US2977891A - High pressure radial piston pump - Google Patents

Description

April 4, 1961 A. E. BISHOP 2,977,891

HIGH PRESSURE RADIAL PISTON PUMP Filed Oct. 29, 1956 7 Sheets-Sheet 1 April 4, 1961 A. E. BISHOP 2,977,891

HIGH PRESSURE RADIAL PISTON PUMP Filed Oct. 29, 1956 '7 Sheets-Sheet 2 April 4, 1961 A. E. BlsHoP 2,977,891

HIGH PRESSURE RADIAL PIsToN PUMP Filed oct. 29, 195e 7 sheets-sheet s April 4, 1961 A. E. BISHOP HIGH PRESSURE RADIAL PISTON PUMP Filed Oct. 29, 1956 7 Sheets-Sheet 4 April 4, 1961 A. E. BISHOP 2,977,891

HIGH PRESSURE RADIAL PISTON PUMP Filed Oct. 29. 1956 ,7774 Ex I April 4, 1961 A. E. BISHOP HIGH PRESSURE RADIAL PIsToN PUMP 7 Sheets-Sheet 6 Filed Oct. 29. 1956 April 4, 1961 A. E. BISHOP HIGH PRESSURE RADIAL PISTON PUMP Filed Oct. 29, 1956 5 s BDU L IN VEN TOR. H/Z-J/f" E EZ sajf.

HIGH PRESSURE RADIAL PrsroN PUMP Arthur E. Bishop, Detroit, Mich. (12 Millwood Ave., Chatswood, New South Wales, Australia) Filed Oct. 29, 1956, Ser. No. 619,062

V22 Claims. (Cl, 1031-161) rThis invention relates to a high pressure radial piston pump or motor having a rotor embodying a plurality of pistons, in radial cylinders, and a piston drive system, the rotor and the piston drive system riding on antifriction bearings within a chamber or housing.

It is the general object of the invention to provide an improved pump or motor yof the class stated above capable of operating at high speeds and yet of simpler and cheaper construction than heretofore known.

Another object of the invention is to provide a pump of the above stated class having las far as possible rolling contact at all moving parts of high load intensity, thereby minimizing the tendency to gall or seize, which is a chief problem in he operation of pumps at high temperatures or when using fluids of low lubricity.

Another object of the invention is to Y-provide a pump of the above stated class in which the loads act on the rotor-so that the latter may be adequately journalled by a single large capacity angular contact ball bearing axially displaced toward the driven end of the rotor from the plane of the pistons.

Another object of the invention is to provide a high pressure radial piston pump wherein the rotor is journalled by a single ball bearing placed to one side of the load plane of the pistons, thus leaving clear the opposite end face of the rotor to provide space for an adequately large valve plate for commutating fluid flow to and from the rotor; such an arrangement contributes materially to the optimum performance of the pump at low inlet pressures such as may be experienced at high altitude in aircraft or missiles.

Another object of the invention is to provide a pump wherein the stationaryV pump housing is machined to provide integrally therein two respectively eccentric raceways for anti-friction bearings carrying respectively the rotor and piston drive system, said housing being enclosed by an end cap embodying inlet and outlet connections for the pumping fluid.

A still further object of the invention is to provide a high pressure pump embodying a flat valve port plate for commutation of fluid flow to and from the rotor, said valve plate being positioned typically several ten thousandths of an inch clear of the flat end face of the rotor during operation of the pump to provide virtual sealing therebetween without physical contact, and a piston or system of pistons, acting on said plate `responsive to the quantity of leakage fluid flow between said flat faces to maintain said clearance.

Various other objects, features and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, illustrated presently by the preferred embodiments thereof and wherein:

Figure l is a transverse section through a unit constructed according to Vthis invention, with the valve'plate and end cap shown in elevation;

Figure 2 is a perspective view showing the radial type roller cage;

arentY Figure 3 is a cross-section on a reduced scale through the pump taken on line III-III of Figure l;

Figure 4 is an end elevation on a reduced scale of the pump showing the fluid inlet and outlet means;

Figure 5 is a fragmentary cross-section through the pump and the valve plate taken on line V-V of Figure 4;

Figure 6 is a schematic diagram on an enlarged scale showing the ve pump pistons, the radial roller cage and rollers in various locations during the rotation of the rotor through 360;

Figure 7 is a perspective view of an alternate form of pump rotor and radial type roller cage with the associated parts in operating position;

Figure 8 is a fragmentary perspective view of the radial roller cage with rollers arranged therein as shown in Figure 7;

Figure 9 is a fragmentary vertical section with parts in full, taken longitudinally through a modified type of pump embodying the present invention, the rotor embodying flange portions and cage rings;

Figure 10 is a sectional view taken on the plane indicated by the line X-X of Figure 9;

Figure ll is a fragmentary Vertical sectional View Similar to Figure 9, showing an alternate construction;

Figure l2 is an end view showing the face of the Valve plate and the associated parts of the modification shown in Figure ll;

Figure 13 is a fragmentary, enlarged View of a portion of Figure ll; and

Figure 14 is a perspective view of the valve plate with weep grooves and associated openings. p

Referring to Figures l through 14, a pump constructed according to this invention generally comprises a hous- Ving 20 having a removable adaptor 21, a rotor 22 having a bank of live cylindrical pistons 24, 25, 26, 27 and 2S, operatively assembled in cylinders 3l), 31, 32, 33 and 34, an end cap 35 provided with a fluid inlet passage, open- 'ing or connection 36 and a fluid outlet passage, opening or connection 37, a balanced port plate 38, a ball bearing 39, a roller bearing 40, and `a radial cage 4l supporting a plurality of rollers 42.

The rotor 22 is journalled by the bearing 39 in the housing 2i) to rotate about a center 45 and is provided with a series of arcuate grooves 47 lin its periphery, one groove located between each of said cylinders 30, 31, 32, 33 `and 34, said cylinders being arranged generally radial with respect to the axis 45 of said rotor 22; shown by Figure 3. The rear hu-b portion 50 of the rotor 22 is bored out -to receive and have assembled therein a drive lug 5l which is slotted to receive the driving extension 52 on the end of the drive shaft 53. Thefree end of the rotor 22 is provided with an end face 54 and with five arcuate shaped openings 55, S6, 57, 58 and 59 to provide passageways for the Huid being pumped. Said passageways 55 through 59 extend from t-he face 54 of the rotor to the chambers 6l, 62, 63, 64 and 65 formed in the roto-r beneath each of the cylinders 30 through 34. The exterior surface of the rotor is further provided with circular grooves 66 and 67 for reasons to be explained later.

The ball bearing 39, embodying a plurality of balls 70, is assembled between a race-way 69 on the inner surface of housing 2li and an inner race-way 63 formed in the rotor 22 at the rear end of said housing.

The roller bearing 4G, embodying a plurality of rollers 72, is assembled within said housing Ztl in a plane extending through the radial center line of the cylinders and is eccentrically disposed relative to bearing 39. An inner cylindrical surface of housing 20 forms the outer race of bearing 4l).

The radial cage v41 and the plurality of rollers 42 are assembled between the inner race 43 of said roller bearing 40 and the rotor 22. The cage 41 is constructed of two circular rings or discs 73 and 74; ring 74 is constructed and provides for a plurality of drive members and spacing bars 75 with locking end portions 76 for interlocking with a notch 77 in the inner edge portions 78 formed upon the inner periphery of the ring 73. As clearly shown by Figure 2 each ring is provided with a plurality of radial extensions S having elongated slots or radially extending guides 79 having parallel sides'. A pair of oppositely disposed and aligned slots 79 is provided for guiding each roller 42 and for holding same in its proper position. Said grooves 66 and 67 in the rotor provide clearance for the radial extensions S0 of the rings 73 and 74 during the running engagement with the rotor. There are live bars 75, each arranged to extend into a groove, slot or notch 47 of the rotor 22, whereby the cage is caused to rotate with the rotor 22 about a center 44 midway between the rotor center 45 and the race center 46. The flange portion S2 of the ring 74 is journalled loosely in the circular recess 81 formed in housing 20 about the center 44.

The rotor 22 and the inner bearing race 43 are relatively disposed so that the inner periphery of the bearing race 43 and the path of rotation defined by the outer periphery of the rotor 22 are closely spaced at one point a distance substantially less than the diameter of one of the rollers 42. The periphery of the rotor 22 is provided with a series of spaced axially extending slots 47 intersecting the cylinders so as to accommodate the rollers 42 in their movement past said point upon rotation of said rotor 22. The slots 47 in the periphery of the rotor 22 which intersect the cylinders leave opposed cylindrical wall segments straddling each such slot, thus providing bearing support for the pistons to the outer periphery of the rotor 22 while at the same time permitting each roller 42 in itsl excursion to move between the opposed cylindrical wall segments of the cylinder.

The valve plate 38, clearly shown by Figure 5, is arranged substantially in a xed rotary position but with limited axial movement in the end cap 35 and can be substantially defined as a balanced valve plate. Said valve plate is maintained in oil sealing contact with the end 54 of the rotor, but without unnecessarily high contact pressure. A spring 85 is positioned between the valve plate 38 and a washer 86 to bias the valve plate towards the rotor 22. As any of the pistons move radially outwardly and recede from the bottom of one of the cylinders, iuid will flow through inlet 36, through openings or passages 88 (in the end cap) and 89 in the valve plate, through an opening such as 55 and into one of its associated cylinders such as 30. As the piston is driven downwardly into its cylinder, it forces the fluid out through one of the passageways as 55 to port or passage 90 in the valve plate 38. As best shown by Figure 5, the valve plate 38 is tted with a piston 91 iitted in a cylinder 92 which is adapted to be connected with one side of outlet 37 by means of channel 93. The piston 91 has a bore formed therein communicating with port passage 90 in the valve plate. The valve plate is urged towards the end of the rotor 22 by the helical spring 85 arranged in the bore of said piston 91, one end of said spring pressing against the plate 38 and the other end of the spring pressing against the washer 86. Therefore, high pressure fluid is forced through outlet 37 located in the end cap 35. The valve plate 38 is acted on by high pressure oil being discharged from passageway 55 of the rotor 22, shown by Figure 5, and would be driven away from sealing engagement with the end face of the rotor were it not for the presence of the balance piston 91 formed integral with the valve plate 38. Oil contained in the discharge channel 93 acts on the annular rear face of the piston 91 and maintains the valve plate in liquid sealing engagement with the end face 54 of the rotor 22 in accordance with a well known principle in the art termed balanced valve plate. A pin 123 secured in the end cap 35 projects into a hole 124 in port plate 38 and prevents rotation of the valve plate 38 with the rotor 22.

The operation of the above pump may be explained as follows. The rotor 22 is journalled in housing 20 to rotate about center 45, the roller bearing 4) is also journalled directly in the housing but rotates about center 46. In practice it may be shown that despite small disturbances these members rotate at substantially uniform speed about their respective centers. Now considering the rotor 22 as stationary in order to more readily understand the motions of the respective parts, it follows that the roller bearing 40 describes a circular path about the center 45 of the rotor 22 but without rotation thereabouts, thereby causing the reciprocation of a piston in a cylinder within the rotor a distance substantially equal to twice the distance between centers 45 and 46. It is a well known principle that a roller between two surfaces which move in relation to each other will tend to move relative to each surface half the relative movement between the respective surfaces. 'll1erefore,it follows that with a cylindrical roller 42 interposed between the inner race 43 of roller bearing 40 and one end of each piston, with respect to the now fixed rotor, the rollers 42 will each follow a substantially elliptical path having a major axis equal to twice the minor axis. It may be shown geometrically that a third member rotating substantially at uniform speed about another center 44 half the way between centers 45 and 46 has the property that, with respect to this latter member, the rollers will have a radial reciprocatory travel in a substantially straight line. We therefore construct and arrange cage member 41 to revolve in housing 20 about center 44 having close fitting guide slots 79, which will effectively prevent rollers 42 becoming misaligned or moving out of their desired path of travel and yet satisfy the required motion of the roller. If the radial load due to pressure under piston 24 were the same during 360 rotation of the rotor 22, it would follow that the ellipse of the motion of the rollers 42 would be symmetrical with the piston axis and radial to the center 45 of the rotor. In practice, as a load during the pumping stroke is many times as great as that during the intake stroke, and the drag required to drive the roller bearing race 43 must be provided by frictional contact between the roller 42, piston Z4, and the inner race 43 of roller bearing 40, the pistons 24 must be offset a distance O from the rotor center 4S and the slots 79 of the cage 41 must be offset approximately half this distance as at C. In this way thevoverturning tendency of the piston in its cylinder during the pumping stroke is minimized and in consequence the Wear of a cylinder bore is at a minimum. This is illustrated in Figure 6 by the fact that the rollers shown on the left side of the vertical center line of the drawing which shows the pumping stroke are offset a very minimum distance compared with the relatively large offsets shown during the intake half of the cylinder shown in the drawing to the right of the vertical center line thereof.

In order to maintain at all times' the desired relationship between roller 42 and the piston 24 and in particular to insure that the pumping load is taken up by the piston 24, as shown at the top position in Figure 6, the cage is provided with a geared engagement with rotor 22 consisting of five arcuate slots 47 intermediately placed between the cylinders in the rotor 22 for the driving means comprising bars 75 of cage member 41. A guide or bearing system for the cage 41 is provided to insurc rotation about center 44 and is provided by cylindrical recess 81 in housing 20 in which the ange 82 of the cage 41 is loosely journalled. During a normal running of the pump the cage ange 82 does not touch the surface defining the recess 81 and the cage is fully supported by the five rollers 42. The construction shown in Figures l-8 is preferred for high speed applications.

An alternate equivalent construction of the cage and rotor is shown in Figures 7 and 8. ln this construction Iii" vll all the desired driving relationship between the cage 241 and lthe rotor 222 is maintained by geared engagement of arcuate slots 247 which in their construction are formed in radial alignment with the cylinders rather than in midspacing arrangement as shown in Figure 3. In this construction alternate slots 24S are relieved so as not to engage yspacing bars 275 formed on cage member 241. The rollers 107 are provided with integral trunnions 108 engaging the parallel sided guide slots 110 of cage 241 shown by Figure 8. Extensions 112 arev made of enlarged radius and engage the arcuate slots 247 of rotor 222 and therefore provide the geared engagement as required for the correct timing of the cage system. Cage 241 preferably is journalled for rotation about center 44.

A further alternative construction of cage and guide system is shown in Figure 9 and which is suitable for less critical applications. In this construction the rotor .22 is flanged on one side to form cage-ring 114, and with Va cage-ring 115 assembled on the other side of the roller bearing. Both the cage-rings are formedv with a series of aligned elliptical slots 116 of such a shape as to accommodate the elliptical travel of the rollers 42 illus'- trated in Figure 10. With this arrangement the roller is prevented from skewing only at the extremes of radial travel and not in the positive manner of the previous cage arrangements but would sufce for simpler and cheaper pumps.

Figures ll, 12, 13 and 14 illustrate an improved type of valve plate construction which is preferred for critical high speed, high temperature applications. During the rotation of the rotor 22 there is a tendency for the valve plate 38 to rock from side to side due to the fact that the center of pressure of oil escaping from the passage in the rotor moves from side to side as well as changing its effective radius from the rotor center line, However accurately the valve plate is balanced, such balance must necessarily be a compromise because of this rocking action. This results in the engagement of the valve plate with the rotor face alternating between a high intensity of pressure and a relatively large gap or leakage path. In developing pumps for high temperature `or for use with iluid of marginal lubricity such as silicone fluids, it is not practical to have sliding faces in contact at high surface speeds and high intensity of loads. Such brief period of high intensityA of load as previously referred to causes the valve plate t bind or gall in its contact with the rotor face. The presently described valve plate is constructed and arranged relative to the end face of the rotor to maintain a slight clearance within close limits between the valve plate and the rotor face of typically several ten-thousandths of an inch irrespective of the fact that the rotor may be running out of true several thousandths due to eccentricity of the bearing race or for other causes, thus permitting leakage of uid from the discharge side of the pump through such clearance. Such an` arrangement cornprises an extremely responsive servo mechanism including a piston system capable of sensing the How of uid through such clearance from the high pressure lluid in the discharge port radially outwards toward the low pressure area in the housing. 1n Figure 1l is shown a servo valve plate setup generally similar to that shown in Figure 5. The balanced piston 140 is generally made substantially smaller than previously and would unaided fail to keep the valve plate in operative sealing engagement with the rotor. One or more supplementary pistons 141, shown dotted in Figure 12, are therefore arranged around the balanced piston and will normally be acted on by a pressure of the fluid in the clearance between the valve plate and the end face of the rotor intermediate between the high pressure oil and the low pressure oily in the housing. This pressure will continually fluctuate in order to continually position the valve plate in the desired clearance position with respect to the rotor. For example, in Figure 13 oil escaping through the fine clearance 150 will lose some pressure as it flows radially outwards into a low pressure area such as collection gutter 151 and will'lose further pressure as it ilows radially outwards into the housing as at 152.

The clearance 150 normally is such as to permit a leakage of the order of not more than 1-5% of pump output, preferably the smaller the better, but sufficient to prevent engagement of the valve plate with the rotor end face.

The drop of pressure along the line clearance 151) would be approximately proportional to the distance along the flow path in a manner analogous to the loss of head with distance in a pipe. Thus, irrespective of the clearance, the pressure in collection gutter 151 would always be roughly intermediate between the high pressure passage, typically 3000 p./sq. in. and the housing pressure, typically 30 p./sq. in. Thus, the pressure 0f oil in connecting passage 153, in chamber 154, and acting on piston 141 would remain substantially uniform. However, -with a leakage path or groove 156 between gutter 151 and a low pressure area in the case, the pressure in gutter 151 will more nearly approximate that of the case--that is, typically 300 p./sq. in. Suppose that, due to some disturbance, the clearance as at 150 increases from thedesired clearance by several ten-thousandths of an inch; it will follow that the total quantity of oil iiowing through clearance 150 between the rotor 22 and the valve plate will greatly increase, whereas the quantity flowing through the groove 156, for the same pressure difference, would be unaltered. It will follow that the pressure in the collection gutter 151 will` rise and will now much more nearly approach av value intermediate between the high pressure passages and the housing-that is, typically 1200 p./sq. in. Oil ilowing through passage 153 acting on supplementary piston 141 Will virtually instantaneously act on the valve plate to move the valve plate back towards the position it occupied prior to the disturbance. Conversely, if a disturbance causes the clearance 154) to decrease, it will follow that the total quantity of iluid flowing through clearance 150 will decrease and the pressure of oil in gutter 151 will much more nearly approximate the low pressure in the case. This lower pressure in passage 153 and acting behind piston 141 will cause a drop in the total force reacting on the valve plate 33, and it will follow that the valve plate will move away again towards the desired normal clearance position.

In Figure l2 an arrangement of three such supplementary pistons 141 is illustrated surrounding the main balance piston so that any tendency to rock either to right or left or up and down will be instantly resisted by the valve mechanism. The purpose of providing the grooves 156 directly in the -face of the valve plate as shown in Figure 14 is that such orifices with very small areas tend to plug up unless a means is provided to keep them clean. For example, a drilled hole could servethe same function as the groove 156i, but in practice such a hole would be of the order of .O07 inch in diameter and would therefore readily plug up due to the presence of particles in the pumping fluid. By locating these grooves 156 in the face of the valve plate, they will continually be wipedclean by the action of the rotor 22 running in contact with the valve plate 138.

It will be observed that a novel high pressure displacement pump has been described, the pump embodying a rotor and a plurality of radial pistons Where the piston load is transferred to the inner race of a roller bearing by means of a roller, the roller bearing carrying a direct radial' load produced by the piston when under pressure.

I have built and tested a pump embodying the construction of Figures l-V6, weighing 2.3 pounds, which when operated at a speed of 12,0()0 rpm. delivered 5.9 gallons per minute or oil at 2500 p./sq.` in.

The construction herein disclosed may be used as a motor as well as a pump, and therefore in using the term 7 pump I desire that it shall not exclude motor use unless expressly indicated.

I have, in the drawings and specification, presented a detailed disclosure of the preferred embodiments of my invention, but it is to be understood that I do not intend to limit the invention to the specific form disclosed but intend to cover all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by my invention.

I claim:

l. A pump comprising a rotor provided with a plurality of radially extending cylinders and a piston reciprocably arranged in each cylinder, a bearing having an annular race surrounding said rotor, said rotor and race being arranged for rotation about spaced parallel axes, a plurality of rollers, one disposed between and in rolling contact with one end of each piston and said race and transmitting the thrust therebetween, said rollers being operable for effecting the power stroke of said pistons upon rotation of said rotor, and a rotary cage arranged to revolve with said rotor about a center other than that of said race and operable for positioning said rollers between the ends of said pistons and said race.

2. A pump according to claim l wherein said cage is arranged to. rotate about an axis disposed between the Y axes of rotation of said rotor race.

3. A pump according to claim l wherein said cage is provided with a series of pairs of radially extending guides, each pair of guides cooperating with the ends of a roller for guiding the same in its rolling movement between the end of a piston and said race.

4. A pump according to claim l wherein said cage is arranged to rotate about an axis midway between the axes of said rotor and race.

5. A pump comprising a rotor provided with a plurality of radially extending cylinders and a piston reciprocably arranged in each cylinder, a bearing having an annular race surrounding said rotor, said rotor and race being arranged for rotation about spaced parallel axes, a plurality of rollers, only one disposed between and in rolling Contact with one end of each piston and said race and transmitting the thrust therebetween, said rollers being operable for effecting the power stroke of Vsaid pistons upon `rotation of said rotor, and a rotary cage arranged to revolve with said rotor and operable for positioning said rollers between the ends of said pistous and said race.

6. A pump according to claim wherein said cage is arranged to rotate about an axis midway between the axes of said rotor and race.

7. A pump according to claim 5 wherein said annular race is the inner bearing race and wherein the outer bearing race forms at least part of the pump housing.

S. A pump according to claim 5 wherein the outer periphery of said rotor is provided with axially extending slots and wherein parts of said cage project into said slots for effecting the rotation of said cage with said rotor.

9. A pump comprising a rotor provided with a plurality of radially extending cylinders and a piston reciprocably arranged in each cylinder, a bearing having an inner annular race surrounding said rotor, said rotor and race being arranged for rotation about spaced paral- .lel axes, a plurality of rollers, one disposed between and in rolling contact with one end of each piston and said race and transmitting the thrust therebetween, said rollers being operable for effecting the power stroke of said pistons upon rotation of said rotor, and a rotary cage arranged to revolve with said rotor and operable for positioning said rollers between the ends of said pistons and said race, said cage and rotor having interengaging portions for effecting the rotation of said cage with said rotor, said rotor and said bearing race being relatively disposed so that the outer periphery of said rotor and the inner periphery of said bearing race are closely spaced at one point a distance less than the diameter of one of said rollers, the periphery of said rotor being relieved to accommodate said rollers in their movement past said point upon rotation'of said rotor.

l0. A pump according to claim 9 wherein said cage is mounted for rotation about a center midway between the axes of said race and rotor.

l1. A pump comprising a rotor provided with a plurality of radially extending cylinders and a piston reciprocably arranged in each cylinder, the periphery of said rotor being provided with a series of spaced axially extending slots each of which intersects one of said cylinders in such a way as to leave opposed segments of the walls of said cylinders straddling one of said slots, a bearing having an inner annular race surrounding said rotor, said rotor and race being arranged for rotation about spaced parallel axes, a plurality of rollers, one disposed between and in rolling contact with one end of each piston and said race and transmitting the thrust therebetween, said rollers being operable for effecting the power stroke of said pistons upon rotation of said rotor, and means operable for positioning said rollers between the ends of said pistons and said race, said slots in said rotor permitting a roller in its excursion to move between said opposed cylinder wall segments.

12. A pump according to claim 11 wherein said means comprises a cage arranged to revolve with said rotor, said cage being provided with a series'of guides, each guide cooperating with the ends of a roller forguiding the same in its rolling movement between the end of a piston and a race.

13. A pump according to claim l1 wherein each of said pistons consists of a cylindrical member.

14. A pump comprising a cylindrical housing having two axially spaced bearing races provided on the interior thereof, said races being eccentrically disposed, one of said races formng the outer race of a ball bearing, a rotor journalled in said ball bearing, said rotor being provided with a plurality of radially extending cylinders and a piston reciprocably arranged in each cylinder, said cylinders and pistons being surrounded by the other of said bearing races, which forms the outer race of a roller bearing, the inner race of which surrounds said rotor and is disposed in the plane of said cylinders, a plurality of rollers, one disposed between and in rolling .contact with one end of each piston and said inner bearing race and transmitting the thrust therebetween, a cage arranged to revolve with said rotor and about an axis other than that of said inner bearing race, said cage being operable for positioning said rollers between the ends of said pistons and said race and for guiding said rollers in their rolling movement between the end of a piston and said race.

l5, A pump comprising a cylindrical housing having two axially spaced bearing races on the interior thereof, said races being eccentrically disposed, one of said races forming the outer race of a ball bearing, a rotor journaled in said ball bearing, said rotor being provided with a plurality of radially extending cylinders and a piston reciprocably arranged in each cylinder, said cylinders and pistons being surrounded by the other of said bearing races, which forms the outer race of a roller bearing, the inner race of which surrounds said rotor and is disposed in the plane of said cylinders, a plurality of rollers, one disposed between and in rolling contact with one end of each piston and said inner bearing race and transmitting the thrust therebetween, means for positioning said rollers between said ends of said pistons and said race, said inner bearing race and rotor being relatively disposed so that the path of rotation dened by the outer periphery of said rotor and the inner periphery of said bearing race are closely spaced at one point a distance less than the diameter of one of said rollers, the periphery of said rotor being relieved to accommodate said rollers in their movement past said point upon rotation of said rotor.

16. A pump according to claim 15 wherein each of said pistons consists of a cylindrical member.

17. A pump according to claim 15 wherein said rotor is provided with an end face remote from said ball bearing and Huid passageways between said end face and said cylinders, and wherein a nonrotatable valve plate is operatively disposed adjacent said rotor end face and is provided with iluid inlet and discharge passages adapted to register with the passageways in said rotor upon rotation thereof.

18. A pump comprising a cylindricalhousing having a bearing race provided on the interior thereof, a rotor journaled in said housing for rotation about a center offset `from that of said bearing race, said rotor being provided with a plurality of radially extending cylinders and a piston reciprocably arranged in each cylinder, said cylinders and pistons being surrounded by said bearing race, which forms the outer race of a roller bearing, the inner race of which surrounds said rotor and is disposed in the plane of said cylinders, a plurality of rollers, one disposed between and in rolling contact with one end of each piston and said inner bearing race and transmitlting the .thrust therebetween, means for positioning said rollers between said ends of said pistons and said race, said inner bearing race and rotor being relatively disposed so that the path of rotation dened by the outer periphery of said rotor and the inner periphery of said inner bearing race are closely spaced at one point a distance less than the diameter of one of said rollers, the periphery of said rotor being relieved to accommodate said rollers in their movement past said point upon rotation of said rotor. v

19. A pump according to claim 14 wherein said inner bearing race and rotor are relatively disposed so that the path of rotation defined by the outer periphery of the rotor and the inner periphery of said bearing race are closely spaced at one point a distance less than the diameter of one of said rollers, the peripheryy of said rotor being relieved to accommodate said rollers in their movement past said point upon rotation of said rotor.

20. A high pressure radial piston pump comprising a housing defining a pump chamber, an integral rotor supported by said housing, said rotor being eccentrically positioned in said chamber by a single bearing mounted in said housing, said rotor embodying a plurality of pistons arranged in a plurality of radially positioned cylinders, a lroller bearing within said housing, a roller riding on the inner race of said roller bearing and on one end of each of said pistons, inlet and discharge iluid connections in the housing and communicating with the interior thereof, passageways connecting said cylinders with one end of said rotor, and a control valve plate with a plurality of openings therein for conveying and controlling uid flow to and from said passageways with said inlet and outlet connections during -the rotation of said rotor, said valve plate being positioned with regard to said end of said rotor with a small running clearance and assembled to permit axial movement thereof, said valve plate incorporating a piston system responsive to the pressure of the flow of oil through the pump outlet, the pressure of the oil adjacent said piston system and the pressures of the oil in the clearance between the end of the rotor and the valve plate regulating the amount of clearance therebetween during the rotation of said rotor.

21. A pump according to claim l5 wherein said means comprises a cage arranged to revolve with said rotor, and wherein the axis of rotation of said cage is congruent with the axis of rotation of said rotor. Y

22. A pump according to claim 15 wherein said means comprises a cage arranged .to revolve with said rotor, and wherein the axis of rotation of said cage is disposed between the axis of said rotor and the axis of said ballbearing race.

References Cited in the le of this patent Orshansky Apr. 17, 1956

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