EP4792022A1 - A bolt and spacer assembly - Google Patents

Abstract

The invention provides a bolt and spacer assembly - comprising a bolt (2) comprising a head (201) and an elongated bolt body (202), the bolt body being terminated at a penetration end (203) located at a distance from the head, - which bolt body (202) is adapted to penetrate a first hole (1411) in a first wind turbine tower section (141), and to penetrate a second hole in a second wind turbine tower section (142) for a bolted connection of the wind turbine tower sections, - wherein the bolt and spacer assembly further comprises a spacer (3) adapted to assume, when the penetration end is inserted into the first hole and the head is above the penetration end, a spacing position in which the spacer by contact with the head and the first wind turbine tower section keeps the head and the first wind turbine tower section apart, - wherein the spacer presents, in the spacing position and as seen along a longitudinal direction of the bolt body, an open profile such that an opening is formed between ends (301E, 302E) of the profile so that the spacer (3) partly surrounds the bolt body (202). - The spacer is adapted to be turned from the spacing position around a turning axis (TA) which is transverse to the longitudinal direction of the bolt body so that at least a part of the bolt body is moved out through the opening formed between the ends (301E, 302E) of the spacer profile, so as to allow the bolt body to further enter the first hole as the bolt moves under the influence of gravity acting on the bolt, and - the spacer is adapted to contact the bolt (2) so as to dampen the move of the bolt as the bolt moves upon said turning of the spacer.

Description

A BOLT AND SPACER ASSEMBLY

TECHNICAL FIELD

The present invention relates to a bolt and spacer assembly, preferably for a wind turbine tower assembly procedure. The invention also relates to combination of a bolt and spacer assembly, a first wind turbine tower section, and a second wind turbine tower section. The invention also relates to spacer, and a method for connecting a first wind turbine tower section to a second wind turbine tower section.

BACKGROUND

A horizontal axis wind turbine is known to have an electric generator in a nacelle on top of a tower, where a rotor, with one or more blades, with a substantially horizontal axis, is mounted to the nacelle and arranged to drive the generator.

The tower of a horizontal axis wind turbine often comprises two or more tower sections, e.g. in steel. The tower sections may be cylindrical or have the shape of a truncated cone. The tower sections may be stacked on top of each other and joined at horizontal interfaces. At such an interface, an upper and a lower tower section may be joined by a series of bolts extending through adjacent flanges extending inwardly from the tower walls and along the circumference of the interface.

When erecting wind turbine towers, usually a crane is used for moving a tower section on top of another one. Besides retaining safety of staff involved with the tower erection, and avoiding damage to wind turbine parts or tools used for the erection, there is a great interest in keeping crane time as low as possible. There is therefore a desire to provide a wind turbine tower erection solution which is safe and effective, and which minimises the risk of damage.

SUMMARY OF THE INVENTION

The object of the invention is to provide a wind turbine tower erection solution which is safe and effective, and which minimises the risk of damage to wind turbine parts or tools used for the erection. This object of the invention is reached with a method according to claim 1. Thus, the invention provides a bolt and spacer assembly comprising a bolt comprising a head and an elongated bolt body, the bolt body being terminated at a penetration end located at a distance from the head. The bolt body is adapted to penetrate a first hole in a first wind turbine tower section, and to penetrate a second hole in a second wind turbine tower section for a bolted connection of the wind turbine tower sections. The bolt and spacer assembly further comprises a spacer adapted to assume, when the penetration end is inserted into the first hole and the head is above the penetration end, a spacing position in which the spacer by contact with the head and the first wind turbine tower section keeps the head and the first wind turbine tower section apart. The spacer presents, in the spacing position and as seen along a longitudinal direction of the bolt body, an open profile such that an opening is formed between ends of the profile so that the spacer partly surrounds the bolt body.

The spacer is adapted to be turned from the spacing position around a turning axis which is transverse to the longitudinal direction of the bolt body so that at least a part of the bolt body is moved out through the opening formed between the ends of the spacer profile, so as to allow the bolt body to further enter the first hole as the bolt moves under the influence of gravity acting on the bolt. The spacer is further adapted to contact the bolt so as to dampen the move of the bolt as the bolt moves upon said turning of the spacer.

The bolt head may, or may not, comprise a washer. For, example, the bolt may comprise a studbolt with a head formed by a nut and a washer, or the bolt may be a headed bolt. The bolt body may be at least partly threaded. Preferably, the first and second holes are cylindrical. Preferably, the bolt body is adapted to first the first hole, and subsequently penetrate the second hole.

The spacer may be made of any suitable material, e.g. plastic, cardboard, metal, rubber, or a combination of two or more of these materials. The spacer preferably presents a slot extending in the spacing position along the longitudinal direction of the bolt body. Preferably, in the spacing position of the spacer, the spacer partly tightly surrounds the bolt body along a transverse angular interval which is larger than 180 degrees. The distance between the ends of the profile of the spacer may be smaller than the diameter of the bolt body. For the spacing position, preferably the spacer extends transversely to the bolt body, to a distance from a centreline of the bolt body that is larger than the radius of the first hole. Preferably the bolt head has an extension transversely from the centreline of the bolt body which is, in the spacing position of the spacer, larger than a minimum distance from the centreline of the bolt body to an internal delimitation of the spacer.

Preferably, in the spacing position a spacing direction of the spacer is parallel with the longitudinal direction of the bolt body. The spacer preferably has a cavity and openings at ends in the spacing direction. Said partial surrounding of the bolt body in the spacing position could be provided by clasping means of the spacer.

For the turning from the spacing position, the spacer may comprise a turning device adapted to be subjected to a force or a moment for the turning of the spacer. Thereby, the spacer may be pulled transversely to create a lateral force, or the spacer may be subjected to a bending moment. Upon said turning the spacer, the spacing direction of the spacer may be moved into a non-zero angle to the bolt body longitudinal direction. Upon said turning the spacer, a part of the clasping means may be removed from the bolt body.

In a tower erection process, the second tower section may be installed, e.g. on a foundation or on a further tower section. At an upper end, the second tower section may present a plurality of the second holes, distributed in a circumferential direction of a circular interface of the second tower section. Further, the first tower section may be upended, and lifted, e.g. with a crane, at positioned on top of the second tower section. At a lower end, the first tower section may present a plurality of the first holes, distributed in a circumferential direction of a circular interface of the first tower section, and provided in a mounting flange of the first tower section. Upon positioning the first tower section in this manner, the first holes are aligned with the second holes.

The invention allows for a plurality of bolt and spacer assemblies according to an embodiment of the invention to be used such that the penetration end of each bolt is inserted into a respective of the first holes, and the spacer of each assembly is placed in the spacing position so as to keep the respective bolt head and the mounting flange of the first tower section apart. Each spacer can be used when placing the respective bolt temporarily in the respective first hole, which may be a flange hole, in the upended first tower section. Thereby, the bolts can be carried together with the first tower section when lifted onto the second tower section. Thereby, interference of the bolts with a position guiding system for the tower section installation can be avoided.

Since the spacer presents an open profile so that the spacer partly surrounds the bolt body, the spacer can be removed laterally. Thereby, there steps of lifting the bolts, which may be large, e.g. with a bolt body diameter of 40 mm, and therefore heavy, to remove the spacers, can be omitted. Thereby, in view of the large number of bolts in the tower of a modem multi megawatt wind turbine, the tower erection time can be significantly reduced.

Further, when the spacer is turned from the spacing position, and the bolt falls, the bolt may be guided by the first hole. Since the spacer is adapted to contact the bolt so as to dampen the fall of the bolt as the bolt, the bolt can be lowered safely into the hole without significant impact against the flange upper surface. Thereby, damage of the flange surface, e.g. a surface treatment thereof, can be avoided.

Furthermore, the bolts can potentially be prepared before transport to the tower erection site, with the spacers already fitted on them, whereby further installation time is saved. In addition, the spacer can potentially be re-used.

Thereby, a tower erection solution is provided which is safe and effective, and which minimises the risk of damage to wind turbine parts or tools used for the erection.

For the spacer to be turned from the spacing position, a turning device may be provided and adapted to be subjected to a force or a moment for the turning of the spacer. In some embodiments, the turning device is located closer to a second end than to a first end of the spacer, wherein the turning device, e.g., in the form of a string, is adapted to be engaged with force applying means, e.g. an operator hand or a tool, and to be subjected to a lateral force to move the second end laterally.

In some embodiments, said adaption of the spacer to contact the bolt comprises the spacer being adapted to contact the bolt head so as to dampen the move of the bolt. Where the spacer may extends, in the spacing position and in the longitudinal direction of the bolt body, between a first end and a second end of the spacer, said adaption of the spacer to contact the bolt may comprise the spacer being adapted to allow the first end of the spacer to be pinched between the bolt head and the first tower section. Thereby, the spacer may serve as a “cushion” between the bolt head and the first tower section flange, avoiding a potentially damaging impact between the head and the flange.

In some embodiments, where the spacer extends, in the spacing position and in the longitudinal direction of the bolt body, between a first end and a second end of the spacer, the spacer is adapted so that during said turning of the spacer the second end moves further than the first end, wherein the first end of the spacer is formed by two protruding end retaining elements distributed, in the spacing position of the spacer, in parallel with the turning axis and on opposite transverse sides of the bolt body. The end retaining elements may form two abutment surfaces adapted to abut the head of the bolt or the first tower section, in the spacing position of the spacer. The abutment surfaces may be curved to follow bolt body along respective parts of its circumference. The end retaining elements may be separated by a cutout in the first end of the spacer. The first end may be symmetric with the end retaining elements on opposite sides of the symmetry plane.

Thereby, turning of the spacer may be done by moving, e.g. by pulling, the second end laterally, e.g. by a turning device as exemplified above, and allow the end retaining elements at the first end to remain on either side of the bolt body. Thereby, the end retaining elements can be allowed to be pinched between the bolt head and the first tower section to dampen the fall of the bolt.

In some embodiment, the spacer comprises two clips which, in the spacing position of the spacer, partly surround the bolt body along a transverse angular interval which is larger than 180 degrees, and which, in the spacing position of the spacer, are separated in the longitudinal direction of the bolt body by an intermediate part which is not adapted to partly surround the bolt body along a transverse angular interval which is larger than 180 degrees.

Thereby, it may be secured that, when the spacer is turned, one of the clips could remain engaged with the bolt body. This may facilitate the turning of spacer. However, in some embodiments, the spacer may have only a single clasp. As suggested, the opening formed between the ends of the spacer profile may form a slot extending, in the spacing position of the spacer, along the longitudinal axis of bolt body. Thereby, in some embodiments, the spacer comprises two dampening edges extending, in the spacing position of the spacer, at least partly in the longitudinal direction of bolt body, on opposite sides of the slot. Thereby, the spacer being adapted to contact the bolt, as the bolt moves under the influence of gravity upon said turning of the spacer, may comprise the dampening edges being adapted to contact the bolt on opposite sides of the bolt body, so that, as the spacer is turned, points of contact between the dampening edges and the bolt move along the dampening edges. The dampening edges may be located on the same side of a plane, formed by a bolt centre axis and an imaginary axis extending through and transversely to the bolt centre axis, as the ends of the spacer profile.

The dampening edges may be provided on respective flanges of the spacer. The dampening edges may be curved and convex as seen along the turning axis of the spacer. The dampening edges being adapted to contact the bolt may comprise the dampening edges being adapted to contact the bolt head.

In embodiments with the dampening edges, the spacer may be turned manually with a turning device in the form of a lever which is fixed to the spacer and protrudes therefrom. As the spacer is turned, a lower edge of the head of the bolt may glide along the dampening edges. Thereby, the rotational speed of the spacer turning can decide the speed at which the bolt moves downwards.

In some embodiments, said adaption of the spacer to contact the bolt head so as to dampen the move of the bolt comprises allowing the move of the bolt to be dampened by friction between the spacer and threads of the bolt body. Such embodiments may comprise spacers with end retaining elements, as exemplified above, whereby the end retaining elements are scraped by the bolt threads as the bolt moves downwards.

The object is also reached with a combination of a bolt and spacer assembly according to any embodiment of the invention, a first wind turbine tower section, and a second wind turbine tower section, wherein the bolt body of the bolt is adapted to penetrate a first hole in the first wind turbine tower section, and to penetrate a second hole in the second wind turbine tower section for a bolted connection of the wind turbine tower sections.

The object is also reached with a spacer for a bolt and spacer assembly according to any embodiment of the invention.

The object is also reached with a method for connecting a first tower section for a wind turbine to a second tower section for the wind turbine. For example, a flange of the first tower section may be connected with a flange of the second tower section.

The method comprises positioning a spacer on an elongated bolt body of a bolt wherein the spacer presents, as seen along a longitudinal direction of the bolt body, an open profile such that an opening is formed between ends of the profile so that the spacer partly surrounds the bolt body. The method further comprises inserting a penetration end of the bolt body into a first hole in the first tower section, so that the head of the bolt is above the penetration end. The spacer, positioned on the bolt body of the bolt the penetration end of which is inserted into the first hole, assumes a spacing position in which the spacer by contact with the bolt head and the first wind turbine tower section keeps the head and the first wind turbine tower section apart.

The method further comprises turning the spacer from the spacing position around a turning axis which is transverse to the longitudinal direction of the bolt body so that at least a part of the bolt body is moved out through the opening formed between the ends of the spacer profile, so as to allow the bolt body to further enter the first hole as the bolt moves under the influence of gravity acting on the bolt. The method further comprises allowing, as the bolt moves upon said turning of the spacer, the spacer to contact the bolt so as to dampen the move of the bolt, and subsequently securing the bolt for a bolted connection of the wind turbine tower sections wherein the bolt body penetrates the first hole and a second hole in the second wind turbine tower section.

Preferably, the spacer is allowed to contact the bolt head so as to dampen the move of the bolt. The method may comprise positioning the spacer on a first part of the bolt body, and positioning a second part of the bolt body in the first hole in the first tower section. It should be noted that positioning the spacer and inserting the penetration end in the first hole could be in any mutual order. Preferably, before the step of turning the spacer, the first tower section is positioned on the second tower section so that the first hole is aligned with a second hole in the second tower section.

In some embodiments of the method, wherein the spacer extends, in the spacing position and in the longitudinal direction of the bolt body, between a first end and a second end of the spacer, wherein said contact of the spacer so as to dampen the move of the bolt comprises allowing the first end of the spacer to be pinched between the bolt head and the first tower section. For this, the first end of the spacer could be, as suggested above, formed by two protruding end retaining elements distributed, in the spacing position of the spacer, in parallel with the turning axis and on opposite transverse sides of the bolt body. Thereby, the end retaining elements can be allowed to be pinched between the bolt head and the first tower section to dampen the fall of the bolt. However, in some embodiments, the first end could be provided without such end retaining elements. Thereby, the first end may still be allowed to be pinched between the bolt head and the first tower section to dampen the fall of the bolt.

In some embodiments of the method, wherein the opening formed between the ends of the spacer profile forms a slot extending, in the spacing position of the spacer, along the longitudinal axis of bolt body, the spacer comprises two dampening edges extending, in the spacing position of the spacer, at least partly in the longitudinal direction of bolt body, on opposite sides of the slot. Thereby, said contact of the spacer so as to dampen the move of the bolt may comprise the dampening edges contacting the bolt on opposite sides of the bolt body, so that, as the spacer is turned, points of contact between the dampening edges and the bolt move along the dampening edges.

BRIEF DESCRIPTION OF THE DRAWINGS

Below examples of the invention will be described in detail with reference to the drawings, in which: fig. 1 is a view of a wind turbine, - fig. 2 is a perspective sectioned view of a part of a tower of the wind turbine, during assembly of the tower,

- fig 3 - fig. 6 are orthogonal side views of a bolt and spacer assembly used in the tower assembly,

- fig. 7 is a view from below of the bolt and spacer assembly in fig 3 - fig. 6,

- fig. 8 - fig. 10 are perspective views as the one in fig. 2, showing steps in an embodiment of a method according to the invention,

- fig. 11 - fig. 12 show perspective views of a spacer according to an alternative embodiment of the invention,

- fig. 13 shows a view of the spacer in fig. 11 - fig. 12, along a longitudinal axis of a bolt body which the spacer is intended to engage,

- fig. 14 - fig. 16 are perspective sectioned views of a part of a wind turbine tower, showing steps in an alternative embodiment of the method according to the invention, using the spacer in fig. 11 - fig. 13,

- fig. 17 is a flow diagram depicting steps of an embodiment of a method according to the invention,

- fig. 18 - fig. 19 show side views of a spacer according to a further alternative embodiment of the invention,

- fig. 20 shows a top view of the spacer in fig. fig. 18 - fig. 19, and

- fig. 21 and fig. 22 show bolt and spacer assemblies according to respective further alternatives of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Fig. 1 shows a horizontal axis wind turbine 1. In this example, the wind turbine is an onshore wind turbine. However, the invention is equally applicable to an offshore wind turbine.

The wind turbine 1 comprises a tower 14 supporting a nacelle 15. A rotor 16 is mounted to the nacelle. The tower is supported by a foundation 17. The rotor 16 comprises a plurality of wind turbine blades 11, 12, 13 that extend radially from a central hub 18. In this example, the rotor 16 comprises three blades 11, 12, 13. The hub 18 is mounted to the nacelle 15.

The tower 14 comprises tower sections stacked on top of each other, and joined using bolt and spacer assemblies described closer below. For this presentation, one of the tower sections is referred to as a first tower section 141, and another of the tower section, located below the first tower section 141 and adjacent to the first tower section 141, is referred to as a second tower section 142.

Reference is made also to fig. 2 - fig. 7. For connecting the first and second tower sections 141, 142 a plurality of bolt and spacer assemblies are used. Each bolt and spacer assembly comprises a bolt 2 comprising a head 201 and an elongated bolt body 202, the bolt body being terminated at a penetration end 203 located at a distance from the head. The bolt body 202 is adapted to penetrate a first hole 1411 in a flange 1412 of the first tower section 141, and to penetrate a second hole (not shown) in a flange 1422 of the second tower section 142 for a bolted connection of the wind turbine tower sections.

The bolt and spacer assembly further comprises a spacer 3. The spacer is adapted to assume, when the penetration end 203 is inserted into the first hole 1411 (fig. 2) and the head 201 is above the penetration end, a spacing position, shown in fig. 2. In the spacing position, the spacer 3 keeps the head and the flange 1412 of the first tower section 141 apart.

As can be seen e.g. in fig. 4 and fig. 7, the spacer presents, in the spacing position and as seen along a longitudinal direction of the bolt body 202, an open profile such that an opening is formed between ends 301E, 302E of the profile. Thereby, the spacer 3 partly surrounds the bolt body 202.

As indicated in fig. 4, the spacer comprises two clips 301, 302 which, in the spacing position of the spacer, partly surround the bolt body 202. As indicated in fig. 7, the clips surround the bolt body along a transverse angular interval Al which is larger than 180 degrees. As indicated in fig. 4, the clips 301, 302 are separated in the longitudinal direction of the bolt body 202 by an intermediate part 303. The intermediate part 303 is adapted to partly surround the bolt body 202 along a transverse angular interval which is less than 180 degrees.

As indicated in fig. 3, the spacer 3 presents a first end 31 IE, 312E and a second end 3E. In the spacing position, the bolt head 202 is in contact with the first end 31 IE, 312E, and the second end 3E is in contact with the tower section flange 1412. The first end 31 IE, 312E of the spacer 3 is formed by two protruding end retaining elements 311, 312. The end retaining elements are distributed on opposite transverse sides of the bolt body 202. The spacer 3 comprises a turning device 321 comprising a string indicated in fig. 4. The turning device 321 is located closer to the second end 3E than to the first end 31 IE, 312E.

Reference is made to fig. 8. The turning device 321 of the spacer 3 is adapted to be engaged by the hand of an operator, who, by pulling the turning device subjects the spacer to a lateral force which moves the second end 3E laterally. The turning device 321 allows the operator to keep his/her hand at a distance, so as to avoid a pinch point hazard. When the second end is moved, the first end 31 IE, 312E remains in substantially the same lateral position. Thereby, the spacer 3 is turned from the spacing position around a turning axis TA which is transverse to the longitudinal direction of the bolt body 202. Thereby, a part of the bolt body 20 is moved out through the opening formed between the ends 301E, 302E of the spacer profile. More specifically, the lower of the two clips 301, 302 (fig. 4) is moved away from its engagement with the bolt body. It should be noted that the end retaining elements 311, 312 are distributed in parallel with the turning axis TA. It is understood that the spacer turning axis TA can move as the spacer is turned.

When the spacer 3 is turned, the support of the bolt by the spacer disappears. Thereby, the bolt falls, and the bolt body 202 is allowed to further enter the first hole 1411.

Reference is made also to fig. 9. During the fall of the bolt, the end retaining elements 311, 312 remain on opposite sides of the bolt body 202. Thereby, the spacer 3 is adapted to allow the first end of the spacer, with the end retaining elements 311, 312, to be pinched between the bolt head 201 and the flange 1412 of the first tower section 141. Thereby, the spacer is adapted to dampen the move of the bolt 2 as the bolt moves upon said turning of the spacer.

As exemplified in fig. 10, upon the pinching of the first end of the spacer 3 to dampen the fall of the bolt 2, the bolt may be stationary and resting on the first end of the spacer. Thereafter, the spacer can be completely removed by the turning device 321 being pulled. Thereby, the bolt is allowed to fall a relatively short distance until the head 201 contact the flange 1412.

With reference to fig. 11 - fig. 16, an alternative embodiment of the invention will be described. The embodiment is similar to the one described with reference to fig. 1 - fig. 10, except for some differences as presented below. As understood from fig. 11 - fig. 14, the spacer 3 is designed so that the opening formed between the ends 301E of the spacer profile forms a slot extending, in the spacing position of the spacer (fig. 14), along the longitudinal axis of bolt body.

As illustrated in fig. 11 - fig. 14, the spacer comprises two dampening edges 331 extending, in the spacing position of the spacer, at least partly in the longitudinal direction of bolt body, on opposite sides of the slot between the ends 301E of the spacer profile. The dampening edges 331 are provided on respective flanges 332 of the spacer. The flanges 332 protrude from edges formed by the ends 301E of the spacer profile. The dampening edges 331 are convex. The dampening edges 331 are curved.

As indicated in fig. 14, the spacer 3 comprises a turning device 321 in the form of a holder for a lever (not shown). The lever, which may be in the form of a pin, can be engaged with the holder 321, in order for the spacer to be turned.

Reference is made also to fig. 15 and fig. 16. When the spacer 3 is turned by means of the lever held by the holder 321, the spacer is moved away from partly surrounding the bold body 202. When the spacer is turned, around a turning axis TA, a lower edge of the head 201 of the bolt, in this example a washer thereof, glides along the dampening edges 331. Thereby, the dampening edges 331 contact the bolt head 201 on opposite sides of the bolt body 202, so that, as the spacer is turned, points of contact PC between the dampening edges and the bolt head move along the dampening edges. Thereby, the rotational speed of the turning of the spacer can decide the speed at which the bolt moves downwards. Thereby, the downwards movement of the bolt is dampened.

With reference to fig. 17, steps in a method according to the invention, using any of the bolt and spacer assembly types described with reference to fig. 1 - fig. 16, will be described.

The method comprises positioning SI the spacer 3 on the elongated bolt body 202 of the bolt 2, so that the spacer 3 partly surrounds the bolt body 202. The method further comprises, inserting S2 the penetration end of the bolt body into a first hole 1411 in the flange 1412 of the first tower section 141, so that the head 201 of the bolt is above the penetration end. Thereby, the spacer 3 assumes the spacing position in which the spacer keeps the head and the flange 1412 apart.

Thereafter, the spacer is turned S3 from the spacing position around the turning axis TA which is transverse to the longitudinal direction of the bolt body. Thereby, a part of the bolt body 202 is moved out through the opening formed between the ends 301E, 302E of the spacer profile. Thereby, the bolt is allowed S4 to move under the influence of gravity acting on the bolt so that the bolt body further enters the first hole. Also, as the bolt moves upon said turning of the spacer, the spacer is allowed S5 to contact the bolt head so as to dampen the move of the bolt. Subsequently the bolt is secured, e.g. with a nut screwed against the flange of the second tower section, for a bolted connection of the wind turbine tower sections.

Various embodiments are possible within the scope of the claims.

In some embodiments, a spacer as the one described with reference to fig. 1 - fig. 10 is placed in the opposite direction, so that the end retaining elements 311, 312 is in contact with the tower section flange 1412, and the other end of the spacer is in contact with the bolt head. Thereby, the turning device 321 comprising the string could be closer to the bolt head than to the tower section flange. Thereby, when the spacer is turned, the end retaining elements 311, 312 may remain in contact with the bolt body 202. Thereby, the fall of the bolt 2 may be to be dampened by friction between the retaining elements 311, 312 and threads of the bolt body.

Fig. 18 - fig. 20 shows a spacer similar to the spacer in the embodiment described with reference to fig. 1 - fig 10, but with a difference as follows: The two clips 301, 302 are separated by an intermediate part 303 in the form of a bar.

Fig. 21 shows a bolt and spacer assembly similar to the bolt and spacer assembly in the embodiment described with reference to fig. 1 - fig 10, but with a difference as follows: There is a single clip 301.

Fig. 22 shows a bolt and spacer assembly similar to the assembly in the embodiment in fig. 21, but with a difference as follows: There are no end retaining elements 311. Instead, both ends of the spacer 3 form respective single, part circular end surfaces adapted to abut the bolt head and the tower section flange respectively. Nevertheless, the turning device 321 is as in the embodiment in fig. 21 located closer to one of the ends than to the other of the ends. Therefore, it is possible to pull the turning device 321 so as to move one of the ends laterally. Upon the fall of the bolt, the other end may remain at the bolt body 202, to get pinched between the bolt head 201 and the tower section flange, to dampen the fall of the bolt.

As will be understood by those skilled in the present field of art, numerous changes and modifications may be made to the above described and other embodiments of the present invention, without departing from its scope as defined in the appending claims.

Claims

1. A bolt and spacer assembly comprising a bolt (2) comprising a head (201) and an elongated bolt body (202), the bolt body being terminated at a penetration end (203) located at a distance from the head,

- which bolt body (202) is adapted to penetrate a first hole (1411) in a first wind turbine tower section (141), and to penetrate a second hole in a second wind turbine tower section (142) for a bolted connection of the wind turbine tower sections,

- wherein the bolt and spacer assembly further comprises a spacer (3) adapted to assume, when the penetration end is inserted into the first hole and the head is above the penetration end, a spacing position in which the spacer by contact with the head and the first wind turbine tower section keeps the head and the first wind turbine tower section apart,

- wherein the spacer presents, in the spacing position and as seen along a longitudinal direction of the bolt body, an open profile such that an opening is formed between ends (301E, 302E) of the profile so that the spacer (3) partly surrounds the bolt body (202), characterised in that the spacer is adapted to be turned from the spacing position around a turning axis (TA) which is transverse to the longitudinal direction of the bolt body so that at least a part of the bolt body is moved out through the opening formed between the ends (301E, 302E) of the spacer profile, so as to allow the bolt body to further enter the first hole as the bolt moves under the influence of gravity acting on the bolt, and in that the spacer is adapted to contact the bolt (2) so as to dampen the move of the bolt as the bolt moves upon said turning of the spacer.

2. A bolt and spacer assembly according to claim 1, wherein said adaption of the spacer to contact the bolt (2) comprises the spacer being adapted to contact the bolt head (201) so as to dampen the move of the bolt.

3. A bolt and spacer assembly according to any one of the preceding claims, wherein the spacer (3) extends, in the spacing position and in the longitudinal direction of the bolt body (202), between a first end (31 IE, 312E) and a second end (3E) of the spacer, wherein said adaption of the spacer to contact the bolt comprises the spacer being adapted to allow the first end (31 IE, 312E) of the spacer to be pinched between the bolt head and the first tower section (141).

4. A bolt and spacer assembly according to any one of the preceding claims, wherein the spacer (3) extends, in the spacing position and in the longitudinal direction of the bolt body (202), between a first end (31 IE, 312E) and a second end (3E) of the spacer, wherein the spacer is adapted so that during said turning of the spacer the second end moves further than the first end, wherein the first end (31 IE, 312E) of the spacer (3) is formed by two protruding end retaining elements (311, 312) distributed, in the spacing position of the spacer, in parallel with the turning axis and on opposite transverse sides of the bolt body (202).

5. A bolt and spacer assembly according to any one of the preceding claims, wherein the spacer comprises two clips (301, 302) which, in the spacing position of the spacer, partly surround the bolt body (202) along a transverse angular interval (Al) which is larger than 180 degrees, and which, in the spacing position of the spacer, are separated in the longitudinal direction of the bolt body (202) by an intermediate part (303) which is not adapted to partly surround the bolt body (202) along a transverse angular interval which is larger than 180 degrees.

6. A bolt and spacer assembly according to any one of the preceding claims,

- wherein the opening formed between the ends (301E) of the spacer profile forms a slot extending, in the spacing position of the spacer, along the longitudinal axis of bolt body,

- wherein the spacer comprises two dampening edges (331) extending, in the spacing position of the spacer, at least partly in the longitudinal direction of bolt body, on opposite sides of the slot,

- wherein the spacer being adapted to contact the bolt, as the bolt moves under the influence of gravity upon said turning of the spacer, comprises the dampening edges (331) being adapted to contact the bolt on opposite sides of the bolt body, so that, as the spacer is turned, points of contact (PC) between the dampening edges and the bolt move along the dampening edges.

7. A bolt and spacer assembly according to claim 6, wherein the dampening edges (331) are provided on respective flanges (332) of the spacer.

8. A bolt and spacer assembly according to any one of claims 6-7, wherein the dampening edges (331) are curved and convex as seen along the turning axis (TA) of the spacer.

9. A bolt and spacer assembly according to any one of claims 6-8, wherein the dampening edges (331) being adapted to contact the bolt comprises the dampening edges being adapted to contact the bolt head (201).

10. A bolt and spacer assembly according to any one of the preceding claims, wherein said adaption of the spacer to contact the bolt head so as to dampen the move of the bolt comprises allowing the move of the bolt (2) to be dampened by friction between the spacer and threads of the bolt body.

11. A combination of a bolt and spacer assembly according to any one of the preceding claims, a first wind turbine tower section (141), and a second wind turbine tower section (142), wherein the bolt body (202) of the bolt (2) is adapted to penetrate a first hole (1411) in the first wind turbine tower section (141), and to penetrate a second hole in the second wind turbine tower section (142) for a bolted connection of the wind turbine tower sections.

12. A spacer (3) for a bolt and spacer assembly according to any one of claims 1-10.

13. A method for connecting a first tower section (141) for a wind turbine to a second tower section (142) for the wind turbine, comprising positioning a spacer (3) on an elongated bolt body (202) of a bolt (2) wherein the spacer presents, as seen along a longitudinal direction of the bolt body, an open profile such that an opening is formed between ends (301E, 302E) of the profile so that the spacer (3) partly surrounds the bolt body (202), and inserting a penetration end (203) of the bolt body into a first hole (1411) in the first tower section (141), so that the head (201) of the bolt is above the penetration end,

- wherein the spacer (3), positioned on the bolt body (202) of the bolt the penetration end of which is inserted into the first hole, assumes a spacing position in which the spacer by contact with the bolt head and the first wind turbine tower section keeps the head and the first wind turbine tower section apart, characterised by turning the spacer from the spacing position around a turning axis (TA) which is transverse to the longitudinal direction of the bolt body so that at least a part of the bolt body is moved out through the opening formed between the ends (301E, 302E) of the spacer profile, so as to allow the bolt body to further enter the first hole as the bolt moves under the influence of gravity acting on the bolt, allowing, as the bolt moves upon said turning of the spacer, the spacer to contact the bolt so as to dampen the move of the bolt, and subsequently securing the bolt for a bolted connection of the wind turbine tower sections wherein the bolt body (202) penetrates the first hole (1411) and a second hole in the second wind turbine tower section (142).

14. A method according to claim 13, wherein the spacer (3) extends, in the spacing position and in the longitudinal direction of the bolt body (202), between a first end (31 IE, 312E) and a second end (3E) of the spacer, wherein said contact of the spacer so as to dampen the move of the bolt comprises allowing the first end (31 IE, 312E) of the spacer to be pinched between the bolt head and the first tower section (141).

15. A method according to any one of claims 13-14,

- wherein the opening formed between the ends (301E) of the spacer profile forms a slot extending, in the spacing position of the spacer, along the longitudinal axis of bolt body,

- wherein the spacer comprises two dampening edges (331) extending, in the spacing position of the spacer, at least partly in the longitudinal direction of bolt body, on opposite sides of the slot, - wherein said contact of the spacer so as to dampen the move of the bolt comprises the dampening edges (331) contacting the bolt on opposite sides of the bolt body, so that, as the spacer is turned, points of contact (PC) between the dampening edges and the bolt move along the dampening edges.