CN106481526B

CN106481526B - Hydrostatic axial piston machine

Info

Publication number: CN106481526B
Application number: CN201610720719.1A
Authority: CN
Inventors: S.豪格; F.诺特; J.勒姆; R.舍雷尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-08-26
Filing date: 2016-08-25
Publication date: 2020-07-17
Anticipated expiration: 2036-08-25
Also published as: DE102016214425A1; US20170058877A1; DE102016214422A1; CN106481526A

Abstract

Disclosed is a hydrostatic axial piston machine having an adjustable displacement volume and a cylinder in which a plurality of working pistons are accommodated in an axially movable manner, which working pistons are supported on sliding surfaces of a rocker which is mounted in a pivotable manner on a sliding bearing fixed to a housing for adjusting the displacement volume, wherein at least one hydrostatic first relief pressure region can be formed between the sliding bearing and the rocker.

Description

Hydrostatic axial piston machine

Technical Field

The invention relates to a hydrostatic axial piston machine according to the invention.

Background

An axial piston machine of the generic type is shown, for example, in DE 102012022999 Al. The axial piston machine is equipped with an adjustable displacement volume in a swash plate design and has a cylinder barrel connected to the drive shaft in a rotationally fixed manner, in which cylinder barrel a plurality of cylinder bores are formed approximately parallel to the axis of rotation of the drive shaft. In the cylinder bores, in each case one working piston is accommodated so as to be axially movable. The working piston is supported on a slide surface of a rocker, which is mounted so as to be pivotable on a slide bearing fixed to the housing for adjusting the displacement volume.

In order to improve the sliding of the rocking cradle on the slide bearing and to relieve the friction surfaces, a hydrostatic relief pressure region is provided, which can be formed in a relief pressure packet provided for this purpose on the rocking cradle side or on the slide bearing side. In this case, several of the relief pressure packs are connected via pressure medium channels to the high-pressure side or high-pressure connection of the axial piston machine, while the other relief pressure packs are connected via pressure medium channels through the pivot cradle to the pressure chambers of the secondary cylinders or of the control cylinders of the control system of the axial piston machine.

A disadvantage of this solution is that the pressure medium connection of the relief pressure packet to its pressure medium source is continuous, so that a continuous leakage flow through the relief pressure region and thus pressure medium and energy losses reduce the efficiency of the axial piston machine.

Disclosure of Invention

Accordingly, the object of the present invention is to create an axial piston machine with correspondingly improved or increased efficiency and improved stability of the drive.

This object is achieved by a hydrostatic axial piston machine having the features of the invention.

Advantageous modifications of the axial piston machine are described in the preferred and other embodiments.

Hydrostatic axial piston machines are designed in a swash plate design and have an adjustable displacement volume. The axial piston machine has a cylinder, which is connected in a rotationally fixed manner to a drive shaft and in which a plurality of working pistons are accommodated in an axially movable manner. The last-mentioned is in particular accommodated in a cylinder bore which is configured approximately parallel to the axis of rotation of the drive shaft. The working piston is mounted indirectly or directly on a slide surface of a rocker of the axial piston machine, which rocker is mounted so as to be pivotable for adjusting the displacement volume on a slide bearing fixed to the housing, in particular on two symmetrically arranged slide bearings, in particular bearing housings. In this case, at least one hydrostatic first relief pressure region can be formed or formed between the plain bearing and the rocking cradle. According to the invention, an adjustable first flow cross section is provided in a first pressure medium flow path from a first pressure medium source of the axial piston machine directly to the hydrostatic first relief pressure region.

The axial piston machine can thus be prepared for: hydrostatic relief is provided as required (for example for an operating phase or operating point). As a result, leakage losses from the relief pressure region to the outside can be reduced, which in principle reduces the operating costs of the axial piston machine and increases the efficiency in terms of the volume of the axial piston machine. In principle, the hydrostatic relief leads to a more precise adjustment of the displacement volume, since in particular at the beginning of the adjustment process less static friction has to be overcome. Furthermore, the swing dynamics of the regulation can be optimized and the control or regulation of the regulation proves to be more stable. The stability of the drive can be increased by increased friction when not being swung.

In a further development of the axial piston machine, a hydrostatic second relief pressure region can be formed between the plain bearing and the rocking cradle (in particular for and during the adjustment and/or adjustment back of the displacement volume). In this case, an adjustable second flow cross section is provided in the second pressure medium flow path from the second pressure medium source directly to the hydrostatic second relief pressure zone. The hydrostatic relief stability of the rocking cradle is improved by providing two or more relief pressure zones which are thereby independently of each other capable of being supplied with pressure medium.

In a further embodiment, the axial piston machine has an adjusting device which has a hydraulic adjusting cylinder for adjusting the displacement volume. The first pressure medium source can be designed, in particular designed, via a control pressure chamber of the control cylinder.

In one variant, the first adjustable flow cross section is formed in the adjusting piston.

In a further development of the axial piston machine, the adjusting device for the return displacement volume has a hydraulic return cylinder, wherein the second pressure medium source can be formed, in particular formed, by a return pressure chamber of the return cylinder.

In a further embodiment, the adjustable second flow cross section is formed in the adjusting piston.

In a further embodiment, the first relief pressure region can be acted upon with pressure medium via the displacement of the control piston into the control cylinder and via the reduction of the control pressure chamber. In this way, pressure medium which is relieved to low pressure can additionally be used in the first relief pressure region of the hydrostatic pressure, so that pressure medium energy is saved.

In a further embodiment, the second relief pressure region can be acted upon with pressure medium via the movement of the return piston into the return cylinder and via the reduction of the return pressure chamber.

In an alternative variant, the first pressure medium source is a partial quantity of the working pressure chamber in the cylinder tube which is limited by the working piston. In particular, the partial quantity is formed by a working chamber which is in pressure medium connection with a high-pressure chamber or a high-pressure connection of the axial piston machine, which is fastened to the housing.

In one variant, the flow cross section can be adjusted via two parts or assemblies of the axial piston machine which move relative to one another as the displacement volume changes, depending on the pivot angle. In this way, for adjusting the throughflow cross section, no separate device is provided, but the part of the axial piston machine which is provided in any case and which moves during the adjustment or the setting back is used. In this way, the control-technical and installation-technical outlay is reduced.

In a further embodiment, the adjustment of the flow cross section is coupled to a change (i.e. an adjustment and/or a return) of the outlet volume, in particular of the pivot angle of the pivot cradle. In this case, the coupling can be such that the flow cross section likewise increases with increasing displacement volume or pivot angle. As an alternative, an inverted coupling can also be considered.

In a further embodiment, starting from the respective pressure chamber (working pressure chamber or control pressure chamber or return pressure chamber), the pressure medium flow path passes straight to the respective relief pressure region: a piston (working piston or adjusting back piston) assigned to the pressure medium flow path, a slide shoe of the piston, and a pendulum cradle. In this way, the pressure medium flow path is short and does not have to be guided past, for example, a shell wall. Since the pressure medium flow path is short, small pressure losses are possible.

As already mentioned, the adjustable flow cross section can be formed by a part of the axial piston machine. In a variant, the flow cross section is thus defined by the rocking cradle and the slide bearing, for example. When the displacement volume is set, the pivoting cradle pivots towards the slide bearing, so that the corresponding flow cross section is changed.

Alternatively or additionally, the adjustable flow cross section can be produced, for example, by a component pair: a rocking cradle/working piston or rocking cradle/slipper or working piston/slipper definition. During the adjustment or the adjustment back, the components of all the mentioned pairs are subjected to a relative movement with respect to one another, which can be utilized to adjust the respective flow cross section.

In a further embodiment, the adjustable flow cross section is formed by an adjustable, in particular individually controllable, throttle device. In this variant, a possibility is thus provided for adjusting the throughflow cross section, which is able to be controlled independently of the mentioned part of the axial piston machine which moves during the adjustment or the setting back. In this way, the pressure medium loading of the relief pressure zone or zones can also be made more flexible.

Of course, mixed forms are also possible, for example when the adjustable first flow cross section is formed by one of the component pairs mentioned and the adjustable second flow cross section is formed by an adjustable throttle device or vice versa.

In a variant, the adjustable throttle device is formed by an independently controllable valve or a controllable diaphragm.

In order to build up the relief pressure zone or zones particularly quickly and in this way to keep the static friction between the rocking cradle and the slide bearing and the resulting actuating torque low, the valve is designed as a quick-acting valve (electromagnetically or piezoelectrically actuated) in a further development. In this case, the switching time thereof is in particular smaller or significantly smaller than the switching time of a valve of the axial piston machine, via which a control device, in particular a control cylinder and/or a return cylinder, can be supplied with pressure medium. In this way, it is ensured that the one or more relief pressure zones are built up significantly faster than the actuation of the pivoting cradle for adjusting or adjusting the displacement volume.

In a further embodiment, the respective relief pressure region is limited by at least one plain bearing-side relief pressure packet which is formed in the bearing surface of the plain bearing. Alternatively or additionally, the respective relief pressure region is limited by at least one relief pressure packet on the pendulum cradle side, which is formed in the bearing surface of the pendulum cradle facing the plain bearing. A corresponding relief pressure package can be formed, for example, via a flat, pot-shaped recess or a flat, closed groove.

In a further embodiment, the slide bearing-side relief pressure package overlaps the swing rocker-side relief pressure package at least in sections. In this way, the size of the relief pressure area formed by these relief pressure packs changes as the rocking cradle rocks. Thereby, the relief force of the relief pressure area becomes larger and/or smaller depending on the swing angle.

In a further development of the axial piston machine, the rocking cradle has a neutral point in which the displacement volume is zero. In the neutral point, the slide bearing-side relief pressure package and the swing rocker-side relief pressure package overlap at least in sections. The overlap is preferably designed such that the relief pressure region increases in its size with increasing pivot angle and displacement volume. Then, as the discharge volume increases, the relief force also increases.

In a variant, the bearing surface of the rocking cradle extends substantially symmetrically to the neutral plane of the rocking cradle. In contrast, the swing-cradle-side relief pressure packet extends asymmetrically with respect to the mentioned neutral plane. By this asymmetry, the relief pressure area resulting therefrom can be prepared for a preferred range of oscillation angles of the axial piston machine.

In a further embodiment, the pendulum cradle has a plurality of pendulum-cradle-side relief pressure packets arranged at a distance from one another in the direction of oscillation. Alternatively or additionally, the plain bearing has a plurality of plain bearing-side relief pressure packets arranged at a distance from one another in the direction of oscillation. Through these multiple relief pressure packages, the relief pressure zone derived from the relief pressure package can extend over a large angular range.

In one embodiment, the relief pressure package can be supplied with pressure medium via in each case one adjustable flow cross section, in particular via in each case one adjustable throttle device, or via a common adjustable flow cross section, in particular via a common throttle device. In the first case, the relief pressure region is configured to be flexibly adapted to the pivot angle or the load situation, respectively, as required. So that, for example, a single one or more of the relief pressure packages can be adjusted to or from. The second case represents a simpler, somewhat less flexible solution in terms of device technology.

In a further embodiment, the axial piston machine has a control device, via which at least the adjustment or the adjustment and the adjustment back of the pivot cradle can be controlled.

In a further development, the at least one throttle device can also be controlled by the control device, in particular as a function of the pivot angle.

In a further development of the axial piston machine, the control device is designed in such a way that, by means of the control device, a necessary change in the displacement volume can be estimated from the operating profile of the axial piston machine, in particular from the profile of one or more operating parameters. In a further embodiment, at least one throughflow cross section of the one or more throttle devices which is adapted thereto can then be controlled, in particular adjusted, and enlarged by the control device.

In the drawings, embodiments of a hydrostatic axial piston machine according to the invention are shown. The invention will now be explained in detail on the basis of these figures.

Drawings

The figure is as follows:

figure 1 shows a longitudinal section through a hydrostatic axial piston machine according to a first exemplary embodiment in a longitudinal section,

figures 2 and 2a show the hydraulic circuit diagram of the hydrostatic axial piston machine according to figure 1,

fig. 3 shows in a schematic representation the pressure medium source, the adjustable flow cross section and the relief pressure region of the axial piston machine according to fig. 1 and 2.

Figure 4 shows in a schematic representation a rocking cradle of a hydrostatic axial piston machine according to a second embodiment,

figure 5 shows in a schematic representation a rocking cradle of a hydrostatic axial piston machine according to a third embodiment,

figure 6 shows the working piston of the shoe of an axial piston machine with hydrostatic forces according to a fourth embodiment,

figure 7 shows the working piston of the shoe of an axial piston machine with hydrostatic forces according to a fifth embodiment,

figure 8 shows in a schematic representation a sliding bearing according to a sixth embodiment, a rocking cradle and a working piston of a slipper of an axial piston machine with hydrostatic forces,

figure 9 shows in schematic representation a rocking cradle of a hydrostatic axial piston machine according to a seventh embodiment,

figure 10 shows in a schematic representation a rocking cradle of a hydrostatic axial piston machine according to figures 1 and 2,

figure 11 shows in schematic representation a rocking cradle of a hydrostatic axial piston machine according to an eighth embodiment,

fig. 12 and 13 show in a schematic illustration two embodiments of a swing cradle side relief pressure package in a coiled illustration.

Detailed Description

Fig. 1 shows a hydrostatic axial piston machine 1 in longitudinal section, which is designed in the illustrated exemplary embodiment as a hydraulic pump and thus has a firmly associated high-pressure port HD and a firmly associated low-pressure port ND, which are designed at a housing cover 2 and are not shown in fig. 1, a drive shaft 4 drives in rotation about a rotational axis 3 and carries a cylinder barrel 6, in which a plurality of cylinder bores 8 are provided, distributed over the circumference, in which respective working pistons 10 are guided in the axial direction, the working pistons 10 are each supported in a sliding manner via shoes 11 on sliding surfaces 12 of a rocking cradle 13, the last-mentioned rocking cradle does not rotate, but can be adjusted in its inclination via an adjusting cylinder 14 of an adjusting device, in this way the rocking angle α and thus the displacement volume of the axial piston machine 1 can be adjusted at a minimum rocking angle α_minAnd a maximum swing angle α_maxAt a minimum swing angle α_minThe swash plate 12 is arranged perpendicular to the axis of rotation 3 so that during the revolution of the cylinder barrel 6 and the working piston 10 no stroke movement occurs and the displacement volume or transfer volume Vg of the axial piston machine 1 is zero at the maximum pivot angle α_maxThe slide surface 12 is set up maximally towards the axis of rotation 3, so that a maximum transfer volume Vg is obtained during the revolution of the cylinder 6 and the working piston 10_max。

Swinging rockerThe shelf 13 being at a maximum swing angle α in a straight direction_maxIs prestressed against the adjusting force of the adjusting cylinder 14 via a spring 18 of the adjusting cylinder 23, which is supported on a bushing 16 inserted into the housing cover 2, the adjusting cylinder 14 is arranged relative to the adjusting cylinder 23 with reference to the axis of rotation 3, the pendulum cradle 13 is swiveled back to a minimum swivel angle α when the adjusting pressure chamber 15 of the adjusting cylinder 14 is supplied with adjusting pressure medium_minThis movement is limited to a swing angle α by a stop 20 (which is disposed within the interior of bushing 16)_min=0 °. The control pressure chamber 15 is bounded on the one hand by a bushing 17 screwed into the housing cover 2 and on the other hand by a control piston 26 covering said bushing 17. The bottom of the adjusting piston 26 is supported via a slide shoe at an articulation point (with a spherical head) which is mounted in the pivot cradle 13 and is spaced laterally from the pivot axis. The set back pressure chamber 24 is defined by the bushing 16, the stop 20 and the set back piston 22 embedded in the bushing 16. The adjusting piston 22 is coupled to the pivot cradle 13 via a sliding shoe and a pivot point (with a ball head) spaced from the pivot axis.

The rocking cradle 13 has two cylindrical bearing segments 28 parallel to the rocking axis and symmetrical to the sectional plane shown in fig. 1, which are each pivotably received in a slide bearing 30 embedded in a bearing block. In fig. 1, the bearing segment 28 arranged behind the sectional plane and the associated slide bearing 30 are shown in dashed lines, since they are covered by the pivoting cradle 13. Axially distributed along the direction of oscillation, a plurality of relief pressure packs 232 are inserted into the plain bearing 30, which can be supplied with pressure medium via a pressure medium source of the axial piston machine 1. In this way, a relief pressure region between the slide bearing 30 and the rocking cradle 13, in particular its bearing segment 28, can be built up.

Before discussing the embodiment of the pressure medium loading according to this relief pressure zone of fig. 2 and 2a, it should be shown that in principle possible solutions of the pressure medium supply of the relief pressure package and its construction solution are suggested.

The following illustrations of fig. 3 to 13 are very schematic.

Fig. 3 shows the principle according to which one or more relief pressure packs 32 are supplied with pressure medium in order to build up a relief pressure zone between the bearing segment 28 of the rocking cradle 13 and the slide bearing 30. For this purpose, a pressure medium source 36 is provided, which is in pressure medium connection with the relief pressure packet 32 via the pressure medium flow path 34. The pressure medium connection is controlled via an adjustable flow cross section (in particular of the throttle device) arranged in the pressure medium flow path 34. The flow cross section can be formed, for example, by parts which are moved relative to one another during pivoting of the pivoting cradle, for example, the pivoting cradle and the slide bearing. Alternatively, the flow cross section can be formed by a separately controllable throttle device, for example a valve.

According to fig. 4, the pressure medium supply of the swing-cradle-side relief pressure packet 32 (which is inserted into the sliding surface of the bearing segment 28) takes place via the working chamber 9 of the axial piston machine 1, which is charged with high pressure. A working piston 10 is shown, which is supported at a slide surface 12 in the rocking cradle. The working piston is in this case supported directly at the sliding surface 12 and is suitably sealed at this sliding surface, so that leakage in the contact region of the working piston 10/rocking cradle 13 is minimal. The relief pressure package 32 is connected to the working chamber 9 via a pressure medium flow path 34 which runs through the rocking cradle 13. Here, the pressure medium flow path 34 also passes through the working piston 10. In this case, the adjustable flow cross section in the pressure medium flow path 34 is designed as an individually controllable throttle device 38. The relief pressure package 32 is configured asymmetrically with respect to the neutral plane 40 of the rocking cradle. In this case, a larger section of the relief pressure packet 32 extends counter to the pivoting direction for increasing the discharge volume. The smaller section extends in the mentioned direction.

Fig. 5 shows a further exemplary embodiment, in which a separately actuatable throttle device in the working piston 10 is omitted and instead an adjustable flow cross section at the bearing point of the working piston 10 at the slide surface 12 is provided. Due to the relative movement of the pendulum cradle 13 with respect to the working piston 10 supported thereon, an adjustment of the flow cross section is simultaneously achieved, which is defined by the working piston-side and pendulum cradle-side mouths of the pressure medium flow path. In order to be able to cover the range of the pivot angle of the pivot cradle, the mouth of the pressure medium flow path 34 in the slide surface 12 is configured to be slightly larger, so that the movement of the mouth of the working piston 10, which occurs during pivoting, toward the mouth in the slide surface 12 can be covered.

Fig. 6 shows a further exemplary embodiment in which the adjustable flow cross section 38 is formed by the geometric features of the slipper 11 and of the working piston 10. In this case, the pressure medium flow path 34 passes through the working piston 10 and the slipper 11. The first section 34a merges at the end into the spherical head of the working piston 10, and the second section 34b passes from its side which is in contact with the sliding surface through the sliding shoe 11 toward the spherical recess, in which the spherical head is accommodated.

Fig. 7 shows in principle the control principle, in which an adjustable flow cross section is arranged as an adjustable throttle device 38 in the working piston 10, as already discussed in fig. 4. The slipper 11 is also shown at this time.

Fig. 8 shows an embodiment in which the inflow of pressure medium into the rocking cradle 13 via the working piston 10 with the slipper 11 takes place. The adjustable flow cross section 38 is located between the skid shoe 11 and the pivot cradle 13.

Fig. 9 shows an embodiment in which a slide bearing-side relief pressure package 232 is provided in addition to the swing cradle-side relief pressure package 32, in the neutral position the two relief pressure packages 32, 232 have an overlap, if the swing cradle is then oriented in the direction of increasing the displacement volume, i.e. in the direction of α⁺The directional swing increases the relief pressure area formed by the two relief pressure packs 32, 232, in response to which the rocking cradle is more hydrostatically relieved with an increased swing angle α.

FIG. 10 shows another embodiment with multiple oscillation directionsα⁺Slide bearing-side relief pressure packs 232 arranged at a distance from one another, which are fluidically connected to the pressure medium source 36 via the pressure medium flow path 34. Here, each relief pressure package 232 is connected via a parallel branch of the pressure medium flow path 34. The relief pressure packets 232 thus supplied in parallel with pressure medium can be supplied with pressure medium via a common throttle device 38, which is designed as a separate controllable valve.

As an alternative to this, the pressure medium supply of the relief pressure packet 232 can be configured according to fig. 11, each parallel branch of the pressure medium flow path 34 having its own throttle device 38, which can each be actuated independently, it is also conceivable to provide it with fewer throttle devices 38 than the relief pressure packets 232, i.e. to provide one throttle device for a plurality of relief pressure packets, in this way, depending on the pivot angle, the individual relief pressure packets 232 can be supplied with pressure medium or locked from the pressure medium supply of the pressure medium source 36, in this way, each individual relief pressure packet 232 of the relief pressure packets 232 with different throttle cross sections of the respective throttle device 38 can be supplied with pressure medium, in this way, the resulting relief pressure region can be matched to the pivot angle α, and in this way, the forces generated locally in the plain bearing 30 can be matched very well.

Fig. 12 and 13 show in a schematic illustration a swing cradle side relief pressure package 32. The dependent mouths of the relief pressure package 32 and the pressure medium flow path 34 supplying the relief pressure package are shown separately.

The relief pressure package 32 is symmetrically arranged with respect to the neutral plane 40. According to fig. 12, two relief pressure packs 32 are arranged on both sides of the neutral plane 40 at each bearing segment 28 of the rocking cradle 13. The mouths of the pressure medium flow paths 34 into the respective relief pressure packet 32 are arranged diagonally to one another in the corners of the relief pressure packet 32, which is of rectangular design in principle. The relief pressure packet 32 according to fig. 12 is supplied with pressure medium via the return pressure chamber 24 and the regulating pressure chamber 15 of the hydraulic pump according to fig. 1. Here, the relief pressure packet 32 indicated at a is used for being loaded with pressure medium via the return pressure chamber 24 and the relief pressure packet 32 indicated at B is used for being loaded with pressure medium via the regulating pressure chamber 15.

In contrast to the exemplary embodiment according to fig. 12, fig. 13 shows a relief pressure packet 32 which extends symmetrically to a neutral plane 40 across the latter. Also here, the relief pressure package indicated with a 32 is supplied from the return pressure chamber 24 with pressure medium and the relief pressure package indicated with B is supplied from the regulating pressure chamber 15 with pressure medium. In contrast to the relief pressure package according to fig. 12, the relief pressure package according to fig. 13 is constructed more narrowly, but with the same base surface.

Fig. 2 shows a hydraulic circuit diagram of the axial piston machine 1 for showing the pressure medium supply of the relief pressure packet 232 according to fig. 10, which is located at this pressure medium supply, which is reduced compared to fig. 2a, for the sake of simplicity of fig. 2, the axial piston machine 1 has a high-pressure line 42 and a low-pressure line 44, wherein the axial piston machine transfers pressure medium from the low-pressure line 44 directly to the high-pressure line 42 during pump operation, fig. 2 shows the control cylinder 14 acting on the pivoting cradle 13 and the return cylinder 23 also acting on the pivoting cradle 13, the axial piston machine 1 has an electromagnetically actuatable 3/3 proportional directional valve 46, which, when the associated electromagnet a is energized, connects the high-pressure line 42 to the control pressure chamber 15, when the end position 46b of the valve 46 is energized, connects the control pressure chamber 15 to the tank T, when the electromagnet b of the valve 46 is energized, the control pressure chamber 15 is connected to the tank T, and the control piston 46 is moved out of the second end 6332, thereby increasing the control piston angle α.

The return pressure chamber 24 of the return cylinder 23 can be connected to the high-pressure line 42 via the direction control valve 52 2/2 into a pressure medium connection. The last-mentioned 2/2 directional control valve is biased into the closed position by a spring and can be adjusted into the feed-through position by electromagnetic actuation, so that the pressure medium connection mentioned can be opened.

Via an adjustable throttle device 38 (which can be actuated electromagnetically) designed as an 2/2 directional control valve, the control pressure chamber 15 and the relief pressure packet 232 arranged on the plain bearing side can be brought into pressure medium connection, as shown in fig. 2 and 2 a. Fig. 2 shows an optional adjustable throttle device (38, dashed line) via which the return pressure chamber 24 can enter the pressure medium connection with an optional swing-cradle-side relief pressure package (32, dashed line).

For the purpose of controlling the displacement volume and the relief pressure region of the axial piston machine 1, it is also provided with a control unit ECU for the purpose of explaining the pressure medium supply of the relief pressure package 232 that the axial piston machine 1 is operated in a stable state with a fixed pivot angle α, in response to which no adjustment of the pivot angle is carried out at all, at this point in time the 2/2 directional control valve 52 is actuated electromagnetically so that the return pressure chamber 24 is supplied with the high pressure in the high-pressure line 42, the 3/3 proportional directional valve 46 is adjusted via the control unit ECU and the energization of the electromagnet a in the direction of the end point 46a so that the high-pressure line 42 is in throttled pressure medium connection with the relief pressure chamber 15, the high pressure of the spring 18 acting at the return piston 22 and the pressure in the relief pressure chamber 15 acting at the control piston 26, the force acting on the pivot cradle 13 maintaining the pivot cradle 13 in a balanced, i.e. at a constant pivot angle α, since the pivot cradle 13 is not adjusted at present, the throttle pressure is not present, the throttle pressure of the throttle pressure package 38 can be adjusted so that the pressure package 38 is also acted upon by the pressure package to prevent leakage.

In order to provide the above-mentioned time gap between the buildup of the relief pressure region and the regulation, the throttle device 38 can be designed, for example, as a quick switching valve with a significantly smaller switching time than the proportional directional valve 3/3, for example, as a pressure medium feed back into the control pressure chamber 15, until the new hydrostatic force balance is set at the rocker 13 and the regulation is terminated, the pressure medium feed back into the control pressure chamber 15 is carried out, the pressure medium feed back into the control pressure chamber 26 is carried out until the new pressure medium feed back into the control pressure chamber 15 is reversed, and the pressure medium leakage from the relief pressure chamber 38 is blocked again, so that the pressure medium feed back into the relief pressure chamber 232 is prevented and the pressure medium leakage from the relief pressure chamber 232 is prevented.

When the pivot angle α increases, the control of the pressure medium supply is effected in such a way that firstly, before the adjustment, the electromagnet of the throttle device 38 is energized again, so that a pressure medium connection of the adjustment pressure chamber 15 with the relief pressure packet 232 is established and a relief pressure zone can be built up, then, via the energization disconnection of the two electromagnets a and b of the 3/3 proportional directional valve 46 by the control device ECU, an adjustment of this valve 46 into the spring-centered central latching point 46c is effected (in which the adjustment pressure chamber 15 is disconnected from the high-pressure line 42) and at the same time via the bypass line 48 and the partition 50 arranged therein into a throttled pressure medium connection with the tank T is effected, correspondingly, when the adjustment piston 26 is moved in, the pressure medium is guided straight from the adjustment pressure chamber 15 to the tank T, and at the same time a sufficiently high pressure for the construction of the relief pressure zone remains in the adjustment pressure chamber 15, the swing cradle 13 is thus constantly subjected to a greater pivot angle until the adjustment of α, and the pressure medium connection of the relief pressure chamber 15 is then blocked, so that the pressure medium connection of the relief pressure packet 38 is interrupted.

Hydrostatic axial piston machines in the form of swash plates are disclosed, for which hydrostatic relief pressure zones can be formed between the rocking cradle and the plain bearings. In this case, an adjustable flow cross section is provided for relieving the pressure region of the required pressure medium supply. The flow cross section can vary in its cross section, in particular as a function of the setting or setting back of the outlet volume.

Reference sheet

1-body static axial piston machine

2 cover

3 axis of rotation

4 drive shaft

6 cylinder barrel

8 cylinder hole

9 working pressure chamber

10 working piston

11 sliding boots

12 sliding surface

13 swing cradle

14 adjusting cylinder

15 regulated pressure chamber

16. 17 liner

18 spring

20 stop part

22-adjusting piston

23 adjusting cylinder

24 pressure regulating chamber

26-section piston

28 bearing segment

30 dynamic bearing

32, a first step of removing the first layer; 232 deloading pressure bag

34 force medium flow path

36 force medium source

38 flow device

39 bearing surface

Plane of 40 sexuality

42-line circuit

44 low voltage line

463/3 proportional direction valve

46a, 46a end position

46c cut-off position

48 bypass line

50 baffle

ECU control apparatus

α dynamic angle

α_minSmall angle of oscillation

α_maxLarge angle of oscillation

Vg out volume

Vg_maxA large transfer volume.

Claims

1. Hydrostatic axial piston machine with an adjustable discharge volume and a cylinder (6) in which a plurality of working pistons (10) are accommodated in an axially movable manner, which working pistons are supported on a slide face (12) of a rocking cradle (13) which is mounted in a pivotable manner on a slide bearing (30) fixed to the housing for adjusting the discharge volume (Vg), wherein at least one hydrostatic first relief pressure region (32, 232) can be formed between the slide bearing (30) and the rocking cradle (13), characterized in that an adjustable first throughflow cross section (38) is provided in a first pressure medium flow path (34) from a first pressure medium source (36, 15) directly to the hydrostatic first relief pressure region (32, 232), wherein the adjustable first throughflow cross section (38) is delimited by the rocking cradle (13) and the working pistons (10), or wherein the first adjustable flow cross section (38) is delimited by the pivoting cradle (13) and the sliding shoe (11) of the working piston (10), or wherein the first adjustable flow cross section (38) is delimited by the working piston (10) and the sliding shoe (11) of the working piston (10).

2. An axial piston machine according to claim 1, wherein a hydrostatic second relief pressure zone can be formed between the plain bearing and the rocking cradle, and an adjustable second flow cross section is provided in the second pressure medium flow path from the second pressure medium source directly to the hydrostatic second relief pressure zone.

3. Axial piston machine according to claim 2, with a regulating device (14, 23) which has a hydraulic regulating cylinder (14) for regulating the displacement volume (Vg), wherein the first pressure medium source (36) can be formed via a regulating pressure chamber (15) of the regulating cylinder (14).

4. An axial piston machine according to claim 3, wherein the adjusting device (14, 23) has a hydraulic return cylinder (23) for returning the displacement volume (Vg) and the second pressure medium source can be formed via a return pressure chamber of the return cylinder.

5. An axial piston machine according to any one of claims 1 to 4, wherein the first pressure medium source (36) is in connection with a partial quantity of pressure medium in the cylinder barrel (6) which passes through the working pressure chamber (9) delimited by the working piston (10).

6. An axial piston machine according to any one of claims 1 to 4, wherein the adjustment of the first and/or second flow cross-section (38) is coupled to a change of the displacement volume (Vg).

7. An axial piston machine according to one of claims 1 to 4, wherein the rocking cradle (13) is traversed by a pressure medium flow path (34) starting from the pressure chamber (9; 15) directly towards the relief pressure region (32; 232).

8. The axial piston machine as claimed in one of claims 1 to 4, wherein the first adjustable flow cross section is formed by a first throttle device (38) and/or wherein the second adjustable flow cross section is formed by a second throttle device.

9. An axial piston machine according to claim 8, wherein the throttling device is constructed by a controllable valve (38) or a controllable diaphragm.

10. An axial piston machine according to one of claims 1 to 4, wherein the relief pressure region is defined by at least one plain bearing-side relief pressure packet (232) which is formed in a bearing surface of the plain bearing (30), and/or wherein the relief pressure region is defined by at least one rocking cradle-side relief pressure packet (32) which is formed in a bearing surface (39) of the rocking cradle (13) which faces the plain bearing (30).

11. Axial piston machine according to claim 10, with a neutral point of the rocking cradle (13) in which the displacement volume (Vg) is zero and in which the slide bearing-side relief pressure package (232) overlaps the rocking cradle-side relief pressure package (32) at least in sections.

12. Axial piston machine according to claim 10, with a neutral plane (40) of the rocking cradle (13), in which the rocking axis lies and relative to which the bearing surface (39) of the rocking cradle (13) extends symmetrically and the rocking cradle-side relief pressure package (32) asymmetrically.

13. An axial piston machine according to one of claims 1 to 4, having a plurality of slide bearing-side relief pressure packs (232) arranged at a distance from one another in the pivoting direction and/or a plurality of pivoting cradle-side relief pressure packs arranged at a distance from one another in the pivoting direction.

14. An axial piston machine according to one of claims 1 to 4, wherein a plurality of the relief pressure packs (232) can be supplied with pressure medium via in each case one adjustable flow cross section (38) or via a common adjustable flow cross section (38).

15. The axial piston machine as claimed in claim 6, wherein the adjustment of the first and/or second flow cross section (38) is coupled to a change of the pivot angle (α) of the pivoting cradle (13).

16. The axial piston machine as claimed in claim 1, wherein the first adjustable flow cross section (38) is delimited by the running surface (12) and the working piston (10).

17. The axial piston machine as claimed in claim 1, wherein the first adjustable flow cross section (38) is delimited by a sliding surface (39) of the rocking cradle (13) and a sliding shoe (11) of the working piston (10).