Wind turbine and pitch bearing of the wind turbine

Abstract

Wind turbine comprising at least a pitch bearing comprising at least two rings, each of the at least two rings attached to a wind turbine component, being a first wind turbine component a blade and a second wind turbine component a hub, and further comprising at least one bearing reinforcement attached to at least one of the two rings. The invention also relates to the pitch bearing of the wind turbine.

Claims

1. A pitch bearing comprising: at least two rings, each of the at least two rings being attached to a first or second wind turbine component, the first wind turbine component being a blade and the second wind turbine component being hub; and at least one bearing reinforcement attached to at least one of the two rings, wherein the at least one bearing reinforcement comprises a bearing reinforcement thickness that is variable along a circumferential direction of the pitch bearing, wherein the at least one bearing reinforcement comprises two ends and a central part disposed between the ends in a circumferential direction of the pitch bearing wherein the bearing reinforcement thickness of the at least one bearing reinforcement is variable along the circumferential direction of the pitch bearing from the ends towards the central part of the at least one bearing reinforcement, wherein a ratio between a maximum bearing reinforcement thickness and a bearing thickness is at least 15%, and wherein the at least one bearing reinforcement is attached to at least one of the two rings such that, in use, the at least one of the two rings is disposed, along the axial direction of the pitch bearing, between the at least one bearing reinforcement and the wind turbine component to which the at least one of the two rings is attached.

2. The pitch bearing according to claim 1, wherein the bearing reinforcement thickness of the at least one bearing reinforcement reaches a maximum reinforcement thickness in the central part of the at least one bearing reinforcement.

3. The pitch bearing according to claim 1, wherein the bearing reinforcement thickness of the at least one bearing reinforcement is variable along the circumferential direction of the pitch bearing from the ends towards the central part of the at least one bearing reinforcement in a symmetrical manner.

4. The pitch bearing according to claim 1, wherein the at least one bearing reinforcement is attached to at least one of the two rings such that a maximum reinforcement thickness is located coinciding with an area of the pitch bearing subjected to the highest stresses or deformations in the pitch bearing.

5. The pitch bearing according to claim 1, wherein the bearing reinforcement thickness is variable in the circumferential direction of the pitch bearing in a continuous manner in at least a part of the at least one bearing reinforcement.

6. The pitch bearing according to claim 1, wherein the at least one bearing reinforcement comprises recesses in correspondence with bolts to provide a flat surface to support bolt heads.

7. The pitch bearing according to claim 1, wherein the at least one bearing reinforcement thickness is variable in the circumferential direction of the pitch bearing in a discontinuous manner.

8. The pitch bearing according to claim 7, wherein the at least one bearing reinforcement comprises at least two stacked reinforcing plates.

9. The pitch bearing according to claim 8, wherein each one of the at least two stacked reinforcing plates has a different longitudinal dimension and is stacked along a different angular sector over the at least one of the two rings to which the at least one bearing reinforcement is attached.

10. The pitch bearing according to claim 9, wherein one of the stacked reinforcing plates is closer to the at least one of the two rings to which the at least one bearing reinforcement is attached than the at least one other reinforcement plate of the stacked reinforcing plates and wherein the longitudinal dimension of the stacked reinforcing plate closer to the at least one of the two rings to which the at least one bearing reinforcement is attached is greater than the longitudinal dimension of the at least one other stacked reinforcing plate such that it extends along a greater angular sector over the at least one of the two rings to which the at least one bearing reinforcement is attached.

11. The pitch bearing according to claim 8, wherein one of the stacked reinforcing plates is closer to the at least one of the two rings to which the at least one bearing reinforcement is attached than the at least one other reinforcement plate of the stacked reinforcing plates and wherein a thickness of the stacked reinforcing plate closer to the at least one of the two rings to which the at least one bearing reinforcement is attached is greater than a thickness of the at least one other stacked reinforcing plate.

12. The pitch bearing according to claim 8, wherein one of the stacked reinforcing plate is closer to the at least one of the two rings to which the at least one bearing reinforcement is attached than the at least one other reinforcement plate of the stacked reinforcing plates and wherein a thickness of the stacked reinforcing plate closer to the at least one of the two rings to which the at least one bearing reinforcement is attached is smaller than a thickness of the at least one other stacked reinforcing plate.

13. The pitch bearing according to claim 8, wherein the stacked reinforcing plates have substantially the same thickness.

14. The pitch bearing according to claim 1, wherein a width of the at least one bearing reinforcement is substantially equal to a width of the at least one of the two rings to which the at least one bearing reinforcement is attached.

15. The pitch bearing according to claim 1, wherein the pitch bearing is a rolling element bearing and the at least one bearing reinforcement is located coinciding with an area of the pitch bearing near to the position of an orifice for the insertion of the rolling element.

16. The pitch bearing according to claim 1, wherein the at least two rings comprise an outer ring and an inner ring, wherein the at least one bearing reinforcement is attached to the outer ring.

17. The pitch bearing according to claim 16, wherein the outer ring is attached to the hub, wherein the at least one bearing reinforcement is attached to a planar surface of the outer ring opposite to a planar surface closer to the hub.

18. A wind turbine comprising the pitch bearing according to claim 1.

19. The pitch bearing according to claim 1, wherein the ratio between the maximum bearing reinforcement thickness and the bearing thickness is at least 25%.

Description

DESCRIPTION OF THE DRAWINGS

(1) To complement the description being made and in order to aid towards a better understanding of the characteristics of the invention, in accordance with a preferred example of practical embodiment thereof, a set of drawings is attached as an integral part of said description wherein, with illustrative and non-limiting character, the following has been represented:

(2) FIG. 1 shows the location of a pitch bearing of the wind turbine between at least a root of a wind turbine blade and at least one hub connection. In the figure the location surface of the pitch bearing that is not in contact with the root blade or with the hub can be appreciated.

(3) FIG. 2 shows a pitch bearing of the present invention with a bearing reinforcement attached to the outer ring.

(4) FIG. 3a shows a top view of a pitch bearing wherein the bearing reinforcement has a continuous thickness variation in at least part of its longitudinal dimension.

(5) FIG. 3b is a section view DD of FIG. 3a.

(6) FIG. 3c-d show details of embodiments of the bearing reinforcement having a continuous thickness variation in at least part of its longitudinal dimension.

(7) FIG. 4 shows an embodiment of the bearing reinforcement in which it comprises a plurality of stacked reinforcing plates.

(8) FIG. 5 shows a pitch bearing comprising two bearing reinforcements placed opposite to each other.

(9) FIG. 6 shows a pitch bearing comprising one bearing reinforcement.

(10) FIG. 7 shows a pitch bearing comprising a plurality of bearing reinforcements placed together.

(11) FIG. 8 shows an embodiment wherein the bearing reinforcement comprising a plurality of stacked reinforcing plates which cover decreasing angular sectors.

PREFERRED EMBODIMENT OF THE INVENTION

(12) The present invention refers to a wind turbine comprising at least a pitch bearing (1) comprising at least two rings (4, 5), preferably an outer ring (4) and an inner ring (5), each of the at least two rings (4, 5) attached to a wind turbine component (2, 3), being a first wind turbine component a blade (2) and a second wind turbine component a hub (3), and further comprising at least one bearing reinforcement (6) attached to at least one of the two rings (4, 5).

(13) The essential feature of the wind turbine of the invention is that it comprises at least one bearing reinforcement (6) which is attached to at least to one of the two rings (4, 5) of the pitch bearing (1) the at least one bearing reinforcement (6) comprising a bearing reinforcement thickness (RT) that is variable along a circumferential direction of the pitch bearing (1).

(14) This bearing reinforcement (6) thus provides the pitch bearing (1) with a smooth stiffness variation along its circumferential direction.

(15) Preferably, the at least one bearing reinforcement (6) is attached to the at least one of the two rings (4, 5) of the pitch bearing (1) such that the at least one of the two rings (4, 5) is disposed between the at least one bearing reinforcement (6) and the wind turbine component (2, 3) to which the at least one of the two rings (4, 5) is attached. In an embodiment, the at least one bearing reinforcement (6) is attached to the outer ring (4) of the pitch bearing (1), which is in turn attached to the hub (3), being the outer ring (4) disposed between the at least one bearing reinforcement (6) and the hub (3).

(16) In an embodiment, the at least one bearing reinforcement (6) is attached to at least to one of the two rings (4, 5) of the pitch bearing (1) on a location surface different than the surface of the pitch bearing (1) in contact with the blade (2) or with the hub (3).

(17) In an embodiment, the at least one bearing reinforcement (6) is attached to at least to one of the two rings (4, 5) of the pitch bearing (1) such that an intermediate component is disposed between the at least one of the two rings (4, 5) to which the at least one bearing reinforcement (6) is attached. In particular, in an embodiment of the invention, the at least one bearing reinforcement (6) is attached to the inner ring (5) of the pitch bearing (1) which is in turn attached to the blade (2), such that a pitch plate configured to drive the pitch bearing (1) is disposed between the at least one bearing reinforcement (6) and the inner ring (5).

(18) In an embodiment of the invention, the bearing reinforcement thickness (RT) is variable in a continuous manner in at least part of its longitudinal dimension. Therefore the strength distribution on the pitch bearing (1) decreases in a continuous manner. In another preferred embodiment, the bearing reinforcement thickness (RT) is variable in a discontinuous manner, such that step-like reinforcement thickness (RT) variations are provided along the longitudinal dimension of the bearing reinforcement. In FIG. 2, the bearing thickness (BT) and the variation of the bearing reinforcement thickness (RT) can be seen. As a result of the reinforcement thickness variation, the resultant thickness and hence the resultant stiffness of the bearing varies as required by the stresses distribution.

(19) In a further embodiment, the at least one bearing reinforcement (6) may have a continuous variation of the bearing reinforcement thickness (RT) of at least a part of the bearing reinforcement (6) in the circumferential direction of the pitch bearing (1).

(20) Preferably, the at least one bearing reinforcement (6) comprises a planar central part defined in the circumferential direction of the pitch bearing (1).

(21) In an embodiment, the length of the planar central part of the at least one bearing reinforcement (6) is similar to the longitudinal dimension of the at least one bearing reinforcement (6) measured in the circumferential direction of the pitch bearing (1), as can be seen in FIG. 2 or 4.

(22) In an embodiment of the invention, the at least one bearing reinforcement (6) is attached to at least one of the two rings (4, 5) such that the maximum bearing reinforcement thickness (RT) is located coinciding with an area of the pitch bearing (1) subjected to the highest stresses or deformations. Some examples of these embodiments can be seen in FIGS. 5 to 7.

(23) If the at least one bearing reinforcement (6) has a continuous variation of the bearing reinforcement thickness (RT) in the circumferential direction of the pitch bearing (1) (similar to a wedge and hence called wedged reinforcement), given that the at least one bearing reinforcement (6) is joined to the at least one of the two rings (4, 5) by bolts (8) usually parallel to the bearing axis (and thus not perpendicular to the reinforcement surface, at least in part of it), a special solution has to be found since a priori there is no a flat surface perpendicular to the bolts and hence the heads of the bolts do not properly match the support surface.

(24) A possible embodiment of the present invention, shown in FIG. 3c, solves the above described problem by providing the at least one bearing reinforcement (6) with a recess (11) in correspondence to each bolt hole to provide a flat support surface for the bolt (8) heads.

(25) Another solution is shown in FIG. 3d. In this case, there is at least a counter-wedge (9) on the superior surface of the bearing reinforcement (6) with a continuous thickness variation to obtain a flat support for the bolt (8) head.

(26) In a preferred embodiment, the at least one bearing reinforcement (6) comprises a flat surface disposed in contact with at least one of the two rings (4, 5), for example, in contact with the outer ring (4), and a flat opposing surface obliquus to the surface disposed in contact with the outer ring (4), such that the bearing reinforcement thickness (RT) varies with a constant slope towards the the planar central part where the maximum bearing reinforcement thickness of the bearing reinforcement (6) is reached. In such a case, preferably the counter-wedges have a surface with the same slope than the flat opposing surface obliquus to the surface disposed in contact with the outer ring and a flat surface perpendicular to the bolts axis. In an exemplary embodiment of the invention, a plurality of counter-wedges (9) is used, in the form of washer, in correspondence with each bolt hole.

(27) In FIG. 4 a preferred embodiment of the bearing reinforcement (6) can be appreciated. Preferably, the at least one bearing reinforcement (6) comprises at least two reinforcing plates (10) stacked such that the resultant bearing reinforcement thickness (RT) is variable along the circumferential direction of the pitch bearing (1), i.e. non-constant. In this case, the at least one bearing reinforcement (6) comprises a plurality of stacked reinforcing plates (10).

(28) In an embodiment, the at least one bearing reinforcement (6) comprises at least two stacked reinforcing plates (10) each one having a different longitudinal dimension extending along a different angular sector over the pitch bearing (1).

(29) In FIG. 8 a bearing reinforcement (6) comprising a plurality of stacked reinforcing plates (10) is represented. As can be seen in the FIG. 8, those staked reinforcing plates (10) have different longitudinal dimensions thus extending through angular sectors of different sizes.

(30) Preferably, one of the staked reinforcing plates (10) is in contact with one of the two rings (4, 5) of the pitch bearing (1) and the longitudinal dimension of the staked reinforcing plate (10) in contact with one of the two rings (4, 5) of the pitch bearing (1) is greater than the longitudinal dimension of the at least other stacked reinforcing plate (10) such that it extends along a greater angular sector over the pitch bearing (1). This embodiment allows a gradual stiffness transition along the circumferential direction of the bearing reinforcement (6), but providing a cost effective solution, as it can be achieved by planar plates, cheaper to manufacture than the wedged reinforcement. In FIGS. 5 and 6 two possible embodiments of the bearing reinforcement (6) comprising staked reinforcing plates (10) with this configuration are represented.

(31) In FIG. 8, the bearing reinforcement (6) comprises a plurality of staked reinforcing plates (10) which cover decreasing angular sectors of the at least one of the two rings (4, 5), in this case, the outer ring (4) of the pitch bearing (1). In that figure an example in which the largest stacked reinforcing plate (10) corresponds to an angular sector of 60° can be appreciated. In the same figure there are represented other stacked reinforcing plates (10) as for example the one corresponding to an angular sector of 35°, this being stacked over the largest stacked reinforcing plate (10).

(32) This embodiment allows having a higher stiffness in the critical zone. At the ends of the bearing reinforcement (6) only a few reinforcing plates (10) are stacked, hence providing there a minimum bearing reinforcement thickness (RT), for a smooth stiffness transition from the outer ring (4) area without bearing reinforcement (6). For example, in this embodiment, just two stacked reinforcing plates (10) extend all over the length of the bearing reinforcement (6) while four stacked reinforcing plates (10) extend in the central part, hence achieving there the maximum thickness.

(33) In an exemplary embodiment of the invention, the bearing reinforcement thickness (RT) is variable from its ends towards its center along the circumferential direction of the pitch bearing (1). The bearing reinforcement thickness (RT) can be greater in the centre, Also, the bearing reinforcement thickness (RT) variation can be symmetrical.

(34) Also, in an embodiment, the stacked reinforcing plates (10) can have the same thickness, as for example in the embodiment of FIG. 4. In said figure different cross sections of said bearing reinforcement (6) can be appreciated (sections AA, BB, CC). Said different cross sections are variable in height in a discontinuous manner from the ends to the center in the circumferential direction of the pitch bearing (1), i.e. the bearing reinforcement (6) has a variable bearing reinforcement thickness (RT).

(35) In an embodiment of the invention, shown in FIG. 5, the pitch bearing (1) is a rolling element bearing, preferably a ball bearing or a roller bearing, and the bearing reinforcement (6) is placed in a section of one of the two rings (4, 5) near to the position of an orifice (12) for the insertion of the rolling element.

(36) In a double raceway rolling element bearing (with a first raceway closer to the blade (2) and a second raceway closer to the hub (3)) there are two orifices for the insertion of the rolling elements in the outer ring (4) of the pitch bearing (1), which are placed opposite to each other. In these cases, the wind turbine comprises at least two bearing reinforcements (6) which are placed near those orifices of the pitch bearing (1). Particularly the at least two bearing reinforcements (6) are centered in the section of introduction of the rolling elements in the pitch bearing (1).

(37) As can be seen in said FIG. 5, the positions for the introduction of the rolling elements are considered to be at 90° and 270°. The 0° has been selected to point the section of the pitch bearing (1) that is closer to the main shaft of the wind turbine and 180° is the section of the bearing closer to wind turbine nose.

(38) In an alternative embodiment shown in FIG. 6 there is only one bearing reinforcement (6) placed at an angle of 55°. In another example two bearing reinforcements (6) placed at 55° and 235° respectively are provided.

(39) The bearing reinforcements (6) can be placed also in other critical sections of the pitch bearing (1) as for example over a sector placed between the 90° and the 180° positions. In FIG. 7 can be shown an embodiment in which the pitch bearing (1) is reinforced with a plurality of bearing reinforcements (6) close to each other.

(40) In a preferred embodiment the ratio between the maximum bearing reinforcement thickness (RT) and the bearing thickness (BT) is at least 15%, more preferably at least 25%

(41) Another preferential feature is that a width of the at least one bearing reinforcement (6) is substantially equal to a width of the at least one of the two rings (4, 5) to which the at least one bearing reinforcement (6) is attached.

(42) In another embodiment, the outer ring (4) is attached to the hub (3), wherein the at least one bearing reinforcement (6) is attached to a planar surface of the outer ring (4) opposite to planar surface closer to the hub (3).

(43) Consequently, the proposed wind turbine comprises at least one bearing reinforcement (6) which allows the pitch bearing (1) transferring the stresses in an even smoother way than the pitch bearings (1) of the state of the art.