A METHOD AND A SYSTEM FOR MOUNTING A ROTOR TO A DRIVE SHAFT OF A WIND TURBINE

Abstract

A method for mounting a rotor to a drive shaft of a wind turbine, the method comprising placing a hub on a surface, attaching a first, a second, and a third rotor blade to the hub to thereby make a rotor in situ. To protect the blades and to avoid fixed lifting lugs on the rotor, the method includes the step of wrapping a sling about each of the blades, attaching each sling to a fitting, lifting each fitting to thereby raise the rotor from the surface, and attaching the rotor to the drive shaft while the position and orientation of the rotor is controlled by the slings.

Claims

1. A method for mounting a rotor to a drive shaft of a wind turbine, the method comprising placing a hub on a surface, attaching a first, a second, and a third rotor blade to the hub to thereby make a rotor in situ, wrapping a sling about each of the blades, attaching each sling to a fitting, lifting each fitting to thereby raise the rotor from the surface, and attaching the rotor to the drive shaft while the position and orientation of the rotor is controlled by the slings.

2. The method according to claim 1, wherein at least one of the slings is wrapped more than 360 degrees about a rotor blade.

3. The method according to claim 1, wherein the orientation of the rotor is controlled by changing the distance from the fitting to one of the rotor blades which thereby becomes a controlled rotor blade.

4. The method according to claim 3, wherein the distance from the fitting to the controlled rotor blade is changed by changing the distance between the fitting and that sling which is wrapped about the controlled blade, the sling thereby becoming a controlled sling.

5. The method according to claim 3, wherein the distance is changed by use of a power driven actuator.

6. The method according to claim 1, wherein at least one sling is attached to the fitting via a pulley block.

7. The method according to claim 5 wherein the power driven actuator is attached between the fitting and the pulley block of the controlled sling.

8. The method according to claim 4, wherein the rotor is protected against contact with the controlled sling by a shield (18) which is removed from the rotor when the rotor is mounted to the drive shaft.

9. The method according to claim 8, wherein the shield is held by the controlled sling.

10. The method according to claim 1, wherein all slings are attached to a single fitting.

11. The method according to claim 1, wherein all slings are assembled in one point where they are attached to the fitting.

12. The method according to claim 1, wherein the rotor forms a flange for attachment to the drive shaft and thereby defines a rotor axis about which the rotor is configured to rotate when attached to the drive shaft, and where the rotor is carried by a stand on the surface such that the flange is lifted from the surface.

13. The method according to claim 4, wherein the controlled sling is wrapped one turn about the controlled blade and the other slings are wrapped two turns about the corresponding blades.

14. The method according to claim 4, wherein the controlled sling is connected to an actuator without a pulley block and the other slings are connected to the fitting via a pulley block.

15. A system for mounting a rotor to a drive shaft of a wind turbine, the system comprising at least three slings each being suitable for being wrapped about a blade, a fitting for attaching the slings to a crane cable, and an actuator for changing the distance between the fitting and one of the slings to thereby enable controlling of the orientation of a rotor which is lifted by a sling about each blade.

16. The system according to claim 14, further comprising a shield which is attachable to the rotor or to one of the slings and which is suitable for protecting the rotor against contact with a sling.

17. The system according to claim 16, wherein the shield forms a curved track for receiving one of the slings during reorientation of the rotor.

Description

DETAILED DESCRIPTION OF THE DRAWINGS

[0030] The invention will now be described in further details with reference to the accompanying drawings, wherein:

[0031] FIG. 1 illustrates a wind turbine with a tower and a nacelle;

[0032] FIG. 2 illustrates a rotor placed on ground in a stand ready to be lifted;

[0033] FIG. 3 illustrates the rotor when lifted free from the stand;

[0034] FIG. 4 illustrates the step of reorienting the rotor by use of an actuator extending the distance from the fitting to the controlled blade;

[0035] FIG. 5 illustrates the rotor in an orientation ready for attachment to a drive shaft; and

[0036] FIG. 6 illustrates an embodiment of the controlled sling.

[0037] Further scope of applicability of the present invention will become apparent from the following detailed description and specific examples. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

[0038] FIG. 1 illustrates a wind turbine 1 with a tower 2, a nacelle 3, a rotor including three blades 4 and a hub covered with a spinner 5

[0039] FIG. 2 illustrates the rotor 6 of the wind turbine before it is attached to the drive shaft in the nacelle. The rotor comprises a hub covered by a spinner 5 and the three blades 4. The rotor is placed in a stand 7 on ground surface.

[0040] A first, second, and third sling 8, 9, 10 is wrapped about the blades. The slings are attached to a fitting, in this embodiment in the form of a lifting hook 11. Two of the slings are connected to the hook via robes 12, 13 and the pulley blocks 14, 15. The last sling 8, herein referred to as the controlled sling, is connected to the fitting via an actuator 16 and a robe 17.

[0041] Two of the slings 9, 10 are wrapped two turns around the corresponding blade, and the controlled sling 8 is wrapped only one turn about the controlled blade.

[0042] The system includes a shield 18 which protects against direct contact between the hub or the spinner and the slings, particularly the controlled sling 8. Typically, the hub is covered with a spinner having a smooth and aerodynamic appearance. The spinner is typically arranged directly against the hub. To protect the spinner, or to protect the hub, the shield is arranged against the outer surface of the hub or spinner and formed such that the controlled sling is guided by the shield and remains on the surface of the shield. The guiding may be insured by bended edges of the shield such that the shield forms a track between two edges, e.g. parallel edges, in which track the sling may contact the shield during reorientation of the rotor.

[0043] FIG. 3 illustrates when the rotor is lifted free from the stand. In this view, the orientation is not yet changed.

[0044] In FIG. 4, the orientation of the rotor is controlled by operation of the power driven actuator 16, thereby changing the distance from the fitting to the controlled rotor blade 4. The power driven actuator can be controlled by a controller which obtains orientation parameters from a sensor, e.g. a gyro, and by which a desired orientation can be selected. The actuator 16 may be operated simultaneously with the lifting of the rotor.

[0045] When the rotor is tilted, the shield protects the hub or a spinner attached to the hub. The shield forms bended edges 19, 20 holding the slings along the centre track of the shield and thus preventing the controlled sling 8 from sliding away from the shield.

[0046] The shield is held by the sling at the points 21, 22 where the sling penetrates through holes in the shield.

[0047] FIG. 5 illustrates the rotor in an orientation ready for attachment to the drive shaft in the nacelle.

[0048] FIG. 6 illustrates an embodiment where the controlled sling 8 is held by a spreader structure. The spreader structure comprises a lifting yoke 23 with pulley blocks 24. The controlled sling runs through the pulley blocks 24 and through the eyelets 25 at the lower carry beam 26. The yoke and lower carry beam maintains a distance between the rights and left sides 27, 28 of the controlled sling, and thereby protects the controlled blade. Particularly, the spinner, and/or the hub may enter into the open window 29 formed between the right and left sides 27, 28 of the controlled sling. Accordingly, the shield which protects the spinner from contact with the sling is not necessary.

[0049] I one embodiment, the spreader structure is combined with the protective shield, and in one embodiment, the protective shield is suspended by the sling within the window 29.

[0050] The actuator 16 may, as illustrated be arranged above the yoke, or alternatively, it can be arranged between the yoke and the lower carry beam to thereby increase or decrease the length of the open window 29.

[0051] In this embodiment, the controlled sling 8 could be in two distinct sections, e.g. formed by two separate robes, or belts, where one of the two distinct sections connect to the lifting yoke 23 and pulley blocks 24 and optionally to the lower carry beam 26, and the other one of the two distinct sections connect to the lower carry beam only.

[0052] In one embodiment, the yoke and the lower carry beam is formed in one piece, e.g. in the form of a frame of 4 steel bars joined to form a quadrangular shape. In another embodiment, the spreader structure is constituted by or comprises a ring shaped, e.g. a circular structure, e.g. made of steel, and arranged to receive the spinner or hub during reorientation of the rotor.

[0053] FIGS. 7 and 8 illustrate an alternative embodiment in which the controlled sling 8 is held by a single spreader 30. The spreader forms an eyelets 31 in which the controlled blade is carried and it allows the spinner to be received into the eyelet when the rotor is rotated. The length of the single spreader 30 may e.g. correspond at least to the diameter of the spinner at the cross section where the blades are attached. Accordingly, the shield which protects the spinner from contact with the sling is not necessary.