US2394285A - Pump - Google Patents

Description

Feb. 5, 1946. l J. 5. BEvlNs PUMP 4 Sheets-Sheet 1 l Filed July 27, 1944 I INVENToR. .fas/zes Feb. 5, 1946.

J. E. BEvlNs PUMP Filed July 27, 1944 4 Sheets-Sheet 2 l fn BY www.

A T TRNE Y J. E. BEVINS Feb-5, 1946.

PUMP

Filed July 27. 1944 4 Sheets-Sheet 5 A INVENToR. @412519. Bevins. l

Feb. 5, 1946., J. aBEvlNs 2,394,235

PUMP

Filed July 27, 1 944 4 sheets-sheet 4 "maf" JNVENTOR. .faz/ces L'. BewzA 'ATTRNEY Patented Feb. 5, 1946 PUMP James E. Bevins, Ramsey Estates, N. J., assigner to Bendix Aviation Corporation, Teterboro, N. .La corporation of Delaware Application July 27, 1944, Serial No. 546,764

19 Claims. (Cl. 103-182) The present invention relates topum'ps and more particularly to a novel structure for radial piston pump of the high pressure type.

In the use of the term high pressure Ais meant pressures in excess of 3000 lbs. Heretofore, it has been diilicult to provide a. pump for operation at such high pressures due to the inertia of the.

mOVing parts and the attendant peripheral velocities of the bearing surfaces.

In order to overcome the foregoing diilculties, an object of the invention is to provide a crank shaft of relative small diameter for operating a `plurality of shoes which have for their bearing surface a recess lled with hydraulic fluid. The fluid serves as a hydraulic bearing between the shoes and an eccentric or abaxial actuating member, while the shoes serve as seals for the bearing liiuid and as supports for radially extending pump pistons. l

Another object of the invention is t provide a novel radial piston pump which will supply hydraulic uid at high pressures for use in hydraulic systems particularly in aircraft.

Another object of the invention is to provide a compact pump of great efliciency in comparison to its size and of such simplicity in construction as to adapt it for convenient and rapid manufacture and assembly at low cost. I

Another object of the invention is to so arrange the oil bearing in relation to the pump piston that neither iioating of the shoes, nor seiz' ure betweenthe shoes and crank shaft will result at the high speeds and pressures to which the pump pistons are subjected.

Another object of the invention is to provide a novel tting for the shoe and piston, whereby the shoe and piston may readily wear to a superior t'and seal with continued operation.

Another object ofthe invention is to provide a. hollow piston sleeve having a wall of such material and thickness as to be readily adapted to *eiect a limited expansion with high pressures for reducing the clearance between the piston and cylinder wall in order to maintain between the piston and cylinder wall a substantially negligible leakage upon pressure increase.

Another object of the invention is to provide novel means for connecting a plurality of pump pistons in driving relationalong the periphery of an eccentric driving member.

Another object of the invention is to providea novel ring means for securing the pump pistons in driving relation along the periphery of an ec.

centric driving member so as to transmit movement from the eccentric to the pistons.

The above and further objects and novely features of the invention will more fully appear from the following detailed description and the accompanying drawings wherein one embodiment of the invention is illustrated. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not designed as a definition of the limits of the invention, reference being had for this purpose to the appendedclaims.

In the drawings, wherein like reference characters refer to like parts in the several views,

Figure 1 is a perspective view of a pump embodying my invention with a portion thereof broken away so as to better illustrate the inner' .f arrangement of the same;

Figure 2 is a longitudinal sectional view of-a preferred form of pump embodying my invention;

Figure 3 is a view of one end of the pump shown in Figure 2;

Figure 4 is a view of the opposite end ofthe pump from that shown in Figure 3;

v Figure 5 is a somewhat diagrammatic crosssectional view illustrating the arrangement of the pump pistons about the eccentric operating mem- Figure 6 is a fragmentary view of the fastening clip for the novel piston connecting-ring; e.

Figure 7 is an enlarged fragmentary sectional view illustrating the relationship between the plston and shoe; and

Figure 8 is a fragmentary sectional viewof Figure 7.

Referring now to the drawings, the invention will be described as applied to the pump shown in- Figure 2, like numerals, however, indicating like parts in the form shown in Figure 1.

As shown, there is provided a housing, casing or casting I having formed therein a pump chamber 2. End plates 3 and 4 are mounted at opposite ends of the casting I by suitable bolts 5 and 6 respectively.

The end plate 3 has rotatably mounted therein a shaft l on which are'mounted eccentric or abaxial actuating members indicated by thenul meral I and positioned in the chamber 2. A flexible coupling member I is suitably connected at the outer end of the shaft I and arranged to connect the shaft I to a 'suitable driving motor not shown. The shaft I is mounted at the opposite y ends in suitable anti-friction bearings II and II carried by the end plates I and 4, respectively.

Asshowninlllgurea,theltliusI2 arelock'ed The end plate 4 has provided thereon inlet,

and outlet connectors I2 and II, respectively. The inlet connector I2 is arranged to be connected to a suitable source of fluid medium such as oil and leads through a passageway I4 formed in the end centric members I. Slidably mounted along the peripheral edge of each ot the eccentric members I are a plurality of `shoes each indicated generallyby the numeral I'I. Each of the shoes il is curved at the inner surface so as to 'slide along the periphery of the cooperating eccentricmember I and has provided a recess II formed in the inner surface surrounded by an outer, edge IIB, as best shown in Figures 'I and 8. A passage 2l extends through the shoe I I from the recess II and is arranged to cooperate with the passage iI,-upon the eccentric member I being turned so as toposition the opening II opposite the open- Further formed in the shoe I1' at the outer side thereof is a recess or seat 2I having a spherical radius. Riding within the 'recess 2| is a semispherical end 22 of a piston sleeve member 22.

in position in the shoes I1 by bands or rings II, which are positioned in the arcuate slots I4 at opposite sides of the shoes I I, so as to hold the shoes in engaging relation along the periphery of its Acorresponding eccentric member I. 'l'hree flexible clips II, as shown in Figures 5 and 8, are provided for fastening the rings in position. Each clip II has a projecting clip part I'I, which is first positioned under the lower edge of one ring I5 and the other end then snapped over the other ring I5. as shown in -Figure 6, so as to fasten the rings I5 in position and the shoes II in contacting relation along the surface ci' the eccentric member I.

It will be seen that surrounding the recess II formed in the inner surface of the shoes Il is the edge IIB adapted to engage the surface of the eccentric member .8 and seal within` the recess I9 the aforementioned hydraulic fluid.

The hydraulic uid carried within the recess II, thus 'serves as a bearing, and the shoe II through the edge IIB serves as a seal for such bearing huid. It will be seen, however, that under pressure the hydraulic uid will tend .to spread under the edge IIB lubricating the surface between the edge IIB and the surface of the eccentric I. However, in order to prevent the shoes I1 from tending to "oat under the extreme hydraulic pressures and speeds to which the pump is subjected, the surface area of the y shoe I1 subject to such floating pressure is matched against the total surface area of the piston 22 exposed to a counteracting iiuid pressure 35 so that the total area of the shoe i'I under a fluid pressure tending to float the shoe I'I, will be The piston sleeve 23 is open at the opposite ends less 'than the total surface area tending to hold thereof, and is arranged to slidably move within a cylindrical chamber 24. l

Two sets of cylindrical chambers 24 are'drilled in the casting l and radiate from the chamber 2 from points opposite the respective. eccentric members I, as possibly best shown in Figures 1,'2, 4and 5. chambers 2,4 are the piston sleeves 2I. The outer ends of the cylindrical chambers 24 are closed by ,plugs 2l which "are positioned on resilient seat member 24. vThe plugs 2l j have projecting inwardly therefrom stems 21. The stems 2l co- 'Operate with corresponding piston sleeves 2I so Y or shell 2l nts tightly about the outer surface `the shoes in contacting relationwith the eccentric member IL Thus the iluid pressure applied Reciprocably mounted in the cylindrical f force tending to force the shoe I9 toward the eccentric member I. 'However'. the difference between such counteracting pressure areas is sufficiently small and the bearing areasbetween the edge IIB 'and eccentric member I sufficiently great-that seizure will not result at the high velocity and pressures at which the pump is op- `of the casting I. securing the plugs 2l in position 4shoe .I'I into arcuate slots I4 formed therein.

Due to the novel semi-spherical shape of the end 22of the piston sleeve II and the recess 2i in which the end 22 is seated, the piston sleeve II and shoe I1 are self-aligning at all times-so that the connecting rod II for the piston 2I does not carry any appreciable load during the compression stroke of the piston sleeve 2I. Therefore. the connecting rod'II need only be provided .cf a size and strength ample to carry the relative light load of returning the l piston sleeve 2I o n the suction stroke. Y

erated. The structure of the shoe I1, illustrating my novel fluid bearing arrangement in relation to the piston 22, is probably best shown in -Figures 'l and 8, wherein the comparative area ,Where oil is used, the shoes II may be formed of leaded phospho-bronze or any other suitable material lubricated by oil. v

.I have further provided an additional novel feature in my invention in that the Vpiston sleeve 22 is formed of a suitable expansible material..` v

such as steel. The wall of the piston sleeve 2I is further formed sufficiently thin, between vthe shoulder 2s' and end 23A, that a minute limitedexpansion of the latter vportion of the wall of the piston sleeve 23 will result at the high pressures and thereby reduce the clearance between the piston sleeve 23 and the cylinder wall 24 when subiectedto such high pressures. The latter expansion is sufllcientlyvlimited, however, as not to effect seizure between the piston sleeve and cylinder wall. Thus there is maintained a'substantially negligible leakage between the piston sleeve 23 and the cylinder Wall 24 as the fluid pressure within the cylinder increases. i

As shown in Figures 1 and 2, an outlet passage 38 formed in the casting I leads from the cylindrical chambers 24, into a second passage 39 formed in the end plate t, which passage 39 in turn opens into a main collecting passage 40 formed in the end plate II. The main collecting passage 40 leads through a passage il into the outlet connector I3, which is arranged for connection to a suitable outlet conduit not shown.

A check valve 132 is positioned between each of the passages 38 and 39 and is biased to a closed position by a spring 33 which is counteracted by outlet pressure from its corresponding cylindrical chamber 2li. The check valve 32 isfbiased to a closed position upon suction pressure being exerted in the corresponding cylindrical chamber 24.

The aforenoted pump mechanism provides novel means for facilitating the convenient and rapid assembly of the mechanism.y Thus in assembly, the pin 3U is first inserted togetherwith the rod 3| into the outer end ofthe piston 23 so that the pin 30 rests on the shoulder 29 and the rod 3| extends through the opposite end of the sleeve 23. The ends 22 of the pistons 23 are then seated in the respective recessed portions 2 I of the shoes Il and the pin 21 inserted in the holes 33 in the shoe Il so as to engage in the rod 3I. The

two sets of shoes Il and pistons 23 may then be assembled in position by a ring 35, which is placed in each case at the opposite side from that of the open ends ofthe casting I. The eccentric members 8 may then be inserted into chamber 2 in operative relation to the shoes Il, whereupon the companion rings 35 may then be placed in the groove 29 of the shoes Il adjacent the opposite ends of the shaft 7. The two rings 35 may then be fastened in position by means of the snap clip 36, as explained, whereupon the pistons 22 are y then assembled for operation upon the fastening of the end plates 3 and 4 in position at the opposite ends of the casting I, as shown in Figures 1 and 2.

In operation it will be seen that upon rotation of the shaft "I oil or other suitable hydraulic fiuid medium will be drawn into the passageway I5 through the connector I2, flooding the interior of the chamber 2 through the passageways I6 opening into the chamber 2.

Due to the nature of the eccentric members 8 and the corresponding slots I6, it will be seen that ,the same when rotated will constitute a centrifugal pump having. a supercharging effect, whereby there is provided a charging head which is greater than the pressureat the inlet I2.

Moreover, upon rotation of the eccentric members 8 by the driving shaft 1 the shoes Il following the periphery of the eccentric members 8, due

. to the action of the rings 35, will cause the corresponding pistons or sleeves 23 connected to the shoes I1 by the rods 3| to reciprocate in their respective cylindrical chambers 2d. Movement of the sleeves 23 inwardly toward the shaft 'I will cause a partial vacuum to be set up within the cylindrical chamber 23. 'I'hus upon the arcuate slot I6 coinciding with the opening I9 of the shoe Il, as shown in the Figure 5, the uid medium `liuid medium within the piston sleeve 23 and cylindrical chamber 24 so as to force the fluid medium into the passage 38. The check valve 42 under force of the fluid medium will then be i biased to an open position, whereupon the iiuid medium will pass under pressure of the pistons 23 through the passages 38 and 39 and i0 and out the outlet I3.

Although only two embodiments of the invention have been illustrated and described, various changes in the form andrelative arrangements of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention. Reference is, therefore, to be had to the appended claims for a deflnition of the limits of the invention.

What is claimed is:

1. A pump comprising a casing, a main chamber provided therein, an eccentric member rotatably mounted in said chamber, a radially directed secondary chamber provided in said casing, a radially directed piston sleeve reciprocably mounted in said secondary chamber, cooperating fluid inlet port means provided in the eccentric member and periodically opening into said piston sleeve for supplying undercentrifugal force a uid medium through said sleeve to said secondary chamber, fluid outlet means from said secondary chamber, and means operably connecting said piston sleeve to said eccentric member for imparting a reciprocating movement thereto.

2. A pump comprising a casing, a main cham-` ber provided therein, an eccentric member rotatably mounted in said chamber, a set of radially directed secondary chambers provided in said casing, a set of radially directed piston sleeves reciprocably mounted in said secondary chambers, a set .of shoes slidably positioned on said eccentric members each of said pistons having ant end operably connected to one of said shoes, means operably connecting said shoes to said eccentric member whereby upon rotation of said eccentric Imember reciprocable movement `may be imparted to said vpistons, fluid conduit' means provided in said shoes and eccentric member for conducting a fluid medium into said sleeves and rocably mounted in said secondary chambers,

supplied through the passage I5 will be drawn by suction and' under pressure of the charging head aforesaid, into the cylindrical chamber 24.

Upon further rotation of the eccentric members 3 causing an opposite reciprocating movefluid inlet and outlet means for said secondary chambers, a set of.shoes slidably positioned on said actuating member, each of said shoes having a recess formed in the outer surface thereof and said recess having a spherical radius, each of said pistons having a semi-spherical end positioned in -one of said recesses, coupling means Afor pivotally connecting said pistons to said shoes,

and meansoperably connecting said shoes to said actuating member, whereby upon rotation of said member reciprocable4 movement may be imparted to said pistons.

4. A pump comprising a casing, a main chamber provided therein, an eccentric member rotatably mounted insaid main chamber, a radially directed secondary chamber provided in said casing, a piston sleeve reciprocably mounted in said secondary chamber, a shoe slidably positioned ou.-

member whereby upon rotation of said eccentric Y member reciprocabie movement may be imparted to said piston, cooperating port means provided in said` eccentric member and shoe and opening in to. said sleeve for supplying a uid 4medium through said sleeve into said secondary'chamber, and fluid outlet means for said secondary chamber. Y

5. A pump comprising, a casing, a main chamber provided therein, an eccentric member rotatably mounted in said main chamber, a radially directed secondary chamber provided in said casing, a piston reciprocably mounted in said secondary chamber, fluid inlet and outlet means for said secondary chamber, a shoe slidably pom- `tioned on said eccentric member, said yshoe having a recess formed in the outer surface thereof and said recess having a spherical radius, said piston having a semi-spherical end positioned in for pivotally connecting one end of said rod to said piston, a second pin for pivotally connecting the opposite end of said rod to said shoe, and

one of said recesses, a connecting rod, a nrst pin independent band means for operably connecting said shoe to said eccentric member, whereby upon rotation of said eccentric member reciprocable movement may be imparted to said piston.

6. A pump comprising a casing, a main chamber provided therein, an eccentric member rotatably mounted in said main chamber, a radially directed secondary cylindrical chamber providedin said casing, a piston sleeve reciprocablyv mounted in said secondary chamber, a shoe slidably positioned on said eccentric member, said piston sleevel having an end operably connected to said shoe, a iirst uuid inlet'port formed in s aid eccentric member and opening radially from said eccentric member, a second port extending member, reciprocable movement may be imparted to said piston sleeve.. Y

8. A pump comprising a casing, a chamber formed in said casing. a piston sleeve reciprocably mounted in said chamber, a fluid inlet port opening into one end of said piston sleeve, and a fluidoutlet port opening from said chamber at the opposite end of said piston sleeve, said piston sleeve being formed of an expansible material',4

one portion of said piston sleeve being formed relatively thinner than the remaining portion of said sleeve so that` expansion of the sleeve at said one portion may be effected upon an increase in the iiuid pressure within `the piston sleeve so as to decrease iluid leakage between the piston sleeve and the inner surface of the chamber, and means for imparting a reciprocating movement to said piston sleeve in said chamber. including means for opening and closing said iluid inlet port to said piston sleeve in timed relation to said reciprocating movement.

9. A pump comprising a casing, a chamber formed in said casing, a piston sleeve reciprocably mounted in said chamber., a fluid inlet port opening into one end of said piston` sleeve, and

Va. iluid outlet port opening from said chamber at the opposite'end of said piston sleeve, said piston sleeve being formed oi an expansible machamber, including means for opening and closing said fluid inlet port to said piston sleeve vin s timed relation to said reciprocating movement,

through said shoe and said second port being successively opened and closedto said rst fluid inlet port, and said second port opening into an end of said piston sleeve, a third iluid outlet port formed in said casing and opening from said cylindrical chamber at the opposite end of said piston, and means operably connecting said shoe to said eccentric member, whereby upon rotation of said eccentric member reciprocable movement may be imparted to said piston sleeve.

1. A pump comprising a casing, a main chamber provided therein, a rotatable actuating member mounted in said main chamber, a radially directed secondary cylindrical chamber provided in said casing, a piston sleevey reciprocably mounted in said secondary chamber, a shoe slidably positioned on said actuating member, said piston sleeve having an end operably connected to said shoe, a nrst duid inlet port formed in said actuating member and opening radially from said member. a secondport extending through said shoe. said shoe having `formed in the Amember -contacting surface thereof a recess into which saidsecond port opens, said recess for entrapping a fluid medium in such aLimanner as to form a iluid bearing for the shoe'said recess being and valve means for 'opening and closing said outlet port in response to the forces effected by said piston.

l0. A pump comprising a casing, a main chamber formed therein. an eccentric means rotatably the opposite end of said piston sleeve, said piston sleeve being formed of an expansible material,

one portion of said piston sleeve being formed relatively thinner than the remaining portion of said sleeve so that expansion of the sleeve at said one portion may be effected upon an'increase in the fluid pressure within the piston sleeve so asto decrease iiuid leakage between the piston sleeve and the inner surface of the cylindrical chamber, and means operabiy connecting said piston sleeve to said rotatable eccentric means for imparting a reciprocating movement to said piston sleeve and said eccentric means opening and closing said successively opened and closed to said iirst fluid fluid inlet port in timed relation to said reciproeating movement. v

1l. A pump comprising a casing, a main chamber formed therein, a rotatable eccentric member mounted in said main chamber, a radially directed secondary cylindrical `chamber formed in said casing, a piston sleeve reciprocably mounted in said secondaryV chamber, a shoe slidably positioned on said eccentric member, said piston sleeve having an end bearing upon said shoe and operably connected thereto, a iirst fluid inlet port formed in said eccentric member, said port opening radially from said eccentric member, a second port extending through said shoe, said shoe having a recess formed in the surface contacting said eccentric `member into which recess said second port opens, said recess provided for entrapping a fluid medium in such a manner as to form a fluid bearing between the shoe and the rotatable eccentric member, said recess -being successively opened and closed to said first iiuid inlet port by said eccentric member upon rotation thereof, said recess opening through said second port into one end of said piston sleeve, the area of the opposite end surfaces of said piston sleeve being acted upon by the pressure of the fluid mcdium within said cylindrical chamber in such a manner as to cause said piston sleeve to be forced in 'a direction toward said eccentric member against the biasing force of the fluid medium acting within said recess and against said shoe so as to thereby prevent oating of said shoe from the surface of said eccentric member a third uld outlet port leading from said cylindrical chamber at said opposite end of said piston, and said ment to said piston sleeve upon the rotation thereof.

12. A pump comprising a casing, a main chamber formed therein, an eccentric member rotatably mountd in said chamber, a set of radially .directed secondary chambers formed in said casrecess formed in the outer surface thereof and said recess having a spherical radius, each of said pistons having a semi-spherical end positioned in one of said recesses, coupling means for pivotally connecting said pistons to said shoes, a pair of rings operably engaging said shoes at the opposite sides thereof in such a manner as to hold said shoes in contacting relation with said eccentric member, snap spring members for coupling said rings together at the opposite sides oi said shoes, whereby upon rotation oi said eccentric member reciprocable movement may be imparted 'to said pistons.

13. A pump comprising, in combination, a casting, a main chamber formed therein, an eccentric member rotatably mounted in said main chamber, a set of radially directed secondary cylindrical chambers formed in said casting, a piston sleeve reciprocably mounted in each of said secondary chambers, a separate shoe for each of said pistons, said shoe being slidably positioned on said eccentric member, said shoe having a recess formed in the outer surface thereof, and said recess having a spherical radius, each of said pistonshaving a semi-spherical end positioned in sleeve, a second pin for pivotally connecting the opposite end of said rod to said shoe, a pair of annular rings operably engaging said shoes at the opposite sides thereof in such a manner as to hold said shoes in contacting relation with said eccentric member, and means for securing said rings at the opposite sides of said shoes, whereby upon rotation of said member reciprocable vmovement; may be imparted to said piston sleeves.

14. A pump comprising, in combination, a casing, a main chamber formed therein, an eccentric member rotatably mounted in said main chamber, a set vof radially directed secondary cylindrical chambers formed in said casing, a piston sleeve reciprocably mounted in each of said secondary chambers, a separate shoe for each of said pistons, said shoe being slidably positioned on said eccentric member imparting a reciprocable moveeccentric member, said shoe having a rst recess formed in the outer surface thereof, and said recess having a, spherical radius, each of said pistons having a semi-spherical end positioned in the first recess formed in its corresponding shoe for maintaining alignment between said shoe and piston, a first fluid inlet port formed in said eccentric member and opening radially from said member, second ports extending through each of said shoes, each of said shoes having a second recess formed in said shoes into which said second pled to its corresponding shoe by means including l a connecting rod, a first pin for pivotally connecting one end of said rod to the piston sleeve, a secthe recess formed in its corresponding shoe for maintaining alignment between said shoe and piston, a first fluid inlet port formed in said eccentric member and opening radially from said member, second ports extending through each of said shoes, said second ports being successively opened and closed to said fluid inlet port, and each of said second ports opening into one end of said piston sleeves, third fluid outlet ports formed in said casting and opening from each of said secondary chambers at the other end of each of said piston sleeves, each of said piston sleeves being coupled to its corresponding shoe by means including a connecting rod, a first pin for pivotally connecting one end of said rod to the piston ond pin for pivotally connecting the opposite end of said rod to said shoe, a pair of -annularrings chambers formed in said casing, a piston sleeve reciprocably mounted in each of said secondary chambers, said piston sleeve being formed of an expansible material, whereby expansion of the sleeve may be eiected upon an increase in the iluid pressure within` the piston sleeve so as to decrease fluid leakage between the piston sleeve and the inner surface of the secondary cylindrical chamber: a separate shoe for each of said pistons, said shoe beingl slidably positioned on said'eccentric member, said shoe havinga rst recess formed I in the outer surface thereof, and said recesshavinge. spherical radius, each of said pistons having a semi-spherical 'end positioned in the first recess,

formed in its corresponding shoe for maintaining alignment between said shoe and piston, a iirst fluid inlet port formed in said eccentric member and opening radially from said member, second ports extending through each of said shoes, each of said shoes having a second recess formed in said shoes into which said second port opens. said second recess provided for entrapping a fluid medium in such amanner as to form a tluidbearing between the shoe' and the surface of the rotatable eccentric member, the second recesses of said A shoes being successively opened and closed to said fluid inlet port, and each of said'second ports opening into one end of its corresponding piston sleeve, third iiuid outlet ports formed in said casing and opening from each of said secondary chambers at the other end ofeach of said piston sleeves, each of said piston sleeves being coupled contacting relation with=said eccentric member and means for securing said rings at the opposite sides of said shoes. whereby upon rotation of said eccentric member reciprocable movement may be imparted to said piston sleeves.

16. A pump comprising, in combination, a casing, a main chamber formed therein, an eccentric member rotatably mounted in said main chamber, a set of radially directed secondary cir--v lindrical chambers formed in said casing. a piston sleeve reciprocably mounted in each of said secondary chambers, said piston sleeve being formed :,soaass 17. A pump comprising a chamber, a piston sleeve slidabiy mounted in said' chamber. an eccentric member for actuating said piston sleeve in said chamber, a shoe contacting said member and operably connected to said piston sleeve, a recess formed in the contacting surface of said shoe for entrapping a fluid medium during the pressure stroke of said piston sleeve so as to form a fluid bearing between the shoe andthe member, said piston sleeve at one end engaging said shoe for reciprocable movement by said member,

the surface areas of said shoe and piston sleeve.

being so arranged that the nuid medium acting upon said shoe in'a direction to tioat said'shoe from olf said' member will be overbalanced by the forces of said fluid medium acting upon said piston sleeve in a direction to force said shoe into contacting relation with said member.

18. A. pump comprising a casing. a main chamber formedtherein. a pairoi' axiallyspacedrotatable eccentric members mounted in said chamber, two sets of axially spaced radially directed e secondary cylindrical chambers formed in said oi' an excansible material, whereby expansion of the sleeve may be eil'ected upon an increase in the fluid pressure within the piston sleeve so as v to decrease fluid leakage between the piston sleeve and the inner surface-of the 'secondary cylindrical chamber, a separate shoe for each of said'pistons, said shoe being' suoably positioned on said eccentric member, said shoe having a iirst recess formed in the outer surface thereof, and

said recess having a spherical radius, each of said pistons having a semi-spherical end positioned in the nrst recess formed in its corresponding shoe for maintaining'alignment between said shoe and piston, d. om num inlet port formed 1n said eccentric member and opening radially from said member, second ports extending through each of said shoes. each of saidshoes having a second recess formed into which said second port opens. said second recess provided for 'entrappins a fluid medium in such a manner as to form a iluid bearingbetweenthe shoe and the surface of the rotatab'e eccentric member, the second recesses of said shoes being successively opened and closed to said fluid inlet port. and each of said second -ports opening into one end of its corresponding piston sleeve, third nuid outlet ports formed in said casing and opening from each of said secpiston sleeves, 'each of said piston sleeves being coupled to its corresponding shoe by means including a connecting rod, a'first pin for pivotally casing, two sets of axially spaced radially directed piston sleeves reciprocably mounted in said secondary cylindrical chambers, each of said piston sleeves being formed of an expansible material, whereby limited expansion of the sleeve may be effected upon an increase in the nuid pressure within the piston sleeve so as to decrease fluid leakage between the piston sleeve and inner surface of the secondary cylindrical chamber. a separate shoe for each of said pistons. said shoe being .slidably positioned on\`said eccentric member, said shoe having a iirst recess formed in the outer surface thereof, and said recess having a spherical radius, each of said pistons having a semi-spherical end positioned in the first recess formed in its corresponding shoe for maintaining alignment between said shoe and pistons. a iirst fluid inletlport formed in said member and opening radially from saidmember. second ports extending through each oi said shoes. each ot said shoeshaving formed in the member contacting surface ofsaid shoes a second recess into whichVA V opened and closed to said huid inlet port, and

londary chambers at the other end of each of said spring members for lcoupling said rings together at the opposite sides of said shoes, whereby upon rotation of said eccentric member reciprocable each of said second ports opening into one end of its corresponding piston sleeve, third nuid outlet ports formed in said casing and opening from each of said secondary chambersv at the other end of each of said piston sleeves. a check valve in each of said outlet ports for opening and closing said outlet ports in response to the pressure and suctionforces effected by said piston sleeves, each of -said piston sleeves being coupled to its corresponding shoe by means including a connecting rod, a iirst pin for pivotally connecting one end of said rod to the piston sleeve. a second pin inserted through the'uppite sides of said shoe for pivotally connecting the opposite end of saidrodtosaidshoe: apairofannularrinsspcsitioned at the opposite'ends `of said pin for securing'the same in place and enzlgin! Saldshoe Vat the opposite sides thereof in such a manner as .-of said shoes. whereby upon rotation of said ecmovement may be imparted to said piston sleeves. 75 imparted to said piston sleeves.

centric members reciprocable movement may be erably connected along the peripheral surface of said. abaxial member for reciprocable lmovement. in said secondary chambers upon rotation of said shaft, and said arcual port periodically opening into said main chamber and into said secondary chambers through said piston sleeves upon rotation of said shaft, whereby a uid medium may be drawn through said inletpassage and directed under centrifugal force into said secondary chaml0 bers.

V JAMES E. BEVINS.

escasas y I 7

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