EP1561031B1 - Axial piston machine, swash-plate and method for producing a swash-plate - Google Patents

Description

The invention relates to an axial piston machine and a designated withdrawal plate and a method for producing the retraction plate.

In an axial piston machine, a cylinder barrel rotates relative to an inclined plane. In the cylinder drum a plurality of cylinder bores are introduced, in which axially displaceably arranged pistons perform a lifting movement. To generate the lifting movement, the pistons are pivotally connected to a respective sliding block, wherein the sliding blocks are supported on the inclined plane and thus generate the stroke of the piston in a relative rotational movement. In order to ensure the engagement of the sliding shoes on the inclined plane during a suction stroke, it is known to hold the sliding shoes on the tread by means of a retraction plate.

Such a retraction plate is known for example from DE 197 51 994 A1. The retraction plate proposed there has recesses arranged on a peripheral circle, which recesses are provided for receiving the sliding shoes. In addition, a central opening is provided, with which the return plate is supported on an abutment, wherein the abutment has a spherical outer geometry and is arranged on the shaft of the axial piston machine. The central opening is surrounded by a collar. The holding force is exerted by a surface of the return plate oriented towards the oblique plane, which bears against the sliding shoes. The recesses which receive the sliding shoes are penetrated by a partially cylindrical part of the sliding shoe.

A disadvantage of the known retraction plate is that radial forces, as in the operation of the Axial piston machine between the shoe and the return plate occur, can only be transmitted to the inner surface of the recesses. In order to prevent premature wear, it is therefore necessary to provide a corresponding material thickness for the return plate, so that the length of the holes in the axial direction ensures a sufficient guide height. Associated with this is the use of machining processes which, in addition to an unnecessarily high use of material, also increase the costs of machining.

In particular, for axial piston machines in swash plate construction also the high weight of the retraction plate is a crucial disadvantage, since the retraction plate is there a rotating components.

Furthermore, it is problematic that when using a likewise proposed in DE 197 51 994 A1 proposed biased return plate, the deformation of the return plate during installation in the axial piston machine must be considered in order to achieve a parallel alignment of the holes with the cylindrical part of the shoe.

The invention has for its object to provide a retraction plate and an axial piston machine, which are easy to manufacture and which are reduced in weight with improved function, and to provide a method for the simplified production of a retraction plate.

The object is achieved by the retraction plate according to the invention according to claim 1, the axial piston machine according to the invention according to claim 12 and the method according to the invention according to claim 23.

The retraction plate according to the invention has, in addition to a collar, which at a central passage opening is formed, formed in the opposite direction guide collar. The guide collars each include a shoe receiving aperture, thereby increasing the guide height of the shoe receiving apertures relative to the thickness of the disk-shaped retraction plate. By increasing the guide height, a larger contact surface for transmitting the force in the radial direction between the slide shoe and the return plate is achieved during operation of the axial piston machine. The larger contact surface ultimately leads to an improvement of the wear properties.

At the same time, compared to the known retraction plate, the material thickness of the disc can be reduced so that there is a reduction of the rotating mass. In this case, a considerable reduction of the material is achieved in particular by the manufacturing process of the retraction plate according to the invention, since a solidification of the material is caused by the preferably cold deformation in the region of the Gleitschuhaufnahmeöffnungen.

Advantageous developments of the retraction plate according to the invention, the axial piston machine according to the invention and the method according to the invention for producing the retraction plate are specified in the subclaims.

In particular, it is advantageous that the inner surface of the guide collar has the shape of a cylinder jacket surface, wherein it is particularly advantageous that the height of the cylinder jacket surface has a significant portion of the total height of the Gleitschuhaufnahmeöffnungen and thus the guide height. Thus, the greatest possible portion of the usable height of the retraction plate is used to form the guide height, which in turn reduces the wear occurring at the contact surface between the cylindrical portion of the shoe and the retraction plate.

It is furthermore particularly advantageous that both the openings in the retraction plate are produced starting from a basic body in a single step by a combined stamping and embossing process, and also that the edge surrounding the openings is reshaped into the collar or the guide collar. Further processing steps which increase the processing time are thus kept to a minimum. In particular, the amount of machining is reduced to flattening and creating a high surface finish of the surface surrounding the central through-hole in a radially outward direction.

By the main body, which has the shape of a circular disk, a high load capacity is ensured, since the material of the main body is maintained between the Gleitschuhaufnahmeöffnungen. The resulting stiffness improves the endurance, especially with regard to material fatigue.

In addition, it is advantageous that in the region of the central passage opening only a small portion is hardened by means of a laser process. The usual default of the retraction plate during curing, which requires a post-processing to obtain a flat surface, can be omitted. Thus, only a small area is cured, in which such a surface treatment is required in view of the subsequent wear resistance.

Fig. 1

eine Schnittdarstellung einer erfindungsgemäßen Axialkolbenmaschine;

Fig. 2a, b

eine erfindungsgemäße Rückzugplatte vor und nach der spanenden Bearbeitung;

Fig. 3a, b.

eine Vergrößerung im Ausschnitt IIIa bzw. IIIb aus der Fig. 2a, b;

Fig. 4

eine Aufsicht auf eine erfindungsgemäße Rückzugplatte; und

Fig. 5

eine perspektivische Darstellung einer erfindungsgemäßen Rückzugplatte.

A preferred embodiment is shown in the drawing and will be explained in more detail with reference to the following description. Show it:

Fig. 1

a sectional view of an axial piston according to the invention;

Fig. 2a, b

a retraction plate according to the invention before and after the machining;

Fig. 3a, b.

an enlargement in the section IIIa or IIIb from the Fig. 2a, b;

Fig. 4

a plan view of a retraction plate according to the invention; and

Fig. 5

a perspective view of a retraction plate according to the invention.

Before discussing the details of the axial piston machine according to the invention or the retraction plate according to the invention, the essential components of an axial piston machine, as well as their function for better understanding of the invention will be explained first. Fig. 1 shows an axial piston machine 1, which has a rotatably mounted in a housing 2 shaft 3, on which a cylinder drum 4 is arranged, wherein the cylinder drum 4 and the shaft 3 are rotatably connected to each other. The shaft 3 penetrates the cylinder drum 4 and is mounted on both sides of the cylinder drum 4 in each case a rolling bearing 5 and 6, wherein an outer bearing ring 7 of the rolling bearing 6 is inserted into a corresponding recess of a housing cover 8.

In the cylinder drum 4 distributed over the circumference a plurality of cylinder bores 9 are formed, wherein the central axes of the cylinder bores 9 extend parallel to the central axis of the shaft 3. In the cylinder bores 9 axially displaceable piston 10 are used, which on the side facing away from the housing cover 8 side have a spherical head 11 which cooperates with a corresponding recess of a shoe 12 to a hinge connection. By means of the sliding blocks 12, the pistons 10 are supported on a swash plate 13. Upon rotation of the cylinder drum 4, the pistons 10 therefore execute a stroke movement in the cylinder bores 9. The height of the Hubs is determined by the position of the swash plate 13, wherein the position of the swash plate 13 in the embodiment by an adjusting device 14 is adjustable.

The cylinder drum 4 has a central opening 15, in which a compression spring 16 is arranged, which is stretched between a first spring bearing 17 and a second spring bearing 18. The first spring bearing 17 is fixed by the shaft 3 in the axial direction, the second spring bearing 18, however, is formed in the illustrated embodiment by an inserted into a groove of the cylinder drum 4 Seeger ring. Due to the force of the compression spring 16, therefore, the cylinder drum 4 is moved in the axial direction so far that it rests sealingly with its end face 19 on a control plate 20.

The arranged in the control plate 20 control openings 22 and 23 are on their side remote from the cylinder drum 4 side in permanent contact with at least one high-pressure or low pressure connection. A high-pressure or low-pressure connection is shown by way of example and provided with the reference numerals 26 and 26 '. The cylinder bores 9 are open via openings 21 to the end face 19 of the cylinder drum 4. The openings 21 sweep with a rotation of the cylinder drum 4, a sealing environment 27 of the control plate 20 and are connected during a rotation alternately with the control ports 22 and 23 of the high-pressure or low-pressure connection.

In the axial direction, the control plate 20 is supported on the housing cover 8. With a dowel 31, the control disk 20 is secured against rotation.

Despite the processing of the end face 19 of the cylinder drum 4 and the sealing environment 27 of the control plate 20 with a high Surface quality allow leakage occurs between the cylinder drum 4 and the control plate 20, which is also required for forming a hydrodynamic sliding bearing. The central opening 15 of the cylinder drum 4 defines an internal leakage volume 44, which receives a portion of the leakage oil. In order to prevent a pressure build-up in the self-contained inner leakage volume 44, a connection, not shown, between the inner leakage volume 44 and an outer leakage volume 45 of the remaining housing volume is provided, so that a pressure compensation is possible. The collected in the outer leakage volume 45 of the housing leakage fluid is supplied to the pressure medium circuit in a manner not shown again.

In the axial piston machine 1 in swash plate design shown in FIG. 1, as already stated, the lifting movement of the piston 10 is generated by the swash plate 13, which is arranged obliquely with respect to the central axis of the rotating cylinder drum 4. In operation of such an axial piston machine 1 e.g. As a pump, the cylinder drum 4 is rotated by driving the shaft 3. Due to the pressure prevailing in the cylinder bores 9, the slide shoe 12 is held in contact with the swashplate 13 with a sliding surface 25 during a pressure stroke. During the second half of a revolution of the cylinder drum 4, however, a negative pressure arises in the cylinder bores 9, through which the sliding shoes 12 could lift off the swashplate 13, in particular during operation of the axial piston machines 1 in an open circuit. To prevent this, a retraction plate 24 is provided, which exerts a holding force on the sliding blocks 12 and thus holds them on a running surface 28 of the swash plate 13.

The retraction plate 24, which will be explained in more detail below with reference to Figures 2 to 5, has a central passage opening 32, with she is supported on an abutment 29. The counter-bearing 29 is fixed in the illustrated embodiment of the shaft 3, so that it is axially non-displaceable in the direction of the housing cover 8. The counter-bearing 29 has a spherical outer contour, which corresponds to a central through-opening 32 bounding surface and allows a change in the inclination angle of the return plate 24 relative to the shaft 3. In order to transfer a holding force between the retraction plate 24 and the shoes 12, a holding surface 33 is formed on the shoe 12, which is in contact with a flat first surface 34 'of the retraction plate 24. The sliding shoes 12 also have a guide section 35. The guide portion 35 of a shoe 12 penetrates a shoe receiving hole 36 provided in the retreating plate 24, respectively. The radial extent of the Gleitschuhaufnahmeöffnungen 36 is greater than the cylindrical in this area guide portion 35 of the sliding blocks 12th

In order to allow a tilting of the sliding blocks 12 relative to the piston 10 in accordance with the inclination of the swash plate 13, a recess 37 is provided in the guide shoe 35 in the sliding block 12, whose geometry corresponds to the spherical head 11 of the piston 10. The spherical recess 37 is closed so far around the spherical head 11 that also tensile forces between the shoe 12 and the respective piston 10 are transferable. The contact surface is supplied by a lubricating oil bore in the piston 10 from the cylinder bore 9 with lubricant.

FIG. 2 a shows a retraction plate 24 in which the guide collar 38 and the collar 39 of the central passage opening 32 have already been formed from a disc-shaped basic body of thickness d. The collar 39 is thereby formed so that at its the central passage opening 32 bounding inner surface 41st a spherical geometry is formed, which corresponds to the ball geometry 42, which is shown schematically and corresponds to the outer contour of the anvil 29. The collar 39 is formed from the body of the retraction plate 24 so as to extend from a first surface 34 having an axial directional component from the first surface 34.

In addition, the guide collar 38 is already formed on the retraction plate 24 shown in FIG. 2a, through which the Gleitschuhaufnahmeöffnungen 36 are completely closed. The guide collars 38 extend in an opposite direction to the collar 39, so that the guide collars 38 also extend from a second surface 40 of the retraction plate 24 with an axial directional component. The forming of the formed as a flat disc base body is preferably carried out in a single step simultaneously with the punching of the central passage opening 32 and the Gleitschuhaufnahmeöffnungen 36. By embossing the central passage opening 32 and the Gleitschuhaufnahmeöffnungen 36 bounding edges of the body to the collar 39 and the guide collar 38, a solidification of the material of the retraction plate 24 is also achieved. Thus, the thickness d of the material of the base body can be reduced again without getting problems with durability during operation of the axial piston machine 1.

Fig. 2b shows a finished retraction plate 24. In contrast to the retraction plate 24 shown in Fig. 2a was in the in.Fig. 2b illustrated retraction plate 24, the first surface 34 processed so that a flat first surface 34 'is formed, which surrounds the collar 39 in the radial direction on the outside. In the processing of the first surface 34 to the flat first surface 34 'is thereby removed just as much material that the height of the guide collar 38 together with the material thickness d to an overall height H of the Gleitschuhaufnahmeöffnung 36th complete. The deformation height h of the guide collar 38 is preferably between 50% and 75% of the thickness d of the main body. Particularly preferably, the forming height h is chosen so that its share in the total height H is about 40%.

FIG. 3a shows a detail IIIa from FIG. 2a in an enlarged view. In this case, both the first surface 34 and a machining allowance 49 is shown, which is indicated by the dashed line. The Gleitschuhaufnahmeöffnung 36 has an inner surface 43 which has the shape of a cylinder jacket surface. When forming the guide collar 38, the base body is reshaped so that the inner surface 43 in the axial direction has the shape of a cylinder jacket surface, wherein the height of the cylinder jacket surface extends over a substantial part of the functional height. The cylindrical surface is produced directly by the stamping process, without the need for a subsequent machining.

In the inner surface 41 of the central passage opening 32, a region 41 'is provided in addition to the spherical portion, which has the shape of the lateral surface of a truncated cone. The region 41 'is that part of the inner surface 41 of the collar 39, which is furthest away from the first surface 34.

In Fig. 3b the section IIIb of Fig. 2b is shown enlarged. As already explained with reference to FIG. 2 b, the flat first surface 34 'is produced by means of machining on the retraction plate 24. In order to allow greater freedom of movement of the sliding blocks 12 in the radial direction, an undercut 47 is provided at a transition between the collar 39 and the flat first surface 34 '. During the machining of the flat first surface 34 ', a radius 46 is worked out at the transition between the planar first surface 34' and the inner surface 43. It will that portion of the inner surface 43 which deviates from the shape of a cylinder jacket surface by the radius 46 is kept small in comparison to the overall height H. With an overall height H of, for example, about 5.5 mm, the radius 46 is preferably only about 0.6 mm. More generally, it can be stated that the radius 46 preferably occupies a portion of the guide height H of less than 15%.

As has already been stated above, the inner surface 41 of the central passage opening 32 has a region 41 'which has the shape of a conical jacket. A portion of this portion 41 'is cured, preferably using a laser process to cure a narrow portion 48. The heat input during laser hardening is limited locally and the occurring material distortion is negligible. A subsequent machining is therefore not required.

In Fig. 4 is a plan view of the retraction plate 24 according to the invention from the side of the guide collar 38 is shown. In the illustrated embodiment, the retraction plate 24 is made of a circular disk as a base body, so that the retraction plate 24 has a circular outer contour 50. The central passage opening 32 is introduced into the retraction plate 24 concentrically with the circular outer contour 50. The Gleitschuhaufnahmeöffnungen 36 are arranged on a circumferential circle 51, which is also arranged concentrically to the outer contour 50 of the retraction plate 24. In the illustrated embodiment, nine Gleitschuhaufnahmeöffnungen 36 are arranged uniformly distributed along the circumferential circle 51.

The diameter of the circular outer contour 50 is selected so that the guide collar 38 are completely closed around the Gleitschuhaufnahmeöffnungen 36. The guide collars 38 are also surrounded by an outer portion 52 which encloses all the guide collar 38 as a closed circular disc. Between Guide collar 38 adjacent Gleitschuhaufnahmeöffnungen 36 are disc elements 53 formed with the thickness d of the body, through which the retraction plate 24 reaches a high degree of rigidity.

In Fig. 5, an example of a retraction plate 24 is shown again as a perspective view.

In the most favorable case, the retraction plate can also be used without aftertreatment of the contact surface with the sliding shoes.

Instead of using the retraction plate 24 according to the invention in the axial piston machine 1 in a swash plate design, the use is also possible in axial piston machines in swash plate design or bent axis design.

Claims (28)

1. Recoil plate for an axial piston machine, wherein the recoil plate (24) is disk-shaped and has a central through-opening (32), which is encircled by a collar (39), which extends with an axial direction component from a first surface (34, 34') of the recoil plate (24), and wherein the recoil plate (24) has a plurality of sliding-shoe-receiving openings (36),
   characterized in
   that the sliding-shoe-receiving openings (36) are encircled in each case by a guide collar (38), which extends with an axial direction component from a second surface (40) of the recoil plate (24) in the opposite direction to the collar (39) of the central through-opening (32).
2. Recoil plate according to claim 1,
   characterized in
   that at least a portion of an inner face (43) of the guide collar (38) that in each case delimits the sliding-shoe-receiving opening (36) has the shape of a cylinder lateral surface.
3. Recoil plate according to claim 2,
   characterized in
   that the height of the cylinder lateral surface is a substantial fraction of an overall height (H) of the sliding-shoe-receiving opening (36).
4. Recoil plate according to one of claims 1 to 3,
   characterized in
   that the first surface (34, 34') of the recoil plate (24) in a region, which surrounds the collar (39) in radial direction at the outside, is a flat surface.
5. Recoil plate according to one of claims 1 to 4,
   characterized in
   that the sliding-shoe-receiving openings (36) are completely encircled by a radially outer region (52) of the recoil plate (24).
6. Recoil plate according to claim 5,
   characterized in
   that the radially outer region (52) of the recoil plate (24) has a circular external contour (50).
7. Recoil plate according to one of claims 1 to 6,
   characterized in
   that a portion of an inner face (41) of the collar (39) that delimits the central through-opening (32) in radial direction has a spherical shape.
8. Recoil plate according to one of claims 1 to 7,
   characterized in
   that at least one portion (41') of the inner face (41) of the collar that delimits the central through-opening (32) is hardened.
9. Recoil plate according to one of claims 1 to 8,
   characterized in
   that the collar (39) and the guide collars (38) are formed by shaping a flat basic body.
10. Recoil plate according to claim 9,
    characterized in
    that the basic body is a circular disk.
11. Recoil plate according to one of claims 1 to 10,
    characterized in
    that the collar (39) and the oppositely directed guide collars (38) are formed in a punching/embossing process.
12. Axial piston machine comprising a cylinder drum (4), which rotates relative to a running surface (28), which is arranged inclined relative thereto and on which sliding shoes (12) are supported by a sliding face (25) in order to generate a reciprocating motion of pistons (10), which are axially displaceable in cylinder bores (9) of the cylinder drum (4), wherein the sliding shoes (12) during an induction stroke are held by means of a recoil plate (24) in abutment on the running face (28) and the recoil plate (24) for receiving the sliding shoes (12) has sliding-shoe-receiving openings (36), in each case a retaining face (33) of the sliding shoe (12) that is oriented in the opposite direction to the sliding face (25) of the sliding shoes (12) abuts on a first surface (34) of the recoil plate (24) and the recoil plate (24) is supported by an inner face (41) of a collar (39) that encircles a central through-opening (32) against a thrust bearing (29) and the collar (39) extends with an axial direction component from the first surface (34),
    characterized in
    that the sliding-shoe-receiving openings (36) are encircled in each case by a guide collar (38), which extends with an axial direction component from a second surface (40) of the recoil plate (24) in the opposite direction to the collar (39) of the central through-opening (32).
13. Axial piston machine according to claim 12,
    characterized in
    that at least a portion of an inner face (43) of the guide collar (38) that in each case delimits the sliding-shoe-receiving opening (36) has the shape of a cylinder lateral surface.
14. Axial piston machine according to claim 13,
    characterized in
    that the height of the cylinder lateral surface is a substantial fraction of an overall height (H) of the sliding-shoe-receiving opening (36).
15. Axial piston machine according to one of claims 12 to 14,
    characterized in
    that the first surface (34, 34') of the recoil plate (24) in a region, which surrounds the collar (39) in radial direction at the outside, is a flat surface (34').
16. Axial piston machine according to one of claims 12 to 15,
    characterized in
    that the sliding-shoe-receiving openings (36) are completely encircled by a radially outer region (52) of the recoil plate (24).
17. Axial piston machine according to claim 16,
    characterized in
    that the radially outer region (52) of the recoil plate (24) has a circular external contour (50).
18. Axial piston machine according to one of claims 12 to 17,
    characterized in
    that a portion of an inner face (41) of the collar (39) that delimits the central through-opening (32) in radial direction has a spherical shape.
19. Axial piston machine according to one of claims 12 to 18,
    characterized in
    that at least a portion (41') of the inner face (41) of the collar (39) that delimits the central through-opening (32) is hardened.
20. Axial piston machine according to one of claims 12 to 19,
    characterized in
    that the collar (39) and the guide collars (38) are formed by shaping a flat basic body.
21. Axial piston machine according to claim 20,
    characterized in
    that the basic body is a circular disk.
22. Axial piston machine according to one of claims 12 to 21,
    characterized in
    that the collar (39) and the oppositely directed guide collars (38) are formed in a punching/embossing process.
23. Method of manufacturing a recoil plate (24) for an axial piston machine (1) comprising the following method steps:

    - manufacture a disk-shaped basic body;

    - punch sliding-shoe-receiving openings (36);

    - punch a central through-opening (32);

    - shape an inner edge of the disk-shaped basic body that delimits the central through-opening (32) into a collar (39) such that the collar (39) extends with an axial direction component from a first surface (34) of the recoil plate (24); and

    - shape an edge of the disk-shaped basic body that in each case delimits the sliding-shoe-receiving openings (36) into in each case a guide collar (38) such that the guide collars (38) extend with an axial direction component from a second surface (40) of the recoil plate (24).
24. Method according to claim 23,
    characterized in
    that at least one portion (41') of an inner face (41) of the collar (39) is hardened.
25. Method according to claim 24,
    characterized in
    that the portion (41') of the inner face (41) is hardened with the aid of a laser.
26. Method according to one of claims 23 to 25,
    characterized in
    that the edges of the sliding-shoe-receiving openings (36) and the inner edge of the central through-opening (32) are formed into the guide collars (38) and the collar (39) in a common embossing process.
27. Method according to claim 26,
    characterized in
    that punching-out of the central through-opening (32) and of the sliding-shoe-receiving openings (36) and forming of the edges is carried out in a single operation in a punching/embossing process.
28. Method according to one of claims 23 to 27,
    characterized in
    that the first surface (34) of the disk-shaped basic body remote from the guide collars (38) is, after forming, machined in respect of its flatness and surface quality.

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