FLUID FILM BEARING COMPRISING BEARING PADS AND METHOD OF REPLACING BEARING PADS

Abstract

A fluid film bearing for a rotor hub of a wind turbine includes a first part and a second part rotatably coupled to each other about a longitudinal axis. The first part includes an annular first sliding surface extending in the circumferential direction of the fluid film bearing along the first part. In addition, the second part includes a support structure and a first group of bearing pads coupled to the support structure and having a bearing pad sliding surface configured to slide on the first sliding surface. In addition, the fluid film bearing further includes a seal arranged between the first part and the second part.

Claims

1. A fluid film bearing for a rotor hub of a wind turbine comprising a first part and a second part rotatably coupled to each other about a longitudinal axis, wherein the first part comprises an annular first sliding surface extending in the circumferential direction of the fluid film bearing along the first part, wherein the second part comprises a support structure and a first group of bearing pads coupled to the support structure and having a bearing pad sliding surface configured to slide on the first sliding surface, wherein the fluid film bearing further comprises a seal arranged between the first part and the second part for sealing an inner space of the fluid film bearing in which the bearing pads are arranged, wherein the seal covers an opening of the inner space, wherein the seal is detachable, wherein the opening is wide enough for allowing a replacement of a plurality of bearing pads through the opening when the seal is detached.

2. The fluid film bearing according to claim 1, wherein the first group of bearing pads comprises axial bearing pads.

3. The fluid film bearing according to claim 1, wherein the first part further comprises an annular second sliding surface extending in the circumferential direction of the fluid film bearing along the first part, wherein the second part further comprises a second group of bearing pads coupled to the support structure and having a bearing pad sliding surface configured to slide on the second sliding surface, wherein the second group of bearing pads comprises radial bearing pads.

4. The fluid film bearing according to claim 1, wherein the first part further comprises an annular third sliding surface extending in the circumferential direction of the fluid film bearing along the first part, wherein the second part further comprises a third group of bearing pads coupled to the support structure and having a bearing pad sliding surface configured to slide on the third sliding surface, wherein the third group of bearing pads comprises axial bearing pads.

5. The fluid film bearing according to claim 1, wherein the first part is arranged on an outer circumference of the second part and/or radially outwards of the second part.

6. The fluid film bearing according to claim 1, wherein the first part is a rotatable part and the second part is a stationary part.

7. The fluid film bearing according to claim 1, wherein the bearing pads are kept in position between the first part and the second part by coupling means applying a load between the first part and the second part, thereby applying a force to the bearing pads arranged between the first part and the second part and preventing the bearing pads to shift, whereby the coupling means are configured to release the load between the first part and the second part by untightening the coupling means.

8. The fluid film bearing according to claim 7, wherein the coupling means are bolts.

9. The fluid film bearing according to claim 1, wherein each bearing pad is arranged in a cavity or recess of the support structure.

10. The fluid film bearing according to claim 1, wherein the seal is a sealing ring. joyce

11. The fluid film bearing according to claim 1, wherein the seal is coupled to the first part or to the second part by seal coupling means.

12. A method of replacing bearing pads of a fluid film bearing according to claim 1 through an opening of an inner space of the fluid film bearing, the method comprising the steps of: detaching a seal from the opening arranged between the first part and the second part sealing the inner space of the fluid film bearing in which the bearing pads are arranged, reducing a load between the first part and the second part by releasing a force applied to a first bearing pad and/or by applying a force to the first part and/or the second part, displacing the first bearing pad for reaching the opening, pulling the first bearing pad through the opening, inserting a replacement first bearing pad through the opening and displacing the replacement first bearing pad to the original position of the replaced first bearing pad, increasing the load between the first part and the second part by increasing the force applied to the replacement first bearing pad and/or by applying a force to the first part and/or the second part so that the replacement first bearing pad is kept in position, and attaching the seal at the opening.

13. The method of replacing bearing pads of a fluid film bearing according to claim 12, wherein a second bearing pad is replaced through the opening following the steps for replacing the first bearing pad through the opening.

14. The method of replacing bearing pads of a fluid film bearing according to claim 13, wherein the first and second bearing pads are both replaced before the load between the first part and the second part is increased.

15. A wind turbine comprising the fluid film bearing according to claim 1.

Description

BRIEF DESCRIPTION

[0079] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0080] FIG. 1 a wind turbine comprising a fluid film bearing as known in the prior art; and

[0081] FIG. 2 a fluid film bearing for a rotor hub of a wind turbine according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0082] FIG. 1 shows a detailed view of a wind turbine 1 as known in the conventional art that comprises a rotor hub 3 rotatably connected to a housing 4 of a generator of the wind turbine 1 using a fluid film bearing 2. The rotor hub 3 is mounted to a first part 10 of the fluid film bearing 2 using a torque-prove connection, for example a flange connection. Alternatively, the hub 3 and the first part 10 can be formed, e.g. cast, as a single piece.

[0083] The first part 10 is also connected to the housing 4 using a torque-prove connection. The housing 4 can be used to carry a rotor of a generator of the wind turbine 1 that is not shown in FIG. 1 for reasons of simplicity and clarity.

[0084] The second part 11 of the fluid film bearing 2 has an annular shape and can be formed as one piece or connected to a stator shaft which carries the stator of the generator of the wind turbine 1 that is not shown for reasons of simplicity and clarity.

[0085] Hence, the first part 10 is the rotatable part of the fluid film bearing 2 connected to the rotor hub 3 and to the housing 4 and the second part 11 is the stationary part of the fluid film bearing 2 connected to the stationary shaft supporting the stator of the generator.

[0086] Details concerning the lubrication of the fluid film bearing, e.g., seals and pumps that can optionally be used to transport the lubricant, are omitted in the present figure.

[0087] The bearing pads 12, 13 are distributed along a circumference of the second part 11 in three different groups for supporting the first part 10. The first and third group of bearing pads 12, 13 is a group formed by axial bearing pads 12, which slide on the first and third sliding surface 14, 16 respectively and provide axial support in both axial directions. The second group of bearing pads 12, 13 is a group formed by radial bearing pads 13, which slide on the second sliding surface 15 and provide radial support. Therefore, the first part 10 is supported in both axial directions and in the radial direction on the second part 11.

[0088] Each of the bearing pads 12, 13 has a respective bearing pad sliding surface 17 that supports the annular first sliding surface 14 and the annular third sliding surface 16 of the first part 10 in the axial direction and the annular second sliding surface 15 in the radial direction. The sliding surfaces 14, 15, 16 can e.g., be coated to improve the robustness of the sliding surface and/or further reduce friction. While the sliding surfaces 14, 15, 16 are typically not in direct contact during the normal operation, since a thin lubricant film is arranged between the sliding surfaces 14, 15, 16, contact between the sliding surfaces 14, 15, 16 can e.g., occur at slow rotating speeds or when pumps used to transport the lubricant are not working.

[0089] The bearing pad sliding surface 17 can have a convex shape. The convex shape of the bearing pad sliding surface 17 can match the shape of the respective annular sliding surface 14, 15, 16, that is at least approximately circular in the same sectional plane. Another advantage of using a convex surface is an avoidance of acute angles at the edges of the bearing pad sliding surface 17. This can help to reduce wear and tear of the bearing pad sliding surface 17 and the annular sliding surface 14, 15, 16.

[0090] Bearing pads 12, 13 typically allow a certain amount of tilting of the bearing pad sliding surface 17 of the respective bearing pad 12, 13 with respect to a support section of the bearing pad 12, 13 used to support the bearing pad 12, 13 against a mounting surface or some other mounting point. The bearing pad sliding surface 17 is typically provided by a contact section that is mounted to the support section by a mechanism to allow for the tilting, e.g., by a pivot or a ball-in-socket connection. It is also possible to provide a flex support as the mechanism that allows tilting. The contact section and the support section can be formed from the same material connected by a thinner part of the same material forming the mechanism allowing the tilting.

[0091] The first part 10 is arranged on an outer circumference of the second part 11. The support structure 18 of the second part 11 comprises a plurality of windows 20 providing access to the bearing pads 12, 13 for replacing the bearing pads 12, 13. Each window 20 corresponds to one bearing pad 12, 13, hence the number of windows 20 and the number of bearing pads 12, 13 is the same. In other words, for each bearing pad 12, 13 there is a window 20 in the support structure 18 for replacement of the bearing pad 12, 13.

[0092] As indicated by the arrows, the bearing pads 12, 13 are radially removed and the replacement pads inserted into windows 20 of the support structure 18 of the second bearing part 11 when they need to be replaced. As each bearing pad 12, 13 has a specific window 20 for this process, the bearing pad 12, 13 to be replaced is taken out of the seat in a radial direction towards the centre of the second part 12 of the fluid film bearing 2. This process applies to axial bearing pads 12 and to radial bearing pads 13.

[0093] After removal of bearing pads 12, 13 through the respective window 20, the bearing pads 12, 13 can then be transported out of the fluid film bearing 2 and out of the wind turbine 1.

[0094] After removal of bearing pads 12, 13 through the respective window 20, replacement bearing pads 12, 13 can be inserted through the respective windows 20 and be placed on the original position of the removed bearing pads 12, 13 between the support structure 18 and the first part 10.

[0095] In particular, the replacement of bearing pads 12, 13 may be performed manually or by using a lifting device manually installed prior to the replacement procedure in the vicinity of the fluid film bearing 2.

[0096] FIG. 2 shows a fluid film bearing 2 for a rotor hub 3 of a wind turbine 1 according to an embodiment of the present invention. The fluid film bearing 2 comprises a first part 10 and a second part 11 rotatably coupled to each other about a longitudinal axis.

[0097] The second part 11 comprises a support structure 18 and a first group of bearing pads 12, 13 coupled to the support structure 18.

[0098] The fluid film bearing 2 further comprises a seal 19, which is a sealing ring, arranged between the first part 10 and the second part 11 for sealing an inner space of the fluid film bearing 2 in which the bearing pads 12, 13 are arranged, wherein the seal 19 covers an opening 24 of the inner space. The seal 19 is detachable, wherein the opening 24 is wide enough for allowing a replacement of a plurality of bearing pads 12, 13 through the opening 24 when the seal 19 is detached.

[0099] The seal 19 is coupled to the first part 10 by seal coupling means 23, which are bolts as shown in the figure.

[0100] Although not shown in the figure, the support structure 18 can comprise windows 20 for replacing the bearing pads 12, 13 which cannot be replaced through the opening 24.

[0101] The bearing pads 12, 13 are kept in position between the first part 10 and the second part 11 by coupling means 22 applying a load between the first part 10 and the second part 11, thereby applying a force to the bearing pads 12, 13 arranged between the first part 10 and the second part 11 and preventing the bearing pads 12, 13 to shift. The coupling means 22 are configured to release the load between the first part 10 and the second part 11 by untightening the coupling means 22. The coupling means 22 are a bolted connection. In particular, the bearing pads 12, 13 are fixed to the fluid film bearing 2 by the bolted connection comprising a plurality of bolts exerting a pressure between the first part 10 and the second part 11. In a mounted state of the bearing pads 12, 13, a force is acting on the bearing pads 12, 13 due to the weight of the first part 10 and the second part 11 and/or due to the bolted connection.

[0102] The coupling means 22 can also be directly used to fix the bearing pads 12, 13 to the second part 11. By tightening the coupling means 22, more force is exerted from the bearing pad 12, 13 to the sliding surface 14, 15, 16. The bearing pads 12, 13 are fixed on the stationary part of the bearing 2 each by a bolted connection comprising a plurality of bolts.

[0103] After untightening the bolts, the bearing pads 12, 13, or the sliding part of the bearing pads 12, 13, can be removed from the fluid film bearing 2. Depending on the location of the opening 24 and of any possible further windows 20, the bearing pads 12, 13 are removed in a radial direction or in an axial direction. After insertion of the replacement bearing pads 12, 13, the load can be applied again to keep the bearing pads 12, 13 by tightening the coupling means 22.

[0104] Although the present invention has been disclosed in the form of 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.

[0105] 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. [0106] Reference numbers [0107] 1 Wind turbine [0108] 2 Fluid film bearing [0109] 3 Rotor hub [0110] 4 Housing [0111] 10 First part [0112] 11 Second part [0113] 12 Axial bearing pad [0114] 13 Radial bearing pad [0115] 14 First sliding surface [0116] 15 Second sliding surface (for radial pads) [0117] 16 Third sliding surface [0118] 17 Bearing pad sliding surface [0119] 18 Support structure [0120] 19 Seal [0121] 20 Window [0122] 22 Coupling means [0123] 23 Seal coupling means [0124] 24 Opening