Arrangement and method to rotate the hub of a wind turbine

Abstract

An arrangement and a method of rotating a hub of a wind turbine are provided. A wind turbine includes a hub mounted to a nacelle, whereby the hub is rotatable around an axis of rotation in respect to the nacelle. A rotor blade is arranged at the hub that leads to a torque around the axis of rotation of the hub. A counter weight is attached to the hub, whereby the counter weight has a mass that leads to a counter-torque around the axis of rotation. The counter-torque interacts with the torque during the installation of a second rotor blade to the hub. The counter weight is mounted to the hub by a mechanical arrangement that is rotatable in respect to the hub around the axis of rotation of the hub. The mechanical arrangement and the counter weight are rotatable in respect to the hub into a certain predetermined position.

Claims

1. A wind turbine, comprising: a hub mounted to a nacelle, wherein the hub is rotatable with respect to the nacelle around an axis of rotation of the hub, a first rotor blade arranged at the hub, wherein the first rotor blade leads to a torque around the axis of rotation of the hub, a counter weight mounted to the hub by a lever that is rotatable with respect to the hub around the axis of rotation so that the lever and the counter weight are rotatable with respect to the hub into a predetermined position, wherein the lever is mounted at the axis of rotation of the hub; and whereby the counter weight is adapted to provide a counter-torque around the axis of rotation of the hub, wherein the counter-torque reduces the torque of the first rotor blade.

2. The wind turbine according to claim 1, wherein the counter weight is arranged such that the counter-torque facilitates a rotation of the hub into a predefined position which is used for arranging the second rotor blade to the hub.

3. The wind turbine according to claim 1, wherein the counter-torque of the counter weight at least partially compensates the torque of the first rotor blade attached to the hub.

4. The wind turbine according to claim 1, wherein the counter weight is mounted to the hub via the lever such that the counter weight is moveable along an axis towards and away from the axis of rotation of the hub.

5. The wind turbine according to claim 1, wherein the counter weight is movable along the lever.

6. The wind turbine according to claim 5, wherein the counter weight is movable with respect to the hub such that the counter weight is movable along an axis towards and away from the axis of rotation of the hub.

7. The wind turbine according to claim 1, wherein the counter weight and the lever are detachable from the hub after installation of the first rotor blade and the second rotor blade.

8. A method for use with a wind turbine, comprising: mounting a hub of the wind turbine to a nacelle, wherein the hub is rotatable with respect to the nacelle around an axis of rotation of the hub, arranging a first rotor blade at the hub, wherein the first rotor blade leads to a torque around the axis of rotation, arranging a counter weight to the hub via a lever, wherein a mass of the counter-weight leads to a counter-torque around the axis of rotation, wherein the counter-torque interacts with the torque during installation of a second rotor blade to the hub, wherein the lever is mounted at the axis of rotation the hub, and rotating the counter weight and the lever around the axis of rotation of the hub with respect to the hub into a predetermined position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a view of a hub and nacelle in accordance with an embodiment of the disclosure.

(2) FIG. 2 shows a wind turbine during installation.

(3) FIG. 3 shows a wind turbine with the lever and the counterweight.

(4) FIG. 4 shows a wind turbine during installation of a first rotor blade.

(5) FIG. 5 shows a wind turbine during installation of the rotor blades.

(6) FIG. 6 shows a wind turbine during installation of a second rotor blade.

(7) FIG. 7 shows a wind turbine during installation of the rotor blades.

(8) FIG. 8 shows a wind turbine during the installation of a third rotor blade.

(9) FIG. 9 shows a wind turbine after the installation of the rotor blades.

(10) FIG. 10 shows a view of a hub and nacelle in accordance with another embodiment of the disclosure.

(11) FIG. 11 shows the second embodiment in use.

DETAILED DESCRIPTION OF INVENTION

(12) FIG. 1 shows a nacelle 2 of a wind turbine. Attached to the nacelle 2 is a hub 3 that is prepared to receive rotor blades mounted to the hub 3. A rotor blade may be mounted to a designated spot 4a, for example. Attached to the front of the hub 3 is a lever 5 which points outward in radial direction seen in respect to the axis of rotation 10 of the wind turbine hub 3.

(13) The lever 5 may be rotated around the axis of rotation 10 of the hub 3 in respect to the hub 3. The lever 5 is detachably mounted to the hub 3 of the wind turbine. The lever 5 may be mounted to the hub 3 before the installation of the first rotor blade and may be detached from the hub 3 after the installation of the rotor blades.

(14) Attached to the lever 5 is a counter weight 6. The counter weight 6 is movable along the lever 5. A distance between the center of mass of the counter weight 6 and the axis of rotation 10 of the hub 3 may be set to a certain predetermined distance. Thus the weight of the counter weight 6 will result in a certain predetermined torque at the hub 3. The torque depends on the position of the counter weight 6 along the lever 5, and the position of the lever 5 in respect to the hub 3.

(15) FIG. 2 shows a wind turbine during installation. A nacelle 2 is installed on a tower 1. Attached to the nacelle 2 is a hub 3. The hub 3 shows several spots 4a, 4b, 4c where rotor blades will be mounted. FIG. 2 shows three places 4a, 4b, 4c for rotor blades.

(16) FIG. 3 shows a wind turbine with the lever and the counterweight. FIG. 3 shows the wind turbine of FIG. 2. In addition, a lever 5 and a counter weight 6 are attached at the front of the hub 3. The front side of the hub 3 is the side which may be covered with the spinner nose later during the installation.

(17) The hub 3 is rotated into a first position to allow the installation of a first rotor blade. In this case the spot to mount a first rotor blade 4a is arranged in a way that the rotor blade can be attached mainly horizontally.

(18) The lever 5 is rotated in respect to the hub 3 in a way that is pointing away from the spot to attach a first rotor blade. In this case the lever 5 is pointing mainly horizontally away from the spot 4a. The counter weight 6 is arranged with its center of mass close to the axis of rotation of the hub 3. As there is no rotor blade attached to the hub 3 yet, no torque from the counter weight 6 is needed to compensate the torque of the rotor blade.

(19) FIG. 4 shows a wind turbine during installation of a first rotor blade 7a. FIG. 4 shows the wind turbine of FIG. 3. In addition, a first rotor blade 7a is attached to the hub 3 at the spot 4a.

(20) The rotor blade 7a is lifted by a crane 8 and a lifting device 9. The crane 8 adjusts the first rotor blade 7a in a way that the attachment points at the rotor blade 7a align with their counter parts at the hub 3. Then the first rotor blade 7a is attached to the hub 3.

(21) The counter weight 6 stays close to the axis of rotation of the hub 3, as long as the weight of the first rotor blade 7a is still carried by the lifting device 9 and the crane 8.

(22) FIG. 5 shows a wind turbine during installation of the rotor blades. FIG. 5 shows the wind turbine during the installation of the first rotor blade 7a as seen in FIG. 4. In FIG. 5, the crane 8 and the lifting device 9 (see FIG. 4) are detached from the first rotor blade 7a, so the weight of the first rotor blade 7a is now carried by the hub 3. The weight of the rotor blade 7a leads to a torque at the hub 3 of the wind turbine.

(23) The counter weight 6 is now moved along the lever 5 outward, away from the axis of rotation of the hub 3, to increase the torque of the counter weight 6 at the hub 3. Thus the torque of the counter weight 6 compensates at least a part of the torque of the first rotor blade 7a acting on the hub 3.

(24) To install a second rotor blade, the hub 3 needs to be rotated into a second position. The rotation of the hub 3 is shown by the arrow in the FIG. 5.

(25) The torque of the first rotor blade 7a and the torque of the counter weight 6 at least partially compensate each other. Thus the load at the drive, turning the hub 3 around its axis of rotation, is smaller then without the counter weight 6.

(26) The counter weight 6 may also be moved further out along the lever 5 so that the torque of the counter weight 6 is bigger than the torque of the first rotor blade 7a. Thus the torque of the first rotor blade 7a is over-compensated by the torque of the counter weight 6 and the hub 3 of the wind turbine may be rotated around its axis of rotation without the need of a drive. The hub 3 may be rotated by the help of gravity at the counter weight 6.

(27) FIG. 6 shows a wind turbine during installation of a second rotor blade 7b.

(28) FIG. 6 shows the wind turbine as shown in FIG. 5 during the installation of rotor blades. The hub 3 of the wind turbine is now turned into a second position, where a second rotor blade 7b is installed at a spot 4b.

(29) The crane 8 and the lifting device 9 lift a second rotor blade 7b up to the hub 3. The rotor blade 7b is attached to the hub 3 at the spot 4b.

(30) After the crane 8 and the lifting device 9 are removed from the second rotor blade 7b the lever 5 is arranged into a certain predetermined position in respect to the rotor blades 7a and 7b. The counter weight 6 is adjusted to a second distance from the hub 3 along the lever 5, so that the torque of the counter weight 6 can at least partially compensates the resulting torque of the first and the second rotor blade 7a and 7b.

(31) FIG. 7 shows a wind turbine during installation of the rotor blades. The hub 3 of the wind turbine is, together with the first and the second rotor blades 7a and 7b and the counter weight 6 at the lever 5, rotated into a third position around the axis of rotation of the hub 3. The rotation is illustrated in FIG. 7 by the arrow.

(32) After the hub 3 has been rotated into the third position, the third rotor blade is being installed to the hub 3 at the spot 4c.

(33) The torque of the counter weight 6 at the lever 5 compensates at least a part of the resulting torque of the rotor blades 7a and 7b. Thus the load at the drive that is turning the hub 3 is minimized.

(34) The torque of the rotor blades 7a and 7b may be overcompensated by the counter weight 6. The hub 3 can then be rotated by the help of gravity.

(35) FIG. 8 shows a wind turbine during the installation of a third rotor blade 7c. The hub 3 has been rotated into a third position suitable to install the third rotor blade 7c.

(36) The third rotor blade 7c is lifted by help of the crane 8 and the lifting device 9 up to the spot 4c. The rotor blade 7c is attached to the hub 3 at the spot 4c.

(37) When the lifting device 9 and the crane 8 are removed from the rotor blade 7c, the hub 3 carries the load of the rotor blade 7c. The torque of the rotor blade 7c compensates at least partially the torque of the two rotor blades 7a and 7b.

(38) Thus, the counter weight 6 and the lever 5 are no longer needed. The counter weight 6 is moved along the lever 5 towards the axis of rotation of the hub 3. Thus the torque of the counter weight 6 is minimized.

(39) After the installation of the rotor blades 7a, 7b and 7c is finished, the counter weight 6 and the lever 5 are detached from the hub 3 of the wind turbine. This may be done by the help of the crane 8.

(40) FIG. 9 shows a wind turbine after the installation of the rotor blades 7a, 7b and 7c. FIG. 9 shows the wind turbine after the installation of all three rotor blades 7a, 7b and 7c. The counter weight and the lever have been removed from the wind turbine.

(41) FIG. 10 shows a second embodiment. FIG. 10 shows a wind turbine with a nacelle 2 and a hub 3. The hub 3 is prepared to receive three rotor blades at the spots 4a, 4b and 4c.

(42) A rotor blade 7a is lifted by a lifting device 9 and a crane 8. The rotor blade 7a is to be mounted to the spot 4a at the hub 3. At the hub 3, a first cantilever 11 is attached with its first end. The second end of the first cantilever 11 is attached to a first end of a second cantilever 11 by a pivot joint 12. A counter weight 6 is attached to the second end of the second cantilever 11.

(43) The angle between the cantilevers 11 is mainly 0 degree at the pivot joint 12. Thus the center of the mass of the counter weight 6 is close to the axis of rotation of the hub.

(44) The distance between the axis of rotation of the hub 3 and the center of the mass of the counter weight 6 may be increased by increasing the angle between the cantilevers 11.

(45) FIG. 11 shows the second embodiment in use. FIG. 11 shows the wind turbine of FIG. 10 with the cantilevers 11 and the counterweight 6 attached to the hub 3.

(46) The rotor blade 7a is attached to the hub 3 at the spot 4a. The lifting device 9 and the crane 8 are removed.

(47) The weight of the rotor blade 7a leads to a torque at the hub 3. To compensate the torque of the rotor blade 7a the angle between the cantilevers 11 is increased at the pivot joint 12. Thus, the distance between the center of the mass of the counter weight 6 and the axis of rotation of the hub 3 increases. Thus the torque at the hub 3 caused by the counter weight 6 increases.

(48) The cantilevers 11 are adjusted in a way that the counter weight 6 is now on the other side of the hub 3 then the rotor blade 7a. Thus the torque of the counter weight 6 at least partially compensates the torque of the rotor blade 7a. The hub 3 can now be rotated into a second position to install a second rotor blade. The rotation is illustrated by the arrow in FIG. 11.

(49) The drive used for the rotation of the hub 3 needs less power, as the load at the hub due to the rotor blade 7a is compensated by the counter weight 6.

(50) The torque of the rotor blade 7a may be over-compensated by the counter weight 6. Thus the rotation of the hub 3 is started without the help of a drive.

(51) While specific embodiments have been described in detail, those with ordinary skill in the art will appreciate that various modifications and alternative to those details could be developed in light of the overall teachings of the disclosure. For example, elements described in association with different embodiments may be combined. Accordingly, the particular arrangements disclosed are meant to be illustrative only and should not be construed as limiting the scope of the claims or disclosure, which are to be given the full breadth of the appended claims, and any and all equivalents thereof. It should be noted that the term “comprising” does not exclude other elements or steps and the use of articles “a” or “an” does not exclude a plurality.