US2827859A - Hydraulic pump - Google Patents

Description

E. "V. CRANE HYDRAULIC PUMP March 25, 1958' INVENTOR 3 Sheets-Sheet l EDWARD V.- CRANE FIG. 4 BY 53 ga/J/ Filed July 1, 1954 ATTORNEYS March 25, 1958 E. v. CRANE 4 7,

HYDRAULIC PUMP I Filed July 1. 1954 :s She ets-Sheet 3 n I Klo INVENTOR EDWARD v. CRANE ATTORNEYS HYDRAULIC PUMP Edward V. Crane, Canton, Ohio, assignor to E. W. Bliss Company, Canton, Ohio, a corporation of Delaware Application July 1, 1954, Serial No. 440,824 1 Claim. (Cl. 103-161) This invention relates to piston type rotary hydraulic pumps and more particularly to an improved construction of a high pressure variable delivery reversible pump.

- The type of pump which embodies my invention has a cylinder barrel journalled for rotation about a fixedaxis in the pump frame, the cylinder barrel having a plurality of radial cylinders with their axes inclined at a slight angle to the radii of the barrel, and pistons in the, An annular reaction ring disposed eccentrical-1 cylinders. ly of the axis of rotation of the cylinder barrel engages the outer ends of the pistons and causes them to reciprocate in the cylinders to pump fluid in an hydraulic'systern to which the pump is connected. Ports communicating with the cylinders are located to one side of the cylinder barrel and fluid being pumped flows axially through the ports to and from the cylinders. Thevolume of fluid pumped is varied by adjustment of the dein the frame thereby preventing separation of inlet and outlet valve members and escape of fluid therebetween. A further object is the provision of a reversible pump with an hydraulic system for automatically counterbalancing radial and axial thrust forces regardless of the direction of flow of fluid being pumped. Still another object is the provision of a radial pump with a side ported rotor journaled in relatively inexpensive sleeve bearings. A further object is the provision of an eflicient lubrication system for a pump of the type described.

Other objects of my invention are the provision of a pump with hydraulic control for varying the volume gree of eccentricity of the reaction ring relative to the axis of rotation of the cylinder barrel and the direction of fluid flow is reversed by shifting the reaction ring to the opposite side of that axis.

The large reaction forces developed within high pressure pumps create serious problems of undue and uneven wearing of the bearing surfaces of the reaction ring'andv of the bearings at the journals of the shaft which supports the cylinder barrel. Moreover, location of valve plates at one side of the cylinder barrel causes an axial thrust to be imposed on the cylinder barrel which tends to separate the valve plates and to cause leakage of fluid between them; Roller or ball bearings on theshaft have been used to limit such shifting of the parts but such bearings are expensive and consequently increase the cost.

of the pump. The problem of bearing wear is the more complex in reversible pumps of the type described be cause the direction in which these forces act shifts by 180 when pumping is reversed.

The pump which embodies my invention solves these problems by providing a unique system for counterbalancing the reaction forces in proportion to the magnitude of the thrust on the bearings. More specifically, I provide an hydraulic circuit through which a fraction of the fluid discharged at high pressure from the pump is fed back into the pump hearings to offset or counterbalance the radial thrust load imposed on the bearings. My invention also contemplates means for hydraulically balancing axial thrust on the cylinder barrel to prevent separation of the valve plates and thereby to eliminate'substantial leakage of fluid and to improve the efficiency of thepump. I

A general object of my invention is the provision of an efficient high pressure variable delivery reversible pump with means for counterbalancing radial and axial thrust loads imposed on the running parts in direct proportion to the magnitude of the loads. Another object is the provision of a reversible pump of the type described with novel means for utilizing working pressure of the pump and direction of flow of fluid pumped; the provision of bearing means for the reaction ring with the maximum area of bearing surface providing low unit pressures and minimumwear; the provision of means for hydraulically counterbalancing radial thrust on the reaction ring Wlii'l.

a-force that is radially aligned with the points of contact of the pistons with the reaction ring; the provision of novel means for feeding high pressure counterbalancing fluid to the bearing surfaces of the pump; and the provision of a compact, eflicient high pressure pump that is durable and economical to manufacture.

"These and other'objects of my invention will become apparent from the following description of a preferred ,embodiment thereof reference being had to the accompartying drawings.

Figure 1 1s a central vertical section of the pump taken.

along the axis of rotation of the shaft.

"Figure 2-is a transverse section of the pump taken along the line 2-2 of Figure 1.

" Figure Sis a transverse section showing the rotatable side valve member on the cylinder barrel, the section.

b'eirig-taken'along the line 3-3 of Figure 1.

Figure 4 is a transverse section showing the stationary valve plate carried on the frame, the section being taken along the line 4-4 of Figure 1.

for preventing substantial axial shifting of the rotor Figure 5 is a transverse sectionshowing the details of construction of the bearing for the shaft, the section being taken along the line 5-5 of Figure 1.

Figure 6 is a schematic representation of the hydraulic control circuit of the pump.

A preferred embodiment of my invention is illustrated in the drawings as a pump with a frame comprising a housing 10 to which an end plate 11 is connected by bolts 12 and which has an integral mounting base 13 for anchoring the unit to a suitable support. The housing 10 and end plate 11 are axially spaced at points inwardly'from their peripheries and have enlarged hub portions 14, 15 fitted with sleeve type bearings 16, 17 in which the shaft 18 carrying the rotor or cylinder barrel It is journalled for rotation about the axis A.

The cylinder barrel 19 has a plurality of cylinders Ztt formed therein with each cylinder fitted with a piston 21 for reciprocation in the respective cylinder. In the preferred pump, the cylinder barrel has two rows of cylinders, the cylinders in each row being arranged in an annular series, and each cylinder in one row being axially aligned with a cylinder in the other row to form a pair, see Figure 2. The axes of each pair of axially aligned cylinders are parallel to each other and are inclined in an axial direction to the radius of the cylinder barrel. The inner ends of each pair of cylinders connect to an axially extending crescent shaped recess 22 which communicates through ports at the side of the cylinder barrel alternately with the main ports 24, 25 of the pump.

A plurality, nine as shown, of ports 26, one for each pairof cylinders 20, are formed at equally spaced intervals in a rotatable valve plate 27, see Figure 3, fastened tgthe front, right asviewed, side of the cylinder barrel Patented Mar. 25, 1195sv by screws 28. In juxtaposition with and engaging valve plate 27 is a stationary valve plate 30 see Figure 4 secured by screws 31 to the adjacent hub portion of the housingJO; These plates 27 and-30 have smoothplanar mating side surfaces 27d and Q3021,- respectively, which are hardened; to resist wear. Valve -plate 30 hastwo arcuat'ely shaped and spaced ports 32, 3; with which ports 26 of the rotatable valve platesuccessively register as the cylinder barrel rotatesabout its axis. Port- 32 communicates via passage 34, see Figure 2-,? with the main por t 24, and port 33 connects to the other main awargsea the pumping force to be transmitted by the reaction port 2 5by means of channeI BS, Fluid to be pumped passes into thev pump, for example, throughpor-t 24 and successively through channel 34, port 32 02 valve plate several? of ports 26 0f plate--27 that momentarily are regis ered with port 32, and into corresponding rece'sfsesi22 and-cylinders 26in the cylinderbarrel. As the cylindefbar'rel-rotats' ports H by-thei portions of plate- S Oiintermediate stationary ports 32'; .3'3' and fluid trapped therein is compressed to high pressure by the inward movement of pistons- 21. Whefi rotating ports 26 successively register with staortsana channel 35 arid-main port 25 to the hydraulic circuit outside the pump.

cylinder Barrel I9 r'citates stunt its A within a 26 l are successively "closedcradle 40 supporte'diwithifi the frame of the pump be- 7 tweer'i tlie,liousing'l0 and'the end plate l l, see Figures l arid 2. Cradle Thais acent'ralcylindricalbore 41 wit1ian axis and withiri ivhich the cylinder barrel rotates.

Actuation of the pistons .is caused by eccentric displace meat of they cradle resp to the cylinder barrel. For this purpose the cfadle is' pivct'allysupported on the upper" an of the pump frame by means -of an axially extending pivot pin 4 4 secured in" afi aperture 45 the cradle an joufiialled at its a pesu projecting ehds in embcss'mess 45,47 fdffiied ofi the upper endsor he housing 1 0 and (hid plate 11, respectively;

ni spu-c ent" er the cradle about the axis of pivot pin 44 is enacted 5y aflnrd ifiofof see Figures 1 and 2, with a piston 51 extending through a transverse recess 52 in the lower end of the" cradle and connected thereto by pin 53. Opposite ends or piston 51 are slidably fitted in sleeves55 fastened by snap rings 56 secured in apertures 58 iii the" side walls of the housing. The eccentricity of the crade 40 with respect to the cylinder barrel, that is, adjustment of the'amount of ofiset between the eradl'e and 'eylinder barrel axes B and A is controlled by for g fluid.lint'o either plug 57 against the adjacent end of pisto ri 5 1 and withdrawing an equal 59, 60-connected to the plugs by suitable means such as the mechanism 114, see Figure 6, ,de'sci-ibe"d below.

A bearing sleeve -62 is secured i'iofi-fotatably in bore 41 er the cradle 40 by apsif or side plates 63, see Figure 1, fastened bybolts 64 to the bearin sleeve and frictionally engaging" the .inargifi'al 'side' portions .of a the cradle. The inner surface 66 of sleeve62 is cylindrical and constitutes a bearing surface" for reaction ring 67 which is freely rotatable within tlie sleeve about cradle axis B. A radial pin 6S see Figure 2, press fitted" in a radial aperture 69 in cylinder' b'a'rrel 19 and slidably en gaged in recess 70 in sleeve 62 locksthe cylinder barrel and reaction ring together for rotatioh'jiri uhis'oiaj A slight clearance'isprovided between the side edges ofQth reaction ring and the plates '63 toavoidlrictioiial'dr ag at these places. a

in hollow plugs' 5 cylinder. barrel axis A, andthe inner surface 66 of the amount of fluid from the 'ot'her pliigthrough "conduits rmg serves to eoufierbsnaee this force,

ring to the pistons to move" same inwardly during onehalf a revolution and on theother half revolution per? mit the pistons to move outwardly toydraw fluid into' the cylinders. v s

Recipfocatibn of" the pistons results in uniform variation of the peripheral velocity of outer extremity of each piston which normally would cause sliding action be-,

bevelled surface 74' thereof and causes the piston toroll ratherthan slide; along the reaction surface, the piston rotating initscylinder as it reciprocat'es. tio'narybottorfi port 33, fluid is ejected through these a As a" result of this design; the bevelled heads of the tworows of pistons contaet'limi-te'cl narrow portions of the reaction surface 72-o;1=ing 67 which while desirable from: the standpoint ofieliminating sliding friction results in concentrating pumping forces transmitted by the 're-' sactifori ring tO'lthiS' limited area of the ring surface. In

, through: cradle-axis-B, the other set 76 of corresponding length Being located 6n the opposite side of' that plane. The ends of these grooves are arcu-ately spaced slightly froiii the intersection of horizontal plane Y-'Y,"through beariii'g'sleeve and hence either grooves or grooves 76, dependihg onwhiich side of the neutral or no pump! in position cradle has been adjusted,- extend over that par ies of the reaction ring which forces the pistons porfioriof thlfiuid at' puinp diseha-rge pressure is directed extending passage in the left end, as viewed in Figure l, of QtpiiiM foa conduit 79 which ishydraulically connected as main part 24 of the pump. The other set of the grooves 76 issiniilarly hydraulically connected to the otherl'fiiaifi poft' 25.0f the pump by means of channel seeFigilre 2,1 annular groove 81- on the inner surface 41 of the cradle, channel 82,"passage 83in the right, as viewed in nigufk ljld of pivot pin 44.and conduit 85 which connects directly to port 25i Regardless of the direction in w "611 fluidis' pumped by the pump, that is to say; regs-mess of whether'port 246: port 25 is the high a ressure port for the pump, high pressure fluid will be di The width or the out r stir-face 71 at reassess ring.

62 and hesc'eflie radial tones 6r rescues are distributed over a maximum bearing surface area which resting. in

67 is substantially the same as the width or manage eve action surface againstwliichltheheads 736F 66 istonsagainst J seiner ti rat alignment rected through the. above described passages and channels theprdpe ort the pistgns in th ndefpa'r'r'el. It will befo'tfe th "fluid,.. by this system is directed r ace of "the reaction ring in substam isf't'a'ltetr time the" discharge sneorthe pum counter t'of greevesvs or 76 for counterbalaficing V p a r with the'contactofthe several pistons; whee edsuc ing; Since the fluid for this purpose balancing is effected hydraulically with a force proportional in magnitude to the pumping force and which is applied directly to the portions of the reaction members which transmit this force to the pistons. In addition to this counterbalancing function, the high pressure fluid serves effectively to lubricate the bearing surfaces of sleeve 62 and ring 67 by spreading over these surfaces in a thin film which emanates from the grooves. Lubrication of the inner surface 72 of the reaction ring to minimize friction and wear at the points of contact of the piston heads with the reaction ring is facilitated by several radially formed seep holes 86 in the central portion of the. ring, or, alternatively, by cooling oil circulated between and around the cylinder barrel and reaction ring.

In order to counterbalance the radial thrust imposed on the journals of shaft 18, bearings 16 and 17 are formed with circular peripheral grooves 88, 89 and 90, 91, respectively, see Figures 1 and 5, on opposite sides of the inner surfaces of the bearings for admitting fluid under working pressure to the portion of the bearing surface against which the radial thrust is directed. Channel 92 carries fluid from port 24 of the pump to groove 88 of bearing 16 and a similar channel 93 provides communication between port 25 and groove 89. Each of the peripheral grooves 88 and 89 intersects an axially extending collection groove 88, 89, respectively, located at the trailing end of the peripheral groove, the shaft being rotated in one direction only, counterclockwise as viewed, and about midway of the top and bottom of the bearing. Fluid forces into the bearing under pressure through one peripheral groove is carried between the bearing and the rotating journal surfaces to the collection groove of the other peripheral groove and hence the direction of rotation of shaft 18 determines at which end of the peripheral grooves the axial grooves are located. Fluid gathered by the collection groove passes to the opposite or low pressure inlet port of the pump.

Bearing sleeve 17 is constructed substantially the same as sleeve 16 with a similar pair of grooves 90, 91, shown in broken line in Figure 1, on the inner surface of the sleeve and each communicating with an axial groove, one of which is indicated at 90' in Figure 1. Conduits 95 and 96 connected to ports 24 and 25, respectively, communicate through channels 97, 98 in the end plate 11 with the respective peripheral grooves 90, 91 in bearing 17 and provide supply and return passages forhigh pressure fluid delivered to the bearing in the same manner as in bearing sleeve 16.

When the pump is in operation and the cylinder barrel is pumping fluid at high pressure into the outlet port 24 or 25, as the case may be, axially directed forces developed by the axial flow of fluid through the ports at the side of the cylinder barrel tend to cause the cylinder barrel together with shaft 18 to move slightly rearwardly, that is, to shift to the left as viewed in Figure 1, causing separation of valve plates 27 and 30 and leakage of fluid between them. To prevent this, recess 100 in hub 15 of end plate 11 within which bearing sleeve 17 is located is made longer than the journal of shaft 18 carried therein to provide a space or clearance 100a between the ends of the recess and shaft. Fluid under pressure is introduced into the space 100a through conduit 102 connected to the high pressure port of the pump and through channel 103 in end plate 11 and urges shaft 18 in the manner of a piston forwardly to the right as viewed in Figure 1, a packing seal 104 sealing the interior of bearing 17 against the end plate. The cylinder barrel and valve plate 27 carried on the shaft are likewise urged forwardly and hence valve plates 27 and 30 are pressed tightly together. Conduit 102 is connected to the high pressure or discharge port of the pump and the force which acts against the end of the shaft is directly proportional to the reaction force tending to separate the valve plates, and hence loss of fluid at this point is virtually eliminated even when the pump is working at extremely high pressures. The inner forward edge 30b of valve plate 30 is recessed as shown in Figure 1 to fit over the end of bearing sleeve 16 and to provide an axial bearing area for valve plate 30. This bearing area is adequately lubricated by oil from bearing 16 so that the counter-balancing pressure on the'end of the shaft is taken against a film of oil, thereby preventing scoring due to rubbing at this bearing area.

Figure 6 is a schematic diagram of an hydraulic circuit through which fluid is carried-from the discharge side of the pump to points within the pump for counterbalancing reaction forces developed. Main port 24 is tapped by line 105 which connects to conduit 79, and line 106 is similarly connected between port 25 and conduit 85 to supply fluid underpressure for counterbalancing forces at the periphery of the reaction ring. Lines 107 and 108 connect conduits 95 and 96 with ports 24 and 25, respectively, to supply fluid for counterbalancing radial thrust at the rear, left as viewed in Figure l, shaft journal.

Fluid to balance the axial thrust on the shaft is carried to conduit 102 by line 110 connected to ports 24 and 25,

and through check valves 111 and 112 in lines 107 and Fluid for adjustably operating cradle motor is obtained from a suitable source such as a servo-actuating mechanism, see Figure 6. This mechanism comprises a. pump P driven by motor M and hydraulically connected to opposite ends of cradle motor 50. The line to the small area of piston 51 is directly connected to pump P and hence this end of the piston is under constant pressure. Fluid is admitted to or released fro-m the opposite end of the cradle motor by valve V connected of selective operation to link L. This link is pivotally connected at one end by suitable means to the cradle 40 and registers the position of the cradle by means of a pointer and scale 115 at the opposite end. The link is also connected to a spring centered actuating device 116 by means of which the valve V is actuated to control flow of fluid to or from one end of the cradle motor for positioning the cradle. The servo-actuating mechanism 114 is illustrative of a suitable means for controlling the direction and volume of fluid pumped and does not constitute, per se, a part of my invention.

In describing the operation of the pump, it will be assumed that shaft 18, driven by a suitable motor, causes cylinder barrel 19 to rotate in a counterclockwise direction as viewed in Figure 2, and that cradle 40 is positioned with its axis B offset to the left as viewed in Figure 2 of cylinder barrel axis A. Port 24 then becomes the inlet port and port 25 the discharge port of the pump.

Fluid to be pumped enters port 24, preferably under some pressure, is drawn through port 32 in stationary valve plate 30, through the rotating ports 26 of plate 27 registered with port 32 and into the corresponding recesses 22 and'cylinders 20. It will be noted that pistons 21'move outwardly during substantially the upper half are of revolution of cylinder barrel 19, above line YY of Figure 2, and draw a charge of fluid into the cylinder barrel during this half revolution. On the other half revolution, below line Y-Y, pistons 21 are moved radially inwardly and force the charge through port 33 of stationary valve plate 30 and out discharge port 25.

It will be noted the radial thrust is transmitted to pistons 21 by the portions of cradle 40 and ring 67 which are below line Y-Y. To counterbalance this thrust, a portion of the discharge fluid is transmitted by line 106, see Figure 6, conduit in cradle pivot pin 44, and peripheral groove 81 in the cradle bore, into the pairs of grooves 76 in the face of bearing sleeve 62 over which reaction ring 67, passes. Since grooves 76 are radially aiigned withthe gqi'nts offeontact of the pistons-Marthe ev s tm'eft 'ea afidfitehh ans is 9 t e re forces are developed;

Radtaljthrust is alsobalanced at the ionrnalsgot the shaft. For bearing sleeve 16, see Figure a portion of the fluid from discharge port 25 is carried 'by ci'rannelt93 trompasagesc; communicating port 25', tq'greove 89' in the lo'vv r; portion or hearin sleeve 16; Similarly, hi h pressur fittidis carried to the lower pottionor the rear-hearing 17 from part zsj-"by line 108, see Figure 6, cen-dnit 96, pasls'age 98 'and' into 'groove'9I in the lower aetiontorces ttained at the very points {whet-cf those half or bearingl'i; Thus fluid at; a pressure proportional.

to the radial thrust transmitted by the haft journals-to bearing 16 and 1 73s introduced between-the relativel rt toving surfaces; or the journals and bearings and ne-c tively. ounterbalance the thrust; The fluid spreads as a barrel 18 in the opposite direction, that is, to the right as viewed in Figure}. Port 24 then becomes the discharge port and port 25 the inlet port for the. pump. Thrust forces are imposed onthe' opposite portions of reaction ring 67 and shaft journals of the shaft. Grooves 75 in the" upper half of bearing sleeve Gland corresponding grooves 88 and90 in the shaft bearings, being hydraulically connected toport 2'4, carry fluidat discharge pressure which functions in themanner' described above to counterbalance the radial thrust and to insure proper lubrication of the beating 7 7 Check valves 111 and 1 12 see Figure 6', cause fluid at discharge pressure tohe impressed on the end of shaft '18- regardless of the direction of flow of fluid bein'g' "Iclaimi; 7

In=*a pumpghaving ya frarne and having inlet. and dis-' eha'r'g ports, the combination of 'adriving shaft having" axially spja'ced journals, hearin s for said journals stlp' shaft'for rotation about an axis; one end i of said shaft heingjournallejdflwithin saidf'rjam'e, a c lin: on said shaft and rotatable therewith,'

fi 'i 'fi cylinders arranged" in said cylinder barrel in. annular series, pist'o ins'aid'cylinders,1axial recesses in said shaft seminar-heating wr'tlrsaid cylindersand extending to one" side of the cyiindetbarrel opposite from saidone end of the shaft, arotatable valve plate fixed to said one side of tZHe-CyI-irider-baIIeL and; having ports communicating with saidrces'sejsrespectively, a-stah'onary valve plate caffied'on said frame-juxtaposed with "saidrotatablc valve metrically op osed arc-uately elongated ports eothmunicatnigwith said pump inlet and dischargefports, respectively,'a cradlesupported for pivplate and'having a-p'airof otal'movcrneht about an axis, a reaction ring rotatably supported in said cradle and circirmscribi'ng said cylinder barrel, saidcradie together with said ring being adjustable'to positions eccentric to said'cylinder barrel, con nec'ting means between said cylinder barrel and said reaction rin'g'adapte'd' to rotate said cylinder barrelan'd said reaction ring -in ttnison, said ring having an inner surface engage'able withsaid pistons and causing same tomove inwardly during one half revolution of the cylinder-barrel and permittingsa'id pistons to move outwardly during the other'h-alf revolutionof the cylinder barrel whereby to pum fluid, means; for hydraulically counterbalancing radial thrust on said jonrnal bearings and on said r'eac ti'orr r ing 'a'ii'daxial thriist' on said cylinder barrel compris inggroove means between said cradle and said reaction rtngi hy anti" 113 onnected toth'e pum'pdischarge port, said s extendingless than 180 over the poring the pumping cycle, a groove b tween each'jo'urnal pumped. When fluid is discharged from main port 25,

valve 111 is" closed and valve 112 is open to admit fluid at discharge pressure to line 110 and into space 100d at the rear end of the shaft. When port 24 becomesthe discharge port uponr'eversal of direction of fluid'fiow, valve 112' is closed and valve 111 is open so that line 110 still carries fluid at discharge pressure. 7 space 100a within rear journal bearing 17 always is" filled with fluid from the discharge port whenv the pump is operating, and shaft 18, cylinder barrel I9 and valve plate 27 are urged forwardly in opposition to the axial thrust on these parts and valve plates 27 "and 30 are Thus the pressedtogether tightly to make'an efiicien't' leak proof running seal at their respective ports. 7

Changes in and modifications tothe above described embodiment of my invention :may occur tothosehkille'd in the-art withoutdeparting from the principles and scope of the invention, and therefore I do not wish this patent to be; limited precisely to the: embodiment described.

The scope of the patent is defined in the appended claim.

and corresponding 'j' ount-al' hearing hydraulic lly; connected to said rime discharge port, e'ac'hfof said grooves V extendingov'e'r' tlie'portion of the journal which transmits the'radial th asttoree tothe bearingand'cir'c'tiit means hydraulically conneet'iiig said one end of the shaft to said discharge port -for' 'dir-iecting fluid at pump discharge pres sure againsts'ai one end of the shaftto urge said shaft and cylinder barrel to move axially in' the direction for pressing said valve plates 1 together.

7 References Cited in the file of this patent UNITED STATES PATENTS which forces said pistons inwardly dure

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