Hydrostatic Axial Piston Machine

• US 20190316572A1
• Filed: 04/08/2019
• Published: 10/17/2019
• Est. Priority Date: 04/11/2018
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Nafz, Timo
• Granted Patent: US 11,002,244 B2
• Time in Patent Office: Days
• CPC Class Codes: F03C 1/0605 Adaptations of pistons pump pistons F04B1/124, F04B53/14
• CPC Class Codes: F03C 1/0644 Component parts
• CPC Class Codes: F03C 1/0671 Swash or actuated plate bearing means or driven axis bearing means
• CPC Class Codes: F03C 1/0686 by changing the inclination of the swash plate
• CPC Class Codes: F04B 1/126 Piston shoe retaining means
• CPC Class Codes: F04B 1/128 Driving means
• CPC Class Codes: F04B 1/20 having rotary cylinder block
• CPC Class Codes: F04B 1/2007 Arrangements for pressing the cylinder barrel against the valve plate, e.g. by fluid pressure
• CPC Class Codes: F04B 1/2035 Cylinder barrels
• CPC Class Codes: F04B 1/2078 Swash plates
• CPC Class Codes: F04B 1/2085 Bearings for swash plates or driving axles
• CPC Class Codes: F04B 1/324 by changing the inclination of the swash plate

Abstract

A hydrostatic axial piston machine includes a housing, a connection plate closing the housing, working connections formed on the connection plate, a drive shaft, a swashplate, a cylinder drum coupled to the shaft in the direction of rotation, bores formed in the drum and each including a piston, a control plate against which the drum bears, a retraction plate for removing a piston from the bores, and a retraction ball arranged in front of the first end face of the drum which surrounds a drum neck of the drum and the shaft and by which the retraction plate is loaded in the direction of the swashplate. A pressure chamber is defined by seals between the retraction ball, the drum, and the shaft, and is configured to be acted upon by a pressure above a housing pressure. The retraction ball is sealed against the drum neck and against the shaft.

Claims

1. A swashplate-type hydrostatic axial piston machine, comprising:

a housing;

a connection plate that closes the housing;

a plurality of working connections formed on the connection plate;

a drive shaft rotatably mounted in the housing and in the connection plate;

a swashplate;

a cylinder drum coupled to the drive shaft in a direction of rotation and including a first end face, a second end face, and a drum neck;

a plurality of cylinder bores defined in the cylinder drum; and

a plurality of displacement pistons, each of which is located in an associated one of the plurality of cylinder bores and is movable back and forth in the associated cylinder bore, each displacement piston projecting on the first end face from the cylinder drum and resting against the swashplate;

a control plate against which the second end face bears;

a retraction plate configured to remove each displacement piston from the plurality of cylinder bores on one half of a rotation; and

a retraction ball arranged in front of the first end face surrounding the drum neck and the drive shaft, the retraction plate loaded in a direction of the swashplate via the retraction ball,

wherein the retraction ball is sealed against the drum neck of the cylinder drum and against the drive shaft,

wherein a retraction ball pressure chamber is defined by a plurality of seals between the retraction ball, the cylinder drum, and the drive shaft, and is configured to be acted upon by a pressure above a housing pressure,

wherein the plurality of cylinder bores are fluidically open in respect of the control plate, and

wherein the plurality of cylinder bores are configured to be connected fluidically to the plurality of working connections via the control plate.

2. The hydrostatic axial piston machine according to claim 1, wherein a sealing diameter of a first seal of the plurality of seals arranged between the drum neck and the retraction ball is greater than a surface diameter of a sealing surface lying towards the drive shaft between the cylinder drum and the control plate.

3. The hydrostatic axial piston machine according to claim 1, wherein the retraction ball pressure chamber is connected to an external pressure connection via a fluid path.

4. The hydrostatic axial piston machine according to claim 3, wherein the external pressure connection is located on the connection plate and the fluid path leads from the external pressure connection through the connection plate into the retraction ball pressure chamber.

5. The hydrostatic axial piston machine according to claim 1, wherein:

the hydrostatic axial piston machine includes a high-pressure side and a low-pressure side; and

the retraction ball pressure chamber is connected to the high-pressure side via a fluid path.

6. The hydrostatic axial piston machine according to claim 2, wherein the first seal between the retraction ball and the drum neck includes a sealing ring inserted into an annular groove defined on the drum neck and bears against the retraction ball.

7. The hydrostatic axial piston machine according to claim 1, wherein:

a second seal of the plurality of seals is arranged between the retraction ball and the drive shaft and includes a sealing ring inserted into an annular groove defined on the drive shaft; and

the sealing ring bears against the retraction ball.

8. The hydrostatic axial piston machine according to claim 1, wherein:

the drive shaft is rotatably mounted in the connection plate on a side of the control plate opposite the cylinder drum via a bearing; and

the bearing is configured as a sealing point.

9. The hydrostatic axial piston machine according to claim 8, wherein leakage flowing into a space in front of an end face of the drive shaft projecting into the connection plate is diverted by a fluid path.

10. The hydrostatic axial piston machine according to claim 8, wherein the bearing is a slide bearing configured as a bearing bush.

11. The hydrostatic axial piston machine according to claim 10, wherein sliding surfaces of a pair of sliding surfaces are smoothly configured between the bearing bush and the drive shaft without any interruption.

12. The hydrostatic axial piston machine according to claim 1, wherein the hydrostatic axial piston machine is configured as a vibration drive, the axial piston machine further comprising:

a plurality of grooves arranged concentrically to one another running around 360°

in a rotary feed-through between the cylinder drum and the control plate,

wherein each groove of the plurality of grooves is permanently fluidically connected to a cylinder bore of the plurality of cylinder bores and to a working connection of the plurality of working connections.

13. The hydrostatic axial piston machine according to claim 1, where in the hydrostatic axial piston machine is a hydrostatic axial piston pump.