US2004474A

US2004474A - Compressor

Info

Publication number: US2004474A
Application number: US705907A
Authority: US
Inventors: Schaer Charles
Original assignee: Sulzer AG
Current assignee: Sulzer AG
Priority date: 1933-01-14
Filing date: 1934-01-09
Publication date: 1935-06-11
Anticipated expiration: 1952-06-11

Description

j June l1, 1935. c. scHAER Y y' v2,004,474.` Y COMPRESSOR f Y Filed Jan. 9. 1954 2 sheets-sheet 2 qa Y with a compressor `Patented` June 1,1, ,1935

Switzerland, as l 1 signoria Sulzer Frres, Socit Anonyme, Winopter-thnx", Switzerland` l ApplicationJanaxiafsseserial No; 705,901(

r r o y r o acclaim; 'I hi's oinventionrelates to a compressor. 1 In the Tormo shown herewithV it isapplied particu` larly to aj pistonV compressoia j y Ithasfor one obj other `object is to provide in connection with, ya compressor a plurality of variable` clearances. A further object islto provide in connection with a compressoig having a plurality; of variable clearances; unitary means `for,r controlling all of said",clearan'ces` andvfor'l controlling the move# ment of said unitary means in response to,a

variahle"` factor of vthe compressorsystem. A further, object of the `invention is to provide suchv a variableV clearancey system inua multi-stage compressor. Y Another object fof the l yinvention -isto provide automatic control 4means in aforml Carh A gramm 4o suitable for use under :the conditions. existing i ina refrigerating` systemand,alsolunderthe difL4 ferent conditions existingE in compressed air: powerdrivesfv f v In the form of the; invention a piston here illustrated, is arranged' to control ajprimary vari;

able'i'clearance` directly.: by/its own movement,Y and to control additional clearancesv also Vby ,its`` ow n movement, soA that the movement ofthe;

piston directlyprovides avariable clearance and also controlsthe''access*tov one or more-addi j tional clearance 'spa-ces.

I d p p I The ymovement,of.;tl'1is piston is controlled in thes'ystn.- This may; for example, be `the pres- As urelat the intake or-the discharge, or lit lmaybe any otherdesired variable factorfwhich varies u with the operation off the ,compressorsystem.4 "Otherj'objects will vapp ar'from timeto time in the specification and claims; i vThe invention-is illustra-ted more :or

atically ir1=y the` accompanying:` Whereinl-VA x Figure lgis a diagrammaticsectional i. viefW' showingaf'portion of the compressor and `the control mechanism; `i o m r o l `,F"ig`u1'e"2 is a transverse 'section,takeniat line II-II of1 Figure'lj Figure 3 `is aside View o to'Figure'l, showing amodied form'of the invention." i

`4 Likeparts are designatedby;lilfze.'` characters "servo-motor and Adetailed connectionsp are not ect to `provide fin,connection` a `variable clearance.` An# Y accordance with 1a varie, able f a'ctor which varies with the. operation of4 o f-the compressor; Aand Figure 4 isa sectional view generally, similar V urelLQA is' a' double-Walled cylinder; A1 is a plston mountedfrwithinthe cylinder for reciprof `catio`n;f, d, I Bjisahousing-member provided With-fa por- LUtionBPof reduced diameterfwhich ts into the cylinder A and; serves as a. cylinder head.` A

o o COMPRE'SsoItf f ,o charles sensei; Langenthal;

laterally extending Ailange B2,V formed, onV the f.

d housing B,A rests upon the cylinder A andserves as amme'ans offattaching` the housing tothe cylinderL'f The housing B is shaped to provide a? Ismall vcylinder B3, which; atits upper endVls l Blare provided with perforations B5, B6` and B7. As shown in'Figure 1, Vthese*p'erforationsor ports "enlarged as Vat, B4l to provide a double acting` 'servomotor'cylinder.' The Walls of the cylinderA ,aresituated at different levels, one abovefthe other; They communicate with clearancespaces B8, Bg and "B10, respectively, which clearances Yspaces are formedwithinthe housing B and are i withinf Cris a pisftonmounted to `reciprocate withinthe. j cylinder B3;4 Atits upper end itis provided wlthl anA ,enlarged piston C1 mounted .nto reciprocate j Withinv the"`enlarged cylindergportionl,` The? ,,,'separated'iromfeach other by partitionimembers, i

`asxshownl i'n `Figure 2." `.Ther'eare thus formed he housing B, and particularlygwithin ,them reducedA scctionfBl;` three separate,tclearance spaces, each ofwhich may be in communicationT with, the cylinder B3 through its respective ports` I. piston()l acts asa servof-inotorin agmanner which willbedescribed below.` There i is thus provided within the cylinder B4 afworking` space C?, beneaththe piston C1, `and a working space 03 i above it; "At its upper endthe piston (3,1` is pro` asv vided `with a rod C4' Whichlextends,` through theV partition memberCiwithinthe housing B. This j,

partition 'member serves toseparateythe clearance spaces `B8fB-" andBlUf'rom' the` remainder of the interior ofthehousing. v-A stuilingV box C pre- ,y vents` leakage from the-working space C3.`C"

isa pipe carrying a pressure uid from'any de- .sire'dT'so'urce.4 r C8, isa 'pipe `joined to the fpipe. u C7 and"` communicating with'theiworking `space C?. It' may be provided with a throttling mem.- Y

.ber C9.; Atits upper-send, and beyond theV pipe fC?, the pipe C7 communicates with the working spacev C5*V and vit mayv also throttling member C105 Y the working space `C2? and at the other end `in communication VL W'ithi-fthe 'annular' space' D1, formed Within the part D2; `which itself `lies jwithinrthe housing (B. The "annular space D1 be Aprovided with a. 0 `D is a pipe, at' one end in communication with y A2, the suction valve A9, the andthe discharge pipe A5.

. case A1.

75 same as that shown in is preferably continuous about the interior of the member D2. D3 is a pipe, at one end communicating with the working space C3 and at the other end communicating with an annular space D1 about the interior of the member D2. The member D2 is hollow as shown. It is provided with the two annular spaces D1 and D4 about its inner bore. D5 is a hollow slide valve mounted within the member D2 and provided with ports D9 and D1. D9 is a second hollow slide valve mounted within 'the member D2 and about the rst mentioned slidey valve D5. It is provided with ports D9 and D19. It will be noticed that the ports D9 and D1 are spaced closer together with respect to the length of the slide valve D5 than the ports D9 and D19, and thus only two of them rcan be in communication at one time.y

At its lower end the slide valve D9 is connected This lever is pivoted at `D12 and at its other'end is connected to the rod C1l of the piston C1. valve D5 is connected to a lever D19. This lever is pivoted at D14, and at D15 is slidably connected to the member D15 which is attached to the pressure-responsive member D11. The spring D19 is mounted within this member and at one end contacts the end of the other end contacts an adjustable abutment member D19, which may be attached to a screw D29. The screwvmay be moved in and out to adjust the position of the member D19 and to vary the compression of the spring D18. D21 .is an opening, preferably to the atmosphere, so arranged that the interior of thek member D11 is under constant pressure. D22 is the spacewithin the member D11. 1

Theupper portion 'of the housing B defines a space E, the partition member C5, and it is Within this chamber E that the cutoff valves D5 and D11 are mounted to move. Leading from the chamber E to some point within the system which is aiected by intake suctionof the compressor, is a pipe E1. The pipe E1might lead to a point aflected by the discharge pressure.

In Figure, 3 the cylinder A has a suction pipe discharge valve A'1 From the suction pipe A2 'the pressure-equalizing pipe the crankcase A1, jected tothe suction pressure of the compressor. From the housing'BAthe pipe E1 leads to crank- The gear-wheel pump C11, which is drivenfromthe/crankshaft of the compressor, draws the driving fluid from the cranlroase' A1 and delivers it into the pipe C1.

The form of the invention-shown in Figure 4 differs from thatY shown in Figure l, mainly in the fact that compression is accomplished in two stagesv and that instead of the single piston A1 of Figure l, a two-stage piston is provided. Thus in the form Vof the invention shown in Figure 4, there is a piston F which with an enlarged portion F1.

Y shown in Figure l, the operation of which will be described in detail below, is substantially the Figure 4. There are,

At vits upper end the hollow slide:

member` D11 and at theV extension from the pipe C1 the variation in the `may be in communication with the Y F3 through a Vport H19, which port is. con-` Y AGleads to which isv consequently sub-Y is provided y F2 is the cylinder within which the piston is mounted for reciprohowever, certain additional features necessary with the two-stage compressor which occur in Figure 4, which will be described below.

G is a housing member formed preferably integrally with the housing member B and serving to provide a number of chambers and controlling means. At the Vupper end of the member G is a chamber G1 within which is seated a valve G2, which is preferably carried on' a threaded shaft G3 bymeans of which it may be adjusted up ordown. GA1 is a second chamber formed in G. G5 is a hollow valve member slidably mounted ywithin the housing member G and adapted to project into the chambers G1 and G4. It is preferably provided with a laterallyextending ilange G5. l G1 is a spring mounted about the valve G5 and beneath the flange G6 and adapted, when free to do so, to hold the valve up in the position 'shownin .Figure 4, so that the valve G2 'is seated in and closes it. G8 is a lever pivoted within the chamber E at G9 and extending partially within the housing member G and arranged so that one end may contact the iiange G5 ofthe `valve G5. At its other end the lever G8 is-positioned over the rod CA1 which, inY the form of the invention shown in Figure 4, is extended upwardly so that it may contact the lever. A pipe VG10 forms an and` communicates with the chamber G4.

H is a pipe leading from the chamber G1 to the servoLmotcr housing H1. H2 is a pipeleading Yfrom the servo-motor housing tothe 'pipe E1. The pipe H2 maybe provided with a throttle H5. Mounted within the servo-inotor housing H1 is a piston H4. A spring H5 serves, when free .to do so, to hold the piston inits outer position. H5` is a by-pass pipe leading from the servwmotor housing to the pipe'H2. It will be noticed thatthe pipe H2 leads from the housing AH1 on one side of the piston and f housing on theV is a valve sternY that the pipe H5 leads from the opposite side of the piston. H1 attached to the piston H4 andy carrying a valve member H5. H9 is a clearance chamber which clearance space trolled by the valve H9.

It will be realized that whereas I have here-V with shown and described apractical operative device, nevertheless many changes might Vbe made inthe size, shape, number and disposition of f parts without departing from the'spiritvof my invention and I wish, therefore, that my showing be taken as in a sense diagrammatic.

The use and operation of thel two forms of the device are substantially the same. InI each case the output control is effective to cause the compressor to operate under'certain desired pressure conditions in some part of the system, and the output control is, therefore, an automatic, adinstable means to control may, for example, in the oase of a'refrigerating system, be responsive to the pressures in the low pressure section, the pressures existing in the intake manifold, which in theparticular showing herein described, would be the crank case of the compressor. Such control might also be used inconnection with compressed air power drives, where it would be desirable to deliver varying quantities within certain pressure limits. YIn

such a case, the control would bermade responsive Figure 4, the position oi the valve GZmay be ad'- Y insure such regulation. This i, the cylinder.

justed to cause thecontrol assemb1y,.designated i generally by H, to operate in` the proper phase relationship with the control apparatus desigf nated generallyas D; The maximum `volumetricr output of thecompressor occurs when there isthe smallest possiblefdead'space or` clearance within Inthis condition piston Cisfully..

lowered so that it completely nllsthe cylinderl B2 and'thus this cylinder is not available as addi-V tional clearance-space, andthe` ports B?, `Bf?l and` B7 are also closed by the piston C so that -the` additional' clearance spaceswhich they control are also closedf l Y y ,l

In4 order to change Vthe'output, the clearance'is changed. This is` Vaccomplished by 4moving the piston C back and lforth undera controltwhichis col'ordinated with the suction pressure, or,sorne other factor, so that theixnovernenir` the piston C is automatically varied in co-ordination with variations inthe suction pressureor discharge pressure, but remains locked against cyclic varia.-`

tionsin cylinder pressure. i Y

With the parts in the positions shown in Figure 1,'the piston C has been somewhat withdrawn` in the cylinder l?,3 so that a portion of `that cylin-` der is open and `thus furnishes' additional clearance. Thel port B5 is also partlyio'pen, and the clearance space B8 is thus available as` it is connected by the open port with Vtheworking spacein thecylinder. The pipe C'I issupplied C and C1 will not be movedbyv pressure variae tions within the cylinder A; I

l 'I`l'1epipeJC7 is dividedintotwo branches C? and C12,- connecting Withathespaces C2 and C3, in-lthe ordernamed. In these branchesarethe throttling valves C9 and C10, which permita small,

` regulated flow of liquid, but juponally demand for-increased flow, willproduce decided pressure differentials.` v

The space E within the. upperpart of 'theihousingB is connected by means of thepipe, E1

to theiritake of the compressor whichmay, for

i convenience sakeibe in Vtheenclosed crank space of the compressor and Eis thusrunder thefsuction pressure of thexcompressor andfas'that pressure varies; the` pressure within the space E .will vary The pressure within thespace E is eiTective upon" the member D11A to Vcompress it againstthe springjDw, or `to permitwit to'expandfunderthe influence fof the spring D1B depending.` upon whether the pressure Within. the. chamber E rises crfalls.'v VWithan increase. of pressure thememf ber D11is partially collapse-d and with a decrease of pressure it expands.` The space D2?, defined by the member D17, is open to some reference pres sure,` for example, the atmosphere, against which variations in pressure, either positive or negative, in the chamber E, will be effective to cause` movement of the member D1". f

When the pressure within the chamber E rises, due to a rising suotion'pressurethe `member D1rl is compressed and carries with it the lever D13,

Vthus lifting the slide valve D2 and bringing the port D11 in register withthe port D9 and thus Vopening the pipe D so that theluid `under pressure 'may flow from the space ,C2,V through the fpipe D, the `ports Dand D11 and the hollow in terior of the valve D5," into the space E, and

with liquidiunder pres`.

sure from any suitable source; Itmay benirom. a-pump, which is not shown. From this pipe the l uid under pressure is supplied to the working "spaces C2 and C3, respectively, below and. above` the piston C1, and soglong` as` thejpressure remains thus equalwithin thesetwo spaces, the pistons from there rit may discharge through the pipe E1. I Since' the portsDv an'dD9 arevlarger than the;

orice of the throttlng mer'nberffC9, inthe 'pipe C11,` the `pressure `inthew'space C2 drops and theVv piston C1 1willrespond 'to a pressureV difference y existing between space C3 Vand C?` and upon an` increase in pressure in C2fjover C2v will movedownward. This pressureV difference 'between C2 vand C3 is caused by the registeringof` the ports'D2 and- D11, which providefa free passage from the space C2'through theppe D into the (chamber E, and bythe outfofxreg'ister `orclosed position of i suiiicient 4liquid `cannot move intoV C2 to maintain pressure there, against :theffree exit established-V fthe 4vports D19 .and Dljwhich prevent free escape f iof liquid H from the A"space C3.` The liquidfsupply from the pipe Clpthreugh thejpipe C8 and C12, `of course, continu-es, but due to the throt'tlefC,A

through D, Deand D9. However, "liquid can pass# through` C12 andthe throttle C11? to build up pressure in C3,sri nce the exit`D31is closed; Thisover-4 balanced pressurelin C3 asfagainst C2 causesthej* piston C1 `to move downward.' Y c Itv is toibemnotedl that the throttling valvesC11 and C19 serve practically'fasv a hydraulic lock under a condition. when both exits'D and'D3 are blocked.` In other words, the'p'islton C1 willnotY move any measurableamount against"` `rapid"` fluctuation of, pressure, against its V'lower end duei l to the` damping Vor throttling effect existing inf" the circuit connecting the spaces C2 and C3. .As`

the pistons `C andgC1fmovedownwardthe clearl A ance space within the cylinder B1is'reduc'edV andl the portB5 is; also coveredby thevpiston C and D is' cut `off andV since pressurccan nolong'er escape from the working spaceC2, abaiancelbe-` tweerithe-pressure inthe space C2Aand that newpositionf, 5 e

Apsv af result of this new positionv `the f clearance space in ythe compressor has been reduced'and the output of the compressor is thus incr-eased.-v ,7, .Y

Upon the reduction ofgthe'suction pressure, the

pressure Within' the chamber E is corresponding-` ly @reduced and the `"springY Dfisagain .able-to expand' and to lmove ]them'ember,D1`1` inward.V This causes the lever D13 to swinginwardly about vpivot D14 and to move the slide 'valve D5,and the` port D7 .is brought` intoregister with" the port D10 and thusl the wayis opened for the discharge Qfthe pressure fluid from the workingspace 'C3` throughthe pipe D3, the ports D1o andDTand `the interior of the valve D5 intowthe chamber E. At

this time no dischargekcan occur through .the p'ipe' Df and thus the pressure in the working space thelspac'e C3 isat` once established and equilibrium 1 isestablished, with-the double pistorr1,C,rCl1 a` C2 is effective to raise the double piston`C1j C,

Vsincera free passage has been established in D3 and liquidi isrestrained by the v. throttle' C10 from maintainingpressure in the spaleefCQ` As the` pist-on C1y moves upward` itfjof` course, `raises fthe rodrjCi` and rotates the lever D11 lto` pulldowne ward the valve D8 `which-tendsto move theport l D11? out of register-withfthe port D'l and thus either vreduces `or entirely cuts loff the discharge of pressureud `from: the Vworlzinglspace` C2V l and B10.

' The operation of the .parts of the output conto' `the cylinder is the same.

through the pipe D3, so that a position of equilibrium is again establishedfor the piston C1. By adjusting thescrew D20 the load on the spring Dx8 may be set to control the action of the output control and particularly so as to control the time of opening of the ports into` the various additional clearance spaces, such as the spaces B3, B9

trol which appear also in the two-stage compressor'of Figure described for them in connection with Figure 1. The connection of the additional clearance spaces y Thus the cylinder B3 is connected with the upper end of the cylinder F4 in the same kmanner in the two figures and similarly the ports and the control of the ports B5, B6 and B7 is the same in the structures shown in the two gures. However, certain additional features are necessary in the multiple stage com- Thus the rod C4, which is attached to the piston Cl is preferablymade longer in the form shown in Figure 4, in order that it may contact the lever'GB. When this lever is contacted by the rod C4 it is shorter and is depressed against the flange G6 and moves it downward so vas to unseat the valve G2 and to open a passage to permitv discharge of the pressure agent from the'Y chamber G1 through vthe pipe H; Thus pressure is fed from the chamber within the'housing HY. With the valve G2 un- Y seated, the quantity of pressure'fluid which is discharged through ythe pipe H to the servo-motor is greater than that which can escape through the throttle H3 of the pipe H2 and thus the pressure of the liquid on the servo-motor piston H4 is sufcient to overcome the force of the spring H5 and` thus to move the piston back against'the spring and so to unseat the valve Ha and to open the port H10, and provide a path to the additional clearance space H9, which is added to the second stage of the compressor. f i

Byturning the screw G3 upon which the valve G2 is mounted, the member G6 can be raised or lowered against the spring G7 and thus the time when the lever Gwill contact the member G may be varied, so thatl the time of the opening of the additional clearance space H9 may be established at any desired pressure, and correlated to the conditions of the rst stage. It will be understood vthat the pressure fluid which passes from the chamber G1 is supplied through the pipe C" andthe extension C10 and ows rst into the chamber G4` andV thence, when free to do so,

through the hollow interior of the spring-supported valve seat G5. l

f There might be provided for'the second stage of `the compressor notmerely a single additional clearance space H9, but any desired number of additional l clearance spaces.

In the form shown and described, the compressor is adapted for use in a refrigerating system vwhere thecontrol will be responsive to changes occurring on the intake side of the compressor,

` which is also usually the low pressure side of the heat interchanger, and hence responsive to the ,heat load upon the system. The system obviously can be used in many other ways, and another such use, which would involve'a somewhat different arrangement, wherein the control would be responsive to the discharge pressures, would be that of compressed air power tool service, where varyingl volumes of air are needed within certain pressure limits'. It might also be used for liquefaction of gases, wherein the control would be responsive to 4, is the same as the'operation just.

G1 to the servo-motor v clearance chamber adjustable as to size and in y communication with the compression chamber,

Iadditional fixed clearance chambers, piston valve,

means for varying the rst named chamber and for bringing the second named chambers into.

communication successively with the compression chamber. i l

2.v In a compressor having a variable clearance chamber, pressure-responsive uid operated means for adjusting said clearance chamber, and means for holding said adjustment locked, said pressure-responsive adjusting means being in communication with and affected by variations in a pressure within the compressor system.

v3. In a variable clearance compressor, means` for varying the clearance, including an automatic pressure-responsive iiuid control, constant throttling and co-operative free passage yvalve elements adapted to control the flow of uid in the control means, `said pressure-responsive control means being in communicationwith and affected by variations in a pressure within the compressor system.

4. In a multi-stage compressor, a plurality of compression chambers, a plurality of clearance chambers associated with the compressionchambers, controllable valve means for connecting-the clearance chambers withthe compressionchambers and a pressure-responsive, automatic, unitary control for said valve means, said pressureresponsive control means being in communication with and affected by variations in a pressure within the compressor system.

5. In a reciprocating gas compressor of fixed Working stroke, automatic means for varying the yclearance volume responsive to pressure changes outside the compression chamber, and automatic means for holding any given amount of clearance volume constant against pressure changesoccurring within the compression chamber, said pressure-responsive clearance varying means being in communication with and `aiected-by variations in a pressure within the compressor system. i

6; In combination in a compressor, almain cylinder having a clearance space and a piston mounted to reciprocateA therein, and an output control for said compressor, comprising'a' plurality of additional clearance spaceV chambers, one of said chambers being 'directly in communication with said main cylinder,` and ports adapted tobring the said additional clearances into communication with themain cylinder, a piston mounted in said rst mentioned clearance chamber,'and arranged to move to vary the effective size of said chambenland means responsive to the suction of the compressor, for moving said piston to control. said additional clearance spaces.

'7. In combination'in a compressor, a main cylinder having a clearance space and a piston mounted to reciprocate therein, and an output control for said compressor, comprising al plurality of additional clearance space chambers,

-ber and arranged to move to vary the effective size of said chamber, and to control theopening of said ports, and means responsive to the suction of the compressor, for moving said piston to control said additional clearance spaces.

` 8. uenlcombination ina compressor; a main cyl-y e inder having` a. clearance spaceandf'a' piston.,

communication'withsaid chamber and adapted to bring thesaid additionalclearances into communication rvvitfh `the main cylinder; afpiston mounted in said lrst mentioned clearancefchamber and arranged to move' to lcontrol the opening of said ports, and vmeans responsive to the sucto, control 'said additional yclearance' spaces. 1 i Y 9. In'combinationin a-compressor, a-main cylinder having a clearance space Aand a .piston mounted .to reciprocate therein, and an .adjustable, automatic output "control for said compressor, comprising a plurality of additional clearance space chambers, one of said chambers being directly in communication ,with said main cylinder, and ports in communication with said chamber and adapted to` bring the said additional clearances into communication with the main cylinder, a piston mounted in said `iirst mentioned clearance chamber and arranged to move to control the opening of said ports, 'and means, responsive to the suction of the compressor, for automatically moving said piston to control said additional clearance spaces.

10.` In combination in a compressor, a main cyl- `tion `of the compressor, for moving said `piston inderhaving a clearance space, and a piston, an` `auxiliary cylinder adapted to furnish an additional clearance space for said main cylinder, `a piston in said auxiliary cylinder mounted to be moved to adjust the eiiectiveclearance within said auxiliary cylinder, and a pressure-responsive apparatus adapted to control and to vary` the position of said auxiliary piston, `said pressureresponsive apparatus means being in communication with and affected by variations in a pressure within 'the compressor system.

11. In combination in a compressor, a main cylinder having a clearance space, and a piston, an

auxiliary cylinder adapted to furnish an additionalclearance space for said main cylinder, a-

piston in said auxiliary cylinder mounted to be moved to adjust the effective clearance within said auxiliarycylinder, and a pressure-responsive apparatus adapted to control and tc vary the position of said auxiliary piston, said pressureresponsive apparatus being in communication with and affected by variations in the suction pressure ofsaid compressor.

12. In combination in a compressor, a maincylinder having a clearancespace, and a piston, an auxiliary cylinder adapted to lfurnish an `additional clearance space for said main cylinder, `a

piston in said auxiliary cylinder, mountedto be moved to adjust the .effective clearance within A said auxiliary cylinder, and a plurality `of addii tional clearance spaces, ports in the walls of said auxiliary cylinder and communicating with said additional clearance spaces, said auxiliarylpiston in its movement controlling the opening of said ports, and a pressure-responsive apparatus adapted to control and'to vary the position `of said auxiliary piston, said pressure-responsive apparatus means being in communication with and aiected by variations in a pressure within the compressor system. j

13. In combination in a compressor, a main cylinder having a clearance space, and a piston, an auxiliary cylinder in free communication with said mam cyiinderand adapted furnish an additional i clearancev space ftherefdr; 'a piston inl said auxiliary cylinder mounte'dfto? be 'movedfto adjust the eiective clearance within saidiauxiliary cylinder, and a plurality of 4additional clear-2.

ance .4 spaces, yports in the walls *of* ,said auxiliary cylinder uand communicating withsaid additional4 clearancespace's, said auxiliary pistonin itsjmovement controlling `the "opening of said ports, and a pressure-responsive apparatusadapted to Acontrol` and tovarythe positionv of said auxiliary piston, saidpressuref-respcnsive apparatus' means being .in communicationA withjand aifected 4by variationsjin a pressure within the compressor System `1 il l lifi. In 'combinationin a compressor, a main cylinder havingI a clearancev space, and a piston. an auxiliary cylinder adapted "to furnishl an additional .clearance space forl said -main cylinder, a piston said auxiliary cylinder mounted tobe moved to adjust the `effective clearance within-said auxiliary cylinder, and a pluralityof additional clearance spaces, portsin the walls of said auxiliary cylinder and connecting said additional clearance spaces `with said cylinder, said auxiliary piston in its movement controlling the opening of said ports, and a pressure-responsive apparatus adapted to control and `to vary the position of said auxiliary piston, said pres-V sure-responsive apparatus means being in cornmunication with and affected by variations in a pressure within the compressor system.

15. In combination in a compressor, a main cylinder having a clearance space, and a. piston, an auxiliaryv cylinder adapted to furnish `an additional clearance space for saidimain cylinder, a piston in said auxiliary `cylinder mounted .to

be moved to adjust the effective clearance within 4said auxiliary cylinder, and a` plurality of additional clearance spaces, ports in the side of said auxiliary cylinder connecting said addition-` al clearance spaces with said cylinder, said auxi iliary piston in its movement controlling the effective size of ,said auxiliary cylinder and the opening of said ports, and apressure-responsive apparatus `adapted `to control and to vary the position of said auxiliary piston,v said pressure-responsive apparatus means being in communication with and affected by variations in a pressure within the compressor system.

`16. In combination in a compressor, a main cylinder having a clearance space, `and a piston. an auxiliary cylinder adapted to furnish` an additional clearance space for said main cylinder, a piston in said auxiliary cylinder mounted to be moved to adjust the eiective clearance within said auxiliary cy1inder,and a plurality of additional clearance spaces, ports in the side of said auxiliary cylinder connecting said additional clearance spaces with said cylinder, said auxiliary piston in its movement controlling the opening of said-ports, and a pressure-responsive apparatus adapted to control the position of `said auxiliary piston, said pressure-responsive said main cylinder and adapted to furnish an adi ditional clearance space` therefor, `a piston in said `auxiliary cylinder mounted to be moved to adjustthe effective clearance within said auxiliary cylinder, and a plurality of additional clearance spaces, ports in'the side'of said auxiliary cylinder, Y ance vspaces with said cylinder, said auxiliary piston in its movement controlling the opening of said ports, and a pressure-responsive apparatus adapted to control the position of said auxiliary piston, said `pressure-responsive apparatus being in communication'with and affected by variations in the suction pressure of said vcompressor. i f s 18. In com ination in a compressor, a main cylinder having a clearance space, and a piston, an auxiliary cylinder incommunication with said main cylinder ,and adapted lto furnish an additional clearance-space therefor, a piston in said auxiliary cylinder mounted to be moved to adjust the eiective clearance within said auxiliary cylinder, and a plurality of additional clearance spaces, ports in the side of said auxiliary connecting said additional clear-M cylinder, connecting said additional clearance" spaces with said cylinder, said auxiliary piston in f its movement controlling the opening of said ports, land a v pressure-responsive apparatus adapted to control the position of said auxiliary piston, said pressure-responsive apparatus being in communication with and affected by variations in the suction pressure of said compressor. a compression chamber, a variable clearance chamber in communication with the compression chamber, additional xed clearance chambers, piston valve means for varying the first named chamber and for bringing the second named chambers into communication successively with the vcompression chamber, and means for holding said piston valve stationary against cyclic pressure variations in the compression chamber.

, a CHARLES SCHAER.