US2745350A - Injection pumps - Google Patents

Description

May 15, 1956 R. CAPSEK 2,745,350

INJECTION PUMPS INVEIITDR:

ROGER CAPSEK hag INJECTION PUMPS v Roger Capsek, Paris, France, assignor to Bronzavia S. A.,

Courbevoie, France, a Corporation of France Application June 20, 1951, Serial No, 232,499 Claims priority, application France June 23, 1950 14 Claims. c1. 103-41 adapted to closefor a variable period of time the inlet orifices of the elementary pumps.

The following description and the accompanying drawings illustrate an embodiment of the invention:

Fig. '1 is a cross-sectiontaken along the line 11 in Fig. 2.

Fig. 2 is an axial section taken along the line 22 in Fig. 1.

Figs. -3 and 4 are sectional views on an enlarged scale of the regulator in two difierent operative positions.

The feed pump comprises a main cylindrical housing or body 1 (Fig. l), in which are housed several identical elementaryfuel pumps corresponding to the number of cylinders to be fed, a number of identical elementary. oil pumps and a single regulator or metering valve.

In the particular-embodiment illustrated in -the drawing there arefour elementary fuel pumps P1, P2, P3, P4, two elementary oil pumps H1, H2 and the regulator or meteringvalve R." v

Bodyl is closed atone end by a cover 2 (Fig. 2) secured by a nut.3 screwed on to body 1. Extending axially therethrough is a hollow camshaft 4 having at its inner end a rotau've member in the form'of 'a earn 5 and'at its outer end flutes 6 for connection with a driving member, this United States Patent 0 shaft being rotatable in a bushing 7 and a roller bearing 8 housed in cover 2. H

A spindle 9 engages hollow shaft thereby through a cross-connecting pin 10. Spindlel9 is rotatable in a bearing 11, fitted with a sealing ring 12,

which bears at one end against cam 5 and "at the other. end against bearing 11., 1

The fuel delivered by-a pump (not shown) is supplied through a coupling E (Fig. 1), screwed in-themain body, into an annular space .13-around bearing 11 and flows through ducts 14 into. the regulator or metering valve R.

Said regulatorcomprises a cylindrical casing 15 fitting in a bore of the main body and carrying opposite to each pump, such as P1, an aperture 16 in communication with two further balancing apertures 17,; situated on the diamet rically opposite generatrix, through a helical groove 18. The casing is held atone end by a connection 19, screwed inthemain body. I,

A hollow piston'va'lve 20, slidable and rotatable within cylindrical casing 15, with a very slight clearance, is formed on its periphery with a'recesszl, which is limited by a straight generatrix portion 22 (Figs. 3 and 4), an'are 23 of a helix, and a circular portionin a transverse plane, thus-.forminga depre'ssion in the solid portion- 24. Recess 4 and is actuated 1 ice 21 and the inner wall of casing 15 define a space 25,,which communicates with the apertures 16 in the cylindrical casing 15 and, through orifices 26, with the inner space of piston valve 20.

A sleeve 27, arranged within piston valve 20, has apertures 29 communicating with the apertures 26 in the pis-i valve through the medium of a groove 29a, said sleeve also Each elementary fuel pump P1 comprises a piston 34 slidable with very little clearance in a cylinder 35, housed within the main body. Said cylinder has two lateral ducts 36 and bears against a. hollow valve seat 37, which is held in place, through the medium of a gasket 38, by a connecting nipple 39, screwed in the main body and. cornmunicating with an injector (not shown).

'A valve 40, cooperating with. said seat 37, is urged inwardly by a spring 41, which bears against an abutment ring 42.

Piston 34 has a flange 43, held between the bottom of a hollow plunger 44 and a ring 45. Plunger 44 carries a 1 I roller 46, rotatable about a spindle 47 mounted in said plunger. Said roller is biased against cam 5 by a spring 43 interposed between a shoulder of main body 1' and the bottom of plunger 44. r

Cover 2 has a bore 49 parallel with the axis of the pump and which is supplied with oil, derived from the lubricating circuit of the engine, through a valve comprising-a seat 50, screwed into the main body and a ball 51, held it against the seat by aspring, bearing against a ring 52 secured to seat 50. An upper duct 49a enablesa circulation of oil to be set up through the pump, for evacuating the air contained in the main body, when the engine-is H started. An opening 53 and a conduit or duct 54 establish communication between'the inner space ofthe'main body,

into which opens bore 49, and a circular groove 55- coilimunicating with an'innerspace 55a of the oil pump body.

,Groove 55 feeds the elementary oil pumps H1, H2 each comprising a hollow plunger 56 slidable withinthemain body. and provided with lateral orifices 57 establishing communication between the interior of the plunger and an annular chamber or groove 53 surrounding casing15 and from which conduits or ducts 59 lead to the provided in the fuel pump cylinders.

' Plunger 5-5 is reciprocatejd by a roller 6%, rota-tablefon aspindle olmounted in said plunger and urged against earn 5 by a spring62, interposedlietween plunger-'56 and the rear portion of'a valve 63, which isslid'able within the hollow plunger.

spring 62, and bearing against a ring 66 having-anaxial opening 67 therein. Said opening is closed by an opposite valve 68, slidable in a cap 69, screwed into. the main body, ,a spring 70 being interposed between cap 'gi9xand valve 68. A lay-pass channel '71, surrounding valve 68, is connected With-the oil inlet passage 54. The operation is as follows: 1 Q The recess 21 in the piston valve being situated opposite the aperture 16 (Fig. 3), fuel, delivered by. a pump (not shown) through coupling E, flown successively through: the anular space 13 of bearing 11, iduts 14, slots 30 of sleeve 27, hollow piston valve .20, ..apertures 29;"groove 29a of sleeve 27, apertures 26 in the piston Patented May 15,1956

apertures 36 Said valve 63, which is bored axially, has a flange resting on a shoulder 64 ofthe main body, under the tension of a spring 65, stronger than u =upper dead centre.

arethen also minimum.

' valve, the space 25 between the casing and the piston valve, apertures l in the casing and ducts 33 into the elementary pumps P1, P2, P3, P4.

.During the rotation of camshaft 4, which through spindle 9 and turnscrew 28, rotates piston valve 2%, communication between recess 21 and apertures 16 is periodically stopped as the solid portion 24 of the piston valve comes opposite apertures 16.

' The"piston 34 of elementary pump P1, through roller "46'biased toward the cam by spring 48 is reciprocated and compresses the fuel in cylinder 35, duct 33, aper tures16; helical groove 18 and the diametrically opposed xap ert ures 17 which balance the stresses upon piston valve 20.

As the. pressure'of the fuel compressed in the cylinder attains the adjusted'pressure of the spring urging valve 40, this latter opens, and the fuel is injected under pressure into the engine cylinder through valve seat 37,

ring Rand nipple 39.

As' the shaft continues its rotation, apertures 16111? uncovered and the fuel remaining within cylinder 35 is now forced through duct 33 and aperture 16 into the interior-of the main body, until piston 34 has reached its Therefore, the duration of the injection-corresponds to the period duringwhich the apertures 16in the casing are covered by the solid portion 24 of the piston valve 29, the arrangement being such that this corresponds to the movement of piston "34 towards its'upper dead centre. According to the direction of rotation herein illustrated, the edge 23 (Fig. 3) corresponds to the beginning of theinjection and the edge 22 to the completion thereof. It will be seen, therefore,

thatthe period of injection varies in accordance with the circumferential distance between these two edges along -solid portion 42 in a transverse plane passing'through aperture 16.. Owing to'the helical shape of edge 23,

this distance decreases as piston valve moves from the left towards the right. i

Fig. 3 shows the piston valve in a position in which i the circumferential distance between the edges 22 and 23 is a maximum oppositev aperture 16. The period of injection and hence the amount of fuel injected per stroke of the piston is also a maximum.

7 between the latter.

Fig. 4 illustrates the piston valve in a position in which I the circumferential distance between the edges 22, 23

opposite the aperture 16 is a minimum. The time, of

injection' and the amount of injection per piston stroke The longitudinal position of relation to casing lS may be adjusted through the hollow nipple 19 by any suitable means, for example by a hybe at eachinstant in a state of equilibrium under the V opposing action of the pressure ofthe fluid used by the servo-motor .on the one'hand and the'tension of spring 32 and the pressure of the .fuel prevailing :within nthe piston valve on the other hand.

" "A high-pressure'oil circulating circuit ensures'the lubripiston valve 20 in drauli'c servo-motor; in such case, said piston valve would valve 68 is lifted and the oil circuit is by-passed through orifice 71 back to the oil feed duct 54.

The housings for plungers 44 and 56 communicate with the interior of the main body.

It will be understood that the invention 'is not limited tively mounted in said pump body and operatively COD-7, nected to each of said pistons for reciprocating the latter. in succession in their conjugate cylinders, parallel lubrieating oil pumps arranged on a circle in said pumpbody and each comprising a cylinder and v a reciprocative plunger therein and oil inlet and outlet ports provided in said oil pump cylinder, each plunger beingoperatively connected'to said rotative member for reciprocation their conjugate cylinders by the latter," first conduits connecting said lubricating oil inlet 'ports to a source of lubricating oil, second conduits connecting the outlet I ports of said lubricating ,oil pumps to an oil chamber,

third conduits radially'connected to the respective cylin-. V Y

ders of said fuel pumps and to said oil chamberthereby putting the oil chamber in communication with said fuel pump cylinders, and pressure relief means provided said pump body and in communication with said outlet,

ports for controlling the pressure of the oil' pumped by the lubricating oil pumps through said outlet} ports,

. whereby a supply of lubricating oil may be pumped between the piston and cylinder of said fuel pumps ata high pressure controlled by said pressure relief means and thoroughly lubricate the contacting surfaces of piston and cylinder and create an efiective fuel-tight seal 2. A fuel injection pump including a pump body, a plurality ofparallel fuel pumps arranged on a circle in said pump body and comprising eachr a cylinderand a piston reciprocatable therein, a rotative'member rotatively mounted in said pump body andoperatively con,-

nected to each of said pistons for reciprocating the latter in succession in their conjugate cylinders, parallellubricating oil pumps arranged on a circle in said pump body and each comprising a cylinder and a reciprocative plunger therein'and oil inlet 'and outlet ports, each plunger being operatively connected to rotative member V for reciprocation in theirconjugate cylinders by'the latter,

a first'oilchamber'which' is contained in said'purnp body and surrounds said rotative member and'is' connected to a source of lubricating oil, conduits connecting the lubrieating oil pump inlet ports to said oil chamber, a second 011 chamber in said pump body,second conduits conmeeting the outlet ports of said lubricating oil'pumps to 'said: second oil chamber, third conduits-radially concationj andsealing of pistons 34. Through valve 50,

which is adapted to prevent the pump fromemptying at rest,the oil successively flows through: bore'49 in cover 3 2, opening 53, duct 54 and groove 55.,

Roller :69, urged toward cam 5 by. spring 62, imparts a reciprocatory motion to plunger 56, and in the extreme position of said plunger towards the right, groove 55 is incommunication with the cylinder of the .main body where plunger 56; operates. Upon return of plunger 56 towards the left, communication between groove 55 and said cylinder is cut oh, and the oil thus admitted behind the plunger is compressed in the space'55a and lifts hollow valve 63; through said hollow valve, it enters hollow plunger 56, and escapes through orifices 57, circula'r groove 53, duct 5 and ducts 36 into cylinder35,

to secure sealing of piston 34.

When theoil pressure exceeds' a predetermined amount between the latter,

nected-to the respective cylinders. of said fuel pumps and tosai'd second oil chambertherebyputting the'second oil chamber in communication with' said fuel pump cylinders, at least one pressure relief valve-insaid pump body and incommunicatiomwith said" outlet ports for controlling the pressure of the oil pumped byv the lubrication O11 pumps, whereby a supplyoflubricating' oil may be pumped between the piston and cylinder of "said fuel pumps at a high pressure controlled by the pressure relief v valve and thoroughlydubricate the contacting surfaces of pistonand cylinder and create an effectivefuel-tight seal 7, 3. A fuel injection. pump including a pump body, a plurality "of parallel fuel pumps arranged on a circle'in said pump body andjcomprising eacha cylinder and a piston reciprocatable' therein, a rotative membenrotatively mounted in said body and operatively con-v nected to each ofsaid pistons fori-lsuiprocating.thelaittures, a rotary valve movable in said sleeve in controlling relationship to said first apertures and connected to said rotative member so as to cyclically close said first apertures in timed relation to the reciprocation of the fuel pump pistons by said rotative member, at least two lubricating oil pumps in said pump body substantially diametrically opposed on either side of said cylindrical aperture, said lubricating oil pumps comprising each a cylinder and a reciprocative plunger in the latter and oil inlet ports and oil outlet ports in said cylinder, said plungers being operatively connected to said rotative member so as to be reciprocated thereby in their respective cylinders, first conduits connecting the oil inlet ports of said lubricating oil pumps with a source of lubricating oil, an oil chamber in said pump body, second conduits connecting said oil chamber to the oil outlet ports of said lubrieating oil pumps, third conduits radially connected to the cylinders of said fuel pumps and to said oil chamber, and pressure relief means provided in said pump body and in communication with said oil outlet ports for controlling the pressure of the oil pumped by said lubricating oil pumps through said oil outlet ports. I

8. In a fuel injection pump comprising a pump body, a series of fuel pumps each including a cylinder, fuel inlet and outlet passageways and a piston reciprocatable in said cylinder, and a rotary valve rotative in a rotary valve cylinder provided in said pump body for closing in succession fuel inlet apertures which communicate with said fuel inlet passageways in timed relation to the reciprocation of the pistons, the provision of two balancing apertures in the wall of said rotary valve cylinder opposite each inlet aperture and passages in said pump body connecting each pair of balancing apertures to their corresponding inlet aperture, each pair of balancing apertures being located in a diametral plane containing said inlet aperture and the axis of the rotary valve cylinder and having a total cross-sectional area which is substantially equal to that of the corresponding inlet aperture, whereby the lateral thrust exerted on the rotary valve by the fuel pressure from the fuel pumps acting through the inlet apertures is substantially compensated by a thrust exerted by this fuel pressure on the rotary valve through their corresponding balancing apertures.

9. In a fuel injection pump comprising a pump body,

a series of fuel pumps each including a cylinder, fuel inlet and outlet passageways and a piston'reciprocative in said cylinder, and a rotary valve in said body for closing in succession said fuel inlet passageways in timed relation to the reciprocation of said pistons, the provision of a sleeve interposed between said rotary valve and said body and held fast in the latter, first apertures in said sleeve each one of which is connected to one of said fuel inlet passageways, two balancing apertures for each first aperture also in said sleeve and located on the opposite side of the am of the sleeve relative to the first aperture in a diametral plane which contains said first aperture and the axis of said sleeve, the total cross-sectional area of the pairs of balancing apertures being substantially equal to that of their corresponding first aperture, and passageways connecting the first apertures to their corresponding balancing apertures, whereby the lateral thrust exerted on the rotary valve by the fuel pressure from the fuel pumps acting through the first apertures is substantially compensated by a thrust exerted by this fuel pressure on the rotary valve through their corresponding balancing apertures.

10. In a fuel injection pump comprising a pump body, a series of fuel pumps each including a cylinder, fuel inlet and outlet passageways and a piston reciprocative in said cylinder, and a rotary valve in said body for closing in succession said fuel inlet passageways in timed relation to the reciprocation of said pistons, the provision of a sleeve interposed between said rotary valve and said body and held fast in the latter, first apertures insaid sleeve each one of which is conncted to one of said fuel inlet passageways,

sleeve and located on the opposite side of the axis of the sleeve relative to the first aperture in a diametral plane which contains said first aperture and the'axis of said sleeve, the total cross-sectional area of the pairs of balancing apertures being substantially equal to that'of their corresponding first aperture, and helical passageways provided between said sleeve and said pump body, each helical passageway connecting each first aperture to its corresponding balancing apertures, whereby the lateral thrust exerted on the rotary valve by the fuel pressure from the fuel pumps acting through the first apertures is substantially compensated by a thrust exerted by this fuel pressure on the rotary valve through their corresponding balancing apertures. 7

11. A fuel injection pump as claimed in claim 10, wherein said helical passageways comprise helical grooves provided on the outer cylindrical wall of said sleeve.

12. In a fuel injection pump comprising a pump body, a series of fuel pumps each including a cylinder, fuel inlet and outlet passageways and a reciprocative piston in said cylinder, said pistons being reciprocated by a.

rotative member, the combination with said pump body of a sleeve held in a fluid-tight manner in the latter, first apertures in said sleeve each one of which is connected to one of said fuel inlet passageways, a rotary valve rotative in said sleeve and adapted to "close in succession said first apertures in timed relation to the reciprocation of said pistons, two balancing apertures for each first aperture also in said sleeve and located on the opposite side of the axis of the sleeve relative to. the first aperture in a diametral plane which contains said first aperture and the axis of said sleeve, the total cross,- sectional area of these balancing aperturesbeing substantially equal to that of their corresponding first apertures, and passageways connecting the first apertures to their corresponding balancing apertures, whereby .the lateral thrust exerted 'on the rotary valve by the fuel pressure from the fuelpumps acting through the first apertures is substantially compensated by a-thrust exerted by this fuel pressure on the rotary valve through the corresponding balancing apertures. t

13. In a fuel injection pump comprising a pump body, a series of fuel pumps each including a'cylinder, fuel inlet and outlet passageways and a. reciprocative piston in said cylinder, said pistons being r eciprocate d by a f rotative member, the combination With said pump body of a sleeve held in a fluid-tight manner in the latter, first apertures in said sleeve each one of which is 'connected to one of said fuel inlet passageways, a rotary valve rotative in said sleeve and adaptedto close in succession said first apertures in timed relation to the reciprocation of said pistons, two balancing apertures for each first aperture also in said sleeve andlocated on the opposite side of the axis of thesleeve relative to the first aperture in a diametral plane which contains said first aperture and the axis of said sleeve, the total cross-sectional area of these balancing aperturesbeing substantially equal to that of their corresponding'first apertures, and helical passageways provided between said sleeve and said pump body, each helical passageway connecting each first aperture to its corresponding balancing apertures, whereby the lateral thrust eXerted onthe rotary valve by the fuel pressure from the fuel pumps acting through the first apertures is substantially compensated by a thrust exerted by this fuel pressure on the rotary valve through their corresponding balancing apertures.

14. A fuelinjection pump as claimed in'clairn 1 3 wherein said helical passageways comprise helical grooves provided on the outer cylindrical wall of said sleeve.

(References on following page) cy i s-t "6 'In a fuel injectionpump. including a pump body,

tore in succession": in-t'their: conjugate: cylinders, parallel V lubricating oil pumps arranged on a circle: in said pump body andieach including a cylinder and a plunger reciprocatable therein and an oil inlet port and an oil outlet 7 Said-cylinder, means for holding said fplungers-in 7 operative'connection with said rotative member, means associated' with saidplungers-for obturating said oil inlet port during, a part of the pressure stroke ofisaid plunger, first conduits connectingthe oil inlet ports of said lubrieating oil pumps toasource of lubricating oil, second conduits connecting, the oiloutlet ports to an'oil chamber,

conduitsradially connected tozthe respective cylinders.of-said fuel pumps-and to said oilchamber thereby I putting-the oil chamber incommunicating with said fuel Pump cylinders, and pressure relief means provided in said' I pumpibodyand in communication with said outlet ports for controlling. the pressure ofthe oil pumped by the lilbrij iajting pintrips throughv said outlet ports, whereby a suppl yof lubricating. oil may be pumped between the Q' plistoniand cylinderof-said fuel pumps at ahigh pressure 7 controlled by said. pressure relief means-and thoroughly lubricate the' connecting-surfaces of piston and cylinder andj createan efiective fuel-tight sealbetween the latter.

l-41 In a fuel injection: pump including a pump body,

' 'a'series'of fuel pumps arranged about; an axis in the:

' latter comprising.each a cylinder and'a' piston reciproc'atableithereimin combination, a rotative member in said pump body and mountedito rotate about saidaxis,

jsaidjpistons being.operatively connected to said rotative member Qfortheir reciprocation in' their conjugate cylindersby said rotativ'evmember, lubricating oil pumpsarranged about said insaid pump body and each including acylinder and a reciprocativetplunger therein j and oilfinlet and outlet ports insaid cylinder, first conduits connecting the re'spective oil inlet ports toa source of lubricating oil; {an oil chamber in' said 'pump body,

x'second conduits connecting the respective oil outlet ports tosaid} oil chamber, third conduits radially'connected to the cylinders of 's'aid-ifuel pumps :and to'said oil chamber,

pressure ,relief means in said "pump body and in communication-With said oil outlet'po'rts for controlling the pressure"ofthe'lubricating' oil pumped by the lubricating oil pumps, and means. for maintaining said' plungers' in operativeieonnection with said'rotativemember sothat the latter-yreciprocatessaid; plungers in their conjugate 5.- In afuel infection including ajpump'body,

f a series offuelpumps arranged about an axis in the latter and'comprising each a cylinder and a piston reciprocatable therein, in combination, a rotative member in saidvpump' lb'o'dy 'and mounted to rotate: about said axis, said pistons being operatively connected to said' rotative member for tl eirireciprocation"intheir conjugate cylinders by said rotative member, lubricating oil pumps arranged about.

said a is insaki'zipu mp body and comprising each a cylin-t defanda reciprocating plunger thereinnd oil inlet and outlet ports in said cylinder,'-a 'first oil chamber contained within said 'pumpbody andsurrounding, said rotative member, ,saidi first oilv chamber being connected to a -sou1 ce;of-lubricating oil,first conduits connecting the oil inletports to said first oil chamber, a second oil chamber insaid pump body second. conduits connecting the oil outlettports to said'second oil chamber, third conduits radially connected to the cylinders of'said fuel pumps and:,to said secondoil chamber thereby putting the secondioill chamberin communication with the contacting surfaces of piston and cylinder in said fuel pumps, presa series of fuelpumps arranged abouta'niaxis" inithelatter and comprising each a cylinder anda pistonlrecip'rocatable therein, a rotative member in said' pump; body" and mounted to rotate about said axis,;said pistons being-operatively'connected tosaid rotative member for their: re

ciprocation in their conjugate cylinders by said-rotative member, at least two parallel: lubricating oil pumps positioned in said pump body substantially diametrically. opposite on either side of said axis, each lubricating oil pump unit comprising, acylinder having-a closed end and an open end, an oil inlet port and an oiloutlettporttin said cylinder, a hollow plunger having a closed-end and an H open 'end and reciprocatable in said' cylinder, oil' outlet aperture provided'in said'plunger at'such position therein 7 and having such length in the direction of. reciprocation of said hollow plunger: that the interiorfof the plunger is in constant communicationltherethrough withsaid'oil' outlet port, a valve piece having antaperture'thronghout its length, a portionof this valve piece being slidably mounted in theopen end of the hollow plunger, 21 flange portion constituting a seatingsurface included in said valve piece at the end thereof remote from the closed end vof the hollow plunger, the major-diameter of saiddiange being. less'than the diameter of said cylinder, an "annular shoulder constituting a. seating surface provided in 'said cylinder: and having a minor diameter which is greater thanxthe' outside, diameter" of theapqrtion'of saidi'v'alve piece which is slidable-in said'hollow plungerQsaid an n'ular shoulderw having a positiorrbetweenthe open. end of the hollow plunger and-the flange portion ofthe; valve j: piece and facing this flange portion so? thatfsaidfseating surfaces are capableof' engaging one another, a spring interposed between the closed end. 'ofgthecylinder and; the

valve, piecefor urging-jsaid flange: portion'against: said annular shoulder andv thereby cause" said seating-surfaces toengage one another, means; for maintaining-theclosed end of the hollow plunger in constant. operative; con: I

nection with said rotative member, and said'inletport having suchposition between said. annular shoulder and the open end ofythe hollow plunger'when; the latter is at the beginning of its pressure s trokethatsaidinlet port is obturated by the hollow plunger for apart of itspressure stroke and the hollowvplunger exerts a pressure on p I the oil thereby trappedin the annular space betweenrthe cylinder the valve piece and the end ofthe plunger, and raises the flange portion of the valve piece oif the annular shoulder against: the restraint of 'said s'pringtand urges the oil pastlthe flange portion of the valve piece, through the aperture in the latter, into the hollow plunger and thencethrough the oil outlet aperture and the oil outlet port without ,occasioningatany time any: loss ofoil pressure through said inlet'port, pressure relief means being provided in said pump body andin communication with said oil outlet portsfor controlling the pressure of the lubricating-oil pumped by the lubricating oil pumps.

, 7.. A fuel injection pump comprising, in combination, I 'a pump body having a'cylindrical aperture therein, a

series of fuel pumpsl'disposed in said pump body about said aperture, said fuel pumps comprising'each a cylinder and a piston reciprocatable thereinand fuel inlet and outlet passages in said cylinder, arotativeimember coaxial with said cylindrical aperture and operatively connected' to said pistons to reciprocate the :Iatter in their conjugate cylinders, acylind'ricalsleeve immovably' held in said cylindrical aperture in a fluid-tightmanner, first apertures in said sleeve each one of which. isj connected to one of said fuel inlet passages, at least twosecond apertures also providedrin said sleeve for each first aperture and having such position as to lie substantiallyain the diametral plane passing through said'-first-xapertureand the axis of said sleeve, the total cross sectional area of these second-apertures being substantially equal'to that of their respectivefirst apertures,'r;passage ways jconnecting first apertures to their respective second-taper- References Cited in the file of this patent UNITED STATES PATENTS Walker July 4, 1916 Eckels Sept. 13, 1932 Parsons Sept. 21, 1937 Lauret Oct. 4, 1938 Alden Jan 3, 1939 Pool Oct. 27, 1942 Truxell, Ir. Sept. 5, 1944 10 10 Beeh et a1. July 31, 1945 Beeh Aug. 20, 1946 Smith Mar. 11, 1947 Benedek Sept. 2, 1947 Beeh Aug. 31, 1948 Parker Ian. 4 1949 Huber Feb. 8, 1949 Groves June 28, 1949

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