EP2145107A1

EP2145107A1 - Retaining segment

Info

Publication number: EP2145107A1
Application number: EP08758518A
Authority: EP
Inventors: Herbert Dreher; Clemens Krebs
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2007-05-14
Filing date: 2008-05-14
Publication date: 2010-01-20
Anticipated expiration: 2028-05-14
Also published as: EP2145107B1; US20100300281A1; US8555773B2; JP2010526247A; JP5031891B2; WO2008138606A1; CN101680436A; CN101680436B; DE102007022568A1

Abstract

The invention relates to a retaining segment (17, 38) for retaining a back-up plate of a hydrostatic piston machine. The retaining segment (17, 38) has a recess (20) for an actuating element of an adjusting device and a retaining surface that extends along an arc section (48). A stop surface (26, 40) is formed on the retaining segment (17, 38).

Description

Retaining segment

The invention relates to a hold-down segment for

Holding down a retraction plate of a hydrostatic piston machine.

In hydrostatic axial piston machines must be ensured in particular during the suction stroke that

Sliding shoes, with which the longitudinally displaceably mounted pistons are supported on a running surface of a pivoting cradle, remain in contact with the running surface. For this purpose, a retraction plate is used, which engages around the sliding shoes and thus holds in contact with the running surface of the pivoting cradle. To set the position of the retraction plate relative to the tread of the pivoting cradle, it is known to use hold-down segments. These hold-down segments also have a receptacle for an actuator and are firmly connected to the pivoting cradle. To adjust the swivel angle and thus the stroke volume of the axial piston machines acts an adjusting device on the recording with the hold-down segment together. The screwed down with the pivot cradle hold down segment thus transmits the force generated by the actuator to the pivoting cradle and turns it in a pivoting pivot bearing. Furthermore, it is known to provide a pressure feed-through in the hold-down segment, via which pressure medium can be fed to the hydrostatic swivel weighing relief. These

Pressure medium supply has a pressure medium input. This pressure medium supply is arranged on the hold-down segment, that it is located in the mounted hold-down segment in the pivot axis of the pivoting cradle. With a separate pressure feed bar can thus Pressure medium can be supplied to relieve the pivoting cradle.

For holding down the retraction plate, a hold-down surface is formed on the hold-down segment, which extends along a circular arc portion. When the hold-down segment is mounted, this hold-down surface bears against the return plate, thus preventing the return plate from lifting.

For securing emergency running properties of the axial piston machine, the known

Hold-down segments made of brass or bronze. The emergency running properties of brass or bronze are known. However, since brass or bronze is a relatively soft material, the functionality of the hold-down segment may be limited only to the functions described above such as the transmission of a low force and the holding down of the retraction plate. However, this requires that additional functions, such as e.g. the coupling of a high pressure adjustment and a swivel angle limitation, must be provided at other locations of the axial piston machine. Ultimately, it comes thus to an increase in the space of the axial piston machine.

It is therefore the object of the invention to provide a hold-down segment which allows a higher integration of functions of the axial piston machine.

The object is achieved by the hold-down segment according to the invention with the features of claim 1. The hold-down segment according to the invention is provided for holding down a retraction plate of a hydrostatic piston machine. It has a receptacle for an actuating element of an adjusting device and a hold-down surface which extends along a

Circular arc section extends. To form at least one stop surface on the hold-down segment according to the invention. Such a stop surface can cooperate, for example, to limit the movement of the pivoting cradle with an adjustable stop. Since when approaching the end position of the pivoting cradle by the force of a high-pressure adjusting device, the pivoting cradle or the hold-down segment is pressed in each case against the adjusting screw of the limiting device, that is

Hold-down segment exposed to this stop surface a considerable burden.

In the dependent claims advantageous developments of the hold-down invention are formed.

Furthermore, it is advantageous to form the stop surface and the receptacle for the actuating element at opposite ends of the same hold-down segment and to orient it to a side facing away from a mounting surface of the hold-down segment. By such an arrangement of the receptacle for an actuating element and the stop surface for limiting the movement of the pivoting cradle, a favorable introduction of force into the holding-down segment and thus ultimately into the pivoting cradle is achieved. The force is applied both for the force and for the limiting force on the same component. The stop surface is preferably designed crowned. The center of the crown is on the mounting surface of the hold-down segment facing Side of the stop surface. Such an arrangement of the center of the crown and a crowned design of the stop surface ensures that the introduction of force, which takes place through the limiting device, can be guided through the center of the crown. With respect to the pivoting cradle thus the force is always equal and in particular independent of the set Schwenkwiegebegrenzung.

Furthermore, it is preferable to provide an even higher integration of the functionalities in the hold-down segment. For this purpose, a further stop surface is formed on the hold-down segment, which is provided on the same side of the hold-down segment as the receptacle for the actuating element. This further stop surface is preferably oriented the same as the mounting surface of the hold-down segment. Thus, the receptacle and the further stop surface are arranged in opposite directions at the same end of the hold-down segment.

The circular arc section, along which the hold-down surface extends, preferably has a wrap angle of approximately 90 degrees. With such an opening angle results in a favorable ratio of weight to contact surface between the

Retraction plate and the hold-down segment. When mounting the hold-down on the pivoting cradle is thus achieved that during the strongest stroke and thus the largest power transmission to the retraction plate during a suction stroke of a piston, the retraction plate is pressed against the hold-down of the hold-down segment. In the area of the greatest power transmission to the retraction plate, the retraction plate is thus supported via the hold-down surface. Upon further circulation of the retraction plate, the required forces to the Slider to keep on the tread of the pivoting cradle, smaller or even act in the opposite direction. As a result, formation of a hold-down surface with a wrap angle of about 90 degrees is sufficient to securely prevent distortion of the return plate.

During operation of an axial piston machine, a lubricant film is built up between the hold-down surface of the hold-down segment and the corresponding sliding surface on the retraction plate. In order to promote the formation of such a lubricant film between the surface of the retraction plate and the hold-down surface, an inclined surface portion is formed on the hold-down segment at at least one end of the hold-down surface so that the distance between the mounting surface and the hold-down surface increases toward the end of the hold-down surface. Such an inclined surface can be provided in particular at both ends of the hold-down surface, if the

Hold-down segment is provided for use in an axial piston machine provided for two directions of rotation. Such inclined surface portions promote the entrance of pressure medium, which is located on the retaining plate and thus improve the formation of a lubricant film between the retraction plate and the hold-down segment.

The hold-down segment according to the invention is preferably made of tempered steel and is nitrocarburized and oxidized. By tempering, nitrocarburizing and oxidizing the steel of the hold-down segment, a high strength and wear resistance of the component is achieved. Thus, not only the hold-down function for the retraction plate can be achieved, but it can Further functions are integrated into the hold-down segment, such as the transmission of the forces introduced by the high-pressure adjustment device and stops. Nitrocarburizing alone, however, would have the consequence that the sliding properties of the

Hold down segment on the hold-down surface and the inclusion of the adjusting would worsen without a lubricant film. The hold-down segment is therefore also oxidized. The oxidation of the nitrocarburized steel achieves good lubricity and good run-in behavior of the hold-down segment. Only thereby can be ensured despite a possible integration of other functions that holding down the retraction plate, especially during the startup phase of the axial piston machine does not lead to high friction between the hold-down and the retraction plate.

It is possible by the use of nitrocarburized steel, which is oxidized, the functions of

Hold down the retraction plate and the function of the swivel angle limiting to integrate by the stop surface in the hold-down segment.

Furthermore, it is advantageous that the hold-down segment has a hold-down surface. This hold-down surface is formed of a brass or a bronze material. Alternatively, it can be advantageously provided to form the hold-down surface of a plastic material.

According to a further preferred embodiment, the entire hold-down segment may consist of brass or bronze or else of a plastic. The formation of parts or the entire hold-down segment of brass or Bronze or plastic has the advantage that the emergency running properties of a piston engine, in which the hold-down segment according to the invention is arranged, are improved. Even with the absence of lubricant thus the life of the axial piston machine is significantly increased.

According to a further advantageous development, a magnet is provided on the hold-down segment. This magnet is used to detect the pivot angle of the

Swivel cradle and thus allows a conclusion on the set delivery volume or slip volume of the reciprocating engine. It is particularly preferred if the magnet is connected to the hold-down segment, that the magnet is arranged in a pivot axis S or at least in the vicinity of the pivot axis S. The position of the magnet during rotation of the pivoting cradle about the pivot axis S is largely retained, so that the detection of a rotation of the magnet, for example with the aid of a Hall sensor is easily possible.

A preferred embodiment is explained in more detail in the following description with reference to the accompanying drawings. Show it:

Fig. Leinen longitudinal section through an axial piston machine with the hold-down invention;

Fig. 2 is an illustration of a control system of the axial piston machine of Fig. 1 with a first

Actuator and a second actuator and using a first hold-down segment and a second hold-down segment; 3 shows a first perspective view of a hold-down segment according to the invention;

4 shows a second, partially cutaway representation of a hold-down segment according to the invention;

5 shows a third perspective view of the hold-down segment according to the invention of FIG. 3;

6 shows a further illustration of the positioning system with a hold-down segment according to the invention in a partially sectioned illustration;

7 shows a further illustration to illustrate a possible swivel angle detection by means of a magnet arranged in the swivel axis area;

8 shows an alternative embodiment of a hold-down surface on the hold-down segment; and

a still further embodiment of a hold-down surface on the hold-down segment.

1 shows a sectional illustration of an axial piston machine 1 according to the invention, wherein the sectional plane, however, extends eccentrically parallel to a rotation axis of the axial piston machine 1. The axial piston machine 1 has a cylinder drum 2, in which a plurality of cylinder bores are distributed in a manner not shown distributed over a circumferential circle. In the cylinder bores pistons are arranged longitudinally displaceable, which promote a pressure medium by their stroke movement when it is a pump in the illustrated axial piston machine 1. The axial piston machine 1 has a housing, which consists of a first cup-shaped housing part 3 and a second housing part, which is designed as a flange 4. A drive shaft, not visible in FIG. 1, is rotatably mounted in the flange part 4 and the first, cup-shaped housing part 3 and connected in a rotationally fixed manner to the cylinder drum 2. Upon rotation of the drive shaft, the cylinder drum 2 is rotated by the non-rotatable connection. The in the

Cylinder drum 2 arranged, longitudinally displaceable piston are supported in a known manner via sliding blocks on a pivoting cradle 5 from. The pivoting cradle 5 has a running surface 6 for this purpose. To lift off the shoes from the tread 6 during a suction stroke

To prevent pivoting cradle 5, a retraction plate 7 is provided. The retraction plate 7 is held at a fixed distance from the running surface 6 of the pivoting cradle 5 and thus prevents lifting of the sliding shoes from the running surface 6. To allow a rotational movement of the pivoting cradle 5, the sliding blocks are pivotally connected to the piston. Depending on the inclination of the pivoting cradle 5, the pistons in the cylinder drum 2 thus carry out a lift of different magnitude per revolution of the drive shaft or the cylinder drum 2.

On its side facing the flange part 4, the pivoting cradle 5 has a pivotal pivot bearing 8. For this purpose, at least one first storage area is formed on the pivoting cradle 5, which has a corresponding bearing area

Recess 9 of the flange 4 forms a sliding bearing. The design of the pivot angle bearing of the pivoting cradle 5 will be explained below with reference to FIGS. 2 and 6. The pivoting cradle 5 is rotatable about a pivot axis S by rotating the pivoting cradle 5 in the pivoting pivot bearing. This changes the inclination of the running surface 6 relative to the axis of rotation of the cylinder drum 2.

To adjust the inclination of the pivoting cradle 5 and thus the stroke of the piston in the cylinder drum 2 during rotation of the cylinder drum 2, a control system is provided within the housing of the axial piston machine 1. The adjusting system comprises at least a first adjusting device 10. The first adjusting device 10 has a first actuating piston 11. The first control piston 11 defines with its first end 12 a pressure chamber 13. The pressure chamber 13 is formed in a bottom of the cup-shaped housing part 2. To the training of

Pressure chamber 13, a blind bore 14 is introduced into the bottom of the cup-shaped housing part 3, in which a bushing 15 is inserted. The bushing 15 is preferably pressed into the blind bore 14. The inner wall of the bush 15 serves the first end 12 of the actuating piston 11 as a sliding surface and cooperates sealingly with the first end 12 of the first actuating piston 11. The first end 12 of the actuating piston 11 is not cylindrical, but has a slightly convex shape to prevent tilting in the socket 15 at an oblique position of the actuating piston 11 relative to the longitudinal axis of the bushing 15. In the crowned region of the first end 12 of the actuating piston 11, a sealing ring could also be arranged.

At a second remote from the first end 12 second

End 16 of the actuating piston 12, a ball head is formed. The ball head is connected to a hold-down segment 17 so that both tensile and compressive forces can be transmitted. The hold-down segment 17 is firmly connected by means of screws with the pivoting cradle 5. The hold-down segment 17 is screwed onto the running surface 6 in an outer region of the pivoting cradle 5. The hold-down segment 17 also has a hold-down surface 19, which engages over the retraction plate 7 and rests against the retraction plate 7 and thus ensures a constant distance of the retraction plate 7 from the running surface 6 of the pivoting cradle 5.

For fixing the ball-head-shaped second end 16 of the actuating piston 11, a spherical recess 20 is provided in the hold-down segment 17, which encloses the ball-head-shaped second end 16 of the actuating piston 11. The connection of the actuating piston 11 with the hold-down segment 17 is designed as a locked connection. That is, the ball-head-shaped second end 16 is enclosed further than the equator by the spherical recess of the hold-down segment.

Inside the adjusting piston 11 in the first adjusting device 10, a lubricant channel 21 is formed. The lubricant channel 21 extends from the first end 12 of the actuating piston 11 to the second end 16. Thus, the lubricant channel 21 connects the pressure chamber 13 with the ball-head-shaped second end 16 of the actuating piston 11. A pressure prevailing in the pressure chamber 13 thus ensures a discharge of Pressure medium at the ball-head-shaped second end 16 of the actuating piston 11. Thus, the articulated connection between the actuating piston 11 and the hold-down segment 17 is lubricated and hydrostatically relieved.

In the figure 1 it is assumed that the first adjusting device 10 is provided for pivoting the axial piston machine 1 in the direction of maximum displacement volume. The pressure chamber 13 For this purpose, it is connected to the delivery side of the axial piston machine 1 designed as a pump. The pending in the pressure chamber 13 high pressure is also used to cause a hydrostatic discharge of the pivoting cradle 5 in the flange 4. This is both in the

Hold-down segment 17 and in the pivoting cradle 5 a pressure medium channel 22 and 23, respectively. In a manner not shown, the pressure medium channel 23 of the pivoting cradle 5 is connected outside the section shown in FIG. 1 to the bearing area 8. That from the

Pressure chamber 13 originating, pressurized pressure medium thus exits between the recess 9 and the bearing portion 8 of the pivoting cradle 5, and thus ensures a hydrostatic discharge of the pivoting cradle 5. This leads to a significant reduction of the required actuating forces.

In order to enable a positioning of the hold-down segment 17 relative to the pivoting cradle 5, a dowel pin 24 is provided, which is inserted into a bore in the pivoting cradle 5 and a corresponding bore in the hold-down segment 17. Furthermore, an adjustable first limiting device 25 is provided in the pot-shaped housing part 3 in the region of an end remote from the ball joint connection between the actuating piston 11 and the hold-down segment 17 of the hold-down segment 17. The first limiting device 25 cooperates with a first stop surface 26, which is formed on the hold-down segment 17. The first abutment surface 26 is designed crowned, so that regardless of the setting of the first limiting device 25, the introduction of force by the limiting device 25 perpendicular to the first abutment surface 26 and thus through the center of the Crowning takes place. The center of this crowning is viewed from the stop surface in the direction of the pivoting cradle. 5

The first limiting device 25 comprises a

Adjustment screw 27, which is screwed into a designated thread in a housing bore. Depending on the depth of engagement, the maximum deflection of the pivoting cradle 5 in a first direction of movement through the first

Clamping device 25 fixed. The housing bore is arranged in the region of the jacket of the cup-shaped housing part 3. It encloses with the axis of rotation at an angle such that the central axis of the adjusting screw 27 extends through the center of the crowning of the stop surface 26.

The first adjusting device 10, the first limiting device 25 and the first hold-down segment 17 are all a first

Movement of the pivoting cradle 5 assigned. While the first adjusting device 10 attempts to adjust the pivoting cradle 5 in a first direction of movement, the first limiting device 25 serves as an adjustable stop and thus limits the maximum adjustment in this first direction of movement. To secure the adjusting screw 27 in a selected position, a lock nut 28 is provided. The lock nut 28 also serves to seal the housing interior from the environment. The safety cap 29 prevents unauthorized changing of the setting values.

In order to always ensure the safety of the axial piston machine 1 even with an accidental adjustment of the adjusting screw 27, is also on the the same end of the hold-down segment 17, where the ball connection between the second end 16 of the actuating piston 11 and the first hold-down segment 17 is formed, a further stop surface 30 is formed. The further stop surface 30 is formed on the flange part 4 facing side and cooperates with a counterpart of the flange 4 to a safety stop. Thus, even with completely unscrewed adjusting screw 27, an adjustment only to the response of the safety stop.

During an adjustment of the axial piston machine 1 in the direction of maximum stroke volume, the safety stop between the flange part 4 and the further stop face 30 of the first hold-down segment 17 is preferably formed.

The first adjusting device 10 and the first limiting device 25 are, as can be seen directly from FIG. 1, arranged in a plane which runs parallel to the axis of rotation of the cylindrical drum 2 and which is in particular perpendicular to the pivot axis S of the pivoting cradle 5. The force direction both to initiate the actuating force by the first adjusting device 10 and the direction of force when it stops at the adjustable first

Limiting device 25 is thus also in the plane formed parallel to the axis of rotation. Since this plane runs simultaneously through a first bearing area formed on the pivoting cradle 5 and the flange part 4, torsional forces on the pivoting cradle 5 are avoided. In order to bias the axial piston machine 1 in the direction of maximum displacement volume even at pressure-free pressure chamber 13, an elastic element is provided on the first adjusting device 10. The elastic element is designed as a spring 33 in the illustrated embodiment. The spring 33, which is preferably a steel spiral spring, is supported on the one hand on a first spring bearing 31 formed in the vicinity of the second end 16. The spring bearing 31 is formed as a radial shoulder in the actuating piston 11 and has a slightly extending in the axial direction in the direction of the first end 12 of the actuating piston 11 guide portion for centering the spring 33. At the opposite end of the spring 33, the spring 33 abuts against a second spring bearing 32. The second spring bearing 32 is slotted c-shaped and is pushed laterally on the adjusting piston 11 when the spring is compressed. In this case, the second spring bearing 32 is supported against the piston end 12. The spring bearing 32 also has a guide portion which extends in the axial direction. The spring bearing 32 is arranged in a centering recess 34 of the housing part 3 and rests there against the bottom of the cup-shaped housing part 3. The spring bearing 32 is preferably at the same time at the bottom of the cup-shaped housing 3 at the bottom of the centering recess 34 and at the oriented to the interior of the housing of the axial piston 1 end of the bushing 15 at.

FIG. 1 shows a section through the first adjusting device 10 and the first adjustable limiting device 25. The first adjusting device 10 is provided for adjusting the axial piston machine 1 in the direction of larger displacement and can therefore be used as Ausschwenkvorrichtung be designated. This is true when the axial piston machine 1 as a hydraulic pump z. B. is used in the open circuit and is provided for promotion in one direction only.

In the axial piston machine 1, a second adjusting device 35 is further provided, which in the illustration of FIG. 1, however, is not recognizable due to the position of the cut. The second adjusting device 35 also has a second variable limiting device 39 and substantially corresponds to the first adjusting device 10. The second adjusting device 35 and the second limiting device 39 are again arranged in a common plane, this further plane parallel to the plane of the first adjusting device 10 and the first

Clamping device 25 is located. The two planes are preferably symmetrical to the axis of rotation of the cylinder drum 2.

This arrangement is shown in Fig. 2, in which the individual components of the control system are shown again in a perspective view. In this case, the components of the axial piston machine 1 that do not concern the positioning system are omitted for easier traceability.

It can be seen that the first adjusting device 10 and the second adjusting device 35 lie on opposite sides with respect to the axis of rotation. The second adjusting device 35 of the actuating system has an actuating piston, which is mounted with its first end in a second sleeve 36. The second sleeve 36 is also inserted in a blind bore in the bottom of the cup-shaped housing part 3. This will be a second pressure chamber formed in the sleeve 36, which is closed by the bottom of the cup-shaped housing part 3, as in the first adjusting device 10. The pressure chamber or the pressure chamber is limited by a likewise spherical control piston disc. Over the entire adjustment path of the adjusting system, the respectively crowned adjusting piston disk of both the adjusting piston 11 and the adjusting piston of the second adjusting device 35 is guided in the bush 15 or the further bushing 36. At the other end of the actuating piston of the second actuator 35 is also a

Ball joint formed. The second end 37 of the actuating piston of the second adjusting device 35 is also inserted into a spherical recess of a second hold-down segment 38. The second hold-down segment 38, like the first hold-down segment 30, is connected to the pivoting cradle 5 by means of screws 18. The first and second hold-down segments 17 and 38 are preferably identical. The first hold-down segment 17 extends substantially along the plane in which the first adjusting device 10 and the first

Limiting device 25 are arranged. Accordingly, the second hold-down segment 38 extends substantially along a further plane in which the second adjusting device 35 and a second variable limiting device 39 are arranged. The second variable restricting device 39 is similar in construction to the first variable restricting device 35, so the description will be omitted.

Considering a cross section through the axial piston machine 1, which typically has a housing with a rectangular or square cross section, the adjusting devices 10 and 35 are on a first diagonal in the region of the inner corners of the housing and the adjustable limiting devices 25 and 39 arranged on a second diagonal in the region of the inner corners of the housing. Dividing the axial piston machines in FIG. 4 into such a section

Quadrants, the first actuator 10 in the first quadrant, the first restrictor 25 in the fourth quadrant, the second actuator 35 in the third quadrant, and the second adjustable restrictor 39 in the second quadrant.

At the second hold-down segment 38, a stop surface 40 is also formed, which is designed crowned. The spherical shape of the abutment surface 40 has, as in the first hold-down segment 30 with the result that regardless of the selected setting of the variable limiting device 39, the force is always perpendicular to the stop surface 40. To form a safety stop, a further stop surface 41 is also formed on the second hold-down segment 38. The further stop surface 41 is formed at the same end of the second hold-down segment 38 as the ball joint connection with the actuating piston of the second actuator 35.

In FIG. 2 it can be seen that the pivoting pivot bearing 8 of the pivoting cradle 5 is formed by a first bearing surface 8.1 and a second bearing surface 8.2. The first bearing surface 8.1 extends in a width in the direction of the pivot axis S, so that the plane in which the first adjusting device 10 and the first adjustable limiting device 25 are arranged, ie in which the directions of force by the first adjusting device 10 and the first adjustable Limiting device 25 are, passes through the first bearing surface 8.1. In a corresponding manner, the second bearing surface 8.2 also extends over a width in the direction of the pivot axis S, so that the further plane in which the second adjusting device 35 and the second limiting device 39 are arranged, extends through the region of the second bearing surface 8.2.

The two hold-down segments 17, 38 are the same. Such a hold-down segment 17, 38 is shown enlarged in a perspective view in FIG. The hold-down segment 17, 38 has a substantially rod-shaped geometry. At a first end 45, the receptacle for the actuating element of the first adjusting device 10 is formed. In the case of the axial piston machine 1 shown, the actuating piston 11 is the actuating device. The receptacle is in the form of a spherical recess 20. The spherical recess 20 is mounted on an outwardly inclined surface, thereby enclosing the intended use ball-spherical design of the second end 16 of the actuating piston 11 so far that train and compressive forces are transferable. For this purpose, an undercut is formed on the actuating piston 11 at the transition between the ball-head geometry and an actuating piston shaft, which allows pivoting of the actuating piston 11 relative to the hold-down segment 17 in the functional level by adjusting device and limiting device, in addition, the spherical end 16 of the actuating piston on the ball equator on cylindrical a smaller one

Flattened diameter, so that in an inclined state of the ball head is inserted into the recess 20. For this purpose, an inclination of the actuating piston 11 is required transversely to the functional direction, ie outside the functional level. During normal operation will be against such an angle between the hold-down segment 17 and the actuating piston 11 is not reached, so that slipping out of the ball-head-shaped second end 16 of the actuating piston 11 from the recess 20 can not occur.

At the second end 46 facing away from the first end 45 of the hold-down segment 17, the ball-shaped stop surface 26 is formed. The center of the spherical geometry of the stop surface 26 is located in the

Fig. 3 below the stop surface 26 and thus on the tread 6 of the pivoting cradle 5 facing side of the stop surface 26. The first end 45 to the second end 46 connecting portion of the hold-down segment 17, 38 is executed straight on one side. Thus, a flat side surface 47 is formed on the hold-down segment 17, 38. The side surface facing away from this, which is oriented during assembly on the pivoting cradle 5 in the direction of the center of the pivoting cradle 5 or its tread 6, on the other hand, is designed with a curvature 48. The curvature 48 or the hold-down surface 19 formed there is explained below with reference to FIG. 5.

For mounting the hold-down segment 17, 38 on the

Running surface 6 of the pivoting cradle 5 is a mounting surface 49 is provided. The mounting surface 49 is designed as a flat surface and extends over a large part of the total length of the hold-down segment 17, 38. The entire hold-down segment 17, 38 is made slightly longer than the contact surface with the pivoting cradle 5, so that the first end 45 and the second end 46 protrude slightly above the pivoting cradle 5. Thus, both the force through the variable limiting device on the stop surface 26 than on the adjusting force is supplied via the recess 20 with a relatively large lever, so that even comparatively small forces are sufficient to allow an adjusting movement or a limitation of the adjusting movement safely. Thus, the pivoting cradle 5 itself can be made smaller overall, resulting in a reduction in the overall weight of the axial piston machine 1.

In order to achieve reliable operation of the axial piston machine 1, the inventive

Hold-down segment 17, 38 made of tempered steel. This steel is nitrocarburized and oxidized. By tempering and nitrocarburizing the steel, a high strength or wear resistance and surface hardness of the component is achieved. By such a high strength, the abutment surface 26 can be formed on the hold-down segment 17, 38. Therefore, even in a continuous operation, the stop surface 26 does not wear so far that this could lead to a change in the end position of the pivoting cradle 25. This is particularly advantageous against the background of a safe operation of the operating with considerable pressure axial piston 1.

The length of the hold-down segment 17, 38 additionally makes it possible to provide a further stop surface 30 on the side of the first end 45 of the hold-down segment 17 that is oriented identically to the mounting surface 49. This further stop surface 30 cooperates with a counterpart which is formed in the housing of the axial piston machine 1. The further abutment surface 30 thus forms a safety stop, whereby all the forces influencing the position of the pivoting cradle 5 are introduced exclusively at the hold-down segment 17, 38. For mounting the hold-down segment 17, 38 on the pivoting cradle 5 screw 18 are provided, as has already been explained with reference to FIGS. 1 and 2. To accommodate the screws 18, holes 50, 51 are formed in the hold-down segment 17, 38. The bores 50, 51 penetrate the hold-down segment 17, 38 and are formed near the first end 45 and the second end 46. In the embodiment shown in FIG. 3, moreover, a pressure medium supply 52 is provided. The pressure medium supply 52 is connected via a pressure medium channel 53 with the mounting surface 49, so that pressure medium can be supplied to the mounting surface 49 via the pressure medium supply 52. This is shown in FIG. 4, which shows a section through the hold-down segment 17, 38 according to the invention. The pressure medium bore 53 extends from the first end 45 of the hold-down segment 17, 38 to the pressure medium receiving 52. In this case, it penetrates the

Bore 51 and is connected to a transverse bore 54. At a corresponding point to the transverse bore 54, a further pressure medium channel in the pivoting cradle 5 is formed. This will be clarified below with reference to FIG. 6. About this channel system pressure medium, which via a pressure medium line, not shown in the figures on the

Pressure medium supply 52 is supplied to the storage areas of the pivoting cradle 5 are supplied. Preferably, however, an alternative embodiment is used, wherein the

Pressure medium channel 53 is connected to the spherical recess 20. Thus, the pivoting cradle 5 supplied pressure medium is removed via the control piston 11 from the pressure chamber 13. FIG. 5 shows a third perspective view of the hold-down segment 17, 38 according to the invention. In particular, it can be seen there that in the region of the curvature 48, the hold-down surface 19 is formed. The hold-down surface 56 is introduced into the hold-down segment 17, 38, for example, by a circular cut-out from the side of the mounting surface 49. The hold-down surface 56 is formed plane-parallel to the mounting surface 49. During operation of the axial piston machine 1, the retaining plate rotates with the sliding shoes fixed therein and lies with its surface facing away from the running surface 6 of the pivoting cradle 5 against the retaining surface 19. The hold-down segments 17, 38 fixedly connected via the screw connections to the pivoting cradle 5 thus hold the return plate at a maximum distance from the running surface 6 of the pivoting cradle 5 via a positive connection. During operation, a retraction plate 5 forms between the hold-down surface 5 and the surface Lubricant film off. In order to improve the entry of lubricant during operation and thus also to improve the start-up behavior of the axial piston machine 1 and to reduce wear, at least one inclined surface 57 or 58 is formed on the hold-down surface 19.

The hold-down surface 19 extends along a circular arc section. The wrap angle of the hold-down surface 56 is about 90 degrees. The inclined surface 57 is formed so that the distance from the mounting surface 49 increases toward the end 57 'of the hold-down surface 56. This results in a wedge-shaped gap between the hold-down surface 56 in the region of at least one inclined surface 57 and the retraction plate 7. Thus, there is an insertion bevel, which promotes the entry of lubricant into the space between the hold-down surface 19 and the retraction plate 7. If the axial piston machine 1 is designed for operation in both directions of rotation, it is preferred on the hold-down segment 17, 38, as shown in FIG. 5, to provide such an inclined surface 57, 58 at both ends. The second inclined surface 58 at the other end 58 'is formed corresponding to the first inclined surface 57.

Furthermore, the further stop surface 30 can be seen well in FIG. 5. The stop surface 30 is formed at the same end 45 as the receptacle for the actuator. In this case, the stop surface 30 is oriented substantially in the direction of the mounting surface 49, but extends obliquely to this. The angle which the stop surface 30 assumes to the mounting surface 49 is dependent on the maximum pivot angle at which the further stop surface 30 is intended to cooperate with a counterpart of the housing of the axial piston machine 1 to a safety stop.

For fixing and centering of the hold-down segments 17, 38, as already explained with reference to FIG. 1, dowel pins are provided. For receiving the dowel pin, a centering hole 59 is introduced from the mounting surface 49 into the hold-down segment 17, 38.

Fig. 6 shows a partial section through

Components of the control system of the axial piston machine according to the invention 1. In particular, the course of the pressure channels in the first hold-down segment 17 and further in the pivoting cradle 5 is shown. In this case, the preferred embodiment is shown, according to the Pressure medium channel in the hold-down segment 17, 38 is connected to the spherical recess 20 of the ball joint connection. About the transverse bore 54, the pressure medium is then fed to the pivoting cradle 5. In the pivoting cradle 5, a further pressure medium channel 56 is arranged, which is connected via an input bore 56 'with the transverse bore 54 of the hold-down segment 17, 38 in connection. The further pressure medium channel 56 is connected to a first and a second bearing surface bore, wherein only the second Lägerflächenbohrung 56 '' in Fig. 6 can be seen. There, the pressure medium exits, for example, in a groove provided in the second bearing surface.

FIG. 7 shows that a magnet M is arranged coincidentally on the hold-down segment 17 in the region of the pivot axis or with the pivot axis. With the help of this magnet, rotational angle changes and thus positions of the pivoting cradle 5 can be easily detected. As a detection, for example, a Hall sensor in

Be arranged portion of the magnet, which determines its rotation contactless. The magnet M can either be arranged on the hold-down segment 17 or else be incorporated into it, for example by inserting a magnet into a recess of the hold-down segment provided for this purpose.

Figures 8 and 9 show embodiments of alternative embodiments of the hold-down surfaces 19 'and 19' '. The hold-down surface is not in the example of Figure 8 over the full length of the

Hold-down segment 17 formed. Instead, regions are formed which are raised in relation to the hold-down segment 17 which acts as a carrier. Such raised hold-down surfaces 19 'or 19 "are preferably made Brass or bronze material formed. Alternatively, they can also be made of a plastic material. The hold-down surfaces 19 'and 19''serve as sliding partners for the retraction plate 7 and can be, for example, flame-sprayed. This is shown by way of example in FIG. Alternative attachment methods are, for example, in the case of metallic hold-down surfaces 19 '' the riveting with the hold-down segment 17 as a supporting element. In this case, it is particularly preferred if the hold-down surface 19 'or 19 "is arranged toward the first end or towards the second end. Thus, the forces are introduced closer to the region of the fixation of the hold-down segment 17 on the pivoting cradle 5, whereby a deflection of the hold-down segment 17 is largely prevented.

The invention is not limited to the illustrated embodiments. In particular, it is possible to combine individual features of the illustrated embodiments in an advantageous manner.

Claims

claims

1. Hold-down segment for holding down a return plate (7) of a hydrostatic piston machine (1) with a receptacle (20) for an actuating element (11) of an adjusting device (10) and a hold-down surface (19, 19 ', 19' ') extending along a circular arc section ), characterized in that on the hold-down segment (17, 38) at least one stop surface (26, 40) is formed.

2. hold-down segment according to claim 1, characterized in that the stop surface (26, 40) and the receptacle (20) for an actuating element (11) at opposite ends (45, 46) of the hold-down segment (17, 38) are formed and to one of one

Mounting surface (49) facing away from the side are oriented.

3. hold-down segment according to claim 1 or 2, characterized in that the stop surface (26, 40) is designed crowned, wherein the center of the crown on the mounting surface (49) facing side of the stop surface (26, 40).

4. hold-down segment according to one of claims 1 to 3, characterized in that a further stop surface (30, 41) on the hold-down segment (17, 38) is formed, which is arranged at the same (45) end, as the receptacle (20). for the actuator (11).

5. hold-down segment according to claim 3, characterized in that the receptacle (20) and the further stop surface (30) are oriented in opposite directions on the hold-down segment (17, 38).

6. hold-down segment according to one of claims 1 to 5, characterized in that the circular arc section corresponds to a circular segment with an opening angle of about 90 °.

7. hold-down segment according to claim 6, characterized in that at at least one end (57 ', 58') of the hold-down surface (19) an oblique surface portion (57, 58) is formed, so that the end (57 ', 58') the hold-down surface (19) towards a distance between the mounting surface (49) and the hold-down surface (19) increases.

8. hold-down segment according to claim 7, characterized in that in the hold-down segment (17, 38) at least one pressure medium channel (53, 54) is formed, which connects the receptacle (20) for the actuating device (11) with the mounting surface (49).

9. hold-down segment according to one of claims 1 to 8, characterized in that the hold-down segment (17, 38) consists of nitrocarburized steel and is oxidized.

10. hold-down segment according to claim 9, characterized in that the hold-down segment (17, 38) has a hold-down surface 19 which is formed of a brass or bronze material.

11. hold-down segment according to claim 9, characterized in that the hold-down segment (17, 38) a Hold-down surface (19, 19 ', 19'') which is formed of a plastic material.

12. hold-down segment according to one of claims 1 to 11, characterized in that the hold-down segment (17, 38) made of brass or, bronze or plastic.

13. hold-down segment according to one of claims 1 to 12, characterized in that the hold-down segment (17, 38) is equipped with a magnet (M), which serves to detect the pivot angle of the pivoting cradle.

14. hold-down segment according to claim 13, characterized in that a magnet (M) with the hold-down segment (17, 38) is connected, which in the pivot axis (S) or in the vicinity of the pivot axis (S) is arranged.