Hydrostatic axial piston machine

Patent metadata

Field	Value
Publication number	US-10760554-B2
Application number	US-201916375025-A
Country	US
Kind code	B2
Filing date	Apr 4, 2019
Priority date	Apr 4, 2018
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

A hydrostatic axial piston machine includes a cylinder drum having a substantially hollow cylindrical base body, and liners. The body includes cylinder bores located around a central axis. The liners have an outer diameter press-fitted into the bores such that an outer end face of each liner is positioned in a region of an opening of a respective bore, and such that an inner end face of each liner is positioned deep within the respective bore. An outer half of each liner, starting from the outer end face, includes an axially delimited circumferential recess in an outer casing surface of the liner. The machine is configured to operate with great forces acting between the liners and displacement pistons. The recess in each liner is shaped such that, in an axial section through the liner enclosing an axis of the liner, a depth of the recess increases more than once and decreases more than once.

First claim

What is claimed is:

1. A hydrostatic axial piston machine, comprising:
a cylinder drum, including:
a substantially hollow cylindrical base body having a plurality of cylinder bores arranged around a central axis; and
a plurality of liners, each liner configured to guide a respective displacement piston, each liner having:
a fitting outer diameter pressed into a respective cylinder bore;
an outer end face positioned in a region of an opening of the respective cylinder bore;
an inner end face positioned inside the respective cylinder bore;
an outer casing surface; and
an axially delimited circumferential recess region in the outer casing surface, the recess region located in an outer half of the liner starting from the outer end face, and the recess region shaped such that in an axial section through the liner enclosing an axis of the liner, a depth of the recess region increases more than once and decreases more than once.

2. The hydrostatic axial piston machine of claim 1 , wherein the recess region includes a recess having a protrusion that ends below the fitting outer diameter of the liner.

3. The hydrostatic axial piston machine of claim 2 , wherein a highest point of the protrusion is pointed or linear.

4. The hydrostatic axial piston machine of claim 2 , wherein the recess has a base that is curved, at least in regions, with a curvature that is greater than zero and less than infinity.

5. The hydrostatic axial piston machine of claim 4 , wherein the protrusion extends over a portion of a width of the recess, the portion being between 70% and 85% of the width of the recess.

6. The hydrostatic axial piston machine of claim 4 , wherein:
the base of the recess, starting from an edge lying on the fitting outer diameter of the liner, falls away to a lowest point following a first circle arc that is concave toward the fitting outer diameter and that has a first radius;
from the lowest point, the base continues following a second circle arc that is convex toward the fitting outer diameter, that has a second radius, and that adjoins the first circle arc with a constant tangent; and
the first radius of the first circle arc is approximately 2 mm, and the second radius of the second circle arc is between 20 mm and 60 mm.

7. The hydrostatic axial piston machine of claim 2 , wherein the protrusion is centered within the recess.

8. The hydrostatic axial piston machine of claim 2 , wherein the recess runs in a ring-like manner around the liner, and has a same contour in each axial section enclosing the axis of the liner.

9. The hydrostatic axial piston machine of claim 1 , wherein the recess region includes a plurality of individual recesses that are separated from each other by faces or edges lying on the fitting outer diameter of the liner.

10. The hydrostatic axial piston machine of claim 9 , wherein the plurality of individual recesses are arranged successively in a direction of the axis of the liner.

11. The hydrostatic axial piston machine of claim 10 , wherein the plurality of individual recesses run in a ring-like manner around the liner, each of the plurality of individual recesses having a same contour in each axial section enclosing the axis of the liner.

12. The hydrostatic axial piston machine of claim 9 , wherein:
a first recess of the plurality of individual recesses is a main recess and has a first dimension in a direction of the axis of the liner;
at least one further recess in the plurality of individual recesses is at least one secondary recess that directly follows the main recess in the direction of the axis of the liner, and that has a second dimension in the direction along the axis of the liner that is smaller than the first dimension.

13. The hydrostatic axial piston machine of claim 12 , wherein:
the main recess includes a protrusion that ends below the fitting outer diameter of the liner; and
the at least one secondary recess, in an axial section enclosing the axis of the liner, has a circle-arced contour in which a depth of the secondary recess increases only once and decreases only once.

14. The hydrostatic axial piston machine of claim 12 , wherein a respective secondary recess is located on each side of the main recess.

15. The hydrostatic axial piston machine of claim 14 , wherein the respective secondary recesses on each side of the main recess have a same shape.

16. The hydrostatic axial piston machine of claim 10 , wherein two of the plurality of individual recesses have different maximal depths.

17. The hydrostatic axial piston machine of claim 1 , wherein:
the recess region includes:
a central main recess running in a ring-like manner around the liner, the central main recess having ring faces lying on the fitting outer diameter of the liner; and
a respective secondary recess positioned on each side of the central main recess, each secondary recess running in a ring-like manner around the liner, the respective secondary recesses separated by the ring faces of the central main recess
the main recess is wider than the respective secondary recesses;
the main central recess includes a protrusion that ends below the fitting outer diameter of the liner, and that is positioned in a middle of the main central recess; and
the respective secondary recesses are shaped such that a depth of the respective secondary recesses only increases once and only decreases once.

18. The hydrostatic axial piston machine of claim 17 , wherein:
at a location between the protrusion and one of the ring faces, the central main recess has a maximal depth that is greater than a maximal depth of the respective secondary recesses; and
a minimal depth of the central main recess, at a highest point of the protrusion, is smaller than the maximal depth of the respective secondary recesses.

19. The hydrostatic axial piston machine of claim 17 , wherein:
at a location between the protrusion and one of the ring faces, the central main recess has a maximal depth that is greater than a maximal depth of the respective secondary recesses; and
the central main recess and the respective secondary recesses each fall away from the ring face following a contour defined by a common mathematical formula, at first steeply, and then flatly to a corresponding maximal depth.

20. The hydrostatic axial machine of claim 4 , wherein an entirety of the base of the recess including the protrusion is formed without edges and without straight sections.

Assignees

• Bosch Gmbh Robert

Inventors

• Hoppe Stefan
• Nafz Timo

Classifications

• F04B1/20 Primary

  having rotary cylinder block · CPC title

• F04B1/2035 Primary

  Cylinder barrels · CPC title

• F04B53/166

  Cylinder liners · CPC title

• F04B53/16

  Casings; Cylinders; Cylinder liners or heads; Fluid connections · CPC title

• F04B1/124

  Pistons · CPC title