US2617360A - Fluid displacement device - Google Patents

Description

Nov. 1l, 1952 v. D. BARKr-:R

FLUID DISPLACEMENT DEVICE 5 Sheets-Sheet l Filed May lO, 1945 M a mf s@ Nm w N M w Nm Nm mm m r m. mm NQQDN .iv NME: @nu R ::MH wm o .f r l mw IUI mmm l @NIW Lnv Y Il f l bv O 'l &\l ,l 1 Q, H: @n q mm. W :Hl uw NN m5 r .l S o II Il D m i a wi m TFM n RP `Y O E TB N m. fm WD WT. q V

V. D. BARKER FLUID DISPLACEMENT DEVICE Nov. 11, 1952 5 Sheets-Sheet 2 Filed May l0, 1945 @moww l INVENTOR Virgil D o'zrker BY '/MTNEYS V. D. BARKER FLUID DISPLACEMENT DEVICE Nov. 1l, 1952 Filed May 1o, 1945 5 Sheets-Sheet 5 INVENT R 'Virgil D Barker Nov. 11, 1952 v. D. BARKER 2,617,360

FLUID DISPLACEMENT DEVICE Filed May 1o, 1945 5 Sheets-Sheet 4 INVENTOR Nov. ll, 1952 v. D. BARKER 2,617,360

FLUID DISPLACEMENT DEVICE lll`\ fr, J

2 d f '435 h N a 1- -v C j( a I? q g, I J f vq h 7 1 a 5 l 7 9 s 70, 2 l/ a` 4, 6 7 8f 70 10 ,A 4 /l/ ,Y ,X X 2 f 9 2 4, 1 3 6 5 I,9// 7 9 f' 1 s f 5 f 7 l, 5 f f L y f L f W13 wwf/'Wsw Patented ov. 1975-72 unirsi)V f sTArEfs PATENT, OFFICE i FLUID DISPLACEMENT DEVICE.

VrgiltD. Barker, WesteltLN. J. AllplicationMay 10, 194:5,7-S7er'ia1No.'593,'027

21 Claims. l

This invention relates to iluid pumps, Iand; it will be disclosed and discussed in that connection. Various aspectsof theinventionare, how.- ever, applicable -to iiuid displacement, devices gen.- erally, .including fluid motorsV andr fluidvpower transmissions.

In the preferred form hereindisclosed, theinvention is concernedwith avariable displacement high pressure pump, and more` particu1arly,'with a pump having a rotatable cylinder. blockl pro.- vided-with cylinder. boresr Whose axes are parallel to .the aX-is of rotation. of .the cylinder block.. In each cylinder bore opposedpistons are .operable to Yeffect pumping. action. Normallystationary cam members cause the pistons to havepumping action as thecylinder blockis rotatedwithin a pump housing, these cam membersbeingrelativee ly adjustableito shift the phase ofthe piston cyclesand to thereby control the'pump output.

The related prior art pumps of which I am aware, have yinvolved means for causing reciproeating action of the pistons such that thepiston motionv has been AVirtually sinusoidal,"or vharmonic. Thus, the piston cycles are such that the rate of displacement of any piston is never zero for anysubstantial proportion of a, piston cycle, and it. is therefore necessary that communication WithV each cylinder bore be shifted almost in-i stantly from connection to an inlet'. to connection with an outlet, or "vice versa.. The valving action has .been accomplishedy generally. by' some form'lofrotary motion between two iiat 'or cy-Y lindrical surfaces `having coacting` .ports for al;- ternate connection ofthe cylinder bores .with inlets and; outlets. This means that thequick shifts from inlet to outlet can be'obtained'only if the main inlet and outlet'ports are sealed from veachA other by very short moving seals';"an d such arrangements tend to leak iuid'underhigh pressuresgeven though the coacting parts of the valve mechanism' are constructed tovery close tolerances. If the seallengthsare increasedgthe cylinder bores are then not completely lled on their suction strokes, -or' the pistons unduly com'- press-thefluid before the outlet port is opened, resulting-in excessive vibration, noise," lossof powerfhighl stresses --anda h-igh degree-ofwear on parts subjectedto 'bearing-A p-ressures'.

A general object cf the presentiinvention is to provide va pum-p -offsuch constructionthat these defects or disadvantagescan bef-suitably eliminatedl or minimized and in thepump herein disclosed thepiston'motions are such that the eiTective displacement from any cylinder'borejmaybe conveniently reduced to zero for a suicientpro-V portion of the cycle to facilitate the usejo'f longer sealsjand adequatevalving' cycles.

'Ifheiinveption Hincludes within its 'purview a purnpjemployng a pair 'of coordinated'cams to produce a vsmoothperiodic. pistonmotion Whichis not a true harmonic. lilaclficanji vmay be so con,- structed `and arranged with reference tothe num; bers of pistonsV .and cylinder bores as. toiresult in 'uniform puvlsationlessA flow 'and' continuous balance of all` hydraulic inertia andv bearing forces, at various ovv, rates.V

The inventicn aISO provides a. pump in which the'valving is accomplished by the 'enacting m0- uons. of .opposed pistqnsiin. a, commoncylnder bore, 'the cylinder boreincorporating inletjand outletV` ports in its Wall. These ports 'are opened and closed 'inthe proper sequence by the pistons themselves-and, consequently', rany need for sepa;- ratejvalveelements is eliminated. In."the valv- 'ing of the' pump herein disclosed the necessary close ts betweenpistons andcylinder' bores inherently. Iand automatically function tojp-rovide close t valving at no eXtra cost in precise' manufacturing operations.

Control of the rate and direction` of output fluidjow is, accomplished through veffective uti lization of the'arrangementof opposedpistons in each. of a plurality of cylinder bores. .The cyl,- inderbores are .arranged with .their axes parallel to 'the axis of pump' rotation, and the rcciprof 'catory'relative motion.V between4 the pistonsand the'cylinpder block is attained bythe use of .apair of cams 'which are normally stationary.A All' for" thepistons Whichface in one direction areV controlledby oneof the cams,7 and allof thepistons which face inthe0the1'-direction are controlled by, theotherfcam. The; cams are similar,. but of vopposed contour, and preferably .cause each piston to executethes same .periodic motioninvolving dwell, acceleration, stroke andA deceleration. All' elements 'of piston motion are repetitive in pattern and magnitude,

Amongjthe objects of the invention accom.- plished by the herein disclosed pump are: increased mechanical andr volumetric efficiency; marked. reduction of Vuid lossdue to leakage; balance of forcesimposed by hydraulic orinertia loads Withinv the pump, thus eliminating lthe necessity' for large and costly bearings; .reduction of parts; component parts of such construction that they may be machined to closevtolerances by available manufacturing methods at comparatively low cost; a high degree of sensi.- tivity of the pump in response to control impulses from simple control mechanisms; uniform'rates 3 of flow at all magnitudes of displacement; and marked reduction of vibration and noise.

My invention is clearly dened in the appended claims. In the claims, as well as in the description, parts are at times identified by specific names for clarity and convenience, but such nomenclature is to be understood as having the broadest meaning consistent with the context and with the concept of my invention as distinguished from the pertinent prior art. The best form in which I have contemplated applying my invention is illustrated in the accompanying drawings forming part of this specification, in which:

Fig. 1 is a longitudinal vertical section of the pump taken in general on the line I I of Fig. 2;

Figs. 2, 3, 4, 5 and 6 are vertical sectional views taken in general on lines 2 2, 3 3, 4 4, 5 5, and 6 6, respectively, of Fig. 1;

Figs. 1, 8, 9 and 10 are views illustrating one of the cams used to actuate the pistons. These views show the cam before assembly, and the position of the cam in these views bears no relation to the assembled position shown in Figs. l, 2 and 5. Fig. '7 is an elevation. Fig. 8 is a section on line 8 8 of Fig. 7. Fig. 9 is an edge view looking from the bottom of Fig. '1. Fig. 10 is a perspective View.

Fig. 11 is a partly diagrammatic view, including an enlarged longitudinal section of one of the pistons;

Fig. 12 is a diagrammatic development illustrating the reciprocation of the pistons, the Valving, and Variable displacement; and

Fig. 13 is a diagram indicating the uniform rate of flow for any effective displacement.

The pump shown in the drawings has ten pairs of opposed pistons, one pair operating in each of ten cylinder bores. Fig. 1 shows two pairs of the pistons in an instantaneous position. For convenience and clarity, the actual position of the pistons is disregarded in Figs. 4, 5 and 6; and in these figures each pair of opposed pistons is assumed to be in the same position as the two pairs shown in Fig. 1.

The housing of the pump shown consists of three main parts. The central housing section. designated as a whole by I5 (Fig. l), is formed with a main bore I6 within which the cylinder block 49 rotates in spaced relation. Housing I5 also has cam counterbores I1 and I8, a bore I9 for the control piston, and attachment flanges 26 and 2I. The rear housing or housing section, designated as a Whole by 22, is provided with an attachment ilange 24 secured in fluid-tight relationship to the flange 20. Housing section 22 also has a cam counterbore 25, a pintle bore 26, fluid passages 21 and 28 (see also Fig. 3) and a control piston bore 29 aligned with the bore I9 of the central housing section I5. The counterbore 25 combines with the counterbore I1 to form a recess for the cam 39. The rear housing section 22 is also formed with legs or supports 3l, 3| for mounting the pump (see also Fig. 2). The front housing section, designated as a whole by 32, is formed with a ilange 34 that is secured in duid-tight relationship to the flange 2| of the central housing section I5. The front housing section 32 is further formed with a cam counterbore 35, which combines with the counterbore I8 in the central housing section to form a recess for the cam 46. Housing section 32 also has a bearing counterbore 36 and a control piston bore 31, as well as opposite legs or supports 38 (one shown).

The three housing sections I5, 22 and 32 are held in pressure-tight relationship by a suitable number of cap screws 39; and rear and front cover plates 4I and 42 are clamped to the rear and front housings 22 and 32 by a suitable number of cap screws 44. While sealing gaskets may be employed, I prefer that the mating faces of the housing ilanges, and the mating faces at the cover plates, be so machined and ground that leakage can be prevented without the use of gaskets.

Disposed centrally of the pump is a pintle provided with longitudinally-bored pairs of fluid passages 46, 46 and 41, 41 the arrangement of which is indicated in Figs. l, 2, 3, 4 and 6. The passages 46, 46 and 41, 41 may be blind or deadend passages, bored from one end of the pintle and having their ends closed by plugs 48. These plugs will ordinarily be slotted or otherwise recessed to receive a tool for screwing them home. but for clarity such recessing is not shown.

Pintle passages 46, 46 both communicate with horseshoe passage 21 in the housing section 22, and this horseshoe passage may be connected at 21a (Fig. 3) to a source of fluid supply. The rotatable cylinder block, designated as a whole by 49, is provided with an annular groove 50 which communicates with passages 46, 46, the communication being through transverse moonshaped cut- outs 52, 52 in the pintle (see also Fig. 4). The annular groove 50 also communicates with the left half of each of the cylinder bores 5I, the groove being so positioned that the port therefrom to each cylinder bore will be opened and closed by the left-hand piston as it reciprocates.

An outlet uid line 28a (Fig. 3) is connected to outlet passage 28 in housing section 22; and outlet passage 28 is in turn connected to the nearer of the fluid passages 41 in the pintle. Through crosswise bore 41a the outlet passage 28 is also connected to the farther fluid passage 41. The right-hand end of each of the longitudinal uid passages 41, 41 is in communication, through transverse moon-shaped cut-outs 53, 53 (Fig. 6) with an annular outlet groove 54 formed in the cylinder block 49. The groove 54 is so positioned that the port therefrom into each of the cylinder bores 5I will be opened and closed by the right-hand piston as it reciprocates.

The cylindrically surfaced pintle 45 is accurately machined and ground to form a tight iii; in the rear housing bore 26. Assembly may be by pressing pintle 45 into bore 26, or by shrinking housing 22 onto the pintle 45. The pintle has a very close running fit in the bearing 55 of the cylinder block 49.

Each of the cylinder bores 5I is provided with two grooves, 50' and 54', annular with respect to the cylinder bore axis, to prevent hydraulic side thrust of the pistons against the cylinder bore walls when the pistons pass through the annular passages 50 and 54. Each of the pistons, designated as a whole by 56 (see also Fig. 1l) may be considered as consisting of a working piston portion 51 and an integral crosshead portion 58 of larger diameter; and these portions have close running fits with differentially bored portions of the cylinder bores 5I.

Mounted in each crosshead 58 is a ball driver or cam follower 59, each ball driver being seated in a socket having a, spherical surface. The two pistons in each cylinder bore are biased apart at all times by a coil spring 60. Each such coil spring is substantially housed within a pair of 51' opposed'working pistonse. 56, `56ffwithsthe'fends. of each KVspring abutted against the shoulders 6| (Fig. 11) 'nea'r' the junction of each'workin'gfpiston jand its crosshead` 58.

Coacting with the pistons 56 are the'fcycle 'camsr 30 'and 40, 'positioned both axially and radially-byv counterbores 11,25and I8, 35,'respectively. The cams 30 and 40 are similarly arranged, andtheir contours are :so matched or `coordinated that' as the cylinder block'rotates the' cams effectthedesi'redcycle of reciprocation of each pair (and While lthen all pairs) of the opposed pistons. cam's arenormally stationary, they are' permitted angular' phase shiftin'gmovement which `for each cam is limited by a stop pin 62 that projects/into cam reces '64 (see also Figs.' 2 and 5). Eachcam, in azone diametricallyv opposite its recess =64`is provide'd'with 'a number'of helical gear' teethat.

65.` v'In camA 39the high zonesoil thecamming surfaceare diametrically aligned with the `recess 64 and the teeth at 65; in cam 49 the high zones' of the camming surface are displaced ninety degrees therefrom.

The cylinder block 49 'iS rotated by a shaft'66' journaled in bearings 61 and 68.l The'bearingy Slis mounted in a recess in the right-hand end ofpintle A45, as indicated in Fig. 1, and the bearing 68 'is a ball bearing mounted Ain therecess -36 of -thevhousing'section 32. Shaft 66 is driven by appropriate connectionsto a motor. 'Thefdriving connection` between' the left-hand part of the' shaft/66 and the cylinder block 49 is aorded by a driver 69 keyed to thev cylinder block by -drive pins 10 (five shown in Fig. v5) The driver 69qhas.

a splined connection to the shaft 66 as indicated at 66', andthe driver is positioned axially by the bottom of the-counterbore 35 in the front housing lsection 32 (see the lower vright-handpart oi Fig. 1).

thefront housing 32. An annular spacer k'H performs a similar function with respect to the rear housing section 22. The front cover plate 42 is provided with a bore to support 'andposition parts`j1ll,"15'and 16 (Fig. 1), of which 'I4 "is described as acontrol piston and `'l5 vis a h'andwheel forturningjtherod 16 which positions control piston; The control piston 14 is longitudinally guided bythealigned bores 29, I9 and 3'l `within the;lrou'sin'gsectionsA and it is provided'near its opposite ends with helical gear tooth sectors 11, 'Il meshing with the cam gear toothsectors 65, -'ofithe'cams 39and 40 (Figs. 1 and 5). The control VpistonV is movable longitudinally by the rotation'of the control rod 'I6 the right-hand portion 16'- {'of which is provided with screw threads oactin'g" with internal screw threads V13 ina bore-of the-control piston. The handwheel 15 forturning thev rod 16 is provided with appropriate'graduations or indicia to show the position -ofthe control piston. The rod 'I6 is also provided with a iiange or collarr16a which, in cooperation'with'a face of the handwheel and the interposed' cover plate 4I will position-the rod against raxial movement.

In turn, the driver'69 restrainslthe. cylinder block 49 from moving axially toward' The gear sectors`65` and Il have: helicalteetli, preferablyl about forty-live degree helixia'n'gles` bearing against itsY respective stop. pin 62. `The.` control piston is notv keyed 'against rotationabout' itsown axis.A

In Fig. 11 of the'drawings there is shownan enlarged'central longitudinal section of one'of the twenty pistons' 56'ofthe Fig. 1 assembly. The body of the piston' is considered as tubular, having the Working portion`51 'formed' integrally with the head portionl 5S "of larger diameter. The portion 58 serves as a crosshead to support and guide the outer'end ofthe pistOn,"an'd`it:is provided with a spherically surfaced f socketfto receive' the-'ball driver 59, which may functionally be considered as a piston head'. Thes'ocketi's relieved as `at r to a diameter substantiallyfequal.' to theexternal diameter 'of thef piston'fportion! 5l.'y The bore 51 receivesone end of the ,pistoni return spring 60 (Fig. 1). The openingor'space* t within the main body of the pistonportion 5:1? communicates with the space at r throughith'e openingk q so that fluid under 'pressure' from'the cylinder bore fillsv the piston space at'r, q, andt;

and exerts its pressure 'directly against the ball 59. vSince the ball area`exposed to thisiluid pressure is substantially `equal to the cross-sec-V tional area of the workingportion 57 `of itheipis-VA ton, substantially allof the hydraulic lloadfagainst the piston is 'carried directly by the ball.- The axial load taken bythespheri'cal seat surfaceu consists of the force exertedby 'the spring -69' plus the force represented by theproduct ofthe unit fluid pressure `and the difference between the overall cross-sectional area-of Athe piston porf tion 51 andthe Iarea of the ball exposed directly to iluid pressure within the piston. Inadditionv to this residual axial'load' consideration .must begiven to the transverse force components due to the'rolling of the ballon the inclinedcamsurface.

The total force between the cam and -th'e ball." 59 may be represented by the vector x at a'nangler of inclination w. The axial component 6fm is y1,

most of which is counterbalanced'byfthe 'uidpressure effective on ball 59 through opening lp',

and only a little of which has'to be carried 'byl seat surface u. The transverse component 'f' is e directed at right angles to the piston axis and substantially toward the sphericallysurfacedA seat u. From this analysis, and the-'- disclosure in the drawings- (Figs. 1 and 11), it willappear that the spherical seat is not undulyloaded'feitherA` axially or transversely. The axial `load on the spherical seat is relatively small, andthe" seatv has a wide and'ample bearing surface to v'withistand the transverse force component. lThe ballV will therefore roll freely in thesocket and, at the same time, it will seall the socket against fluid leakage. This is particularly apparent whenit is considered that the bearing surface 'between' the face of the socket 'u and the ball 59 isalwa'ys well supplied with fluid under high4V pressure tol serve as a-lubricant.

In operation, the loaden the piston' 56l` is rap'g-xv idly changed from high to low pressure, and the direction and magnitude of the transverse force components are also changing. These changes occur rapidly during a piston movement of sixty cycles per second (for example) and insure ample renewal of the lubricant between the ball and its seat. The ball and seat construction is also such that there is automatic compensation for wear.

Each of the springs 60 has its opposite ends seated Within the bore of piston portions 51, 51 of opposed pistons 56, 56 as indicated in Fig. 1; and each spring, therefore, causes the two pistons to be constrained to follow the contours of the cams 30 and 40, respectively. With the construction shown, the forces required to accelerate the pistons to make them follow the cam contours are well within safe values which can be attained by springs fitting the spaces provided by the pistons. For example, a driving speed of 1725 R. P. M. requires a maximum spring pressure of the order of thirty pounds.

By further reference to Fig. 1 it will be noted that annular grooves 80 in the cylinder bores are in communication with the central housing bore I6 through openings 8|, the cylinder block being drilled to provide the latter openings or passages. They permit a free flow of fluid to and through the enlarged outer ends of the cylinder bores I to accommodate the pumping effect of the crossheads 58. The cylinder block is provided with annular channels as at 82 (one shown) for rotating clearance for the driving lobes of the cams 30 and 40.

The space adjacent to the cams 3Q, 40 and the space between the housing and the cylinder block 49 may be kept lled with the oil or other fluid being pumped. In this case valve 83 is kept closed. The aforesaid space may, however, be kept dry by keeping valve 83 open and constantly draining any excess oil through pipe 93 to the sump or other fluid reservoir.

The above-described construction including the ball driver and the coacting piston construction presents a thrust transmitting means which reduces the real bearing force to a fraction of the value which might be supposed. This results in low friction loss and greatly reduced wear. In turn these results contribute to the high efficiency of the pump when operating at greatly increased pressures. They also contribute to long operating life. jor portion of the hydraulic force on the pistonand-ball is imposed directly on t -e ball, which rolls on the cam; and, in a sense, the part which has been called a piston is not a piston but serves as a guide for the ball and as a packing between the ball and the cylinder bore. This advantageous thrust transmitting construction also provides a high degree of freedom in the designing of cam contours, and in ranges of hydraulic pressure not heretofore possible.

In the illustrative pump each piston moves in a cycle of constant magnitude; and since the stroke of the piston is never varied, any reduction in the effective displacement must appear elsewhere in the cycle. Angular phase adjustment of one cam with respect to the other, in effect, causes a so-called subtraction from what may be termed the effective pumping stroke of the cycle. This phase adjustment also causes the conversion of the subtracted portion of the stroke to a motor stroke which returns to the inlet or supply line an amount of uid equal to the amount subtracted from the outlet. This so-called subtraction is an advantageous way of reducing the total rate of flow since the return of In this construction the mafluid to the inlet is a motor stroke and there is no loss of energy. The net power taken by the pump is proportional to the net output of fluid under pressure. If the phase adjustment is sufficient to cause a subtraction in effective displacement equal to one-half the maximum effective displacement (geometrical displacement) the net output is then zero. Further phase adjustment in the same direction causes the flow to reverse, and as the phase adjustment is continued in the same direction the reverse ilow is increased to maximum.

A corollary of this principle of variable flow is that the length of seal between the inlet and outlet ports is maximum at zero flow, and near maximum at small rates of flow in either direction. This is particularly advantageous where it is desired to pump accurately at small rates at high pressures to effect such results as slow heavy cuts on machine tool feed applications.

A better understanding of the operation of the illustrative pump may be had from reference to Figs. 12 and 13. Fig. l2 is a developed diagrammatic representation of various successive positions of a pair of pistons in one cylinder bore. Since all pistons execute two identical pumping cycles per revolution only one cycle of degrees is represented. The pistons are indicated at increments of eighteen degrees of cylinder block rotation, the center lines of the pistons in the successive positions being denoted by the reference characters a, b, and c, etc. The cylinder bores are represented by transverse zones A, B and C where A is the central cylinder bore section between the annular ports 50 and 54 and B and C are the two outer guide sections of the cylinder bore. D and E represent the two ports 50 and 54'. The stationary cams are represented by the curves C1 and C2, in which curves the dotted lines indicate the path of the center of the ball driver 59 and the solid lines the` developed cam profile required to produce the dotted line motion.

Starting at the left, the dotted line C1 from a to c represents a thirty-six degree dwell of the piston P1. From c to d, this dotted line indicates a constant inward acceleration of piston Pi during eighteen degrees of rotation of the cylinder block 49. The dotted line C1 from d to f represents constant inward velocity of the piston P1 during thirty-six degrees of rotation of the cylinder block. From ,f to g, the piston P1 has a constant inward deceleration during eighteen degrecs of the cycle; and in the next part of the cycle from g to h the piston has an eighteen degree period of constant outward acceleration. From h, to 7', there is a thirty-six degree period of constant outward velocity. From i to a, there is an eighteen degree period of constant outward deceleration.

The dotted line or curve C2 represents the movement of opposed piston P2 during the cycle just traced for piston P1. Line g indicates the point on cam curve C1 where the piston P1 is advanced to its farthest inward position; and m indicates the point on cam curve C2 where the piston P2 is advanced to its farthest inward position. Lines b-b' and n n are center lines at which the pistons P1 and P2, respectively, have their farthest outward positions. The distance q between n-n and g-g is the phase displacement between the two cams from the position where the net flow is zero. When n n coincides Assu-rnethatthe motion 'of thecylinder block is to thelright'(Fig.`12) as indicatedY by the arrows q is negative (as is indicated in Fig. 12),then`.

D is the inlet'port and E is the outlet port. If q is positive, E is the inlet' and. Dis the outlet.

Considering the successive positions of the pistons'as the cylinder block rotates froma to y', it will beseen that the piston P1 dwells from a to c, and starts moving under constant acceleration at c. At d this piston has moved enough to close the port D. At m the piston Pz starts its outward movement, creating a suction v'stroke up to the position Yd. Atthis time the port D is closed. From 'd tok-7c both pistons'move atthefsame constant 'velocity and at 7c the outlet'port-E starts to open. The piston Pz decelerates from 1c to a and'thenv dwells for thirty-six degrees. The

other piston P1 follows through to gfproducing a pressure or output stroke.

From g to h the piston P1 is accelerated outwardly, and at l-Z the piston P2 has vfollowed to point of closing the outlet port E.- From If-Z to lg-/j the-two-pistons move 'together with no relative displacement. Thus it will be seen that during the Z-Z to :i-i portion of the cycle ythe two pistons have trapped and are returning a certain quantity'of'liquid from the outlet port to Ythe inlet port. A Sportion .ofVv this trapped liquid corresponds to the minimum distance betweenVV the two pistons; apparent at g--g' and the remainder corresponds tothe. distance that-thepiston `P1 withdraws inthe period h--h tol-l. This disl tance h--h to -Z-Z is always equal to-the difference between eighteen degrees and the value of q. If '(1 is made smaller, Athen h to Z becomes larger and, similarly. the eiectiv'e displacement of uid from D to E becomes smaller and the return displacement from E to D becomes larger.

This can be visualized by assuming a gradual movement of the cam curve Cz to the right relative to the 'cam'curve C1.

In adjusting for various ratesor 'forward ilow,`

it is 'preferable to hold one cam"'stationary .in

thepump .casing and shift the otherone to 'oh-4 tain thephase displacement between cams. In adjusting for-various ratesV of reverse'lomit is preferable'to hold the-second'cam stationaryin the pump casing and shiftthe rstone to'obl The reason for this may bev understood from reference to Fig. 12`.l With q negative as shown in Fig'.` 12, and E the tain the-phase displacement.

During this interval disclosed; adjustments toV vary` the value `Vof so long Vasd is negative, will shift only cam'Czf while cam C1 will be stayed by its'stop pin 62.v`

When q becomes positive and'D is the outlet,- the torque 'reaction transfers to stop pin' 62 of'caxny C2. I In adjusting to various values of q, with'q positivegcam C1 shifts, while cam C2 is stayed'by its-*stop pin 62.

Thismethod lends itself to execution byex-ltremelysimple control mechanism.: It is en' f Vtirrelyconsistent with the use of -the controlz'piston ,disclosedQand if desired the control pistonfflma'yefl be "adjusted "byfremote* cont-rol. or: serve vcontrol apparatus. pump shaft GBbe reversedthe stoppins 62-funcjA tion inthe same manner but againstthe Vopposite ends of camrecessesrl.' y

Understandingof the-functioning of theillustrated pump may-bepromoted by assuming that the positionsa, c, fe, y, and-z also represent ve consecutive cylinder' bores and ve consecutive pairs of pistons.` This taken together `with Fig."

13 will providev'aclear understanding of the uniformity' of flow `at fall' adjustments.

Fig1r-13 is 'a velocity diagram showing theman-` ner'invv which thefcamsproduce a `uniformfnet rate-0f ilow 'for'4 any .'camadjustment. In -th'is diagram-'allof they velocity lines represent the, eiectsofsev'eral pistons-on the flow to orfrom the'outlet port; v I'hesolid 'lines and the-odd.

numeralsrepresent the--eiectof the P1 pistons A(Fig'. i12) and' the-dotted'lines andl even-numerals A represent the veffect of the P2 pistons. Plus values, above the zero-linesfindicate eiective flow toward the outlet portfand' minus values, below the zero lines; represent -eilectivey flow *awayl fromf the outlet" y Referring, for example,vl toV pistons 5 and 6 (Fig.v 13),f`piston5 maybe' considered as starting to pump iluid into thefoutlet'port E (see Fig. 12)

at lc when the piston-B Vopens the `outlet port. Pistoni moves'=at`fconstantvelocity from lc to f.

At'fit .changestoconstant deceleration', and at g to'constant'reverse acceleration. At h pistonY 5 changestoconstant' reverse velocity.' The foregoingvelocitypatternl of. piston 5 is represented by'th'e -f'solidv line r5'-5-15-`5 extending from` lc to 4Z. l Th'efiloweiectA of pistony 5 must be considered? to `stop'` at.v l whenl 'piston 6 closesqthe outletfiport Ei Similarly, -piston'G may be con--v sideredvto have a 'velocity' effect onthe outlet port" frepresented i by ythe dotted line 6--6-6. Velocity curves' may be similarly plotted for four other-pair'slof-pistons to 'makefa completeA div agram (for ve cylinder -bores and degrees). Thesum of allY of thefcurves will addup to thev heavy straight line SJ Curves for f two different phase'adjustmentsof the 'cams are shown; this means two diierent--values at q and two diierent valuesv of Aeiective pump'displacement. l'As the distance k-f is reduced the total i'low falls to .zero, and then increases in the reversedirection'.

The'iiow remains-uniform, however, atany adjustment: 1

The-ccmbinationoten cylinde1` Vbores and" doubleffre'quency cams results'in balanced forces. Even thef axial accelerating and Vdecelerating forcesron -thepistonr add up to zero for each cam," taken'separately.` Furthermore, all pistons perform two workingstrokes per revolutionand thismakesit possible to reduce the stroke by-one-half and; infturn,reduce' the lengths of pistons and cylinder Vboresfand the overall size of thepump.

For the 'purpose/of using the pump in a closed system'where: it is ydesirable thatthe system be always lled--with uid to avoid any entrapment of -air,fa small gear'type"makeup pump' may be mounted`r in the-front housing-section f 321 and drivenfdire'ctly by the'drive shaft 66. The outletH of this pump' may be connected by passages lin the housingsito both thefmaln inlet and outlet passages `2-I- and v28 through appropriate check valvesv located'iny therear housingV section 22".' In addi' provided forsthelmakeup pump and preferably locatedfonthe'kfront:housingsection 32.. Also, an @auxiliary reservoir or sumpmay-:be' providedior Si If the direction offrotation of' the a reserve supply of uid, and to permit the cooling of the working fluid.

The manufacturing methods required to build the illustrative apparatus are free from diiiicult types of operations, a preponderance of the precision machining consisting of cylindrical turning, boring, and grinding. The only special operations required are in connection with the production of the spherical seats for the ball drivers and in the production of the cams.

The illustrative pump is characterized by pulsationless tlow at all flow adjustments. It is also characterized by the balancing of all hydraulic and inertia forces. This results from the particular construction and arrangement of the cylinder bores, pistons and cams. The relative proportions of dwell, acceleration, velocity and deceleration in the structure of the cam result in the complete balancing of all inertia forces so that these forces on either cam always add to zero in thrust or radial load. These factors minimize vibration and contribute to low cost, effective operation and long life. For example, because of such balancing out of forces the cylinder block rotates with substantially no radial bearing load except its own weight, and with substantially no thrust in either direction. Hence no special bearings are required. The cams also need no special thrust bearings.

The cylinder block is the principal rotating element. It is driven by a simple stub shaft mounted in its own bearings to eliminate any possible unwanted load on the cylinder block bearing. The cylinder block rotates upon a pintle bearing which also contains inlet and outlet fluid passages registering with annular grooves in the cylinder block. With this port arrangement, the annular fluid passages are continuously connected to the same passages in the pintle and they are not alternately connected to inlet and outlet ports. This construction provides for the long seal (at least one-half inch) between the annular passages, and this seal is never broken.

The pintle 45 is required to carry only the weight of the cylinder block and pistons; and with no additional hydraulic forces it is possible to effect a very close running fit between the pintle and the cylinder block, without resort to special bearings.

A pump such as disclosed may be used at all rates of delivery from zero, or near zero, flow to its maximum capacity. As previously indicated, this device has the characteristic that the length of seal between the outlet and inlet ports is maximum at zero flow and near maximum at small rates of flow in either direction. For most uses I prefer that the confronting edges of the inlet and outlet ports be spaced by a distance equal to at least 50% of the stroke of each piston. With a given pump the degree of seal is proportional to the value of q shown in Fig. 12. For most uses I prefer that the maximum value of q shall not exceed an amount corresponding to a seal equal in length to approximately 8% of the total stroke of each piston. The maximum seal will correspond to a zero value of q and Will be equal in length to 25% of the total stroke of each piston. Expressed in terms of intervals during which valving may take place, these seal lengths make the displacement eiectively to be suspended a minimum of 2.5% of the total piston cycle for the minimum seal and the minimum interval. At or near zero flow the effective displacement is suspended for an interval of approximately 'l1/2% of thetotalpistoncycle.

This characteristic is of particular value in many applications where it is desired to pump at extremely high pressures when operating at low delivery rates, and where high pressures at high delivery rates are not required.

I claim:

1. A pump comprising; multiple cylinder bores and multiple pairs of relatively movable pistons, one pair reciprocable in each cylinder bore; a rotatable cylinder block in which the cylinder bores are formed, the cylinder bores having inlet and outlet ports in the sides thereof, the cylinder bores collectively being arranged annularly of the cylinder block axis and the cylinder bores individually being disposed with their axes parallel to the cylinder block axis; means to rotate the cylinder block; and means for reciprocating all of the pistons as the block is rotated, said last-men tioned means including a pair of normally-stationary cams and springs operative to bias the pistons toward the cams, a piston of each pair alternately covering and uncovering an inlet port and the other piston of each pair alternately covering and uncovering an outlet port.

2. A pump as in claim l in which there are means to adjust at least one of the cams to vary the effective displacement of the pump per revolution of the cylinder block.

3. A pump as in claim l in which there are means to reverse the direction of pumping flow while the cylinder block continues to rotate in the same direction.

4. A pump as in claim l in which there are means to vary the effective displacement of the pump per revolution of the cylinder block while maintaining constant the stroke of all the pistons.

5. A pump as in claim 1 in which the cams move the pistons of each pair to change the space between the pistons during the suction and discharge strokes and maintain said space constant during an intervening interval.

6. A fluid displacement device comprising: multiple cylinder bores and multiple pairs of relatively movable pistons, one pair reciprocable in each cylinder bore; a rotatable cylinder block in which the cylinder bores are formed, the cylinder bores having separate inlet and outlet ports in the sides thereof; and means to reciprocate the pistons as the cylinder block rotates, said means including a pair of normally-stationary cams and springs operative to bias the pistons toward the cams, the pistons covering and uncovering said ports and thereby effecting the cylinder valving.

7. A fluid displacement device as in claim 6 in which one piston of each pair covers and uncovers an inlet port and the other piston of each pair covers and uncovers an outlet port.

8. A uid displacement device as in claim 6 in which the cylinder block has an annular groove communicating with the inlet ports of all cylinder bores and has a Second annular groove communicating with the outlet ports of all cylinder bores, and the device is provided with a pair of iiuid passages, one in constant communication with each of said grooves.

9. A fluid displacement device as in claim 6 in which there is a pintle on which the cylinder block rotates, the block is provided with an annular groove communicating with the inlet ports of all cylinder bores and with a second annular groove communicating with the outlet ports of all cylinder bores, and the pintle is provided with fluid passages in constant communication with Said groaves. -1

Vand reciprocates the latter in'a cylinder bore,

and the cylinder bore is connected to an inlet passage during an intake stroke and is connected to an outlet passage duringa dischargeA stroke;

the improvement which comprises: the; piston means being two relativelymovable pistons, and the rdrive means moving the pistons in coordinated relationship for changing the space between the pistons during the suction and discharge strokes and maintaining said space constant during an intervening interval.

12. A uid displacement device as in claim 6 in which the confronting edges of the inlet and outlet ports are spaced by a distance equal to at least 50% of the stroke of each piston.

13. A uid displacement device comprising: a cylinder bore having a rst diameter for a portion of its length and an enlarged diameter for the remainder of its length, a piston in said bore, the piston having trunk portions of rst and enlarged diameters received by the rst and enlarged diameter portions of said bore, a spherically-surfaced seat formed in the piston portion of enlarged diameter, a ball tted to said seat, said ball having a diameter approximately equal to said rst diameter, and a cam engaging the ball and operative to move the piston in the cylinder bore, the piston having a passage through which the uid pressure from the first diameter portion of the cylinder bore is communicated directly to the ball to reduce the pressure between the seat and the ball.

14. A uid displacement device comprising: multiple cylinder bores and multiple pairs of relatively movable pistons, one pair reciprocable in each cylinder bore; a rotatable cylinder block in which the cylinder bores are formed, each cylinder bore having an inlet port in the side thereof and having a separate outlet port in the side thereof, the inlet and outlet ports for each bore being spaced lengthwise of the bore; and means to reciprocate the pistons of each pair as the cylinder block rotates and cause one piston of each pair to cover and uncover an inlet port and the other piston of each pair to cover and uncover an outlet port, said means including a pair of normally-stationary cams and springs operative to bias the pistons toward the cams.

15. A fluid displacement device as in claim 14 in which the device is provided with an inlet passage connected at all times to all of said inlet ports and with an outlet passage connected at al1 times With all of said outlet ports.

16. A fluid displacement device as in claim 14 in which one cam moves one piston of each pair and the other cam moves the other piston of each pair, and the curves of the cams are so coordinated that when both the inlet and outlet ports of a cylinder bore are covered the pistons move in the bore at constant spacing.

17. A fluid displacement device as in claim 14 in which the means to reciprocate the pistons so coordinates the piston movements that the sum total of the instantaneous rate of effective piston displacements in all of the bores remains constant.

T4 18. A uid. displac ment` device comprising: multiple cylinder bores and multiple pairs of relatively movable pistons, one pair reciprocable in each cylinder bore; a .cylindenblock in Which the cylinder bores are formed, the cylinder bores having inlet and outlet ports in the sides thereof,

vthe Vcylinder bores collectively being 'arranged annularly of the-cylinder block axis and--the cylinder Lbores -individually being disposed with their-axes parallel to the cylinder block axis :and meansinclud-ing a pair of Vcalms-for reciprocating 4all of lthe pistonsupon relative rotation between Vthe cylinder block and the cams, the cams movg ing the pistons of each pair to :change thegspace 'betweenithe pistons during theV suction and discharge strokes and maintaining said space constant during an intervening interval, a piston of each pair alternately covering and uncovering an inlet port, and the other piston of each pair alternately covering and uncovering an outlet port.

19. A iiuid displacement device comprising: multiple cylinder bores and multiple pairs of relatively movable pistons, one pair reciprocable in each cylinder bore; a cylinder block in which the cylinder bores are formed, each cylinder bore havingr an inlet port in the side thereof and having a separate outlet port in the side thereof, the inlet and outlet ports for each bore being spaced lengthwise of the bore; and means to reciprocate the pistons of each pair and cause one piston of each pair to cover and uncover an inlet port and the other piston of each pair to cover and uncover an outlet port, said means so coordinating the piston movements that the sum total of the instantaneous rate of effective piston displacements in all bores remains constant.

20. A iiuid displacement device comprising: multiple cylinder bores and multiple pairs of relatively movable pistons, one pair reciprocable in each cylinder bore; a rotatable cylinder block in which the cylinder bores are formed, the cylinder bores having separate inlet and outlet ports in the sides thereof; means to reciprocate the pistons as the cylinder block rotates, the pistons covering and uncovering said ports and thereby effecting the cylinder valving; and a pintle on which the cylinder block rotates, the block being provided With an annular groove communicating With the inlet ports of all cylinder bores and with a second annular groove communicating with the outlet ports of all cylinder bores, and the pintle being provided with uid passages in constant communication with said grooves.

21. A fluid displacement device comprising: multiple cylinder bores and multiple pairs of relatively movable pistons, one pair reciprocable in each cylinder bore; a rotatable cylinder block in which the cylinder bores are formed, the cylinder bores having separate inlet and outlet ports in the sides thereof; and cam means to reciprocate the pistons as the cylinder block rotates, the pistons covering and uncovering said ports and thereby effecting the cylinder valving, the pistons being provided with balls which engage the cams, and the pistons being provided with passages through which the fluid pressure in the cylinder bores is communicated directly to the balls.

VIRGIL D. BARKEB..

(References on following Page) REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date Steinbecker Dee. 1, 1914 Sears Apr. 10, 1917 Hutchinson Nov. 4, 1919 Weingartner Mar. 29, 1927 De Leeuw May 15, 1928 Bedford Nov. 27, 1934 De Stoutz Nov. 17, 1936 Ginn Nov. 24, 1936 Whitcomb Feb. 23, 1937 Number Number Name Date Zimmerman Jan. 28, 1941 Treer Dec. 30, 1941 Williams Mar. 10, 1942 Holmes Dec. 11, 1945 Huber Dec. 25, 1945 Smith Mar. 11, 1947 Parilla et al Oct. 14, 1947 Deschamps Dec. 2, 1947 FOREIGN PATENTS Country Date Great Britain Mar. 2'7, 1930 France 1927 France Oct. 9, 1939

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