BEARING ARRANGEMENT FOR A WIND TURBINE, WIND TURBINE AND METHOD FOR MANUFACTURING A WIND TURBINE

Abstract

A bearing arrangement for a wind turbine is provided, including a bed frame, a support structure mounted to the bed frame, a shaft, bearings supporting the shaft rotatably around a shaft axis, and bearing housings supporting one of the bearings respectively, wherein the bearing housings are mounted on opposite faces of the support structure, the faces facing in the axial direction with respect to the shaft axis. The bearing arrangement provides high bending stiffness. At the same time, the bearings in the bearings housings are easily accessible for maintenance, for example.

Claims

1. A bearing arrangement for a wind turbine, comprising a bed frame, a support structure mounted to the bed frame, a shaft, bearings supporting the shaft rotatably around a shaft axis, and bearing housings supporting one of the bearings respectively, wherein the bearing housings are mounted on opposite faces of the support structure, the faces facing in the axial direction with respect to the shaft axis.

2. The bearing arrangement of claim 1, wherein the faces are arranged at opposite ends of the support structure.

3. The bearing arrangement of claim 1, wherein the faces face away from a geometric center of the support structure.

4. The bearing arrangement of claim 1, wherein the bearing housings are bolted to the faces with bolts extending parallel to the shaft axis.

5. The bearing arrangement of claim 1, wherein the shaft extends through the support structure.

6. The bearing arrangement of claim 1, wherein a cross-section of the support structure taken on a line in a direction perpendicular to the shaft axis has a closed geometry.

7. The bearing arrangement of claim 1, wherein the support structure has radial openings.

8. The bearing arrangement of claim 1, wherein the support structure is made from cast iron.

9. The bearing arrangement of claim 1, wherein the bearing housings are made from steel.

10. The bearing arrangement of claim 1, wherein the support structure is connected to the bed frame by one or more feet.

11. A wind turbine comprising the bearing arrangement of claim 1.

12. The wind turbine of claim 11, further comprising a rotor and a generator, wherein the shaft of the bearing arrangement connects the rotor with the generator.

13. A method for manufacturing the bearing arrangement of claim 1, comprising a) making the shaft stand with its shaft axis being orientated vertically, and b) lowering the support structure over the shaft and mounting the bearing housings to the opposite faces of the support structure.

14. The method of claim 13, wherein, prior to step b), the bearings are mounted to the vertically orientated shaft by heat-shrinking.

15. The method of claim 14, wherein a first of the bearing housings is mounted to a lower one of the bearings, the support structure is lowered over the shaft onto the first of the bearing housings, a second of the bearing housings is mounted to an upper one of bearings and/or the second of the bearing housings is mounted to the support structure.

Description

BRIEF DESCRIPTION

[0052] Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

[0053] FIG. 1 is a perspective view of a wind turbine according to an embodiment;

[0054] FIG. 2 is a perspective view of a bearing arrangement according to an embodiment;

[0055] FIG. 3 is a lengthwise cross-section taken from the bearing arrangement of FIG. 2; and

[0056] FIG. 4 shows a flowchart illustrating a method for manufacturing the bearing arrangement according to FIGS. 2 and 3 according to an embodiment.

DETAILED DESCRIPTION

[0057] FIG. 1 shows a wind turbine 1 according to an embodiment.

[0058] The wind turbine 1 comprises a rotor 2 connected to a generator 38 arranged inside a nacelle 3. The nacelle 3 is arranged at the upper end of a tower 4 of the wind turbine 1.

[0059] The rotor 2 comprises, for example, three rotor blades 5. The rotor blades 5 are connected to a hub 6 of the wind turbine 1. Rotors 2 of this kind may have diameters ranging from, for example, 50 to 160 meters or even more. The rotor blades 5 are subjected to high wind loads. Accordingly, high loads act on a main shaft (not shown in FIG. 1) connecting the hub 6 to the generator 38.

[0060] FIG. 2 shows a bearing arrangement 7 as used in the wind turbine 1 illustrated in FIG. 1. The bearing arrangement 7 is shown in a perspective view in FIG. 2. FIG. 3 illustrates a cross-section of the bearing arrangement 7. The cross-section is taken along a shaft axis 8 (see FIG. 2). The shaft axis 8 is the axis around which a main shaft 9 of the bearing arrangement 7 rotates when the rotor 2 drives the generator 38.

[0061] The main shaft 9 connects the hub 6 (see FIG. 1) to a coupling 10. The coupling 10 may be a shrink disc coupling. The coupling 10 connects the main shaft 9 to a gearbox 11. The gearbox 11 is connected to the generator 38 (see FIG. 1).

[0062] The main shaft 9 may be configured as a hollow shaft and may comprise a flange 12 for connecting to the hub 6 (see FIG. 1).

[0063] FIG. 2 also shows a bed frame 13 of the bearing arrangement 7. The bed frame 13 is connected to a yaw bearing (not shown), for example by bolts 14. Electric motors 15 drive gears 16 respectively. The gears 16 mesh with a ring gear (not shown) connected to the tower 4. By action of the electric motors 15, the bed frame 13 is thus able to yaw around a yaw axis which substantially corresponds to the vertical axis of the tower 4 (see FIG. 1).

[0064] The bearing arrangement 7 further comprises a support structure 17 which is, for example, made of cast iron.

[0065] According to the embodiment and best seen in FIG. 3, the support structure 17 has an hourglass shape with a minimum diameter D1 halfway along the shaft axis 8 and maximum diameters D2 at its respective ends 18, 19 along the shaft axis 8.

[0066] The support structure 17 has a cross-section (taken along a line perpendicular to the shaft axis 8) which is of a circular ring shape, thus defining a hollow space 20 inside through which the main shaft 9 extends. A wall thickness t of the support structure 17 may vary, for example, along the shaft axis 8.

[0067] Also, the support structure 17 may comprise through holes in its walls to reduce weight. One such through hole is shown in FIG. 3 for illustration purposes only and is denoted by reference numeral 21.

[0068] At its respective ends 18, 19, the support structure 17 has faces 22 and 23. The faces 22, 23 face in opposite directions denoted by x and x along the shaft axis 8. The faces 22, 23 have a circular ring shape. The faces 22, 23 face away from geometric center G of the support structure 17. In the example, the geometric center G of the support structure 17 is at the intersection of lines of symmetry S1, S2 about which the support structure 17 is symmetric. The line S1 is coaxial with the shaft axis 8. The line S2 runs at right angles with respect to the line S1. The geometric center G may well be defined otherwise.

[0069] The support structure 7 further comprises bearing housings 24, 25. The bearing housings 24, 25 are made from steel, in particular high alloy steel. The bearing houses 24, 25 may be machined or forged. Each bearing housing 24, 25 supports a bearing 26, 27 inside.

[0070] The bearings 26, 27 may be formed as gliding bearings or roller element bearings, in particular spherical bearings. One bearing, for example the bearing 25, may be formed as a fixed bearing, whereas the other bearing, for example, the bearing 24, is formed as a floating bearing.

[0071] At least one of the bearing housings 24, 25 may comprise a shoulder 28 or other means to hold the bearing 26, 27 in place along the shaft axis 8. Therein, the bearing housings 24, 25 support a respective outer race 29 of each bearing 24, 25. A respective inner race 30 is fixed to the main shaft 9. The inner races 30 may be fixed to the main shaft 9 by, for example, heat shrinking, as explained in more detail with regard to FIG. 4. Roller elements between the outer and inner race 29, 30 are denoted by reference numeral 31 in FIG. 3.

[0072] The bearing housing 24 is bolted to the face 22, and the bearing housing 25 is bolted to the face 23 of the support structure 17. For example, each bearing housing 24, 25 has a number of holes formed therein. The holes are, for example, spaced apart along a circular line C (when seen in a direction along the shaft axis 8see FIG. 2). Each bolt 32 reaches through a respective hole 33 in the bearing housings 24, 25, and is threaded into a corresponding threaded hole 34 inside the faces 22, 23. Respective heads of the bolts 32 are not shown in FIG. 3. The bolts 32 extend in parallel with respect to the shaft axis 8. The bolts 32 thus force each bearing housing 24, 25 to lie directly against a corresponding face 22, 23.

[0073] Returning now to FIG. 2, it can be seen that the support structure 17 comprises feet 35, 36 on either side, thus in total four feet. Each foot 35, 36 is bolted by bolts 37 to the bed frame 13. The bed frame 13 may be formed with pockets or the like to receive the feet 35, 36.

[0074] The shaft 9 thus runs for a portion of its length through the support structure 17, while being supported by the bearings 26, 27 at opposite ends of the support structure 17. Thus, when a bending moment is applied to the main shaft 9, the bearings 26, 27, the bearing housing 24, 25 and the support structure 17 form a stiff unit counter-acting said moment. All forces resulting from said moment are transferred via the feet 35, 36 of the support structure 17 into the bed frame 13. There is no single point support of the bearings 26, 27 directly at the bed frame 13. Thus, all forces need to flow through the feet 35, 36.

[0075] At the same time, the bearing housings 24, 25 and thus the bearings 26, 27 are easily accessible from the outside, for example, to do maintenance, such as replacing seals on the bearings 26, 27.

[0076] FIG. 4 illustrates a method for manufacturing the bearing arrangement 7 of FIGS. 2 and 3.

[0077] In a first step 100, the main shaft 9 is made to stand upright with its shaft axis 8 being orientated vertically. For example, in this position, the main shaft 9 stands on its flange 12 serving as a foot on a factory floor.

[0078] In a step 200, the bearings 26, 27 are each heated and then moved, from above, down along the shaft axis 8 into their respective locations. At those locations, the bearings 26, 27 cool down and are thus heat-shrunk onto the main shaft 9. To this end, the lower bearing 26 has a larger inner diameter than the upper bearing 27.

[0079] In a step 300, the bearing housing 24 is fitted to the lower bearing 26.

[0080] In a step 400, the support structure 17 is lowered from above (held there, for example, with a crane) down along the shaft axis 8 until the lower face 22 comes to lie against the bearing housing 24. For example, at this position, the lower bearing housing 24 is connected by the bolts 32 to the support structure 17 (step 500).

[0081] In a step 600, the upper bearing housing 25 is fitted to the upper bearing 27. At this time, the upper bearing housing 25 lies against the upper face 23 of the support structure 17. Thereafter, the upper bearing housing 25 is bolted by bolts 32 to the support structure 17 (step 700).

[0082] In a step 800, the unit made up of the main shaft 9, the support structure 17, the bearing housings 24, 25 and the bearings 26, 27 is turned into a horizontal position and lifted onto the bed frame 13. In this position, the feet 35, 36 of the support structure 17 are bolted by the bolts 37 to the bed frame 13. Thereafter, the coupling 10 is fitted to the main shaft 9. Then, the gearbox 11 is mounted on the bed frame 13 and connected to the coupling 10.

[0083] Although the invention has been illustrated and described in greater detail with reference to the preferred exemplary embodiment, the invention is not limited to the examples disclosed, and further variations can be inferred by a person skilled in the art, without departing from the scope of protection of the invention.

[0084] 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.