WIND TURBINE DESCENT SYSTEM

Abstract

The present invention provides a wind turbine comprising a tower, a nacelle, and a descent module configured to accommodate at least one person while descending down at least a portion of a height of the tower, wherein the descent module is arranged to be magnetically attracted to the tower to guide the descent module relative to the tower over at least a portion of the descent. The present invention also provides a descent module for a wind turbine, and a method of lowering at least one person down at least a portion of a height of a tower of a wind turbine.

Claims

1. A wind turbine comprising a tower, a nacelle, and a descent module configured to accommodate at least one person while descending down at least a portion of a height of the tower, wherein the descent module is arranged to be magnetically attracted to the tower to guide the descent module relative to the tower over at least a portion of the descent.

2. The wind turbine according to claim 1, wherein the descent module comprises a plurality of tower engaging elements arranged to engage at least a portion of the tower over at least a portion of the descent.

3. The wind turbine according to claim 2, wherein the tower engaging elements are arranged to pivot in use in order to follow the shape of the tower over the descent.

4. The wind turbine according to claim 2, wherein the tower engaging elements are wheels that are arranged to engage and roll along at least a portion of the tower over at least a portion of the descent.

5. The wind turbine according to claim 1 4, wherein the descent module comprises at least one magnet arranged to attract at least one magnetic component of the tower to thereby guide the descent module relative to the tower over at least a portion of the descent.

6. The wind turbine according to claim 5 wherein the magnet(s) are provided at one or more intermediate locations between the plurality of tower engaging elements of the descent module, and/or wherein the magnet(s) are provided at one or more locations adjacent to one or more of the tower engaging elements of the descent module.

7. The wind turbine according to claim 5, wherein the magnet(s) are comprised in one or more of the tower engaging elements of the descent module.

8. The wind turbine according to claim 1 wherein the wind turbine further comprises an external access system located towards a top of the tower, and at least partially outside the nacelle and the tower, from which at least one person may enter the descent module.

9. The wind turbine according to claim 8, wherein the descent module is located at least partially within the external access system when in its initial position before the start of a descent.

10. The wind turbine according to claim 8, wherein the descent module is releasably mounted to the external access system and/or to the tower when in its initial position before the start of a descent.

11. The wind turbine according to claim 1 wherein the descent module is arranged to be accessed directly from the nacelle or directly from the tower.

12. The wind turbine according to claim 1, wherein the wind turbine further comprises a lowering mechanism for controlling the speed of descent of the descent module.

13. The wind turbine according to claim 12, wherein the lowering mechanism is mounted to the tower or to the nacelle and comprises a cable that is attached to or arranged to be attached to the descent module.

14. The wind turbine according to claim 12, wherein the lowering mechanism is additionally operable to lift the descent module up the tower.

15. The wind turbine according to claim 1, wherein said descent module is designed for accommodating a plurality of people, such as at least two, at least three or at least four people.

16. The wind turbine according to claim 1, wherein said descent module is designed for accommodating at least one person on a stretcher.

17. The wind turbine according to claim 1, wherein said descent module comprises manual input means, e.g. a handle, a knob or the like, which is designed for activating releasing means for providing a release from said position at said upper level.

18. The wind turbine according to claim 1, wherein said descent module is an essentially closed structure having an entrance, e.g. a door, a hatch or the like, for at least one person.

19. The wind turbine according to claim 1, wherein said descent module is configured to protect said one or more persons inside the descent module, e.g. from fire and/or thermal hazards, from impact from e.g. falling objects, debris and the like.

20. The wind turbine according to claim 1, wherein said descent module is designed in such a manner that, when it is located at said position at the nacelle of the wind turbine, at least one person can enter the descent module, for example from the top of the nacelle or via a door, hatch or the like in the nacelle.

21. The wind turbine according to claim 1, wherein the emergency system is configured as a retro-fit system or as built-in system.

22. A descent module configured to accommodate at least one person while descending down at least a portion of a height of a tower of a wind turbine, the descent module comprising at least one magnet for magnetically attracting the descent module to a tower of a wind turbine to guide the descent module relative to the tower over at least a portion of a descent.

23. The descent module according to claim 22, wherein said descent module is an essentially closed structure having an entrance, e.g. a door, a hatch or the like, for at least one person.

24. A method of lowering at least one person down at least a portion of a height of a tower of a wind turbine, the method comprising: accommodating at least one person in a descent module; lowering the descent module down at least a portion of the height of the tower; and magnetically attracting the descent module to the tower to guide the descent module relative to the tower over at least a portion of the descent.

25. A method of performing an emergency exit from an upper level of a wind turbine according to claim 1, whereby at least one person located at an upper level, e.g. in or on the nacelle, in or at the upper level of the wind turbine tower, or the like, enters the descent module, said at least one person activates releasing means of the descent module, whereby the descent module is released from its position at the nacelle and descends down at least a portion of a height of the tower, wherein the descent module is arranged to be magnetically attracted to the tower to guide the descent module relative to the tower over at least a portion of the descent.

26. The method according to claim 25, wherein said descent module is configured to protect said one or more persons inside the descent module, e.g. from fire and/or thermal hazards, from impact from e.g. falling objects, debris and the like, and wherein said one or more persons can stay inside the descent module after it has reached the lower level, e.g. until rescue personnel reaches the wind turbine location.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The invention will now be described in detail with reference to the accompanying drawings, in which:

[0056] FIG. 1 schematically illustrates a wind turbine comprising a descent module in accordance with one possible embodiment of the present invention;

[0057] FIG. 2 schematically illustrates the top portion of the wind turbine of FIG. 1;

[0058] FIG. 3 schematically illustrates the descent module of the wind turbine of FIG. 1;

[0059] FIG. 4 schematically illustrates a plan view of the descent module of the wind turbine of FIG. 1;

[0060] FIGS. 5a and 5b schematically illustrate a wheel including magnets that may be used in an alternative embodiment of the invention; and

[0061] FIG. 6 schematically illustrates the top portion of a wind turbine according to an alternative embodiment of the present invention.

DETAILED DESCRIPTION

[0062] FIG. 1 schematically illustrates a wind turbine 1 according to one possible embodiment of the present invention. FIGS. 2 to 4 schematically illustrate specific portions of the wind turbine, as described in more detail below.

[0063] The wind turbine is an on-shore wind turbine (although the invention may equally be applied to an off-shore wind turbine). The wind turbine 1 comprises a tower 2, a nacelle 3 rotatably coupled top the top of the tower, and a rotor 4 including a plurality of blades coupled to the nacelle. The rotor 4 is connected to an electrical generator housed within the nacelle 3 by a drivetrain. The tower has 2 a generally circular cross-section and widens towards its base. The tower 2 is substantially formed of steel panels or sections.

[0064] The interior of the tower 2 may be accessed via a lower door 6 in the tower. The tower 2 further comprises an internal lift system 7 which may be accessed via the lower door 6, and which extends into the nacelle 3 to provide direct access to the nacelle. The internal lift system 7 may be used for transporting one or more people (such as engineers or mechanics) to or from the top of the wind turbine 1.

[0065] The wind turbine further comprises a descent module 10 for allowing people to descend from the top of the wind turbine 1 to the base of the tower 2 in an emergency. The descent module is most clearly illustrated in FIG. 2 (which shows an enlarged view of the top of the tower 2) and FIGS. 3 and 4 (which show the descent module in perspective view and plan view respectively). The descent module 10 comprises an enclosed cage 12 providing a chamber 11 that is arranged to comfortably receive and carry a plurality of people during a descent from the top of the wind turbine 1 to the base of the tower 2. The chamber 11 may also be arranged to carry at least one person on a stretcher. The chamber 11 may be accessed via a door provided in a sidewall of the cage 12. In other embodiments the chamber may have solid walls and/or may be at least partially open.

[0066] The wind turbine 1 further comprises an external access system 8 (most clearly illustrated in FIG. 2) that is located towards the top of the tower 2 and below the nacelle 3.The descent module 10 may be entered from the external access system 8 when the descent module 10 is in its initial position before the start of a descent, as illustrated in FIG. 2. The external access system 8 is located outside the tower 2 and the nacelle 3, and comprises an enclosed cage extending circumferentially around the tower 2 that provides a walkway from which the descent module 10 may be entered. In other embodiments the external access system may have solid walls and/or may be at least partially open, and may not extend around the entire circumference of the tower.

[0067] The walkway is accessible from the nacelle 3 through a door 9 provided in a floor of the nacelle 3 that opens to the external access system 8. The schematic illustration of FIG. 2 only shows a single door 9 in the floor off the nacelle 3. However, it is preferable to include a plurality of doors 9 through which the walkway can be accessed in the nacelle 3 so that the walkway can be accessed from several different positions inside the nacelle, and so that the walkway can be accessed directly from the nacelle even if one of the doors is blocked. In addition, the walkway is accessible from inside the top of the tower 2 through at least one further door 9a provided towards the top of the tower that opens to the external access system 8.

[0068] The external access system 8 is attached to the tower 2, for example by bolts or welded joints, and remains fixed relative to the tower 2 as the nacelle 3 rotates during operation of the wind turbine 1.

[0069] When not in use, the descent module 10 is located within the cage of the external access system 8, as shown in the schematic illustrations of FIGS. 1 and 2, although in other embodiments at least a portion of the descent module 10 may protrude from the external access system 8. In this initial position, the descent module 10 is releasably mounted to the tower 2 and/or the to the external access system 8 by a releasable retaining mechanism. The releasable retaining mechanism may, for example, comprise one or more releasable latches.

[0070] The descent module 10 comprises a tower-facing wall 15 provided by the cage 12. As shown in the schematic illustrations of FIGS. 3 and 4, the tower-facing wall 15 has a concave shape that is arranged to fit around the curved shape of the tower 2 during a descent. The descent module 10 further comprises four sets of wheels 16a, 16b, 16c, 16d arranged at the four corners of the tower-facing wall 15 in a substantially square configuration, as shown in the schematic illustration of FIG. 3. Each set of wheels 16a, 16b, 16c, 16d comprises a pair of rubber wheels each having a substantially flat radially outer surface. The wheels 16a, 16b, 16c, 16d are arranged to directly engage and roll along the outer surface of the tower 2 during a descent, as described in more detail below. Each set of wheels 16a, 16b, 16c, 16d is mounted to the cage 12 of the descent module 10 via a mounting component that is arranged to pivot about a substantially vertical axis in use in order to allow the wheels to remain in contact with the tower 2 and follow the shape of the tower over a descent. In the present embodiment the wheels 16a, 16b, 16c, 16d are maintained in contact with the outer surface of the tower even when the descent module is in its initial position prior to use, although in other embodiments the wheels may be brought into contact with the outer surface of the tower only after a decent has been initiated.

[0071] The descent module 10 further comprises first and second magnets 20a, 20b arranged respectively at each side of the tower-facing wall 15, as shown in the schematic illustrations of FIGS. 3 and 4. Each of the first and second magnets is fixed relative to the cage 12, and is disposed between and located adjacent to one of the upper sets of wheels 16a, 16b and one of the lower sets of wheels 16c, 16d. The magnets 20a, 20b are arranged to attract the descent module 10 to the steel sheets or segments forming the tower 2 in order to guide the descent module relative to the tower during a descent, as described in more detail below. In order to maximise their effect, the magnets 20a, 20b are arranged to be as close to the outer surface of the tower 2 as is practical without directly engaging the outer surface of the tower during a descent.

[0072] The magnets 20a, 20b are permanent magnets, although electromagnets could equally be used. The magnets 20a, 20b may, for example, be alnico magnets or hard ferrite magnets. Each one of the magnets 20a, 20b may take the form of a single magnet, or may comprise a plurality of individual magnet elements.

[0073] The wind turbine 1 further comprises a lowering mechanism 21 for lowering (and in some embodiments raising) the descent module 10 from the top of the wind turbine 1 to the base of the tower 2. The lowering mechanism 21 is arranged to control the speed of the descent module 10 during a descent. The lowering mechanism comprises a winch drum 22 that is attached to the tower 2 (or alternatively to the access system 8), and carries at least one cable 23 that is attached to (or at least attachable to) the cage 12 of the descent module 10.

[0074] Electronic control elements (or alternatively mechanical control elements) are provided both within the descent module 10 and at another location in the wind turbine 1 outside the descent module in order to control operation of the descent module, for example to initiate a descent.

[0075] The descent module 10 and/or the external access system 8 may form part of the wind turbine 1 as originally designed and built, or may alternatively have been retro-fitted to the wind turbine (even if the wind turbine was not originally designed to include a descent module or an external access system for a descent module).

[0076] Operation of the descent module 10 will now be described.

[0077] When it is desired to lower one or more people from the top of the wind turbine 1 in an emergency situation in which it is impossible or at least undesirable to use the internal lift system 7, the one or more people to be evacuated from the top of the wind turbine may enter the walkway provided in the external access system 8 via the door 9 (or one of the doors) provided in the floor of the nacelle 3. From there, the one or more people may enter the chamber 11 of the descent module 10 through the door provided in the cage 12 of the descent module 10. Once the one or more people are located inside the chamber 11 of the descent module 10, one of the control elements may be operated (either from inside the descent module by one of the people in the descent module or from outside the descent module by an operator outside the descent module) to release the descent module 10 from the tower and/or the external access system and initiate the descent.

[0078] Once the descent has been initiated, the descent module 10 begins to descend from the top of the wind turbine 1 under the action of gravity. During the descent, the wheels 16a, 16b, 16c, 16d roll along the outer surface of the tower 2, and the magnets 20a, 20b comprised in the descent module 10 act to attract the descent module to the steel panels or sections forming the tower 2. In this way, the descent module 10 is guided relative to the tower 2, with the magnets 20a, 20b helping to ensure the descent module is safely and reliably controlled during its descent. The guiding effect of the magnets 20a, 20b is maximised by arranging the magnets to be as close as is practical to the outer surface of the tower 2 during the descent, as described above. The descent module is shown at an intermediate point of its descent at 10a in the schematic illustration of FIG. 1.

[0079] The speed of the descent is controlled by the lowering mechanism 21.

[0080] By attracting the magnets 20a, 20b of the descent module 10 to structural components of the tower 2, the guiding functionality provided by the magnets may be achieved without the addition of any further magnetic components in the tower specifically for the purpose of attracting the descent module. Similarly, by arranging the wheels 16a, 16b, 16c, 16d to roll along the outer surface of the main body of the tower 2 it is possible to control the movement of the descent module 10 without the addition of any further mechanical components in the tower specifically for the purpose of engaging the descent module.

[0081] As the descent module is lowered down the tower on the cables 23, each set of wheels 16a, 16b, 16c, 16d is allowed to pivot about its pivot axis in order to allow the wheels to remain in normal contact with the outer surface of the tower 2 and follow the widening shape of the tower over the descent.

[0082] When the descent module 10 reaches the base of the tower 2 at the end of its descent, as indicated at 10b in the schematic illustration of FIG. 1, the door of the descent module may then be opened to allow the one or more people to exit the descent module.

[0083] In this way the one or more people may be evacuated from the top of the wind turbine 1 to the base of the wind turbine.

[0084] After use of the descent module 10, it needs to be returned to the top of the tower if the wind turbine is to be used again. In some embodiments, the lowering mechanism 21 may be operated in reverse to return the descent module to its initial position. Alternatively, the lowering mechanism is intended only to lower the descent module, and an external winch or the like should be used for this purpose. This provides a saving on the strength and design of the lowering mechanism, which is most likely worth it considering the limited number of times the descent module is expected to be in use. The magnets 20a, 20b also act to guide the descent module 10 over the upper part of its ascent. Once the descent module 10 has returned to its initial position near to the top of the tower 2, the retaining mechanism may then be reengaged in order to retain the descent module in its initial position ready for further use.

[0085] In the above-described embodiment, the tower 2 is formed of steel panels or sections over substantially its entire height, and so the descent module is attracted to the tower over substantially the entire descent without any requirement for further magnetic components specifically for the purpose of attracting the descent module. However, in other embodiments, at least a portion of the tower 2 may be formed of a non-magnetic material. For example, in another embodiment, the tower 2 may comprise a lower portion that is formed of concrete panels or sections and an upper portion that is formed of steel panels or sections. In this case the descent module may be attracted to the tower only over an upper portion of its descent (corresponding to the magnetic portion of the tower), and the action of gravity and the outer surface of the tower may be sufficient to guide the descent module over a lower portion of its descent. Alternatively, one or more additional magnetic components may be provided in or on the non-magnetic portion of the tower specifically for the purpose of attracting the descent module. In this case the descent module may still be attracted to the tower over portions of its height that are generally formed of non-magnetic materials.

[0086] In the above-described embodiment, two magnets are provided in the descent module, with each magnet extending between an upper set of wheels and a lower set of wheels. However, in other embodiments the number of magnets and the location of the magnets may be different. For example, one or more magnets may be provided at a central location on the tower-facing wall of the descent module in between the sets of wheels, or four individual magnets may be provided adjacent to (either to the side of or behind) each set of wheels.

[0087] Alternatively or in addition to any of the magnet arrangement described above, it is also possible for one or more magnets to be provided in one or more of the wheels (or alternatively other tower engaging elements) of the descent module. For example, FIGS. 5a and 5b schematically illustrate a wheel 100 that may be used in a descent module as described above. The wheel comprises a plurality of magnets 101 arranged around its circumference and embedded within a main body, which may be formed of rubber. When wheels 100 of this type are fitted to the descent module, the wheels themselves magnetically attract the magnetic components of the tower during a descent to thereby attract the descent module to the tower.

[0088] As an alternative to including one or more magnets in the descent module, it is also possible to provide at least one magnet, and preferably a track of magnets, in the tower, the magnets acting to attract one or more magnetic components of the descent module (for example steel components of the descent module) to thereby guide the descent module during a descent.

[0089] In the above-described embodiment, the external access system is attached to the tower. However, in other embodiments the external access system could alternatively be attached to the nacelle. In addition, the descent module could alternatively be located below or to the side of (instead of within) the external access system when in its initial position.

[0090] In the above-described embodiment, the descent module is arranged to be entered from an external access system. However, the external access system is not required in all embodiments, and the descent module may alternatively be arranged to be entered directly from the nacelle, or directly from the tower. For example, FIG. 6 schematically illustrates an alternative embodiment in which the descent module 10 is located at least partially within the nacelle 3 when in its initial position. In this alternative embodiment the descent module may be lowered down the wind turbine on a cable 23 that is attached to a structural part of the nacelle 3 (such as the skeleton beam).

[0091] In the above-described embodiment, the descent module is provided in addition to an internal lift system within the tower, and is intended for use only in emergency situations. However, in other embodiments the descent module may instead provide the primary (and possible only) system for ascending the wind turbine and/or descending from the wind turbine.

[0092] It will be appreciated that many other modifications and variations are also possible within the scope of the appended claims.