Lightweight non-resonant stator support

[0002] The present invention relates to a wind turbine having a generator with stator and rotor in a machine housing that is disposed at the top of the wind turbine tower, wherein the stator has a support construction comprising a plurality of support arms. The generator of the wind turbine is a ring generator.

[0003] Wind turbines are known and are already used in large numbers. The development of wind turbines is tending towards greater generator output. This trend is often accompanied by an increase in the dimensions of the separate components (especially their support arms) and hence their mass.

[0004] Today's prior art, as shown in FIG. 1, has a wind turbine 1 whose nacelle 2 weight (machine housing weight) is in the order of 90-100 tons. Part of this weight is that of the stator support 12 to which the stator 20 of the generator is mounted. Such prior art includes blades 3 coupled to a rotor 4. The rotor 4 has connected thereto an electrical rotor system 5 for generating electricity in interaction with the stator 20 in a manner well known in the art. The wind turbine is thus composed of a relatively large mass. However, such large masses are difficult to handle and generate considerable stress on both the tower and the tower foundations, leading not only to increased material stress, but also to greater costs for the separate, aforementioned components of a wind turbine. Reference is made by way of illustration to the fact that the nacelles (that is, the machine housing) of the wind turbine are not only transported to the building site, but in many cases must be hoisted in their separate parts to the top of the tower.

[0005] Another problem encountered with wind turbines relating above all, in addition to building law issues, to the acceptance of such turbines among the respective neighborhood, is that of noise emission, in that the noise emissions produced even by modern wind turbines constitute a disturbance and can therefore reduce the acceptance of such turbines.

[0006] Part of the noise emissions are generated by the support arms, since these have a hollow interior and sealed outer surfaces, with the result that a resonant body is formed.

[0007] One object of the present invention is therefore to specify a wind turbine whose components have reduced weight and whose noise emissions are lowered.

[0008] This object is achieved in accordance with the invention by the stator support having an open structure. This open structure results in reduced weight, on the one hand, as well as less material being used, on the other. Noise emissions are also reduced, because by virtue of their open structure the support arms can no longer form a resonant body, thus eliminating the noise emission of the support arms, at least.

[0009] Due to its lower weight compared to previous designs, a stator support according to the invention thus helps to reduce the mass of the nacelle, and hence to improve handling and transportability of the components and/or the entire nacelle.

[0010] Other preferred embodiments are characterized by the subclaims.

[0011] One embodiment shall now be described in detail with reference to the figures. These show:

[0012] FIG. 1 shows the nacelle portion of a wind turbine 1 according to the prior art;

[0013] FIG. 2 is a side elevation view of a support arm according to the invention; and

[0014] FIG. 3 is a front view of a stator support according to the invention, with a plurality of support arms.

[0015] The support arm 12 shown in a side elevation view in FIG. 2 has an open structure, with the result that it does not form a resonant body. Ascending from a base 18 of support arm, a plurality of holes 22 can be seen in support arm 12, such that the structure of the support arm is formed by lateral bars 24 and traverse struts (traverses) 26 therebetween. Hence, support arm 12 does not constitute a resonant body and cannot, therefore, emit noise.

[0016] The support arm 12 pursuant to the invention extends from base 18 along a predefined stretch that ensues from the size of the stator 20 attached to said support arm 12. At the end of the support arm 12 opposite base 18, a perpendicular displacement member 16 extends perpendicularly to support arm 12 and has a support plate 17 at the end of said perpendicular displacement member 16. A stator 20 is mounted on said support plate 17. Stator windings 28 are inside the stator 20. A rotor portion 5 is adjacent the stator. The support plate 17 may have a larger area than the cross-sectional area of a perpendicular displacement member 16.

[0017] In the embodiment of support arm 12 according to the invention as shown in FIG. 2, the depth (i.e., the horizontal extension in the figure) is constant. Alternatively, however, said depth can vary and thus permit a change in the cross-section of the support arm 12 of the invention.

[0018] FIG. 3 shows a plan view of a stator support 10 comprised of a plurality of support arms 12 pursuant to the invention. In the figure, one can well see the open, lattice-like structure of support arms 12 formed by bars 24 and traverse members 26.

[0019] Support arms 12 thus have an open structure and form, with their inwardly oriented bases 18, an opening through which a rotor axis (a rotor spigot) can extend. Support arms 12 can be used as single elements in that regard. Alternatively, support arms 12 can be joined together, for example at their bases 18, to form an integral stator support 10 or a plurality of stator support segments, which for their part can be deployed singly, or joined together to form an integral stator support 10.

[0020] The radially and outwardly directed end of each support arm 12 is divided into two extension arms 14. The outer, perpendicularly angled member 16 of each extension arm 14 runs axially parallel to the direction of the rotor axis. The area of the support plate 17 to which the stator is attached is greater than the cross-sectional area of beam member 16.

[0021] The cross-section of extension arm 14 decreases in size from base 18 of the arm to its outer end, namely as it extends outward to the perpendicular member 16. In the case of a support arm 12 as present in the embodiment shown here, this change in cross-section results, given that the depth (i.e., the horizontal extension of the support arms 12 in FIG. 2) remains constant, from the decreasing width (horizontal extension of the support arms 12 in FIG. 3), especially in extension arm 14. Alternatively, the depth and width of support arm 12 and member 16 according to the invention may vary.

[0022] In order to illustrate application of the invention, a portion of stator 20 is shown in its installed state, by way of example. Stator 20 extends in a ring shape over the entire outer periphery of the stator support 10 and is distanced from said stator support by the amount that support plate 17 is distanced from the extension arm 14 by member 16. Substantial weight is therefore saved.

[0023] In one embodiment of the invention, support arms 12 are attached either singly, as segments or as an integral stator support 10 to a sub-construction which for its part is firmly attached to the machine house.

[0024] From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.