WO2010083837A2

WO2010083837A2 - A gripping apparatus for handling and/or servicing components of a wind turbine, and a method and a wind turbine tower therefore

Info

Publication number: WO2010083837A2
Application number: PCT/DK2010/050009
Authority: WO
Inventors: Jesper Staerke Rosengren; Jonas Kristensen
Original assignee: Vestas Wind Systems A/S
Priority date: 2009-01-20
Filing date: 2010-01-20
Publication date: 2010-07-29
Also published as: WO2010083837A3

Abstract

The invention relates to a method of and a gripping apparatus for handling and/or servicing components of a wind turbine, such as installing and/or dismantling components into or from a wind turbine nacelle or such as servicing exterior components such as blades, hub, tower and nacelle of the wind turbine. The gripping apparatus has at least two gripping members capable of being attached to at least one of the following parts of the wind turbine: an attachment point of the nacelle frame, an attachment point of a bottom frame of the nacelle, or an attachment point at the outer circumference of the wind turbine tower. The at least two gripping members are capable of being attached one above the other to the wind turbine for forming an attachment of an external equipment to the wind turbine tower, when the external equipment is in a position of use.

Description

A GRIPPING APPARATUS FOR HANDLING AND/OR SERVICING COMPONENTS OF A WIND TURBINE, AND A METHOD AND A WIND TURBINE TOWER THEREFORE

FIELD OF THE INVENTION

The invention relates to a method of handling and/or servicing components of a wind turbine, such as installing and/or dismantling components into or from a wind turbine nacelle or such as servicing exterior components such as blades, hub, tower and nacelle of the wind turbine. The invention also relates to a gripping apparatus for installing or dismantling components into or from a wind turbine nacelle. Furthermore, the invention relates to a wind turbine tower comprising a gripping apparatus and to a wind turbine comprising a gripping apparatus.

BACKGROUND OF THE INVENTION

Cranes for handling such as installing and dismantling of components of a wind turbine nacelle and cranes for handling and/or servicing outer components of the wind turbine are often provided as a stationary part or an intermediate part of the nacelle as such. The components of the nacelle may be any component. The major components of the nacelle are the generator, the gear box if such is provided and a transformer if such is provided. Possibly also a main shaft and bearings may be major components of the nacelle. The outer components of the wind turbine may be the blades, the hub, the nacelle itself and the tower.

Other solutions of cranes have been proposed, where the cranes do not form part of the nacelle as such, and where the cranes are capable of being attached to the wind turbine tower.

EP 139150 discloses a working platform capable of being hoisted from the ground to the top of the wind turbine tower along a cable. A rig is initially installed at the top of the wind turbine tower and the working platform is subsequently hoisted thereto. The rig may be attached by bolts in an otherwise non-disclosed manner. WO 2004/092577 discloses a method of servicing the outer components of a wind turbine such as the wind turbine blades and the tower with a work platform. The method comprises the steps of positioning the work platform at the wind turbine tower and connecting the work platform to an upper part of the wind turbine with at least one cable. Furthermore the method comprises the steps of raising the work platform with the cable and cable winding means to a position of use, and holding the work platform to the side of the wind turbine tower with holding means. The invention also relates to a work platform for servicing the outer components of a wind turbine. The work platform is held in position of use by being suspended from the cables and is only intended for servicing outer components of the wind turbine, mainly for servicing the blades.

SUMMARY OF THE INVENTION

It may be seen as an object of the present invention to reduce the time needed for installing and for dismantling a crane for a wind turbine. It may also be seen as an object of the present invention to reduce the costs for installing and for dismantling a crane for a wind turbine. It may furthermore be seen as an object to reduce the costs for manufacturing a crane for a wind turbine. It may even further be seen as an object to increase the safety when working with a crane of wind turbine and/or when working on a work platform of a crane for a wind turbine. It may still even further be seen as an object of the present invention to provide a method and a work platform capable of being used for different sized wind turbine towers, said towers differing in circumferential shape and size.

The object of the invention may be obtained by a method comprising the step of

- holding the external equipment onto a side wall of the wind turbine tower by use of at least two gripping members, the one gripping member being positioned in a distance above the other gripping member,

- each of said at least two gripping members being attached to at least one of the following parts of the wind turbine: an attachment point of the nacelle frame, an attachment point of a bottom frame of the nacelle, or an attachment point at the outer circumference of the wind turbine tower, - each of said at least two gripping members capable of supporting the external equipment forming an attachment of the external equipment to the wind turbine.

Attachment of either one of the mentioned attachment points has the advantage that the attachment point is readily accessible from the outside of the wind turbine and that no special apparatus for attaching the external equipment need to be provided at the wind turbine before hoisting the equipment.

Other advantages are that the attachment points are provided in elements of an already installed wind turbine, i.e. the nacelle frame, a bottom frame or a tower of the wind turbine and that the attachment points may be provided in one or more of the wind turbine elements prior to installing the wind turbine itself.

According to a possible aspect of the method of the invention, the method comprises the further step of

- each of said at least two gripping members constituting a fixed member of the external equipment, and

- each of said at least two gripping members being extended through and being secured to an attachment point being a hole in the outer circumference of the wind turbine when the external equipment is in a position of use.

The attachment point being a hole in the wind turbine tower has the advantage that the attachment point is readily provided in the wind turbine and that different gripping members may be used for the same attachment point of the wind turbine. A hole, and especially a hole in the wind turbine tower, is easy to use as the attachment point of the wind turbine in combination with possible different gripping members of the external equipment.

According to an alternative aspect of the method of the invention, the method comprises the further step of

- each of said at least gripping member being extended through and being secured to an attachment point in the bottom frame of the wind turbine, and inside the nacelle fuselage, when the external equipment is in a position of use. According to still an alternative aspect of the method of the invention, the method comprises the further step of

- each of said at least gripping member being extended through and being secured to an attachment point in the bottom frame of the wind turbine, and outside the nacelle fuselage, when the external equipment is in a position of use.

Attachment of the external equipment to the bottom frame of the wind turbine has the advantage of the equipment being attached to the very top of the wind turbine and the attachment being provided at a part of the wind turbine already designed for high loads such as the loads from the rotor.

Another advantages of the external equipment to the bottom frame of the wind turbine is that the nacelle, and thus the bottom frame, may be yawed to a position where the attachment points of the bottom frame are right above the preliminary position of the handling and/or servicing equipment at a lower part of the wind turbine, e.g. at the ground nearby the wind turbine.

Especially in the case where access to the lower part of the wind turbine is limited due to a service road leading to just one position in vicinity of the wind turbine or the site of installation limiting access such as the site being on very rough ground, it is a further advantage that the attachment points of the bottom frame, by yawing the nacelle, can be positioned vertically above the position of access.

The access point of the bottom frame may either be provided inside the nacelle fuselage or outside the nacelle fuselage. If the access point is positioned outside the fuselage, the access point is readily accessible from beneath the nacelle, but the access point is also more prone to damage during operation of the wind turbine. If the access point is positioned inside the fuselage, the access point must be accessed through an opening such as a hatch in the nacelle fuselage, but the access point is also less prone to damage during operation of the wind turbine. According to a first aspect of the gripping member used in connection with the method according to the invention, the method comprises the step of

- each of said at least two gripping members having a threaded part being extended entirely through an attachment point being a the hole in the outer circumference of the wind turbine tower, or a hole in the bottom frame, or a hole in the nacelle frame when the external equipment is in the position of use, and

- where each of said at least two gripping members are being secured to the wind turbine by a nut being brought in engagement with the threaded part from the inside of the wind turbine tower or the inside of the nacelle fuselage.

A gripping apparatus with a threaded part capable of being inserted into a hole of the wind turbine and a corresponding nut is also an aspect of the invention. Furthermore, a wind turbine tower and a wind turbine with a gripping apparatus with a threaded part inserted into a hole of the wind turbine and a corresponding nut is also an aspect of the invention.

Attaching and securing the external equipment by a threaded part being inserted into a hole from the outside of the wind turbine and a corresponding nut being tightened on the threaded part from the inside of the wind turbine is a reliable and safe attachment and securing of the equipment to the wind turbine.

According to a second aspect of the gripping member used in connection with the method according to the invention, the method comprises the step of

- each of said at least two gripping members having an expanding part being extended entirely through an attachment point being a hole in the outer circumference of the wind turbine tower, or a hole in the bottom frame, or a hole in the nacelle frame when the external equipment is in the position of use, and

- where each of said at least two gripping members are being secured to the wind turbine tower by an expansion taking place inside of the wind turbine when the expansion part has been extended through the hole,

- said expansion resulting in the expansion part obtaining a larger circumference than the a circumference of the hole in the wind turbine tower or the hole of the nacelle frame. A gripping apparatus with an expandable part capable of being inserted into a hole of the wind turbine is also an aspect of the invention. Furthermore, a wind turbine tower and a wind turbine with a gripping apparatus with an expandable part inserted into a hole of the wind turbine is also an aspect of the invention.

Attaching and securing the external equipment by an expandable part of the gripping member being inserted into a hole from the outside of the wind turbine is a reliable and fast attachment and securing of the equipment to the wind turbine. It may be even be possible to expand the expandable part by using a tool from the outside of the wind turbine, not necessitating handling of any part of the gripping member from the inside the wind turbine.

According to a second aspect of the gripping member used in connection with the method according to the invention, the method comprises the step of - each of said at least two gripping members having a slotted part being extended entirely through an attachment point being a hole in the outer circumference of the wind turbine tower, or a hole in the bottom frame, or a hole in the nacelle frame when the external equipment is in the position of use, and - where each of said at least two gripping members are being secured to the wind turbine tower by a traverse element being brought in engagement with the slotted part from the inside of the wind turbine tower.

A gripping apparatus with a slotted part capable of being inserted into a hole of the wind turbine, and a corresponding traverse element is also an aspect of the invention. Furthermore, a wind turbine tower and a wind turbine with a gripping apparatus with a slotted part inserted into a hole of the wind turbine and a corresponding traverse part is also an aspect of the invention.

Attaching and securing the external equipment by a slotted part being inserted into a hole from the outside of the wind turbine and corresponding traverse element engaging the slotted part from the inside if the wind turbine is a reliable and fast attachment and securing of the equipment to the wind turbine.

According to a second aspect of the gripping member used in connection with the method according to the invention, the method comprises the step of - each of said at least two gripping members having a pin extended through an attachment point being a hole in the outer circumference of the wind turbine tower, or a hole in the bottom frame, or a hole in the nacelle frame, and

- said pin being limited from disengaging from the hole, when the external equipment is to be maintained in a position of use, and

- where the pin of each of said at least two gripping members are retracted from extension through the hole in the outer circumference of the wind turbine tower, or through the hole in the bottom frame, or through the hole in the nacelle frame, by allowing the pin to disengage from the hole, when the external equipment is to be released from the position of use.

A gripping apparatus with an extractable pin capable of being inserted into a hole of the wind turbine is also an aspect of the invention. Furthermore, a wind turbine tower and a wind turbine with a gripping apparatus with an extractable pin inserted into a hole of the wind turbine is also an aspect of the invention.

Attaching and securing the external equipment by an extractable pin of the gripping member being inserted into a hole from the outside of the wind turbine is a reliable and fast attachment and securing of the equipment to the wind turbine. It may be even be possible to insert the pin without necessitating handling of any part of the gripping member from the inside the wind turbine.

BRIEF DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Fig. 1 is an embodiment of a wind turbine tower section for gripping members according to the invention,

Fig. 2 is another embodiment of a wind turbine tower section for gripping members according to the invention,

Fig. 3 is a cross-section of a wind turbine tower with provisions for gripping members according to the invention,

Fig. 4 is a perspective view of a wind turbine nacelle frame and a wind turbine tower, both with provisions for gripping members according to the invention,

Fig. 5 is a first embodiment of a gripping member for a gripping apparatus according to the invention, Fig. 6 is a second embodiment of a gripping member for a gripping apparatus according to the invention,

Fig. 7 A and Fig. 7B is a perspective view of an embodiment of a wire suspension being part of the nacelle frame and being situated inside the nacelle fuselage, Fig. 8 is a perspective view of an embodiment of a wire suspension being part of the nacelle frame and being situated outside the nacelle fuselage, Fig. 9 is a perspective view of a truck for carrying a gripping apparatus together with other equipment for hoisting the gripping apparatus, Fig. 10 is a perspective view of an embodiment of a first wire suspension being lifted from the truck towards the tower and the nacelle of the wind turbine, Fig. 11 is a perspective view of the first wire suspension being in position underneath the nacelle and being secured to and suspended from a nacelle jib, Fig. 12 is a view of a wire winch of a truck, said wire winch being used during hoisting of the gripping apparatus from the truck towards the wind turbine tower.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Fig. 1 is a perspective view of a possible embodiment of a wind turbine tower section 1, preferably being integrated with the rest of the wind turbine tower, and with provisions for securing gripping members (see Fig. 5 and Fig. 6) for an external equipment to the tower section said external equipment being equipment for handling and/or servicing components, such as a generator, and possible internal equipment, such as an in-board crane, of the wind turbine as such.

Alternatively to the tower section being integrated with the rest of the wind turbine tower, the tower section may be separate from the rest of the wind turbine tower and intended for being slid around the outer circumference of the wind turbine tower. Most wind turbine towers are upwards conical. Thus, the dimension of the inner circumference of the tower section could be tuned in accordance with the dimension of the outer circumference of the wind turbine tower. Thereby, when the separate tower section is slid around the outer circumference of the wind turbine tower, the tower section stops sliding when the dimension of the inner circumference of the tower section matches the dimension of the outer circumference of the wind turbine tower. The tower section, integrated or separate, is provided with holes 2 extending substantially perpendicular to the circumference, i.e. radially in the embodiments shown. The holes 2 are provided along the circumference of the tower section. In the embodiment shown, holes 2 are provided two-and-two at six different locations along the circumference of the tower section 1.

The tower section 1 is provided with other holes 3 extending substantially parallel to generatrices of the tower section 1. The other holes 3 are intended for bolts (not shown) extending through the other holes 3. The bolts are otherwise intended for securing a yawing mechanism (not shown) to the top of the wind turbine tower.

Thus, the tower section 1 is inserted between a top flange (not shown) of the wind turbine tower and a mounting flange (not shown) of a yawing mechanism, or the tower section 1 is inserted between a top flange of one tower segment and a bottom flange of another tower segment placed above the one tower segment.

Singular holes, e.g. radial, or more holes than two, e.g. radial, may be provided at different locations. Also, more or less locations than six may be selected for the one or more holes 2 at each location. The number of holes and the number of locations along the circumference of the tower section 1 may vary depending on the equipment to be supported by the gripping members (see fig. 5 and Fig. 6) and depending on the construction and the function of the gripping members.

In the embodiment shown the tower section 1 is circular. Other shapes than circular, e.g. oval or polygonal, may be selected in stead of circular depending on the construction and the shape of the wind turbine tower.

In still other embodiments, the tower section may be part of a lattice tower or a space frame tower, and attachment of the gripping elements (see Fig. 5 and Fig. 6) may be provided directly at the lattices of the lattice or space frame tower.

Fig. 2 is a perspective view of a possible embodiment of a wind turbine separate add-on tower section 5 with provisions for securing gripping members (see Fig. 5 and Fig. 6) for an external equipment to the tower section. The separate add-on tower section 5 is provided with holes 6, said holes 6 provided along the circumference of the tower section. In the embodiment shown, holes 6 are provided two-and-two at six different locations along the circumference of the tower section 5.

Singular holes or more holes than two holes may be provided at different locations. Also, more or less locations than six locations may be selected for the one or more holes at each location. The number of holes and the number of locations along the circumference of the tower section may vary depending on the equipment to be supported by the gripping members (see fig. 5 and Fig. 6) and depending on the construction and the function of the gripping members.

The add-on tower section 5 is provided with a flange 7 along the inner circumference of the element. The flange 7 is provided with other holes 8 intended for bolts (not shown) extending through the other holes 8. The bolts are otherwise intended for securing a yawing mechanism (not shown) to the top of the wind turbine tower or as a tower segment in the passing from one tower segment to another tower segment, where the wall thickness of the tower often is increased for obtaining higher strength and/or for obtaining more tower wall thickness for the provision of holes for bolts mutually joining the tower sections.

Thus, the tower section 5 is inserted between a top flange (not shown) of the wind turbine tower and a mounting flange (not shown) of a yawing mechanism, or the tower section 5 is inserted between a top flange of one tower segment and a bottom flange of another tower segment placed above the one tower segment.

In the embodiment shown the tower section 5 is circular. Other shapes than circular, e.g. oval or polygonal, may be selected in stead depending on the construction and shape of the wind turbine tower.

In still other embodiments, the tower section may be part of a lattice tower or a space frame tower, and attachment of the gripping elements (see Fig. 5 and Fig. 6) may be provided directly on the lattices or the space frame of the tower. In the embodiments shown in Fig. 1 and Fig. 2, the holes 2 are provided two-and two at different locations around the tower segment. By providing the holes at different locations, the external equipment may be hoisted at different angular locations around the tower. It may be advantageous in case access to the tower is limited at the installation site of the wind turbine.

Fig. 3 is a longitudinal cross-section of part of a wind turbine tower 10. The wind turbine tower 10 is provided with platforms 11,12 at different levels inside the wind turbine tower. However, the platforms 11,12 are not a necessity for the provision of the present invention. On the other hand, the platforms 11,12 are man supports provided inside the wind turbine tower, and the platforms 11,12 are advantageous, when the gripping apparatus is operated.

The wind turbine tower is provided with holes 13,14 extending through the tower perpendicular to the circumference of the tower, i.e. extending radially in the embodiment shown. The holes 13,15 are preferably provided at a distance from the platforms 11,12 enabling a person to reach the holes when operating the gripping apparatus from the inside of the wind turbine. Thus, the holes 13,14 are preferably provided in a distance above the level of the platforms 13,14, respectively, of between 0.10 meters and 2.00 meters, preferably at a distance between 0.25 meters and 1.50 meters above the platforms, respectively.

Two peripheral holes 13 are provided at an upper part of the tower and one peripheral hole 14 is provided at a lower part of the tower. A further central hole 15 is provided at the upper part of the tower, between the two other holes 13 at the upper part of the tower. The central hole 15 is intended for a wire (not shown) extending through the central hole 15.

Either, the wire (not shown) is extending from a platform of the external equipment (see fig. 7) to the inside of the wind turbine tower, and within which the wire end is attached. Or, the wire is extending from the inside of the wind turbine to the platform, to which the wire end is attached.

The peripheral holes 13,14 in the wind turbine tower are provided for gripping members to be secured to the holes, e.g. gripping members as shown in Fig. 4 and Fig. 5, of the external equipment, said gripping members capable of engaging with the peripheral holes 13,14 in the wind turbine tower, when the equipment is in position.

In the embodiment shown in Fig. 3, the holes 13 are provided with an angular distance of 90 degrees. The lower hole 14 matches symmetrically with respect to the upper holes 13. Other similar holes (not shown) may be provided along the circumference of the tower so that a total of four holes 13 and four holes 14 are provided, each with a mutual angular distance of 90 degrees to a neighbouring hole. Thereby, the external equipment may be hoisted at four different angular locations around the tower. It may be advantageous in case access to the tower is limited at the installation site of the wind turbine.

Fig. 4 is a view of part of wind turbine nacelle 16 an upper section of a wind turbine tower 10. The wind turbine nacelle 16 is provided with two attachment points 17 in a bottom frame 19 of the nacelle 16 and the wind turbine tower 10 is provided with one hole 18 extending through the tower perpendicular to the circumference of the tower, i.e. extending radially in the embodiment shown.

The two attachment points 17 of the nacelle 16 are preferably holes 17 provided in the bottom frame 19 of the nacelle. In alternative embodiments, the holes 17 may be provided in a lower part of a nacelle frame of the nacelle 16. The one hole 18 in the tower is provided beneath the two holes 17 of the nacelle, symmetrically to the two holes 17 in the nacelle. The two holes 17 correspond to the holes 13 shown in Fig. 3, and the one hole 18 corresponds to the hole 14 shown in Fig. 3.

The holes 17,18 in the wind turbine nacelle frame and wind turbine tower are provided for gripping members, e.g. gripping members as shown in Fig. 5 and Fig. 6, of the external equipment to be secured to the wind turbine, each of said gripping members capable of engaging with the holes 17,18 in the wind turbine tower, when the equipment is in position.

In the embodiment shown in Fig. 4, the holes 17 are provided with an arbitrary angular distance. The lower hole 18 matches symmetrically with respect to the upper holes 17. Other similar holes (not shown) may be provided along the circumference of the tower so that a total of e.g. four lower holes 18, each with a mutual angular distance of 90 degrees to a neighbouring hole. Alternatively, another number of lower holes 18, e.g. one, two, three or more than four holes, and spaced apart with equal mutual angular distance may be provided.

The nacelle may be yawed so that the upper holes 17 match one of the lower holes 18. Thereby, the external equipment may be hoisted at different angular locations around the tower. It may be advantageous in case access to the tower is limited at the installation site of the wind turbine.

In the embodiments shown in Fig. 3 and Fig. 4, two upper holes and one lower hole is shown. In alternative embodiments, e.g. only one hole or more than two holes may be provided as upper holes, and more than one hole, e.g. two holes, may be provided as lower holes. The number of upper holes and lower holes may be selected depending on the construction and the weight of the external equipment. The number of upper holes and lower holes may be also or alternatively selected depending on the construction of the wind turbine itself.

Fig. 5 is a perspective view of a first embodiment of a gripping member 20 of the external equipment being in position of use, said gripping member being secured to a wind turbine tower 21 (shown partly). The gripping member 20 has a threaded part 22, i.e. like a bolt, extending through a hole 23 in the wind turbine tower 21.

The gripping member 20 is secured to the wind turbine tower 21 by a nut 24 tightening the gripping member 20 into abutment with an outer side wall 25 of the wind turbine tower 21. A washer plate 26 is provided between the nut 24 and an inner side wall 27 of the wind turbine tower 21. When the nut 24 is tightened, the washer plate 26 is forced towards the inner side wall 27 of the wind turbine tower 21. The gripping member 20 will thereby be radially and axially secured firmly to the outer side wall 25 of the wind turbine tower 20.

Furthermore, in the embodiment shown, elastomeric pads 28,29 are provided between the gripping member 15 and the outer side wall 26 of the wind turbine tower 21 and between the washer plate 26 and the inner side wall 27 of the wind turbine tower 21, respectively. The elastomeric pads 28,29 are intended for further securing the gripping member 20 axially.

Fig. 6 is a perspective view of a second embodiment of a gripping member 30 of the external equipment being in position of use, said gripping member being secured to a wind turbine tower 31 (shown partly). The gripping member has a threaded part 32 extending through a hole 33 in the wind turbine tower 31.

The gripping member 30 is secured to the wind turbine tower 31 by a nut 34 tightening the supporting part 30 into abutment with an outer side wall 35 of the wind turbine tower 31. A wedge-like washer ring 36 is provided around the threaded part 32, and when the nut 34 is tightened, the wedge-like washer ring 36 will be forced into the hole 33 in the wind turbine tower 31. The gripping member 30 will thereby be secured, both radially and circumferentially, firmly to the outer side wall 35 of wind turbine tower.

The gripping members shown in Fig. 5 and Fig. 6 are part of a support platform or other part of the equipment itself. Thus, when the equipment has been hoisted to a position of use, the one or more gripping members, e.g. as shown in Fig. 5 or Fig. 6, is secured to the wind turbine tower and will support the equipment to the wind turbine.

Fig. 7 A and Fig. 7B is a perspective view of an embodiment of a wire suspension 40 being part of either the nacelle frame 41 or, as shown, of a bottom frame 42 of the nacelle, said wire support 40 being situated inside the nacelle fuselage. As shown later in Fig. 10, a wire support constitutes a nacelle jib to be mounted to the nacelle just prior to hoisting the external equipment.

Different hereto, the wire support 40 shown in Fig. 7A and 7B is a fixed part of the nacelle frame 41 or bottom frame 42, the wire support 40 constituting a slot through which a pin 43 may be inserted for holding an eye 44 of a wire end 45. In the embodiment shown, the wire support 40 is part of the nacelle frame 41 or the bottom frame 42 at a location inside the nacelle fuselage. A hatch 46, preferably a hatch specifically provided for the wire end, is provided in the nacelle fuselage. Fig. 8 is a perspective view of an embodiment of a wire suspension 47 being part of the nacelle frame 41 or, as shown, the bottom frame 42 of the nacelle, said wire support 46 being situated outside the nacelle fuselage. As shown later in Fig. 10, a wire support constitutes a nacelle jib to be mounted to the nacelle just prior to hoisting the external equipment.

Different hereto, the wire support 45 shown in Fig. 8 is a fixed part of the nacelle frame 41 or the bottom frame 42, the wire support constituting a slot through which a pin 48 may be inserted for holding an eye 44 of the wire end 45. In the embodiment shown, the wire support is part of the nacelle frame 41 or the bottom frame 42 at a location outside the nacelle fuselage. Thus, no hatch for the wire end is needed in the nacelle fuselage, the wire support 46 is readily accessible from beneath the nacelle, without the need for access through the nacelle fuselage.

Fig. 9 shows a truck 50 carrying the gripping apparatus (see Fig. 1A-4D and Fig. 8) together with equipment for handling the gripping apparatus. The equipment for handling the gripping apparatus comprises a wire support (see Fig. 6) a nacelle jip (see Fig. 7) and a wire winch of the truck itself (see Fig. 9).

Fig. 10 shows a wire suspension 51 with four wire suspension elements 52. In the embodiment shown, the wire suspending elements are pulleys passing a cable, thus increasing the power transmission ratio of the hydraulic or electrical motors on the gripping apparatus when the gripping apparatus is to be hoisted from the truck. In an alternative embodiment, the wire suspending elements may be eyes for attaching one end of a cable to the eyes, possibly by means of shackles.

In the embodiment shown, the wire suspension 51 has a frame 53 supporting the four pulleys 52 in each corner of the frame. In alternative embodiments, the wire suspension may have more or fewer than four pulleys and the pulleys may be positioned in different locations of the frame than in the corners of the frame. The number of pulleys and the position of the pulleys in the frame of the pulley may depend on the design of the wind turbine, especially the design of the nacelle, which the wire suspension is to cooperate with, i.e. how much space is available underneath the nacelle. The wire suspension has a holdfast 54 facing the tower. The holdfast 54 is intended for abutting the tower when the wire suspension 51 is in position underneath the nacelle (see Fig. 7). Furthermore, the wire suspension 51 is provided with a linkage 55 for linking the wire suspension 51 to the nacelle once the wire suspension 51 has been hoisted to the position underneath the nacelle. The linkage 55 may have a certain extension adapted for the wind turbine in question. By providing a linkage 55 adapted for the wind turbine in question, it is possible to adapt the linkage 55 to a nacelle of a certain type and kind of wind turbine in question.

The wire suspension 51 is hoisted towards the top of the tower by a wire 56 extending from a nacelle jib (see Fig. 7) mounted to a supporting structure of the nacelle. During hoisting, the wire suspension 51 is preferably laterally restrained, thus prevented the wire suspension from clashing into the tower, By being laterally restrained, the wire suspension is furthermore prevented from being dragged upwards along the tower, possibly damaging any surface coating of the tower. Wires 57 being suspended from the wire suspension 51 are allowed to run out from the gripping apparatus, which is still situated on the truck (see Fig. 5). But the wires 57 are kept taut during hoisting of the wire suspension 51 so that the wire suspension 51 is maintained in distance from the tower, until the wire suspension 51 is in position underneath the nacelle (see Fig. 7).

Fig. 11 shows the wire suspension 51 after having been hoisted to the position underneath the nacelle. The wire suspension 51 is hoisted to the nacelle by a single wire 56, said single wire 56 extending from a nacelle jib 58. Preliminary to the wire suspension 51 being hoisted from the truck 50 to the position underneath the nacelle, the nacelle jib 58 is mounted to a supporting structure 59 of the nacelle.

Preliminary to the wire suspension 51, and subsequently the gripping apparatus, being lifted from the truck 50, the nacelle jip 58 is hoisted to the nacelle, either from the outside of the nacelle or inside the tower by an onboard hoisting equipment of the nacelle. In the embodiment shown, the nacelle is provided with a hatch opening 60 through which the nacelle jib 58 is extending after having been mounted to the supporting structure 59 of the nacelle. In the embodiment shown, the supporting structure 59 is a part of the frame structure of the nacelle. Subsequent to mounting of the nacelle jib 58 to the supporting structure 58 of the nacelle, the wire suspension 51 may be lifted from the truck 50, while being suspended in the single wire 56 extending from the nacelle jib 58.

The nacelle jib 58 may be mounted to any supporting structure of the nacelle as long as the supporting structure of the nacelle is capable of withstanding the load of the gripping apparatus with equipment and with any element of the nacelle, e.g. the gear box or the generator, which may be intended for being supported by the gripping apparatus during maintenance or replacement. Alternatively, part of the top of the tower, possibly a mounting flange on top of the tower, or any other structural part of the upper part of the wind turbine, said part being capable of withstanding the loads, may be adapted for supporting the nacelle jib.

Hoisting of the gripping apparatus itself takes place by means of wires extending from the gripping apparatus upwards to the wire suspension 51 mounted underneath the nacelle and back to the hydraulic or electrical winches (not shown) mounted on the gripping apparatus. In the embodiment shown, four cables 57 are each extending from the gripping apparatus and around each a pulley 52 of the wire suspension 51 for thereby suspending the gripping apparatus in eight cable extensions in total. Due to this power distribution, the power capacity needed is limited of the winches of the gripping apparatus for hoisting the apparatus.

In alternative embodiments, more or fewer wires may be used, even as few as one wire may be used, said at last one wire possibly being attached by a hook or similar fastening element to the nacelle jib (see Fig. 8). Thereby, the wire suspension may be omitted, and the gripping apparatus will be suspended directly from the nacelle jib. The need for more wires than one or fewer wires than four, and the need for a wire suspension, possibly with pulleys for power distribution, depends on the weight of the gripping apparatus itself, depends on the elements being lifted to or from the nacelle and which are to be supported by the gripping apparatus, depends on the dimensioning of the wire or wires and depends on the possible safety factor used for dimensioning the wire or wires. Fig. 12 shows a wire winch 61 of the truck 50. The truck 50 is preferably the truck also having transported the gripping apparatus and the equipment for handling the gripping apparatus to the site of the wind turbine. The wire winch 61 is hydraulically or electrically operated, or the wire winch 61 may be operated mechanically by mechanical power transmission from an engine of the truck 50. Alternatively to the wire winch 61 being an integrate wire winch of a truck, as shown, the wire winch may be separate from the truck, but the wire winch may possibly still be operated hydraulically, electrically or mechanically by power from the engine of the truck.

The wire winch 61 is used for laterally restraining the gripping apparatus and thus preventing the gripping apparatus from clashing into the tower. By being laterally restrained the gripping apparatus is furthermore prevented from being dragged upwards along the tower, possibly damaging a surface coating of the tower. A wire 62 of the wire winch 61 is allowed to run out from the wire winch, but the wire is kept taut during hoisting of the gripping apparatus, so that the gripping apparatus is maintained in distance from the tower until the gripping apparatus is in a desired position along the tower.

Only when the gripping apparatus is in the desired location along the tower is the wire 62 from the wire winch 61 allowed to run so far out from the wire winch 61 that the wire loosen, thereby allowing the gripping apparatus to abut the tower and subsequently grip around the tower. According to this preferred method, the truck 50 constitutes a ground object being non-displaced and the taut wire 62 of the wire winch 61 ensuring lateral restraint of the gripping apparatus.

Alternatively to allowing the wire 62 to run out from the wire winch 61, and where the wire 62 is kept taut during hoisting of the gripping apparatus, the wire 62 may be kept taut, during hoisting of the gripping apparatus, by means of the truck 50 driving towards the tower at a speed ensuring possibility of constant hoisting of the gripping apparatus upwards, but at the same time ensuring maintaining the gripping apparatus at a distance from the tower, until the gripping apparatus is in the desired location along the tower. Only when the gripping apparatus is in the desired location along the tower is the truck 50 driven so far towards the tower that the wire 62 from the truck 50 is allowed to loosen for the gripping apparatus to abut the tower and subsequently grip around the tower. According to this alternative method, the truck 50 constitutes a ground object being displaced and ensuring lateral restraint of the gripping apparatus. Also according to this alternative embodiment, a wire winch 61 may be omitted. A fixed length wire 62 may be used.

However, preferably, the wire winch 61 is used for laterally restraining the gripping apparatus and thus preventing the gripping apparatus from clashing into the tower, only before the gripping apparatus is hoisted and/or only until the gripping apparatus is hoisted to a level above the entrance door to the wind turbine tower. By being laterally freed the gripping apparatus will be dragged upwards along the tower. Rollers may be provided as shown, preventing damaging the surface coating of the tower. Thus, the wire 62 of the wire winch 61 is allowed to run out from the wire winch, also during hoisting of the gripping apparatus, so that the gripping apparatus is abutting the wind turbine tower until the gripping apparatus is in a desired position along the tower.

In the embodiment shown, pulleys 63 are provided for providing power distribution, thereby reducing the need for power capacity of the wire winch 61. The pulleys are attached to a frame 64 of the wire winch 61 and to an intermediate pulley suspension 65, Furthermore, between the intermediate pulley suspension 65 and the gripping apparatus (not shown), elastomeric elements 66, e.g. rubber strings as shown, is provided for absorbing amplitude and/or frequency of possible oscillations of the gripping apparatus when being hoisted towards a position along the tower.

The forces to be taken up by the wire 62 of the wire winch 61 may however be limited. Therefore, in the alternative, the wire may be substituted by a rope of an elastomeric material such as polyethylene or other material being more or less elastomeric and at the same time having a relatively high tensile strength compared to other elastomeric materials. A rope of an elastomeric material and having a relatively high tensile strength will render the elastomeric string shown in Fig. 9 unnecessary and will possibly increase the safety towards any hazards which may occur due to possible risk of rupture of the elastomeric string.

Even in the alternative, the wire of the wire winch may have enough elasticity to take up a sufficient amplitude and/or frequency of oscillations during hoisting of the gripping apparatus. If that is the case, the elastomeric strips may be omitted.

In the embodiment shown, the gripping apparatus is provided with a crane extending upwards from the gripping apparatus. The crane is capable of accessing a top of the wind turbine nacelle, when the gripping apparatus is in a position of use on a wind turbine tower. Access to the top of the nacelle is established by the gripping apparatus being in position of use set aside in relation to the nacelle, when viewed perpendicular to a horizontal plane, and the crane being rigid by having no toggle-joints. Thus, although the gripping equipment is positioned beneath the nacelle, the crane is still capable of accessing the top of the nacelle.

In an alternative embodiment, the gripping apparatus is provided with a crane also extending upwards from the gripping apparatus. The crane is also capable of accessing a top of the wind turbine nacelle, when the gripping apparatus is in the position of use on a wind turbine tower: However, access to the top of the nacelle being established by the gripping apparatus being in position of use below the nacelle, when viewed perpendicular to a horizontal plane, and the crane being flexible by having at least one toggle-joint. The capability of the crane of accessing the top of the nacelle is enhanced when having at least one toggle joint.

Although the present invention has been described in connection with a specified embodiment, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is to be interpreted in the light of the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

1. A method of handling and/or servicing components of a wind turbine, said method comprising the steps of: - positioning an external equipment in vicinity of a lower part of a wind turbine tower previously having been installed at a wind turbine site,

- connecting the external equipment to an upper part of the wind turbine with at least one cable being suspended from the upper part,

- raising the external equipment to a position of use by means of the at least one cable by use of cable winding or hoisting equipment, and

- attaching each of said at least two gripping members to at least one of the following parts of the wind turbine: an attachment point of the nacelle frame, an attachment point of a bottom frame of the nacelle, or an attachment point at the outer circumference of the wind turbine tower,

- transferring at least part of a vertical load and part of the torque loads provided by the external equipment to the wind turbine via said at least two gripping members forming an attachment of the external equipment to the wind turbine.

2. A method according to claim 1, said method comprising

- holding the external equipment onto a side wall of the wind turbine tower by use of at least three gripping members, where at least two gripping members are positioned above at least one other gripping member.

3. A method according to claim 1 or claim 2, where said at least two gripping members constitute a fixed member of the external equipment, and

- when the external equipment is in a position of use, extending and securing said at least two gripping members through and to an attachment point, said attachment point being a hole in the outer circumference of the wind turbine.

4. A method according to claim 1 or claim 2, where said at least two gripping members constitute a fixed member of the external equipment, and - when the external equipment is in a position of use, extending and securing said at least two gripping members to an attachment point in the bottom frame of the wind turbine, and inside the nacelle fuselage.

5. A method according to claim 1 or claim 2, where said at least two gripping members constitute a fixed member of the external equipment, and

- when the external equipment is in a position of use, extending and securing said at least gripping members to an attachment point in the bottom frame of the wind turbine, and outside the nacelle fuselage.

6. A method according to any of claims 1-5,

- when the external equipment is in the position of use, extending said at least two gripping members having a threaded part entirely through an attachment point, said attachment point being a the hole in the outer circumference of the wind turbine tower, or in the bottom frame, or in the nacelle frame, and - securing said at least two gripping members to the wind turbine by at least one nut, said at least one nut being brought in engagement with the threaded part from the inside of the wind turbine tower or the inside of the nacelle fuselage.

7. A method according to any of claim 1-5, - when the external equipment is in the position of use, extending said at least two gripping members having an expanding part entirely through an attachment point, said attachment point being a hole in the outer circumference of the wind turbine tower, or in the bottom frame, or in the nacelle frame, and

- securing said at least two gripping members to the wind turbine tower, or to the bottom frame, or to the nacelle frame, by an expansion taking place inside of the wind turbine when the expansion part has been extended through the hole,

- said expansion resulting in the expansion part obtaining a larger circumference than the a circumference of the hole in the wind turbine tower or the hole of the nacelle frame.

8. A method according to any of claims 1-5,

- when the external equipment is in the position of use, extending said at least two gripping members having a slotted part entirely through an attachment point, said attachment point being a hole in the outer circumference of the wind turbine tower, or in the bottom frame, or in the nacelle frame, and - securing said at least two gripping members to the wind turbine tower, or to the bottom frame, or to the nacelle frame, by a traverse element being brought in engagement with the slotted part from the inside of the wind turbine tower.

9. A method according to any of claims 1-5,

- when the external equipment is in the position of use, extending said at least two gripping members having a pin through an attachment point, said attachment point being a hole in the outer circumference of the wind turbine tower, or in the bottom frame, or in the nacelle frame, - limiting said pin from disengaging from the hole, when the external equipment is to be maintained in a position of use, and

- retracting said pin from extension through the hole in the outer circumference of the wind turbine tower, or in the bottom frame, or in the nacelle frame, by

- allowing the pin to disengage from the hole, when the external equipment is to be released from the position of use.

10. A gripping apparatus for mounting equipment to a wind turbine tower, said gripping apparatus comprising

- at least two gripping members capable of being attached to at least one of the following parts of the wind turbine: an attachment point of the nacelle frame, an attachment point of a bottom frame of the nacelle, or an attachment point at the outer circumference of the wind turbine tower, and said at least two gripping members capable of supporting a external equipment,

- said at least two gripping members having a part constituting an attachment for securing the at least two gripping members to the wind turbine, when the external equipment is in a position of use, and

- said at least two gripping members capable of being attached to the wind turbine for forming an attachment of the external equipment to the wind turbine tower, when the equipment is in a position of use.

11. A griping apparatus according to claim 10, said gripping apparatus comprising at least three gripping members, where at least two gripping members are positioned above at least one other gripping member.

12. A gripping apparatus according to claim 10 or claim 11, where each of said at least two gripping members have a threaded part and a corresponding nut, and where each of said at least two gripping members are capable of being secured to the wind turbine tower, or to the nacelle frame or to the bottom frame by the nut being brought in engagement with the threaded part.

13. A gripping apparatus according to claim 10 or claim 11, where each of said at least two gripping members have an expanding part, and where each of said at least two gripping members are capable of being secured to the wind turbine tower, or to the nacelle frame or to the bottom frame by an expansion of the expanding part when inserted through a hole in the wind turbine tower.

14. A gripping apparatus according to claim 10 or claim 11, where each of said at least two gripping members have a slotted part, and where each of said at least two gripping members are capable of being secured to the wind turbine tower, or to the nacelle frame or to the bottom frame by a traverse element being brought in engagement with the slotted part.

15. A wind turbine tower comprising - at least two attachment points capable of attaching a gripping apparatus to the wind turbine tower,

- said at least two attachment points being positioned on or being provided in the outer side wall of the wind turbine tower, and

- said at least two attachment points being arranged with a distance, circumferentially, along the circumference of the wind turbine tower.

16. A wind turbine tower according to claim 15, where the at least two attachment points are holes extending through the side wall of the wind turbine tower.

17. A wind turbine tower according to claim 15 or claim 16, where at least three attachment are provided, where at least two of said at least three attachment points are positioned above at least one other of said at least three attachment points.

18. A wind turbine tower according to claim any of claims 15-17, said at least two holes in the wind turbine tower being provided in a distance between 0.10 and 2.00 meters, preferably in a distance between 0.25 and 1.50 meters above a man-support, preferably above a working platform, inside the wind turbine tower.

19. A wind turbine tower according to any of claims 16-18, where said at least two holes are provided with an angular distance being a multiple of 15 degrees, and where the number of holes are 360 degrees divided by the multiple of 15 degrees.

20. A wind turbine with a gripping apparatus, said gripping apparatus comprising

- at least two gripping members of an external equipment, said at least two gripping members capable of being attached to at least one of the following parts of the wind turbine: an attachment point of the nacelle frame, an attachment point of a bottom frame of the nacelle, or an attachment point at the outer circumference of the wind turbine tower, and said at least two gripping members capable of supporting the external equipment,

- a part of each of said at least two gripping members constituting an attachment for attaching the at least two gripping members to the nacelle frame, or to an attachment point of a bottom frame of the nacelle, or to an attachment point at the outer circumference of the wind turbine tower, when the external equipment is in a position of use, and

- said at least two gripping members also capable of being secured to the nacelle frame, or to the bottom frame of the nacelle, or to the outer circumference of the wind turbine tower for forming an attachment and a securing of the external equipment to the wind turbine, when the equipment is in a position of use.

21. A wind turbine according to claim 21, where the attachment point is at least two holes extending through the side wall of the wind turbine tower.

22. A wind turbine tower according to claim 21, where the attachment point is at least two holes extending into a nacelle frame of the wind turbine nacelle.

23. A wind turbine tower according to claim 21, where the attachment point is at least two holes extending into a bottom frame of the wind turbine nacelle.