Actuating Cylinder for a Hydrostatic Axial Piston Machine and Hydrostatic Axial Piston Machine with an Actuating Cylinder

Abstract

An actuating cylinder for an adjustment apparatus of a pivot angle of a hydrostatic axial piston machine has a hydraulic stop which connects an actuating pressure chamber of the actuating cylinder to an interior of the housing of the axial piston machine if the actuating piston is maximally extended. To this end, a channel is provided on the actuating piston side, while a control edge is provided on the housing side. The control edge is formed at the interface of a stop bore with the actuating cylinder bore. The stop bore may also be a leakage bore of the axial piston machine.

Claims

1. An actuating cylinder for adjusting a stroke volume of a hydrostatic axial piston machine, comprising: an actuating cylinder bore defined in a main component; and an actuating piston movably guided in the actuating cylinder bore, the actuating piston defining an actuating pressure chamber, the actuating piston having a hydraulic stop for the actuating piston at which the actuating pressure chamber is connected via at least one channel to a surrounding area of the actuating cylinder, the hydraulic stop including a stop bore defined in the main component and which forms, together with the actuating cylinder bore, an edge via which the at least one channel is opened.

2. The actuating cylinder according to claim 1, wherein the stop bore is inclined obliquely with respect to the actuating cylinder bore.

3. The actuating cylinder according to claim 1, wherein the stop bore and the actuating cylinder bore are formed by machining.

4. The actuating cylinder according to claim 1, wherein: the actuating piston is a hollow piston having an interior which defines a part of the actuating pressure chamber, and the at least one channel is defined in the actuating piston.

5. The actuating cylinder according to claim 1, wherein the hydraulic stop has a circumferential groove formed on an outer circumference of the actuating piston and into which the at least one channel opens.

6. An axial piston machine comprising: an actuating cylinder comprising: an actuating cylinder bore defined in a main component; and an actuating piston movably guided in the actuating cylinder bore, the actuating piston defining an actuating pressure chamber, the actuating piston having a hydraulic stop for the actuating piston at which the actuating pressure chamber is connected via at least one channel to a surrounding area of the actuating cylinder, the hydraulic stop including a stop bore defined in the main component and which forms, together with the actuating cylinder bore, an edge via which the at least one channel is opened; a swash plate to which the actuating piston is coupled; and a housing in or on which the stop bore and the actuating cylinder bore are formed, the housing forming the main component of the actuating cylinder.

7. The axial piston machine according to claim 6, wherein the stop bore is a through-bore which penetrates through the housing.

8. The axial piston machine according to claim 7, wherein the through-bore is a leakage bore, and wherein a surrounding area of the actuating cylinder is an interior of the housing, and the leakage bore is configured to connect the interior of the housing to an outside of the axial piston machine.

9. The axial piston machine according to claim 6, wherein the stop bore is configured to be closed with one of a stopper and a closure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Several exemplary embodiments of an axial piston machine according to the disclosure are represented in the figures.

[0021] In the figures:

[0022] FIG. 1 shows, in a longitudinal section, the axial piston machine according to the disclosure according to a first exemplary embodiment while omitting a closure screw,

[0023] FIG. 2 shows an enlarged cut-out of the axial piston machine according to the disclosure according to a second exemplary embodiment with actuating piston and closure screw, and

[0024] FIG. 3 shows the cut-out from FIG. 2 while omitting the actuating piston and the closure screw.

DETAILED DESCRIPTION

[0025] FIG. 1 shows an axial section through an axial piston machine 1 of swash plate design. A shaft 3 is rotatably mounted on a first bearing 4 and a second bearing 5 in a housing 6 of axial piston machine 1. Housing 6 is divided into a base body 6a and a cover body 6b screwed to base body 6a. A cylinder drum 7 is connected to shaft 3 in a rotationally conjoint manner. Cylinder bores 8 arranged on a partial circle are located therein, in which cylinder bores 8 pistons 9 are axially displaceable. Pistons 9 are connected via ball joints 10 to respective sliding blocks 11 and are supported via sliding blocks 11 on a swash plate 12 formed as a pivot cradle.

[0026] The connection of cylinder bores 8 to a high-pressure line and to a low-pressure line (both not shown) is carried out via a control body 13 which has a kidney-shaped high-pressure opening 14 and a likewise kidney-shaped low-pressure opening 15.

[0027] Cylinder drum 7 is held bearing against control body 13 by means of a spring 22. To this end, spring 22 is supported via a first ring on cylinder drum 7 and via a second ring 24 on shaft 3. Cylinder drum 7 can be moved axially with respect to shaft 3 via a key-and-slot connection.

[0028] The stroke of pistons 9 in cylinder bores 8 is defined by a pivot angle of swash plate 12. Swash plate 12 is represented in FIG. 1 in its neutral position and twice in a position pivoted by pivot angle .

[0029] An adjusting device 2 serves to pivot swash plate 12. It is largely integrated into a receiving bore or cylinder bore 16 of housing 6 and is composed of an actuating piston 18 which is connected via a ball joint connection 17 to swash plate 12 and is guided axially in cylinder bore 16 and a control valve 19 inserted into cylinder bore 16 and an actuating member 21 which defines a control force for a valve piston 20 of control valve 19. Control valve 19 and actuating piston 18 are arranged axially offset to one another in cylinder bore 16.

[0030] Actuating cylinder bore 16 has a longitudinal axis 26 which is inclined at an angle <45 to a shaft longitudinal axis 28. A leakage bore 30 is provided in base body 6a of housing 6, which leakage bore 30 penetrates through a wall of base body 6a. A bore axis 32 of leakage bore 30 is preferably arranged perpendicular to shaft longitudinal axis 28 and, however, runs preferably spaced apart from shaft longitudinal axis 28.

[0031] In particular, however, bore longitudinal axis 32 intersects with longitudinal axis 26 of actuating cylinder bore 16 at an angle between 45 and 135. According to the disclosure, leakage bore 30 is positioned along longitudinal axis 26 of actuating cylinder bore 16 such that it forms a hydraulic stop for actuating piston 18 in the extended position (also shown in FIG. 1), in which position pivot angle is minimal. Leakage bore 30 is thus also used according to the disclosure as what is known as stop bore 30. If, during operation of the axial piston machine according to the disclosure, a circumferential groove 34 formed on the outer circumference of actuating piston 18 reaches the edge (bottom left in FIG. 1) of stop bore 30, an interior of actuating piston 18, which is connected directly to an actuating pressure chamber 36 or even largely forms it, is relieved of pressure toward an interior 38 of housing 6. A further extension movement of the actuating piston is thus prevented independently of the supplied actuating pressure medium.

[0032] FIG. 2 shows the cut-out of the axial piston machine according to the disclosure with the hydraulic stop according to a second exemplary embodiment. The exemplary embodiment only has slight changes in comparison with the first exemplary embodiment according to FIG. 1 and is a mirror-image of the representation from FIG. 1.

[0033] When pivoting back the pivot cradle (not shown), actuating piston 18 moves (to the left in FIG. 2) and is shown in FIG. 2 in a position immediately before the response of the hydraulic stop. The interior of actuating piston 18 and actuating pressure chamber 36 are acted upon with actuating pressure medium which escapes into interior 38 of housing 6 upon response of the hydraulic stop. This occurs on a flow path through one or more channels 40 formed as radial bores and via circumferential groove 34 and via stop bore 30 which is simultaneously used as leakage bore 30. In this case, an edge 42 serves as a control edge which is only apparent in FIG. 2 as a corner and which is only formed by the introduction of the two intersecting bores 16, 30.

[0034] The production outlay of this hydraulic stop is in particular very small if a leakage bore 30 provided in any event is only positioned such that it forms edge 42 together with actuating cylinder bore 16 at a predetermined point. After the production of stop bore 30 by machining, a thread is also provided therein so that a closure formed as a closure screw can be inserted there in a sealing manner.

[0035] FIG. 3 shows the hydraulic stop of the axial piston machine according to FIG. 2, wherein closure screw 44 and actuating piston 18 were omitted. It is clearly apparent that actuating cylinder bore 16 and stop or leakage bore 30 are introduced at an angle <90 to one another into housing 6 or base body 6a. Here, the two bores 16, 30 form arcuate edge 42 which serves as a control edge, of which only the half lying below the drawing plane is apparent in FIG. 3.

[0036] An actuating cylinder for an adjusting apparatus of a pivot angle of a hydrostatic axial piston machine is disclosed. The actuating cylinder has a hydraulic stop which connects an actuating pressure chamber of the actuating cylinder to an interior of the housing of the axial piston machine if the actuating piston is maximally extended. To this end, a channel is provided on the actuating piston side, while a control edge is provided on the housing side. The control edge is formed at the interface of a stop bore with the actuating cylinder bore. It is particularly preferred if the stop bore is also a leakage bore of the axial piston machine.

LIST OF REFERENCE NUMBERS

[0037] 1 Axial piston machine [0038] 2 Adjusting device [0039] 3 Shaft [0040] 4 Bearing [0041] 5 Bearing [0042] 6 Housing [0043] 6a Base body [0044] 6b Cover body [0045] 7 Cylinder drum [0046] 8 Cylinder bore [0047] 9 Piston [0048] 10 Ball joint [0049] 11 Sliding block [0050] 12 Swash plate [0051] 13 Control body [0052] 14 High-pressure opening [0053] 15 Low-pressure opening [0054] 16 Actuating cylinder bore [0055] 17 Ball joint connection [0056] 18 Actuating piston [0057] 19 Control valve [0058] 20 Valve piston [0059] 21 Actuating member [0060] 22 Spring [0061] 23 Ring [0062] 24 Ring [0063] 26 Longitudinal axis [0064] 28 Shaft longitudinal axis [0065] 30 Leakage bore/stop bore [0066] 32 Bore longitudinal axis [0067] 34 Circumferential groove [0068] 36 Actuating pressure chamber [0069] 38 Interior [0070] 40 Channel [0071] 42 Edge [0072] 44 Closure [0073] Pivot angle