ROLLING BEARING AND WIND TURBINE COMPRISING A ROLLING BEARING

Abstract

Provided is a rolling bearing, in particular for a wind turbine, including an inner race, an outer race, a plurality of rolling elements arranged between the inner race and the outer race, and lubricant for lubricating the rolling bearing, wherein the inner race and the outer race each have a bearing surface with a contact zone in contact with the rolling elements, the bearing surface of at least one of the inner race and the outer race has a portion having a lipophobic surface for repelling the lubricant. The suggested rolling bearing has the advantage that the lubricant in the bearing does not stick to the portion, where it is useless for lubricating the bearing. Therefore, the rolling bearing can have a better lubrication, since the lubricant is directed towards the contact zone, where contact between the races and the rolling elements takes place.

Claims

1. A rolling bearing for a wind turbine, comprising an inner race, an outer race, a plurality of rolling elements arranged between the inner race and the outer race, and lubricant for lubricating the rolling bearing, wherein the inner race and the outer race each have a bearing surface with a contact zone in contact with the rolling elements, the bearing surface of at least one of the inner race and the outer race has a portion having a lipophobic surface for repelling the lubricant.

2. The rolling bearing according to claim 1, wherein the portion is directly adjacent to the contact zone.

3. The rolling bearing according to claim 1, wherein the portion comprises a lipophobic material.

4. The rolling bearing according to claim 1, wherein the lipophobic surface is formed as a coating.

5. The rolling bearing according to claim 1, wherein the portion comprises a microstructured material or a microporous material.

6. The rolling bearing according to claim 1, wherein a sealing portion for sealing the rolling bearing is arranged between the inner race and the outer race and a surface portion directly adjacent to the sealing portion has a lipophobic surface for repelling the lubricant.

7. The rolling bearing according to claim 1, wherein the contact zone has a lipophilic surface.

8. The rolling bearing according to claim 1, wherein the rolling elements have a lipophilic surface.

9. The rolling bearing according to claim 1, wherein the lubricant is oil.

10. The rolling bearing according to claim 1, wherein the lubricant is grease.

11. The rolling bearing according to claim 1, wherein the portion comprises a polymeric coating.

12. The rolling bearing according to claim 11, wherein the polymeric coating is a fluoropolymer coating.

13. The rolling bearing according to claim 1, wherein the rolling bearing is implemented as a ball bearing, as a cylindrical rolling bearing, as at least one of a spherical rolling bearing and as a tapered rolling bearing.

14. A wind turbine having a rolling bearing according to claim 1 as at least one of a main bearing and as a blade bearing.

Description

BRIEF DESCRIPTION

[0046] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0047] FIG. 1 shows a schematic cross-section of an example of a rolling bearing;

[0048] FIG. 2 shows a schematic cross-section of an example of a shaft supported rotationally by two rolling bearings;

[0049] FIG. 3 shows a schematic cross-section of a further example of a rolling bearing; and

[0050] FIG. 4 shows a schematic of a wind turbine.

[0051] In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

DETAILED DESCRIPTION

[0052] FIG. 1 shows a schematic cross-section of an example of a rolling bearing 10. The rolling bearing 10 is implemented as a ball bearing. The ball bearing 10 comprises an inner race 12 and an outer race 14, which are made from hardened steel. Between the inner race 12 and the outer race 14 a rolling element 19 is arranged. The rolling element 19 is a ball in this case. The ball bearing 10 may further comprise a cage (not shown) for keeping the ball 19.

[0053] Both the inner race 12 and the outer race 14 are specifically designed on their sides facing towards each other. In particular, a contact zone 15 is arranged at a position where the ball 19 has contact to the inner race 12 or the outer race 14 in normal operating conditions. The contact zone 15 is worked to be very tough and robust. Next to the contact zone 15, on both sides, a (side) portion 16 is arranged. The portion 16 is arranged in a position where the ball 19 will not have contact at normal operating conditions. The ball bearing 10 is lubricated by using a lubricant 18 such as oil and/or grease.

[0054] The portions 16 have a lipophobic surface 17 (reference numerals are only shown on the left side, for better overview). For example, this is provided by a lipophobic coating. Thus, the lubricant 18 is repelled from the lipophobic surface 17. That is, the lubricant does not stick to the lipophobic surface 17. Further, the contact zone 15 comprises a lipophilic coating, which provides lipophilic property to the contact zone 15. Therefore, since the portion 16 is lipophobic and the contact zone 15 is lipophilic, the lubricant 18 stays on the contact zone 15. Even if the lubricant 18 is pushed to the portion 16, for example by the ball 19, the lubricant 17 returns to the contact zone 15. Therefore, the lubricant 17 stays effective in lubricating the ball bearing 10. That is, a friction between the ball 19 and the contact zone 15 of both the inner race 12 and the outer race 14 is reduced. Further, wear of the ball bearing 10 is reduced.

[0055] FIG. 2 shows a schematic cross-section of an example of a shaft 22 supported rotationally by two rolling bearings 10, for example the ball bearings 10 described in reference to FIG. 1. In FIG. 2, only the upper half of the shaft is shown. For example, the shaft 22 is a shaft of a rotor of a wind turbine 1 (see FIG. 3) and has a diameter of 2.5 m. The shaft 22 is supported rotationally about a rotation axis X.

[0056] The inner races 12 of the rolling bearings 10 are arranged on the shaft 22. The outer races 14 of the rolling bearings 10 are arranged on bearing flanges 20. The bearing flanges 20 is implemented in a housing 4 (see FIG. 3) supporting the rotor and a generator (not shown), for example.

[0057] By using the rolling bearings 10, the shaft 22 is supported very smoothly and with very low friction. This is due to the lubricant 18 (see FIG. 1) being kept in the contact zone 15 (see FIG. 1) of the rolling bearings 10 by the specific design of the inner race 12 and the outer race 14, as described with reference to FIG. 1.

[0058] FIG. 3 shows a schematic cross-section of a further example of a rolling bearing 10. The rolling bearing 10 has two rows of tapered or cylindrical rolling elements 19. In FIG. 3, only one half of the rolling bearing 10 is shown, the second half is symmetrically identical. The contact zone 15 on the inner race 12 and the outer race 14 has a width corresponding to an effective length of the rolling elements 19, which is the part of the rolling elements 19 that is engaged in contact with the inner race 12 or outer race 14. The rolling elements 19 are, for example, held in place and guided by edges 24, 26 formed on the inner race 12. However, a cage (not shown) may be employed for guiding the rolling elements 19 instead of or additionally to the edges 24, 26.

[0059] In FIG. 3, portions 16 having a lipophobic surface 17 arranged on both the inner race 12 and the outer race 14 are shown only on one side of the rolling elements 19. However, such portions 16 may be present also on the other side of the rolling elements 19.

[0060] The rolling bearing 10 has a fixing element 29 for fixing a sealing element 31 between the inner race 12 and the outer race 14. That is, a sealing portion 30 is arranged between the inner race 12 and the outer race 14. Next to the sealing portion 30 or the seal 31 is a surface portion 32 of the inner race 12, which has a lipophobic surface, similar to the portion 16. A surface portion 28 of the edge 26 is essentially parallel to a side of the rolling elements 19 and is a guide for the rolling elements 19. Therefore, contact between the rolling elements 19 and the surface portion 28 may take place. The surface portion 28 is therefore lubricated by lubricant 18 (not shown in FIG. 3). Thus, the surface portion 28 is not lipophobic, but has a lipophilic surface.

[0061] Between the rolling elements 19, the inner race 12, the outer race 14 and the fixing element 29, a space A is formed. Since the surface portion 32 has a lipophobic surface, lubricant 18 does not stick to it. Thus, lubricant 18 accumulating in space A is reduced. A pressure of lubricant 18 on seal 31 that may be exerted when lubricant 18 is pushed into space A by rolling elements 19 is reduced, since the space A is not pre-occupied by lubricant 18. Further, lubrication of surface portion 28 is enhanced. Other surfaces than described here may be modified to have lipophobic properties.

[0062] FIG. 4 shows a schematic of a wind turbine 1. The wind turbine 1 comprises a rotor with three blades 2. The blades 2 drive a shaft 22 (see FIG. 2) that is supported rotationally by two rolling bearings 10, for example the rolling bearings 10 described with reference to one of FIGS. 1 to 3. The rolling bearings 10 are thus the main bearings of the wind turbine 1. The rolling bearings 10 are fixed with their outer race 14 on a main bearing flange (not shown) arranged in a housing 3 of the wind turbine 1. The shaft 22 drives a generator (not shown) arranged in the housing 3. The housing 3 is arranged on a pole 4. For example, the wind turbine 1 has a high of over 100 m and the rotor of the wind turbine 1 has a diameter of 50 m and up to 250 m.

[0063] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0064] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.