WIND TURBINE BEARING ASSEMBLY

Abstract

Provided is a bearing assembly of a wind turbine, the bearing assembly including a front bearing for a rotor shaft, a rear bearing for the rotor shaft, and a plurality of bearing connectors arranged between the front bearing and the rear bearing, wherein one end of a bearing connector is secured to the front bearing, and the other end of the bearing connector is secured to the rear bearing. Also provided is a wind turbine, and a method of designing a bearing assembly.

Claims

1. A bearing assembly of a wind turbine, the bearing assembly comprising: a front bearing for a rotor shaft; a rear bearing for the rotor shaft; and a plurality of bearing connectors arranged between the front bearing and the rear bearing, wherein a first end of a bearing connector is secured to the front bearing, and a second end of the bearing connector is secured to the rear bearing.

2. The bearing assembly according to claim 1, wherein dimensions of the bearing connector are chosen on a basis of a bearing dimension and/or a bearing mass and/or a distance between the front bearing and the rear bearing and/or a generator rated power.

3. The bearing assembly according to claim 1, wherein a number of bearing connectors, is chosen on a basis of a bearing dimension and/or a distance between the front bearing and the rear bearing and/or a generator rated power.

4. The bearing assembly according to claim 1, wherein the plurality of bearing connectors comprises a set of identical bearing connectors.

5. The bearing assembly according to claim 1, wherein a shape of the bearing connector is based on a form of a virtual cylinder extending between the front bearing and the rear bearing.

6. The bearing assembly according to claim 1, wherein the bearing connector comprises a curved end shaped on a basis of a variety of bearing diameters.

7. The bearing assembly according to claim 1, wherein the first end and the second end of the bearing connector comprises a number of through-holes to receive fasteners for securing the bearing connector to the front bearing and the rear bearing, respectively.

8. The bearing assembly according to claim 1, wherein the front bearing is mounted to a machine bed by a pair of diametrically opposed suspension points.

9. The bearing assembly according to claim 1, wherein the rear bearing is mounted to a machine bed by a pair of diametrically opposed suspension points.

10. A wind turbine comprising: an aerodynamic rotor arranged to turn a low-speed rotor shaft; and the bearing assembly according to claim 1 arranged about the low-speed rotor shaft.

11. The wind turbine according to claim 10, wherein the front bearing is arranged at a drive end of the low-speed rotor shaft, and the rear bearing is arranged at a gearbox end of the low-speed rotor shaft.

12. A method of designing the bearing assembly according to claim 1, the method comprising: obtaining design parameters of a wind turbine generator; obtaining construction parameters of physically separate front bearings and rear bearings for the generator rotor shaft; determining expected bearing loads during operation of the wind turbine generator; and determining design parameters of the plurality of bearing connectors arranged between the front bearing and the rear bearing.

13. The method according to claim 12, wherein a generator design parameter comprises rated power or rated torque.

14. The method according to claim 12, wherein a bearing construction parameter comprises a bearing diameter or a bearing separation.

15. The method according to claim 12, wherein a bearing connector design parameter comprises any of: number of bearing connectors a mass of the bearing connector, and a bearing connector material.

Description

BRIEF DESCRIPTION

[0022] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0023] FIG. 1 shows an embodiment of a bearing assembly;

[0024] FIG. 2 shows a detail of the bearing assembly of FIG. 1;

[0025] FIG. 3 shows an alternative embodiment of the bearing assembly;

[0026] FIG. 4 shows an alternative embodiment of the bearing assembly;

[0027] FIG. 5 shows a view into an embodiment of a partially assembled wind turbine according to embodiments of the invention;

[0028] FIG. 6 is as simplified block diagram indicating steps of a method; and

[0029] FIG. 7 shows a prior art bearing arrangement.

DETAILED DESCRIPTION

[0030] FIG. 1 shows an embodiment of the inventive bearing assembly 1 in a wind turbine 2. The wind turbine 2 has an aerodynamic rotor 23 comprising rotor blades that turn a rotor shaft 20. The rotor blades 23 are mounted to a spinner or hub, which is arranged at one end of a nacelle 26. A gearbox 21 converts the low-speed rotation of the rotor shaft 20 to a high-speed rotation of a generator rotor. The bearing assembly 1 is used to support and contain the rotor shaft 20 of the wind turbine generator between the aerodynamic rotor 23 (at the front of the drive train) and the gearbox 21 and generator 24 (at the rear of the drive train). The bearing assembly 1 comprises a front bearing 11 and a rear bearing 12. The front bearing 11 is mounted to a machine bed 22 at two diametrically opposed suspension points 11P (on opposite sides of the rotor shaft; only one suspension point 11P of the front bearing 11 can he seen in the drawing). Similarly, the rear bearing 12 is mounted to the machine bed 22 at two diametrically opposed suspension points 12P. During operation of the wind turbine, it is very important to ensure that loads are evenly and reliably transferred from the bearings to the machine bed 22 via the two pairs of suspension points 11P, 12P.

[0031] In the inventive bearing assembly 1, the from bearing 11 and rear bearing 12 are, connected by a set S_13A of stiffeners 13A. Each stiffener 13A of the set S_13A shown in this diagram is fastened at one end to the front bearing 11 and at the other end to the rear bearing 12 to mechanically connect the front and rear bearings 11, 12 as shown in in FIG. 2. Bolts can be inserted through holes in outer ends 131, 132 of a stiffener in order to fasten the stiffener to the bearings 11, 12. In this embodiment, the stiffener set S_13A comprises several stiffeners 13A evenly distributed about the space between the front and rear bearings 11, 12. The material and dimensions of the stiffeners 13A are chosen on the basis of the generator construction, and also on the basis of the expected loads to be transferred to the suspension points. The stiffeners 13A shown in this embodiment are not limited to connecting the front and rear bearings with the bearing diameters 11, 12 but can be used to join bearings with larger or smaller diameters. Similarly, the bearing separation D shown here is bridged by the set of stiffeners 13A. A slightly longer or shorter distance could he bridged simply by using an alternative set of slightly longer or shorter stiffeners, etc.

[0032] The set of stiffeners 13A shown in FIG. 1 serve in a specific generator design, i.e. for a generator with a certain power rating. As explained above, parameters such as rotor shaft diameter and/or distance between the front bearing 11 and rear bearing 21 can diner between generator types. Similarly, the expected loads arising during operation can depend on the power rating of a generator.

[0033] FIG. 3 shows a further embodiment of the inventive bearing assembly 1. Here, the bearing assembly 1 is used in a generator with a larger power rating than the generator of FIG. 1, and implements a different set of stiffeners 13B. In this embodiment, four stiffeners I3B are used, and the stiffeners 13B are thicker than the stiffeners 13A of FIG. 1, This stiffener set S_13B is characterized by a greater material strength, and can transfer higher loads to the suspension points 11P, 12P during operation of the wind turbine.

[0034] FIG. 4 shows a further embodiment of the inventive bearing assembly 1. Here, the bearing assembly 1 is used in a generator with a lower power rating than the generator of FIG. 1, and implements a different stiffener set S_13C. In this embodiment, only two stiffeners 13C are used. This smaller number of stiffeners is sufficient to transfer loads to the suspension points 11P, 12P during operation of the wind turbine.

[0035] FIG. 5 shows a view into a partially assembled wind turbine 2. The diagram shows that, to ensure safe and efficient operation of the generator components, the rotor shaft 20 will be held in place by a front bearing and a rear bearing, and these are each mounted to the machine bed 22 using diametrically opposed suspension points 11P, 12P. The diagram also shows a set of stiffeners 13A that mechanically connect the front and rear bearings 11, 12 in an embodiment of the invention. Depending on the generator design, a different set of stiffeners could be used to ensure the required load transfer behavior.

[0036] FIG. 6 is a simplified block diagram indicating steps of the inventive method. Design parameters P.sub.24 of a wind turbine generator are obtained, along with construction parameters P.sub.11, P.sub.12 of physically separate front and rear bearings for the generator's rotor shaft. With these known parameters, it is possible to compute the expected loads or forces F that will have to be withstood by the bearing suspension. Using this information, it is possible to determine design parameters P.sub.13 of a stiffener or stiffener set that will be used to connect or join the front and rear bearings. A generator design parameter P.sub.24 can be rated power, rated torque, etc. A bearing construction parameter P.sub.11, P.sub.12 can be bearing diameter, bearing mass, bearing separation, etc. A stiffener design parameter P.sub.13 can be mass, material shear strength, minimum required number, etc. A design module 6 can comprise a computation block 61 for determining the expected loads or forces and a simulation or modelling unit 62 for determining design parameters P.sub.13 of a suitable stiffener set.

[0037] FIG. 7 shows a prior art bearing arrangement. Here also, the diagram shows parts of a wind turbine of the type described in FIG. 1. In the prior art, a front bearing 71 and a rear bearing 72 are provided in a shared bearing housing 7. The bearing housing 7 is necessary in order to transfer loads through the suspension points 71P, 72P into the machine bed 22. Because the dimensions of the bearings 71, 72 and/or the distance between bearings may be different for different generator designs, the dimensions of the bearing housing will be different in each case. This adds considerably to the overall cost of manufacture.

[0038] 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.

[0039] 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.