Wind turbine

Abstract

Provided is a wind turbine including a hub and several blades rotatably attached to the hub by means of blade bearings including an inner ring coupled with the respective blade and an outer ring coupled with the hub, or vice versa, and rolling elements provided between the rings, wherein the outer ring or the inner ring has a cross section with a circumferentially varying thickness.

Claims

1. A wind turbine comprising: a hub; a plurality of blades rotatably attached to the hub by means of blade bearings comprising an inner ring coupled with a respective blade and an outer ring coupled with the hub, or vice versa, and rolling elements provided between the inner ring and the outer ring, wherein the outer ring or the inner ring has a cross section with a circumferentially varying thickness; wherein the outer ring or the inner ring is arranged such that a section with a largest thickness is positioned towards a front side of the hub and a section with a smallest thickness is positioned towards a rear side of the hub.

2. The wind turbine according to claim 1, wherein the circumferentially varying thickness varies continuously between a maximum thickness and a minimum thickness.

3. The wind turbine according to claim 1, wherein the hub comprises an attachment area with a surface having a geometry corresponding to an attachment side surface of the outer ring or the inner ring.

4. A bearing for a wind turbine for attaching a blade to a hub, comprising: an inner ring to be attached to the blade; and an outer ring to be attached to the hub, or vice versa, with rolling elements being provided between the inner ring and the outer ring; wherein the outer ring or the inner ring has a cross section with a circumferentially varying thickness; wherein the outer ring or the inner ring is arranged such that a section with a largest thickness is positioned towards a front side of the hub and a section with a smallest thickness is positioned towards a rear side of the hub.

5. The bearing according to claim 4, wherein the circumferentially varying thickness varies continuously between a maximum and a minimum thickness.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with references to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows a schematic partial view of a wind turbine with an embodiment of a blade bearing;

(3) FIG. 2 shows a cross sectional view along the line II-II in FIG. 1

(4) FIG. 3 shows a cross sectional view along the line III-III in FIG. 1; and

(5) FIG. 4 shows a principal sketch of an outer ring of an alternative embodiment of a blade bearing.

DETAILED DESCRIPTION

(6) FIG. 1 shows a partial view of an inventive wind turbine 1 comprising an inventive blade bearing 2. FIG. 1 shows the hub 3 and a main shaft 4 transferring the rotation of the hub to a not shown power generator.

(7) Usually the hub 3 comprises three blades which are attached to the hub by means of respective blade bearings 2 allowing the respective blade to be pitched if need be.

(8) Each blade bearing 2 comprises an outer ring 5, in this example attached to the hub 3 and an inner ring 6 to which the blade is attached. The attachment area respectively the bearing area is shown in the respective cross sections shown in FIGS. 2 and 3. As these figures depict the outer ring 5 is attached to the hub 3 by means of respective bolts 7 extending through respective bores 8, 9 provided in the outer ring 5 and the hub 3. The side surface 10 of the outer ring 5 rests on a respective attachment area surface 11 of the hub 3.

(9) The inner ring 6 is also attached by means of respective bolts 12 to the blade 13, of which only the blade root 14 is shown.

(10) As FIGS. 2 and 3 show respective roller elements 15 are provided between the outer ring 5 and the inner ring 6 running on respective raceways and allowing the rotation of the inner ring 6 relative to the not rotating outer ring 5, allowing the pitching of the blade 13.

(11) As FIG. 1 shows the thickness of the outer ring 5 varies circumferentially. In a first region 16 the thickness of the outer ring 5 is smaller or shows a minimum thickness value. At the opposite side in the region 17 the thickness of the outer ring 5 is clearly larger and shows a maximum value. The minimum thickness in the region 16 is shown with the thickness d in FIG. 2, while the maximum thickness in the region 17 is shown with the thickness D in FIG. 3. As FIG. 1 clearly shows the region 17 is positioned at the front end of the hub towards the wind direction W, while the section 16 with the smaller thickness is directed towards the opposite side.

(12) As FIG. 1 shows the region 16 with the small thickness may extend for about 180. Then the thickness increases constantly to a maximum value. It is certainly also possible that the region 16 is smaller, so that the increase of the thickness may directly start at the minimum thickness position and increase constantly to the maximum thickness position at the opposite side of the outer ring 5.

(13) The FIGS. 2 and 3 show respective cross sections taken along the lines II-II (FIG. 2) and III-III (FIG. 3).

(14) As a comparison between FIGS. 2 and 3 clearly shows, the outer ring 5 shown in cross section has a varying thickness. The ring thickness is almost double the size at the region 17, compared to the region 16. This varying cross section allows the bearing to be sufficiently stiffed to support itself in the region which needs to be stiffened, i.e. at the front side of the hub while the bearing respectively the outer ring is thin enough where the hub is stiff enough and the load resting on this arrangement is lower.

(15) As FIGS. 2 and 3 show also the hub geometry is chosen corresponding to the geometry of the outer ring 5. As a comparison of FIGS. 2 and 3 show also the attachment area surface 11 of the hub 3 shows a varying geometry, which in its extension corresponds to the geometry or extension of the outer ring 5, so that there is also a corresponding surface attachment between these two items.

(16) Finally, as FIGS. 2 and 3 also show that the inner ring 6 has a constant thickness.

(17) While, as depicted above, FIG. 1 shows an outer ring with a first section 16 extending for approximately 180 having the small constant thickness d, which then increases constantly in the section 17 to the maximum value D, FIG. 4 shows alternative embodiment of an outer ring of an inventive blade bearing 2. This outer ring is characterised in that the thickness of the ring 5 increases constantly along the circumference from the minimum value d to the maximum value D at the opposite ring side.

(18) Independently of specific geometry of the outer ring 5 the above-mentioned makeups of the different versions of the outer ring 5 can be easily produced by means of current forging techniques. The respective outer ring 5 may be a one-piece ring or may be a segmented ring comprise several separate ring segments.

(19) Alternatively, the inner ring can show the varying thickness. Further the attachment of the rings to the hub and the blade can be vice versa.

(20) 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.

(21) 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.