US1978441A - Variable displacement pump - Google Patents

Description

E. J. SVENSON VARIABLE DISPLACEMENT PUMP Filed Oct. 5, 1929 2 Sheets-Sheet l Oct. 30, 1934.

0612.30, 1934. SVENSQN 1,978,441

VARIABLE DI SPLACEMENT PUMP Filed Oct. 5, 1929 2 sh s- Patented ase, 1934 UNITED sures PATENT OFFICE Myinvmtlonreiateagmuallytopmnpeand moreparticularlytotsinplnnpsd thevariabietype.

Ithasherehdorebcmthemacticemmanyinsstancutoemployoil annpsandthelikeincminection with apparatnssneh asmachine tools having hydraulically controlled movable parts. Suchpumpsmustohvhlalyheofthevarlalie dispttypeinordertoeifectthepa per iotunctioningolsaidmachineparts. Itlnshem thepracticeinsomeinstancestoanployahydraulicormmpingmeehanismwhichincludesa highpressurepumpandaseparateorindqimdentlowpreasmemnnpwhhhservestcmpeb' 15 chargethehighpressurepmnp. Dueinthefact mspacewhencomparedwiththesineotthemachines with which they are asociated. Thine conventional devices not only presmt considerablebulkasflieresultoitheuseotindepunimt low and high pres ure units but also present complicated arrangements. These complicated siruetlnal arrangements are dueinparttotheiactthatinorder to efiect variable t from the hill pressure pump,certainotthe annpeiementsmmtbe shiitedtoeifectvariatkminstrokeotthemstma whichare employedtodevehphighpressmein the system; The large size and arrangement of thesepump render the same relatively expensive and hence make their application impracticd for use in machines which, from the standpoint oi manui'acturingcostswillnotwananttheuseofe P21151178 t M611 @5011, mu

, One of theprimaryobjectsolwtmventionistcprovideanoperablepmnping mechanism of improved practical design whichisextremelysimpleinconstmetionand which is very compactly arranged.

More specifically, my invmticn cmtunplates the provision of a pumping mechanisn of unitary construction which is capable of providing low pressures and high in a without the necesity of separate or independent pumping units.

Still more specifically. it is an object of my 'prsent invention to provide a. compactly arranged unitary pumping mvice which is enclosed withinasinglechamber, one portion of the chamberbeingcmnecfibiewithasmrceotiiuid mb. the mu with my the chamber to low pressure and subsequently .to high pressure, said pumping mechanism being adjustable within the chamber. for varying the t thereof in accordance with the needs incident to-its use.

Still another object oi my invention is to provide in a pumping mechanism oi the above mentioned nature, a rotary high pressure device having a centrally located valve whichmay be conveniently shifted for varying the displacement of fluid.

Still another and more specific object of my invention is to provide a compact pumping arrangement in which a pair of gears are employed for subjecting fluid to low pressures, a rotary plunger pump being mounted within one of said gears, the low pressure fluid delivered by said gear pump serving to super-charge said rotary pump, all of said parts being compactly arranged within a relatively small chamber.

Another object of my invention is to provide a hydraulic transmission device of a portable nature and to this end I propose to use a pair of gears forming a pump within a'casing, a rotary plunger pump.'within one of said gears, and a central, non-rotatable valve which forms a bearing for said plunger pump, said valve being supported on opposite sides of said plunger pump in such a manner as to preclude the possibility of distortions which might otherwise result from pressures to which the valve is subjected.

In addition to the above mentioned advantageous characteristics I propose to provide very efi'ectlve means for adiusting the position of the rotary pump within the gear to control the variation in displacement of the pump.

with the foregoing and other objects in view, which will appear in the following description and in accordance with the general features of v the invention, it is to be understood that one embodiment thereof consists generally of a pair of meshing gears mounted within a suitable chamher. One of said gears is mounted upon a shaft which is connectible with a suitable source of power supply and the other gear has a central bore or opening which accommodates a rotary plunger pump which consists of a plurality of pistons radially positioned within a rotor. The gear which houses said rotary pump is mounted independently oi. said pump and rotation oi-said gear causes rotation oi. the rotor carrying said pistons. This rotor is rotatably mounted upon a member which serves as a bearing and a valve. .Fhl d is supplied from a suitable source to said chamber and is compressed through the meshing action of said gears. A portion of this compressed fluid is directed into association with the pistons in the rotor through the central valve and is then compressed to a high pressure and discharged through a passageway in said valve. In order to vary the displacement of the rotary pump I provide eccentric bearings for the valve which may be manually or otherwise controlled from a point externally of the pump unit.

With the foregoing in view, it is to be noted that the invention resides in the novel combination and arrangement of parts and in the details of construction hereinafter described, reference being had to the accompanying drawings, wherein:

Figure 1 is a side elevational view of a hydraulic transmission unit which is representative of one embodiment of my invention Figure 2 is a central vertical transverse sectional view taken substantially along the line 2-2 of Figure 3; V

Figure 3 is a vertical sectional view taken substantially along the line 8--3 of Figure 2 Figure 4 is a fragmentary sectional view taken substantially along the line 44 of Figure 3; and Figure 5 is a fragmentary sectional view taken substantially along the line 5 -5 of Figure 3, said view disclosing the relative positions of the intake and outlet passages which communicate with opposite sides of the meshing gear teeth. Referring now to the drawings more in detail wherein like numerals have been employed to designate similar parts throughout the variousopposite sides of a central frame member or spacer by means ofsuitable bolts 22. The shaft -14 is rotatable within suitable bearings 24 and 26. A plug 28 positioned at one extremityof the shaft 14 co-operates with a stufling-box 30 secured to the bearing 26 in preventing the leakage of fluid at these points.

Referring to Figure 2, it will be observed that chamber sections 32 and 34 are positioned on opposite sides of the meshing teeth of the gears 10 and 12. Fluid, 'as for example oil, may be introduced within the chamber section 32 through a passageway 36, Figures 2 and 5, which communicates at its outer extremity with a supply pipe 38; This supply pipe 38 may be connected to any suitable source of fluid supply (not shown) and fluid from said pipe passes through the passageway 36 into the chamber 32, and rotation of the gears in the direction indicated by thearrow in Figure 2 causes said fluid to be compressed within the chamber section 34. In other ,words, the fluid in the chamber section 34 is the side frame 16 by means of suitable bolts 44.

From the foregoing it will be apparent that fluid introduced withinthe passageway is under a predetermined low pressure. In some instances sure fluid from the passageway 40 and this is accomplished by directing said fluid through a pipe 46 shown in Figures 3 and 5. The portion of the fluid which is not diverted through the pipe 46 passes through a passageway 48 formed within the cover member 42. The opposite extremity of this passageway 48 communicates with a central chamber 50 and from this chamber the low pressure fluid is directed through a passageway 52 which extends longitudinally of a valve member 54.

This valve member 54 is mounted at opposite extremities within suitable discs 56 and 58. The valve member 54 is positioned eccentrically with respect to said discs for effecting the control of fluid displacement as will later be described. The central portion of the valve member 54 presents a bearing section 60 which provides a bearing for a rotor 62.

Slidably mounted and radially positioned within this rotor 62 is a plurality of plungers or pistons 64. The gear 12 is formed with a central bore 66 which is designed to receive the rotor 62 and its reciprocable pistons or plungers 64. The gear 12 is also formed with shoulders or flanges 68 and these flanges are rotatably supported by suitable anti-friction bearings '70 which in turn are centrally supported by annular shoulders 72 formed integral with the end frames 16 and 18. In other words, the gear 12 is rotatably supported by the anti-friction bearings independently of the rotor 62. In the present embodiment of the invention I have shown the gear 12 as being provided with a lug 74, Figure 2, which interlocks with a companion recess 76 within the rotor 62. It will thus be apparent that the rotor'is driven by the gear 12. In certain instances the frictional contact between the outer ends of the pistons 64 and the inner peripheral surface of the gear 12 may be suflicient to cause rotation of the rotor without the necessity of employing an additional interlocking means such as the lug 74.

From the foregoing it will be apparent that when the rotor is eccentrically positioned within 120 the bore or chamber 66 of the gear 12, the low pressure fluid which passes through the longitudinal passageway 52 is directed into a chamber '78 and as the pistons move from the right side of the chamber 78, Figure 2, to the left side thereof, said pistons are moved outwardly so as to effect the intake of the fluid. As said pistons are successively carried in a clockwise direction, the low pressure fluid associated with each piston is carried into a chamber 80 oppositely disposed from the chamber 78, and as these pistons are moved past said chamber the fluid is subjected to a high pressure as the result of the inward stroke imparted to the pistons. This high pressure fluid is directed from the chamber 80 through an elongated passageway 82 which terminates at the outer extremity of the valve 54. From this point suitable piping 84 may be employed to direct the fluid to any desirable point.

In order to vary the displacement of the fluid 140 by the high pressure rotary pump, I provide a pair of pinions 86 which mesh with teeth 88, Figures 1 and 4, formed along a portion of the peripheral surface of each of the discs 56 and 58. Rotation is imparted to the pinions 86 through the agency of a hand wheel 90 mounted upon the outer extremity of a shaft 92 which is detachably secured at its inner extremity to a similar shaft 94. It is to be observed that a wide range it is desirable to divert a portion 01' the low presin variation in displacement may be efiected by emur rotating the hand wheel 90. Obviously the eccentricity of the valve 54 and relative sizes of the co-operating parts may be arranged in accordance with the particular work which is to be accomplished. A cover plate 96 similar to the cover plate 42 is clamped against the outer surface of the side frame 18 by means of suitable bolts 98, said cover member serving as a closure or casing for the pinion 8B and the disc 58. In

order to facilitate the attachment or molmiing of the described pumping mechanism, I provide bracketslOO which are adapted to be secured in position as for example against the side of a machine by means of any suitable devices such as bolts (not shown).

From the foregoing description it will be ap-= parent that my invention contemplates the provision of a pumping mechanism which is of extremely simple yet durable and practical con-- struction. Combining the gear pump and rotary plunger pump in the manner described presents a verycompact construction which reduces the bulk of the device to a minimum and greatly facilitates the ease with which fluid may be conducted between low and high pressure pumping units. One of-the problems which has heretofore been presented in connection with the construction of fluid pumps of the rotary plunger type has been that of counter-acting the pressure set up in the rotary pump to avoid distortion of the pump mounting. In this connection attention is directed to the manner in which I support the valve 54 which serves in the dual capacity of valve and bearing. It will be seen that the valve 54 is RIP-1 ported on opposite sides of the centrally posh tioned rotary pump and thus said valve is prevented from distortions which might otherwise result from the pressures occasioned in response to the operation of the rotary pump if the valve were only supported at one extremity. By having the rotor and its pistons operable in response to the frictional engagement with the inner surface of the gear, I avoid the necessity of employing hereinbefore set forth, I have disclosed a positive or interlocking connection between'the rotor G1 and, the gear 12 but in instances where the diameter permits of the use of relatively long pistons. the frictional engagement of the internal surface of the gear with the pistons may be suflicient to impart rotation without any appreciable smart of slippage. The non-adjustable anti-friction bearings upon which the gear 12 is independently rotatable presents a very practical and inexpensive construction. The construction of my rotor together with the arrangement of the bore in the gear 12, enables me to employ plain solid plungers and this arrangement of the plungers is to be distinguished from complicated plunger supporting devices which have heretofore been employed in connection with rotary pllmger pump. It will also be clear that very little, if any. sliding action takes place between the internal surface of the gear 12 and the outer extremities of the pistons. The only sliding action which might result would be that occasioned by the Ililht eccentric displacement of the rotor with respect to the lute proper alignment. Directing high preaure fluid through piping which is directly connected with the valve reduces to'a minimum the posir l'l lhlewhiehhaaheretofuebeenexpetieneedinhutaneeawherevalveaaresubieeted toextensiveslidingorshiftingaetim. Thisex. i a -h manism quiresapartieulararrangesnmtofpipingfor withdrawingiiuidfromthevalveandtheaedifn. mutiesareentirelyobviatedbythemeofavalve construetedinaeemdancewithmyinvention. In 'mtheflishtlatenlmovementwhieh isimpartedtothevulveslwhm itisdesireil to ehangetheeceentricitythereofissoslightthat' vsuchshiftingniovernentslcanliereairlilytal'enup v ninewhiennmmeteua thevalvewithoutthepotentialhaaardofcauslngleahge.

Attenfionisdireetedtothefacttbatbyemployingthetypeofadiusting'meananlmellthedises Standiswhiehsumrxortthevalvemmberfil amabletolaterallyadjustsaidvalvemember, andeonsequentlytherotorflwithmtdisturbing thetimingoftbevalvewithrespecttothefunctioningofthepistom. Inotherwordathe rotatimofthediscsflandilsuhjectsthevalve 'toatransversemovelnentwhiehlssubstantially linear. Thatistosamtheadjustingactionofthe dlscsshouldbeelearly'distinguishedfromadjustingrnechanismswhichneceaitateshlftingoftbe pumpmechanisminsuehamannerastoseriouslyaitectthetimingofthevalve. Inadjuatiug myvalve,lsubjeetthesametoambstmtially straight transverse movement. and hence-am abletomaintainsaidvalveinpmpertimedrelatiouwithrespeettotherotoe.

Ininstaneeathroughoutthespeeincationand claimswheresuchtermsashmpingmeehanim",gnnnpingdeviee",humpandtheliteare employed itis-tobeunderstoodthattheseterms shmrldnotbelimitedtothepartieulartypeof devieeshovm inthedrawings. Infaet,these terrmareusedtomggestanydevieewhetherit beoftheeompressingor'suctioutypeforconveyingafiuidimedium. l'notherwordatheinventimiisnotlimitedtotheparticulartypeof pmnpingdeviees disclosedwteontemplatesmany othermodiflcationswithoutdepartingfromthem Having thus my invention what I claimaanewanddesretoseeurebyletters Patentb:

LA pumping including a gear pump within a. chamber. a, rotary pump including premure developinl pump elements positionedwithinandsynehronouslydrivenwithone ofthegearsofsaidflrstmentionedmlmmoutlet mea'mf'ordireetingiiuidfromsaidrotarypmnp toapolntexternallyofsaidpnmpingmeehanism. andmeansfordirectingfluidfrosnthe peripheryofatleastmeofthegeanofsaid -georpunnwtoslddroltar'vpump.

1A pumping mechanhm including a gear pump'foreompresingiluid.arotarypumpinclndillpreniredevelmlngpmnpelementapositionedwlthinandaynchronomlydrivmwithme. ofthegears ofnidflratmentionedpumpfor mlijeetingfluidtoepeemnevarrinlfromtheflfl prasum produced by said gear pump. outlet meamfordireetingiiuidifrolnaaidrotarypmnp toapointeatemallyofseidpmnpingmechanislmandiluideondnetlngmeanaeonnectingtho peripheryofatleaatmeotthegearaofsaidgear pnmpforsllijeetingiiuidtoarelativelylnwil'esmmnidpumpinelndingarotarymllnbflna mtlrrplu au-mmphavmep smopvrablellu within and synchronously driven with said'mem-' sure, an outlet for said plunger pump which is independent of said gear pump, and fluid conducting means extending between the periphery of at least one of the gears of said low pressure gear pump and the plungers of said high pressure pump.

4. A pumping mechanism including a gear pump for subjecting fluid to a predetermined pressure, a second pump having pressure developinggpump elements positioned within and driven by one of the gears of said first mentioned pump, said second pump being adapted to subject fluid to a pressure differing from the pressure produced by said first mentioned pump, and fluid conducting means extending between the periphery of at least one of the gears of the gear pump and the intake side of said second pump.

5. A pumping mechanism including a first pumping device for subjecting fluid to a predetermined pressure, said pumping device including a rotary member having an internal cylindrical surface, a rotary plunger pump having plungers engaging the internal cylindrical surface of and driven in synchronism with said rotary member for subjecting fluid from the first pumping device to increased pressure, fluid conduct.-ng means extending between said flrst mentioned pumping device and said rotary plunger pump, and an independent outlet-for said plunger pump.

6. A pumping mechanism including arotat able member having a central chamber, driving means engaging the periphery of said rotatable member for imparting rotation thereto, rotary pumping elements including a rotor and circumferentially spaced reciprocable pistons positionedwithin said rotatable member and adapted to be driven thereby, and a housing providing a mechanical seal for fluid at the point of engagement between the driving means and the periphery of said rotatable member.

7. A pumping mechanism including a housing, a rotary member having a central chamber rotatably mounted within said housing, driving means for peripherally engaging said member and cooperating therewith to provide pumping means for supplying a charging fluid, a valve member extending within the chamber of said rotary member, a pumping device including a rotor and a plurality of reciprocable pistons positioned within said central chamber and mounted upon said valve member, said pumping'device being driven by said rotary member, means for shifting the axis of the rotor with respect to the axis of the rotary member for varying the displacement of fluid, and conducting means for directing fluid'for charging purposes from said pumping means to the pistons of said pumping device.

8. A pumping mechanism including a housing, a rotary member rotatably mounted insaid housing, mechanical driving means for actuating said rotary member, a bearing member extending through said rotary member, a pumping device including a rotor and a plurality. of reciprocable pistons supported by said bearing member for subjecting fluid to increased pressure, a shiftable support having a cylindrical. bearing surface for receiving and encircling-said bearing member on each side .of said pumpng device, and means for shifting said support to thereby laterally her for varying the displacement of fluid, said shiftable support providing a mechanical seal at the peripheral surface of the bearing member to prevent the escape of fluid from within the housing.

9. A pumping mechanism including a housing, a rotary member having a central chamber rotatably mounted within said housing, a bearing member extending into said central chamber, a pumping device including a rotor and a plurality of reciprocable pistons therein supported by said bearing member within said central chamber, a rotatable adjusting means positioned eccentrically with respect to and surrounding said bearing membenmeans for rotating said adjusting means for shifting the position of said hearing with respect to the axis of the central chamber, and driving means for said rotary member and cooperating therewith to form a pumping couple for charging the pistons of said pumping device.

10. A pumping mechanism including a housing, a rotary member having a central chamber rotatably mounted within said housing, means for rotating said member and cooperating therewith to provide a piston charging means, a bearing member extending through said central chamber, a pumping device supported by said bearing including a rotor and a plurality of pistons reciprocable therein; a rotatable adjusting means positioned on each side of said pumping device, the axes of said rotatable means being positioned eccentrically with respect to the axis of the bearing, means for imparting movement to said rotatable adjusting means for shifting the pumping device within the central chamber, and fluid conducting means for directing fluid from said charging means to said pistons.

11. A pumping mechanism including a housing having a chamber therein, a gear pump mounted within said chamber, one of the gears of said pump being connectible with an external source of power supply and the other of said gears having a central chamber, a bearing extending within said central chamber, a pumping device including a rotor and a plurality of reciprocable pistons'supported by said bearing within said central chamber, and means for directing fluid from said gear pump to the pumping device within said central chamber.

12. A pumping mechanism including a housing having a chamber, a gear pump mounted within said chamber, one of the .gears of said pump having a central chamber, a mounting for said last mentioned-gear, a rotor and a plurality 13 of pistons carried thereby positioned within said central chamber and constructed and arranged to be rotated in synchronism with said last mentionedgear, a bearing for said rotor which is independent of the mounting for said chambered 5 gear, fluid conducting means extending between .said gear pump and said rotor, and driving means for one of saidpumps connectible with a source of power supply.

13. A pumping mechanism including a housing having a'chamber, a gear pump mounted within said chamber, one of the gears of said pump being provided with a central chamber, a bearing extending within said central chamber, a rotary pumping device mounted on said bearing including a rotor and a plurality of reciprocable pistons, means for shifting said bearing with respect to the axis of said chambered gear to vary the displacement of fluid, means for directing fluid from said gear pump to said rotary pumping device, and driving means one or said pumps connectible with a source of power 14. A pumping mechanism including a housing having a chamber, a'gear pump including a pair of meshing gears mounted within said chamber, one 0! said gears being connectible with a suitable source of power supply and the other of said gears .having a central chamber formed therein, an anti-irictionmounting for said chambered gear, a valve member extending through said central chamber, a rotary pumping device mounted upon said chamber member and including a rotor and a plurality of reciprocable pisls tons, said pistons being Irlctlonally engageabie at their outer ends with the internal surface oi said chambered gear, a bearing'ior said valve member positioned on opposite sides of said rotary.

pumping mechanism, and fluid conducting pasgo sageways within said valve member.

15. A pumping mechanism including a housing having a chamber, a gear pump including a pair 01 meshing gears mounted within said chamber, one of said gears being connectible with a suitable source or power supply and the other of said gears being provided with a central chamher, said chambered gear being rotatably mounted within said housing, a valve member extending within said central chamber, a rotary pumpso ing'device mounted on said valve member including a rotor and a plurality oi reciprocable pistons, means for shitting said valve member with respect to the axis of the chambered gear, and fluid conducting passages in said valve mem-' her. Y

18. A pumping mechanism including a housing, a rotor within said housing, a plurality of reciprocable pistons in said rotor, said pistons being of the plain type without attachments at 40 either end thereof, rotary means movable in synchronism with said rotor for imparting movement to said pistons, a central valve member extendingwithin and supporting the rotor, driving means peripherally engaging said rotary means and cooperating therewith to form a pumping couple for supplying a charging fluid, and conducting means for directing fluid from said charging means to said pistons.

1'1. A pumping mechanism including a housing,

a rotary piston driving member within said housing having a central chamber, means for actuating said rotary member, a valve member extending within said central chamber, a 'rotor mounted on said valve, a plurality of plain cylindrical pistons reciprocably mounted within said rotor, the outer extremity of each 0! said pistons adapted to directly engage the internal surface of said chambered rotary driving member. and the inner extremity of each of said pistons being free from supporting attachments, driving means peripherally engaging said rotary driving member and cooperating therewith to provide a pumping couple for supplying a charging fluid,

' gearsof said gear pump.

'20. A pump construction including a gear pump for delivering fluid under charging pressure, a plunger pump coupled therewith, said plunger pump including a plurality of radially disposed pistons within a support and a valve .centrally disposed with respect to said radial pistons for controlling the 'delivery of fluid toward I and away from said pistons, said plunger pump valve being arranged in substantial parallelism with and positioned within one of the gears of the gear pump, and means for directing charging fluid from the gear pump'to said plunger pump.-

21. A pump construction including a gear pump Y for delivering fluid under charging pressure, a plunger pump coupled therewith and driven by oneoi' the gears of said gear pump, said plunger pump including a plurality of radial reciprocable pistons within a support and a central valveoi cylindrical cross'section positioned centrally with respect to said pistons and support for directing fluid toward and away fromsaid pistons, the axis of said valve being substantially co-incidentwith the piston support and located with one of the gears or said gear pump, and means for directing charging fluid from said gear pump to said plunger pump. 22. In a fluid propelling mechanism, supporting means, a plurality of radial reciprocable pistons therein for receiving fluid under a given pressure and discharging said fluid under increased pressure, a charging pump including rotary pump elements positioned adjacent said piston supporting means, one ofthe rotary elements of the charging pump providing a driving element for said plunger pump, a valve having an axis centrally disposed with respect to the reciprocable pistons-for controlling the flow of fluid toward and away from said pistons and positioned in substantial parallelism with and in the vicinity of the axis of one of the rotary elements oi! said charging pump, rotary means for effecting relative movement between the valve and piston supporting means along a substantially straight line whereby to 139 ment being such as to present a sch-contained 3' compact plunger pump and charging pump construction.

23. A pump construction including a charging pump having a rotary element, a plunger pump including a plurality of radially disposed pistons no reciprocable within a sup rt, said plunger pump being driven by and having the axis about which the pistons radiate disposed in substantial parallelism with respect to and inthe' vicinity otthe axis of the rotary element in said charging pump,

a valve for timingly controlling the flow o! fluid toward and away from said plunger pump, means for directing charging fluid lrcm said charging pump to said valve, and means for causing relathe substantially linear movemen between the valve and piston support for efiecting a variation in the stroke of said pistons without disturbing the.

timing of the valve with respect thereto.

24. A pump construction including a charging pump having a rotary element, a plunger pump including a plurality of radially disposed pistons reciprocable within a support, said plunger pump being driven by and having the axis about which the pistons radiate disposed in substantial parallelism with respect to and in the vicinity of the axis of the rotary element in said charging pump, a valve for timingly controlling the flow of fluid toward and away from said plunger pump, means for directing charging fluid from said charging pump to said valve, and rotary means for imparting a substantial linear transverse movement to the valve for effecting variation in stroke of said pistons without disturbing the timing of said valve with respect to said pistons.

25. A pumping mechanism including a housing having a chamber therein, a gear pump mounted within said chamber, one of the gears of said pump being connectible with an external source of power supply and one of said gears having a central chamber, a bearing device extending within said central chamber, a pumping mechanism in said chamber and driven in synchronism sure, said pumping mechanism including a plurality of reciprocable pistons, and means for directing fluid from the peripheral surface of said gear pump to the pistons of said pumping mechamsm.

26. A pumping mechanism including a housing. a pair of meshing gears mounted withinsaid housing for subjecting fluid to a required pressure, inlet and outlet chambers associated with said gears, one of said gears being connectible with an external source of power supply, a plunger pump positioned within and having its plungers operatively engaging one of said gears, said plunger pump including a rotor and a plurality of reciprocable pistons within said rotor and capable of subjecting the fluid from said gears to increased pressure, and means for directing charging fluid from thegears to said plunger p p.

27. A pumping construction including a piston support, a plurality of radially disposed pistons in said support, a valve of circular cross section positioned in substantial parallelism with the axis about which the pump pistons radiate for controlling the delivery and discharge of fluid to and from said pistons, a housing, and a plunger pump actuating means in said housing including a driving gear provided with a central chamber and having its axis positioned in substantial parallelism with respect to the axis about which the pistons radiate, said support and radial pistons being housed within the central chamber of said driving gear, the elements of said plunger pump actuating means cooperating to provide a pumping couple for supplying charging fluid to said plunger pump, and conducting means hydraulically connecting said pumping couple with the pistons of said plunger pump.

28. A pumping mechanism including a gear pump comprising a pair of meshing gears and a housing therefor, a rotary pump having pressure developing pump elements thereof mounted within one of the gears of said gear pump, fluid conducting means connecting the peripheral surface 01 at least one of the gears of said gear pump in series with said rotary pump, and inde pendent fluid conducting means for directing fluid away from said rotary pump.

29. A pumping mechanism including a gear pump within a chamber, a rotary pump having pressure developing pump elements thereof within and actuated by one of the gears of said flrst mentioned pump, outlet means for directing fluid from said rotary pump to a point externally of said pumping mechanism, means for directing fluid from the periphery of at least one of the gears of said gear pump to said rotary pump, and mechanical means forpositively connecting the rotary pump with the gear within which said rotary pump is positioned.

30. A pumping mechanism including a housing, a rotary member having a central opening and rotatably mounted within said housing, driving means peripherally engaging said rotary member, a piston support, a plurality of radial pistons reciprocably mounted within said support, and a valve member having its axis in substantial parallelism with the axis about which said pistons radiate for controlling the passage of fluid toward and away from said pistons, the axis of said rotary driving means being substantially parallel with the axis about which said pistons radiate, said housing engaging the sides of said rotary member to provide a mechanical seal at the point where said rotary member is peripherally engaged by said driving means to prevent the escape of fluid from within the housing.

31. A pumping mechanism including a piston support, a plurality of radial pistons reciprocably mounted within said support, said pistons being of the plain cylindrical type free from attachments at either end thereof, a valve member positioned centrally with respect to said pistons for controlling the flow of fluid toward and away from said pistons, and piston actuating means including a toothed driving gear provided with a central chamber and having its axis substantially coincident with the axis about which the pistons radiate, said pistons being housed within the chamber of said driving gear.

32. A pumping mechanism including a hous- 1 8, a rotary member provided with a plurality of chambers therein, pistons movable in said chambers, inlet and outlet ports in said housing, a pintle and valve member adapted-t0 eccentrically support said rotary member in said housing and connecting said ports with said chambers, a rotatable member on each side of said rotary member providing a mounting for said pintle and I valve member and surrounding and engaging said valve member with a sealing fit to prevent escape of fluid from within said housing along the peripheral surface of said pintle and valve member, said rotatable supporting member being rotatable to vary the eccentricity of said rotary member whereby the capacity of the pump may be varied. o

33. A pumping mechanism including a housing, a rotary member provided with a plurality of chambers therein, pistons movable in said chambers, inletand outlet ports in said housing, a pintle and valve member adapted to eccentrically support said rotary member in said housing and connecting said ports with said chambers, a rotatable disc member on each side of said rotary member providing a mounting for said pintle and valve member and surrounding and engaging the peripheral surface of said pintle and valve member, said rotatable disc member being rotatable to vary the eccentricity of said rotary member whereby the capacity of the. pump may be varied.

34. A pump construction including a gear pump comprising a pair of mesh gears, a plunger pump adapted to be charged by. said gear pump, at least one of the gears of said gear pump having a central chamber and constituting a driving mechanism for the plunger pump, said plunger pump'including a support, a plurality of reciprocable pistons in said support and a valve member centrally disposed with respect to said pistons, said plunger pump elements being positioned within the chamber of the gear of said gear pump, and fluid conducting means for directing fluid from said gear pump to the pistons of said plunger pump for charging purposes.

35. A pump construction including a gear pump for delivering fluid under a charging pressure, a plunger pump adapted to be charged by said gear pump, one of the gears of said gear pump having a central chamber and operatively connected with said plunger pump for the purpose of driving said plunger pump, said plunger pump including a rotor and a plurality of reciprocable:

pistons carried within said rotor, said plunger pump elements being housed within the central chamber of the gear of said gearypump, said rotor being adapted to be eccentrically positioned with respect to said chambered gear, and'fluid conducting means for directing charging fluid from said gear pump to said plunger pump.

36. A pumping mechanism including a pair of gears, one gear being capable of driving the other, and a rotary pump housed within one of said gears comprising a rotor having a plurality of circumferentially spaced pistons carried thereby and adapted to receive fiuidat' one extremity thereof from the'peripheral surface of at least one of the gears of said-pair.

37.,A pumping mechanism including a pair of gears, one gear being capable of driving the other, a rotary pump housed within one of said gears comprising a rotor having a plurality of circumferentially spaced pistons carried thereby and adapted to receive fluid at one extremity thereof from the peripheral surface of at least one of the gears of said pair, and valve means for controlling the flow of fluid toward and away from said pistons. ERNEST J. SVENSON.

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