WO2010022708A1 - Profiling of guide surfaces in rolling bearings with rim-guided cage - Google Patents

Abstract

The invention relates to a rolling bearing comprising an outer ring (5a), an inner ring (5b) and a rim-guided cage (6), wherein the cage (6) has a first cylindrical guide surface (8a) which is arranged concentrically with respect to a bearing axis (X) and by means of which the cage (6), by way of a second cylindrical guide surface (8b) arranged concentrically with respect to the bearing axis (X) and formed on a rim (9a, 9b) of one of the two rings (5a, 5b), is guided radially on said ring (5a, 5b). To provide a rolling bearing of said type which permits improved lubrication in relation to the prior art and at the same time has a simple and cost-effective design, it is proposed that that guide surface (8a, 8b) of the first and second guide surface (8a, 8b) which is situated radially at the outside has a profiling.

Description

 Name of the invention

Profiling of guide surfaces for rolling bearings with on-board cage

description

Field of the invention

The present invention relates to a roller bearing, comprising an outer ring, an inner ring and an on-board cage, wherein the cage has a first cylindrical and concentric to a bearing axis guide surface over which the cage by a second cylindrical and concentric with the bearing axis guide surface, which is formed on a board of one of the two rings is guided radially on this ring.

background

In contrast to roller-guided cages, on-board cages are guided radially on a bearing ring of the rolling bearing. For this purpose, both the cage and the corresponding bearing ring each have at least one guide on. In the case of an outboard-guided cage, a corresponding guide surface is located on at least one aboard the outer ring for this purpose. In the case of an inboard-guided cage, a corresponding guide surface is provided for this purpose at least on one side of the inner ring.

The guide surfaces on the cage and on the corresponding bearing ring are arranged concentrically with respect to the bearing axis. Between the guide surfaces of the cage and bearing ring, an annular gap is formed. This gap must be dimensioned in its radial extent such that at each operating time sufficient radial guidance of the cage is made possible, in particular, this gap may not be too large.

Due to this relatively small gap, however, problems can occur with respect to the lubrication between the cage and the cage bearing bearing, in particular on the guide surfaces. In built-in roller bearings with roller-guided cages, as shown by way of example in Fig. 1, the space between roller bearing 1 and adjacent construction 2, for example, cover or seal, filled with lubricant. As a result, the lubricant depot 3 is formed. Thus, a continuous exchange of lubricant between lubricant reservoir 3 and raceway 4a, 4b is made possible. In the case of an on-board cage, on the other hand, due to the small radial distance between the guide surfaces of the cage and the bearing ring, replacement of the lubricant between the lubricant reservoir and the raceway can only take place with difficulty. The leakage of lubricant from the track or the entry of lubricant into the track is difficult, ie there is a lubricant accumulation, and under certain circumstances sufficient lubrication is no longer ensured. Furthermore, the lubrication of the contact between the cage and bearing ring is insufficient. This lack of lubrication leads to wear, especially in the contact between the cage and bearing ring, ie in the guide surfaces. Ultimately, this leads to premature failure of the bearing. From DE 10 2005 008 668 A1 discloses a roller bearing cage is known, which should achieve a better lubrication of the bearing in that lubrication pockets, which are arranged in its lateral surface, have position-associated and channel-shaped lubrication grooves. The disadvantage, however, in addition to the relatively complex shape of the cage, the non-uniform over the circumference lubrication.

Object of the invention

The present invention is based on the object to provide a roller bearing of the type mentioned that allows over the prior art improved lubrication and at the same time has a simple and inexpensive construction.

Summary of the invention

This object is achieved according to the invention by the features of the independent claim.

Accordingly, the object is achieved in that the guide surface of the first and the second guide surface, which lies radially outward, has a profiling.

The invention is based on the recognition that a significant improvement in the lubricating effect can be achieved even by this relatively simple, constructive measure. Thus, the profiling invention forms on the one hand an additional lubricant depot. Since this additional Liehe lubricant reservoir is formed axially in the region of the two concentrically arranged guide surfaces on the cage and on the bearing ring, thereby already a significant improvement in the lubrication of the Rolling received. Thus, the additional lubricant reservoir is located exactly at the point that represented a weak point in the prior art due to the lack of lubrication.

On the other hand, the profiling according to the invention also makes it possible to improve the lubricant transport between the lubricant depot and the raceway. Thus, in principle, the lubricant located in the profiling will improve the replacement of the lubricant between the lubricant depot and the raceway. By an appropriate choice of profiling, e.g. Channels, grooves, indentations, etc. connecting the lubricant reservoir and the raceway, this aspect of the invention can still be significantly improved.

According to the invention, the profiling should be formed in each case on the radially outer guide surface. Due to the centrifugal force generated by the relative rotation of the inner ring, outer ring and cage on the lubricant, the lubricant is conveyed radially outward. By now the profiling is formed in the respective radially outer guide surface, the lubricant is pressed into this profiling. The advantages achieved by the profiling thus show a higher effect than if the profiling were formed in the radially inner guide surface. Even if, according to the invention, no profiling of the radially inner guide surface is provided, it is, however, in principle conceivable nevertheless to provide profiling on this guide surface.

According to a preferred embodiment, the cage has a third cylindrical guide surface arranged concentrically with respect to the bearing axis, over which the cage is connected by a fourth cylindrical guide surface which is concentrically arranged to the bearing axis and which is formed on a rim of one of the two rings Ring is guided radially, wherein that guide surface of the third and the fourth guide surface, which lies radially outward, has a profiling. In particular, the second and the fourth guide surface are arranged on different shelves of the same bearing ring, that is, the second guide surface is disposed on a first board and the fourth guide surface on a second board of a common bearing ring.

According to a preferred embodiment, the cage is outboard-guided and the guide surface, which lies in each case radially outward, is formed on at least one board of the outer ring. Of course, it is also conceivable to design the cage on the inboard, in which case the radial outer guide surface is part of the cage and thus the cage must be profiled accordingly.

In order to achieve a lubricant delivery effect in the axial direction through the rolling bearing, according to a preferred embodiment, the profiling comprises at least one groove. If this groove is now arranged at an angle other than 90 degrees to the bearing axis, during operation of the rolling bearing a force component along the extent of the groove acts on the lubricant in the groove, due to the contact of the lubricant with the radially inner guide surface and the Relative movement between the radially outer and radially inner guide surface. This force component creates a lubricant delivery effect along the extension of the groove. Advantageously, this groove extends axially over the entire extent of the first and / or second or third and / or fourth guide surface, whereby an optimal wetting of this guide surface is made possible with lubricant.

Although, in principle, a groove is already sufficient, in the context of the invention, however, a plurality of parallel or angled grooves with the same or different cross-sectional profile are also conceivable. Possible are also combinations of the at least one groove with other profiling types, eg circular depressions, which can serve as a lubricant reservoir. According to one embodiment, the groove extends helically over the cylindrical guide surface. In this case, the pitch angle of the spiral groove extending over its entire length may be constant or vary. It is conceivable that the pitch angle of the at least one groove relative to the axial extent of the guide surface is selected such that the at least one groove has substantially a single turn. That is, the at least one groove runs in the axial direction completely over the guide surface and encloses an angle of 360 degrees. In this case, a plurality of grooves offset from each other with the same or different pitch angle can be arranged. Preferably, the pitch angle of the at least one groove is in a range of 0 degrees to 5 degrees, in particular in a range of 0 angular minutes to 5 minutes, more particularly in a range of 0 angle seconds to 5 angle seconds. If the at least one groove is to be formed on two guide surfaces of the cage or of a bearing ring, slope angles of the same sign on both guide surfaces are preferably selected. This results in a lubricant delivery effect, which promotes the lubricant axially through the rolling bearing.

According to a further embodiment, at room temperature of the roller bearing, the ratio of groove depth to radial distance between the first and second guide surface and groove depth to radial distance between the third and fourth guide surface is in the range of 1 to 2 to 1 to 1, in particular at a value of 1 to 1. The latter means that the groove depth and the radial distance between the first and second guide surface and the groove depth and the radial distance between the third and fourth guide surface at room temperature is the same. With a diameter of the first and second or of the third and fourth guide surface of approximately 800 mm in each case, 0.5 mm can be selected as the groove depth, for example, this value applies to the rolling bearing at room temperature. According to a further embodiment, the groove has a kreissegmentför- miges, a rectangular, a u-shaped or a v-shaped cross-sectional profile. The cross-sectional profile results essentially from the tools used for introducing the groove. When screwed into the outer ring, in the case of an outboard-guided cage, the groove therefore has, for example, a circular segment-shaped cross-sectional profile.

According to another embodiment, the rolling bearing is lubricated with grease. It was found that, especially with highly viscous lubricant, the initially described lack of lubrication occurs in the contact area of cage and bearing ring. Finally, the lubricant transport is low compared to low viscosity lubricant, e.g. Lubricating oil, more affected by the narrow gap between the guide surfaces. The advantages of the roller bearing according to the invention therefore come into play particularly in grease-lubricated bearings. This can be a lifetime lubrication. In this case, the rolling bearing can be sealed so that no lubricant exchange takes place to the outside.

In principle, the invention can be applied to different rolling bearing types, e.g. can be used with ball bearings or with cylindrical roller bearings.

According to a further embodiment, the rolling bearing is used in a wind turbine. For example, the rolling bearing can be used as a main bearing, gearbox bearings or generator bearings. Also conceivable are applications in electric motor bearings or generally in sealed slewing bearings.

Brief description of the figures

An embodiment of the present invention will be explained below with reference to the accompanying figures. Show here 1 shows a rolling bearing with a connection construction according to the prior art,

2 is an axial view of an embodiment of a rolling bearing according to the invention,

Fig. 3 is a sectional view of a rolling bearing according to the embodiment of FIG. 2, and

4 is a detail view of an outer ring of the embodiment of FIG .. 2

Detailed description of the figures

Fig. 2 shows an axial view of an embodiment of a rolling bearing 1 according to the invention, comprising outer ring 5a, inner ring 5b, on-board cage 6 and rolling elements 7. The rolling elements 7 are circumferentially guided by the cage 6, so kept at a distance. However, the cage 6 is guided radially through the outer ring 5a, as the cage starts on both edges of the outer ring. For this purpose, corresponding guide surfaces are formed on the cage 6 and on the outer ring 5a.

Between the guide surfaces of the cage 6 and the guide surfaces of the outer ring 5a, a gap is formed, the radial extent in Fig. 2 is marked with 'a'. The dimension 'a' is selected to be correspondingly small in order to guide the cage radially, ie to ensure that it remains arranged substantially concentric with the bearing axis ¹ x ¹ protruding vertically from the plane of the drawing. Too large a measure of 'a' would allow a radial migration of the cage, whereby the circumferential guidance of the rolling elements would be impaired. A first, radially outwardly facing guide surface 8a is formed on the one-piece cage 6. The first guide surface 8a is arranged circumferentially on the rotationally symmetrical cage 6 and consists of a cylindrical surface. A second, radially inwardly facing guide surface 8b is arranged on the one-piece outer ring 5a. Also, the second guide surface 8b is arranged circumferentially and consists of a cylindrical surface. The first guide surface 8a and the second guide surface 8b are arranged concentrically with each other and have an approximately equal axial extent along the bearing axis X. In the view GE measured Fig. 2 lying back are not shown a third guide surface on the cage and a fourth guide surface on the outer ring. Both guide surfaces on the outer ring 5a are located on the two, the raceway enclosing shelves.

The rolling bearing 1 according to this embodiment is a ball bearing.

Fig. 3 shows a sectional view of a roller bearing according to the embodiment of FIG. 2 can be seen, the grooves 10 with a circular segment-shaped cross-sectional profile. The grooves 10 are formed on the first board 9a and the second board 9b of the outer ring 5a, namely, on the guide surfaces thereof for the cage, that is, the second guide surface 8b and the fourth guide surface 8d. In this embodiment, the value of the distance 'a' is substantially as large as the depth of the grooves 10 at room temperature.

Fig. 4 shows a detailed view of an outer ring of the embodiment of FIG. 2. The raceway 4a of the outer ring 5a for receiving the balls is bordered by the two rims 9a, 9b. On the first board 9a, the second guide surface 8b is arranged and on the second board 9b, the fourth guide surface 8d is arranged. Profiles in the form of grooves 10 are located on both guide surfaces 8b, 8d of the outer ring 5a. These have a cross-sectional profile in the form of a circular segment and are arranged at an angle 'alpha ¹ perpendicular to the bearing axis X. The angle 'alpha' corresponds to the pitch angle of a groove and is approximately 6 degrees in this embodiment. Due to the relatively small axial extent of the ribs 9a, 9b or the relatively large angle 'alpha', the grooves 10 thus do not completely run over the guide surfaces 8b, 8d. The pitch angle is constant for all grooves 10 of both guide surfaces 8b, 8d, in particular, this always has the same sign. In a rotation between the cage 6 and the outer ring 5a to each other thus due to the pitch angle 'alpha' lubricant is conveyed axially in one direction by the rolling bearing 1. A reversal of the direction of rotation causes a reversal of this conveying direction.

In this embodiment, the cage 6 on its guide surfaces no profiling.

LIST OF REFERENCE NUMBERS

1 rolling bearing

2 Connecting construction 3 Lubricant depot

4a raceway outer ring

4b raceway inner ring

5a outer ring

5b inner ring 6 cage

7 rolling elements

8a first guide surface

8b second guide surface

8c third guide surface 8d fourth guide surface

9a first board

9b second board

10 groove

Claims

claims 1. Rolling bearing, comprising an outer ring (5 a), an inner ring (5 b) and an on-board cage (6), wherein the cage (6) has a first cylindrical and a bearing axis (X) concentrically arranged guide surface (8 a) over which the cage (6) by a second cylindrical and to the bearing axis (X) concentrically arranged guide surface (8b) which is formed on a board (9a, 9b) of one of the two rings (5a, 5b), on this ring (5a, 5b) is guided radially, characterized in that that guide surface (8a, 8b) of the first and the second guide surface (8a, 8b), which lies radially outwardly has a profiling. 2. Rolling bearing according to claim 1, characterized in that the cage has a third cylindrical and concentric to the bearing axis arranged guide surface (8c) over which the cage (6) by a fourth cylindrical and concentric to the bearing axis arranged guide surface (8d) , which is formed on a board (9a, 9b) of one of the two rings (5a, 5b), is radially guided on this ring (5a, 5b), wherein the guide surface (8c, 8d) of the third and the fourth guide surface (8c, 8d), which lies radially outward, has a profiling. 3. Rolling bearing according to claim 1 or 2, characterized in that the cage (6) is guided outboard and the guide surface (8b, 8d), each radially outward, formed on at least one board (9a, 9b) of the outer ring (5a) is. 4. Rolling bearing according to one of the preceding claims, characterized in that the profiling at least one groove (10) summarizes. 5. Rolling bearing according to claim 4, characterized in that the at least one groove (10) extends helically over the cylindrical guide surface (8a, 8b, 8c, 8d). 6. Rolling bearing according to claim 5, characterized in that the pitch angle of the helically extending groove (10) in the range of 0 angular seconds to 5 arc seconds. 7. rolling bearing according to claim 5 or 6, characterized in that a groove depth and a radial distance between the first (8a) and second guide surface (8b) and the groove depth and a radial distance between the third (8c) and fourth (8d) Guide surface is the same at room temperature. 8. Rolling bearing according to one of claims 4-7, characterized marked, that the at least one groove (10) has a circular segment-shaped, a rectangular, a U-shaped or a V-shaped cross-sectional profile. 9. Rolling bearing according to one of the preceding claims, character- ized in that the rolling bearing is lubricated with grease. 10. Rolling bearing according to one of the preceding claims, characterized in that the rolling bearing is sealed. 11. Rolling bearing according to one of the preceding claims, character- ized in that the rolling bearing is a ball bearing, a cylindrical roller bearing or a tapered roller bearing. 12. Rolling bearing according to one of the preceding claims, characterized in that the rolling bearing is used in a wind turbine.