CA2075548A1 - Swash plate type compressor - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A swash plate type compressor includes a cylinder blocks having a crank case which communicates with a suction port and a plurality of bores formed therein. The ends of each bore are covered with a pair of housings. The bores communicate with discharge chambers. A drive shaft is rotatably placed within the cylinder blocks. A swash plate is rotatable in the crank case, and is mounted coupled to the swash plate, and are reciprocate, a refrigerant in the crank case is sucked into bores. A passage for transporting the refrigerant between the discharge chambers is formed along the axis of the drive shaft. Seals are provided between the cylinder blocks and the drive shaft for sealing the gap between the discharge chambers and the crank case.

Description

207~ 8 SWAS~ Pl~Tg TYEE COM~RE;SSOR

l3ACKGROUND OF THE I~3NTION

This applicaticn claims the prioxity ~f J~p~nese Patent Application Nos. 3-200962 filed August 9, 1~91, 3-201635 filed August 12, l991, and 3-225989 filed Sel?tember 5, 1991, which are incorporated herein by re~rsnce.

Field of the Invention The pre3ent invention relates to an im~?~oved swash plate t~pe ~omp~es~or sui.table f or use in a vehicle air conditioning sy~tem .

DeecriD~ion of th~ Re~ Qd Ar~c Ja~ e~e Unexamlned P~tent Publica~ion tlo. 3-925~7 ~isclo~ec~
~ swash plate type oompressor which includes a front ~nd ~ear cylinder b1Ocks. A c~an~ case i~ connected to a refrigexant .

:-, ' ' ' ~Q7`3~

sucti~n port, and i~ located at an intarf ace sec~ion between the fr~n~ and raar cylinder h~loc~k~:. Each cylind~r blo~:k har a d ~tal ~nd which i~: covared by a c~orr~aeponding hou~ing ~:Qction~ A ~x~n~ ~lv~ plate i~ c~inpoe~ed intermeditlte t.h~
S front cylinder block ~nd the ~ro3nt housir~g section.
Si~nilQr~y~ c~ r~ lve pla~¢ i8 dispo3~d intermed~te the ~c~r cylind~ bloc~c ~nd the rea;r housing ~ection. ~ach hou~;ing ~ctlDn~ include~ a. suc:tion cl~ ber and a di~charge ch~nb~r. The diYch~rge chamber leads tc~ ~ refrigerant lo di~ich~rge port:.

drive 6haft xotatably enter6 th;rough an axial opening in the front arld rear c~' ~nder block~ . A ~wa~h plate i~ flxedly mounted on th~ drive ~haf~ and is rotatabl3r di~posed within thc crank cafe. ThQ valve ~late~ incl-~de suction port~ which connect the ~u~tion cha~ber~ to a plurality ~ cyli~der~, via coxr~ponding ~uctior~ valves. ~ach valv~ plate al30 ha6 a di~charge port which connects each discharge chamber with eaah c; l~nder via a discharge valve. Eaoh ~ylinder bl~ck ha~ a plurali~y of suction pa6~age~ which cons~ect the erank ca3e to the front And rear ~uction cham~er~, and ~ di~charge pa~age which interconnects the front and rear di~ch~rge chamberJ.

The disch~rge passaqe is located such th~t the di~charge pa66~ge doe~ not intsrfer~ with the ~uctlon ~a~gage and thu crank cuse. Due to design re~triction~, such a2~ th~ llmltod outer di.m~nsion~, the di~haxçle S~a6sage has to ~e po~ition- d 2 ~ 4 8 close to the ~uct~on pas~age. In thi~ arrangement, howe~er, the refrigerant flow~ ~rom the refriger~ti~ circuit ~o ~ho crarlk ~-a~e and thQ ~uctic-n p~sc~ge>, through the ~uction por~.
~hQ refrig~rant ab~orbs h~ t f~om the hot c~nd comprooaed refxig~rant ~l~wing through the di~charge passagè. The ~frigara~t i~ compre~cd to ~ hi~her te~per~tur~ an~ i8 then di~ch~q~d. ~ a result, ~he clrculatlon Or the discharged ~eated refri~erant increase3 the 14ad on the ~efrigerating circuit, thus lowering its cooling ability and the overall ef~lciency of the compres~or.

SUMNARY OF TEE INVENTION

It i6 ~her~oxe an obje~t of the pre3ent invention to minimi~e the o~erheating ~f ~ refrigerant, while 6ecuring an airtight sea-ing of the di~aharge cham~er.

To ~chieve ~he foregoing objects, the 6wa~h plate type compressor of the present inven~ion includes cylinder bloc~
having a cran~ case ~hich ~ommunica~e~ with a plurality of ~uction ports ~nd ~ pluxality o$ bore~. 80~h ~nd~ of each ~oro are ~ealed with a pair of hou~ings. The bore~ c~mmunicate with the di6charge ~hambe~a. A drive ~haft i~ rotatably pllced in ~he ~ylinde~ ~lvcks. A swash plate i~ mounted on the drive sha~ within the cr~nk cas~.

: A plurality of piotons are drivably cou~led to the 6wa~h 2~7~ ~8 pl~te, ~nd reciprocate in their refipe&tive borG~. ~s the pistona reci~rocate, the refrigsrant in the cxank c~e ic sucked into each borQ t~ b~ compr~ed t~Qrein, and th~
oompres~ed r~frigor~nt i~ di~oharged int~ ~he di~oharge chamber6 ~rom ths bore3. A pa~sage for feeding the ref~iger~nt beewe~n the di~eh~rge ch~mbe~s i~ ~ormed along the ~Xi8 o~ the drive ~haft. Seals are provlded between the cylind~r bloc~s and the dri~e ~h~ft, to interC~p~ ~he communications be~ween the discharge chamb~r~ and the crank c~se.

~RIEF ~ESCRIPT~ON O~ T~ l)RA~INGS

The in~ention, together with object6 and advantage6 thereofr m~y best be undexstood by reference to th~ following descriptLon of th- presently preferred embodiments together with tho accompanying drawing~ in which:

Fi~. 1 iB a cro66-section~l view of a æwaæh plate type compres30r according ~o a flr6t embodiment oi the pre#ent invention;

Fig. 2 i~ ~ cross s-ctional v~ew o~ ~he compres~or in Fi~. l tak~n along line 2-2;
Fig ~ 3 iS an enlarg~d cxo~-aectiona~ v~ew illu~traiing part of a seal ~or u~e in the oompre660r of Fig. l;

~07.i.~8 s Fig, 4 i~ an enlarged cros~-~ectional viaw showing a m~dification of the ~eal o~ ~ig. 3:

Fig. 5 ic an onlarg~d c~o~-e-o~ional view illu~trA~ing another modi~ication of the ~eal of Fig#. 3 And 4, Pig . ~ crc>a~-~e~tional v~ ew of ~ ~wa~h E,late type comp~e6~0r acco~dlng to ~ ~ccond embod~ment of the ~re~ent in~rention;

Fig. 7 i~ a c:rosæ sectional v~e~ of the compres30r of Fig. ~, taken along line 7-7;

~ig. 8 ~ a graph showing the relation~hip between th~ cro~-sectional area o~ a dischArgo pas~age and th~ volume ef ~iciency;

Fig. 9 .is a crosE; I;ection~l view illustrating the di6position of the di~charge ports and a di~charge pas~a~e in a convontional co~pres~or;

Fig. 10 i~ a ~rosR-sectional side ~iew or a swa~h pla~e type compre6sor accor~ing to a thixd embodime~t of thc pres~nt inve~tion;

Fi~. 11 is a cro6~ 6ection~1 view of the compres~or of ~ig.
10, tak~n along line 11-11;

~ ...... : ' ' ~

2 0 ~ 8 Fig. 12 is a croa~ ~ectional view of tha c~mpre660r of Fig.
10, taken along lin~ 12-12 Fig. 13 i~: ~ c~:o~ eoational ViGW of the compre~l~r of Pi~.
10, tak~n along line 13-13;

Fig. 14 iG ~ C~ g sec~lon~l view of ehe ~ompressor ~f Fig.
10, taken aiong line 14-14;

~ig. 15 is a crc~88 ~ectional view of the coD~pres~or of Fi~.
10, tak~:n along line 15-15;

Fig. 15 i8 a cro~s 6ectional view of the compre~3sox of Fig.
10, taken along l..~le 16-16;

~ig. 17 is an enlar~e~ cross-~ectional 6ide view of a d~scharge valve and a f lo~t valve f or use in the compre~sor o~ Fig. 11;

Fig. 18 ifi a oros6 sectio;~al view of the compre6~0r ~f Fig, 17, taken along line 1~-18;

~ig. 19 is ~n explo~ed perspectLve vlew of a swash ~late, a two-head~d pi ~ton and ~ suction Jalve ~or u~o in the ~onlpxe6ffor o~ Fig. 11; and Fi~. 20 is a cxoss-l3ectional ~ide view of the entiro .. . . . ..

2 ~ 7 ~

compr~ssor according t~ ~et an~t~er embodiment according to t.he present invention.

D~TAILED DES~ ON 0 s A ~iret ~mbodim~nt of the pr~s~n~ in-J_ntion will now be de~cri~ed with r~fer~e~ to the ~c.comp~nying drawin~.

Fiq. 1 illu~trate~ ~ front cylind~r block 101 and a rear c~linder ~lock 102 which a~e combined with each othe~ in axial align~.ent. to form a unita~ cylindex block. A crank cas~ 104 is ~ormed intexmediate the front and rear cylindex ~lock~ 101 and 102, and communicates wl~h a xefrigerant inlet port 103.
The ends o~ the unitary cyllnder block ~re clo~ed wi~h ~ front hou~ing 107 and a rear hou~ing 108, via ~Alve plate~ 105 and 106 re~ectlvely. ~ ~ho~n in Fig~ 2, a ring-~haped front ~uction chambers lOg i~ formed in the inner peripheral portion of the front housin~ 107, and a COhcentric front diacharge chamb~r 111 i~ formed in the inner central section. The fsont discharge chamb~r 11~ enclos~6 the outer surface o~ a drive ~ha~t 11~. Similarly, a r~ar suction cha~ber 110 .16 formed in the inner periphor~l portion o~ the rear housing 10~, and a concentric rear di~charge chamber 112 i~ formed in the cent~al section.
~he drive ~haft 118 i6 $itted xotat~bly within two axial bores lOlA and 102A o~ the cyli~der bloc~ 101 and 102, vi~ radi~l 207c~ 8 ~earings 114 and 115. Thi~ drlve ~h~3ft 118 pen~tr~te~ th3rough an opening 105c in the front val~Je ~late 105, ar.d extend~
out~ardly through the outer end of th~ front hous;in~ 107 Vi~L
a ~eal ll9~

A ~w~h pl~te 123 i~ rotl~t;~ly di~p~ d in tho c~ nk ca~;e 104, And i~ 6~o~:urcly n~ nte~ o~ the drive ~h~t 118. ~rhi~ ~3walPh pl~ 23 i~ onnected to both cylinder block~i }01 and 102 by means o~ thrust bearing6 121 and 122. The front cylinde~
block 101 includ~ a plur~lity of axially extending bores l~la which ~r~ arranged equidi~tantly a~ und the drive ~haft 118.
Similaxly, the xear c~-linder block 102 ha~ a plurality o~
axially extending b~res 102a which ~re ar~anged es~uidistantly arollnd the drive ~haft 118. A two-he~d pi8ton 125 reci~rocate~ in each pair o~ the bore~ lOla and 102a. Each piston 125 is engaged with the swash pl4te 123, vi~ a pair of fihoes 1~ 4 .

The suction port 105a is formed in t~.e ~ron~ v~lve plate 105, ~nd connect6 the front ~uction cham~er 109, via a ~uction valve 126, to the b~re~ lOla. Similarly, the r~ar va~ve pl~t~
106 has a rear ~uction port 106a form~d therein, to connect the re~r ~uction chamber 110, vi~ a 6~ction valv~ 127, to the bores lC2a. ~he val~e pla~e 105 al60 lnclude~ a discharge port 105b which connect~ the front di~charge ohamber 111, via : a discharg~ v~lve 130, to th~ bore~ lOla.

~2 ~ r~
g 5imilal-ly, the rear valv~ plate 106 int lude~ a dischar~e port 106b whit h ~onnect~ th~ rear diecharge ch~nb~r 112, ~
discharg- valve 131, to thc bore~ 102~ plurality of sauc~ion p~scges 132 ~r~ ~ormed along the outer peripheral portions ef the cylinder block6 101 and 10~, in order to connect: the crank ca~e ' os to both ~u_~on cbanbers 109 and 110. P~ plurality o~ ~t>lt~ 133 are i~d into the ~e~pective suction pa~sage~ 132 te conn~ct the front and rear housing3 107 and 108.

A di~charge port 128 i~ ~or~ned in the rear hou6ing 108, and i~ gener~lly ~ligned with d~;charge pa~sag~ 140. ~rhe di~charge ~ort 12~ communioates with the rear di~c:harge ch~er 112. The di~cha~ge chamber 112 al~o con~uni~ate~ with the a~ial bore 102A of the rear cylind~r block 102, vio. o.n opening 106c in the valvs plat~ 106.

;rhe di3charge passage 140 in the pre~ent embodiment i8 axially ~ormed within the dri~e ~haft 118. The di6charge ~assaQe 140 has one of it6 ends colmnunicating with th~ axi3 bore 102A.
At the othex ~nd of tbe di~charge pas6ac~e 140, a pluralit~ o~
th~ough holes 140a are formod in the driv~ sha~t 118~ and extend in ths radial direction. ~be through holo~ 140 collununicate with the disoharge pa~age 140 and the dlsc:hargQ
chamber 111 .

Ring-sh~ped ~eal~ 141 are ~itted ln th~ axial boz~3D lOlA a~d 2 0 7 ~ 8 ~.Q2A of the cylinder ~locks lol and 102. Each of the ~e~ls 141 has a ~enQrally U-shaped crc~:s ss~ction, a~ hc~wn in Fig.

3, and haq i~:~ op~ning fa~e th~ di~chArge oho~er~ nd 112. Du~ to th~ high pre3eure in the diach~lrge cb~ rs lll and 112, th~3 seal6 141 are ~orced ag~lin~t the irlr~er ends of tho reflpec~ive ~Ixio.l boreo lOlA 2~nd lO~A. The seals 141 are in cloao c:on~lct with the oute~ 6urface of the drive sha:l~t 118 and th inner walla of thc ~x~ ~1 bor~s lOlA and 102A. Thi~
sealinc.J arrangeme,nt ~eals the discharge chunbers l~l and 112 o crank ca~e 104, prevents leakage therebetween.

q'he ~efrigerant tha~ cllculates back to the ~ pre~sor via the inlet port 103 from an ex~ernal xefrigerating ci~cuit, ~1QW8 into the crank case 104. Then, the re~rigerant is guided, via the indlvidual ~uction pa~3agea 132, to the f~on' ~nd rear suction chambers 109 and 110. Meanwhile, the individual pistons 125 re~iproc~te in the re~peative boree lOla and 102a, via the swash plate 123 which rotate~ ~ogether with the dxiv~
fihaft 118.
~ccordingly, the r~frigeran~ in the suc~lon chambers 109 and 110 ~r~ dxawn, v~a ~he 6u~tion portq 105~ and 106a o~ the ~lva plates 105 and 106, into those bores lOla and 102a whose volumes are increa~ing. The compressed rQfrigerant iB
discharged, via the di~ch~rge ports 105b and 106b of th~ lve plc.tea 105 an~ 106, to the front and rear discharge ck~ro 111 and 172, from tho~e bores lOla and 102a wh~se v~lumo~ ~ro 287:ti~i~8 dec~reasing .

I!h~ c4n-pro~d rof~igerant di~aharqed into the front diach~a~g~
chambal- 111, ia drown ~ the through hole~ 140a into the di,~haxge pa~ag~ 140. The xe~rigerant urther flow~ ia the openiny 106c, ~nd joins ~ha compressed r~rr1gerant in the xear d~charge ch~er 11~. T!le combi~ed refrigerarlt i6 dis~harged through ~he dischargæ port 128 to an outer refrigerant circ~lit including a condenser (not ~ho~n).
Particularly, the di6charge pa~s~ge lgO i~ formed in tha drive ~haft 118, ~o that the refrigerant flowing- 'hrough th~ ~rank ca~ 104 and tho suction passages 132 i~ ~ufficiently in~ulated and remotely di~posed fro~ the hent fr~m the di~ch~rge pa~a~e 140 {hot xefrige~nt). Exp~r~ments have shown that, whsn the temoeratu~e of the ài~cha:cged refrigerant with re~pect to the nwnber of rotatic~n~i of the co~npressor of the pres~nt invention is co~pared to the temperatl~re o~ the refrigerant in a conventional compressor, the temperature of the present compre~or i~ about 5 ~ c lower at a spe~d ranging from 1000 to 300~ rpm.

Furth~r t sincs ~h~ discharge pasaa~e 14~ is f c~rm~d in th-drive ~h~ft 1:18 in this embod~ment, the outer ~nds of t~e axis borea lO~A and 102~ cornmunica~ce with the d~ ~h~xg- ahambor~
under high pre~suxe, and ~he inn~r ends thereof oomntur~ ' o~tc~
Wit~l tl~s c~ank c~e iO4 undQ~r lcw ~ress.~rQ, ~rh~ rank c~

. .

2Q7 i~ ~

lQ4 and th~ discharge ~hambers 111 and 112 are sepu~ated in a fluid tight manne~, by th~ soal~ 141. 'rhe ~el~riqe~nt: i9 thu~ p~eventod from l~aking intc> the cJran~c c~oe 104 ~ro~ eo~h di~ohaa-g~- oha3nb~r.

In p~rticul~r, each Of the 8eal~ 141 ha~ a U-shap~d cross ~e~ti~n with two substantially parallel ~dges which are forc~
ln cl~se contact with the inner wall~ of the axial b~re~ lOlA
and lO~A and the outer sur~ace of the d~iv~ ~haft ~18 un~er 1~ the pr~s6ure in the dl~chaxge chamb~rs. The applied pxe-~sure to the ~al 141 for causi~g it ti~htly to contact the a~oc~ted a~ial bore and the drive ~haft 118 increase~
proportionally to the pres~ure in the corresponding di~h~rge chambe~. There~o~e, the ~eal6 141 provide an ~ffect~e seal.

The compressor of the pre~ent emb~diment u~es the interior o~

the drive ~haft a~ the di6charge passage~ 80 that thG
dis~harge pa5~ge can be formed at a po~ition whe~ it does not in~erfere with the bore6, without increa~ing the outer diameter of the compres~or. This feature r~nder6 the ~ompres~or light~ and ~ore co~pact, while maintaining a predet~.rmined co~pr~inq capa~ity.

Fig. 4 illu~trate~ a ~odifiaation to the ~eal. The modi~iod ~al 142 has a gene~al~y rectangular or ~quaro or~ oction~
and is fitted ove~ the drive shaft 118. The pre~e~re in tho discharc~e chamber~ 111 and 112 acts on tho outor ~ur~c~o ~nd ~ 0 7 ~ 8 ~uter ~nd faces of the seals 1~2, ~or c:ausing the seal~ 142 to be fo~ed aga~n~t tho innor ~3nd6 o~ th- axial ~orfiG lOlA
and lG2;~.

Fig. 5 illu~tra~e~ another modification to the ~eal. The mo~ifi~.d ~s~al 1~3 ha~ a g~n~rally trlangular croas section, and is ~ltted over t.h~ drive ~haft 118. The pr~s~ur~ in the di~chaIge cham~or~ 1l1 a~d 112 act on ~h~ irlclined. ~urf~cas of the ~als 143, for pre~ing the inner ~urface~ and inner end face~ of th~ seal3 143, re~pectiv~ly, against the outer 3urface o~ the drive sb~t 118 and the inner end~ of the axial bore6 lOlA and 102A. Both ~nodification~ prevent th~
refrigerante~ from leaking ~rom the discharge chamber~ 111 and 112 to the crank case 104.
Ref~rring now to Fi~s. 6 to ~, the ~econd embodisnent of the pre~ent invention will now be de~cx~b~d. Ae ~hown in Fig. 7, the discharge ports lOSb and 106b are equldi~tontly ~rranged around the discharge pa~sage 140, within imaginary circl~c passing the c~ntexs of t~e bore6 lOla and 102a (only th~ reax 6ide iB ~hown ) . ~he roax di6ch~rg~e port~ 106b are therefore arranged at equal dist~nce~ fxom th~3 di~char~ae ~ort 128.

Pa~sages 160 BUpply a ~ ty lubricant in tho crank ca~e 104 to the radial bea~ing~ 114 and 115, ~nd ar- fc~ d in the cylinder block~ 101 and 102. ~ip typ~ ~al~ 161 ar~ di~pooed between the drive ~h~ft 118 and the Va~lVQ plat~ l OS and 106~

2~7~t.ifl~
--~4--in ord~r to prevent the refrigerant fr~m leaking tb the discharg~ cham~r f~o3n th~ ~p~ b~tw~en ~h~ dr~ hAf~ 1 la and tho vdlYe pl~tel3 105 ~n~ 106. E~h o~ the llp ~ypc ~ea,le~
161 h~n ~ gcner~lly conic~l or :~kirt-like sk~pe~ ~ith the~ir ~mall diametar porti;)n~ held between the dr.ive ~haft 118 and the valve plates 10~ and 106, and ehe larger diam~ter portlon~
abuttlng ay~inst the outer surface of th~ radlal bearings 114 and 115.

In this embodiment, as in ~he fir~t e~bodiment, the seals 161 separate the di~charge chamber~ nd 112 and the crank casQ
104. The ~efrigerant i6 therefore prevented from leaking to the crank caAe 104 from each discharge chanber.

~n addition, ~ince th~ individu~l front di~charg~ port~ lOSb are arra~ged equidi6tantly fro~ the di~charg~ pa~sage 140, the refrig~r~nt gas discharged from the discharge port~ 105b smoothly flow~ into th~ through h~le6 140a. As th~ openin~
o~ the disc~arge pa8~age 140 faces the diech~rge port 1~8, the re~rigera~t gas is dischaxged smoothly $rom th~ di~charge port 128 to an ext~rnal refrlg-rant ga~ pipo.

The reaL di~chaxge ports 106b are e~uidistantly di~osed from the di~charge port 128, such th~t the refrigeran~ ga~
discharg~ from each dischar~e ~ort 106~ al~o flows ~m~thly ~oward the dischar~e ~ort 128.

`~ O 7 ~ 8 ~15- `
Fiq. 9 illu~trate~ a Gc~nventiona~, comp~:essor having a plur~lity of dieohargo porte 152 which oonneat a di~h~rg~
ch~mbcr 150 to compreJ~ion ch~mber~l (boreo~ 151~ And whi~ ;re clrr~ng_d on the a~mc ~ircu~n$crcnc~ ~round ~ e bhGft 1;3.
~hen the discharge chamber 150 is arranged inward of a ~uction chamber 154, ~art o~ the ~ischarge cha~ber 150 pro~ects near t~ outex periphery of a housing 155, ~nd communicata~ at that projecting ~ortion, with ~ discharge p~s6age 156 foxmed in ~he cylinder block3.
n the conventional ~ompres~or, there~ore, the individual . discharge port~ i~2 are not e~uidi~tant fro~ the di~charge p~age 156. The refrlgerant di~charged into the di~charge chamb~r 150 doe~ n~t flow smoothly toward tho discharge pa~sage 156, which C~S~8 inevitable po~er Lo~s due to the di~chaxge resistance. Meanwhile, when the diacharge cha~ber i~ arranged outward o~ the ~uction chambe~, ~uch power lo~
wa~ like~ e in~vit4ble. To reduce the power ~o~ due to the di~ch~rge resL~ance, it is con~idered nece~sary to enlarge tlle diameter o~ the discharge pass~ge in the conventionai æwa6h plate type compresRor; a minimum of ~ mm i~ s~cur~d fox that diamater. ~hi~ wlll increA~e the ov~xall ~ize of the aompre3sor .

Ac:corcling to the ~resent embc~diment, th- r~frigerant discharged to t;h~ fro~t and r~ar di~eharg~ ~hamb~r~ 111 ar~d 112 smoothly flows toward the di~char~e ~ort 128, a~ d~scrlbed 2 ~ 7 ~ L~ 8 ~bcve. This s~lppre33e~ the discharging re~i~tance, and lowers th~ pow~r los~. with the minimum diameter of t~e di~ch~rge port o~ th~.c~nvention~l compro~or set eq~al to the di~m~t~r of the di~chA~ge p~ ge 140 of the c~mpre~sor of ~his embodi~ent, the conventional compre660r and the comprea~or of this ~mbodi~ent were opexated under the ~ame operation condition~, ~uch as the di~harging pres~uxe, ~u~tion pr~ure and th~ nl~ber of rotation~ The result is ~hat the compr~or of the pre~nt embodiment ha6 a lower power lofis th~n tl~e convention~l compre~30r by about two percent to 3 percen~.

Fu~theI~ore, the conventional compre6sor reguire~ that the cro~ ectlonal area of the di~charg~ pa~ag~ bo increa~ed to suppre~6 the di~charging reoei6ta~e. ~educing that cross-sectional are3 increase~ the di6charge re6~tance, and lowor~
the volu~e efficioncy of the oompxe3~0r, i.e. the theoretical ratio of t~e discharge volume of the refrigerant to the actual volu~e discharged. With the di~charge pa~age 140 formed in the drivQ shaft 11~ and ~he di~charge port~ 105b and 106b arranged e~uidi~t~nt fxo~ the di~charge ~a3sage i40 a~ in thi~
ombo~i~ent, howo~r, it w~s proven that tbe volume effi~ioncy does hot drop 6ignifioan_1y, even if the diameter of t~n df scharg~ passag~ 140 or the cro~ estion~1 area th~reof i6 reduced.

~or instance, u~der th~ operAtion c~nditiona of the 2 0 7 e~ 8 discharging pxe~sllre Pd t 15 kgJcm2, the ~uction pre6~ure Ps e 2 kg/cm~, and the num~er of rotatione~ of 1000 rpm, the volume efficiency ~1~a5 measu~ed fc~r different crc~ss-~ectic~nal are~s of th~ dlschar~e pa~sage 140. Flg. 8 exempllfles the result~... It i8 apparent from Fig. 8 that the volum~
efficiency hardly drops ev~n if the diameter o~ the di~char~e p~æaag~ 140 i.s set to 3 mm (cro~ 3ectional araa of 7 mn~
maintalning ~he 3e~rel ta about 70~.

with the discharge pa~s~ge 140 formed in the drive shaft 118, if the cr~6s ~ecticnal area need~ to be increa~e~, ~he diame~e- of the drive ~haft 118 ~hould ba insrea~ed accordi.ngly, to secure ~he mechanicAl strength of the dxi~re ~hat 118. Thi~ increaso~ the ~ize of the compree~or. A~ tha volume e~ficiency doe~ not ~ecrea~e substantially, even with a sma].ler diameter of the di~charge pa~ge in this e~bodiment, the ~echanical ~t~ength cf the drive ~haft 118 can be m~intaine~ with~t making it thicker. ~he vresent emhodiment will ther~fore not in~rea3e the 8ize oi tha compre~or.

In seneral~ a swash ~l~te typ~ c~nproeeor aauQO~ a di~ch~ge ul~;ation in accordance wi~h th~ n~ r of cyllnder~, and vihxation ~nd noi6e oc~ur accord~ngly. Con~entionally, a 2S muffler i~ prc~idod for th~ di~ch~rged refrigerhnt g~s, in order to reduco t~4 di~:ohaxg~ p~ Qtie~n. With the ~iEichar~3e 18 2 ~ 7 ~
pas~a~e 1~0 p~ovided in the dri~ shaft 118 a~ in this em~odiment, how~ver, the refrigerant ~a~ di~ha~g~d to th~
di~axgQ chAmbt~ 111 from the front bor6~ lOlz~ i~ di~char~ed f:co~n th~ di~:ohargt~ poxt 128 through the di~ah~rqe p~ Qge 140 S and the rear discharge ch~nber 112. At the t~me the refri~er~nt 1~ di:~chA~g~d from the discharge pae;s~e 140 to ~che discha-ge ch~er 112, th~t re~rigerant i~ expanded in the di~cha~ge cham~er 112, to ~ield a gre~ter ~uffler effect, thus reducing tne discharge pulsation.
1~
The p-esent e~bodi~ent th~r~fore doe~ not need to have a ~ep~rate mu~ler to prevent discha~ged pul~atia~ of the refrigerant on the front 6ide. ~he muffler to be ~ttAched to the compreseo~ ~ufficeQ to minimize or prevent the discharge ~ulsation of the re~rigerant on the re~r side, thu~ makin~ it ~06si~1e to reduce the ~i2e of the compre3s~r. In thi~ c~6e, it might be de6ira~1e to reduce the cro~s s~ctional dimension of the pa6sage 140. For in~tance, when t~.e capacity of the compres~,or is 150 cc, the diameter of the pas6age ~4~ could be 5 mm or le~s.

The dis.charge port 128 of the pres~nt embodiment ~ay b~
replacad w~th another dischargo port that iB ~hifte~ sidewar~s ~rom th~ central axis of the discharge pas~age 140. In ~hi6 cas~, tbe smooth flow of -he refrig~rant on the front 6id~ ~an be se~ured.

2 ~ 7 ~

thi~d e~;vodi~ent o~ the present invention will now be de~xi~od ~i~h reFerence to Figs. lo throug~ 2~.

A~ s~wn ln F 9. 1~ ~ the rront an~ rear cyllnder blocRs 1 and 2 are coupled t.ogethe~ by ~olts 70~ A driv~ shaft 3 i~
rotatably fitted in the cylinder bl~cks 1 and 2, ~i~ radial beaxings 4 and 5. A ~wash plate 6 i~ fixed to the drive 6haft 3. The cylinder blocks 1 and 2 define a cran~ ca~e 7. Thl-ust ~aring3 ~ and 9 are ~i~posed betw~en 'he ~wash plate 6 ~nd the end faces of ~he i.ndividual cylinde~ blG~ks 1 and 2. The cylindex blo~ks 1 and 2 are x~eapectively provided with xef~igerant inlet por~s 10 and 11 to which refrigerant ga~
pipeR ( not snown ~ a~e cor.nected.

A~ shown in Figs. 11 to 16, a plurality ~ oyiinder~ 12 ar~
equidistantly formed in tke cylindex bloc~ 1 ar~und the drive ~haft ~, and a plur~lity of cylinder~ 13 are ~imilarl~ formed in the cyli~der block 2. A~ she~n in Fig. 10, a two-head pi~on 1l is retained in ~ recipro~ative ~ann~r in ea~h p~ir of ~on.t and rear cylinder~ 12 and 13. Semis~heric~l s~.oe~
15 and 16 are di~posed be~ween the pi~ton ~4 and tha ~waeh plat~ 6. A~; the swash plate 6 ~ot~s, tho pieton 14 recl~r;~cates ~orward a~ld ~ac~cward ~ the sE~30ciat6~d cylinda~
12 and .13.

The ~h~s 15 and 16 a~ r~pocti~r~ly fittcd ir. the rc.,esse~
59 and 60 of th~ pistor~ 14. ~ p~r of ~uotion ch~_r~l 2S ~r~d 2 ~ 8 2.6 are ~efined in ~ach pi~ton 14. ~he recesses 59 and 60 co~ nicAt- with tho euotior~ ¢hamb~3r~ 2 5 dnd 26 through c~il E~ gc~ 61 ~Ind 62. Plart of the sphrarico.l port~c~n oi e~::h ~hoe 15 ~nd 16 i5 fl~t, ~nd ~he gaps ~or oil sumEI~) dafir~ed between the~e f lat ~urface~ and the reces~&s 59 and 60 always co~ nicate wlth the oll pa8sage6 ~l and 62, respective~y-A ~ont cover 17 is securely fa~tened to the outer end ;:~f the cylinder~ block 1 by bolts 71. $.ikewi$e, a rear co~er 1~ i~
securely fa~tened to the o~ter end of the ~:ylinder block 2 by bolt~ '72. In both cover~ 17 and 18 are formed di-~charge chamber~ 19 and 20, which ~re connected t~ thè cylinders 1 and 13, ~ia dic-c~.arge port~ 21 and 22 on the covers 17 and 18.
The disch~rge chasnb~r 1~ communicates with an ~xtexnal refrigerant gas pip~ ~not ~ho~n) via a discharge p~8~age 23.

A lip type seal 2~ i6 ~rovided on the front outer surface of the drive shaft 3 to prevent the refrigerant gas from lealsing out~ide the co~re~sor ~rom the discharg0 c~l~nber 19. ~he ~uction cha~ ers 2S anà 26 c~rnnunicate with the c~ank c~8e 7 via inlet~ 27 and 28 ~ormed in each ~iston 14~ Th~
refrigeraslt gas in the crank C:a.8~ 7 can tber~sfore flGw through the~ inlets 2~ and 28 into the ~uotion cham~ers 25 and ~6, re ~pect ive ly .
P~s ~hown in ~ig~. 10, 15 and 1~, the ~wash pl~t~ 6 ie E~ro~idQd with a plurality c,f t~a6~age~ 49 which ar~ formod horiec~ntAlly 207~ 18 -2l-within th~ ~wa~h plate ~. ~he pa~6age~ 4~ are arranged at prede~er~in~ distan~eo ~ro~nd th~ ~ri~o Ghat 3. The pa~6agG~ 49 facing ~he lnlet po~ 27 And 2~ ~er~e te ~moothly g~ide the ~efr~ger~nt g~ in thc cr~nk c~se 7.

A suctlon por~ 3~ 1~ rorm~d through a ~ront head and 2~ of e~ch plston 14. A suction v~lve 31 1~ att~hed to the suctlGn port 30. ~s shown in Fig~. 17 and 19, the suction valvc 31 in~lu~e6 a valva seat 32 securely fitt~d in the fronl: head end 29, a disk-shaped float valve 33 retaina~ the valve scat 32~ and a retainer 34 ~Fig. 19) for retaining and holding the flc~at val~7e 33 in the ~Jalve ~eat 32. ~he valve ~at 32 ha~
a pair o~ epenings formed therein as shown ir. Fi~. 18. Each opening 35 i6 opaned and clo~ed by tne fleat valve 3:~. A hole 1~ 36 is form~d in the central portion of the float valve 33.
'~ith the opzning~ 35 clo~ed by the fl~at valve 33, the hole 3~ is closed by a bri;lgin~ ~ortion 37 located between th~
opening~ 3 5 .

A ~uction port 39 i6 formed throug~l a rear head ond ~g of each piston 14. A sucti~n ~alve 40 ~imilar to the- sl~ction valve 31 i~ attached to t~,~ suction p~rt 33. A di~charge valv~ ~1 is att~ch~d to the di~charge port 21~ As shown in Fi~. 17, the ~isch~rge valv~ 41 àncludes a val~re ~eat ~2 ~3ecuro~y fitted in the front over 17, a ~i~k-~hapad float ralv~ 43 retainocl in the valve seat 42, ~nd a retaines ~ f~r ro~aining ~nd holding th~ f loat v~lve 43 in the ~alv~ t 4~. ~he .

2 ~ 7 ~ 8 valve ~eat ~, rlG~ valve 43 and retainer 44 hav~ the same ~hapes ~ he val~ro ~t ~2, floa~ valv~ ~3 and r~tain~r 34 of th~ 6uctl~n valve 31.

A discharge valve 45 simil~r to the dioch~rq~ valv-e 41 i~
at.tached to the dl~c~arge port 22. At the tLme the he~d and 29 of each pl~ton 14 make~ a baokward ~ove~ent ~when the pi~ton 14 mov~s t~ward the ~ear ~ide~, the refrig~-a~t gas ln th~ su~tion cl;amb~r 25 pu~heo b~ck the float valve 33, t~ open th~ epening6 35~ 9o that the gas is drawn into the compre~ion ~hambe~ 46, between the head end 29 a~d the fron~ cover 17~
The movem~nt o the flo~t valve 33 18 re~tri~ted by ite po~.ition aqain~t the retainer 34. At tke timc the head end 29 of the pi~ton 1~ make~ ~ forward mo~ement ~wh~n the pi~ton 14 move~ towa~d the ~ront side), the refrigffrant gas in the compreas~on ch~mber 46 pushe~ back the float valve 43 to open ~he open ngs of the val~e ~at 42, 90 ~hat the gas iB
di~ch~rged into the discharge chambe~ 19. ~he movement o~ the ~loat valve 43 ie re~tricted by it~ poa tion again~t the retainer 4~.

The suction and discharge of the re~rigerant are 3i~ilarly carri~d eut, via a ~uctio~ val~e 40 ~nd a dischargQ val~e 45, with re:~pect to a co~pr~s6ion ch~mber 48 defined bet~een the ~5 oth~r he~d ~nd 3~ of the piston 14 and th~ rear cover 18.

The drive shaft 3 ha~ one en~ pr~ruding outwa~d from th~

~ . . .
.

2 ~ 7 ~ !~ 8 fr~nt cevex 17, and the c>thor end projec:ting into the discharsJe c:hamber 20 on the rear c~vor sid~. A discharg~
pas:cag~ 5t~ ormod in th~ axial oer~tral port~n of th~ driv~a ~:h~ft 3, ~nd ic open to the di(3aharge oham~er 2~. ~ plu~o.lity of ontlets 51 extend radially, are forme~ in part of the drlve ~h~ft 3, ~nd c~e l~at~d in the dl3charge chamb~3L lg on the ~ont cove~ side. The outle~t~ 51 allow ~he discharge cha~nb~r 19 to co~runun~c~te with ~he discha~ge passage 50.

The radial 3~earing6 4 and 5 ale retained in annular rece6se~
52 and 53 o the respective oylinder block6 1 and 2. Oil passage~ 54 and 55 ~upply a lubricant to the ràdial bearings 4 a~d ~, and are formed in those porti~n~ of the drive shaft 3 wh1~h are loc~ted in th~ rece~-s 52 and 53. A plurality of ring-6haped ~eal~ 56 and 57 are retained in th~ re~pective recesses 52 and 53 inwardl~ of the a~ociated radial hearin~s 4 and 5. The -Real6 S6 and 57 ~ealingly separate the crank case 7 f~om th- ~ischarge cha~ber~ 19 and 20.

~ wing 58 i8 6ecurely ixed to the discharge pa~eagR 50. A~
6hown in Figs. 10 through 1~, when the drive ~hA~t ~ ~o~at-o in the direction of the arrow ~, the wing 5~ forcef; air to f low in the dixcction of the arrow ~.

~5 The re~rig~rant ga~ iB led ir~tc~ the crank cA~e 7 fron~ thQ
external ~efrigeran~ ga6 Pi~e, and th~ refrig~arant g~ in. th~
crank caoe ' enters the ~uotion chan~bers 25 ~nd 26 via th~

. , . . ~ .

2~7~ s8 .~
inlet ~)orts 2~ and 28. ~be x~frigerant gases in the suction cha~bers 25 and 26 ~re drawn ~nto the co~pr~8~ior. chambGre 46 an~ 48, ~ia the suction p~rt~ 30 and 3~, a~d pu~h b~ok the float valve~ ~3 ~nd g3, in acc~rd~nce with the mo~ement o~ the pistons 14. The refrigerant gases in the co~pr~sion chamber~
46 and 48 ~re di~charged into the dlschar~a chambers 1~ and 20 via the dlschar~e por~ 21 and 22t and pu~h back the float valve 43~ ln acaordance with the moYoment of the pistons 14.
The refri~erant ga6 in the di6ch.arge ch~mber ~0 enter6 the ~i~cha~ge pa~sage 50 throug~ an opening 65.

The refrigerant g~6 ha~ving entered the discharge pag~age 50 from the discharge cha~ber 20, f low6 out to the di3charge chamber 19 fro~ the outlet~ 51 by th~ action of the wing 58.
Ths refrigerant gas in the dischar~e chamber 19 is discharged, ~la the diacha~ge pas~a~e 23, t~ the external refri~erant ga~
p~

Conventionally, a si~gle ~uction pa3~age i~ pro~ided ~etween each pa~r of adjoininq cylinders in eaoh c~linder block. Such suction pas~ag~s co~ld reduce the str~ngth Or the aylin~er block. Fux~her, the diEcharge pa~saqe is alao ~rovided in ~h~
cylinder block. ~he di~tance betwoen the cyl.in~er~ i.s th~ref~re increased such that the requixed strer.gth of the cylinder ~lock can be secured. ~ long ~R the ~uction and dischar~e pa~agea are ~regent in the ~!~lindo~ block, the di~anae b~tweQn the cYlinder~ oann~t b~ optimiz~d.

-25- 2 ~ 7 ~ 8 In th~ pre6ent embodiment, th~ r~frig~rant ga~ is drawn into the cranlc c~e 7, and i~ led into the co~pro~9ion cha~nb~rs 46 ~rlæ 48, vii~ th~ uotion ohamb~sr~ 25 ar~d 26 in th~ piuto~ 14.
unli~c con~ention~l compre~or~ the prc~ent cc;mp~ or doc~
not require a plu~Ality of ~3uc:tion passages in the cylinder bl.o~k. In the pre#ent emboc~lmenl:~ t~ efrigerant gas is di~chaxged ln~v the di~char~e ~han~e~ 20, and flow6 to the di6cllarge passag~ 23, vi~ the diwharge pae~age 50 $n the drive shaft 3. It elimina~es the need for ~he discharge lo pass~ge in the cylinder block, which i~ needed in the conventional ~wa~h plate type compressor. The eliminati~n of the suction pa~Rages and di~charge pa~agQ from the cylinder block~ i ~nd 2 permits ~he cylinder~ 12 and 13 to be aIranged closer to one another. The clo6er 3epar~tion between the cylind~ 12 and 13 re~ults in a overall reduc~on in th~
diameter of ~ach cylinder blo~k l or 2. It i~ now pos~ible to make th~ overa}l cornpressor ~maller and ~ighter.

Unlike convQntional c~mpre~ors where ~uction cham~ers are provided in ~he front and rear cylinder blo~k~, the ~uctio~
chalr~ers of ~he pra~ent embodiment ~xe provided within e~ch pis~o~ 14. ~hi~ ln~entive impIoveme~t fur~her contributes to the ov~rall downsizing of the compre~or.

The refrigerant qa~ in the co~ression chamber~ 4~ ~n~ 48 i~
~i~char~ed when the pre6~ur~ becomes gxeatar than the pros~ure of the refrigerant ~as in the di~cha~ge cha~er~ 19 and 20.

2 Q 7 ~

A~ t~e dischar~ chamber 19 i~ clo~ed to the di~charge p~a~e 23, it~ pr~8~1re will not ri6~ too hi~h. Si nce the dieoh~rge~
chsmbor 20 i~ loa~lted ~cm~tcly ~rom the o~tlet:~ 51r ho~ever~
tho pre~ re in ~he ~di~ch~rge chamb~L :20 ~lepend~ on the di~chaxge resistance between the di6ch~rge chamber 20 ~nd the ou~lets 51.

~o pr~ent ~he pre~6~l~e ~ n the ~i~charg~ aham~er 20 ~rom rising toc~ high, it would be advisab1e to pro~uce force to dr~w ~n the re~r.igerant ga~ at the opening ~5 of ~he! di~ ha:rge passa~e S0. 'rhis ~orce i6 cau~ed by causing the refLigerant gas to flow against the di~charge resiQtance of the d~scharge pa66age l~iny fro~ the discharge chamber 20 to the outlet6 51.
In this embodiment, the wing 5~ ~ends the refri~rant ga~ in the dis2harge pa6~ge 50 toward the~ ou~1~t~ Sl.

Since the wing ~8 is ~mall, it Rlight1y incr~as~; th~
rot~ticna1 resistance of the drive ~haft 3. 'rhe pres6ure in the di~c:har~e chamber 20 ~an thereforo be reduced wi thout causing any si~nificant power lo~. The roduction o~ the pressure in the di~chaxge chan~ber ~0 ~llow~ tlle refrig~rRnt gas in the compre~sion chamber 48 to b~ di~ harqed ~o t~
discharge ohamber 20 withou~ being overcompre~Jed. It~ ~
ther~fore possib1e to f3uppref~ the disoh~rqo pu1s~tion and pow~r loss originatin~ f rom the c,v~rc~ompr~ssion of tho ~efrigerant gas. AE~ the rotational ~n~d ~ thc~ compra~or in~rease~, the volwne o~ ~he circulat;ng r~frig4rar~t g~

2 l~ 7 ) .~

incroa~e~ ~o that the overcompreBeivn ~n~ di~cha~ge pul6ation be~me s greater in p~oportion t~ th~ rot~ nal ~p--d . ~h~
di~oharg~ a~ei~t~ng a~tio~ of ~he wing 5~ ouppr~e~ the ~v~r~mpre~ion in the comp~o:s:sion ch~mbe~; 48~ thu~i S ~upp~e~ing the power loss and di~charge pulsation at the time ~h~ co~pIe6sor ~ns at a hi~h ~ed.

~hen t~e p~esfi~re o~ th~ reIrig~rant ga~ ~n th~ co~pr~ssion cham~r~ 46 ~nd 48 fall ~elow those in ~he s~ction cha~be~s 25 and 2~, the re~r1gerant gas in the suction ~h~mbers 25 and 26 is 6uc~.ed into the ~mpxe~sion ~h~mbers 45 ~nd 48~ ~he flow resita~ce in the refrigerant ga~ pa~ge~ oxtending from the crank oase 7 tc the comp~e~ion cha~b~ 46 and 48, i.e., the suction xe~i~tance of the refrigerant gaa, affects the pres~ures in ~he 3UCtiOIl chamber6 2~ and 26. The highex the ~ue~ion regiBtanCe is~ th~ l~rgex ~he Duction pulsat~on and power 109g.

The foregoing suction re~i~t~nce mainl~ d~pende on the ~uction re6i~tances at the suction port~ 30 and 39 in the limited region~, na~ely, on the he~d ~nd~ 2Y ~n~ 38 of the ~i8~0n 14.
~h~ suctio~ rssistance~ at the suction ports 30 and 39 ~n ~-re~uced by increasing the cross-~ectior,al a~eae o~ the ~u~tion valves 31 and 40. ~he float valve 33, whioh includeD the ~5 suction valv~ 3~ ~r 40, make~ almo8t a par~ll - l movo~nt between th~ valve ~2at 3~ and ~he retainer 34. Civon thAt tho par~llel displacement of the float v~lve 3~ i9 y, as ~hown in 2~7'i.~8 Fi~. 17, ar~d ~he imler circumierential length thereof is ~, the re Erigerant-pa~in~ cro~a-~ctional ar~a ~f th~ 6uo~ion ~,ralve 31 or 40 io expre~60d by re.

Tha ~uction val~te in th~ conventional c:ompre~c r ~ 8 an o~rerhang type valve plat~ 6C~ that derlection o$ the valve plate vp~n~ tha suction poxt . The oros~-~ectiona1 are~ o~
6U-tl suc:tion val-re i8 approximately one half that o~ the 6uction val~.~e 31 or 40 ~n the pr~se~t ei~lbodlment, if the alnount of deflection o~ the valve plat,e i~ equal to the parallel displs.~oment of th~ fl~at valve 33.

An in~rezlse in the amount of deform~tion of the valve plate increA~e~ the suction valve cross-~ectional area. I~ ~uoh v~lve pla'ce is ussed on the head end 29 or 38, it cau6es the ~ize of the pi~ton 14 to increase. ~ven if the displacement of the f loat valve 33 is 6et le6:~ than the ~mount of deflection of the valv~ plate, the cxo~-sectional ~rea of the suction valve 31 o~ 4G becomes greater than that of t}le c:on~Tentiona~ 6~lction valve ~ thus permitting the suction resistanoe to be 6uppre~qed without incr~asing the 2ize of th~
pi ~ton 14 .

Each of th~ dis~harge valve~ 41 And 45, which ir.cludes the f loat ~Jal~re 43 thorein, would inorea~e th~ ~ro~6-d~ coha~e port~ 21 and 22, or would redu.c~ the diE:ch~rg-s s~cictanc~
without increasi~g the thickn~o~es o~ the cov~ra 17 and ~8 2 ~ l 8 ~herefc>re, ~he di6chAxge val~es ~1 and ~5, tog~th~r with ~he wi~g 58 contribute to the redu~ti~n o~ the dieohargo Pulsatio~ and power lo~

As a misty lubricant i~ ~ixcd to the refrigerant gas, ~he lubrio~nt will ~ick on th~ w~ll of the ~lsch~r~e passage 5~.
PArt o~ the lubricant ~n t.he wall o~ the discharge pas~age 50 ~nterA the r~c~se~ ~2 ~nd 53 ~rom the oil pa~age~ 54 ~nd 55 by the centrifugal force created by the rotation of th2 driv~
~haft 3, ~or ens~ring ~ ~mooth lubrication of the radial bearings 4 and 5.

The ~izty lubricant in the r~fri~erant will stick on the walls of the suction chambers 25 and ~6 in ~h.e pi~ton 14. ~he lubrican~ enter6 the gaps 63 and 64 rom the oil p~age~ ~;
~n~ 62 due to the reciprocation of the piston 14. ~he sliding po~tion~ between the recQsses 59 and 60 and the ~hoes lS and 6 are lubricated, for preventing ~he ~lidinq portion6 from ~eing b~rnt. Although the gap~ 63 and 64 8er~e as oil well~
the lu~:ricatic,n between the sh~e-~ 15 and 16 And the reces~e~
59 ~nd 60 co~ld occur without the ~aps ~3 and 64.

Tho rec~ss 52 i8 connected to the di3charge oha~ber 19 a]on~
the out~r surface of the dxive 6haft 3, and the recess 53 to ~he disch~rge cha~ber 20 along ~he outer ~urf~oe of th~ dYive shaft 3. I~herefor~, there is some c~n~rn th~t th~
refrige~ant ~ might leak to the cr~nk aase 7 along the out~r ~073~18 -3~-su~fa~e of the ~riv~ ~haft 3. However, the s~als 56 and S7 are provided ]~etwe~n ths crank ca~ 7 and the r~c~ e 52 and 53, and oome into c~oco contaot w.ith the outer eurf aoe of the drive ~3haft 3 and the inne.r w~ th~ reces~ 52 ~nd 53, under pressure ~rom the rerigerant gas. This design oan tbus prevent the discharged refrig~rant ga~ from leaklng to the crank case 7 along the outer sur~ace of the driv~ ~haf~ 3~

The present in~ention i~ not limited to the above-desarib~d embodiments, but the ~tructUre m~y be modified as ~hown in Fig. 20.

In thi~ mo~if~cation, an o~tlet 66 i~ f~rmed in the rear cover 18, fAcing the ~pening 6~ of the drive ~h~ft 3. An external lS r~frigerant ga~ ~ip~ (not sho~n) i8 connec~ed to the outlet 66. Inlet ports 67 are formed in that portion of the drive ~ha~t 3 which is loc~ed in the di6~harge ch~mber lg. The inlet port6 67 permit the discharge chamber l9 to co~municatc with th~ dlscharge pa ~age 50. A wing 68 is ~ecurely fitted in the di~charge pa~sa~e SC. ~ the drive sh~f~ 3 rotate6 in the dir~tion of an arrow ~, the wing 68 feed~ ~ir in the dixecti~n of an arrow ~, a~ shown in Fig. 20.

The ref~.lgerant gas in th~ compre66ion ~hErbors 4~ and 48 i8 di~charged t~ the dis~h~rg~ chamber# l9 ~nd 20 fr~n the discharcle por~s 21 and 22, in accordance with th~ movemon~ o the pi~ton 14. The refrigeran* ga~ di~ch~rgod to th~

~ ~ 7 ~ 8 discharge ~ha~nber 1~ en1:er~ ~h~ di~charge pas~ag~ 50 fr~m the:
inlet pc~ts 67. Th~ rlafrig~ra~t g~; dir~ch~rg~d t:o ' h~
di~haxg~ c~ha.~b~r 20 from th~3 di~ahaL-g~ port 2~ i~ di~oh4~ged di~eotly ~om the ou~lct por~ 66 .

Due to th~ long di~t~rlce betwê!en the di~charge chamber 19 and the oul:let por~ ~ t th~ dlscharc~e resi . tance there~e~ween affect~ the pxessu~-e in t~le div~chaxge chamber 19. To px~vent the pres6ure in the discharge chan~.ber~ lg and 2~ from risin~
too high, it wc~uld be desirable is ~.o produce a suc~ion ac'cion ~t th~ inlet ports 67, With a 6uc~ion ~orc~ froln th~ disch~rge chamber 20 to the outlet port 66. ~hs ~ucking ~orce i3 caused by cau~incJ the r~fri~erant. ga6 to ~low against ~he dlsc~a;rge resid~ance of the passage lying from the di6chaxge chamber 19 ~o the outlet port 66. In this em~od-men~, the wing 58 forces thQ re~-igerant gas in the ~i~ch~rg~ pa~sage 50 ~owa~d the outlet ~ort 66.

Claims (18)

1. In a swash plate type compressor having a crank case, a cylinder block, a plurality of discharge chambers, a rotatable drive shaft partly disposed within said cylinder block, a swash plate mounted on said drive shaft and rotatably disposed within the crank case, and a plurality of pistons drivably coupled to the swash plate, and housed within said cylinder block, for cyclically compressing a refrigerant and causing it to be discharged, the improvement comprising:
said drive shaft having a central geometric axis, and including a passage formed along said axis, for causing the refrigerant to communicate between the discharge chambers: and seal members, disposed between the cylinder blocks and the drive shaft, for sealing a gap between the discharge chambers and the crank case.

2. The swash plate type compressor according to claim 1, further including a plurality of bearings for supporting said drive shaft, and a plurality of recesses for retaining said seal members.

3. The swash plate type compressor according to claim 2, wherein said recesses include innermost sections, and wherein said seal members are retained at said innermost sections, and said bearings are retained closely thereto.

4. The swash plate type compressor according to claim 2, wherein said recesses include innermost sections, and wherein said bearings are retained at said innermost sections in said recesses, and said seal members are retained closely thereto.

5. The swash plate type compressor according to claim 1, wherein each of said members has a ring-shape and a generally U-shape cross section, such that the opens ends of said U-shape seal members face said discharge chambers.

6. The swash plate type compressor according to claim 1, further including a plurality of cylinder bores, and a plurality of discharge ports for connecting said cylinder bores to the discharge chambers, and wherein said discharge ports are equidistantly arranged with respect to said passage.

7. In a swash plate type compressor having a crank case, a cylinder block, a plurality of discharge chambers, a rotatable drive shaft partly disposed within said cylinder block, a swash plate mounted on said drive shaft and rotatably disposed within the crank case, and a plurality of pistons drivably coupled to the swash plate, and housed within said cylinder block, for cyclically compressing a refrigerant and causing it to be discharged, the improvement comprising:
said drive shaft having a central geometric axis, and including a passage formed along said axis for causing the refrigerant to communicate between the discharge chambers, a plurality of discharge ports equidistantly arranged from said passage.

8. In a swash plate type compressor having a crank case, a cylinder block, a plurality of discharge chambers, a rotatable drive shaft partly disposed within said cylinder block, a swash plate mounted on said drive shaft and rotatably disposed within the crank case, and a plurality of pistons drivably coupled to the swash plate, and housed within said cylinder block, for cyclically compressing a refrigerant and causing it to be discharged, the improvement comprising:
a plurality of pistons movable within corresponding bores, a pair of suction chambers provided in each one of said pistons, and communicating with the crank case; and a suction port, provided in each of said pistons, for connecting each one of said suction chambers to each one of said bores.

9. The swash plate type compressor according to claim 8, wherein each of said suction ports has a suction valve for opening and closing said suction port.

10. The swash plate type compressor according to claim 8, wherein each of said discharge ports has a discharge valve for opening and closing said discharge port.

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11. The swash plate type compressor according to claim 9, wherein said suction valve opens said suction port when said associated piston sucks the refrigerant, and closes said suction port when said associated piston discharges the refrigerant.

12. The swash plate type compressor according to claim 10, wherein said discharge valve closes said discharge port when said associated piston sucks the refrigerant, and opens said discharge port when said associated piston discharges the refrigerant.

13. The swash plate type compressor according to claim 8, further comprising a wing disposed along a refrigerant passage fo for forcibly feeding the refrigerant when said drive shaft rotates.

14. The swash plate type compressor according to claim 8, further including a plurality of shoes for coupling each of said pistons to said swash plate, between said suction chambers and said swash plate, so as to be slidable in said each piston.

15. The swash plate type compressor according to claim 14, wherein each one of said pistons is provided with a passage for supplying a lubricant to said shoes from said suction chambers.

16. The swash plate type compressor according to claim 8, further including a plurality of bearings for said drive shaft, a plurality of recesses for retaining said bearings, and a plurality of seal members, wherein said seal members, bearings and recesses are formed between the cylinder block and said drive shaft, in the vicinity of said discharge chambers.

17. The swash plate type compressor according to claim 16, wherein each of said seal members has a ring-shape and a generally U-shaped cross section, and wherein the open ends of said U-shaped seal members face said discharge chambers.

18. The swash plate type compressor according to claim 3, wherein said drive shaft includes a plurality of lubricant passages for supplying a lubricant to said bearings through said passage formed along said drive shaft axis.