Assembly including a first member, a second member and a connector, and method for assembling said assembly

Abstract

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved assembly. [Solution] The present invention relates to an assembly comprising a first member and a second member, the second member having a fork-shaped cross-section consisting of a body and two substantially parallel walls each having at least one through hole, the first member being disposed between the two walls of the second member and having a through hole, the through hole of the first member and the through hole of the second member forming a channel, the assembly further comprising a connector axially insertable into the channel to an end position and continuously expandable radially relative to the channel to connect the first member and the second member to each other, the connector, in its expanded state, pressing the first member against the body of the second member to form a pre-tensioned connection between the first member and the second member.

Description

[Technical field]

[0001] The present invention relates to an assembly that includes a first member and a second member, and a connector for connecting the first member and the second member to each other.

[0002] The invention further relates to a method of assembling such an assembly of a first member and a second member, each member including at least one through hole. [Background technology]

[0003] The invention is particularly suitable for offshore applications, e.g. for connecting a wind turbine to a monopile, a wind turbine to a transition piece, a transition piece to a monopile, as well as for connections between members of a monopile or a wind turbine and a jacket connection.

[0004] According to prior art applications offshore, the members of such assemblies are provided with flanges which are connected using bolts of rather large size. Currently, M72 bolts are used to connect the wind turbine tower to the monopile or transition piece. In a first step, these bolts are electrically tightened to 8.000 Nm. In a second step, the preload is increased to 22.000 Nm with a hydraulic tool. The bolts themselves are heavy and the tools for tightening the bolts are also heavy and difficult to operate.

[0005] The actual preload on the bolt after some settling time is difficult to predict and control and can vary widely. Although it is not clear exactly what factors affect the torque-tension relationship of a bolt, it can be concluded that installing a bolt using a "constant torque" method will not achieve satisfactory results. Similar problems arise with tensioning the system for bolting. The preload on the bolt must be checked and adjusted periodically, requiring significant maintenance work periodically.

[0006] Furthermore, the bolts are placed around the entire circumference of the flange, leaving only very limited gaps between adjacent bolts, and connections using bolted flanges are not sufficiently scalable to meet the ever increasing demands due to larger wind turbines and deeper oceans in which they are installed.

[0007] Patent Document 1 proposes an improved assembly for connections using flanges connected by bolts. This improved prior art assembly: - a first section and a second section, each section including a longitudinal axis; a fastener configured to fasten the first section and the second section; - at least one of the first section and the second section includes a body configured to be engaged by a fastener; The fixture comprises an abutment and a radially displaceable actuator. The actuator is radially displaceable relative to the longitudinal axis of the section containing it. This allows the actuator itself to be used as part of the clamp. During the radial displacement of the actuator, the inclined surface of the actuator engages a specially machined surface of the first section, gradually increasing the clamping force connecting the first and second sections. Although the assembly of the '631 patent already offers a significant improvement over the above-described prior art connections using bolted flanges, the applicant now proposes a further improvement. The radial displacement of the actuator required a significant force due to the clamping action. Moreover, sections with specially designed contact surfaces were required.

[0008] US Patent No. 5,399,633 is directed to an expansion pin system for the construction of a wind turbine structural tower and is considered the closest prior art. The patent discloses, in the terms of the present invention, a first and a second member, the second member having a fork-shaped cross section consisting of a body and two substantially parallel walls each including at least one through hole, the first member being disposed between the two walls of the second member and having a through hole, the through hole of said first member and the through hole of the second member being aligned to form a channel. The expansion pin can be interpreted as a connector that is axially insertable into said channel to a terminal position and is continuously expandable in a radial direction relative to said channel to connect the first and second members to each other. When the expansion pin system is inserted into the channel, it results in the alignment of the through holes of the first and second members.

[0009] US 6,399,433 discloses several adjustable fixing devices arranged between the segments of a cylindrical shell of a stator of a generator of a wind turbine. These adjustable fixing devices are configured to press the segments together in a circumferential direction to fix the segments in a given position. The device of US 6,399,433 does not disclose a second member with a fork-shaped cross section consisting of a body and two substantially parallel walls with a through hole, the first member being arranged between the two walls of the second member.

[0010] The expansion bolt of US Pat. No. 5,399,633 and the anchor bolt disclosed in US Pat. No. 5,399,633 are recognized as further prior art. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2018 / 139929 [Patent Document 2] US Patent Application No. 2008 / 080946 [Patent Document 3] European Patent Application Publication No. 2187506 [Patent Document 4] U.S. Pat. No. 1,120,409 [Patent Document 5] European Patent Application Publication No. 3171040 Summary of the Invention [Problem to be solved by the invention]

[0012] It is an object of the present invention to provide an improved assembly over the prior art, whereby at least one of the above mentioned problems is obviated. [Means for solving the problem]

[0013] The object of the present invention is to provide an assembly according to claim 1, a first member and a second member, - the second member has a fork-shaped cross-section consisting of a body and two substantially parallel walls each including at least one through hole; - the first member is disposed between two walls of the second member and has a through hole; - a first member and a second member, the through hole of the first member and the through hole of the second member forming a channel; - a connector axially insertable into said channel to a terminal position and continuously expandable radially relative to said channel to connect the first member and the second member to one another; The connector is achieved by an assembly which, in its expanded state, presses the first member against the body of the second member to define a pretensioned connection between the first and second members.

[0014] As a result of the pretensioned connection between the first and second members, the load variations through the connector are significantly reduced resulting in very low fatigue damage levels compared to non-pretensioned connections.

[0015] The patent does not disclose that the connector, in its expanded state, presses the first member against the body of the second member to form a pretensioned connection between the first and second members. After all, a male flange end, which can be considered as the first member, is placed between the two flanges of the female end of the connector, and the free end of said male flange end is placed a little away from the connector. From the point of view of hole alignment, it makes sense that the male flange end, i.e. the first member, has a free end, as obtained by the expansion pin of the patent. However, perfect alignment is not desired in view of obtaining an optimal pretension of the connection between the first and second members.

[0016] In contrast to the assembly of the '891 patent, in a first step the user inserts the connector into the channel to an end position, followed by a further step of continuously expanding said connector radially relative to said channel, thereby connecting the first and second members to each other. In this way the connector can be accurately and easily placed in the channel by the user with very limited fuss or force. Only when the connector is placed in its desired end position, is it expanded in the channel to connect the first and second members to each other. The use of the connector according to the invention also makes unnecessary specially machined contact surfaces, with a slope corresponding to the slope of the radially displaceable actuator.

[0017] Contrary to older prior art bolted flanges, large size (e.g. M72) bolts are unnecessary. Also, the body can be less bulky than flanges including through holes to accommodate the bolts. As a result, the assembly according to the invention requires less material and is therefore more compact, lighter and more elegant. While thicker parts need to be forged, smaller parts may be rolled, potentially allowing the parts to be formed with alternative and more attractive manufacturing methods. Also, the assembly according to the invention is scalable, offering the opportunity to place multiple connectors axially on the part.

[0018] An additional advantage of the proposed assembly over bolted flanges is that these flanges, which would otherwise impose significant mass outside the path of force transmission during the use of a hammer to drive the assembly into the ground, can result in bending of the flange necks. These bending stresses result in significantly reduced life of the welds in these flanges when currently installed with conventional impact hammers.

[0019] Another further advantage of the proposed assembly over bolted flanges is that it can be applied to connect members below the waterline, while elongated members of limited length may be used, allowing smaller vessels to transport them to the desired location for the offshore structure.

[0020] Sequential tightening of bolts in bolted flanges, as mentioned above, is typically tightened in multiple steps and is very time-consuming and labor-intensive. The proposed assembly is less labor-intensive and time-consuming than connections with bolted flanges.

[0021] According to a preferred embodiment, in its expanded state, the connector presses against a face of the through hole of the second member that faces away from the body of the second member to form a pretensioned connection between the first member and the second member.

[0022] According to a further preferred embodiment, in the expanded state of the connector, the connection between the first and second members is pretensioned and the through-hole of the first member is arranged offset with respect to the through-hole in the second member. As mentioned above, said through-hole of the first member and the through-hole of the second member form a channel, which means that said through-holes are positioned such that they are "substantially" aligned. However, the preferred offset can ensure that a slight misalignment of the through-hole of the first member with respect to the through-hole of the second member always remains. This is an advantage, since the offset, i.e. the slight misalignment in the channel, ensures that the connection between the first and second members can be optimally pretensioned. After all, the connector is configured to expand in the channel, the connector pressing the first member against the body of the second member. In order to optimally press the first member towards the body of the second member, it is beneficial if the side of the connector that is directed towards the body does not come into contact with the inner wall of the through-hole in the parallel wall of the second member. In this way, the side of the connector facing towards the main body can fully transmit its compressive force to the first member which is pressed towards and against the body of the second member to obtain the desired pre-tension.

[0023] According to a preferred embodiment, the connector comprises: a compressed state in which the connector is sized to be freely inserted and removed from the channel; - a connected state, in which the connector is expanded into the channel to connect the first member and the second member to one another.

[0024] In compression, the play between the connector and the inner wall of the channel allows the connector to be easily inserted into the channel. A high axial clamping force is then applied by the connector, which has the advantage that the assembly is less susceptible to load changes. This is well understood when compared to how a bolted joint carries the load directly. In applications where an untightened or loose bolt would fail in a short period of time, a properly pretensioned bolt can survive. The bolt "senses" only a small portion of the applied load.

[0025] The present invention is further directed to a method of assembling a first member and a second member, each member including at least one through hole, the method comprising: - positioning through holes in the first and second members to form a channel; - inserting the connector into the channel to a terminal position; - continuously expanding the connector radially relative to the channel, thereby connecting the first member and the second member to one another. Including, - The expanded connector presses the first member against the body of the second member to form a pre-tensioned connection between the first and second members.

[0026] In a preferred embodiment, the above-mentioned method steps are preceded by a step of positioning at least one of the first and second members by lifting them, a lifting equipment engaging at least one of the through holes of the first or second member, respectively. Since the connectors can be separate units that are only inserted into channels during assembly, the through holes of the first and second members can be effectively used while lifting them.

[0027] In a further preferred embodiment of the method, a rod-shaped member, preferably a rod, is placed through at least one of the through holes to connect the first member or the second member, respectively, to a lifting equipment.

[0028] Further preferred embodiments are the subject matter of the dependent claims.

[0029] In the following description, preferred embodiments of the present invention will become more clear with reference to the drawings. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic diagram of an offshore wind turbine tower supported by monopiles. [Diagram 2] FIG. 1 is a cross-sectional view of a flange connection according to the prior art. [Diagram 3] FIG. 1 is a perspective view of an assembly according to a first embodiment of the present invention; [Figure 4] FIG. 4 is a cross-sectional perspective view of the assembly shown in FIG. [Diagram 5] FIG. 1 is a perspective view of a clamp according to a first embodiment. [Figure 6] FIG. 6 is a detailed cross-sectional view of the clamp of FIG. 5. [Figure 7] FIG. 6 is an exploded perspective view of the clamp of FIG. 5. [Figure 8] 1A-1D are cross-sectional views of sequential steps for assembling an assembly according to a first embodiment. [Figure 9] 1A-1D are cross-sectional views of sequential steps for assembling an assembly according to a first embodiment. [Figure 10] 1A-1D are cross-sectional views of sequential steps for assembling an assembly according to a first embodiment. [Figure 11] 1A-1D are cross-sectional views of sequential steps for assembling an assembly according to a first embodiment. [Figure 12] FIG. 1 is a perspective view of the inside of a wind turbine monopile. [Figure 13]FIG. 4 is a cross-sectional view of an assembly according to a second embodiment of the present invention. [Figure 14] FIG. 4 is a cross-sectional view of an assembly according to a third embodiment of the present invention. [Figure 15] FIG. 11 is a cross-sectional view of an assembly according to a fourth embodiment of the present invention. [Figure 16] FIG. 10 is a cross-sectional view of an assembly according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] An example of an offshore structure including multiple connections C to which the assembly according to the invention may be applied is shown in Figure 1. An offshore wind turbine tower 1 is supported by a supporting substructure 2 in Figure 1 integrated as a monopile 3 with a transition piece 4. It will be understood by those skilled in the art that similar connections exist for alternative supporting substructures 2 such as jackets (not shown).

[0032] The connections C may be applied between separate members 8 of the monopile 3, between the monopile 3 and the transition piece 4, between the transition piece 4 and the turbine tower 1, between members 9 of the turbine tower 1, and between the rotor blades 6 and the hub of the rotor.

[0033] In use, the wind turbine 5 is oriented so that the rotor blades 6 are optimally driven by the available wind power. The rotor blades 6 drive a generator (not shown) in the nacelle 7, which produces electricity. The wind turbine 5 generates alternating loads on any connection C in the structure, and depending on the wind direction, certain parts of the connections C must absorb most of the load.

[0034] According to the prior art (see FIG. 2), an assembly 10 configured to connect a first member 11 and a second member 12 typically includes flanges 13, 14. These flanges 13, 14 are provided with aligned through holes 15, 16. A bolt 17 and nut 40 assembly is then placed through the aligned through holes 15, 16 and used to clamp the flanges 13, 14 together. As already explained, current M72 bolts 17 are used to connect a wind turbine tower 1 to a monopile 3 or transition piece 4. The bolts 17 themselves are heavy, and the tools for tightening the bolts 17 are also heavy and difficult to operate. Moreover, the preload on the bolts 17 must be regularly checked and adjusted, requiring significant maintenance operations periodically.

[0035] The flanges 13, 14 need to be relatively thick in both axial directions to accommodate the through holes 15, 16 and to create an effective preload between the flanges 13, 14. They also need to be wide (radially) to prevent the flanges from becoming a substantial lever when significant tensile loads are applied to the steel wall to which they are welded.

[0036] The assembly according to the invention comprises a first member 18 and a second member 19, each of which comprises at least one through hole 20-22. The through holes 20-22 may be arranged directly in the first member 18 and the second member 19, and therefore the flanges 13, 14 shown in FIG. 2 are unnecessary. This has several advantages, one of which is a saving in material. The second member 19 is made from the amount of material that is roughly present in one of the flanges 13, 14 of FIG. 2 as well. However, the material required for the first flange 13 in FIG. 2 is completely saved. Also, since there are no flanges 13, 14, the weight outside the line of force transmission through the assembly is less. Moreover, laborious and expensive welding operations are suppressed.

[0037] The taper angle at the bottom of member 19 and the taper angle at the top of member 18 allow a certain amount of oval shape in either member 18 or member 19 to be forced back into a circle under gravity by pressing member 19 into member 18.

[0038] In the illustrated embodiment, the first member 18 includes one through hole 20 and the second member includes two through holes 21, 22. In assembly, the through holes 20-22 of the first member 18 and the second member 19 together form a channel 23. A connector 24 is axially insertable into said channel 23 to a terminal position and is continuously radially expandable relative to said channel 23 to connect the first member 18 and the second member 19 to one another.

[0039] The connector 24 includes a compressed state (shown in Figures 9 and 10) in which the connector 24 has a size that allows it to be freely inserted and removed from the channel 23, and a connected state (shown, for example, in Figures 4 and 11) in which the connector is expanded within the channel 23 to connect the first member 18 and the second member 19 to each other.

[0040] The description in this paragraph relates to the orientation shown in FIG. 11, but those skilled in the art will understand that the same principles can be applied in other orientations, such as sideways or upside down with respect to FIG. 11. In the connected state shown in FIG. 11, the connector 24 contacts with its lower surface a surface 41 formed on the lower surface of the respective through-hole 21, 22 of the second member 19. The upper surface of the connector 24 contacts a surface 42 arranged on the upper surface of the through-hole 20 in the first member 18. In the expanded state of the connector 24, the connector 24 presses the surface 41 of the second member 19 in a direction away from the surface 42 of the first member 18. As a result, the second member 19 is pressed downwards against the first member 18 and a clamping contact is formed between the surface 43 formed by the upper surface of the first member 18 and the surface 44 formed by the second member 19. Thus, by expanding the connector 24, a pretensioned connection between the first member 18 and the second member 19 can be formed. Surfaces 41, 42, 43, 44 are best seen in Figure 8. By having sufficient pre-tension, the load fluctuations through the connector 24 are significantly reduced resulting in very low fatigue levels.

[0041] The connector 24 includes at least one extension block 25, at least one wedge 26, and an actuator 27 configured to displace the wedge 26 relative to the extension block 25. The wedge 26 has an angled surface 28 facing the at least one extension block 25.

[0042] The connector 24 preferably includes at least one wedge 26 disposed between the two expansion blocks 25, and more preferably, the connector 24 includes two wedges 26. In the illustrated embodiment, the two wedges 26 are disposed between the two expansion blocks 25. The two wedges 26 are disposed symmetrically, with the slopes of their inclined surfaces 28 facing away from each other.

[0043] The actuator 27 can be a bolt 29 that engages in a threaded recess 30 of the wedge 26. Optionally, a washer 38 can be placed between the head of the bolt 29 and the wedge 26. By turning the bolt 29, the wedges 26 can be pulled together over a distance corresponding to the thread of the bolt 29. When two wedges 26 are used, the displacement is divided over both wedges 26. The thread can be interpreted as a first transmission, and the division over both wedges can be interpreted as a second transmission. Through the inclined surface 28, which can be interpreted as a third transmission, the connector 24 is expanded, i.e. when the wedges 26 move towards each other, the expansion blocks 25 are pressed outwards against each other. One of the expansion blocks 25 engages with a face 41 of the second member 19, i.e. with the lower expansion block 25 shown in FIG. 11. The other expansion block 25, i.e. the upper expansion block 25 shown in Figure 11, engages with face 42 of the first member 18. In this way, when the expansion blocks 25 are pressed outwardly towards each other, the pretensioned connection between the first member 18 and the second member 19 described above can be formed.

[0044] The inclined surface 28 of the wedge 26 may include an inclination of an angle of less than 15°, preferably less than 10°, more preferably less than 8°, and most preferably less than 6° with respect to the displacement direction of the wedge 26. This displacement direction coincides with the longitudinal direction of the bolt 29. By providing a relatively flat angle of inclination, the axial clamping force Fc, after its force resolution, results in only a very limited radial force component. The relatively small value of the radial force component is generally smaller than the friction at the contact surface between the wedge 26 and the clamping block 25, resulting in a self-locking contact between the wedge 26 and the clamping block 25 in the connected state. As a result, the wedge 26 remains in place even if the bolt 29, which forms the actuator 27 for initially displacing the wedge 26, is loosened or even removed. Although the bolt 29 preferably remains tightened, this self-locking property prevents the bolt 29 from experiencing stress variations during use. In this way, a reliable and fail-safe assembly is provided.

[0045] The expansion block 25 has a surface 31, at least a portion 32 of which is a contact surface with the wedge 26 that is oriented to coincide with the inclined surface 28 of said wedge 26. When the orientations of the contact surface and the inclined surface 28 are substantially equal, a reliable mating interface is obtained.

[0046] If only a portion 32 of the surface 31 is the contact surface, the contact surface may remain constant over the range of displacement of the wedge 26. When the wedge 26 shown on the right in Figures 5-7 is moved inwardly and its front end 39 passes the edge 40 of the portion 32, the contact surface does not increase any further.

[0047] As can be seen well in Fig. 3 and Fig. 12, the first member 18 and the second member 19 are overlapping tubular members, the through holes 20-22 being aligned radially with respect to the tubular members to form a radially extending channel 23. The first member 18 and the second member 19 have respective longitudinal axes 33, 34 that are at least parallel and preferably coincident (see Fig. 3). In the prior art situation shown in Fig. 2, the nut 40 had to be accessed by means of a tool. However, according to the present invention, an airtight platform 37 can be provided without hindering access to the connection between the first member 18 and the second member 19. On the contrary, it is precisely this airtight platform 37 that can provide a comfortable support for the user to easily place the connector 24 in the respective channel 23.

[0048] According to the illustrated preferred embodiment, a symmetrical force transmission can be obtained if the second member 19 has a fork-shaped cross-section consisting of a body 35 and two substantially parallel walls 36, each of which contains at least one through hole. In this embodiment, the first member 18 is arranged between two walls 36 of the second member 19 having through holes 21, 22, said through hole 20 of the first member 18 and the through holes 21, 22 of the second member 19 being positioned to form a channel 23. The arrows in Fig. 11 show how the clamping force Fc is distributed symmetrically.

[0049] The channels 23 preferably have an elongated cross-section extending longitudinally of at least one of the first member 18 and the second member 19. For channels having a circular shape, such an elongated cross-sectional shape provides a relatively large amount of material between consecutive channels 23 when multiple channels 23 and connectors 24 are disposed along the circumference of the first member 18 and second member 19.

[0050] In a second embodiment of the invention, the wedges 26' are inclined only on one side, i.e. the upper side in FIG. 13, with respect to the displacement direction of the wedges 26'. The other side of each wedge 26', i.e. the lower side in FIG. 13, is substantially parallel to the displacement direction of the wedges 26'. The extension block 25' has two substantially parallel faces, which allows the extension block 25' to be placed ahead of the wedges 26' and the other extension blocks 25 in the assembly. The extension block 25' also better facilitates disassembly.

[0051] A third embodiment of the invention, in which a single wedge 26 is applied, is shown in FIG.

[0052] A fourth embodiment of the invention is shown in Figure 15. This embodiment combines a single wedge 26 according to the embodiment of Figure 14 with an extension block 25' having two substantially parallel faces according to the embodiment of Figure 13.

[0053] In one embodiment (not shown), the clamp blocks 25 may be connected by a flexible member that surrounds the space between the clamp blocks 25 in which the wedges 26 are located. Lubricant may be added into such enclosed space.

[0054] According to a fifth embodiment of the invention, shown in FIG. 16, the second member 19 is integrated as an assembly rather than as a monolithic element. The fork-shaped cross section is formed by the assembly of the body 35 with two substantially parallel walls 36, which extend partially along this body 35 and are connected to both sides of the body 35. The walls 36 may be formed by a number of plates 45. The plates 45 may include through holes 46 to allow a pin 47 to pass through said plates 45 and through corresponding through holes 48 in the body 35 of the second member 19. In the illustrated embodiment, bolts 49 and washers 50 are used to clamp the plates 45 forming the side walls 36 to the body 35. The bolts 49 are preferably arranged inside the tubular first member 18 and the second member 19 to allow easy access. There is a moderate pretension between the body 35 and the plates 45 arranged on both sides of the body 35. When the connector 24 is clamped, the main load transfer path, however, is through tension applied through the plates 45, which are transferred to shear forces in the pins 47. The connector 24, both plates 45 on the inner and outer faces of the second member 19, and the pins 47 all form part of the pre-tensioned load transfer path. As a result, very low load variations are felt by these components when an external load is applied to the connection. In the preferred embodiment, each connector 24 is associated with one inner plate 45 and one outer plate 45. The clamping action of the fifth embodiment is similar to the other embodiments.

[0055] Relative to the second member 19 including an integral fork-shaped cross-section, the assembly according to the fifth embodiment has several advantages and disadvantages.

[0056] A drawback of the fifth embodiment is the open structure formed by the multiple separate plates 45. This may limit the main application of the fifth embodiment to so-called airborne conditions, where the structure is not continuously exposed to salt spray as it is in the so-called splash zone. When used in offshore applications, the fifth embodiment is preferably applied well above the splash zone, i.e. well above sea level. However, this fifth embodiment may also find use in the splash zone or even below, if a seal is used between the multiple separate plates 45. The separate plates 45 may also be designed such that the plates overlap each other at the contact surface to adjacent plates, with the overlap also sealing the contact surface to prevent water and / or air penetration.

[0057] On the other hand, the fifth embodiment also includes some important advantages.

[0058] Firstly, there is no need to make solid rings in the required sizes, which would typically require forging processes that can only be applied by a limited number of highly specialized companies. The plate 45 and pin 47 according to the fifth embodiment can be easily made by most metal workshops, allowing the main part of the connection to be made by a large number of companies.

[0059] Secondly, when a solid ring is forged, forming the grooves therein takes time and results in a significant amount of steel being removed in the machining step, however, there is the benefit that in the creation of the plates 45, it is not necessary to remove material between the plates 45 as in the case of a solid forging which requires machining to remove the grooves.

[0060] Third, large forged rings are heavy and bulky, creating logistical challenges and costs. Because plates 45 and pins 47 are easy to transport and they can be made by a large number of different companies, transportation can be minimized if a local metal shop makes these parts.

[0061] Fourth, the forged and machined ring needs to be welded to the second part 19, which can deform the face 44 of said second part 19. This deformation can result in so-called waviness, which can have a detrimental effect on the structural integrity of the connection, since the resulting gaps need to be closed using prestress applied by the connector 24.

[0062] Finally, increased flexibility is obtained if some plates 45 provide additional functions, such as alignment functions.

[0063] In the illustrated embodiment, the first member 18 and the second member 19 are members of an offshore structure, more particularly of an offshore wind turbine structure 1. Each of the first member 18 and the second member 19 may be an upright member of a monopile 3. However, it is explicitly stated that the invention is not limited to offshore applications. In particular, the fifth embodiment described above is particularly suitable for use in onshore wind turbine applications. Onshore, the combination of the limited diameter of tubulars that can be transported on roads, the ever increasing tower heights to capture stronger winds, and the ever increasing power ratings of wind turbines results in connections between tubulars that are subjected to very high load levels. These load levels may even exceed those of typical L-flanges. Compared to conventional L-flange connections, the absence of two welds between the flange and the tubular and the absence of the expensive flange itself makes the invention, and especially the fifth embodiment, a commercially attractive solution even at lower load levels.

[0064] Alternatively, one of the first member 18 and the second member 19 is a rotor blade 6 of the wind turbine 1, and the other of the first member 18 and the second member 19 is arranged on a hub, and as an example, said first member 18 and the second member 19 can be arranged on a pitch bearing (not shown) attached to the hub. Such pitch bearings are known in the art and include ball bearings or roller bearings. The connection between the bearing and the blade can be established via either the inner or outer raceway of the bearing in case of a two-raceway bearing. Figure 1 shows this connection C, as well as many other places where a similar assembly can be applied as connection C.

[0065] A method of assembling a first member 18 and a second member 19, each of which includes at least one through hole 20-22 according to the present invention, comprises: - positioning the through holes 20-22 of the first member 18 and the second member 19 so as to form a channel 23 (step from FIG. 8 to FIG. 9 ); - inserting the connector 24 into the channel 23 up to a terminal position (step from FIG. 9 to FIG. 10 ); - continuously expanding said connector radially relative to said channel, thereby connecting first member 18 and second member 19 to each other (step from FIG. 10 to FIG. 11).

[0066] Although not shown, the method of assembly is preceded by a step of positioning at least one of said first member 18 and second member 19 by lifting them, and a lifting equipment (not shown) engages at least one of the through holes 20-22 of said respective first member 18 or second member 19. A rod-shaped member, preferably a rod, may be placed through at least one of the through holes 20-22 to connect the respective first member 18 or second member 19 to the lifting equipment.

[0067] The same through holes 20-22 may also be used to engage an installation tool.

[0068] While they represent preferred embodiments of the present invention, the above described embodiments are intended to be merely illustrative of the present invention and in no way limit the scope of the present invention. Although Figure 1 shows an offshore wind turbine tower structure, the assembly according to the present invention is not limited to offshore applications, nor is it limited to only wind turbine applications.

[0069] In the description of the illustrated embodiment, it can be seen that the lower member is designated as the first member 18 and the upper member is designated as the second member 19. It will be understood by those skilled in the art that the lower member may be construed as the second member 19 and the upper member as the first member 18 within the scope of the present invention.

[0070] When features described in the appended claims are followed by reference signs, it will be understood that such signs are included merely to enhance the comprehension of the claims and in no way serve to limit the scope of the claims. The scope of the present invention is defined solely by the following claims. [Explanation of symbols]

[0071] 1. Offshore Wind Turbine Tower 2 Supporting foundation structure 3. Monopile 4. Transition Piece 5. Wind Turbines 6 Rotor Blades 7 Nacelle 8. Materials 9. Materials 11 First Component 12 Second member 13 Flange 14 Flange 15 Through Hole 16 Through holes 17 Volts 18 First Component 19 Second member 20 through holes 21 Through hole 22 Through hole 23 Channels 24 Connectors 25 Expansion Blocks 25′ Extension Block 26 Wedge 26' Wedge 27 Actuator 28 Slope 29 Volts 30 Threaded Recess 31 Surface 32 Part of the surface 33 Longitudinal axis 34 Longitudinal axis 35 Main unit 36 Wall 37 Airtight Platform 38 Washer 39 Front end 40 Nut 40a Edge 41 sides 42 sides 43 sides 4 sides 45 Plate 46 Through Hole 47 pin 48 through holes 49 Volts 50 Washer

Claims

1. An assembly comprising a first member (18) and a second member (19) which are members of a wind turbine structure and a connector (24), the second member (19) has a fork-shaped cross section and comprises a body (35) disposed between two substantially parallel walls (36) each having at least one through hole (21, 22); The first member (18) is disposed between the two walls (36) of the second member (19) having the through holes (21, 22), the through hole (20) of the first member (18) and the through holes (21, 22) of the second member (19) form a channel, the channel (23) having an elongated cross section extending in the longitudinal direction of both the first member (18) and the second member (19); the entire connector (24) is axially insertable into the channel (23) from one end of the channel (23) to a terminal position located at the other end of the channel (23), and the connector (24) is radially expandable continuously relative to the channel (23) to connect the first member (18) and the second member (19) to each other; said connector (24), in an expanded state, presses said first member (19) against a surface (44) of said body (35) of said second member (19) in a radial direction relative to said channel (23) to form a clamping contact and thus a pretensioned connection between a surface (43) of said first member (18) and said body (35) of said second member (19); The connector (24) Two expansion blocks, two wedges having inclined surfaces facing the two expansion blocks; an actuator configured to displace the wedge relative to the expansion block; Equipped with the connector (24) comprises two of the wedges disposed between two of the expansion blocks; An assembly characterized in that the two wedges are arranged symmetrically with respect to the longitudinal direction of the channel (23) with the inclinations of the inclined surfaces of the two wedges oriented away from each other, thereby resulting in a symmetrical distribution of forces acting on the expansion block in a direction perpendicular to the longitudinal direction of the channel (23).

2. the connector (24) in the expanded state presses against a surface (41) of the through hole (21, 22) of the second member (19) that is oriented away from the body (35) of the second member (19) to form the pretensioned connection between the first member (18) and the second member (19); 2. The assembly of claim 1, wherein in the expanded state of the connector (24), a pretensioned connection is established between the first member (18) and the second member (19), and the through hole (20) of the first member (18) is positioned offset relative to the through holes (21, 22) of the second member (19).

3. The connector (24) a compressed state in which the connector (24) has a size that allows it to be freely inserted and removed from the channel (23); a connected state, in which the connector (24) is expanded inside the channel (23) to connect the first member (18) and the second member (19) to each other; and 3. The assembly according to claim 1 or 2, comprising:

4. The connector (24) At least one extension block (25); at least one wedge (26) having an inclined surface (28) facing said at least one expansion block (25); an actuator (27) configured to displace at least one of the wedges (26) relative to the expansion block; Equipped with The connector (24) At least one wedge (26) disposed between two of the expansion blocks (25); Two wedges (26) that are disposed between the two expansion blocks (25), or that are disposed symmetrically and inclined away from each other, or that are disposed between the two expansion blocks (25) and that are disposed symmetrically and inclined away from each other, The assembly according to any one of claims 1 to 3, comprising at least one of:

5. 5. The assembly of claim 4, wherein the actuator (27) is a bolt that engages in a threaded recess in the wedge (26).

6. 6. An assembly according to claim 4 or 5, wherein the inclined surface (28) of the wedge (26) is inclined at an angle of less than 15°, preferably less than 10°, more preferably less than 8°, and most preferably less than or equal to 6°, relative to the displacement direction of the wedge (26).

7. 7. An assembly according to any one of claims 4 to 6, wherein the expansion block (25) has a surface in at least partial contact with the wedge (26) having an orientation that coincides with the inclined surface (28) of the wedge (26).

8. The first member (18) and the second member (19) are overlapping tubular members, 8. An assembly as claimed in any one of the preceding claims, wherein the through holes (20, 21, 22) are radially aligned with respect to the tubular member so as to form the radially extending channel (23).

9. The assembly of any one of claims 1 to 8, wherein a plurality of the channels (23) and a plurality of the connectors (24) are arranged along the circumference of the first member (18) and the second member (19).

10. the first member (18) and the second member (19) are members of an offshore structure, preferably an offshore wind turbine structure (1); each of the first member (18) and the second member (19) being an upright member of a monopile (3); or 10. The assembly according to any one of claims 1 to 9, wherein the first member (18) and the second member (19) are members (1) of an offshore structure, preferably an offshore wind turbine structure, and each of the first member (18) and the second member (19) are upright members of a monopile (3).

11. one of the first member (18) and the second member (19) is a rotor blade (6) of a wind turbine; An assembly according to any one of the preceding claims, wherein the other of the first member (18) and the second member (19) is arranged on a hub.

12. An assembly according to any one of the preceding claims, wherein said second member (19) comprises an assembly of said body (35) and two substantially parallel said walls (36).

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