Hydrostatic axial piston machine

Abstract

A hydrostatic axial piston machine includes a housing and a pivot cradle. At least one slide bearing of the pivot cradle on a high-pressure side is hydrostatically relieved. The slide bearing includes one or two pairs of relief grooves. A relief pressure field develops about and between the one or two pairs of relief grooves as the grooves are supplied with relief pressure medium on one side and are closed at their outer ends. An optional slide bearing on a low-pressure side has one or two limiting grooves which delimit the relief pressure field there, as the limiting grooves are open at their outer ends.

Claims

1. A hydrostatic axial piston machine, comprising: a housing; and a pivot cradle configured to adjust a stroke volume and mounted in the housing via a slide bearing, the slide bearing having a first pair of bearing faces and a second pair of bearing faces, a bearing face of at least the first pair of bearing faces including a depression, wherein at least two hydrostatic relief grooves spaced apart from one another extend from the depression in a circumferential direction of the bearing face such that the at least two hydrostatic relief grooves are configured to be exposed to the same relief pressure, wherein the depression and the at least two hydrostatic relief grooves form a part of a first pressure relief field, wherein (i) the at least two hydrostatic relief grooves are closed at two end portions of the at least two hydrostatic relief grooves spaced apart from one another oriented in a circumferential direction, and/or (ii) a partial region of the bearing face is arranged between the two end portions of the at least two hydrostatic relief grooves spaced apart from one another oriented in the circumferential direction, and wherein the depression includes an extension in the circumferential direction which is greater than a width of the at least two hydrostatic relief grooves.

2. The hydrostatic axial piston machine according to claim 1, further comprising: at least two second relief grooves extending from the depression against the circumferential direction, wherein (i) the at least two second relief grooves are closed at two second end portions of the at least two second relief grooves spaced apart from one another oriented against the circumferential direction and/or (ii) a further partial region of the bearing face is arranged between the two second end portions of the at least two second relief grooves spaced apart from one another against the circumferential direction.

3. The hydrostatic axial piston machine according to claim 2, wherein the depression is deeper than the at least two hydrostatic relief grooves and the at least two second relief grooves.

4. The hydrostatic axial piston machine according to claim 2, wherein the depression is fluidically connected to a pressure medium channel arranged on a housing side.

5. The hydrostatic axial piston machine according to claim 4, wherein: a further bearing face on the housing side is formed on a bearing shell, the bearing shell fastened to the housing via a screw; and a portion of the pressure medium channel is arranged in the screw.

6. The hydrostatic axial piston machine according to claim 4, wherein the at least two hydrostatic relief grooves, the at least two second relief grooves, and the depression are arranged on the bearing face of the first pair of bearing faces on a pivot cradle side.

7. The hydrostatic axial piston machine according to claim 1, wherein the depression is fluidically connected to a pressure medium channel arranged on a pivot cradle side.

8. The hydrostatic axial piston machine according to claim 7, wherein the pressure medium channel is configured to be connected to cylinder chambers.

9. The hydrostatic axial piston machine according to claim 7, wherein: the second pair of bearing faces includes a second relief pressure field; and a second pressure medium channel opens into the second relief pressure field.

10. The hydrostatic axial piston machine according to claim 9, further comprising: a first limiting groove and a second limiting groove delimiting the second relief pressure field, wherein the first and second limiting grooves are spaced apart from one another in a second bearing face of the second pair of bearing faces and connected to an inner chamber of the housing via an opening.

11. The hydrostatic axial piston machine according to claim 10, wherein: the first limiting groove starting from the second relief pressure field extends in a circumferential direction; the second limiting groove starting from the second relief pressure field extends against the circumferential direction; and the first and second limiting grooves are connected to the inner chamber at end portions of the first and second limiting grooves pointing away from one another.

12. The hydrostatic axial piston machine according to claim 10, wherein the second limiting groove is longer than the first limiting groove.

13. A hydrostatic axial piston machine, comprising: a housing; and a pivot cradle configured to adjust a stroke volume and mounted in the housing via a slide bearing, the slide bearing having a first pair of bearing faces and a second pair of bearing faces, a bearing face of at least the first pair of bearing faces including a depression, wherein at least two hydrostatic relief grooves spaced apart from one another extend from the depression in a circumferential direction of the bearing face such that the at least two hydrostatic relief grooves are configured to be exposed to the same relief pressure, wherein the depression and the at least two hydrostatic relief grooves form a part of a first pressure relief field, wherein (i) the at least two hydrostatic relief grooves are closed at two end portions of the at least two hydrostatic relief grooves spaced apart from one another oriented in a circumferential direction, and/or (ii) a partial region of the bearing face is arranged between the two end portions of the at least two hydrostatic relief grooves spaced apart from one another oriented in the circumferential direction, wherein at least two second relief grooves extend from the depression against the circumferential direction, wherein (i) the at least two second relief grooves are closed at two second end portions of the at least two second relief grooves spaced apart from one another oriented against the circumferential direction and/or (ii) a further partial region of the bearing face is arranged between the two second end portions of the at least two second relief grooves spaced apart from one another against the circumferential direction, and wherein the at least two second relief grooves are longer than the at least two hydrostatic relief grooves.

14. A hydrostatic axial piston machine, comprising: a housing; and a pivot cradle configured to adjust a stroke volume and mounted in the housing via a slide bearing, the slide bearing having a first pair of bearing faces and a second pair of bearing faces, a bearing face of at least the first pair of bearing faces including a depression, wherein at least two hydrostatic relief grooves spaced apart from one another extend from the depression in a circumferential direction of the bearing face such that the at least two hydrostatic relief grooves are configured to be exposed to the same relief pressure, wherein the depression and the at least two hydrostatic relief grooves form a part of a first pressure relief field, wherein (i) the at least two hydrostatic relief grooves are closed at two end portions of the at least two hydrostatic relief grooves spaced apart from one another oriented in a circumferential direction, and/or (ii) a partial region of the bearing face is arranged between the two end portions of the at least two hydrostatic relief grooves spaced apart from one another oriented in the circumferential direction, wherein the depression is fluidically connected to a pressure medium channel arranged on a housing side, wherein the at least two hydrostatic relief grooves and the depression are arranged on the bearing face of the first pair of bearing faces on a pivot cradle side, and wherein an extension of the depression in the circumferential direction is configured such that the pressure medium channel always opens into the depression.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment of an axial piston machine according to the disclosure is depicted in the drawings. The disclosure will now be explained in greater detail with the help of the figures in these drawings.

(2) In the drawings:

(3) FIG. 1 shows a longitudinal section of the exemplary embodiment of the axial piston machine according to the disclosure;

(4) FIG. 2 shows a view of the pivot cradle of the axial piston machine from FIG. 1;

(5) FIG. 3 shows a first section of the pivot cradle from FIG. 2;

(6) FIG. 4 shows a second section of the pivot cradle from FIG. 2; and

(7) FIG. 5 shows a partial section view of the pivot cradle supported on a bearing shell of the axial piston machine from FIG. 1.

DETAILED DESCRIPTION

(8) FIG. 1 shows a longitudinal section of the exemplary embodiment of the axial piston machine according to the disclosure. It is designed in terms of its conveying volume as a one-quadrant pump and, for this purpose, has a pivot cradle 1 and a cylinder drum 2, in each of the cylinder chambers 4 whereof pistons 6 are guided, the piston feet whereof being guided along the pivot cradle 1 via piston shoes 8. The pivot cradle 1 and the cylinder drum 2 have a drive shaft 10 passing through them, wherein with zero-stroke operation of the axial piston machine, the swashplate 1 is positioned perpendicular to the drive shaft 10. So that during each rotation of the cylinder drum 2 with the drive shaft 10 a lifting movement of the pistons 6 can be generated in the respective cylinder chambers 4, the pivot cradle 1 is pivoted via an adjusting device 12 (e.g. into the oblique position shown in FIG. 1).

(9) In order to facilitate the corresponding relative movement between the pivot cradle 1 and a housing 14 of the axial piston machine during pivoting, a first and a second arcuate slide bearing are provided between the pivot cradle 1 and the housing 14. The first slide bearing is arranged above the drawing plane in FIG. 1 and is therefore only drawn in dotted lines. The second slide bearing is arranged below the drawing plane and is not shown.

(10) The first slide bearing has a first concave bearing face 16 on the pivot cradle side which is supported on a first convex bearing face 18 on the housing side. The bearing face 16 on the pivot cradle side is formed straight on the pivot cradle, while the bearing face 18 on the housing side is configured on a bearing shell 54 which is fastened to the housing 14 by a screw 56 as shown in FIG. 5.

(11) An opening 20 of a pressure medium channel 22 is provided in the screw 56 as shown in FIG. 5. Relief pressure medium is removed from a kidney-shaped high-pressure opening 24 in a distributor plate 26 via the pressure medium channel 22. Consequently, during operation of the axial piston machine, relief pressure medium for hydrostatic relief is always supplied via the pressure medium channel 22 and via the opening 20 which is formed between the two bearing faces 16, 18 and which is explained more accurately with reference to the following figures.

(12) The second slide bearing also has a second bearing face on the pivot cradle side and a second bearing face on the housing side. The second slide bearing also has hydrostatic relief with a pressure medium channel and an opening.

(13) During operation of the one-quadrant pump, a direction of rotation is assumed which means that the piston 6 is exposed to high pressure in the region above the drawing plane and to low pressure in the region below the drawing plane in FIG. 1. This means that the first slide bearing (depicted using dotted lines in FIG. 1) is the slide bearing on the high-pressure side and is therefore exposed to greater forces than the second slide bearing.

(14) FIG. 2 shows a view of the pivot cradle 1 of the axial piston machine from FIG. 1. In this case, the concave first bearing face 16 on the pivot cradle side from FIG. 1 and, moreover, also the second bearing face 28 on the pivot cradle side are depicted. In the assembled state of the axial piston machine, the respective bearing shells on the housing side with their bearing faces are arranged above the plane of projection of the two bearing faces 16, 28 on the pivot cradle side, of which bearing faces only bearing face 18 is depicted in FIG. 1. The respective opening 20, 30 for the supply of relief pressure medium for the respective hydrostatic relief is arranged in these bearing shells or bearing faces 18 (depicted using dotted lines in FIG. 2). Since the exemplary embodiment of the axial piston machine shown is designed as a one-quadrant pump, the pistons 6 exposed to high pressure are always largely supported on the first bearing face 16 on the pivot cradle side (on the right in FIG. 2), while the piston exposed to low pressure is always largely supported on the second bearing face 28 on the pivot cradle side.

(15) Since the pivot cradle 1 in FIG. 2 is shown in its central zero-stroke position, the two openings 20, 30 are arranged in a central position in each case with respect to the bearing faces 16, 28. Since the one-quadrant pump is only pivotable on one side, the openings 20, 30 can only be moved downward relative to the pivot cradle 1 from the position shown in FIG. 2. To be more precise, the bearing faces 16, 28 move through upward during the pivoting-out in FIG. 2 and below the two openings 20, 30.

(16) A first relief pressure field 32 on the high-pressure side develops about the first opening 20, while a second relief pressure field 34 on the low-pressure side develops about the second opening 30. The first relief pressure field 32 is fed via a roughly rectangular depression 36, the extension 38 whereof in the circumferential direction being greater than the maximum path covered by the first opening 20 relative to the pivot cradle 1. In this way, the first opening 20 is always fluidically connected to the depression 36.

(17) On the short side of the depression 36 (the lower side in FIG. 2), two relief grooves 40 extend in a first circumferential direction, while from the short side of the depression 36 (upper side in FIG. 2), two second relief grooves 42 extend toward the circumferential direction. The first two relief grooves 40 and the second two relief grooves 42 are each parallel to one another. On each of their outer end portions 44 facing away from the depression 36, the relief grooves 40, 42 are bent and flattened. This means that the relief grooves 40, 42 are to a certain extent fluidically closed at their end portions 44. This means that a partial region of the bearing face remains between the two end portions 44 of each pair of relief grooves 40, 42, which bearing face has no recess and is used for the mechanical support of the first bearing face 16 on the pivot cradle side in relation to the first bearing face 18 on the housing side (cf. FIG. 1).

(18) The first two relief grooves 40 are shorter than the second two relief grooves 42. This means that the relief pressure of the opening 20 is distributed over the depression 36 and the four grooves 40, 42 between the first bearing face 16, 18 and also extends over the surrounding regions of the bearing face, in particular between the pairs of relief grooves 40, 42. The relief grooves 40, 42 each have a width 45 that extends roughly perpendicular to the circumferential direction. The extension 38 of the depression 36 in the circumferential direction is greater than the width 45 of the relief grooves 40, 42.

(19) On the second bearing face 28 on the pivot cradle side which supports the side of the pivot cradle 1 along which the pistons 6 exposed to low pressure run, the hydrostatic relief is smaller and weaker. The second relief pressure field 34 is created around the second opening 30 in the bearing face of the second bearing faces 28. The size of the second relief pressure field 34 is limited by a first limiting groove 46 and a second limiting groove 48. In this case, both limiting grooves 46, 48 have an opening 50 on their respective end portion spaced apart from the second relief pressure field 34. By this means, the respective limiting groove 46, 48 is connected to the inner chamber of the housing 14 (cf. FIG. 1) and therefore relieved.

(20) Since the pivot cradle 1 shownas explained aboveis only designed to pivot in one direction, the two limiting grooves 46, 48 and the relief pressure field 34 defined therebetween are asymmetrical. To be more precise, the first limiting groove 46 which extends in the circumferential direction (downward in FIG. 2) is shorter than the second limiting groove 48 which extends against the circumferential direction. This means that in the central position of the pivot cradle 1 shown in FIG. 2, the relief pressure field 34 extends predominantly in the circumferential direction (downward in FIG. 2). The spacing of the two limiting grooves 46, 48 is sufficiently great for the second opening 30 to remain adjacent to the second relief pressure field 34 formed in the bearing face, even with complete pivoting of the pivot cradle 1.

(21) FIG. 3 shows a cross section through the pivot cradle from FIG. 2 in the region of its first bearing face 16. In this case, the sectional plane is positioned through one of the first two shorter relief grooves 40 and, accordingly, one of the second two longer relief grooves 42. This means that the sectional plane also runs through the depression 36. It can be seen that the depression 36 is deeper than the two relief grooves 40, 42. Furthermore, it is shown that a bend is formed on each of the two end portions 44 of the relief grooves 40, 42 which corresponds to an arc of the disk-milling cutter used. The relief grooves 40, 42 are closed at these end portions 44.

(22) FIG. 4 shows a similar cross section through the pivot cradle 1, wherein the sectional plane lies in the limiting grooves 46, 48 of the second bearing face 28. It can be seen that the limiting grooves 46, 48 have openings 50 at their outer end portions, so that the limiting grooves 46, 48 are relieved and therefore delimit the second relief pressure field 34 arranged between them. Bends 52 can be seen in the transition between the relief pressure field 34 and the limiting grooves 46, 48 which likewise correspond to the arc of the disk-milling cutter used.

(23) All recesses 36, 40, 42, 46, 48 shown in FIGS. 3 and 4 can be produced using the aforementioned disk-milling cutter, wherein this can always be guided parallel to the sectional planes or in the sectional planes in FIGS. 3 and 4 and need not be pivoted or tilted in respect thereof.

(24) Unlike in the exemplary embodiment shown, the axial piston machine may also be freely pivotable, in which case in the central position of the pivot cradle 1 shown in FIG. 2, the depression 36 is central below the first opening 20 and the first relief grooves 40 are as long as the second relief grooves 42. With regard to the second bearing shell 28 on the pivot cradle side, the second relief pressure field 34 is arranged centrally below the second opening 30 and the first limiting groove 46 is as long as the second limiting groove 48.

(25) Unlike in the exemplary embodiment described, the relief grooves and the depressions and limiting grooves can also be directly introduced into the bearing faces on the pivot cradle side (e.g. forging or casting) without the disk-milling cutter.

(26) A hydrostatic axial piston machine with a pivot cradle is disclosed, wherein at least one slide bearing of the pivot cradle on the high-pressure side is hydrostatically relieved. For this purpose, the slide bearing has one or two pairs of relief grooves, about which and between which a relief pressure field develops, as the grooves are supplied with relief pressure medium on one side and are closed at their outer ends. An optional slide bearing on the low-pressure side has one or two limiting grooves which delimit the relief pressure field there, as the limiting grooves are open at their outer ends, for example.

LIST OF REFERENCE NUMBERS

(27) 1 Pivot cradle 2 Cylinder drum 4 Cylinder chamber 6 Piston 8 Piston shoe 10 Drive shaft 12 Adjusting device 14 Housing 16 First bearing face on the pivot cradle side 18 First bearing face on the housing side 20 First opening 22 Pressure medium channel 24 High-pressure opening 26 Distributor plate 28 Second bearing face on the pivot cradle side 30 Second opening 32 First relief pressure field 34 Second relief pressure field 36 Depression 38 Extension 40 First relieving groove 42 Second relieving groove 44 End portion/bend 46 First limiting groove 48 Second limiting groove 50 Opening 52 Bend