HUB FOR A WIND TURBINE, WIND TURBINE AND METHOD FOR UP-GRADING A HUB OF A WIND TURBINE

Abstract

A hub for a wind turbine which includes a hub body having a first blade bearing flange, a second blade bearing flange and a main bearing flange, and a stiffening structure stiffening a first portion of the hub body, wherein the first portion is arranged adjacent to the main bearing flange and between the first blade bearing flange and the second blade bearing flange. This hub has the advantage that a stiffness (or a rigidity) of the hub body can be increased close to the main bearing flange.

Claims

1. A hub for a wind turbine, comprising: a hub body having a first blade bearing flange, a second blade bearing flange, and a main bearing flange; and a stiffening structure stiffening a first portion of the hub body, wherein the first portion is arranged adjacent to the main bearing flange and between the first blade bearing flange and the second blade bearing flange.

2. The hub according to claim 1, wherein the stiffening structure comprises a rib formed integrally with the hub body.

3. The hub according to claim 1, wherein the hub body comprises a second portion, the second portion being arranged adjacent to the main bearing flange and between the first blade bearing flange and the second blade bearing flange, further wherein the first blade bearing flange or the second blade bearing flange is arranged between the first portion and the second portion, and the stiffening structure connects the first portion and the second portion.

4. The hub according to claim 3, wherein the stiffening structure spans from the first portion to the second portion such that an opening is formed between the stiffening structure and the hub body.

5. The hub according to claim 4, wherein the hub body comprises a third blade bearing flange and a third portion, the third portion being arranged adjacent to the main bearing flange and between the first blade bearing flange and the third blade bearing flange, further wherein at least one of the first blade bearing flange, the second blade bearing flange, and the third blade bearing flange is arranged between the first portion and the third portion and at least one other of the first blade bearing flange, the second blade bearing flange, and the third blade bearing flange is arranged between the second portion and the third portion, and the stiffening structure has a Y-shape connected to the hub body at the first portion, the second portion, and the third portion.

6. The hub according to claim 1, wherein the stiffening structure is arranged inside the hub body.

7. The hub according to claim 1, wherein the stiffening structure comprises at least two reinforcing elements joined to each other.

8. The hub according to claim 1, wherein the stiffening structure comprises at least one manhole.

9. The hub according to claim 1, wherein the main bearing flange has a diameter of at least two meters.

10. The hub according to claim 1, wherein the hub body is made from cast iron.

11. A wind turbine comprising a hub according to claim 1.

12. The wind turbine according to claim 11, wherein the wind turbine is a direct drive wind turbine.

13. A method for upgrading a hub of a wind turbine, wherein a stiffening structure is joined to a hub body of the hub, the hub body comprising a first blade bearing flange, a second blade bearing flange, and a main bearing flange, for stiffening a first portion of the hub body, the first portion being arranged adjacent to the main bearing flange and between the first blade bearing flange and the second blade bearing flange.

Description

BRIEF DESCRIPTION

[0046] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0047] FIG. 1 depicts a schematic view of a first example of a hub;

[0048] FIG. 2 depicts a schematic view of a second example of a hub;

[0049] FIG. 3 depicts a schematic view of a third example of a hub; and

[0050] FIG. 4 depicts a schematic view of an example of a wind turbine.

[0051] In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

DETAILED DESCRIPTION

[0052] FIG. 1 shows a schematic view of a first example of a hub 100 for a wind turbine 200 (see FIG. 4). In this first example, the hub 100 has a hub body 110 with a first blade bearing flange 120, a second blade bearing flange 120 and one main bearing flange 130. Thus, this hub 100 is configured for carrying two blades 204 (see FIG. 4).

[0053] For example, the main bearing flange 130 has a diameter of 4.5 m and the first and second blade bearing flanges 120 each have a diameter of 4 m. For example, the hub body 110 is made from cast iron. In order to provide a sufficient stiffness or rigidity of the hub 100, particularly close to the main bearing flange 130, without massively increasing a material thickness of the hub body 110, two stiffening structures 140 are provided. In this example, the stiffening structures 140 are implemented integrally as a rib in the hub body 110. The ribs 140 are arranged at positions of the hub body 110 in a first portion 112 and in a second portion 114. Both the first portion 112 and the second portion 114 are arranged adjacent to the main bearing flange 130 and between the first blade bearing flange 120 and the second blade bearing 120. The first portion 112 and the second portion 114 are facing each other across the main bearing flange 130.

[0054] Implementing the stiffening structures 140 as shown in this example increases the stiffness of the hub body 110 particularly in the first portion 112 and in the second portion 114. Thus, the stiffness around a circumference of the main bearing flange 130 can be equalized or levelled this way. Therefore, a main bearing (not shown) can have an increased service life compared to the case where no such stiffening structures 140 are used.

[0055] FIG. 2 shows a schematic view of a second example of a hub 100 for a wind turbine 200 (see FIG. 4). The hub 100 has a hub body 110 with one main bearing flange 130 and three blade bearing flanges 120, a first, a second and a third blade bearing flange 120. The blade bearing flanges 120 are arranged symmetrically around a rotational symmetry axis of the main bearing flange 130. The hub body 110 has three portions 112, 114, 116 having a relatively low stiffness. For example, the first portion 112 is arranged between the first blade bearing flange 120 and the second blade bearing flange 120, the second portion 114 is arranged between the second blade bearing flange 120 and the third blade bearing flange 120, and the third portion 116 is arranged between the third blade bearing flange 120 and the first blade bearing flange 120. Further, each of the first, second and third portion 112, 114, 116 is arranged adjacent to the main bearing flange 130.

[0056] In order to increase the stiffness of these portions 112, 114, 116 and to equalize the stiffness on a circumference around the main bearing flange 130, a stiffening structure 140 is arranged in the hub body 110. Here, the stiffening structure 140 consists of a Y-shaped plate made from steel. The shape may also be described as an equilateral triangle form with each side being curved towards a symmetry point of the triangle. By using this shape, three openings 145 are formed between the plate 140 and the hub body 110, through which the main bearing flange 130 or a main bearing mounted there can be accessed. The plate 140 further has a centrally arranged man hole 144, which reduces the weight of the plate 140 and allows further access to the inside of the hub body 110 for servicing.

[0057] In this example, the plate 140 is bolted to the hub body 110 using a number of bolts 146 (only one bolt 146 is designated with a reference numeral for better overview). The plate 140 may comprise a specific bolting section (not shown) and the hub body 110 may comprise a corresponding specific bolting section (not shown) for bolting the plate 140 to the hub body 110. The plate 140 connects and spans between the first, second and third portion 112, 114, 116 of the hub body 110. Thus, a stress or strain that acts or is applied to one of the first, second or third portion 112, 114, 116 will alike act on the plate 140 and be transferred by the plate 140 to the respective other two portions. Therefore, the hub body 110 cannot be deformed in the first portion 112, second portion 114 or third portion 116 individually, but only by involving the respective other portions.

[0058] FIG. 3 shows a schematic view of a third example of a hub 100 for a wind turbine 200 (see FIG. 4). The hub 100 comprises a hub body 110 which is similar to the hub body 110 of the hub 100 described with reference to FIG. 2. However, in this example, the stiffening structure 140 comprises three reinforcing elements 142. The reinforcing elements 142 each have the same shape. The reinforcing elements 142 are made from a composite material which has a very high stiffness-to-weight ratio, such that the reinforcing elements 142 are relatively light but can still transfer high tensile or compressive forces. Each one of the reinforcing elements 142 spans between and connects two of the first portion 112, second portion 114 or third portion 116. The reinforcing elements 142 are fixed to the hub body 110 at the respective positions by using bolts 146. Using these smaller reinforcing elements 142 makes it a lot easier to install them and mount them to the hub body 110.

[0059] Further, in order to increase the stiffness gain obtained by using the reinforcing elements 142, each two reinforcing elements 142 are joined with each other in a neighboring section. In this example, the reinforcing elements 142 are joined by means of joining plates 143, which are bolted by bolts 146 (only one bolt 146 is designated with a reference numeral) to the respective reinforcing element 142. This allows transfer of tensile or compressive forces between the reinforcing elements 142.

[0060] Together, the three reinforcing elements 142 form a shape that is similar to the Y-shaped plate 140 described with reference to FIG. 2.

[0061] The reinforcing elements 142 may have shapes that are different to what is shown in this example, such as rod-like, formed as a strut or spoke or the like.

[0062] FIG. 4 shows a schematic view of an example of a wind turbine 200. The wind turbine 200 comprises a tower 202 on which a rotor comprising a hub 100 and three blades 204 is arranged. For example, the hub 100 has the features of the hub 100 described with reference to FIG. 2 or FIG. 3. The wind turbine 200 is implemented as a direct drive wind turbine. For example, the rotor of the wind turbine 200 has a diameter of over 100 m. However, by using the hub 100 as described before, larger diameters can be realized easily because the hub body's 110 (see FIGS. 1-3) stiffness may be increased selectively in portions that have a relatively low stiffness by using a stiffening structure 140. The wind turbine 200 may be used both on-shore as well as off-shore.

[0063] Although the present embodiment has been described in accordance with the exemplary 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.

[0064] 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