Hydrostatic radial piston machine

Abstract

A hydrostatic radial piston machine includes a radial cylinder block with cylinder bores which extend from an outer circumferential surface of the radial cylinder block into an interior of the radial cylinder block; a number of pistons which corresponds to the number of cylinder bores; a cam ring, and ends of the pistons which face away from the radial cylinder piston block are supported movably on an inner circumferential surface of the radial cylinder block during a rotation of the radial cylinder block; two control plate elements which extend respectively with a face oriented towards the radial cylinder block towards a central plane of the radial cylinder block, which central plane is perpendicular to the rotation axis. Each control plate element includes a bearing portion in which radially acting forces are transferable to a respective mating surface in the housing or housing cover mounted in the housing.

Claims

1. A hydrostatic radial piston machine, comprising: a housing; a radial cylinder block rotatably supported in the housing about a rotation axis and including a plurality of bores extending from an outer enveloping surface of the radial cylinder block into an interior of the radial cylinder block and arranged distributed over a circumference of the radial cylinder block; a plurality of pistons which corresponds to the plurality of bores, wherein the pistons are movably supported in the bores and respectively define an operating cavity for a hydraulic fluid together with the associated bore; a cam ring which is arranged eccentric relative to the radial cylinder block and which circumferentially envelops the radial cylinder block and wherein ends of the pistons oriented away from the radial cylinder block are movably supported at a continuously cambered inner enveloping surface of the cam ring during a rotation of the radial cylinder block; two control plate elements including a total of at least two control cross-sections, at least one control cross-section connected with an inlet channel and at least another control cross-section connected with an outlet channel, wherein the two control plate elements extend respectively with a face oriented towards a central plane of the radial cylinder block, wherein the central plane is perpendicular to the rotation axis, and the two control plate elements extend with the faces oriented towards the radial cylinder block beyond a plane which is defined by a face of the radial cylinder block, wherein the face of the radial cylinder block is oriented towards the respective control plate element at a greatest axial width of the radial cylinder block; a plurality of pass through channels in the radial cylinder block corresponding to the plurality of bores in the radial cylinder block, wherein the pass through channels as a function of a rotational position of the cylinder block in the cam ring respectively connect the operating cavity with the control cross-section corresponding with the inlet channel or with the control cross-section corresponding with the outlet channel or are closable by a closing surface arranged at the control plate element, wherein each control plate element includes a radial bearing portion in which radial forces from the radial cylinder block are transferrable to a respective opposite radial surface in the housing or to a radial surface of a housing cover supported in the housing through a direct contact of the radial bearing portion with the radial surface.

2. The radial piston machine according to claim 1, wherein the at least one control plate element penetrates the radial cylinder block in an axial direction so that the radial cylinder block and the at least one control plate element engage one another.

3. The radial piston machine according to claim 1, wherein the pass through channels of the radial cylinder block which interact respectively with the operating cavity extend respectively from a support portion to an opposite support portion of the cylinder block.

4. The radial piston machine according to claim 1, wherein the control plate element has a conical, cone ring shaped or convex spherically cambered shape, wherein a support portion of the control plate element is configured conical, conical ring shaped or convex-spherically cambered shaped.

5. The radial piston machine according to claim 1, wherein control channels of the two opposite control plate elements and one of the pass through channels of the radial cylinder block arranged there between are aligned with one another, forming a continuous cylindrical bore with a constant cross-section.

6. The radial piston machine according to claim 1, wherein the continuously cambered inner enveloping surface of the cam ring is continuously spherically cambered.

7. A hydrostatic radial piston machine, comprising: a housing; a radial cylinder block rotatably supported in the housing about a rotation axis and including a plurality of bores extending from an outer enveloping surface of the radial cylinder block into an interior of the radial cylinder block and arranged distributed over a circumference of the radial cylinder block; a plurality of pistons which corresponds to the plurality of bores, wherein the pistons are movably supported in the bores and respectively define an operating cavity for a hydraulic fluid together with the associated bore; a cam ring which is arranged eccentric relative to the radial cylinder block and which circumferentially envelops the radial cylinder block and wherein ends of the pistons oriented away from the radial cylinder block are movably supported at an inner enveloping surface of the cam ring during a rotation of the radial cylinder block; two control plate elements including a total of at least two control cross-sections, at least one control cross-section connected with an inlet channel and at least another control cross-section connected with an outlet channel, wherein the two control plate elements extend respectively with a face oriented towards a central plane of the radial cylinder block, wherein the central plane is perpendicular to the rotation axis, and both control plate elements extend with the faces oriented towards the radial cylinder block beyond a plane which is defined by a face of the radial cylinder block, wherein the face of the radial cylinder block is oriented towards the respective control plate element at a greatest axial width of the radial cylinder block; a plurality of pass through channels in the radial cylinder block corresponding to the plurality of bores in the radial cylinder block, wherein the pass through channels as a function of a rotational position of the cylinder block in the cam ring respectively connect the operating cavity with the control cross-section corresponding with the inlet channel or with the control cross-section corresponding with the outlet channel or are closable by a closing surface arranged at the control plate element, wherein each control plate element includes a radial bearing portion in which radial forces from the radial cylinder block are transferrable to a respective opposite radial surface in the housing or to a radial surface of a housing cover supported in the housing through a direct contact of the radial bearing portion with the radial surface, wherein the radial cylinder block includes at least one support portion in which an axial width is smaller than in a freewheeling portion adjacent to the at least one support portion of the radial cylinder block in radially outward direction, wherein the at least one control cross-section of the control plate element is arranged in the at least one support portion of the radial cylinder block, wherein the at least one control plate element includes a control plate element support portion corresponding with the at least one support portion of the radial cylinder block, wherein the respective radial bearing portion either adjoins the control plate element support portion in a radially outward direction or is oriented away from the control plate element support portion in an axial direction.

8. The radial piston machine according to claim 7, wherein the at least one support portion of the radial cylinder block extends from a central torque coupling portion in radial direction to a diameter which has a size of 60% to 90% of a maximum diameter of the radial cylinder block.

9. The radial piston machine according to claim 7, wherein the at least one support portion of the radial cylinder block extends from a central torque coupling portion in radial direction to a diameter which has a size of 70% to 80% of a maximum diameter of the radial cylinder block.

10. A hydrostatic radial piston machine, comprising: a housing; a radial cylinder block rotatably supported in the housing about a rotation axis and including a plurality of bores extending from an outer enveloping surface of the radial cylinder block into an interior of the radial cylinder block and arranged distributed over a circumference of the radial cylinder block; a plurality of pistons which corresponds to the plurality of bores, wherein the pistons are movably supported in the bores and respectively define an operating cavity for a hydraulic fluid together with the associated bore; a cam ring which is arranged eccentric relative to the radial cylinder block and which circumferentially envelops the radial cylinder block and wherein ends of the pistons oriented away from the radial cylinder block are movably supported at an inner enveloping surface of the cam ring during a rotation of the radial cylinder block; two control plate elements including a total of at least two control cross-sections, at least one control cross-section connected with an inlet channel and at least another control cross-section connected with an outlet channel, wherein the two control plate elements extend respectively with a face oriented towards a central plane of the radial cylinder block, wherein the central plane is perpendicular to the rotation axis, and the two control plate elements extend with the faces oriented towards the radial cylinder block beyond a plane which is defined by a face of the radial cylinder block, wherein the face of the radial cylinder block is oriented towards the respective control plate element at a greatest axial width of the radial cylinder block; a plurality of pass through channels in the radial cylinder block corresponding to the plurality of bores in the radial cylinder block, wherein the pass through channels as a function of a rotational position of the cylinder block in the cam ring respectively connect the operating cavity with the control cross-section corresponding with the inlet channel or with the control cross-section corresponding with the outlet channel or are closable by a closing, surface arranged at the control plate element, wherein each control plate element includes a radial bearing portion in which radial forces from the radial cylinder block are transferrable to a respective opposite radial surface in the housing or to a radial surface of a housing cover supported in the housing through a direct contact of the radial bearing portion with the radial surface, wherein the control plate element has a conical, cone ring shaped or convex spherically cambered shape, wherein a support portion of the control plate element is configured conical, conical ring shaped or convex-spherically cambered shaped, and wherein a cone angle of the control plate element is between 90° and 150°.

11. A hydrostatic radial piston machine, comprising: a housing; a radial cylinder block rotatably supported in the housing about a rotation axis and including a plurality of bores extending from an outer enveloping surface of the radial cylinder block into an interior of the radial cylinder block and arranged distributed over a circumference of the radial cylinder block; a plurality of pistons which corresponds to the plurality of bores, wherein the pistons are movably supported in the bores and respectively define an operating cavity for a hydraulic fluid together with the associated bore; a cam ring which is arranged eccentric relative to the radial cylinder block and which circumferentially envelops the radial cylinder block and wherein ends of the pistons oriented away from the radial cylinder block are movably supported at an inner enveloping surface of the cam ring during a rotation of the radial cylinder block; two control plate elements including a total of at least two control cross-sections, at least one control cross-section connected with an inlet channel and at least another control cross-section connected with an outlet channel, wherein the two control plate elements extend respectively with a face oriented towards a central plane of the radial cylinder block, wherein the central plane is perpendicular to the rotation axis, and both control plate elements extend with the faces oriented towards the radial cylinder block beyond a plane which is defined by a face of the radial cylinder block, wherein the face of the radial cylinder block is oriented towards the respective control plate element at a greatest axial width of the radial cylinder block; a plurality of pass through channels in the radial cylinder block corresponding to the plurality of bores in the radial cylinder block, wherein the pass through channels as a function of a rotational position of the cylinder block in the cam ring respectively connect the operating cavity with the control cross-section corresponding with the inlet channel or with the control cross-section corresponding with the outlet channel or are closable by a closing surface arranged at the control plate element, wherein each control plate element includes a bearing portion in which radial forces from the radial cylinder block are transferrable to a respective opposite surface in the housing or to a housing cover supported in the housing, wherein both control plate elements are movable in axial direction relative to one another, wherein one of the control plate elements is movable in an axial direction relative to the housing or the housing cover, and wherein the other control plate element is fixated in the axial direction in the housing or the housing cover.

12. A hydrostatic radial piston machine comprising: a housing; a radial cylinder block rotatably supported in the housing about a rotation axis and including a plurality of bores extending from an outer enveloping surface of the radial cylinder block into an interior of the radial cylinder block and arranged distributed over a circumference of the radial cylinder block; a plurality of pistons which corresponds to the plurality of bores, wherein the pistons are movably supported in the bores and respectively define an operating cavity for a hydraulic fluid together with the associated bore; a cam ring which is arranged eccentric relative to the radial cylinder block and which circumferentially envelops the radial cylinder block and wherein ends of the pistons oriented away from the radial cylinder block are movably supported at an inner enveloping surface of the cam ring during a rotation of the radial cylinder block; two control plate elements including a total of at least two control cross-sections, at least one control cross-section connected with an inlet channel and at least another control cross-section connected with an outlet channel, wherein the two control plate elements extend respectively with a face oriented towards a central plane of the radial cylinder block, wherein the central plane is perpendicular to the rotation axis, and the two control plate elements extend with the faces oriented towards the radial cylinder block beyond a plane which is defined by a face of the radial cylinder block, wherein the face of the radial cylinder block is oriented towards the respective control plate element at a greatest axial width of the radial cylinder block; a plurality of pass through channels in the radial cylinder block corresponding to the plurality of bores in the radial cylinder block, wherein the pass through channels as a function of a rotational position of the cylinder block in the cam ring respectively connect the operating cavity with the control cross-section corresponding with the inlet channel or with the control cross-section corresponding with the outlet channel or are closable by a closing surface arranged at the control plate element, wherein each control plate element includes a radial bearing portion in which radial forces from the radial cylinder block are transferrable to a respective opposite radial surface in the housing or to a radial surface of a housing cover supported in the housing through a direct contact of the radial bearing portion with the radial surface, wherein one control plate element of the two control plate elements is arranged respectively on both sides of the radial cylinder block, and wherein a first control plate element of the two control plate elements is preloaded through a spring element supported at the housing or at the housing cover in a direction towards a second opposite control plate element of the two control plate elements.

13. A hydrostatic radial piston machine, comprising: a housing; a radial cylinder block rotatably supported in the housing about a rotation axis and including a plurality of bores extending from an outer enveloping surface of the radial cylinder block into an interior of the radial cylinder block and arranged distributed over a circumference of the radial cylinder block; a plurality of pistons which corresponds to the plurality of bores, wherein the pistons are movalaly supported in the bores and ressectively define an operating cavity for a hydraulic fluid together with the associated bore; a cam ring which is arranged eccentric relative to the radial cylinder block and which circumferentially envelops the radial cylinder block and wherein ends of the pistons oriented away from the radial cylinder block are movably supported at an inner enveloping surface of the cam ring during a rotation of the radial cylinder block; two control plate elements including a total of at least two control cross-sections, at least one control cross-section connected with an inlet channel and at least another control cross-section connected with an outlet channel, wherein the two control plate elements extend respectively with a face oriented towards a central plane of the radial cylinder block, wherein the central plane is perpendicular to the rotation axis, and the two control plate elements extend with the faces oriented towards the radial cylinder block beyond a plane which is defined by a face of the radial cylinder block, wherein the face of the radial cylinder block is oriented, towards the respective control plate element at a greatest axial width of the radial cylinder block; a plurality of pass through channels in the radial cylinder block corresponding to the plurality of bores in the radial cylinder block, wherein the pass through channels as a function of a rotational position of the cylinder block in the cam ring respectively connect the operating cavity with the control cross-section corresponding with the inlet channel or with the control cross-section corresponding with the outlet channel or are closable by a closing surface arranged at the control plate element. wherein each control plate element includes a radial bearing portion in which radial forces from the radial cylinder block are transferrable to a respective opposite radial surface in the housing or to a radial surface of a housing cover supported in the housing through a direct contact of the radial bearing portion with the radial surface, wherein the control plate element has a conical, cone ring shaped or convex spherically cambered shape, wherein a support portion of the control plate element is configured conical, conical ring shaped or convex-spherically cambered shaped, and wherein a cone angle of the control plate element is between 110° and 130°.

14. A hydrostatic radial piston machine, comprising: a housing; a radial cylinder block rotatably supported in the housing about a rotation axis and including a plurality of bores extending from an outer enveloping surface of the radial cylinder block into an interior of the radial cylinder block and arranged distributed over a circumference of the radial cylinder block; a plurality of pistons which corresponds to the plurality of bores, wherein the pistons are movably supported in the bores and respectively define an operating cavity for a hydraulic fluid together with the associated bore; a cam ring which is arranged eccentric relative to the radial cylinder block and which circumferentially envelops the radial cylinder block and wherein ends of the pistons oriented away from the radial cylinder block are movably supported at an inner enveloping surface of the cam ring during a rotation of the radial cylinder block; two control plate elements including a total of at least two control cross-sections, at least one control cross-section connected with an inlet channel and at least another control cross-section connected with an outlet channel, wherein the two control plate elements extend respectively with a face oriented towards a central plane of the radial cylinder block, wherein the central plane is perpendicular to the rotation axis, and the two control plate elements extend with the faces oriented towards the radial cylinder block beyond a plane which is defined by a face of the radial cylinder block, wherein the face of the radial cylinder block is oriented towards the respective control plate element at a greatest axial width of the radial cylinder block; a plurality of pass through channels in the radial cylinder block corresponding to the plurality of bores in the radial cylinder block, wherein the pass through channels as a function of a rotational position of the cylinder block in the cam ring respectively connect the operating cavity with the control cross-section corresponding with the inlet channel or with the control cross-section corresponding with the outlet channel or are closable by a closing surface arranged at the control plate element, wherein each control plate element includes a radial bearing portion in which radial forces from the radial cylinder block are transferrable to a respective opposite radial surface in the housing or to a radial surface of a housing cover supported in the housing through a direct contact of the radial bearing portion with the radial surface, wherein one control plate element of the two control plate elements is arranged respectively on both sides of the radial cylinder block, and wherein a first control plate element of the two control plate elements is preloaded through an undulated washer supported at the housing or at the housing cover in a direction towards a second opposite control plate element of the two control plate elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is subsequently described in more detail based on two embodiments of a radial piston machine with reference to drawing figures wherein:

(2) FIG. 1 illustrates a cross section of a first embodiment of a radial piston machine with pistons and piston rings;

(3) FIG. 2 illustrates a cross sectional view like FIG. 1, however cut in longitudinal direction;

(4) FIG. 2a illustrates an enlarged view of the redial cylinder block and the control plate elements according to FIG. 2;

(5) FIG. 3 illustrates a cross sectional view of a second embodiment of a radial piston machine with pistons shaped as beakers;

(6) FIG. 4 illustrates a view analogous to FIG. 3, however in longitudinal sectional view; and

(7) FIG. 5 illustrates a view analogous to FIG. 1, however with force vectors symbolized by arrows.

DETAILED DESCRIPTION OF THE INVENTION

(8) A radial piston machine 1 illustrated in FIGS. 1, 2 and 2a includes a housing 2 which is closed fluid tight viewed in axial direction on one side with a housing cover 3. A cam ring 4 is moveably arranged in the housing 2, thus moveable along two respective surfaces 5, 6 which are configured on one side on an inner enveloping surface 7 of the housing 2 and on the other side at an outer enveloping surface 8 of the cam ring.

(9) The radial piston machine 1 furthermore includes a rotor configured as a radial cylinder block 9 which is rotatable about a rotation axis 10. In the present case the cylinder block 9 includes nine bores 11 evenly distributed over a circumference of the radial cylinder block 9 and starting from an outer enveloping surface 12 of the radial cylinder block 9 and extending in radial direction into an interior of the radial cylinder block 9, this means towards the rotation axis 10.

(10) A piston 13 is moveably arranged in each bore 11, wherein each piston 13 includes a piston head 14 through which it is supported in a sealed manner in the bore 11 and a plate shaped piston base 15 through whose lower face 16 the respective piston 13 is supported at a spherically cambered inner enveloping surface 17 of the cam ring 4. Each piston 13 includes a pass through bore 18 extending from the piston head 14 to the piston base 15, wherein the pass through bore leads at the face 16 of the piston base 15 into a pressure cavity 19 which in turn causes a hydrostatic unloading of the support of the piston base 15 at the cam ring 4. In a known manner each piston has a circumferential groove in the portion of its piston head 14 wherein a, piston ring 20 is inserted into the groove for purposes. Between the piston head 14 and the piston base 15 there is a piston neck which is reduced in diameter, wherein the piston neck depending on the position of the piston 13 in the bore 11 facilitates tilting the longitudinal piston axis relative to the bore longitudinal axis.

(11) According to the known basic principle of radial piston machines the rotation axis 10 of the radial cylinder block 9 and the center axis of the cam ring 4 (the center axis of the cam ring is not illustrated in the drawing figure for reasons of clarity) are arranged eccentrial with respect to one another, wherein the variable amount of eccentricity defines the stroke of the pistons 13. During a complete revolution of the radial cylinder block 9 about the rotation axis 10 the pistons 13 therefore move from an upper dead center where they have moved the deepest into the bore 11 to a lower dead center where they define a maximum size operating cavity 22 together with the walls of the bore 11. The amount of the eccentricity between the radial cylinder block 9 and the cam ring 4 can be varied in the present embodiment through two hydraulic actuation cylinders whose cylinder bores 23 and 24 are arranged at opposite sides of the housing 2 and which are respectively provided with a beaker shaped piston 25, 26 that is axially moveable in the cylinder bore 23, 24. Based on the position illustrated in FIG. 1 in which the eccentricity is at a maximum the cam ring 4 can be moved to the right by a path 27 parallel to the planar surfaces 5 and 6 which reduces the eccentricity and also the feed rate of the radial piston machine to 0.

(12) In a manner that is also known in the art, hydraulic fluid is fed through a radial piston machine, which is described based on the function of a radial piston pump, in a manner where hydraulic fluid flows from an inlet channel 28 arranged in the housing 2 and angled by 90° at its radial inner end into a control channel 29 of a control plate element 30. The control plate element 30 is arranged between a housing wall 31 and the radial cylinder block 9. Another substantially identically configured control plate element 32 is arranged on the opposite side of the radial cylinder block 9 and is defined by a housing wall 33 on its side oriented away from the cylinder block 9. In both control plate elements 30, 32 the respective control channel 29, 34 is expanded in a circular segment shape in a face of the control plate element 30, 32 oriented towards the radial cylinder block 9. This known configuration facilitates that hydraulic fluid flows from the control channel 29 through a pass-through channel 35 respectively associated with each bore 11 in the radial cylinder block 9 into the respective operating cavity 22 during a suction phase extending over an angular range of approximately 150°. As soon as a piston 13 has reached its upper dead center, the flow connection between the control channel 29 associated with the inlet channel 28 and the associated pass-through channel 35 ends, whereas in the next moment a connection between the additional control channel 37 configured like the control channel 29 and associated with the outlet channel 36 is established on the “pressure side” of the control plate element 30 or the radial piston machine 1. The cross-sections of the control channels 29, 37 which are arranged in the respective separation planes between the control plate element 30 and the radial cylinder block 9 are designated as control cross-sections 29′, 37′.

(13) Due to an ongoing rotation of the radial cylinder block 9, each piston 13 pushes the hydraulic fluid arranged in the associated operating cavity 22 through the pass-through channel 35 associated with each bore 11 and the control channel 37 that is also expanded in a groove shape and extends over a circular segment of approximately 150° into the outlet channel 36. Between the control cross-sections 29′, 37′ of the control plate element 30, there are two closure surfaces offset by 180° from one another (not illustrated in the figures) which close the pass-through channels 35 respectively into two intermediary portions between the control cross-sections 29′ and 37′ in order to prevent a shorting between the suction side and the pressure side. The control plate element 32 illustrated in FIG. 2 on the right also includes a second, this means lower control channel 38 which in the present case like the upper control channel 34 of this control plate element 32 is not functional.

(14) In order to be able to feed also large volume flows on the suction side of the radial piston machine 1 without cavitation, the suction side control channel 34 of the control plate element 32 can also be connected with the inlet channel 28 as required. On the pressure side, the connection of the control channel 38 with the outlet channel 36 is hardly required. In order to have identical components, however, both control plate elements 30, 32 are respectively provided with two control channels 29, 37 and 34, 38.

(15) In order to facilitate an axial gap compensation in the portion of the control plate elements 30, 32 and of the radial cylinder block 9, there is a spring element 39, which is only schematically illustrated and configured as an undulated washer, between the housing wall 33 and the face of the control plate element 32 oriented towards the housing wall. The spring element 39, however, is not configured to apply forces that are large enough to compensate the high axially acting hydraulic forces. Thus, a pressure loaded compensation surface K is additionally provided at the face of the cover 3 oriented towards the control plate element 32. The compensation surface K is configured double kidney-shaped and corresponds on the one hand side with the suction side control channel 29 and on the other hand side with the pressure side control channel 37. Through a seal element D which is also configured kidney-shaped, a volume that corresponds to the compensation surface K is sealed between the housing cover 3 and the rear face of the control plate element 32 oriented towards the housing cover 3. This way a pressure proportional axial contact force is generated which is always only a few percent above the axial component of the hydraulic gap force at the respective control plate element 30, 32. Thus the gap compensation is provided without providing excessive forces which would only generate increased friction.

(16) Based on the enlarged illustration according to FIG. 2a, now particular features of the control plate element 30, 32 and the radial cylinder block 9 are illustrated.

(17) Both control plate elements 30, 32 respectively include a conical ring shaped support portion 40, 41 which interacts with a complementary also conical ring shaped support portion 42, 43 at the opposite faces of the radial cylinder block 9. While the control channels 29, 37 and 34, 38, this means in particular also the control cross-sections 29′, 37′, are arranged in the support portions 40, 41 of the control plate elements 30, 32, the pass through channels 35 configured as pass through bores are configured in the support portions 42 and 43 on both sides in the radial cylinder block 9.

(18) Both control plate elements 30, 32 respectively include a central pass-through bore 44, 45 through which a drive shaft 46 of the radial piston machine 1 extends. A torque coupling portion 47 of the radial cylinder block 9 is configured as an internal hexagon into which a respectively adapted external hexagon of the drive shaft 46 is inserted torque proof.

(19) Both control plate elements 30, 32 include a cylindrical support portion 48, 49 adjacent to the respective support portion 40, 41, wherein the outer enveloping surface 50, 51 is respectively supported in an adapted recess in the housing 2 or the housing cover 3. The radial cylinder block 9 includes a freewheeling portion 52, 53 adjacent in radial direction at the support portions 42 and 43 in which a respective gap 58, 59 is arranged between the respective face 54, 55 of the radial cylinder block 9 and an opposite face 56, 57 of the control plate elements 30, 32.

(20) It can be derived from FIG. 2a that an axially measured width of the radial cylinder block 9 decreases in the support portion 42, 43 towards the rotation axis 10. The greatest axial width 60 is provided in the freewheeling portions 52, 53, whereas the smallest axial width 61 is provided in the torque coupling portion 47. The cone angle of the control plate elements 30, 32 is respectively 120°, so that the trace lines of the drawing sectional plane with the control plate elements 30, 32 respectively enclose an angle of 60° with the rotation axis 10.

(21) It is furthermore visible that the control plate elements 30, 32 with their conical ring shaped faces forming the support portions 42, 43 extend over the planes formed by the faces 54, 55 of the radial cylinder block 9 in a direction towards a center plane 62 of the radial cylinder block 9, which center plane is perpendicular to the rotation axis 10.

(22) The difference of the radial piston machine 1 illustrated in FIGS. 3 and 4 is that the pistons 13′ therein have a beaker shape in longitudinal direction. A beaker edge 63 arranged in the respective piston head 14′ has a small wall thickness that is reduced towards the free end of the beaker edge 63, so that as a consequence of a pressure buildup in the operating cavity 22 of the respective bore 11 in the radial cylinder block 9, a self reinforcing sealing effect is provided. The pistons 13′ are configured as injection molded plastic components and are made e.g. from PEEK (poly ether ether ketone) or PAI (poly amide imide).

(23) The pistons 13′ are rotation symmetrical components, wherein the plastic material used facilitates an elastic form change in its contact area with the inner enveloping surface of the bore 11, when due to its slanted arrangement of the pistons 13′, the contact line in the portion of the piston head 14′ defines an ellipsis during a rotation of the radial cylinder block.

(24) In the cross-sectional illustration according to FIG. 5, eventually the different force vectors provided during operation of the radial piston machine 1 are illustrated. The radial hydraulic forces acting in the respective operating cavity 22 illustrated by the arrow P1 are hydraulically compensated according to the invention through the symmetrically slanted faces of the radial cylinder block 9 or the control plate elements 30, 32 which is illustrated by the hydraulic force vectors according to the arrows P2 and P3. Additionally the mechanical forces according to the arrows P4 are illustrated in FIG. 5, wherein the mechanical forces are reaction forces occurring in the housing 2 to balance the hydraulic forces which are transmitted from the operating cavity 22 through the pistons 26 and the cam ring 4. The forces acting in radial direction upon the control plate elements 30, 32 are transferred in their support portions 48, 49 to a respective opposite surface in the housing 2 or the housing cover 3, where reaction forces are illustrated in the form of the arrows P5.

REFERENCE NUMERALS AND DESIGNATIONS

(25) 1 radial piston machine

(26) 2 housing

(27) 3 housing cover

(28) 4 cam ring

(29) 5 planar surface

(30) 6 planar surface

(31) 7 inner enveloping surface

(32) 8 outer enveloping surface

(33) 9 radial cylinder block

(34) 10 rotation axis

(35) 11 bore

(36) 12 outer enveloping surface

(37) 13, 13′ piston

(38) 14, 14′ piston head

(39) 15 piston base

(40) 16 face

(41) 17 inner enveloping surface

(42) 18 pass through bore

(43) 19 pressure cavity

(44) 20 piston ring

(45) 21 piston neck

(46) 22 operating cavity

(47) 23 cylinder bore

(48) 24 cylinder bore

(49) 25 piston

(50) 26 piston

(51) 27 path

(52) 28 inlet channel

(53) 29 control channel

(54) 29′ control cross-section

(55) 30 control plate element

(56) 31 housing wall

(57) 32 control plate element

(58) 33 housing wall

(59) 34 control channel

(60) 35 pass through channel

(61) 36 outlet channel

(62) 37 control channel

(63) 37′ control cross-section

(64) 38 control channel

(65) 39 spring element

(66) 40 support portion

(67) 41 support portion

(68) 42 support portion

(69) 43 support portion

(70) 44 pass through bore

(71) 45 pass through bore

(72) 46 drive shaft

(73) 47 torque coupling portion

(74) 48 bearing portion

(75) 49 bearing portion

(76) 50 outer enveloping surface

(77) 51 outer enveloping surface

(78) 52 freewheeling portion

(79) 53 freewheeling portion

(80) 54 face

(81) 55 face

(82) 56 face

(83) 57 face

(84) 58 gap

(85) 59 gap

(86) 60 width

(87) 61 width

(88) 62 center plane

(89) 63 beaker edge

(90) D seal element

(91) K compensation surface

(92) P1 arrow

(93) P2 arrow

(94) P3 arrow

(95) P4 arrow

(96) P5 arrow