WO2007028469A1

WO2007028469A1 - Swash-plate pivot bearing

Info

Publication number: WO2007028469A1
Application number: PCT/EP2006/007727
Authority: WO
Inventors: Klaus Becker; Harald Vornehm
Original assignee: Schaeffler Kg
Priority date: 2005-09-10
Filing date: 2006-08-04
Publication date: 2007-03-15
Also published as: DE102005043032A1

Abstract

A swash-plate pivot bearing comprises - a hollow-cylindrical outer bearing surface (2), which is formed by a bearing ring (1) which is produced from a curved metal strip and is intended for a swash plate (12), the bearing surface (2) being bounded axially at least on one side by a rim (5, 6) which extends radially inwards and is formed integrally from the bearing ring (1), - a cylindrical inner bearing surface (13) for the swash plate (12), - a curved cage (14), which is arranged between the bearing surfaces (2, 13) and has a number of pockets (16), - and a number of rolling-contact bodies (15) arranged in the pockets (16), a plurality of rolling-contact bodies (15) being arranged axially one beside the other in each pocket (16).

Description

Name of the invention

Swash plate pivot bearings

description

Field of the invention

The invention relates to a swash plate pivot bearing, in particular for a hydraulic axial piston machine, in which between a hollow cylindrical bearing surface for the swash plate and a cylindrical bearing surface of the swash plate rolling elements are arranged.

Background of the invention

A swash plate pivot bearing for a hydraulic axial piston machine is known for example from DE 25 21 312 B1, wherein it may be a hydraulic motor or a hydraulic pump in the axial piston machine. In any case, the stroke volume is adjustable by the swash plate. By prevailing in the piston of the motor or the pump pressure of the hydraulic fluid considerable forces are introduced into the swash plate pivot bearing.

Summary of the invention

The invention has for its object to provide a swashplate pivot bearing, in particular for hydraulic pumps and motors, which has a particularly low dependence of the mechanical properties of the load condition. This object is achieved by a swash plate pivot bearing with the features of claim 1. This pivot bearing, which is suitable for a hydraulic motor as well as for a hydraulic pump, has a substantially arcuate bearing ring, which provided for the storage of the swash plate bearing surface axially is bounded at least on one side by a radially inwardly extending, integrally formed from the bearing ring board, also referred to as a skirt. Rolling elements which also contact a cylindrical inner bearing surface of the swashplate are arranged on the bearing surface of the bearing ring produced from a bent metal strip. The leadership of the rolling elements is arranged between the hollow cylindrical outer bearing surface of the bearing ring and the inner bearing surface of the swash plate curved cage with a number of pockets, wherein in the individual pockets each have a plurality of rolling elements are arranged axially adjacent.

The swash plate pivot bearing according to claim 1 has numerous advantages over the prior art: The limitation of the bearing surface of the bearing ring by one, preferably two, normal to the bearing surface inwardly extending edge strip - or edge strips - favors a precise guidance of the rolling elements. Preferably, the transition between the tread and the or each edge strip is designed such that a first side of a rectangular in cross-section body can completely abut the bearing surface and a second side completely on the edge strip. In other words, any fillet present between the bearing surface and the edge strip is designed such that it does not restrict the available installation space for the rolling bodies. Such recesses, also referred to as reliefs, on the ribs of the bearing ring ensure that the entire width between the edge strips for the rolling elements, even if they are not rounded at the transition to the end faces, is available. The use of cylindrical Wälzkörpem without significant edge rounding allows for a cost-effective production and allows the other a construction of the swash plate pivot bearing a particularly favorable relation between dimensions and mechanical load capacity.

When occurring during operation loads of swash plate pivot bearing at least slight deflections of components can not be avoided. In order to avoid that consequently rolling elements do not rest optimally on the bearing surfaces, in each case a plurality of rolling elements are guided in the individual pockets of the arranged between the bearing surfaces arcuate cage whose end faces are immediately adjacent to each other. It is thus possible that the axes of different rolling elements arranged in a pocket do not completely coincide depending on the load condition of the swash plate pivot bearing. Further, it is possible that within a pocket different rolling elements rotate with at least minimally different speed. Preferably, at least three disk-shaped rolling bodies are located in each pocket of the cage. The diameter of each rolling element is preferably greater than its height, i. its dimension in the axial direction. The cage forming the pockets for the rolling elements can be produced, as is known in principle from roller bearing technology, from a polymer material, in particular a fiber-reinforced plastic.

According to an advantageous development, the cage has a projecting in the axial direction beyond the bearing ring out support pin. Such a support pin in a swash plate pivot bearing is known in principle, for example from DE 199 25 834 A1. As described herein, it is advantageous to at least partially encase the support pin with metal. According to a further embodiment, which can be combined with a metal casing of the support pin, the support pin has a bearing on which a control guide lever is pivotally mounted. The control lever can serve both for control purposes and facilitate the installation of the swash plate pivot bearing. Particularly favorable storage properties are given when the at least one board of the bearing ring has a height measured in the radial direction, of the square root of the product of the wall thickness of the bearing ring on the outer bearing surface and the diameter of the rolling elements by not more than 25%, in particular not more than 15%, deviates. With this relation between different dimensions of the bearing ring and the rolling elements is a so-called carpet effect, that is, an inadmissible deformation of the tread in the manner of sliding together a carpet under heavy loaded loads, avoided.

According to a further advantageous embodiment, the bearing ring has a curvature in such a way that it is bent slightly outwards in the edge region, that is to say in the region of the ribs, if ribs are present on both sides. If the bearing ring is supported by a component with a smooth, cylindrical surface, then the region of the bearing ring which lies between the ribs is lifted slightly away from the component, resulting in elastic resilience.

Several embodiments of the invention will be explained in more detail with reference to a drawing.

Brief description of the drawings

Show it:

1 and 2 a bearing ring for a swash plate

Pivot bearings in various overall and detail views,

FIGS. 3 and 4 show various embodiments of a swashplate pivot bearing, Figures 5 and 6 in cross sections different bearing rings for a

Swash plate pivot bearing,

FIG. 7 shows a rolling element arrangement for a swash plate

Swivel bearing according to Figure 3 or 4 in comparison with a conventional rolling element assembly.

Detailed description of the drawings

Figures 1 and 2 show a bearing ring 1 for a not shown here swash plate pivot bearing a hydraulic axial piston machine, ie a hydraulic motor or a hydraulic pump. The bearing ring 1 is made as a bent metal strip and has a hollow cylindrical outer bearing surface 2 for supporting a swash plate. An axis A indicates the axial direction of the bearing ring 1 and the entire swash plate pivot bearing. On the longitudinal sides 3, 4 of the bearing surface 2 are radially inwardly directed edge strips 5, 6, also referred to as rims, at. The two edge strips 5, 6 have the same shape, so that the bearing ring 1 as a whole is symmetrical with respect to a normal to the axis A arranged in the middle plane E. The symmetrical shape of the bearing ring 1 has the particular advantage that a delay in curing is avoided. The bearing ring 1 can be case-hardened and tempered or hardened and tempered after molding.

The detail X in Fig. 1 shows the transition between an outer bearing surface 2 forming arc section 7 and a flat, in the illustrated embodiment very short end 8 of the bearing ring 1. Between said sections 7, 8 of the bearing ring 1 is a hollow Eckausrundung 9 is formed so that the corner stays clear. Similarly, the transition between the bearing surface 2 and the lateral edge strips 5, 6 in each case also has a corner fillet 10 (see Fig. 2), also referred to as an exemption. The exemption cause lungs 10 that in the transition areas between the bearing surface 2 and the edge strips 5, 6 during operation of the swash plate pivot bearing no forces are introduced in an undefined manner in the bearing ring 1. Next, the given cross-sectional geometry of the bearing ring 1 has the advantage that the entire inner bearing ring width L, which is formed between the edge strips 5, 6, for cylindrical rolling elements, even without significant edge rounding, is available. The symmetrical design of the edge strips 5, 6 allows a simple way a precise axial guidance of the rolling elements. Overall, the bearing ring 1 is mounted in a housing, not shown, of the axial piston machine with an adjustable stroke volume.

In Fig. 2, the bearing ring 1 with the exception of the right in the illustration cross-section in unfinished state, namely with not yet bent shelves 5,6, shown. The wall thickness of the shelves 5, 6 is reduced in comparison to the wall thickness in the region of the bearing surface 2, as can be seen in particular from the cross section shown on the left in FIG. 2. This allows in a very simple manner a formation of the exemptions 10 when bending the shelves 5,6.

In Figure 3 is a fragmentary view of a first embodiment of a swash plate pivot bearing 11 is shown, which in addition to the bearing ring 1 also referred to as a swivel plate swash plate 12 with a cylindrical inner bearing surface 13, a cage 14 and a number of rolling elements 15 includes. In this case, a plurality of cylindrical rolling elements 15 are arranged one behind the other in the axial direction in individual pockets 16 of the arcuate cage 14 made of a polymer material in FIG. The cage height K measured in the radial direction of the swashplate pivot bearing 11 fills the gap height S between the inner bearing surface 13 and the outer bearing surface 2 by more than 60%, in particular more than 80%. This allows a particularly accurate axially parallel guidance of the individual rolling bodies 15. In the middle of the arcuate cage 14, the latter has a supporting pin 17 projecting in the axial direction over the bearing ring 1, the part of a tracking device of the cage 14 is. The support pin 17 is enclosed over a part of its length by a metal ring 18, which increases the stability of the Stϋtzzapfens 17 and its life.

The embodiment of Figure 4 differs from the embodiment of Figure 3 mainly characterized in that the metal ring 18 is a positive connection with the plastic material of the support pin 17, which is integrally formed in this case integrally with the cage 14 has.

FIGS. 5 and 6 show possible configurations of the cross section of the bearing ring 1, wherein the cross-sectional shape according to FIG. 5 corresponds in principle to the exemplary embodiment according to FIGS. 1 and 2. Thereafter, the bearing ring 1 in the region of the bearing surface 2 has a wall thickness d of, for example, 2.95 mm. The height h of the shelves 5, 6 measured in the radial direction of the swash plate pivot bearing 11 is 4.3 mm in the case of a rolling element diameter of 5 mm, for example. With a rolling element diameter increased by 1 mm, higher edges 5, 6 are required by 0.2 mm. With a rolling element diameter of 10 mm, a height h of the ribs 5, 6 of 5.3 mm is thus to be selected. The wall thickness d is identical in the embodiments with 5 mm Wälzkör- perdurchmesser and 10 mm Wälzkörperdurchmesser.

In the embodiment of FIG. 6, the bearing surface 2 of the bearing ring 1 has a curvature, wherein the outer side 19 of the bearing ring 1 is curved in a corresponding manner, the wall thickness d is thus constant. The curvature is formed such that the bearing ring 1 is supported in its axially outer regions on an only schematically illustrated component 20 with a cylindrical inner surface, while the axially central region of the bearing ring 1 is lifted from the component 20. In Fig. 6, the curvature of the bearing ring 1 is shown exaggerated. With regard to the relations between the wall thickness d, the height of the board h and the diameter of the associated rolling elements rolling on the bearing surface 2, the statements relating to FIG. 5 apply correspondingly. Preferably, the height h of the shelves 5, 6 measured in the radial direction is at least 1.3 times and at most three times, in particular at most twice, the wall thickness d of the bearing ring 1 in the area of its bearing surface 2. The entire bearing ring 1 inclusive the shelves 5, 6 is made by non-cutting forming. The maximum acting on the bearing surface 2 surface pressure during operation of the swash plate pivot bearing 11 is preferably not more than 2600 N / mm ² .

FIG. 7 shows in a symbolized manner a comparison between a rolling element arrangement according to the invention (in the illustration above) and a conventional rolling element arrangement (in the illustration below). In the upper half of FIG. 7, five rolling bodies 15 are guided in the bearing ring 1 in a common pocket 16 of the cage 14, which is not visible here. A rotational body 21 contacting the rolling elements 15 has a pronounced oblique position relative to the bearing ring 1 in the exaggerated representation. In a basically comparable manner, the swashplate 12 could be at least slightly inclined relative to the bearing ring 1, for example due to asymmetrical mechanical loads in the embodiment of FIG. 3 or in the embodiment of FIG. As illustrated in FIG. 7, however, the rolling elements 15 are largely located against the bearing surfaces 2, 13 of the parts 1, 21. This is due to the fact that the individual rolling elements 15 have at least a slight displaceability within the pocket 16 independently of each other. The height H of each rolling element 15 measured in the axial direction clearly falls short of its diameter D. On the other hand, the sum of the heights H of the five rolling elements 15 is greater than the rolling element diameter D. In an analogous manner in the exemplary embodiments according to FIGS each pocket 16 a plurality of disc-shaped rolling elements 15 is arranged.

The symbolically illustrated in the lower half of Figure 7 arrangement illustrates the storage of a rolling element 22 whose cross section corresponds approximately to the composite cross section of the five individual rolling elements 15. As can be seen from the illustration, the rolling element 22 has only almost point-to-point contact with the outer bearing surface 2. Thus, the arrangement with the individual rolling elements 22 extending almost over the entire width of the bearing surface 2 is considerably more sensitive to deflections or geometrical tolerances than that Inventive arrangement with a plurality of axially immediately adjacent rolling elements 15 within a pocket 16 of the cage 14. The individual disc-shaped rolling elements 15 do not necessarily have matching heights H on.

LIST OF REFERENCE NUMBERS

1 bearing ring

2 outer storage area

3 long side

4 long side

5 sidebar

6 sidebar

7 arc section

8 tail

9 corner rounding

10 corner rounding

11 swashplate pivot bearings

12 swash plate

13 inner storage area

14 cage

15 rolling elements

16 bag

17 support pins

18 metal ring

19 outside

20 component

21 rotating body

22 rolling elements

A axis d wall thickness

D diameter

E level

H height

K cage height

L bearing ring width

S gap height

Claims

Swash plate pivot bearing patent claims

1. swash plate pivot bearing, with

a hollow cylindrical outer bearing surface (2), which is formed by a bearing ring (1) for a swash plate (12) made of a bent metal strip, wherein the bearing surface (2) axially at least on one side by a radially inwardly extending, integrally formed from the Bearing ring (1) is formed bounded board (5,6),

- A cylindrical inner bearing surface (13) of the swash plate

(12)

an arcuate cage (14) arranged between the bearing surfaces (2, 13) and having a number of pockets (16),

a number in the pockets (16) arranged rolling elements (15), wherein per pocket (16) a plurality of rolling elements (15) are arranged axially adjacent to each other.

2. swash plate pivot bearing according to claim 1, characterized in that the cage (14) is made of a polymer material.

3. swash plate pivot bearing according to claim 1 or 2, character- ized in that the diameter (D) of a rolling element (15) is greater than its height (H).

4. swash plate pivot bearing according to one of claims 1 to 3, characterized in that the cage (14) has a in the axial direction on the bearing ring (1) also projecting support pin (17).

5. swash plate pivot bearing according to claim 4, characterized in that the support pin (17) is enclosed at least over part of its length by a metal ring (18).

6. swash plate pivot bearing according to one of claims 1 to 5, character- ized in that the board (5,6) has a height measured in the radial direction (h), the square root of the product of the wall thickness (d) of the Bearing ring (1) on the outer bearing surface (2) and the diameter (D) of the rolling elements (15) deviates by not more than a quarter.

7. swash plate pivot bearing according to one of claims 1 to 6, characterized in that the bearing ring (1) is curved in cross-section such that it is bent radially outwardly in its axially outer regions.