply and return lines, each commonto all of-the coils, andmeanslocal to the discharge valve of one unit and responsive to pressure supplied togthe returnlinefrom another unit for controlling said valve.

3. Arefrigeratingsystem,includin a P111- rality of independent evaporator coi asup' each common vto all of sive toy variations in temperature in a .cm-

:partment served by the-coil; contrlolling How offrefrigerant through the coil and means Aresponsive to pressure supplied-fo `the eturn line ,fromanother unit controlling sai 'flowcontrolling meanss' v 4: A refrigerating system,including a -plurality ofindependent evaporator coils, 'supeach 'commony to all 'of to each coil and responply and return *lines,

partment served by the 4"coil, controlling How of refrigerant through the coil, and means responsive' topressure supplied to thelreturn l line 'from anothencoil controlling said'flowcontrolling means', the temperature and pres'- temperaturesand pressures; 5. l.AL refrigerating syste'myincluding a plurality of independent evaporator coils, each I adapted' for serving a separate'compart-ment,

n -single" supply vand return lines. having branches to said coils. means controlling/flow each 'adaptedheater,

`.evaporator coil foreach of a at different' 'insa-ogs 4of refrigerant through the coils, thermostats for the respective coils responsive at diferent temperatures, and means responsive to .different pressures in the'eturn line controlling the thermostats which are responsive to relatively low temperatures. 6. A refri erating system, includin a plurality ofinependent evaporator coi s,`each adaptedfor serving a separate compartment, single supply and freturn' lines having branches to said,` coils, means controlling flow of refrigerantthrough thecoils, including thermostats sive atdiferent temperatures, means responsive to different .pressures in the return line controlling thethermostats which are responsive to relatively low temperatures, and v means responsive to minimum pressure in the return line controlling 'flow of refrigerant through the supply line. A

v7. In combination with an evaporator coil, supply and return lines connected' with the coil, a normally open valve in the return line, means for closing the valve, a container for expansible pressure medium in communication with said means, an electric heater for said container, a'thermostat controlling said and means responsive to pressure in the return line controlling said thermostat.-y

8. A refrigerating system, including an. plurality ofseparate compartments, single supply andv return lines for the coils, each coil having an individual, normally open discharge va ve at i its outlet end, thermostatic' means localto each-coil `for closing 'the valve in response to .lowe .'ng temperature, and including an including forthe respective coils' respon-` i electric ircuit `provided with a switch, and f Vmeans local to each coil andv responsive to 9. kA refrigeratigl Systemaincldingpan evaporator coil for each of .a plurality'fof separate compartments, single'fsupply and return lines for the coils, each 4coil liavmgan4 'm'dividual, normally open discharge valve at its .outlet end, thermostatic means local to :each coil -for closing` the valve in responsej to e lowering temperature, and including an elec-` ,tric circuit provided with a switch, and means local to each coil and responsive/to` ressure in ithereturn line for actuating sai switchl independently" of; thermostatlc actuation thereof, the thermostatic and pressure responsive means of' the 'several coils`-being characterized tooperate at different tem eratures andjpress'ures for the purpose set Orth."-

x 410. A refrige'rating system, including a Vplurality of,l independent evaporator coils,`l 'each having a yleldiggly' opnmdlscharge plyvand rethe coils,

valve at its outlet end, singlesu turn lines connected with all o thermostatic means local to eacliicoilfor closingI its valve, including a local electric .cir-

insaess i cuit with its switch and lever mechanism for operating the fswitch, and a pressure relayv local to a coil and including a pusher member responsive to pressure in the return line f andoperable on said lever mechanism to actuate the switch.

l1. A refrigerating system, including a plurality of independent evaporator coils, eachv havlng a yieldingly open discharge,

valve at its outlet end, slngle supply and return lines connected with all v of the coils,

thermostatic means local to each coil for clos- Aing its valve, including a local electric circuit with its switch and lever mechanism for operating the switch, and a pressure rel/a local to a coil and includin a pusher mem er'responsive to pressure 1n the return line and operable on said lever mechanism to actuate the switch, the thermostatic means for the respective coils of a series being characterized to function at temperatures in a rising scale and the pressure relays to function at pressures in a. reverse scale.

12. A refrigerating system, including a plurality -of independent evaporator coils, each having a yieldingly open discharge valve at its outlet end, single supply .and return lines connected with all ofthe coils, thermostatic means local to each coil for closing its valve, including a local electric circuit with its switch and lever mechanism for operating the switch, a pressure relay local to a coil and including a pusher member responsive to pressure in the return line and operable on said lever mechanism to actuate the switch, the thermostatic means'for the respective coils of a series being'chvaracterized to function at temperatures in a rising scale and the pressure relays to function at pressures in a reverse scale, a compressor, means yincluding an electric circuit for operating the a switch controlling said circuit,

compressor,

to pressure m the reand means responsive 'turnfline less than that required for operationv of the coil relay of lowest scale for operating the switch to open the comsrssor clrcuit.

In testimony whereofI a JOHN F. H

m signature. I l

FMAN.

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