US2273468A

US2273468A - Hydrodynamic machine

Info

Publication number: US2273468A
Application number: US300353A
Authority: US
Inventors: Ferris Walter
Original assignee: Oilgear Co
Current assignee: Oilgear Co
Priority date: 1939-10-20
Filing date: 1939-10-20
Publication date: 1942-02-17
Anticipated expiration: 1959-02-17

Description

Feb. 17, 1942. w. FERRIS 2,273,468

- HYDRODYNAMIC MACHINE Filed Oct. 20, 19:59 6 Sheets-Sheet 2 INVENTOR. WALTER FERRIS BY l HYDRODYNAMIC MACHINE Filed Oct. 20. 1939 6 Sheets$heet 3 INVENTOR.

WALTER FER Rls BY W 14 r mmvsk' Patented Feb. 17, 1942 HYDRODYNAMIC MACHINE Walter Ferris, Milwaukee,-Wis., assignor to The Oilgear Company, Milwaukee, Wis, a corporation of Wisconsin Application October 20, 1939, Serial No. 300,353

(01. 1os 1s1) 9 Claims.

This invention relates to hydrodynamic machines of the type which will function as pumps when driven mechanically and will function as motors when supplied with motive liquid. Since the same machine will function as either a pump oras a motor, the invention will be explained as applied to a pump but it is to be understood that the invention is equally applicable to a motor.

The type of pump in which the invention is ordinarily embodied has a plurality of pistons fitted in cylinders which are arranged in a rotatable cylinder barrel either directly upon or at a small angle to the radii thereof and the outer ends ofthe pistons engage an annular reaction surface which is arranged around the cylinder barrel, the axis of the reaction surface being offset from the axis of the'cylinder barrel when the pump is delivering liquid.

The cylinder barrel has ordinarily been jour-' naled upon a valve shaft or pintle having passages extending therethrough-and twoports formed therein diametrically opposite each other for conveying liquid to and from the cylinders which communicate with the two ports alternately as the cylinder barrel rotates so that the pintle coacts with the cylinder barrel to form' the main valve.

The pintle ordinarily constitutes the sole support for the cylinder vides the sole reaction that an increase in pump pressure causes more or less deflection of the pintle.

Such a machine has as an inherent characteristic thereof a small amount of slip or leakage which consists in part of liquid that escapes from the high pressure pintle port and spreads over the surface of the pintle to form a lubricating film barrel and therefore profor the pumping forces so' between it and the inner surface of the cylinder barrel. A part of this liquid flows into the low pressure pintle port and a from the ends of the ducing the efficiency part thereof escapes cylinder barrel, thereby reof the machine.

The cylinder barrel is ordinarily closely fitted upon the pintle and one part of the lubricating film adheres to the inner surface thereof and another part of the film adheres to the pintle so that rotation of the cylinder barrel causes shearing of the film. That is, the inner part of the film remains stationary and the outer part moves with the cylinder barrel so that the two partsof the film are constantly being split during rotation of the cylinder barrel. It has been found that shearing the film consumes a substantial part of the power required to rotate the cylinder barrel, thereby further reducing the efficiency ofthe machine.

It has been found in practice that, when a cylinder barrel fitted upon a pintle as above described is run very slowly under a substantial load, the lubricating film between the cylinder barrel and the pintle is not properly maintained and the frictional drag is materially increased. If rotationceases when the cylinder barrel is under pressure, as when a motor stalls under its load, the film may be entirely squeezed out and cause the cylinder barrel to grip the pintle and prevent the machine from delivering any useful torque.

The present invention has as an object to provide a rotary hydrodynamic machine having greater efiiciency than the prior machines.

Another object is to reduce the slip which is inherent in all hydrodynamic machines.

Another object is to provide a radial hydrodynamic machine in which the deflection of the partsis less than in the prior machines.'

Another object is to provide a hydrodynamic machine having a valving mechanism which will enable it when functioning as a motor to deliver its full torque at all speeds and when stalled.

Another object is toprovide a radial hydrodynamic machine which is more compact than the prior machines.

Other objects and advantages will appear from the description hereinafter given of hydrodynamic machines in which the invention is embodied. 7

According to the invention in its general aspect and as ordinarily embodied in practice, a hydro-' dynamic machine is provided with a rotatable cylinder barrel having a plurality of cylinders formed therein and communicating with passages extending through a face formed upon or near the end of the cylinder barrel, a piston fitted in each cylinder, means for reciprocating the pistons in response to rotation of the cylinder barrel, a valve member or seat having upon one end thereof a surface complementary tosaid face and adapted to form therewith a substantially fluid tight joint, a port formed insaid face at one side of the cylinder barrelaxis for connecting said machine to an external circuit and adapted to have said passages register therewith successively as said cylinder barrel rotates so that the liquid in said port is under a pressurewhich tends to valve member and said cylinder liquid in the valve port and between the valve member and the cylinder barrel and which tend to separate the valve member and the cylinder barrel are opposed by a plurality of forces which are exerted by hold-up devices and whose resuit- .means are provided to exert upon the cylinder barrel a force which is proportional to the pressure in the valve port and opposite to the force which holds the valve member against the cyllnder barrel to thereby relieve the bearings of at least a part of the thrust imposed thereon.

According to the invention in another aspect, the valve seat is so supported that it may move transversely of the cylinder barrel axis and thereby prevent annular grooves from being worn in its face or in the end of the cylinder barrel.

The invention is exemplified by the pumps shown somewhat schematically in the accompanying drawings in which the views are as follows:

Fig. 1 is a vertical longitudinal section through a pump in which the invention is embodied, the section being taken on the irregular line l-l of Fig. 3 and certain parts being shown in full.

Fig. 2 is a sectional plan view taken on the irregular line 2-2 of Fig. l and with certain parts shown in full.

Fig. 3 is a transverse section taken on the irregular line 3-3 of Fig. 1.

Fig. 4 is a transverse vertical section taken on a line 3- of Fig. l.

Fig. 5 is an end view on a larger scale of the valve seat shown in Figs. 1 to 4.

Fig. 6 is a central longitudinal section through a pump which difiers from the pump shown in Fig. l in that it is larger, its pistons and cylinders are radial and it is provided with diflerent means for holding the valve member against the end of the cylinder barrel and with means for relieving the thrust on the cylinder barrel bearings.

Fig. '7 is a transverse section taken on a line 1-1 of Fig. 6.

Fig. 8 is a transverse section taken on the line 8-8 of Fig. 6.

Fig. 9 is a view on a larger scale showing the valve member and the rear casing head removed from the casing, the view being taken in the direction of the arrows 8-9 on Fig. 6.

Fig. 10 is a longitudinal section through the valve member and the rear casing head taken on the line lO-Ifl of Fig. 9.

Fig.'ll is a partial longitudinal section through a pump which is similar to the pump shown in Fig. 6 and in which the axial components of the pumping forces are utilized to relieve the thruston the cylinder barrel bearings.

Fig. 12 is a view similar to Fig. l0 but showing a different type of hold-up motor for urging the valve member against the end of the cylinder barrel.

The invention may be embodied in any radial type pump and in some pumps of the axial type but, for the purpose of illustration, it has been shown embodied in a pump of the type in which the pistons and cylinders are arranged in a cylinder barrel at an angle to the axis thereof and the outer ends of the pistons engage an annular reaction surface which is eccentric to the cylinder barrel and makes contact. with each piston upon a single spot ofiset from the piston axis so that rotation of the cylinder barrel causes each piston to reciprocate and rotate in its cylinder. Since this type of pump is fully illustrated and described in latents Nos. 2,074,068 and 2,105,454, only so much of each pump has been shown as is necessary to an understanding of the present invention.

Figs. 1 t0 5 The pump shown in these figures has its mechanism arranged within a casing I which provided with a separable

front head

2 and 21 separable rear head 3. Casing i has a cylinder barrel l rotatably supported therein by means of two bearings either or both of which may be capable oi preventing cylinder barrel i from being moved axially by the pressure created by the pump and which have been shown as a ball bearing 5 and a thrust bearing 6.

Bearing 5 is carried by casing I and fitted upon a hollow huh I which is formed upon the rear end of cylinder barrel l. Bearing 6 is carried by front head 2 and fitted upon a hub 8 which is formed upon the front end of cylinder barrel 4 a and has a shaft 8 fixed thereto and extending outward through front head 2 for connection to a suitable source of power.

Cylinder barrel 4 has a plurality of radial cyl-,

inders in formed therein and a piston H fitted in each cylinder and extending beyond the periphery of cylinder barrel l, the pistons and cylinders being slightly inclined to the axis of the cylinder barrel. While the number of cylinders may be varied to vary the volumetric capacity of the pump, cylinders 10 have been shown arranged in five equally spaced axial rows of two cylinders each.

The cylinders in each row communicate with a passage l2 formed in cylinder barrel 4 and extending rearward through a face H which is formed upon the rear end of cylinder barrel 4 exactly at right angles to the axis thereof and which forms a substantially fluid tight joint with a non-rotatable valve member or seat l4. Hub 'I may be solid and have face I! formed upon its rear end but it has been shown as being hollow and extending around lace l3 and valve seat l4 has been shown as having the front part thereof cylindrical and arranged within huh I in order to reduce the overall length of the pump and to reduce the compression slip, that is. to reduce the amount of liquid that is compressed during one half-revolution of the cylinder barrel and expands during the other half-revolution.

The rear end of each passage l2 constitutes a cylinder barrel port which, when cylinder barrel 4 is rotated, registers alternately with two approximately crescent shaped ports 55 and IS formed in valve seat 14 and communicating, re spectively, with two passages ii and I8 extending rearward therethrough. The arrangement is such that valve seat H coacts with the rear end of cylinder barrel l to form a valve for controlling the flow of liquid to and from cylinders It.

The outer ends of piston l l engage the annular inner surface of a thrust member 20 which is rotatably supported by a displacement varying member or slide block 2|. For the purpose of illustration, thrust member 20 has been shown a as being annular and as being supported within slide block 2| by a needle bearing 22. Axial movement of thrust member 29 is limited in any suitable manner as by means of a flange 23 formed on cylinder barrel 4 directly behind hearing 8 and by a ring H fitted upon hub I Slide block II is adapted to be shifted transversely of the axis of cylinder barrel 4 to vary the displacement of the pump but it is restrained 2,273,468 I by casing I from movement in any other direction. As shown in Fig. '3, slide block 2| is adapted to be moved toward the left by a cam 21 having its opposite ends connected to'two

pistons

28 and 29 which are fitted, respectively, in two

cylinders

30 and 3| fixed to casing I in alinement with each other.

Cam 21 has one of its faces inclined and in engagement with a contact 32 carried by slide block 2| and its opposite face arranged parallel to its path and in engagement with the flat inner end of a screw 33 which is threaded through the wall of casing I to prevent cam 21 from being deflected.

Slide block 2| is adapted to be shifted toward the right by a piston 34 fitted in a cylinder 35 which is carried ,by casing I and adapted to have motive liquid supplied thereto through a channel 36 from a source not shown, it being understood that pumps of this type ordinarily have a gear pump arranged in the casing thereof and driven in unison therewith. Slide block 2| may also be urged toward the right by a spring 31 which is arranged around cylinder 35 and holds contact 32 against cam 21 when servomotor 34-35 is deenergized.

The arrangement is such that, when cam 21 is in the position shown in Fig. 3, piston 34 and/or spring 31 will hold contact 32 in engagement with the center of cam 21 and thrust member 20 b will be concentric with cylinder barrel 4 so that rotation ofcylinder barrel 4 will not cause any reciprocation of pistons II and no liquid will be delivered by the pump.

When cylinders 36 and are supplied with liquid at the same pressure and cylinder 3I is opened to drain, piston 28 will move cam 21 upward and. cause it to shift slide block 2I toward the left and piston 34 will eject liquid from cylinder 35. Thrust member 20 will then be eccentric to cylinder barrel 4, and if cylinder barrel 4 is rotated in a clockwise direction as indicated by the arrow in Fig. 3, the pistons ID in the lower half of cylinder barrel 4 will move progressively outward and draw liquid into their cylinders through passages I 2 from port I6 and the pistons in the upper half of cylinder barrel 4 will be forced progressively inward and eject liquid from their cylinders through passages I2 into port I5.

When cylinders 3| and 35 are supplied with liquid and cylinder 30 is opened to drain, piston 29 will move cam 21 downward and then piston 34 will shift slide block 2I toward the right so that thrust member 20 is eccentric to cylinder barrel 4. Then rotation of cylinder barrel 4 in a clockwise direction will cause the pistons III in the upper half of cylinder barrel 4 to move progressively outward and draw liquid into their cylinders from port l5 and the pistons in the lower half of cylinder barrel 4 to be forced progressively inward and eject liquid from their cylinders into port I6 and thereby cause the pump to deliver liquid in a direction opposite to that in which it delivers liquid when slide block 4 is shifted toward the left from its neutral position.

If valve port I6 is connected to a'source of motive liquid and thrust member 20'is shifted toward the left from its central position, the motive liquid will force the pistons II in the lower half of cylinder barrel 4 outward against the annular inner surface of thrust member 20 and thereby cause cylinder barrel 4 to rotate in the direction of the arrow on Fig. 3 due to thrust member 20 being eccentric to cylinder barrel 4. Each piston II will be moved progressively outfrom ,its cylinder during ward by the liquid and impart rotary motion to cylinder barrel 4 during the half-revolution in which its cylinder is in communication with port I6 and then it will be moved progressively inward by thrust member 20 and exhaust liquid the half-revolution in which its cylinder is in communication with port I5. Therefore, when adjusted and supplied with motive liquid in this manner, the machine will function as a motor and cause shaft 9 to rotate in a clockwise direction in respect to Fig. 3. The direction of rotationof shaft 9 may be reversed either by shifting thrust member 20 toward the right from its central position or by directing the motive liquid into port I5 instead of into port I6. Regardless of whether the machine functions as a pump or as a motor, the liquid in one of the valve seat ports is under a high'pressure, the liquid in the other valve seat port is under a low, zero or negative pressure, minute quantities of liquid will escape from the high pressure port and spread over face I3 and the end of valveseat I4 to form a lubricating film therebetween, the pressure prevailing in the high pressure port will extend into the lubricating film, and the pressure prevailing in one or both the ports and in the film will tend to move the valve seat and the cylinder barrel away from each other.

Due to the pressure being very high in one valve seat port and very low or absent in the other valve seat port, the film pressure varies from a high pressure at the edge of the high pressure port to a low or zero pressure at the edge of the other port and to zero at the outer edge of the valve seat. Consequentlmthe center of pressure is not on the center of the valve seat but near the center of a high pressure area which extends around the high pressure port. In practice, this center of pressure is determined as closely as possible by calculation and then accurately established by experimentation,

" it being understood that the center of pressure is on one side of the cylinder barrel axis when one port is the high pressure port'and on the I other side of the cylinder barrel axis when the other port is the high pressure port. For example, the center of pressure in the machine shown is approximately at the center of the inner edge of the high pressure port. That is, when port I5 is the high pressure port, the center of pressure will be at or near the inner edge of that-port upon a line passing through the centers of both ports and the axis of the machine as indicated at 38 in Fig. 5 and, when port I6 is the high pres sure port, the center of pressure is on that line at or near the edge of port I6 as indicated at 39 in Fig. 5.

The machines heretofore provided with fiat valve seats are ordinarily of the axial type, the valve seats are fixed in stationary positions and the cylinder barrel is held against the valve seat either by the pistons or by a servo-motor arranged coaxial with the cylinder barrel.

When the cylinder barrel is held against the valve seat by the pistons, the design and size of the valve seat is limited and the force exerted by the pistons varies due to the fact that the, number of effective pistons varies in accordance with the number of cylinders in communication with the high pressure port at any given instant. For example, if the cylinder barrel contains seven cylinders, the number of cylinders in communication with the high pressure port will vary alternately between 3 and 4 so that the number of pistons urging the cylinder barrel against the valve seat will vary from 3 to 4.

When the cylinder barrel is held against the valve seat by a coaxial servo-motor, the force exerted thereby is centered on the axis of the cylinder barrel but the force tending to separate the valve seat and the cylinder barrel is centered at a point which is spaced 2. considerable distance from the cylinder barrel axis. Consequently, the cylinder barrel bears too heavily against the low pressure side of the valve seat and causes undue wear and it does not bear heavily enough against the high pressure side of the valve seat so that a considerable volume of, liquid leaks from between the cylinder barrel and the valve seat.

The present invention overcomes the above objectionable characteristics by restraining the cylinder barrel from axial movement and urging the valve seat against the cylinder barrel with a force which is proportional to the pressure of the motive liquid and centered at the center of the pressure tending to separate the cylinder barrel and the valve seat.

As shown, cylinder,.barrel 4 is restrained from axial movement by thrust bearing 6. The pressure acting upon the pressure area tends to move valve seat I4 rearward, and valve seat I4 is urged against face I3 by a force which is proportional to the pressure prevailing in the high pressure port and which is applied directly against the center of pressure 38 or 39 in order to prevent valve seat I4 from tending to tilt, thereby preventing undue wear of the abutting faces and keeping the leakage from between the cylinder barrel and the valve seat to a very low rate.

It has been found in practice that the leakage from between the cylinder barrel and the valve seat is only a small fraction of the corresponding leakage in any prior hydrodynamic machine of the same size and that the frictional drag on the cylinder barrel is considerably less than in the prior machines which are provided with pintles. Consequently, the machine has a much greater efficiency than could be obtained heretofore. Also, the film between cylinder barrel face and valve seat is not squeezed out during operation at extremely low speeds or even'when stalled. Hence the machine when functioning as a motor is capable of exerting its full torque at slow speeds and when stalled.

In a pump of sufficient size, valve seat I4 may be held against face I3 by a plurality of hold-up motors which are so arranged that the resultant of the forces exerted thereby lands directly upon the center of pressure as shown in Figs. 6 to 10.

In a reversible pump which is small enough to discharge its entire output through a single channel, the valve seat may be held against the cylinder barrel by one or the other of two holdup motors. If there is suflicient room, each of the motors may be arranged parallel to the cylinder barrel axis and in alinement with a pressure center 38 or 39 but, if the pump is very small, room may be obtained for each of these hold-up motors by arranging them at an angle to the cylinder barrel axis and so locating them that a component of the force exerted by each hold-up motor lands directly upon a pressure center 38 or 39. When the hold-up motor is arranged at an angle to. the cylinder barrel axis, the radial component of the force exerted by the motor may be utilized to cause the valve sponse to variations in pump pressure and theregrooves from being worn in of the valve seat and the by prevent annular the abutting faces cylinder barrel.

As shown, the rear part of valve seat I4 is rectangular and arranged loosely within a rectangular opening 40 (Fig. 4) formed in the rear wall H of easing I. Two

pins

42 and 42 are arranged in tw o recesses form'ed in opposite sides of the rectangular part of valve seat I4 upon opposite sides of, the horizontal center line thereof, and the outer ends of

pins

42 and 42" engage, respectively, two stacks of

flat leaf springs

43 and 43 which are arranged, respectively, in

suitable openings

44 and 44 formed in rear wall 4| upon opposite sides of opening 40, pins 42 and 42 preferably being so located that the axis of each pin passes through a pressure center 38 or 39 as shown in Fig. 5.

The arrangement is such that downward movement of valve seat I4 is prevented by the lower edge of opening 40 and lateral movement thereof is resisted by

springs

43 and 43 which will yield and permit it to move slightly toward the right or left in respect to Fig. 4 when it is subjected to a suflicient lateral force.

"The force for urging valve seat I4 against face I3- is supplied by one or the other f two hold-up motors the axes of which are inclined in opposite directions to the cylinder barrel axis and pass, respectively, through pressure centers 38 and 39.

As best shown in Fig. 2, one of the hold-up motors has its piston 45 fitted in a cylinder 46 which is adapted to be connected to one side of an external circuit as by means of a channel 4'I.

Piston 45 has a bore 48 formed therein and communicating with passage I! in valve seat I4 through a hollow connecting rod 49 which functions both as a connecting rod for transmitting force from piston 45 to valve seat I4 and as a channel for conveying liquid between passage I1 and cylinder 46.

The rear end of connecting rod 49 is substantially spherical and fitted into a complementary seat formed in piston 45 around bore 48 so as to form a fluid tight universal joint between piston 45 and rod 49. The front end of rod 49 is also substantially spherical and forms a fluid tight joint with a complementary seat which is formed in valve seat I4 around passage I1 and preferably has its center located at the intersection of a line passing transversely of the machine through pin 42 and 'a line passing longitudinally of the machine through pressure center 38.

The spherical ends of rod 49 are initially held in contact with their seats and valve seat I4 is initially urged against face I3 by a helical compression. spring 50 which is arranged in cylinder 46 and acts upon piston 45 to thereby maintain fluid tight joints at the ends of rod 49 and between valve seat I4 and face I3.

Since the second hold-up motor is exactly the same as motor 45-49, it has been shown only in dotted lines and the parts thereof have been indicated by the same reference numerals with the exponent a added thereto so that a complete description thereof is unnecessary.

The cylinder 46*- of the second hold-up motor communicates with a channel 41 by means of which it may be connected to the other side of an external circuit, and the connecting rod 49 thereof engages a spherical -seat which is g 2,273,403 1' 5 V formed in;.valve seat l4 around passage l5 and preferably has its center locatedatthe intersection-of a line passing transversely of the machine through pin 42- and a line passing longitudinally ofthe. machine through pressure center 55. a

The larrangement is such that the machine may discharge liquid through one hold-up motor into one side of an external circuit and be supplied with liquid through the other holdupmotor from the other sideflof the external circuit; and the pressure in each hold-up cylinder will be equal to .the pressure prevailing in the valve seat port with which that cylinder communicates.

The pressure in the cylinder 45 or 45* communicating with the high pressure port will cause the piston 45 or 45' therein to urge connecting rod 45 or 49 against valve seat l4 with v a force proportional to the pressure prevailing in the high pressure port. The axial component of this force will press valve seat l4 against face 15 and, since the axial component is applied to valve seat l4 in alinement with the pressure center, it will cause the entire end surface of valveseat l4 to bear evenly against face l5.

The radial component of this, force will act upon valve seat l4 along the'axis of

42 or 42 and will cause springs 45 or 43'- to' yield slightly and permit valve seat l4 to move radially and thereby cause each point on the end surface thereof to bear against a different point on-face l5. Valve seat l4 will thus move across face i3 in one direction or the other inresponse to a variation in pump pressure but the, maximum distance that it can move in either direction is very limited, for example, it is limited to about ten thousandths of an inch in a small pump. Y

Figs. 6 to 10 The 'pump in these figures has its mechanism arranged within a casing 5| which is provided with a separable'front head 52 and a separable rear head 53. Casing 5| has a cylinder barrel 54 rotatably supported therein by means of two bearings either or both of which may also resist axial movement of cylinder barrel 54. .As shown, the rear end of cylinder barrel 54 is supported by a ball bearing 55 and the front end thereof is supported by a thrust bearing 55.

Bearing55 is carried by casing 5| and fitted upon a hollow hub 51 which is formed upon the rear end of cylinder barrel 54. Bearing 55 is carried by front head 52 and fitted upon a hub 55 which is formed upon the front end of cylinder barrel 54 and has a shaft 55 fixed thereto and extending outward through front head 52 for connection with suitable source of power.

Cylinder barrel 54 has a plurality of radial cylinders 55 formed therein and a piston 5i fitted in each cylinder and extending beyond the periphery of cylinder barrel 54. The cylinders are ordinarily arranged in both circumferential and axial rows according to the usual practice and the number of rows or the number of cylinders in each row may bevaried to vary the displacement of the pump. In Fig. 6, each axial .row has been shown as consisting of two cylinders and each; circumferential rowmay containfive cylinders as shown inFig. 3.

The cylinders in each axial row communicute with a passage 52 formed in cylinder bara recess 55 which is formed in rear head 55.

In order that valve member 54 may be supported I within recess 55 and be free to adjust itself to face ,53 and thereby maintain a substantially fluid tight joint therebetween, its rear part is made somewhat smaller than recess 55 and provided with a small annular flange 55 whichis arranged near the center of gravity of valve member 54 and loosely fitted in recess 55, a notch 51 (Fig. 9) being formed in flange 55 to permit liquid to drain from the rear'end of recess 55.

Rotation of valve member 54 may be prevented in any suitable manner, such as by means of a pin fixed in end head 55 and loosely fitted in a hole formed in valve member 54, but it has been shown restrained from rotation by a key 55 fixed in end head 53 and loosely fitted in a suitable notch formed in flange 55, it being understood that'only a very slight movement of valve member 54 is necessary to enable it to adjust its front end to face 55 on cylinder barrel 54.

The rear end of each passage 52 constitutes a cylinder barrel port which, during rotation of cylinder barrel 54, registers alternately with two approximately crescent shaped

ports

59 and 59 formed in valve member 54 upon opposite sides of the cylinder barrel axis so that the valve member coacts with the rear end of the cylinder barrel to form a valve for controlling the flow of liquid drawn into and ejected from cylinders 55 by pistons.5l during rotation of cylinder barrel 54.

Each piston 5| is provided upon its outer end with an enlarged head having an arcuate contact face formed thereon. The contact faces on the heads of the pistons in each circumferential row are engaged by the conical inner surface of athrust ring 1| which engages each contact but rings 'Ilv have been shown as individual elements and retained in positionby suitable spacer rings in order to facilitate manufacture and selection of materials.

Thrust, member 12 is rotatably supported, as

by means of bearings 15 and '14, within a displacement varying member or slide block I5 which is shiftable transversely in a horizontal plane but is restrained by casing 5| from movement in any other direction. 'Slide block 15 may be shifted by any suitable means such, for example, as the displacement vafrying mechanism shown in Fig.3.

When slide block 15 is inits central or neutral position at which time it is concentric with cylinder barrel 54,-the'pump is'atzerostroke and no liquid will be delivered" thereby. When slide block 15 is shifted in one direction or the other, the pump will deliver liquid in a direction and at a rate dependent upon the direction and the distance slide block 76 is shifted from its neutral position.

When cylinder barrel 54 is rotated and slide block 15 is at one side of its central or neutral position, pistons 6| will move progressively outward during one half-revolution of cylinder barrotated in one direction and slide block 15 at one side oi its neutral position, the inward moving pistons will eject liquid from their cylinders through passage 62 into port 68 and the outward moving pistons will draw liquid into their cylinders through passage 62 from port- 68. If cylinder barrel 54 is rotated in the opposite direction or if slide blo'ck Ills shifted to the other side of its neutral position, pistons 6i will draw liquid from port 68 and discharge liquid into port 68'.

As previously explained, the pressure in oneport 68 or 68' is higher than the pressure in the other port regardless ofthe direction of liquid flow or whether the machine is functioning as a pump or as a motor, liquid escapes from the high pressure port and forms a lubricating film between valve member and face 63 on cylinder barrel 54, the forces exerted by the liquid in one or both of the ports and in the iilm tend to move cylinder barrel 54 and valve member 64 away from each other, andthe resultant of these 38 or 38 on Fig. 5.

Cylinder barrel 54 is restrained from axial movement by its bearings and, if the pump is of such size that an excessive thrust is imposed upon the cylinder barrel bearings due to the forces exerted upon the cylinder barrel by the liquid, the thrust on the bearings ls relieved by means to be presently descri Valve member64 is held against face 68 by a plurality of hold-up motors which are so arranged and proportioned that the resultant of the forces exerted thereby is coincident with and opposite to the resultant of the forces tending to move valve member 64 away from face 63. As

tively, to ports 68 and 68.

The center motor has its piston 16 in engageends of channel 88.

Channels

82 and 82 extend transversely of end head 53 and are adapted to be connected to opposite sides of an external circuit as by means of

pipes

83 and 88. The liquid in the channel .82 or 82 containing the higher pressure will move valve 8| against the opposite end of channel 88 and cause it to block communibeen indicated by like cation between cylinder 71 and the channel 82 or 82' containing the lower pre The arrangement is such that piston 16 is forced against valve member 64 by liquid supplied to cylinder H from the

channel

82 or 82" in which the pressure is the higher but the high pressure liquid is prevented by valve I8 from flowing into the

other channel

82 or 82".

Each of th pair 01 hold-up motors arranged above hold-up motor 16-11 has a hollow piston 85 fitted in a cylinder 86 which is formed in end head 53 and connected by a channel 81 to channel 82. The opening through piston 85 communicates through a hollow connecting rod 88 with a channel 89 which is formed in valve member 64 and communicates with port 69.

The ends of connecting rod 88 are spherical and engage complementary seats formed in valve member 64 and in piston 85 so as to form fluid tight joints between piston 85 and valve member 64 and to permit valve member 64 to adjust itcylinder barrel '64. The joints tight by a spring 98 which is arranged in cylinder 86 to urge piston 85 against connecting rod 88 and thereby urge valve member 64 against face 63 on cylinder barrel 54.

The pair of hold-up motors arranged below the center hold-up motor are exactly the same as hold-up

motors

85 and 86 and are connected to port 88 and channel 82* in exactly the same manner that motors 85-86 are connected to port 68 and channel 82. Consequently, like parts have reference numerals with the exponent a" added thereto and further description is deemed unnecessary.

The arrangement is such that channels 89, hollow connecting rods 88, hollow pistons 85, cylinders 86 and channels 8! and 82 are adapted to connect port 69 to one side of an external circuit and channels 86, hollow connecting rods 88*, hollow pistons 85, cylinders 86 and channels 81' and 82- are adapted to connect port 68 to the other side of an external circuit.

When the pump is performing usual work and pistons 6| are discharging liquid into port 68, the pump will create pressure which will act upon that the pressure can act upon piston 16, thereby causing

pistons

16 and 86 to urge valve member 64 against face 63 on cylinder barrel 64 with forces which are proportional to pump pressure.

If the pump is reversed so that pistons 6| are discharging liquid into port 88', the pump will create pressure which will act upon pistons 85, shift valve 8i and act upon piston 76 and thereby cause

pistons

16 and 85 to urge valve member 64 against face 68 on cylinder barrel 54 with forces which are proportional to pump pressure.

The hold-up motors are so proportioned and arranged that the resultant of the forces exerted by the three hold-up motors communicating with the high pressure port is coincident with and somewhat greater than the resultant of the forces the forces which barrel forward would impose an excessive thrust upon the cylinder barrel bearings, the pump is provided with hydraulic means for urging the cylinder barrel rearward with a force which is proportional to pump pressure and substantially equal to or slightly less than the force which tends to move the cylinder barrel forward.

Such hydraulic means may assume various forms but, for the purpose of illustration, front head 52 has been shown as having a cylinder 9I formed therein concentric with shaft 59 and supplied with liquid from the high pressure side of the pump through a channel 92 and other channels not shown.

Cylinder 9I has arranged therein an annular piston 93 which has as close a running fit with' the wall thereof as is commercially practical. The rear end of piston 93 is closely fitted to the end of hub 58 and initially held in contact therewith by a plurality of springs 94 each of which is arranged within piston 93 around a bolt 95 eflici-ency of the pump.

The'arrangement is such that cylinder barrel 54 is urged rearward by the liquid in cylinder 9I acting upon piston 93' which is so proportioned that the force exerted thereby i substantially equal to or' slightly less than the sum of the forces which tend to move cylinder barrel 54 forward. Since the forces which urge cylinder barrel 54 forward are substantially proportional to pump pressure and are opposed by a force which is nearly equal to the sum of those forces and is proportional to pump pressure, cylinder barrel 54 is in a nearly balanced condition at all times so that the only thrust imposed upon one or both of the cylinder barrel bearings is due to the small unbalanced forces.

, Fig. 11 The pump partially illustrated in this figure differs from the pump shown in Fig. 6 in that'the thrust ring II nearer the front of the pump has been reversed and moved forward from the position shown in Fig. 6. Since the two pumps may be otherwise identical, like parts have. been-indicated by like reference numerals and further description thereof is unnecessary.

When the pump is performing useful work, pisone half-revolution of cylinder barrel 54 and are forcedinward during the other half-revolution of cylinder barrel 54 by thrust rings H to therering may be resolved into a radial component which forces the piston inward and an axial component which tends to move the piston axially of the pump and thereby tends to move the cylinder'barrel axially.

If the thrust rings engage one half of the piscomponents of the pumping forces cancel each tons 6I are permitted to move outward during by cause them to pumpyliquid from one to the other so that no axial force is transmitted to the cylinder barrel. I

If the thrust rings engage all of the pistons upon that side of the piston axes toward the front of the pump as shown in Fig. 11, the axial components of the pumping forces will be transmitted to the cylinder barrel and tend to move it rearward, thereby relieving the cylinder barrel bearings of at least a part of the thrust imposed thereon by the forces which tend tomove the cylinder barrel forward.

It has previously been pointed. out that a small The mechanism shown in this figure differs from the mechanism shown in Fig. 10 in that the hollow connecting rods are omitted and the pistons of the upper and lower hold-up motors are free to tilt slightly in their cylinders. Since the mechanism is otherwise exactly-the same as the mechanism shownin Fig. 10, like parts and passages have been indicated by like reference numerals and no further description thereof is necessary. a

As shown, a valve member I64 is provided with diametrically

opposed ports

69 and 69 and arranged in a recess formed in an end head 53 which has a center hold-up motor 'I6--T|, upper and lower hold-up

motor cylinders

86 and 86 .and channels I9, 86, 82, 82*;61 and 81 arranged therein as previously explained, channel having a shuttle valve 8| arranged therein as shown in Fig. 6 but not shown in this figure.

Each hold-up cylinder 86 has arranged therein a hollow piston I85 which is somewhat smaller in diameter than cylinder 86 and provided with suitable piston rings for forming a fluid tight joint between piston I85 and the wall of cylinder 66. The opening through piston I85 communicates with a passage I89 which is formed in -valve member I64 and extends from the flat rear end thereof into communication with port 69.

The hold-up pistons could be formed integral with valve member I64 but a valve member with integral pistonswould be very difficult to manu facture. Therefore, they are ordinarily made separately and the front part of each piston I85 is reduced in diameter and provided with a flat end to engage the rear end of valve member I64 and form therewith a substantially fluid tight joint around passage I89. Contact between the front end of piston I85 and the rear end of valve member I64 is initially maintained-by a spring I96 which is arranged in cylinder 86 and urges piston I85 forward. The lower pair of hold-up motors are exactly the same as the upper pair and are connected to tons at one side of the axes thereof and en age the other half of the pistons at the other side of the axes thereof as shown in Fig. 6, the axial port 69 in the same manner that cylinders 86 are connected to port 69. Consequently, correspondmg parts and passages have been indicated by corresponding reference numerals with the exponent a added thereto and further description is unnecessary.

The hold-up mechanism functions in the same manner as the hold-up mechanism shown in Figs. 6 to .10 except that, when the hold-up mojoint between its front end and the face 63 on cylinder barrel 54, pistons I85 will tilt in cylinders 86 due tothe clearance between the periphcries of the pistons and the walls of the cylinders, it being understood that the movement of valve member )4 is very slight and only enough to compensate for wear and for irregularities in manufacture.

The invention described herein is susceptible of various other modifications without'departing from the scope of the appended claims in which the invention is defined as being applied to a pump but, since a hydrodynamic machine em bodying the invention will function either as a pump or as a motor, the term pump is used in the claims as being synonymous with the term motor and the claims are intended to cover a hydrodynamic machine regardless of whether it is used as a pump or as a motor.

The invention is hereby claimed as follows:

1. In a pump, the combination of a rotatable cylinder barrel restrained from axial movement and having a recess formed in the rear end thereof with its end wall substantially at right angles to the axis of said cylinder barrel, pumping means arranged in said cylinder barrel and communicating with said recess through the end wall thereof, a valve member arranged in said recess and forming with the end wall thereof a valve for controlling the fiow of liquid to and from said pumping means, a cylinder arranged in a stationary position for connection to an external circuit, a hollow piston fitted in said cylinder, a hollow connecting rod arranged upon said piston and engaging said valve member at said port for directing liquid from said valve member through said piston to said cylinder and for transmitting force from said piston to said valve member to thereby enable the liquid in said cylinder to cause said piston to urge said valve member against said end wall with a force proportional to pump pressure, and means independent of said connecting rod and said piston for preventing rotation of said valve member.

2. In a pump, the combination of a rotatable cylinder barrel restrained from axial movement and having pumping means arranged therein and passages extending from said pumping means through the rear endof said cylinder barrel, a valve member engaging the rear end of said cylinder barrel and forming therewith a valve for controlling the flow of liquid to and from said pumping'means, a stationary cylinder arranged at an angle to the axis of said cylinder barrel and adapted to be connected to an external circuit, a hollowpiston fitted in said cylinder, a hollow connecting rod arranged upon the axis of said cylinder and having its ends fitted into said piston and said valve member so that the liquid discharged by said pumping means is directed through said rod and said piston to said cylinder and exerts upon said piston a force proportional to pump pressure the axial component of which urges said valve member against i said cylinder barrel and the radial component bf which tends to move said valve member radially, I and yieldable means for supporting said valve member and for enabling said valve member to have a slight radial movement in response to a material-.yariation in pump pressure. 7

3. In a pump, the combination of a rotatable cylinder barrel restrained from axial movement and having 'a recess formed in the rear end 2,273,468 tors tilt valve member 64 to forma fluid tight angles to the axis of said cylinder barrel, pumping means arranged in said cylinder barrel and communicating with said recess through the end wall thereof, a valve member arranged in said recess and forming with the end wall thereof a valve for controlling the flow of liquid to and from said pumping means, a stationary cylinder arranged at an angle to the axis of said cylinder barrel and adapted to be connected to an external circuit, a hollow piston fitted in said cylinder, a hollow piston rod arranged upon the axis of said cylinder and having its ends fitted into said piston and said valve member so that the liquid discharged by said pumping means is directed through said rod and said piston to said cylinder and exerts upon said piston a force thereof with its end wall substantially at right 75 proportional to pump pressure the axial component of which urges said valve member againstsaid end wall and the radial component of which tends to move said valve member radially, and

yieldable means for supporting said valve member and for enabling said valve member to have a slight radial movement in response to a material variation in pump pressure.

4. In a pump, the combination of a rotatable cylinder barrel restrained from axial movement and having pumping means arranged therein and passages extending from said pumping means through the rear end of said cylinder barrel, a valve member engaging the rear end of said cylinder'barrel and forming therewith a valve for controlling the fiow of liquid to and from said pumping means, a stationary cylinder arranged at an angle to the axis of said cylinder barrel and adapted to be connected to an external circuit, a hollow piston fitted in said cylinder, a'

hollow piston rod arranged upon the axis of said cylinder and having its ends fitted into said piston and said valve member so that the liquid discharged by said pumping means is directed through said rod and said piston to said cylinder and exerts upon said piston a force proportional to pump pressure the axial component of which .urges said valve member against said cylinder barrel and the radial component of which tends to move said valve member radially,-and a plurality of leaf springs arranged upon opposite sides of said valve member for so supporting it that the radial component of said force will cause it to have a slight radial movement in response to a material variation in pump pressure.

5. In a pump, the combination of a rotatable cylinder barrel restrained from axial movement and having a recess formed in the rear end thereof with its end wall substantially at right angles to the axis of said cylinder barrel, pumping means arranged in said cylinder barrel and communicating with said recess through the end wall thereof, a valve member arranged in said recess and forming with the end wall thereof a valve for controlling the flow of liquid to and from said pumping means, a stationary cylinder arranged at an angle to the axis of said cylinder barrel and adapted ,to be connected to an extemal circuit, a hollow piston fitted in said cylto a material variation in it to have a slight radial pump pressure. 6. In a pump,'the combination of a rotatable cylinder barrel restrained from axial movement and having pumping means arranged therein and 7. In a pump, the combination of a rotatable cylinder barrel restrained from axial movement 8. In a pump, the combination of a rotatable cylinder barrel restrained from axial movement and having a recess formed in the rear end theretwo diametrically opposed arcuate cally directing liquid to said center cylinder from the other cylinder in which the pressure is the highest.

9. In a pump, the combination of a rotatable cylinder barrel restrained from axial movement and having a recess formed in the rear end there of with its end wall substantially at right angles to the axis of said cylinder barrel, pumping means arranged in said cylinder barrel and communisemblies for preventing rotation of said valve member.

WAL'I'ER FERRIS.