US2695566A - Pump, bushing graduated pressure responsive areas - Google Patents

Description

Nov. 30, 1954 J, COMPTON 2,695,566

PUMP BUSHING GRADUATED PRESSURE RESPQNSIVE AREAS 2 Shee'tsSheet 1 Filed May 19, 1950 United States Patent Ofifice 2,695,566 Patented Nov. 30, 1954 PUMP, BUSHING GRADUATED E PQ W EA James A. Compton, South Euclid, Ohio,

PRESSURE si s? t B r "Warner Qorperafi on, lCliicagotyIlL, afcorporatihnh of This application is a continuation-in-part of the copending original application of- James A; Compton for Pump with Pressure Loaded Bearings,tiled-December 14,1949 Serial No. 13;;934. i

This invention relates to a pressure loaded pump, and more particularly toa pressure loadablehushing-for such a pump having a graduated pressure responsive motive :H ,i' ...1 11. I i. 1J5. .2! ,As is well knowm in a pressure loaded pump apart of the discharge'pressure is" applied: to fthdrear or-"motive surfaces of 'the axially movable pressure-loadablebusha51 ,:bu h l si h da' t l vf f up; aree'mployed as m a gea'r pumptto lirge he;;bush

sealing engagement withi the associated; pumping e em sclcised iiiU. S -Patent l lo. 2,420,62-2to RfothetaL, by carefully selecting the" relative "a'reas 'of "the forward we surfacesl of surfaces of th e' busjhings and of ithe mo 7 abi hi i n 'i msshifi iseartir rum p ":sible to control fwithin Waryyclose lirnits the ac al 'se alfling pressure provided. In practica thisfrelq "res What higherforce' inthe clirection'jof se direction of tending to-op e'n theseal.

* In'the' type; of pressure loaded pump des cribed in the above patent; the; motivef-or loadiiig'fchamber to"which discharge pressure "is supplied willfbefunifoifmly eubf j'ectedfto the discharge pressureJ-fThatf-istosay, at" all points on the motive surfaces; at the rear of the bushing, "substantially the same pressure will exist: Therefore, where, as in a conventional}intermeshifiggearftype p'resthe motive" surface; comprises an "an- "l u fl 'pi p;

nulds cencentrically disposed :with "frespct to the xis of the pumping gear, the'loading forcefis-uniform about 'the axis of thepumpi' 'the otlier' haridg jthefor hard surrace of.thebushing, "thatis, thesurface adjacent .the "pumping elementflside surface,"while uniformly disposed with respectto the axis of-thef bushingfisflnot subjected j to a uniform fiuidhp'ressure 'S ince-Lthe'pressufe across "the fcrwai'd surfaces of. the bushing extnds fr'ornifthe fminimum value corresponding to inlet'pressurefin'the rea adjacent the iriletofithe pump tda" rn'aximul" resmmmg to discharge pressure" adjace'nfithe of the pump, the pressure a cr'oss the gear side'f ce erigaging'surface grad l lyjin easesffrom' inlet to 'echarge "f'pressure". i ly; will be evident thaf'tvliil'efthe jtotal pres'surefdrc'es acting on themotiveor loading 'jSIll'f iCCS qt thebushing may be'nrade to "equalor' to exceed the total pressure forcesfacting on the forward surfaces "of the bushing, the pressures acting on alloppositepoints 1 of the twobushing surfaces Willn'ot beso proportioned and the portion of the forward bushing. s face nearer the inletbe'ing subjected to a le ser pressureftending to break the seal"than theponie cameraman; bushing "surface nearer the joutlet' of th Ph l p, an unbalanced pressure conditionresults', tendi 'g" to twist'the" bushing in the pump housingand prbdueingjuneven'wear; .Wear

is, of course, concentrated onthe. inlefsidefof'the pump. As'set forth in them-pending application dfFrederick C: Haberland, SJNL 130,904,'filed peeember 3,?1949, the unbalanced condition resultingffr m' the' pressure gradient acting across the forward surface of the" biish'ing may be {compensated by offsetting the pressureresponsive 'tnotive surface of the bushing so that a les'ser"a'reat5f"the motive surface is exposedon' the 'inletside'of'the pump than on 'the discharge'side. "This "is' accomplished "by "employing a bushing having a flanged end ai'iaptedto engage: the pumping :elment .side surface and: offsetting the periphery of the barrel portion in the direction of the 'inl'et side of thepump. The resultant, generally annular, motive surface area inlet *side' of the has a markedly less width adjacent the pump than adjacent' the *outlt side. Therefore, since the force exerted-is a fun'ction of'thepresproportionately greater force 1 is exerted on the discharge side of the motive surface thanon th'e 'inle'tside", thus compensating'for the pressure gradient across the forward surface of theb ushing. The arrangement clescribedin the above-mentioned Haber land application requires a special pump-housing,

found in practice that it is somewhatdifliculttoachieve ii1"production' the "considerable degree of eccentricityiequired without unduly increasing the cost t'urei Furthermore, Haberla11d arrangement is not "constructed. Furthermore, in some cases, it is desirable "'tooperate pumps at relatively high'inlet pressures.- For example, in some tandem pump applications, the inlet hundred'pounds' per square inch less than the discharge pressure of the second pump and may be as highas a -thousand pounds per pressure to the second pump may not be more than affew square inch or more. It will be apparentthat in such application, for optimum operation it is not feasible to disregard inlet pressure, but rather that provision must be made not only for balancing the loading pressure to compensate for thedischargepres- "one set of axially movable,

sure'gradient but also to take into account the'elf'ect on this gradient of relatively high inlet pressure.

An object of the present invention is to provide a new and improved pressure loaded pump, and .moreparticularly, a"pressure loadable bushing assemblyadapted fdr incorporation in a conventional pump housing without modification of the housing" and which bushing assembly will 1 provide a first graduatedpressure responsive motivesur- "face to which discharge pressure is graduated pressure responsive motive surface to fwhich applied and a second inlet pressure is applied.

In accordance with one embodiment of this invention,

a pressure loaded type intermeshing gear pump having 7 pressure loadable bushings may be provided wherein the axially movable bushings each comprise an axially apertured, two-piece bushing as- *vid'ed with a deep, V p p offset with respect to the axial aperture extending through "the cover element in the direction of the the second element of the assembly, plurality of axially spaced, radially extending flanges and s'emb'ly. The bushing assembly includes a cover element, the forward surface of which is adapted to engage the side which provides the of the bushing-ass'embly. The rear surface of the cover element is'procylindrical recess, the axis of which is V inlet side of the pump. The barrel portion of the bushing,--eomprising is provided with a I has an offset, cylindrical, raisedportion or boss on its ""'fo1'ward surface adapted to be received in the recess formed in the cover and to be sealed thereto by aseal'ing ringdisposed in a groove formed about'the periphery of the raised portion.

The sealing ringfthus separates and defines two eccentrically disposed areas, and the area having its larger surface adjacent the inlet side of the pump is placed in communication with pump inlet pressure-by a suitable venting aperture, while the area having'its larger portion adjacent the discharge side of the pump is placed in communication with discharge pressure by a suitable passage. The axial thickness of the assembly from'the forward surface of the cover to the rearmost flanged-surface is e of the flange provided on a conventional pressure loadable f bushingfi The assembly is, therefore,

selected to be equivalent to the normal thickness interchangeable ".with the conventional bushing without modification of the housing. Other objects and advantages of the present invention r the pumping Fig. l, a deep,

will be apparent from the following detailed description taken in conjunction with the drawings wherein:

Fig. l is a fragmentary, axial, sectional view of a pressure loadable intermeshing gear type pump having a pair of bushing assemblies in accordance with this invention;

Fig. 2 is a transverse, sectional view taken substantially along the line 22 of Fig. 1;

Fig. 3 is a sectional view line 3-3 of Fig. 2;

Fig. 4 is a view similar to Fig. 1, showing however, a modification of the bushing assembly; and

Fig. 5 is a sectional view taken substantially along the line 55 of Fig. 4.

Referring now to the drawings, and particularly to Fig. 1 thereof, a pump similar to that shown in the aforementioned Roth et al. patent except for the bushing arrangement is there illustrated having a sectional housing comprising a main body portion 5 and a left closure member 6. These sections are securely bolted together and cooperate to define a pair of parallel axis, intersecting bores or pumping gear chambers 7 and 8 which are artaken substantially along the ranged to receive in complementary relationship intermeshing pumping gears 9 and 10 rotatably journalled in suitable bushing members. In the embodiment illustrated,

gears 9 and 10 have integrally formed therewith hollow journal shafts 11 and 12, respectively, and the right portions of the journal shafts 11 and 12 are received in conventional, flanged bushings 13 and 14 mounted in the right portions of the gear chambers 7 and 8. The left portions of the gear journals 11 and 12 are received, respectively, in axially adjustable, pressure loadable bushing assemblies 15 and 16 mounted in the left sides of the pumping gear chambers 7 and 8. Bushing assemblies 15 and 16 are constructed in accordance with the present invention and will be described in detail hereinafter. In the embodiment illustrated, the lower pumping gear 10 is the driving gear and, accordingly, the left end of gear journal 12 has formed thereon a splined coupling termination 17 whereby the shaft may be drivingly connected to a suitable power source. Low pressure liquid is introduced into the pump housing at inlet 18 and high pressure liquid is discharged through outlet 19, the inlet and outlet passages communicating, respectively, with the inlet and discharge of the intermeshing pumping gears.

As the identical, only the bushing assembly 15 will be described in detail. The bushing assembly 15 comprises a barrel or body portion 22 and a cover member 23 mounted in overlapping relation on the right end of the barrel portion, as viewed in Fig. 1. Cover member 23 is of generally cylindrical or disc-like configuration and has formed therethrough an axially extending aperture 24 of sufficient diameter to receive gear journal shaft 11. In practice, the diameter of the aperture 24 is made slightly greater than the peripheral diameter of the shaft 11 to permit slight angular adjustment of the cover member with respect to the axis of the shaft to accommodate for misalignment, as explained in detail in my application S. N. 28,646, filed May 22, 2948, now United States Patent No. 2,527,941. A short, downwardly extending groove 23a is formed in the lower side of the gear side face engaging surface of cover 23 slightly to the left, as viewed in Fig. 2,

of the transition point of the gear teeth so that this groove is in communication with inlet pressure.

As may be best seen in Figs. 2 and 3, the cover member 23 has formed in the left side thereof, as viewed in cylindrical recess 25, the axis of which is offset with respect to the axis of aperture 24. be apparent hereinafter, the extent to which the recess 25 is offset depends on the gradient to be compensated. The recess 25 is offset to the left, as viewed in Fig. 2, thus reducing the width of the pressure loadable motive surface designated 26 on the side thereof adjacent the inlet 18 of the pump, but correspondingly increasing the width of the motive surface 26 on the side thereof adjacent the discharge outlet 19 of the pump. Cover 23 fits closely the inner diameter of chamber 7 formed in the pump housing, sufiicient clearance, however, being provided to permit axial movement of the cover member with respect to the housing to permit the forward surface of the cover to engage the associated pumping gear side surface in sealing relation.

bushing assemblies 15 and 16 are essentially a As will The barrel portion 22 of the bushing assembly is provided with an axially extending aperture 27 communicating at its right end with the aperture 24 formed in cover 23; however, the inner diameter of aperture 27 may be made somewhat less than the inner diameter of aperture 24 since it is desirable that the shaft 11 be journalled therein with a close, running fit. An axial groove 28 extending from the right to left ends of this wall of axial aperture 27 in the barrel portion 22 ensures suitable lubrication of the gear shaft 11, spiral grooves 29 also formed in the side wall of aperture 27 and communicating with groove 28 facilitating distribution of fluid about the gear journal. It is not essential that groove 28 extend completely to the rear end of the aperture 27, but it may be terminated slightly before this point where desired. Near its left end, as viewed in Fig. l, the barrel member 22 is provided with a deep, annular groove 30 which extends about its periphery and provides at its left side a flange 31 and at its right side a flange 32. The groove 30 is made as deep as possible without unduly weakening the bushing structure to reduce the weight of the assembly and at the same time to expose a greater surface area of the assembly to the fluid being pumped, thereby aiding in maintaining the bushing at a low temperature.

The flange 32 extends radially outwardly substantially further than the flange 31 and its extended portion seats at its left side, as viewed in Fig. 1, on an annular shoulder 33 of the pump housing bore. The body or barrel portion of the assembly is thus securely supported in the pump housing bushing receiving cavity 7 and is relatively immovable with respect thereto in the normal operation of the pump. The right end surface of the large flange 32, as viewed in Fig. 1, has formed thereon a raised or protuberant portion or boss 34 which is received in the offset recess 25 formed in the cover member 23, the boss 34 being offset in similar manner. The boss 34 is complementary to and fits closely into the recess 25 in telescopic relation. Escape of pressure fluid from the surface 26 through such space as may be allowed between the sides of the boss 34 and the adjacent sides of the recess 25 to permit axial movement of the cover 23 is prevented by an O-ring seal 35 disposed in an annular recess 36 formed about the periphery of the boss 34. The O-ring seal permits relative axial movement of the cover 23 with respect to the barrel and particularly with respect to the boss 34 while maintaining a fluid tight seal. The boss could, of course, be provided on the cover 23 and the recess in the end of the barrel 22, where desired, and similarly the seal ring 35 could be carried in an internal groove formed in the recess as well as by the boss 34.

In order to provide initial loading pressure, a plurality of loading springs 37 are disposed in. suitable recesses formed in the boss 34 and the cover element 23 to initially urge the cover element toward the adjacent side surface of the pumping gear 9. This provides the initial sealing engagement required. Immediately, however, upon pumping commencing, discharge pressure is communicated to the motive surface 26 of the bushing assembly through an axially extending passage 38 formed between the bushing assemblies 15 and 16 at the point of convergence of the peripheries'of the large flanges of the two bushing assemblies on their right side, as viewed in Fig. 2, that is, the side adjacent the discharge passage 19 and the adjacent housing wall. This discharge pressure being communicated to the motive surface 26 pressure loads the cover element and urges the cover element 23 to the right, as viewed in Fig. 1, to establish and maintain sealing engagement thereof with the gear side face in accordance with usual pressure loaded pump practice.

It will be understood that either sufficient clearance must be provided between the periphery of flange 31 and the adjacent walls of the pump housing or a suitable passage otherwise formed across the periphery of the flange to vent the chamber defined primarily by groove 30 to low pressure. In the absence of such venting, pressure would accumulate against the left surface of flange 32 as viewed in Fig. 1, causing movement of the body portion 22 of the bushing assembly. Since it is desirable that the flange 31 cooperate with the flange 32 to establish and maintain alignment of the bushing in the bore, preferably an axially extending groove 31a is formed in the periphery of each flange 31, the left end of each groove 31-11 being then in communication with a low or intermediate, pressure zone of the pump through the axially extending passage in the tassociatedgear journal,asdescribed in detail in the afore- -mentionedpatentito Roth et a1.

-area adjacent the inlet side of .the pump, 18 .quite narrow w extent, as is readily evident from Fig. 2,. as compared -to the portion of the motive area adjacent: the outlet. side of the pump, it-will, be evident. that the force.. acting in' the direction of establishing asealnwill be lesson .the

pump inlet sideof the bushingcoyermember, than on the pump discharge side thereof. Thevalue of this pressure loading =force will increase. from .a minimum value adjacent the pump inlet side-of-motive surface 26 to a --maximum value adjacent thepump discharge. side of the motive surface. The-pressure loading forcegradient can *be made by-controlling the ,relative areasof the portion adjacent the inletand of the portions adjacent the outlet a'crossthe motive surface-to correspond substantially in gradient to the-pressure forces effective across the forward orgear-side face engaging surfaces of the cover. At the 1 same time the total extent ofthe area 26 is selected so that thepressure loading force exceeds the oppositely directed force on the gear side face engaging surface of the cover element to provide the netsealing forcerequired to establish anadequate pumping seal in accordancewith usual pressure loaded pump practice.

i It has been found in practice that it is somet mes necessary, in order. to establish the optimum balance, to provide a beveled area 39 extendingpartiall-y around the periphery of the forward surface of the cover element on the side {thereof adjacent-the outlet 19. The beveled area extends in a counterclockwise direction from the discharge side 'of the pump toward the inlet side, as. viewed in Fig. 2,

-andthe location of the left terminus of the beveled area is selected to place this end of the beveled area in commun cation with a zone of relatively low pressure. In add1- tion, the forward or gear side faceengaging surface of the cover 23 may be grooved or relieved and the grooved or relieved areas vented to inlet-pressure as through grooves 23-a to reduce the effective pressure area on this surface, as set forth in the hereinbefore referredto Roth et al. patent.

It will be evident that sincethe eccentric area at the.

- baseof recess 25 is vented to, inlet pressure throughaperture 24 and groove 23a, any pressure fluid from the discharge side of thepump leaking past the seal 35.w1ll be vented to inlet pressure. At the same time, inlet pressure will be effective on this recessed area to urge this side of the bushing cover against the adjacent gear side face with a force proportional to the inlet pressure.

r In someplural unit, tandem pump applications it is the practice to increase the discharge pressure in the laststage {only slightly beyond the inlet pressure to the last stage. Accordingly, the inlet pressure may be a substantial factor in determining the nature of the pressure gradient extending across the gear side face engaging surface of the bushing. From the foregoing description, 1t Wlll be evident that the pump arrangement shown in Fig. 1 wherein inlet pressure is communicated to the base of recess 25 through radial groove 23-a and aperture 24, takes into account inlet pressure. The base of recess 25 being offset in the direction of the inlet side of the pump, conversely to the primary motive surface 26, will in response to application of inlet pressure apply a corresponding force to the cover 23 tending to press it against the gear portions adjacent the inlet.

However, it will also be evident that ,the area of the base of recess 25 is complementary to the area 26, and that increasing one correspondingly reduces the other, and therefore the range of selection of one area is definitely limited by the effect of such selectlon on the other area.

; Referring now to Figs. 4 and 5, a modified form of bushing assembly is there illustrated particularly designed.

for use with pumps to which arelativelyhigh inlet. pressure is supplied. This modified form .permits control of -the extent of the area exposed to inlet pressure independently of the control of the motive surface area exposed to discharge pressure.

As the arrangement shown LH-FlgS. 4 and differs from that illustrated in Figs. 1, 2 and 3 only with respect to the bushing assembly, likereference numerals have been applie i t the r cr e nq d ne parts in'Figs. 4 and 5 and in Figs. 1, 2 and 3, except for the bushing assembly.

. cover 43, when th tion of the fluid. As

. first sealing ring 55 carried ibct li l m The m difiedwb sh member 41 and a barre p y telescopic relation similarly to the bushing assen '13; 15 ,C ov'er member-41 is of generally. cylindrical configuration and has formed therethrough an axially. ex ding aperture. 43; of slightly. greater diameter than the outside ,diameter of the, associated gear journal shaft; Qoverj'41 .fits closely within the inner diameter of thechamber' 7 ,formed in the pump housing, suflicientclearance being ip i to per itax m v en of t ptwe tm mb w h e pect t hehqu dtq pe m lha f ward face ofrhe cov r eng e e Pu p se rsida ur'fia in sealing relation.

Instead of a single, eccentrically dis asthat shown in Fig. ttive y, un qu l s z 41,,the. recess 44 bein scss t e esssus o rece .4 endfii respe are formed in the cover member g offset. to the left, sirriilarly to recess 25of Fig. 2, an d .the recess 45 beingcentered with respect to the bushing. r The larger recessf44.extends to the right from tthe left side of the cover memberfil as viewed in Fig. 4,to a plane spaced approximately onethird the thickness of the cover member fiomjheQleft side thereof; that is to say, the depth of recess, 44 is ap- 1 proximately one third the thickness of then cover rnem- .ber' 41. The second and substantially smaller recess 45, .,which is disposed concentrically with respect to the axis of the bushing assembly, extends to the right frorrifthe base, of recess 44 tofa plane spaced slightly} from, the right side of the covermember, 41, and. is thus of approximately the samedepth as the reces s 44,

L Recess;44 is offset to the left, as viewed in Fig. 5, to recluce the width ofthe annular pressure loadable motive surface designated 46 on the side thereof .adjacent the inlet of, thepump, but to correspondingly increase-,the width of the motive surfaceAtSon the sidethereof adjac,ent thedischarge outlet of the pump. Theextent; to which recess 44 is offset is determined by considerations ,identical with those in connection with recess 25.

The, barrel portion 42 of theb ushing assembly, 40 is provided with an axially extending aperture 47 communicating at its right end with the aperture 43 formed in the e barrel is assembledwiththe cover,

and at its left end with the left end of the upper housing bore. The gear journal is received in the aperture 47 and the inner diameter of aperture 47 is made somewhat less than the inner diameter of aperture 43 since it is desirable that the journal fit therein with a close running An axial groove 48 extending from the right tofthe left ends of aperture 47 insures suitable lubrication of the gear shaft while spiral grooves 49 facilitate distribuwith the groove 28, it is notalways necessary that groove 48 extend the full length of the bushing barrel to the left, and it may be terminated somewhat short at the left end of the bushing, as viewed in Fig. 4. The left end portion of the barrel 42 is substantially reduced to provide a small outer diameter terminal portion 50 received within a correspondingly small diameter portion 7-a of the chamber or bore 7. The left side of the larger portion of the barrel 42, designated 51 in Fig, 4, seats at itsleft side on an annular shoulder 52 of the pump housing bore. The body or barrel por tion of the bushing assembly 4%) is thus securely supported in the pump housing cavity and is relatively immovable with respect thereto in the normal operation of the pump.

Theright end of the barrel member 42 has formed thereon a first raised or protuberant portion or boss 53 which is received in the larger recess 44 formed in the cover. This boss is eccentrically located with respect to the axis of the bushing, being offset in the same manner and to the same extent as recess 44 although of slightly .less outer dimension. A second boss or protuberant portion 54 is formed on the boss 53 and this boss is disposed concentrically of the barrel member 42, in a manner similar to the recess 45 formed in cover member 41. -The boss 54 is received in the concentrically disposed recess 45 in the cover member 41.

In order to isolate the eccentrically disposed base area of the recess 44 from the motive surface area 46 and to place the same in communication only with inlet pressure, a plurality of sealing rings are employed. Thus, a

in an annular recess 56 formed about the periphery of shouldered portion 53 seals against the side wall of recess 44 while a second seal ring 57 carried in a recess 58 formed about the periphery of the boss 54 seals against the side wall of concentric recess 45. Itwill be understood, of course, that the annular recesses may be formed in the walls of the recesses 44 and 45 without departing from the invention.

Referring to Fig. 5, it will be seen that a passage 60 is drilled through the cover, 41, the passage being located so that one end is in communication with the inlet side of the pump and the other end is in communication with the isolated area between the two seal rings, that is, the eccentrically disposed base of recess 44. At the same time, it will be noted from Fig. 4 that the radially extending, short passages 23a provided in Fig. 1 have been omitted. Pumping pressure or discharge pressure leaking past the seal 55 will escape through the passage 60. However, the primary purpose of providing passage 60 is to communicate inlet pressure to the annular area provided at the base of recess 44. Accumulation of pressure against the surface designated 51 in Fig. 4, which might tend to cause movement of the barrel portion, is prevented by either providing a slight clearance passage or actually providing a grooved passage in barrel portion 50 similar to the grooves 31a in Fig. 1.

In the operation of a pump incorporating the bushing arrangement of Figs. 4 and 5, discharge pressure is con municated to the offset primary motive surface area 46 of the cover 41 urging the cover to the right, as viewed in Fig. 4, into sealing relation with the associated pumping gears. Since the larger portion of the area 46 is disposed adjacent the outlet of the pump, the pressure loading force will be more effective against the gear side faces nearer the outlet of the pump. At the same time, however, inlet pressure is communicated to the oppositely offset, secondary motive surface area provided at the base of recess 44 and since the larger portion of this area is disposed adjacent the inlet of the pump, the cover will tend to move against the gear side face portions disposed nearer the inlet of the pump in response to inlet pressure. By increasing or reducing the size of recess 45, the extent of the area of recess 44 exposed to inlet pressure, and consequently the extent of compensation for high inlet pressure may be controlled within close limits wholly independently of the adjustment or control of the area 46 exposed to discharge pressure. Further, by varying the size of aperture 43 the over-all response of the cover to gear side face pressure may be controlled.

In order to facilitate description, the bushing assemblies have been described as generally cylindrical in configuration, this being the conventional pump bushing configuration. It will be understood, however, that the pres ent invention is equally adaptable to either curvilinear or angular constructions and similarly the recesses and bosses may have a curvilinear or angular configuration. Generally, however, the cylindrical configuration shown is more readily adaptable to mass production techniques.

From the foregoing, it will be evident that the bushing assembly of this invention may be constructed so as to require no modification of the conventional pressure loaded type pump housing bushing receiving cavity and, accordingly, the bushing is interchangeable with the usual type of bushing. It will be apparent, also, that by virtue of this interchangeability feature, it is feasible to provide several sets of bushing assemblies having different dispositions or proportionings of the motive surfaces so that by using one or the other of said sets, the pump may be adapted to accommodate for a wide range of force gradients across the forward surfaces of the bushings.

While this invention has been described particularly in conjunction with a pressure loadable intermeshing gear type pump, it will be evident that it is equally applicable to vane type pumps employing a pressure loadable end plate.

Where herein the various parts of this invention have been referred to as being located in a right or a left position, or an upper or a lower position, it will be understood that this is done solely for the purpose of facilitating description and that such references relate only to the relative positions of the parts as shown in the accompanying drawings.

What is claimed is:

1. An intermeshing gear type pump having pumping gears and having bearing means embracing axially extending gear journals in journal relation and sealably engaging the corresponding gear side faces, said gear journals extending axially through said bearing means and said bearing means being particularly characterized by being formed in a plurality of axially disposed relatively movable parts, those partswhich sealably engage the gear side faces being axially movable independently of said gear side faces, a first pressure responsive motive surface provided on said bearing means and eccentrically and perpendicularly disposed with respect to the axis of said journais, and a second pressure responsive motive surface provided on said bearing means oppositely eccentrically disposed with respect to the axis of said gear journals, said two surfaces being axially displaced one from the other, sealing means isolating said first and second motive surfaces, and passage defining means for continuously communicating inlet pressure to said first surface and discharge pressure to said second surface.

2. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, an axially adjustable end plate assembly received in said pump chamber and adapted to engage the side surface of said rotatable member in pumping seal relation comprising a cover member and a barrel member assembled in telescopic relation, said cover member being axially movable independently of said rotatable member, a first surface area on said cover member facing away from said rotatable member, a second surface area on said cover member engageable with the adjacent side face of said rotatable member to provide a pumping seal therewith, said second surface area being subject to a pressure gradient extending from a minimum value adjacent the inlet of the pump chamber to a maximum value adjacent the outlet of the pump chamber, a third surface area on said cover member facing away from said rotatable member, passage defining means effective continuously to direct pressure liquid generated by said rotatable member to the first surface area of said end plate assembly for urging the cover member of the end plate in the direction of the adjacent gear side face, passage defining means effective continuously to direct pressure liquid admitted to said pump at said inlet to the third surface area of said end plate assembly for urging the cover member of the end plate in the direction of the adjacent gear side face, said first and third surface areas being eccentrically disposed with respect to said second surface area and lying in spaced parallel planes.

3. A pressure loadable bushing assemblycomprising a cover member and a barrel member, said assembly having an aperture extending axially therethrough, said cover member having a recess formed on one side thereof, a complementary protruding portion of said barrel member adapted to be received in said recess, said recess and said protruding portion being offset with respect to the axis of said axially extending aperture, sealing means disposed between said recess and said protruding portion, and separate passage defining means for continuously communicating inlet pressure to the portion of said cover member lying on one side of said sealing means and discharge pressure to the portion of said cover member lying on the other sideof said sealing means, said lastmentioned portions being axially spaced.

4. A fluid pump comprising a housing for enclosing a rotatable pumping member, said housing having a pump chamber formed therein symmetrically disposed with respect to said rotatable member, said housing having an inlet leading to and an outlet leading from said pump.

chamber, a pressure loadable bushing assembly receivable in said pump chamber and adapted to engage at its forward surface the adjacent side surface of said rotatable member in sealing relation, said assembly comprising a cover member and a barrel member having an axially extending aperture formed therethrough, said cover memher being axially movable independently of said rotatable member, said cover member having a recess formed on the rear side thereof, a boss on said barrel member disposed in said recess, a first pressure responsive motive surface disposed radially outwardly of said recess in said cover member and eccentrically disposed with respect to said axially extending aperture, a second pressure responsive motive surface defined substantially by the base of said recess and displaced along said axis aperture from said first surface, means for continuously communicating pump discharge pressure to said first motive surface, and means for continuously communicating pump inlet pressure to said second motive surface.

5. A fluid pump comprising a housing for enclosing a rotatable *pumpingtmember, said. housingrhavingt a pump. chamber formedrtherein symmetrically: [dlSPOS6d'l\VlthiT-q spect to said rotatable merit-ber, said housinguhavingtan inlet leading' to andan ontnetileading. from tsaidtpump chamber, a pressure loadable bushing: assembly receivable insaid pump chamber: andadapted to engage at its for ward surfacethe adjacent sidez surface ofsaidvrotatable member .in sealing relation; -.the :forward surface of said assembly being axially movable independently. of, said rotatable member, said assembly comprising a cover mem ber and a barrel-member, saidtover-anember having a recess formedonthe .rearside thereof; a boss on said barrel member disposedzintsaid recess, anannular pres sure respons ve motive surface .extendingradially out wardlyof said-recesswand saidbossandihaving the area.

thereof adjacent the inlet:sidef;of said pump reducedas compared-with the-area thereof: adjacent the outlet side of said pump," a secondlannular pressure responsive motive surface extending radially inwardly of saidfirstpresconduit defining means pump discharge. pressure conduit definingmeans pump inlet. pressure to member in sealing-relation, saidtforward surfaceof said.

bushing assembly jbeingaaxially movable independently of said rotatable membenisaid assembly comprisingua cover member and a barrelzmember,

on said barrel member. disposed in said-recess, an annular pressure responsive motive surface extending radially outwardlyr of'said recess and said boss and having the area thereof. adjacent theinlet sideHofsaid pump re duced as compared with the area thereof adjacent the outlet-side of said pump, a second annular pressure responsive motive surface extending-radially inwardly of said first pressure responsive motive! surface, conduit defining means-for continuously, communicating pump discharge pressure to said first motive surface, andconduit definingmeans for continuously. communicating pump inlet pressure to said second motive surface, said recess being offset with respect to the axis of said bushing assembly whereby said first surface is offset toward the discharge side of said pump and said second surface is offset toward the inlet side of said pump.

7. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, an axially adjustable end plate assembly received in said pump chamber and adapted to engage the side surface of said rotatable member in pumpin seal relation comprising a cover member and a barrel member assembled in telescopic relation, a first surface area on said cover member facing away from said rotatable member and normally spaced'from the adjacent end wall of said barrel member, a second surface area on said cover member axially movable independently of and engageable with the adjacent side face of said rotatable member to provide a pumping seal therewith, said second surface area being subject to a pressure gradient extending from a minimum value adjacent the inlet of the pump chamber to a maximum value adjacent the outlet of the pump chamber, a third surface area on said cover member facing away from said rotatable member and normally spaced from the adjacent end wall of barrel member, passage defining means effective to Inuously direct pressure liquid generated by said romember to the first surface area of said end plate s may for urging the cover member of the end plate in the direction of the adjacent side face of said rotatable member, a second p sage defining means effective to continuously direct .sure liquid admitted to said pump at said inlet to the third surface area of said end plate assembly for urging the cover member of the end plate in the direction of the adjacent side face of said rotatable said. cover member having a recess :forrned ion-thereansrdethereofga boss member, said first-and thirdsurfaceareasbeing ,eccentrica'lly disposedwith respect ;to saidsecond surface area whereby the-tsealing force produced in response to appli- I cation of pressure thereto is nad e to have a. force gradient; corresponding the second surface area, saidsecond passage ,defining means comprising an aperture formed in said covermember and extending fromt said third surface areauto the pump inlet.

8. A fluid pump comprising a housing for enclosing. a.

rotatable pumping member, said housing having a pump chamber formed therein symmetrically disposed with re-n spect to said rotatablermembenmaid housing having. an inlet leading to and an outlet leading from -said.pump{ chamber, a pressure loadable bushing assembly receivable in said pump chamber and adapted to engage at its,.for-.

ward surface the adjacentaside. surface .of sai clrotatable. member in sealing relation, said forward surface of.sa1d

bushing assembly being axially movable independently of, said adjacent side surface of said rotatable member, said assembly comprising a cover member and a barrel meme ber, said cover member having a recessformed onlthe, rear side thereof,a boss onsaid barrelmember disposed. in said recess, an annular pressure responsive motive sur face extending radially outwardly of. saidrecess and said boss and havingthe area. thereof adjacent. theinlet side of said pump reduced ascompared with the areathereo f.

adjacent the outlet side. of. said pump, a second annular f pressureresponsive motive surface dispose-d radially in-I wardly of said first pressure responsive motive surface, X conduit defining means for continuously communicating. pump discharge pressure to said firstmotivesurface, ,and'

means for continuously communicatingpump inletpresk sure to said second motive, surface comprising-an aperture formed in said cover.member and extending from. to, the inlet of said pump, said recess being offset with respect to theuaxis ,of said bushing assaid second surface sembly whereby said first. surfaqe is offsettoi 2rdthe discharge side of said pumptand said second surface is offset toward theinlet sideofsaidpump. l

9. A fluid pump comprisinga housinghavinga pump chamber. formed therein, said-housing hayingan inlet" leadingto and anl outlet leading from said pump chamber, means including a rotatable member received .in saiclv. pump chamber effective to forcefluid from said inlet out of said. housing through said outlet, an axially adjustable:

end plate assembly received in said pump chamber and adapted to engagethe side surface of said rotatable mem ber i pump a r l tion. ompri in a .wyer mem er. and a barrel member assembled in telescopic relation, a first surface area on said cover member facing away from said rotatable member and normally spaced from the adjacent end wall of said barrel member, a second surface area on said cover member axially movable independently of and engageable with the adjacent side face of said rotatable member to provide a pumping seal therewith, said second surface area being subject to a pressure gradient extending from a minimum value adjacent the inlet of the pump chamber to a maximum value adjacent the outlet of the pump chamber, a third surface area on said cover member facing away from said rotatable member and normally spaced from the adjacent end Wall of said barrel member, passage defining means effective to continuously direct pressure liquid generated by said rotatable member to the first surface area of said end plate assembly for urging the cover member of the end plate in the direction of the adjacent gear side face, a second passage defining means effective to continuously direct pressure liquid admitted to said pump at said inlet to the third surface area of said end plate assembly for urging the cover member of the end plate in the direction of the adjacent gear side face, said first and third surface areas being eccentrically disposed with respect to said second surface area whereby the sealing force produced in response to application of pressure thereto is made to have a force gradient corresponding substantially to the pressure gradient across the second surface area 10. In a pressure loaded pump having pumping gears, an axially apertured bushing having a first motive surface eccentrically and substantially perpendicularly disposed with respect to the axis of said bushing aperture and arranged to respond to pump inlet pressure to tend to move said bushing into sealing relation with said pumping gears, and a second motive surface eccentrically and substantially perpendicularly disposed with respect to substantially; to thegpressure gradient across 1 the axis of said bushing aperture and arranged to respond to pump discharge pressure to move the bushing into sealing relation with said pumping gears, said second motive surface being axially displaced from said first motive surface, said bushing including means permitting the areas of said first and second motive surfaces to be varied independently of each other.

11. In a pressure loaded pump having pumping gears, an axially apertured bushing having a first motive surface eccentrically and substantially perpendicularly disposed with respect to the axis of said aperture and arranged to respond to pump inlet pressure to tend to move said bushing into sealing relation with said pumping gears, and a second motive surface eccentrically and substantially perpendicularly disposed with respect to the axis of said aperture and arranged to respond to pump discharge pressure to move said bushing in sealing relation with said pumping gears, said two motive surfaces being axially spaced from each other, said first motive surface having the larger portion of its area located adjacent the inlet side of said pump, said second motive surface having the larger portion of its area located adjacent the discharge side of said pump, said bushing including means permitting the areas of said first and second motive surfaces to be varied independently of each other.

12. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, an axially apertured end plate received in said pump chamber axially movable independently of and adapted to engage a side surface of said rotatable member in pumping seal relation, a first continuous annular surface area on said end plate facing away from said rotatable member and normally spaced from the adjacent end wall of said housing, a second surface area on said end plate engageable with the adjacent side surface of said rotatable member to provide said pumping seal, said second surface area being subject to a pressure gradient extending from a minimum value adjacent the inlet of the pump chamber to a maximum value adjacent the outlet of the pump chamber, a third continuous annular surface area on said end plate facing away from said rotatable member and normally spaced from the adjacent end wall of said housing,

' said first and third surface areas being eccentrically disposed with respect to said second surface area and oppositely eccentrlcally disposed with respect to each other,

said end plate further including means permitting the area of said first and third surfaces to be varied independently of each other.

13. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, an axially apertured end plate received in said pump chamber axially movable independently of and adapted to engage a side surface of said rotatable member in pumping seal relation, a first continuous annular surface area on said end plate facing away from said rotatable member and normally spaced from the adjacent end wall of said housing, a second surface area on said end plate engageable with the adja cent side face of said rotatable member to provide said pumping seal, said second surface area being subject to a pressure gradient extending from a minimum value adjacent the inlet of the pump chamber to a maximum value adjacent the outlet of the pump chamber, a third continuous annular surface area on said end plate fac ing away from said rotatable member and normally spaced from the adjacent end wall of said housing, said first and third surface areas being eccentrically disposed with respect to said second surface area and oppositely eccentrically disposed with respect to each other, passagedefining means effective to continuously direct pressure liquid generated by said rotatable member to the first surface area of said end plate assembly for urging the end plate in the direction of the adjacent gear side face, and passage-defining means effective to continuously direct pressure liquid admitted to said pump at said inlet to the third surface area of said end plate for urging the end plate in the direction of the gear side face in sealing relation, said end plate further including means permitting the area of said first and third surfaces to be varied independently of each other.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,780,109 Berglund Oct. 28, 1930 1,972,632 Patton Sept. 4, 1934 2,044,873 Beust June 23, 1936 2,312,655 Lauck Mar. 2, 1943 2,444,165 Lauck June 29, 1948

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