US2741993A

US2741993A - Pump or motor for high hydraulic pressures

Info

Publication number: US2741993A
Application number: US294661A
Authority: US
Inventors: Jr Elias Orshansky
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-06-20
Filing date: 1952-06-20
Publication date: 1956-04-17
Anticipated expiration: 1973-04-17

Description

E. ORSHANSKY, JR

April 17, 1956 PUMP OR MOTOR FOR HIGH HYDRAULIC PRESSURES Filed June 20, 1952 3 Sheets-Sheet 1 n .E :E:

April 17, 1956 E. ORSHANSKY, .JR

PUMP OR MOTOR FOR HIGH HYDRAULIC PRESSURES Filed June 20, 1952 3 Sheets-Sheet 2 nm. z m w n A w. H 0. 0 S m 'Wg /E l. 6 0 9 l. W

l/.IW\\\ :n

BY f

Trae/VE Y.

April 17, `1956 E. oRsHANsKY, JR 2,741,993

PUMP OR MOTOR FOR HIGH HYDRAULIC PRESSURES Filed June 20, 1952 3 Sheets-Sheet 3 United States Patent O PUMP on MOTOR Fon HIGH HYDRAULIC PREssUREs This invention relates to hydraulic apparatus capable of functioning either as a pump or as a hydraulic motor. More particularly, the invention relates to a mechanism of this character in which a plurality of cylinders and pistons is utilized, operating in cyclic sequence as the rotor of the mechanism moves angularly.

Such mechanisms, in which an eccentric is utilized for obtaining the reciprocating action, are, in general, well known. However, when high fluid pressures are attained or utilized, intolerable leakage of the uid is encountered, and a corresponding reduction in eliiciency results. When utilized as a pump, these leakage effects render attainment of high pressures much more difficult. One manner in which the leak losses may be reduced is by the aid of tight its between moving parts; but, in such an event, the power loss for either pump or motor operation makes it incapable of commercial exploitation.

Itis one of the objects of this invention to make it possible to operate a mechanism of this character without intolerable leakage, and at high pressures.

In order to accomplish this result, the fluid pressures existing in the mechanism are used to ensure the maintenance of close clearances between the relatively moving surfaces; and, furthermore, any unbalanced forces due to asymmetrical iluid pressures are ineffective to cause separation of such closely contacting relatively moving surfaces.

This invention possesses many other advantages, and has other objects whichmay be made more clearly apparent from a consideration of one embodiment of the invention. Forthis purpose, there is shown a form in the drawings accompanying and forming part of the present specification. The form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, sinceythe scope of this inventionis best defined by the appended claims.

Referring to the drawings:

Figure l is a vertical sectional view of an apparatus incorporating the invention;

Fig. 2 is a sectional view, taken along a plane corresponding to line 22 of Fig. l; f

Fig. 3 is a sectional view, taken along a plane corresponding to line 3 3 of Fig. 1;

Fig. 4 is a sectional view, taken along a plane corresponding to line 4-4 of Fig. l;

Fig. 5 is a sectional view, taken along a plane corresponding to line 5-5 of Fig. 1;

Fig. 6 is a pictorial view of the pressure balancing devices utilized in the construction shown in Fig. 1;

Fig. 7 is an exploded view of one of the pistons cooperating with the cylinder block utilized in the invention; and

Figs. 8 and 9 are fragmentary sectional views, taken along planes corresponding,` respectively; to lines 8-8 and 9--9 of Fig. 2. f

The operation of the structure, in this instance, is de- Nce scribed for hydraulic pumping, although, as heretofore stated, it may be used just as well as a hydraulic motor.

The operating parts of the pump are enclosed in a casing or housing formed of a casing member 1 (Figs. 1 and 2) and having a complementary casing member 2. A cover member 3 is also provided in which an inlet or intake port 4 and an outlet port 5 are formed.

The casing member 2 has a ange 6 telescoping within a corresponding opening in the casing member 1, and a sealing or O-ring 7 is disposed in an appropriate groove in the flange 6. The two casing members 1 and 2 are appropriately fastened together, as by the aid of bolts or studs. 4

Similarly, the cover 3 has a ilange 8 telescoped within a cylindrical opening in casing member 2. An O-ring 9 extends in a groove disposed around the ange 8, and serves to seal the casing. The cover member3 may be appropriately fastened to the casing member 2 to provide a closed and sealed casing structure.

' The moving parts of the pump structure include a cylinder block 10 rotatable about the main axis 11 of the apparatus. This axis extends transversely of casing structure 1-2-3.

The cylinder block 1l), in this instance, is shown as provided with radially extending equiangularly spaced cylinder spaces 12 (Figs. lV and 2), there being nine in the present instance. Each of the cylinder spaces 12 is provided atits inner end with a port 13 extending completely through the cylinder block 10. Each of these ports 13 acts alternately as an inlet port and as an Outlet port during the course of angular movement of the cylinder block 10 about axis 11. i Extending radially outwardly from the Outer periphery of the cylinder block 10 is an interrupted flange 14 integral with the block,(see, also, Fig. 8). The arcuate edges 15, adjacent portions of the ange 14, serve as additional guides for the reciprocating pistons 16 movable within the cylinder spaces 12.

The pistons are reciprocated by the rotation of the block 10.V This reciprocation is effected by the provision of a ring 17 mounted within the casing member 1 (Figs. l

and 2).` This ring 17 is pivoted upon a pin 1S for adjusti ing the eccentricity of its axis 19 with respect to the axis of rotation 11. `This pin 18 is appropriately fitted within the casing members 1 and 2.

Each of the pistons is provided with a contacting shoe 20 (see, particularly, Fig. 7). The outer surface of each of these shoes is in contact with the cylindrical interior surface 21 of ring 17. Ears 22 extend radially inwardly from each shoe 20 to be pivotally joined to the at end 23 of the corresponding piston 16. This pivotal connection is effected by the aid of a pin 24.

As the block 10 is rotated within the eccentric ring 17, the pistons 16 operate to provide a stroke corresponding to the eccentricity between the axes 11 and 19. In order to make this 1 stroke adjustable, an adjusting mechanism is providedjby the aid of which the angular position of the eccentric ring 17 may be adjusted about 'the axis of its pivot pin -18. l

For this purpose, a longitudinally adjustable bar 25 extends across the top of the `casing member 1. This bar 25 is provided with a transverse pivot pin 26 to opposite ends ofwhich are attached a pair of blocks. These blocks are accommodated within pairs of ears 2S formed on opposite sides of the ring 17 Accordingly, movement ofA the bar 25Y toward the right, as viewed in Fig. 2, would serve to reduce the eccentricity between the axes 11 vand 19.- Similarly, movement of the bar 25 toward the left would serve to increase the eccentricity.

Any appropriate-mechanism may be provided for the adjustment of the bar 25. v For example, the bar 25 may be provided with cylindrical ends 29 and 30 slidable in a housing 31, and adjusted by hydraulic pressure. This housing 31 is maintained in the casing 1 by the aid of the enlarged threaded end 32 threaded into an appropriate aperture in the right-hand wall of .casing 1. At its left-hand end the housing 31 is provided with an O-ring 33 accommodated in a groove formed in the `end ange of the housing. The left-hand end of the housing is spaced from the right-.hand end of a threaded member 34 for the accommodation of a sealing ring 35. This member 34 is threaded into the left-hand wall of the housing 1, and is provided with an O-ring 36 for eiecting an appropriate seal.

The cylindrical portion 29 is limited in its movement to the left by the right-hand surface of a stud 38. This stud 38 may be adjustably threaded into the threaded aperture in 4the member 34 for adjustment -of the extent of travel of the bar 25 toward the left. This stud may be kept in adjusted position by the aid of a lock nut 39. An appropriate leakage drain device 40 is disposed in the casing member 1 and communicates with the interior of the casing.

In order to rotate the block about its axis 11, it is clamped between a pair of rotatably mounted sleeve members. Thus, as viewed in Figs. l and 4, a sleeve member 41 is provided, and which has radial extensions 42. These radial extensions provide an interrupted cylindrical surface 43 which telescopes over the periphery of the block 10. The right-hand surfaces of these projections 42 contact the left-hand surface of interrupted flange 1'4. The

member 41 is generally cylindrical and provides a hub at its left-hand end to serve as a support for the inner race 44 of a ball bearing structure 45. The outer race 46 is accommodated within the cylindrical ange 47 formed in the casing member 2.

Similarly, a sleeve member 48 (Figs. l and 3) is provided with radial extensions 49 facing the extensions 42 and aligned therewith. This sleeve is provided with one or more apertures 74 (Fig. l) to permit any of the' uid that may leak from the pump to enter into the casing member 1. Radial extensions 49 provide an interrupted cylindrical surface 50 telescoping over the right-'hand portion of the cylinder block 10. The left-hand faces of the projections 49 contact the right-handv surface of the flange 14.

There are as

many projections

42 and 49 as there are cylindrical spaces 12, and they are located intermediate these cylinder spaces (Fig. 2). Through bolts 51 (see particularly Fig. 1) serve to hold the `

sleeve members

41 and 48 firmly in assembled relation with the 'block 10. These bolts pass through the aligned

projections

42 and 49.

The sleeve member 48 has a reduced cylindricalportion 52 upon which is mounted the inner race 53 of the ball bearing structure 54. The outer race 55 is accommodated within the hollow extension 56 of the casing member 1. Extending to the Vright of the portion 52 is an integrally attached hollow splined member 57 adapted to accommodate the splined end on a shaft 'for the rotation of the cylinder block 10.

In order to close the casing structure, a cover plate 58 is provided surrounding the member 57 and'held in place as by a split spring 59. This plate 58 contacts the right hand surface of the ring 60, in which outer race 55 Vis accommodated. A conventional sealing ring 64 is carried by the plate 58 for cooperation with the exterior periphery of the splined member 57. The ring 60 of the ball bean ing structure has a left-hand surfacecontacting lthe shoulder 61 in the casing member 1. Accordingly, the 'spring ring 59 serves to maintain the bearing structure Aand the sleeve member 48 in appropriate axial kposition with rcspect to the casing 1.

- In yorder to ensure that the -shoes will be maintained against the interior surface 21 ofthe ring 17 `without angular displacement'about pin 24, use is lmade of a .pair of guide rings 62 and 63. These are disposed on each side of the ange 14, and are in contact with the interior surface of the shoe 20. Furthermore, each of the shoes 20 is provided with the side anges 65 for maintaining these rings 62 and 63 against axial movement and for conning the rings against the ears 22. These rings are wide enough (Fig. l) to overlap the ends of the pins 24, thereby maintaining these pins against removal.

The cover member 3 is provided with an inwardly projecting cylindrical member 66 (Figs. l and 4) that provides a smooth plane surface 67 to which the left-hand surface of cylinder block 10 is opposed. Extending into this face is an arcuate outlet port 68 in communication with the port 5, as by the aid of a drilled aperture 110. A similar port 69, below the axis 11, is provided communicating with the inlet port 4 (see particularly Fig. 4).

These

ports

68 and 69 are kidney-shaped, and each of them extends for an angle somewhat less than 180 around the .axis i1. They are adapted to communicate in succession with groups of cylinder ports 13 as the cylinder block 10 is rotated.

Thus, in the position of Fig. 2, those ports 13 above the horizontal line 70 are in communication with the outlet port 68; and those ports 13 which are below the horizontal line 70 Lare in communication with the inlet port 69. As viewed in Fig. 2, therefore, as the block 10 rotates in a clockwise direction, the pistons 16 above line 70, operating in the cylinders 12, are urged inwardly to a maximum inward position, illustrated at the righthand side of the block 10. Similarly, the pistons 16 in the lower portion of the block 10 gradually move outwardly for receiving a charge of liquid through the inlet port'69.

ln order to maintain a definite clearance for the block 10, a spacer sleeve 7l is provided. This spacer sleeve extends through the block 10, and is doweled to the cy1indrical projection 66 `of cover member 3. A stationary wall-forming member 72 (Fig. 6) that has a left-hand face 73 opposed .to the block 10 serves to conne this block against substantial axial movement. This face is held in spaced-apart relation with respect to the wall 67 by the aid of the spacer sleeve 71. This member 72 may be doweled to the spacer sleeve 71, as indicated in Fig. l. It is formed integrally with a cylindrical extension 101 which is made eccentric with respect to member 72 (Fig. 6).

The spacer 71 is made very slightly greater in length than the axial depth of the block 10. Accordingly, the clearance between the block 10 and surfaces 67 and 73 may be of the order of one-half of one-thousandth of an inch. In a typical construction, before there is any strain due to pressures, the clearance between lthe block 10 and these walls 67 and 73 is .0004 inch.

Without exceptional precautions, the outlet pressures, which may be of the order of several thousand pounds per square inch, would exert forces tending to urge the walls 67 and 73 apart. These forces are exelted via the cylinder ports 13 located over the horizontal line '70 (Fig. l). The resultant or combination of all these forces has a center ofgravity substantially above the line 70. Accordingly, this resultant force tends to distort or cock the spacer '71, with consequent resultant misalignmcnt of the parts and increased leakage.

In order substantially to balance the pressure affecting the spacer 71, a pressure space is kformed between the member 72 and-a supplemental pressure balancing mem- 'Der 75 (Figs. l and 6). For this purpose, this member 75 has a surface 76 (Fig. 6) opposed to the rear surface 77 of the :member 72. The surfaces 7-6 and 77 are crescent-shaped due tothe eccentricity of the outer periphery of the member 101 with respect to the axis 11. Sealing O-

rings

78 and 79 extend in grooves in the members 72 and 1'01, and serve Vto Asealrespectively against the flange 80 of member75 and the cylindrical surface 81 cooperating with the right-hand portion 101 of member 72. As indicated most clearly in Fig. l, the space formed annees between

members

72 and 75 is quite confined, and is in constant communication with the outlet port 68, via` the cylinder ports 13 above line 70, and port 82` (see, also, Figs. 3 and 6). This port extends through the member 72 from a shallow recess 83 extending substantially 180 around the axis 11, and located in the left-hand face of member 72. Accordingly, the port 82 in this manner is in communication with substantially all of the cylinder ports 13 that extend above thehorizontal line 70; and the space between

members

72 and 75 is subjected to a hydraulic pressure corresponding to the high pressure side of the mechanism. The pressure acting on opposite sides of member 72 is thereby substantially balanced.

The exertion of pressure upon the surface 76 of member 75 tends to cock this member about the axis 11. In order to ensure that this cocking can be effected without in any way interfering with the proper alignment of the Walls 67 and 73, there is clearance between the flange 80 and the outer periphery of member 72, as well as between the cylindrical surface 81 of member '75 and the extension 101 of member 72.

The spacer 71, however, is quite rigidly held in place by the aid of a supplemental sleeve member 84. This sleeve member extends through the spacer 71, and is held in place by the collar 85 formed integrally with a central post 86. This collar 85 engages the inwardly directed flange 90, carried by the left-hand end of the sleeve 84. This ange urges the sleeve 84 toward the right-hand surface 67 of the boss 66. For this purpose, the left-hand end 87 of the post 86 is threaded to engage in an appropriate threaded aperture in the boss 66.

The right-hand end of the sleeve 84 is provided with a ange 88. The left-hand surface of this flange 88 contacts the narrow annular boss 89 (Fig. 6) extending around the through bore of the member 72. The ange 88 urges the spacer 71 and member 72 tightly against the surface 67 The flange 90 has a slight lclearance with respect to this surface to permit a force to be exerted `by flange 88 upon the right-hand side of member 72.

The post 86 carries a collar or flange 91 against which the right-hand surface of member 75 abuts. AAn enlarged portion 92 of the post 86 extends toward the right of this `flange 91, and is mounted by the aid of a ball bearing structure 93 within the member 48.

The extension 92 serves as a rigid end support for the post 86 to resist iexure thereof. However, flexure of the member 75 is permitted, since clearances are provided between the member 75 and the cooperating surfaces of member 72 and sleeve 84.

The compensating pressure areas are indicated in general in Fig. 5. The area on the left-hand surface of member 72, as viewed in Fig. 1, which is subjected to outlet -pressure, may be represented in Fig. by the semicircular annulus above line 70, and between the circles 94and 95. The circle 94 corresponds `to the outer periphery of member 72, and the circle 95 corresponds to the outer periphery of the spacer 71.

An opposing pressure on the right-hand surface of ,member 72, as viewed in Fig. l, is that corresponding to the crescent-shaped area between the circle 94 and the circle 96. The latter circle 96 corresponds to the periphery of the extension 101. The centers of gravity of these areas are substantially coincident. Furthermore, the areas lare substantially the same. Accordingly, there is substantially complete balance of pressures on opposite sides of the member '72. A balancing of stresses acting upon the spacer 71 is thus substantially accurately effected.

The inventor claims: f l. In a hydraulic mechanism: a block; a member having relative movement with respect to the block for utilization or creation of hydraulic pressure; means for providing said movement; means forming walls on opposite sides of the block; a spacer between said walls for `maintaining a running clearance for the block; one of said lwalls having inlet and outlet passages; and means forming,

with one of the walls, a space on that side of the said wall opposite to the side that faces the block, and in communication with one of the passages, the surface of said side that forms said space presenting an area of pressure for substantially balancing thev pressure on the other side of said one of the walls.

2. In a hydraulic mechanism: a block; a member having relative movement with respect to the block for utilization or creation of hydraulic pressure; means for providing said movement; means forming walls on opposite sides of the block; a spacer between said walls for maintaining a running clearance for the block; one of said walls having inlet and outlet passages; means forming, with one of the walls, a space on that side of the said wall opposite to the side that faces the block, and in communication with one of the passages, the surface of said side that forms said space presenting an area of pressure for substantially balancing the pressure on the other side of said one of the walls; and means for so mounting said spaceforming means as to permit deection thereof independently of the cooperating wall forming means.

3. In a hydraulic mechanism: a block; a member having relative movement with respect to the block for utilization or creation of hydraulic pressure; means for providing said movement; means forming walls on opposite sides of the block; a spacer between said walls for maintaining a running clearance for the block; one of said Walls having inlet and outlet passages; means forming, with the other of the walls, a space on that side of the said wall opposite to the side that faces the block, and in communication with one of the passages, the surface of said side that forms said space presenting an area of pressure for substantially balancing the pressure on the other side of said other wall; means for so mountingsaid space forming means as to permit deflection thereof independently of the cooperating wall forming means; an abutment for the space forming means; and means fastening said abutment to only the said one of the walls.

4. In a device of the character described: means forming a pair of spaced walls; a cylinder block between the walls; one or more pistons cooperating with cylinder spaces in the block; a spacer between the walls for main` taining a running clearance for the block; said block having cylinder ports; means providing relative angular movement between the walls and the block about an axis for producing reciprocation of the pistons; one of said walls having a high pressure passage for fluid communicating with some of the cylinder ports; and means forming, with the other wall, a pressure space on that side of the said other wall opposite to the side that faces the block, and in communication with said passage, the surface of said side that forms said space presenting an area of pressure for substantially balancing the pressure on the opposite sides of said other wall. l

5. In a device of the character described: means forming a pair of spacedk parallel walls; a cylinder block between the walls; one or more pistons cooperating with cylinder spaces in the block; a spacer between the walls for maintaining a running clearance for the block; said` block having cylinder ports; means providing relative angular movement between the walls and the block about an axis for producing `reciprocation of the pistons; one of said Walls having a high pressure passage for fluid communicating with some of the cylinder ports; and

ymeans forming, with the other wall, a pressure space on that side of the said other wall opposite to the side that faces the block, and in communication with said passage, the surface of said side that forms said space presenting an area of pressure substantially equal to the area exposed on the other side of the other wall, to the high pressure.

6. In a device of the character described: means forming a pair of spaced parallel walls; a cylinder blockl between the Walls; one or more pistons cooperating with cylinder spaces in the block; a spacer between the walls for maintaining a running' clearance for the block; said block having cylinder ports; means providing relative angular movement between the walls and the block about an axis for lproducing reciprocation of the pistons; one of said walls having a high pressure passage for fluid communicating with some of the cylinder ports; means utilizing the iiuid pressure existing in said passage for substantially balancing the uid pressure on opposite sides of the other wall; and means so mounting said space forming means as to permit deflection thereof, independently :of the wall forming means.

7. In a device of the character described: means forming a pair of spaced parallel walls; a cylinder block between the walls; one vor more pistons cooperating with cylinder spaces in the block; a spacer between the walls for maintaining a running clearance for the block; said block having cylinder ports; means providing relative angular 'movement between the walls and the block about an axis for producing reciprocation of the pistons; one of said walls having a high pressure passage for fluid communicating with some of the cylinder ports; means utilizing the uid pressure existing in 'said passage for substantially balancing the fluid pressure on opposite sides of the other wall; means so mounting said space forming means as to permit deilection thereof, independently of the wall forming means; an abutment for the space forming means; and means fastening said abutment only to the one of said walls.

8. In a device of the character described: means forming a pair of spaced parallel walls; a spacer between the walls; a rotary cylinder block having an axis of rotation passing through the spacer and provided with a plurality of cylinders; said block having running clearance between the walls; each of said cylinders having a port; pistons in the cylinders; means for causing the pistons to reciprocate as the block is rotated; one of the walls .having ,a high fluid pressure passage communicating cyclically with a portion of all of the cylinder ports as the block is' rotated; and means forming with the other of said walls, a space on that side said other wall, opposite to the side that faces the spacer, and in communication with said passage via said ports, the surface .of said side that forms said space presenting an arca of pressure for substantially balancing the pressure on the opposite sides of said other wall.

9. In a device of the character described: means forming a pair of spaced parallel walls; a spacer between the walls; a rotary cylinder block having an axis of rotation passing through the spacer and provided with a plurality of cylinders; said block having running clearance between the walls; each of said cylinders having a port; pistons in the cylinders; means for causing the pistons to reciprocate as the block is rotated; one of the walls having a high fluid pressure passage communicating cyclically with a portion of all of the cylinder ports as the block is rotated; means forming with the other of said walls, a space on that side of said other wall, opposite to the side that faces the spacer, and in communication with said passage via said ports, the surface of said side that forms said space presenting an area of pressure for substantially balancing the pressure on the spacer; and means for mounting said space forming means in a manner to permit deflection thereof independently of the cooperating wall forming means.

l0. In a device of the character described: means forming a pair of spaced parallel walls; a spacer between the walls; a rotary cylinder block having an axis of rotation passing through the spacer and provided with a plurality of cylinders; said block having running clearance between the walls; each of said cylinders having a port; pistons in the cylinders; means for causing the pistons to reciprocate as the block is rotated; one of the walls having a high fluid pressure passage communicating cyclically with a portion of all of the cylinder ports as the block is rotated; means forming with the other of said walls, a

space on that side of said other wall, opposite to the side that faces the spacer, and in communication with said passage via said ports, the surface of said side that forms said space presenting an area of pressure for substantially balancing the pressure on the spacer; means for mounting said space forming .means in a manner to permit deection thereof independently of the cooperating wall forming means; an abutment for the other side of said other walls; and means passing through the spacer for fastening said abutment to the said one of the Walls.

ll. In a device of the character described: means forming a pair of spaced parallel Walls; a spacer between the walls; a rotary cylinder block having an axis of rotation passing through the spacer and provided with a plurality of cylinders extending radially of the axis; said block having running clearance between the walls; each of said cylinders having a port; pistons in the cylinders; means for causing the pistons to reciprocate as the block is rotated; one of the walls having high iluid pressure passage communicating cyclically with substantially half of the cylinder ports as the block is rotated; means forming another passage communicating with the remainder of the ports; and means forming, with the other of said walls, a pressure space with the other wall and in communication with the high pressure passage via the cylinder ports, the surface of said other wall that defines said space presenting an area balancing the pressure on the spacer.

l2. In a device of the character described: means forming a pair of spaced parallel walls; a spacer between the walls; a rotary cylinder block having an axis of rotation lpassing through the spacer and provided with a plurality of cylinders extending radially of the axis; said block having running clearance between the walls; each of said cylinders having a port; pistons in the cylinders; means for causing the pistons to reciprocate as the block is rotated; one of the walls having high fluid pressure passage communicating cyclically with substantially half of the cylinder ports as the block is rotated; means forming another passage communicating with the remainder of the ports; means forming, with the other of said walls, a pressure space with the other wall and in communication with the high pressure passage via the cylinder ports, the surface of said other wall that defines said space presenting an area balancing the pressure on the spacer; and means for mounting said space forming means in a manner to permit deflection thereof independently of the cooperating wall forming means.

13. l'n a device of the character described: means forming a pair of spaced parallel walls; a spacer between the walls; a rotary cylinder block having an axis of rotation passing through the spacer and provided with a plurality of cylinders extending radially of the axis; said block having running clearance between the walls; each of said cylinders having a port; pistons in the cylinders; means for causing the pistons to reciprocate as the block is rotated; one of the walls having high uid pressure passage communicating cyclically with substantially half of the cylinder ports as the block is rotated; means forming another passage communicating with the remainder of the ports; means forming, with the other of said walls, a pressure space with the other wall and in communication with the high pressure passage via the cylinder ports, the surface of said other wall that deiines said space presenting an area balancing the pressure on the spacer; means for mounting said space forming means in a manner to permit deflection thereof independently of the cooperating wall forming means; an abutment for that side ofthe other wall which defines said space; and means passing thro-ugh the spacer for fastening said abutment to the said one of the Walls.

14. in a device of the character described: a rotary cylinder block member having an axis of rotation, and provided with a plurality of cylinder bores opening in 9 the outer periphery of the block member; each of said bores having a port that opens on a side surface of the block member; pistons in the cylinders; means for causing the pistons to reciprocate as the block member is rotated; a non-rotary wall member having a surface adjacent one side surface of the block member, said adjacent surfaces being subjected to outlet pressure; a spacer structure associated with one of the members so as to provide a running clearance in an axial direction for the said one of the members; a casing for the members and providing inlet and outlet openings adapted to communicate in succession with a group of cylinder ports;

10 and means utilizing outlet pressure for balancing the force due to pressure existing on one of the said adjacent surfaces of one of the members.

References Cited inthe le of this patent UNITED STATES PATENTS 2,273,468