EP0785359B1 - Weight optimisation for a piston shoe - Google Patents

Description

The invention relates to a sliding shoe for use in an axial or radial piston machine.

A multi-part designed shoe after Preamble of claim 1 for use in hydrostatic machinery is disclosed in US 5,392,693A described. This known shoe consists of a support member and one inserted therein step cylindrical sliding part, the larger one Cylinder stage forms a flange from a Retaining device is engaged, which in the Functional operation a lifting of the shoe from the associated swashplate prevented. The support body is placed in a cap shape on the smaller cylinder step. The support part has a spherical recess in the Ring part surrounding ring part, which at the 3 to 5 for the positive rear grip of the spherical head associated piston is deformed radially inward.

From DE 36 27 652 A1 a two-part sliding shoe with a sliding layer adjacent to the sliding surface a ceramic material and a support body from one take hardened bearing steel. By at the Sliding sole arranged ceramic layer is said to be one Seizure of the sliding shoes can be counteracted.

From US 3,263,623 A is also a two-part Known sliding shoe. The ring-shaped sliding part is arranged so that it with a pressure pocket hydraulic relief of the sliding block not in Touch. This will result in leakage counteracted, which can arise if the porous Material of the sliding part in connection with the pressure pocket would.

At high speeds of hydrostatic machines the sliding shoes are subjected to considerable centrifugal forces. These cause the slide shoes to tip, resulting in a Damage to the slide shoes and / or to the inclined or Swash plate trained sliding surface leads.

There is, therefore, a requirement on the sliding shoes to reduce centrifugal forces and centrifugal masses and thus a higher speed range when operating the to enable hydrostatic machine.

The design that can be found in US Pat. No. 5,392,693 A is located based on the knowledge that to reduce the Centrifugal force acting on the sliding blocks the dead weight of the Slip shoes must be reduced. This will be achieved that the shoe in a support body and a is subdivided into this inserted sliding part and for the sliding part a material with good Sliding properties with low specific Weight and a high material for the support body mechanical strength at the same time low specific weight is selected. A Targeted material selection is through the two-part Subdivision of the slide shoe allows, because for that Sliding part in addition to low specific weight only for good sliding properties, but not for that mechanical strength must be respected, whereas for the support body in addition to low specific weight in essential to a high mechanical strength pay attention while the sliding properties of this Material are irrelevant.

The invention is based, with one Sliding shoe of the type specified initially supports the To improve sliding part.

This object is achieved by the features of claim 1 solved. Advantageous developments of the invention are in described the subclaims.

In the slide shoe according to the invention, the support body has a flange at its end facing the sliding sole on, in which a step extension of the insert hole is arranged, the second cylinder section in the Bordered step recess. Here, the sliding part is in Shape of a stepped cylinder with sections different diameter, the at a recess for receiving the ball head of the assigned piston adjacent section to the Diameter of this recess can be adjusted. there the ball head of the piston transfers the supporting force directly on the sliding part, which is on the outside of the Support body is surrounded.

Claims 2 to 4 relate to an advantageous Material selection for the support body and the sliding part. The Support body is preferably made of aluminum or one Aluminum alloy. Light metals are particularly suitable Titanium or a titanium alloy.

The sliding part is preferably made of a ceramic material. All materials that can be used as bearings are particularly suitable, such as Al ₂ O ₃ , ZrO ₂ , SiC and Si ₃ N ₄ .

An articulated connection between the shoe and one associated pistons can be designed in a simple manner, if according to claim 5 facing away from the sliding sole End region of the sliding block of the support body, the sliding part surmounted.

The sliding part can be supported on the supporting part further improve if according to claim 6, the diameter of the first cylinder section with the diameter of the Recess for receiving the ball head essentially matches.

According to claim 7, the sliding part of one Lubrication hole must be penetrated.

It is for the hydrostatic relief of the glide shoe advantageous, one in the sliding sole of the sliding part Arrange pressure pocket into which the lubrication hole opens.

Fig. 1

einen Schnitt durch ein erstes Ausführungsbeispiel eines Gleitschuhs;

Fig. 2

einen Schnitt durch ein zweites Ausführungsbeispiel eines Gleitschuhs;

Fig. 3

einen Schnitt durch ein drittes Ausführungsbeispiel eines erfindungsgemäßen Gleitschuhs;

Fig. 4

eine Draufsicht auf die Gleitsohle eines Gleitschuhs entsprechend einem der Ausführungsbeispiele der Figuren 1 bis 3;

Fig. 5

einen Schnitt durch eine Axialkolbenmaschine;

Fig. 6

einen Schnitt durch einen Gleitschuh mit zugehörigem Kolben, wobei der Kugelkopf am Kolben ausgebildet ist;

Fig. 7

einen Schnitt durch einen Gleitschuh mit zugehörigem Kolben, wobei der Kugelkopf am Gleitschuh ausgebildet ist;

Fig. 8

einen Schnitt durch einen Gleitschuh in abgewandelter Ausgestaltung.

Various exemplary embodiments of sliding shoes are described below with reference to the drawings. In it show:

Fig. 1

a section through a first embodiment of a sliding shoe;

Fig. 2

a section through a second embodiment of a sliding block;

Fig. 3

a section through a third embodiment of a sliding block according to the invention;

Fig. 4

a plan view of the sliding sole of a sliding shoe according to one of the embodiments of Figures 1 to 3;

Fig. 5

a section through an axial piston machine;

Fig. 6

a section through a sliding block with associated piston, the ball head being formed on the piston;

Fig. 7

a section through a slide shoe with associated piston, the ball head being formed on the slide shoe;

Fig. 8

a section through a sliding block in a modified design.

In the axial piston machine 1 shown schematically in FIG Cylinder drum 3 non-positively connected to a rotatably mounted shaft 2. In the Cylinder drum 3 are radially evenly distributed cylinder bores, hereinafter referred to as Designated cylinder 4, arranged. Pistons 5, 6 are displaceable in the cylinders 4 stored, the piston heads 7, 8 on the sliding surface 20 of a fixed Support swash plate 9 over sliding shoes 10, 11. The cylinders 4 are over Connection openings 12a, 12b and the control openings 14, 15 with a control plate 16 the pressure lines 17 and 18 connected.

The invention relates to a development of the sliding shoes 10, 11. However, the invention not limited to use with axial piston machines and is equally suitable Way of use in connection with radial piston machines.

Figures 1 to 3 show different embodiments of the Sliding shoes 10. All of the exemplary embodiments have in common that the sliding block 10 in a support body 30 and an inserted in the support body 30 and with this connected sliding part 31 is divided. While the sliding part 31 on the adjacent sliding surface 20 e.g. sliding, swashplate or swashplate is present, the connection with the associated piston (5 in Figure 5) made. For this purpose, the support body 30 in the illustrated in Figures 1 to 3 Embodiments an at least partially spherical recess 32 in which the spherical piston head (7 in Figure 5) can be inserted. On the The connection between the piston and the support body is exactly based on FIGS. 6 and 7 received.

The sliding block has on its underside sliding sole 35 for hydrostatic relief a pressure pocket 34 which, via a lubrication hole 33 with the recess 32 in Connection is established. With regard to the exact geometry of the recess 32 and Lubrication bore 33, in particular in the region of the mouth of the lubrication bore 33 in the recess 32 and in the pressure pocket 34 is on the utility model DE-Gbm 295 14 831.4 by the same applicant, the disclosure of which in the present Registration to shorten the presentation is included by reference.

The subdivision of the sliding block 10 into a sliding part 31 is essential to the invention a material with good sliding properties and a support body 30 made of one material high mechanical strength. Since only the material for the sliding part 31 Sliding properties, but not the requirements for mechanical strength in the The foreground and vice versa for the material of the support body are mechanical Strength with respect to tensile and bending stress is essential Sliding properties are insignificant due to the lack of contact with the sliding surface 20, This creates greater scope for the targeted selection of suitable materials low specific weight. Both for the sliding part, but especially for the Support bodies can use materials that are opposite one conventional glide shoes have a significantly lower weight. Thereby the weight of the entire sliding shoe 10 can be significantly reduced overall, which causes a reduction in the centrifugal force acting on the sliding block 10. By the separation according to the invention of the sliding and supporting function of the sliding shoe Subdivision into a sliding part 31 and a support body 30 can therefore the speed of a hydrostatic machine in which the slide shoes according to the invention are used come, be increased significantly without the risk of damage to the sliding shoes and / or the sliding surface of the swashplate, swashplate or slant plate.

Light metals, in particular made of aluminum, are particularly suitable for the support body 30 or an aluminum alloy. AL Zu Mg Cu 1.5%, Ti A16V4 are particularly suitable.

Ceramic materials, in particular Al ₂ O ₃ , ZrO ₂ , SiC and Si ₃ N ₄ , are particularly suitable for the sliding part 31. However, a lead-bronze alloy and other plain bearing materials can also be considered.

With regard to the shape of the sliding part 31, there are different ones in FIGS. 1 to 3 Exemplary embodiments shown. In Figure 1, the sliding part 31 is annular, while the sliding part 31 in Figure 2 has a disc-shaped shape and of the Lubrication hole 33 is penetrated centrally.

In FIG. 3, however, the sliding part 31 is designed in the form of a stepped cylinder, which is into a first cylinder section 31a adjoining the recess 32 and one second cylinder section 31b forming the sliding sole 35. The first Cylinder section 31a forms the lower end of the recess 32 and is in this Area shaped in the same way as the support body 30 in the exemplary embodiments 1 and 2. The second cylinder section 31b adjoins the sliding surface 20 of the Swashplate, swashplate or swashplate and takes up the pressure pocket 34. Furthermore, in In this embodiment, the lubrication hole 33 is completely in the sliding part 31 educated.

The embodiment shown in Figure 3 has the advantage that the supporting force of the spherical cylinder head 7 of the piston 5 directly onto the sliding part 31 is transmitted and thus stresses at the interface between the support body 30 and the sliding part 31 can be avoided. The support body 30 surrounding the sliding part 31 but absorbs the outward forces, which is essential if the sliding part 31 from a brittle material, in particular from a Ceramic material.

Figure 4 shows the exemplary design of the sliding sole 35 of an inventive Slide shoe according to one of those shown in Figures 1 to 3 Embodiments. You can see the mouth of the lubrication hole 33, which in the Pressure pocket 34 opens. The pressure pocket 34 can be one or more Subdivisions 36 can be divided like a labyrinth in order to ensure the rapid escape of the Counteract pressure medium and thus improve the hydrostatic relief.

Figures 6 and 7 show two embodiments of an articulated connection between the slide shoe 10 according to the invention and the associated piston 5.

In the embodiment according to FIG. 6, a ball head 40 is attached to the piston 5 formed, which engages in the spherical recess 41 of the shoe 10. The Ball head connection 40, 41 enables within a predetermined angular range a free angle adjustment of the slide shoe 10 with respect to the longitudinal axis 43 of the piston.

In the exemplary embodiment according to FIG. 7, on the other hand, there is a ball head 44 on the sliding block 10 molded on, while the piston 5 has a spherical recess 45. To this Way is also an articulated connection between the shoe 10 and the Piston 5 realized.

For reasons of weight, the piston 5 is designed as a hollow piston. The cylinder side The open piston cavity 46 is on the sliding shoe side through a lubricant channel 47 extended. The funnel-shaped mouth areas 48 and 49 of the lubrication hole 33 or the lubricant channel 47 overlap in each angular position that the Sliding shoe 10 can take against the longitudinal axis 43 of the piston 5, so that in a continuous flow of lubricant from piston cavity 46 at each angular position to the pressure pocket 34 shown in FIGS. 1 to 4.

The present invention is not limited to the exemplary embodiments shown. Rather, there are various geometric shapes used in the support body 30 Sliding part 31 possible. It is also conceivable that the sliding part 31 in turn has several parts trained, e.g. through several sliding blocks arranged on a circular line.

8, with the same or comparable parts with are provided with the same reference numerals, is on the sliding sole 35 of the sliding block 10 Sliding layer 51 made of a material with good sliding properties and preferably also arranged a low specific weight.

Another sliding layer 52 is located on at least part or all of it spherical articular surface 53, which is concave in the embodiment according to FIG. 8 is formed and forms the recess 32, but also convex on a ball head 44 7 can be formed.

8, the recess 32 extends surrounding ring wall 54 of the support body 30 and the arranged on the inner surface spherical joint surface 53 with the sliding layer 52 over the center of the spherical shape out to the side facing away from the sliding sole 35 so far that the ball head 40 of the associated pistons 5, 6 is engaged on the one hand and on the other the Joint mobility of the joint connection is guaranteed. It can also do this the sliding layer 52 or a corresponding thicker sliding part in the recess 32 be held positively. The spherical joint surface 53 thus has one spherical shape. This also applies to the sliding layer 52, whereby this is on the side facing away from the sliding sole 35 up to the free edge of the spherical Joint surface 53 may extend or may have an axial distance therefrom. The Lubrication hole 33 also passes through sliding layer 52.

In such cases, in which the sliding shoe 30 has the sliding sole 35 on it Side one of the annular wall 57 radially projecting flange 55 with one to the Stepped surface 56 facing away from the sliding sole 35 for an arrow has indicated hold-down 57, it is advantageous to the preferred a step surface 56 extending at right angles to the longitudinal central axis of the sliding block 30 Sliding layer 58 made of a material with good sliding properties and preferably also low specific weight. The sliding layer can also be attached to the Step surface 56 adjoining cylindrical peripheral wall portion of the ring wall 54 as Sliding layer 58a can be arranged.

The coating material of the sliding layer 51 and / or 52 and / or 58 or 58a has in addition to the necessary adhesion to the base material of the support body 30 still sufficient Sliding properties as well as abrasion resistance and preferably also a low specific one Show weight. Because the aforementioned sliding layer or sliding layers in comparison with an inserted sliding part 31 according to the previously described exemplary embodiments has a smaller volume, plays the specific weight of the sliding layer or Sliding layers according to FIG. 8 are of less importance, and therefore they can Sliding layers in the context of the invention consist of a light material, e.g. out a ceramic material of the types already described, or from a material usual larger specific weight, as is the case with conventional sliding materials, e.g. Metals with sliding properties, is common. Serve in the embodiment of FIG. 8 the overlay or overlay essentially increases the magnification of the Wear resistance and the lifespan of the sliding block 30, which is also used for Weight reduction and thus to improve the dynamic properties contribute if at the same time made of a material of low specific weight consist.

It is possible and advantageous within the scope of the invention, also the sliding layer or Sliding layers 51, 52, 58, 58a according to FIG. 8 as inserted in the support body 30 To design sliding parts. In such cases or even if the sliding layers are a greater thickness than e.g. have about 0.3 to 0.5 mm, it is particularly advantageous to a Use material of lower specific weight because in these cases the Volume proportion with respect to the volume of the support body 30 is larger and thus for Weight reduction of the shoe 10 can be contributed. With thicker ones Therefore, the respective sliding layer 51, 52, 58, 58a forms a sliding sheet, and 8 is therefore also designated by the reference number 31 in FIG. In addition, such sliding parts 31 can also be used in recesses 58b, as is the case Fig. 8 shows.

8, the convergent shape of the ring wall 54 is after the insertion of the associated ball head 40 into the recess 32 by bending or indentation is produced, the ring wall 54 being permanently deformed. So that associated sliding layer 52 or a corresponding sliding part participate in this deformation In such a case, it is advantageous to use a material that corresponds is deformable or bendable.

In the exemplary embodiment according to FIG. 8, the pressure pocket 34 can be replaced by one or several subdivisions 36 can be divided like a labyrinth in order to ensure the rapid escape of the Counteract pressure medium and thus improve the hydrostatic relief.

As can be seen from Fig. 8, the sliding layer 51 is also on the Base area of the pressure pocket 34. This is the case in the present exemplary embodiment given that the sliding layer 51 is applied by a coating process, where not only the sliding sole surface, but also the base surfaces of the Subdivisions 36 are co-coated, which is easier in this case than another Measure to cover subdivisions 36. With such a coating also the Base area of the pressure pocket 34 also passes through the lubrication bore 32 Coating as shown in Fig. 8.

Claims (8)

1. a) Shoe (10) for slidably supporting the pistons (5, 6) of an axial or radial piston engine against a slide face (20),

   b) consisting of a supporting body (30), communicating with the assigned piston (5),

   c) which has an insertion hole going through in the axial direction,

   d) is inserted into the one sliding part (31),

   e) which is connected to the supporting body (30),

   f) and at a front end has a sliding base (35) for sliding contact on the slide face (20),

   g) whereby the sliding part (31) consists of a material with good sliding properties and at the same time low specific weight,

   h) whereby the supporting body (30) consists of a material with high mechanical strength and at the same time low specific weight,

   i) whereby the sliding part (31) is designed in the form of a stepped cylinder,

   j) with a first cylinder section (31a), which faces away from the sliding base (35) and in its front area has at least a partially spherical recess (32) for the piston (5, 6),

   k) and with an enlarged second cylinder section (31b) in comparison to the first cylinder section (31a), which forms the sliding base (35), characterized in that

   l) the supporting body (30) at its end facing the sliding base (35) has a flange,

   m) in which a stepped extension of the insertion hole is arranged,

   n) and in that the second cylinder section (31b) fits into the stepped recess.
2. Shoe according to claim 1, characterized in that the supporting body (30) is made of light metal, in particular aluminum or an aluminum alloy and/or titanium or titanium alloy.
3. Shoe according to claim 1 or 2, characterized in that the sliding part (31) consists of a ceramic material.
4. Shoe according to claim 3, characterized in that the ceramic material concerned is Al₂O₃, ZrO₂, SiC.
5. Shoe according to any one of the previous claims, characterized in that the supporting body (30) juts out over the sliding part (31) in the end area of the shoe (C) facing away from the sliding base (35).
6. Shoe according to claim 5, characterized in that the diameter of the first cylinder section (31a) essentially matches the diameter of the recess (31) for engaging the spherical head (40).
7. Shoe according to any one of the previous claims, characterized in that the sliding part (31) is penetrated by a lubricating bore (33).
8. Shoe according to claim 7, characterized in that a pressure pocket (34), into which the lubricating bore (33) opens, is arranged in the sliding base (35).

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