US2673025A

US2673025A - Compressor unloading means

Info

Publication number: US2673025A
Application number: US127016A
Authority: US
Inventors: Otto A Labus; Emil T Neubauer; Robert G Miner
Original assignee: Trane Co
Current assignee: Trane Co
Priority date: 1949-11-14
Filing date: 1949-11-14
Publication date: 1954-03-23
Anticipated expiration: 1971-03-23

Description

March 23, 1954 O A L US AL COMPRESSOR UNLOADING MEANS Filed Nov. 14, 1949 4 Sheets-Sheet l INVENTORS arm A. LABUS F l .EMJL z: NEUBAUER q' By ROBERT a. MINER ATTORNEYS March 23, 1954 o. A. LAIBUS ETAL 2,673,025 COMPRESSOR UNLOADING MEANS Filed Nov. 14, 1949 4 Sheets-Sheet 2 IN VEN TORS 01'1'0 A. LABUS EMIL T. NEUBAUER By ROBERT c. MINER ATTORNEYS March 1954 o. A. LABUS ETAL- COMPRESSOR UNLOADING MEANS 4 Sheets-Sheet 5 Filed Nov. 14, 1949 120512121 0. MINER ATTORNEYS March 23, 1954 o. A. LABUS ETAL 2,673,025

COMPRESSOR UNLOADING MEANS Filed NOV. 14, 1949 4 Sheets-Sheet 4 INVENTORS OTTO A. LAB

US EMIL T. UBAlER y ROBERT MINE ATTORNEYS Patented Mar. 23, 1954 7 COMPRE SS R-UNLOA=DIN GuMEAN S OttouimLh-busyEin-il T Neubauer; andRoliert G2 Miner L'aaCrosse, Wis, assignors -to The-Tranc CbmpanygzLazGTossc; Wis.

Application N avemlierl l, 1949; Serial No.1127,01;6

This; invention relates in to' compressors" and. to the. control of compressors: in reffigemtiontemsio f'fth'etype, having a compressor; a condem ser andfan evaporator: An .objectofthe-present invention is to provide'a compressor which may hetconti'olled-otto operate atits'maximum capacity: or: at. one of several? fractional amounts of its. maximum capacity without" any, substantial changeinzspeedi Another object off'thig invention is." to: provide 1 U a compressor iniwhich'" the: unloading "mechanism and? its" control are: energized'iby" the lubrication systemofthecompressor."

Ai third otij'ect 'of. ourinvention-is to provide-a compressor includingunloading; means therefor 1 5 which-isfincxpensive:to-manufacture and easy to assembleimd repair:

A- furtherobiectofour inventiomis to providemeansto control thefoperationzof the-compressoraccordiizg-tor conditions'of ,t-he:refrigeration-sys= 2U tem ofwiiich' it is'a part1 Still another-object of the-invention is toprovideacompressor'unloading mechanismwhicli is" responsive to the starting mechanism of the motornvhich'drivesthe'compressorr Otherobjects-and-'advantages of the invention-'- will be-clearl'y apparentas'tlie specification mm ceeds't'o" describe the" invention with refrenceto theaccompanying-"di'awings in Whicli--- Fig". l' is-a' seetionalview-, more ordess' diagram matic; of the apparatus of this invention. 3

Fig: 2%is a= cross-'sectional view of a cylinder" showing =a modifi atiorr of: my" invention.

Fig-L Wi a sectional 'vi'ew takenon tiieline-3- ofi'Fig. J

Fig;- e is' a top pl-an vevw of thecylinderlihezvoi the form of tlie irrventioirshown-in Fig: 1.

Fig: 5 is artop plan view 'of cylineler: liner 1 and valvelifting sleeve-*of-tlie form of= the inventioni of Figm? Fig; 6 Y alside view of the valvalifting sleeve? of' the form of the-invention sliowmin- FigrZE.

Visa-diagrammatic view ofl'th'e compres sorsmotor wiring anmthe compressor 'oilrpipingc 8:; is: a sectional. view: tazkem om an plane: through; the: axes: of: the: cylinders thee comepresent;

Referrineqznomto Eige'.l;..numeral; l Osdesignates thezhody orr-blockrofa theacompressor inzwhich is: rotatarbiy mountech, a: crankshaft: 12: which: isz: drivenzbyiramelectrieimotor on aminternal comebustiom engine: or other. suitable: nowerr meansz- Thezcomprcssor rmarm'haveaany desired mnnberzofi cylinders; amiiany desired arrangementzoftcylins 31Glaiins; (Cl. 230"2T old andTwelIIknoWn andidonctconstitute part'ofi' this invention. For, purposes.offillustration and description itfwilllb'e; assumedlthatlthe compres sor'has four cylinders.

Connectingrods M'are rotatably connectediat' one'endito thecranksliaft' l2 and they are pivotally; connectediat' the other end to each. ofithex pistons l6? Each cylinder com-prises acyIinder, liner 5 8 which is insertedifrom the" outer end.of' the: cylinder before the; valve plate 2B" and the; cylinder head 22" have been" mounted in place; Thecylind'erliner is supportedat'itsouter endbw the outerrwa'll"2ilofftlieicylinder and at'its inner end" by the wall 262 of the suction manifold 23" which communicates with the associated refrig= crating system througlia suctionline-30 whicliis" shown" diagrammatically. Thegsuction manifold 28. also communicates with thecrankcase. 32- throughaipluraiity of check valves 34; When thercompressor is'startedthe'pressure 'in'theisuction-manifold-'dro.p-srapidly andthe differenceiin pressureabetween: the" crankcase 32 and thesuc tion: manifold:- 28 closes the clieck'rvalve" 34'? and prevents a sudden"dropin'pressure-imtlie crank case which*wouldba'usetheoil to foam-excessive= 1yand--form, a" large volume? of foam. Dueto' leakagenf "gasffrom-thercrankcase '32to"th'e suc' tion manifold 28? the pressures'dni these" spaces. soon become substantially equal; and-the check valvetopens'to allow'any oil.accumulationimtl'ie" O suctionima'nifold to drainback into: the crankcase:

'Ilre-cy-linder liner l 8 has a" plurality of-suctiom valve 'ports"36 annularly spaced-around its wall; When' the*piston' Hi descends and the suction valve '3Bopens; as 'flows fromthe suction mani--- fold throug-h ports flfi into tliecylinder: The suc tion valve: 38 i -urged toward its seat by a phr rality" of coil spring-s10 whichare located in pockets inthe'valve mate-2w. When the piston-" I 6' ascends; the discharge valve- 42 opensagainst the action-of springs l' l positioneel in 'a discharge valve-= cage= 4451* A dischargevalveseat 48 is secured to' -the discharge valve cage 4-6=by a nut*50 Tlie discl'iarge-ga's from'the cliambers 52 of' thc heads fl is manifolded to a sing-ldisc-liargediiie 54*w-hicli isshoww diagrammaticallyo Eine 54 isconnected' to a condenser-53 whicli'in'turnis=con=- nectedto a;- liquid -receiver =58: Liquid from: the"- reeeiver fiowatliroughan expansion valvetfl toe heatexchangewfi 22 Tliemattento-be cooled snc-li" asgadrzor waterrflows through conduitifilin the die IGGfiOIITShQWII Joyrthe arrow Imordem to onnratezthe compressonattsubstane tiaili -'cons;tant; speed; but att. incrementszofl. its full capacity, we have provided means for holding one or more suction valves in open position to render the cylinders served by said valves inoperative in compressing gas.

Referring to Fig. l and Fig. 4, the cylinder liner I 8 has a plurality of holes 66 which support pins 68 for sliding movement. Springs 10 act against heads on the pins 68 to urge the pins downwardly away from the valve 38. A cylinder seal ring 12 is held against upward movement with respect to cylinder liner I8 by a snap ring 14 which engages in a groove in the cylinder liner I8. A cylinder member 16 is supported on the outside of cylinder liner I8, and it is further supported at its end by the lower wall 26 of suction manifold 28. The cylinder member 16 has a plurality of spring pockets which receive a plurality of springs 18 which act against a piston 80. The piston 80 supports a fiat ring 82 which in turn supports the pins 68. Cylinder 16 has a hole 84 through which oil under pressure will flow from fitting 86 when the cylinder is to be loaded. A cylinder is loaded by allowing the suction valve to operate so that the cylinder compresses gas. The oil flows from hole 84 through recess 88 in the wall of cylinder liner I8. From recess 88 the oil flows through holes 96 in cylinder 16 into the oil cylinder space and moves piston 80 downwardly against the action of springs 18. Downward movement of piston 80' allows springs 10 to move pins 68 and ring 82 down. When pins 68 move down they allow suction valve 38 to open and close in its normal manner and the cylinder is operating to compress gas or is what is commonly called loaded. Cylinder seal ring 12, cylinder 16 and piston 80 may all be provided with O-rings as shown. Said O-rings are of some flexible material such as rubber and prevent leakage of oil between the parts.

The operation of the control mechanism will now be described. A reservoir of oil 92 is contained in the bottom of the crankcase 32. The oil from reservoir 92 is used to lubricate the compressor and operate the unloading mechanism. An oil pump shown diagrammatically at 94 has an inlet pipe 96 extending down into the oil reservoir. It should be understood that the oil pump 94 may be driven in any suitable manner.

For instance it may be located at the end ofthe crankshaft and connected to be driven by the crankshaft. This is an old and well known F expedient. The oil flows from pump 94 to a check valve 98 which maintains a constant pressure in the oil system and returns the excess oil to the reservoir through pipe I00. valve 98 the oil under pressure flows through a pipe I02. Pipe I02 has a branch pipe I04-oonnected thereto. Branch pipe I04 supplies lubricating oil to various parts of the compressor such as the shaft seal and the bearings. The oil flows from pipe I02 to a solenoid operated valve I06 the operation of which will be described later. A pipe I08 conducts oil from the solenoid valve I06 to a valve body I09 of a valve indicated generally by numeral H0. The valve IIO is secured to the block I of the compressor and extends into the crankcase 32. The pipe I08 has a branch pipe I I2 which conducts oil to the unloading cylinder 16 of one of the compressor cylinders which is therefore always loaded whenever the solenoid valve I06 is open. The other three cylinders are loaded or unloaded according to the refrigerant requirements of the system as will presently be described. The pipe I08 is connected to passageway H4 in the valve body I09. Passageway I I4 connects with valve bore I I6 in the valve body From check.

I09. A plunger II8 has a. sliding fluid tight fit in bore H6. Plunger II8 has a small hole I20 drilled in one end for the passage of oil through the hollow center of nut I22. Nut I22 has a nozzle I24 from which the oil flows in varying amounts according to the positoin of screw I26 which is in threaded engagement with arm I28. The operation of arm I28 will be described later in the specification. It may thus be seen that a small quantity of oil is allowed to escape from bore II6 through hole I20, nut I22 and nozzle I24. The rate of escape of oil determines the pressure in bore I I6 tending to force plunger II8 to the left in Fig. 1. A spring I30 is supported on stud I32 which is in threaded engagement with the valve body I09 and urges plunger II8 to the right in Fig. 1 against the oil pressure tending to urge plunger I I8 to the left. The bore I I6 of the valve body I09 has three grooves I34, I36, and I38, As plunger H3 moves to the left in Fig. 1 grooves I34, I36 and I38 are successively connected with the oil pressure in bore Il6. Grooves I34, I36, and I38 are connected with pipes I40, I42, and I44 respectively. Pipe I40 is connected to one of the unloader cylinders 16 as shown in Fig. 1. In like manner pipes I42 and I44 are connected to the unloader cylinders 16 of other cylinders of the compressor. A pipe 146 is connected with the valve bore I I6 to provide for the return of oil to the crankcase 32.

The valve body I89 contains a bellows I48 which controls the position of plunger II8 as will now be described. The bellows I48 is clamped to the valve body I09 by a plug I50 which is in threaded engagement with the valve body I09. Inside the bellows is a spring I52 which bears at one end against an abutment I54 which is soldered or brazed to the end of the bellows I48. At its other end the spring bears against an abutment I56 which in turn is held against the spring by a screw I58 threaded into cover I60 of valve IIO. A cover I62 is threaded on a boss of cover I60 to provide a seal for screw I58. The chamber I64 in which the bellows I48 is mounted is connected by a passageway I66 to the suction manifold 28 of the compressor whereby the pressure on the outside of the bellows is substantially suction pressure. The interior of the bellows I48 is connected by a passageway I68 and a pipe I10 to a pneumatic temperature controller I12 which is connected to a source of air under pressure I14. A thermostatic bulb I15 is supported in the conduit 64 in the path of the matter leaving the heat exchanger 62. The thermostatic n bulb I 15 is connected by tube I16 to pneumatic temperature controller I12. The pneumatic temperature controller I12 is a standard device well known to those skilled in the art, and since it forms no part of the invention per se, its construction will not be described in detail. A pin I11 is slidably mounted in valve body I09 and is engaged at one end by abutment I54 of bellows I48. The other end of pin I11 engages arm I28 which is pivoted to bracket I18 by pin I which extends through the bracket I18 and the arm I28. Bracket I18 is fastened to the valve body I09 in any suitable manner. The bracket I18 and the arm I28 have a'plurality of holes for receiving the pin I80 to provide for moving the pivotal point of arm I28 by shifting the pin I80 to a different set of holes. A member I82 is secured to bracket I18 in any suitable manner as by spot welding and supports a spring I84 which at its other end presses against the arm I28. Referring 'to Figure 3, the plunger 8 has crowns:

5 iourrrouha bottomed grooves l ss which-are enraged my halls 488 which in turn are urged to seat in thegrooves l 86' :by the-s rings 1st which are held 'in place by screws L92 which are in threaded engagement with the valve body its. Balls 8 by engagingin grooves "I86 insure that lunger H8 will move in "definite steps to compIetelynneoi/er or compietelyclose each or the grooves 134, "136-, and 138 to oil pressure. Eig's; 2; 5, and 6'='sliow a'modifie'd form o'f'the hydraulic valve liftih'g meolia'nis'ln. In this form orthe'invention-a' piston [94in the form of cylindrical shell surrounds the cylinder liner l8 and is 'm'ou ted for slidin'g movement thereon. Piston 1 94 has at i one end a plurality of fingers 196 whichextend upwardly through the suction valve ports fl -to engage the suction valve -38 and hold it open during pertain conditions of Operation 6! the'compre'ssoras w'illbe described. Arubber O- lih'g 198 is supportedon a flange 2-00 of the piston I94 and prevents leakage of=oil around tlie pistor'i. -A-ring2-02 closes theendof'the cylihdera riibber o-ring 204 prevents leakage aroundthe ring 2 02. Therin'g Z'D'Z isheld against upward movement by a spring snap ring 296 which by its resiliency engages in *a groove 293 in thewall 2-6 ofthesuction manifold-28. The snap rlng fllfihas two ears 2 l which are 'pressed toward "each other to mountthe snap ring 2% in the-groove 208--or'to*remove it therefrom. A spacer *ri'ng "2 l2 channel "shaped in cross-section is mounted =between the' O-rings 1'98 and 294 to prevent- -the 'o rings I 98 and 204 from moving to a position at which 'theywould close the oil supply-openingfll. Springs 2ft are supported :7:

in -"noles wali fliand act against theflange 21m to urge-the pistoniM upwardly against the valve 38. When the control mechanism admits oil under pressure 'to pi'pe 'l"' l0,-the' oil 'flows through openlng fl land 'forces-O-rin'g [9t and piston 9t dowhwardlyto allow the suction'yalve 38 to operate its normal manner.

F igfil is adieigrammatic view showing the Wiring of the compressor "motor starter and the oilpipingoftheeompressor. For the purpose of explanation will be assumed thatthe compressor is driven by *ajthree phase motor 2ft having atwo step primary resistance reduced voltage star'te'r. A conventional motor starter is show'nhaving threeresistors 22c bridged by a three pole contactor having contacts 222. This contaetor anauxiliary contact 224whi'ch is'in series with-" the s'ol'enoid valve-106. additional threepole contactor havingcontacts 226 is conneeted to supply current from-the supply lines 228 tothe resistors 220. The-contacts 226'have anoperating coil notshown and the contacts 222 and-224 also have an operating coil not shown. Conventional auxiliary circuits provide the sequence of operation "by which contacts'2'26 are first closed, and-after the motor has started,

contacts

222 and 224 are closed. I

Whenthe compressormot'or 2 I8 is started -the don'tacts' 228 "close "and "current "flows from the supply lines through the resistors 22a to the motor 2l8. During this period,

contacts

222 and 224 are open and no current is supplied to the solenoid valve I06 and solenoid valve I06 is therefore closed. With solenoid valve [06 closed oil pressure does not reach any of the unloading cylinders 16 and the compressor is completely unloaded. As the timing device in the auxiliary circuits completes its cycle, the

contacts

222 and 224 close, short circuiting the resistors 220 and supplying motor 218 with current directly from 6 the :lines 22 8. When icontact nillicl'osea'ithe -ia'ifi cuit to solenoid valve :l 06"is:icomp1eted and isole noid valve 106 opens allowing oil to reach iline H2 and valve M0 to loadi all ofithe compressor cylinders.

I Modus'operandi Having thus described the details of construction of the apparatus, the'manner of operation will now be described:

When the compressor motor starting contacts 225 are closed,fthe"solenoid valve W6 isnotenergized andlines HJBan'di l2 do not receive any oil. Noneiof .the valve lifting cylinders 16 is receiving oil. Consequently the springs "18 acting'through pistoneil, rings 82 and pins 68 "are holding the suction valves 38 'ofall cylinders in open position. When the motor starter completes its cycle, solenoid valve iii-5 is energized and oil pressure reaches lines 1% and H2. "Since the suction pressure inmanifold28 ishigh dur-. ing starting, the bellows MBIis compressed and screw 12% closes opening in .nozzle I2 3 'to raise the pressure in'valvejboreji l5 an'dflmove plunger M8 to itsextremepposition'tothe leftas viewed it in Fig. 1. Wl'thth' plunger us in this positio oil'fiows from pipe J08 through passageway "Hi l and into grooves 13$,I'3fi and I38 and then'into pipes Hi0, I'42'andi4. Since the pipes'HZ. 8%, M2, and HM are each connectedtooneof the fluid cylinders 16 serving each o'fthelcompressing cylinders E8, the pistonsiill of the cylinders are all forced downwardly by oil pressure, and the springs 10 force the, pins 5'3 downwardly so that the suction valves to are allowed to operate in 'theirnorm'al manner so thatall the cylinders are loadeda'ndthe -compressor is operating at its full capacity. After the compressor has been operating fora period'of time, the refrigeration system served by the comprese sor becomes cooled to the design temperature an'd'the suctionpressuretends to falllbelow the design pressure; drops below 'apredetermined point which may be set as desired "by adjusting screw 158, the bellows Mil expands and acts through pin 151"! and arm 828 to move screw I26 away from" nozzle i2 3 allow a sufficient amount of foil to -pass through nozzle !2'4"to reduce the pressure in bore =5 l etc the point atwhicnspring -i3ilmoves plunger 1 iii to close groove "I33 from oilpressure'an'd'open pipe Hid to the drain 1'46. The cylinder "served by pipe HM therefore becomes unloadedjbecause springs '18'acting through piston 8i}; ring"8 '2,and pins 68 holds thesuction valve 49 open. If the capacity'oithe three loaded cylinders is greater thanthe'load'on the refrigeration system, the tendency of the suction pressure to drop will continue, and thebellows i lil'will expand 'iurther'until pipe MZ'is cut on; rro'm'the oil pressure and'connectedto the drain pipe 'ie'ii. Two of the four cylinders have "thus been unloaded. If the capacity or thetwoloade'd When :the suction pressure matic -temperature controller I12 to operate in a manner which will now be described. By Way of example let us assume that the unloading control is set to maintain a suction pressure not lower than 40 pounds per square inch. The pneumatic temperature controller I12 will vary the suction pressure above or below 40 pounds per square inch as the temperature of the matter leaving coil 62 falls below or rises above a desired temperature.

Let us assume that the bulb I15 is subjected to a temperature above that which is desired. The pneumatic temperature controller I12 will reduce the pressure in pipe I and will therefore reduce the pressure inside bellows I48. With a reduced pressure inside bellows I48 the suction pressure must drop below 40 pounds per square inch to unload the compressor. Therefore a suction pressure below 40 pounds per square inch is maintained and the lower suction pressure causes the coil 62 to do more work and to bring the temperature of the matter leaving coil 62 down to the desired temperature.

Although we have described in detail the preferred embodiments of our invention, we contemplate that many changes may be made without departing from the scope or spirit of our invention, and we desire to be limited only by the claims.

We claim;

1. A compressor comprising a plurality of compressing cylinders, a common suction chamber and a common compression chamber, each of said compressing cylinders having associated therewith a suction valve through which gaseous medium may be admitted from said suction chamher and a discharge valve through which compressed gaseous medium may be discharged into said compression chamber, and spring means to force the suction valve to open position, fluid pressure means for overcoming said spring means, said fluid pressure means comprising an annular piston slidably mounted on the outer surface of said compressing cylinder in fluid sealing relationship therewith and providing an an nular fluid chamber between said annular piston and the outer surface of said compressing cylinder, fluid pressure creating means, means comprising a valve for conducting said fluid pressure from said fluid pressure creating means to said annular fluid chamber, and means responsive to the pressure in said suction chamber for controlling said fluid pressure conducting valve to cut off the supply of fluid pressure to said annular fluid chamber.

2. A compressor comprising a plurality of compressing cylinders, a common suction chamber and a common compression chamber, each of said. compressing cylinders having associated therewith a suction valve through which the gaseous medium may be admitted from said suction chamber and a discharge valve through which compressed gaseous medium may be discharged into said compression chamber, means comprising an annular piston slidably mounted on the outer surface of said compressing cylinder in fluid sealing relationship therewith and providing an annular fluid chamber between said annular piston and the outer surface of said compressing cylinder, valve engaging means supported by said annular piston, spring means acting against said annular piston and tending to move said annular piston and said valve engaging means toward said suction valve to force said suction valve to open position, fluid pressure creating means, means comprising a valve for conducting the fluid pressure from said fluid pressure creating means to said annular fluid chamber to force the annular piston in a direction away from said suction valve against the force of said spring means and means responsive to the pressure in said suction chamber for controlling said fluid pressure conducting valve to cut off the supply of fluid pressure to said annular fluid chamber.

3. A compressor comprising a plurality of compressing cylinders, a common suction chamber, and a common compression chamber, each of said compressing cylinders having associated therewith a suction valve through which gaseous medium may be admitted from said suction chamher and a discharge valve through which compressed gaseous medium may be discharged into said compression chamber, and spring means to force the suction valve to open position, fluid pressure means for overcoming said spring means, said fluid pressure means comprising an annular piston slidably mounted on the outer surface or said compressing cylinder in fluid sealing relationship therewith and providing an annular fluid chamber between said annularpiston and the outer surface of said compressing cylinder, fluid pressure creating means, means comprising a valve for conducting said fluid pressure from said fluid pressure creating means to said annular fluid chamber, fluid means for moving said fluid pressure conducting valve to closed position to cut oil the supply of fluid pressure to said annular fluid chamber and means responsive to the pressure in said suction chamber for controlling said fluid means.

OTTO A. LABUS. EMIL T. NEUBAUER. ROBERT G. MINER.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 2,028,577 Kuhl Apr. 28, 1936 2,274,337 Bitter Feb. 24, 1942 2,304,999 Gonzalez Dec. 15, 1942 2,329,931 Neeson Sept. 21, 1943 2,387,117 Buehler, Jr Oct. 16, 1945 FOREIGN PATENTS Number Country Date 461,838 Great Britain 193'1