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EP-4737721-A1 - COMPRESSION RING FOR A PISTON SLIPPER ARRANGEMENT, PISTON SLIPPER ARRANGEMENT, AND AXIAL PISTON MACHINE

EP4737721A1EP 4737721 A1EP4737721 A1EP 4737721A1EP-4737721-A1

Abstract

The present invention relates to a compression ring (6) for a piston slipper arrangement (2), wherein the piston slipper arrangement (2) comprises a piston slipper body (3) and a ceramic sliding element (7) and is configured to be provided in an axial piston machine, wherein the compression ring (6) is configured to compress the ceramic sliding element (7). The objective of the present invention is to provide a compression ring (6) which allows an easy assembly of a piston slipper arrangement (2). This objective is solved by a compression ring (6) that comprises first engagement means (8) configured for engaging with corresponding second engagement means (9) of the piston slipper body (3) in order to limit rotation of the compression ring (6) relative to the piston slipper body (3). The invention further relates to a piston slipper arrangement and to an axial piston machine,

Inventors

  • ANDERSEN, STIG KILDEGAARD
  • Kolb, Tommi

Assignees

  • Danfoss A/S

Dates

Publication Date
20260506
Application Date
20241029

Claims (14)

  1. A compression ring (6) for a piston slipper arrangement (2), wherein the piston slipper arrangement (2) comprises a piston slipper body (3) and a ceramic sliding element (7) and is configured to be provided in an axial piston machine, wherein the compression ring (6) is configured to compress the ceramic sliding element (7), characterized in that the compression ring (6) comprises first engagement means (8) configured for engaging with second engagement means (9) of the piston slipper body (3) in order to limit rotation of the compression ring (6) relative to the piston slipper body (3).
  2. The compression ring (6) according to claim 1, wherein the first engagement means (8) include at least one protruding element (8).
  3. The compression ring (6) according to claim 1 or 2, wherein the first engagement means include at least one protrusion (8), preferably at least three protrusions (8), protruding in an axial direction of the compression ring (6).
  4. The compression ring (6) according to claim 3, wherein each protrusion (8) comprises at least one contact surface (8-1, 8-2) having a normal vector that is parallel to a local circumferential direction of the compression ring (6).
  5. The compression ring (6) according to any one of the preceding claims, wherein the first engagement means (8) are configured to provide a centering functionality for centering the compression ring (6) relative to the piston slipper body (3) with regard to a central axis (CA) of the compression ring (6).
  6. The compression ring (6) according to any one of the preceding claims, wherein the first engagement means are configured to provide a retaining functionality for detachably axially retaining the compression ring (6) relative to the piston slipper body (3).
  7. A piston slipper arrangement (2) having a piston slipper body (3), a compression ring (6) and a ceramic sliding element (7), wherein the compression ring (6) compresses the ceramic sliding element (7), wherein the compression ring (6) and the ceramic sliding element (7) form a sliding unit (5), characterized in that the compression ring (6) is formed according to any one of the preceding claims and that the piston slipper body (3) comprises the second engagement means (9).
  8. The piston slipper arrangement (2) according to claim 7, wherein the first engagement means comprises at least three protrusions (8) protruding in the axial direction and wherein the second engagement means comprises a corresponding number of recesses (9).
  9. The piston slipper arrangement (2) according to claim 7 or 8, characterized in that the piston slipper arrangement (2) comprises an axial sealing element (12) which seals the piston slipper body (3) against an axial end face of the ceramic sliding element (7).
  10. The piston slipper arrangement (2) according any one of the claim 7 to 9, characterized in that the ceramic sliding element (7) is annular and the piston slipper arrangement (2) comprises a radial sealing element (10) which seals the piston slipper body (3) against an inner circumferential surface of the ceramic sliding element (7).
  11. The piston slipper arrangement (2) according to any one of the claims 7 to 10, characterized in that the sliding unit (5) is detachably retained to the piston slipper body (3).
  12. The piston slipper arrangement (2) according to claims 10 and 11, characterized in that radial sealing element (10) serves as means for detachably retaining the sliding unit (5) to the piston slipper body (3).
  13. The piston slipper arrangement (2) according to any one of the claims 7 to 12, characterized in that the ceramic sliding element (7) extends in its axial direction beyond the piston slipper body (3) and the compression ring (6).
  14. An axial piston machine comprising a piston slipper arrangement (2) according to any one of the claims 7 to 13.

Description

The present invention relates to a compression ring for a piston slipper arrangement, wherein the piston slipper arrangement comprises a piston slipper body and a ceramic sliding element and is configured to be provided in an axial piston machine, wherein the compression ring is configured to compress the ceramic sliding element of the piston slipper arrangement. Further, the invention relates to a piston slipper arrangement having a piston slipper body, a compression ring, and a ceramic sliding element, wherein the compression ring is configured to compress the ceramic sliding element, wherein the compression ring and the ceramic sliding element form a sliding unit. Further, the invention relates to an axial piston machine having such a piston slipper arrangement. An axial piston machine is for example a hydraulic (positive displacement) pump or motor. The axial piston machine comprises pistons, which reciprocate within respective cylinders, wherein the cylinders are provided in a block. The block rotates relative to a swash plate or vice versa, wherein the swash plate and the block are arranged at an angle to each other. The piston is in contact with the swash plate via a piston slipper arrangement. The piston slipper arrangement is coupled to the swash plate via a ceramic sliding element. Such a ceramic sliding element has a high resistance against pressure but can easily be damaged by pulling forces. Therefore, the ceramic sliding element is compressed via a compression ring. The compression ring is formed of a metal, in particular a steel, stainless steel, or the like. To assemble the sliding unit, the compression ring is heated such that it expands. When the compression ring is sufficiently heated and thus expanded, it is placed around the ceramic sliding element. When the compression ring cools down and shrinks, it compresses the ceramic sliding element. The ceramic sliding element and the compression ring form together a sliding unit. The sliding unit is mounted to the piston slipper body. In the state of the art, the sliding unit is attached to the piston slipper body by means of an adhesive. However, it is difficult to verify that the adhesive bond of the sliding unit to the piston slipper body meets the predefined requirement in a non-destructive manner. Furthermore, it is difficult to orient and fix the sliding unit relative to the piston slipper body in a predefined manner. The problem to be solved is to provide a compression ring which can be easily mounted and oriented onto the piston slipper body. This problem is solved by a compression ring according to claim 1. The compression ring is for a piston slipper arrangement, wherein the piston slipper arrangement comprises a piston slipper body and a ceramic sliding element (with second engagement means) and is configured to be provided in an axial piston machine, wherein the compression ring is configured to compress the ceramic sliding element. The compression ring comprises first engagement means configured for engaging with (the) second engagement means of the piston slipper body in order to limit rotation of the compression ring relative to the piston slipper body. In particular, the first engagement means may be configured for mechanically engaging with the corresponding second engagement means, e.g. due to a form-fit. Additionally or alternatively, the first engagement means may be configured for magnetically engaging with the corresponding second engagement means. For example, the first engagement means comprise at least one protruding element. The second engagement means may comprise at least one corresponding recess. The protruding element may protrude axially, radially outwardly, and/or radially inwardly from the compression ring. Protrusions, spline ridges, and/or teeth may be considered protruding elements. The compression ring may be annular. It might extend about a central axis. An axial direction might be parallel to the central axis (and vice versa). The compression ring may have an inner circumferential surface and an outer circumferential surface. It can have a first end face in the axial direction. The first end face may be configured to face the piston shoe assembly. I can have a second end face in the axial direction. The second end face may be configured to face towards the swash plate of the axial piston machine. If the piston slipper assembly is installed in the axial piston assembly, there might however remain a (small) gap between the second end face of the compression ring and the swash plate. According to one aspect, the first engagement means can, for example, include one of, several of, or all of the following: at least one a protrusion (especially several protrusions, e.g. at least three protrusions),at least one tooth (especially several teeth), e.g. at least one axial tooth and/or at least one radial tooth,at least one spline element (a spline ridge / a spline groove),at least one groove, andthe like. Outer splin