Coupling assembly and method for driving a single pile

Abstract

A coupling assembly and a method of driving a monopile. The present invention relates to a coupling assembly (1) for connecting a tower (32) or a transition piece of a wind turbine (30) to a monopile (31), the coupling assembly comprising a first coupling member (2) configured to be connected to the monopile (31) and a second coupling member (3) configured to be connected to the first coupling member (2). The present invention also relates to a tower end of a tower (32) of a wind turbine (30), the tower end being connected to the second coupling member (3) of the coupling assembly (1). Finally, the present invention also relates to a method of driving a monopile (31) of a wind turbine (30) into the ground, the top end of the monopile (31) being connected to the first coupling member (2) of the coupling assembly (1).

Description

Field of the Invention

[0001] The present invention relates to a coupling assembly for connecting a tower or a transition piece of a wind turbine to a monopile. The present invention also relates to a tower end of a wind turbine tower connected to the coupling assembly. Finally, the present invention also relates to a method of driving a monopile of a wind turbine into the ground. Background Art

[0002] Wind turbines are increasingly being used to generate electrical energy. A wind turbine typically includes a tower and a nacelle mounted on the tower, with a hub attached to the nacelle. A rotor is mounted at the hub and coupled to a generator. A plurality of blades extend from the rotor. The blades are oriented in such a way that the wind passing over the blades rotates the rotor and causes the shaft to rotate, thereby driving the generator to generate electricity.

[0003] The tower of a wind turbine typically includes a plurality of tower segments to facilitate transportation of the tower from the production site to the installation site. These segments are typically joined together by flanges fastened with fasteners. The strength of the flange connection depends on various parameters, such as the choice of steel, wall thickness, bolt diameter, number of bolts in the bolt circle, load path, etc. Flanges having a T-shape (i.e., so-called T-flanges) have proven to be able to resist higher loads compared to other flanges such as L-flanges (i.e., flanges having an L-shape). The use of T-flanges and L-flanges for connecting tower segments of a wind turbine is known from US 2013 / 0180199A1.

[0004] Thus, in order to increase the strength of the flange connection between tower segments, one approach could be to use a T-flange, which has an inverted "T" shape, where the inner flange extends into the tower and the outer flange extends outwards from the tower. A T-flange can have a strength that is approximately twice that of an L-flange, i.e., it can withstand a load that is approximately twice the load that a comparable L-flange can withstand. However, the main drawback of a T-flange is that it requires access from both outside and inside the tower. Although a T-flange has a greater load-bearing capacity than an L-flange, the assembly and lifetime maintenance of a wind turbine with a tower having a T-flange result in significant additional costs. However, the underside of a T-flange is that it has bolts on the outside of the tower shell, so it is highly exposed to the corrosive environment of an offshore wind farm. Access to a T-flange for maintenance purposes is also difficult.

[0005] Furthermore, the current development of wind turbines tends towards taller towers, as well as towers with smaller diameters and longer rotor blades, which results in higher loads in the tower than can be supported by an L-flange. Due to the increased height and weight of the new generation of wind turbines, an L-flange may not be suitable for supporting the loads of some new generation wind turbines. Due to the drawbacks of this type of flange, the use of a T-flange is also not optimal.

[0006] Another type of flange that can support higher loads than an L-flange is the X-flange. Thus, the X-flange is suitable for supporting the loads of a new generation of wind turbines. A first concept of an X-flange connection is described in NL1004960C1. The concept of the X-flange is to have inclined studs that cross at a point aligned with the median plane of the circumference of the tower shell. This feature gives the flange great strength while keeping the studs accessible on the inside of the tower.

[0007] XL-flanges are also flanges that can support the loads of a new generation of wind turbines. Their shape results from a combination of an X-flange and an L-flange, i.e., a flange with an X-shaped orifice and an L-orifice circle at its inner radius. Thus, the XL-flange is a special variant of the X-flange, where the L-component serves as an interface for the attachment of equipment among other purposes. The XL-flange is easier to handle and transport than the X-flange due to the L-component of the flange.

[0008] An important criterion for establishing a highly competitive offshore wind farm is to reduce the installation costs of offshore wind turbines. The offshore wind turbine tower is installed on a foundation to anchor the offshore wind turbine to the seabed. Usually, the foundation consists of a monopile, which is advantageous because the same heavy lifting equipment of a vessel can be used to drive a large monopile into the ground and to install the wind turbine tower on the monopile. Usually, vessels are chartered, so minimizing the usage time of the vessels can greatly reduce the total cost of production and installation of offshore wind turbines.

[0009] A method of driving a monopile to the required penetration depth at an offshore location of a turbine is to use a driving unit, such as a hammer, usually a hydraulic hammer. The bottom section of the monopile needs to be driven deep into the soil to be able to withstand the overturning moment during the lifetime of the wind turbine. For this purpose, an anvil connected to the hammer is positioned above the top end of the monopile. The base of the anvil distributes the impact of the hammer blow evenly over the top surface of the monopile. In this specification, a "blow" is defined as transferring the load from the hammer to the anvil. During the blow, the hammer may be lifted due to the pressure of the hydraulic fluid supplied to the hammer by the power unit. When the fluid is removed, the hammer descends and creates a downward stroke on the anvil.

[0010] In certain offshore installations, monopiles are provided with transition pieces for connecting a tower to the monopile. The transition piece can be connected to the monopile by a grouted connection. In a grouted connection, grout is injected into a grout chamber which is defined when the transition piece is lowered onto the monopile and the walls of the transition piece and the monopile overlap, the monopile having been previously driven into the seabed. It can take several weeks until the grout hardens, thus making the grouting process very expensive. This hardening also strongly depends on weather conditions, which can lead to long delays in the installation process. Thus, due to the increased operating time of the vessels used for the installation of offshore wind turbines, the grouted connection is very costly. Additionally, due to the large overlap of steel sections and the required grout material, the material costs increase.

[0011] The use of flanges to connect tower sections can be extended to the connection of monopiles to other functional components. For example, a flange can be used to connect a tower to a monopile or to connect a transition piece to a monopile. This is highly advantageous as no grouted connection is required, which saves costs.

[0012] It is known to use an L-flange connected to a monopile to drive the monopile into the ground. For this purpose, a first L-flange is connected to the monopile, while a second L-flange is connected to the tower. The first L-flange is coupled to the top surface of the monopile and has a flange portion that extends radially inwards at the top of the flange, the flange portion having holes for fastening the first L-flange to the second L-flange. The radial extension should be understood as an extension in the radial direction of the axis of the wind turbine. To protect the socket of the L-flange from the impact of the driving unit, the contact area where the driving unit impacts the flange is flat, and the socket is provided at a tapered area at the inner radial extension of the flange. This ensures a clearly defined contact area and thus the transfer of force is concentrated within a controlled area.

[0013] At the flange connected to the monopile, the contact area for the anvil impact of the driving unit is defined to ensure that the structure is not damaged when driving the monopile into the soil. This is achieved by impacting the part of the flange surface that is aligned with the tower shell and the monopile shell (i.e., the outer radius of the flange). Thus, the flange portion that extends radially inwards where there is a socket for connecting the flange to a complementary flange is not affected by the impact of the driving unit, and damage to the socket does not occur. When the driving unit impacts the contact area, the force is transferred vertically from the driving unit through the flange portion aligned with the monopile shell to the monopile.

[0014] For newly developed heavier offshore wind turbines, due to the above reasons, the L-flange connection cannot support the high loads of the turbine. The solution to this problem is to use flanges that can support higher loads, such as X-flanges and XL-flanges. However, the X-flanges and XL-flanges known in the prior art have the orifices of the sockets in the area where they are aligned with the tower shell and the monopile shell (i.e., in the area where the drive unit impacts the flange), and if the drive unit impacts the socket, this results in damage to the socket. Therefore, it is not possible to drive the monopile into the ground using X-flanges and XL-flanges without further modifying these flanges, because the methods known in the prior art for hammering L-flanges are not applicable to hammering X-flanges and XL-flanges without previously modifying this type of flange to make it suitable for being hammered. Hammering this area will damage the orifice and prevent the insertion of studs or other fasteners into the socket and proper fastening. Summary of the Invention

[0015] Accordingly, it is an object of the present invention to provide an improved flange resistant to the impact of the drive unit, which is also capable of supporting the high loads of a new generation of wind turbines.

[0016] This is achieved by a coupling assembly according to claim 1, a tower end of a tower of a wind turbine connected to the coupling assembly according to claim 14, and a method of driving a monopile of a wind turbine into the ground according to claim 15.

[0017] A coupling assembly for connecting a tower or a transition piece of a wind turbine to a monopile according to the present invention includes a first coupling member configured to be connected to the monopile and a second coupling member configured to be connected to the first coupling member. The first coupling member includes a first annular connection surface and an inclined first socket configured to be inserted by a fastener. The second coupling member has a second annular connection surface configured to abut the first annular connection surface of the first coupling member. The second coupling member further includes an inclined second socket configured to be inserted by a fastener.

[0018] The first coupling member can be configured as a flange adapted to be connected to a complementary flange, which is the second coupling member. The flange of the first coupling member has a first annular connection surface that will abut the second annular connection surface of the complementary flange.

[0019] According to the present invention, the first annular connection surface includes a contact area and a load transfer area. The contact area is the area of the first annular connection surface in which, during the installation of the monopile, the drive unit impacts the first coupling member to drive the monopile into the ground. The load transfer area is the area of the first annular connection surface in which the load is transferred from the second coupling member to the first coupling member. The contact area is a different area of the first annular connection surface from the load transfer area.

[0020] The advantage of having a contact area that is different from the load transfer area is that the driving unit has a clearly defined area in which the driving unit impacts the flange to drive the monopile into the ground.

[0021] Since the first socket opening may be damaged by the driving unit, complicating the fastening of the first coupling member to the second coupling member, it is necessary to avoid the impact of the driving unit on any first socket opening. Advantageously, the contact area is at a distance from any socket opening.

[0022] According to a preferred embodiment of the present invention, the first socket of the first coupling member is located at the load transfer area of the first annular connection surface. This is advantageous because the driving unit only impacts the contact area, which is an area different from the load transfer area. Therefore, the first socket is not damaged by the driving unit.

[0023] According to another preferred embodiment of the present invention, the first annular connection surface has a main circle with an annular arrangement of inclined openings of the first sockets forming a socket circle and a secondary circle with an annular arrangement of inclined openings of the first sockets forming another socket circle, the main circle and the secondary circle being at different radii from the axis of the wind turbine. Advantageously, the first sockets of the main circle and the first sockets of the secondary circle are alternately distributed to form the X-orifice feature of the X flange and the XL flange.

[0024] The inclined openings of the first coupling member extend from the first annular connection surface into the body of the first coupling member. Similarly, the inclined openings of the second coupling member extend from the second annular connection surface into the body of the second coupling member. The advantage of the inclined sockets is that the engagement is effectively completed within the main part of the coupling assembly. This means that the load is transferred more effectively through the coupling assembly. In contrast, the connection of a conventional L flange is at the inner radial extension of the flange, which is away from the main part of the flange aligned with the tower shell or the monopile shell, causing the load path to deviate and resulting in a greater bending moment.

[0025] According to a preferred embodiment, the first sockets of the main circle and the secondary circle are an alternation of blind holes and through holes. The blind holes terminate in the body of the first coupling member. The through holes extend all the way through the body of the first coupling member. In other words, every other opening in the main circle and the secondary circle is an inclined through hole, and the other openings are inclined blind holes.

[0026] Similarly, the second socket of the second coupling member corresponding to the first socket of the first coupling member is also an alternation of blind holes and through holes, such that the fastener is introduced through the through hole of the first coupling member and the blind hole of the second coupling member, and vice versa. In other words, the blind hole of the first coupling member is aligned with the through hole of the second coupling member, and the through hole of the first coupling member is aligned with the blind hole of the second coupling member. This allows for the formation of the X orifice feature of the X flange and the XL flange.

[0027] According to a preferred embodiment of the present invention, the first annular connection surface has at least two load transfer regions, and the contact region is radially positioned between the two load transfer regions. In the radial case, it means the radial direction from the axis of the wind turbine or from the axis of the monopile, and the axis of the wind turbine and the axis of the monopile are the same axis. This is advantageous because the bending moment caused by having a single load transfer region can be avoided, since the two load transfer regions distribute the load transfer over the surface of the first annular connection surface. Since one load transfer region is in the outer radial region of the first annular connection surface and the other load transfer region is in the inner radial region of the first annular connection surface, the load can be optimally distributed from the second coupling member to the first coupling member.

[0028] According to a preferred embodiment of the present invention, the major circle of the first socket is at the outer radial load transfer region, and the minor circle of the first socket is at the inner radial load transfer region. This allows for the optimal distribution of the load and protects the first socket from the driving unit.

[0029] According to another preferred embodiment of the present invention, the first coupling member and / or the second coupling member is formed by a plurality of components.

[0030] The advantage of dividing the coupling assembly into different components or into components with different heights is that the connection surface between the first coupling member and the second coupling member can be selected to have a defined contact region away from the opening of the first socket of the first coupling member. In contrast, if the coupling assembly has a one-piece first coupling member and a one-piece second coupling member with the same height, the separation of the two coupling members will be in the middle of the coupling assembly, and due to the X-shaped arrangement of the sockets, the contact region will exactly fall on the opening of the first socket, which should be avoided so as not to damage the first socket when driving the monopile into the ground.

[0031] According to another preferred embodiment of the present invention, the contact area is aligned with the connection area where the first coupling member is connected to the monopile. Thus, the driving unit impacts the area aligned with the monopile shell, and the load is transmitted vertically to drive the monopile into the ground. This avoids having bending moments at the flange and at the monopile when driving the monopile into the ground. In addition, the impact force of the driving unit can be directly and vertically transmitted to the fillet of the flange neck and to the monopile, thus avoiding vibrations and tilts that may cause damage to the first coupling member.

[0032] According to another preferred embodiment of the present invention, the contact area is not configured to support the load of the wind turbine. The contact area is also not configured to support the preloading of the fasteners of the coupling assembly. For this purpose, the load transfer area can be configured to support the load of the wind turbine and / or support the preload of the fasteners of the coupling assembly.

[0033] The impact of the driving unit on the contact area results in a steep uneven surface and deformation of the contact area after driving the monopile. Since it cannot be foreseen how the contact area will look after driving, the complementary surface of the second coupling member will not optimally abut the contact area, resulting in poor load transfer after driving the monopile. Therefore, a specific area configured for contact with the driving unit and a different specific area configured for load transfer of the wind turbine can solve this problem.

[0034] According to a preferred embodiment of the present invention, the first annular connection surface has a bulge at the contact area configured to be impacted by the driving unit. This allows for a clearly defined contact area where the driving unit is positioned and impacts the first coupling member to drive the monopile. In addition, the body of the first coupling member is not affected by the impact of the driving unit because the deformation of the contact surface occurs at the bulge. Thus, the body of the first coupling member is protected from the impact of the driving unit.

[0035] According to another preferred embodiment of the present invention, the first annular connection surface has an inclined surface to protect the first socket from being damaged by the driving unit. For this purpose, the driving unit impacts the flat surface of the first annular connection surface at the corner between the inclined surface and the flat surface, and the first socket is not affected by the deformation. In addition, the inclined surface enables the contact area to be defined at the flat surface of the first annular connection surface aligned with the monopile shell and with the fillet of the flange neck of the first coupling member, such that the impact of the driving unit on the flat surface of the first annular connection surface is vertically transmitted to the monopile through the body of the first coupling member at the fillet of the flange neck. This results in a clearly defined straight load path. The inclination angle should be large enough such that the inclined surface does not contact the driving unit during driving of the monopile.

[0036] The use of a raised or inclined surface also facilitates more efficient energy transfer of the drive unit impact and poses a lower risk of damaging the flange of the first coupling member. In the absence of these features, the impact force of the drive unit can cause excessive vibration and tilting, which may lead to damage to the first coupling member, especially around the fillet of the flange neck.

[0037] According to another preferred embodiment of the present invention, the inclined surface is positioned radially inward from the contact area. This is particularly advantageous if the first coupling member has a main circle of the inclined opening of the first socket at the flat area of the first annular connection surface and a secondary circle of the inclined opening of the first socket at the inclined area of the first annular connection surface. If the anvil of the drive unit has an outer diameter smaller than the diameter of the main circle, the main circle is not affected by the impact of the drive unit. In addition, since the secondary circle is provided at the inclined surface of the first annular connection surface, the secondary circle is also protected from impact.

[0038] According to another preferred embodiment of the present invention, the inclined surface is a load transfer area configured to support the load of the wind turbine and / or the preload of the fastener of the coupling assembly. In addition, if the parts of the inclined surface and the flat surface that are not the contact area are also load transfer areas, bending moments can be avoided because the two load transfer areas distribute the load transfer on the surface of the first annular connection surface, and the load can be optimally distributed from the second coupling member to the first coupling member.

[0039] The area of the inclined surface near the corner between the inclined surface and the flat surface of the first annular connection surface may also be partially damaged due to the impact of the drive unit on the flat surface at the corner. Therefore, the area of the inclined surface near the corner may not be suitable as a load transfer area configured to support the load of the wind turbine and / or the preload of the fastener of the coupling assembly. However, the remaining part of the inclined surface, and in particular the part of the inclined surface that includes the first socket not near the corner between the inclined surface and the flat surface of the first annular connection surface, can be a load transfer area configured to support the load of the wind turbine and / or the preload of the fastener of the coupling assembly.

[0040] According to another preferred embodiment of the present invention, the second coupling member further includes a recess aligned with the contact area. This recess allows the first coupling member to be coupled to the second coupling member without having to press the raised portion of the first coupling member against the second coupling member.

[0041] According to another preferred embodiment of the present invention, there is a gap between the first coupling member and the second coupling member in the contact area. Advantageously, when the first coupling member and the second coupling member are coupled together, there is a gap between the protrusion of the first coupling member and the recess of the second coupling member. The impact of the drive unit on the contact area results in an uneven surface and deformation, such as sharp corners or peaks in the contact area or protrusions on the contact area. Due to this sharp uneven surface of the contact area after driving the single pile, the contact area is subsequently unsuitable for supporting the load of the wind turbine and / or the preloading of the fasteners of the coupling assembly. By having a tolerance wide enough to form a gap between the protrusion of the first coupling member and the recess of the second coupling member, contact between the contact area and the second annular connection surface can be avoided, thereby avoiding damage to the second annular connection surface caused by deforming the surface against the contact area.

[0042] The gap between the two components is not an essential feature, and there may be contact between the contact area and the second annular connection surface. However, the contact area is not suitable for supporting and transmitting the load of the wind turbine. To transmit the load, the first annular connection surface has a region different from the contact area, and this contact area is the load transmission region.

[0043] According to another preferred embodiment of the present invention, the second coupling member further includes a chamber configured to protect the second socket. The chamber can be drilled in some parts of the region where the fastener is fastened to the second coupling member to protect the second socket. The advantage of using it is that there is enough space between the contact area and the second coupling member to avoid any damage to the second coupling member. Additionally, the fastener can be inserted and fastened more easily.

[0044] According to another preferred embodiment of the present invention, the transition piece is connected to the second coupling member of the coupling assembly. The second coupling member has a second annular connection surface configured to abut against the first annular connection surface of the first coupling member of the coupling assembly, and the second coupling member further includes an inclined second socket configured for the insertion of a fastener.

[0045] According to another preferred embodiment of the present invention, the tower end of the tower is connected to the transition piece. The transition piece is connected to the second coupling member of the coupling assembly. The second coupling member has a second annular connection surface configured to abut against the first annular connection surface of the first coupling member of the coupling assembly, and the second coupling member further includes an inclined second socket configured to be inserted by a fastener.

[0046] Another aspect of the present invention relates to a tower end of a wind turbine tower connected to a second coupling member of a coupling assembly, the second coupling member having a second annular connection surface configured to abut against a first annular connection surface of a first coupling member of the coupling assembly, and the second coupling member further including an inclined second socket configured to be inserted by a fastener.

[0047] Another aspect of the present invention relates to a method of driving a monopile of a wind turbine into the ground, the top end of the monopile being connected to the first coupling member of the coupling assembly, the method comprising the steps of: positioning the driving unit on a contact area of the first coupling member, and causing the driving unit to impact the contact area of the first coupling member to drive the monopile into the ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] For the purpose of facilitating an understanding of the features of the present invention and as part of this specification, some drawings of an illustrative and non - limiting nature are attached, on which the following are shown:

[0049] Figure 1 A perspective view of an offshore wind turbine is shown.

[0050] Figure 2 A view showing driving a monopile into the ground using a driving unit and a first coupling member according to an embodiment of the present invention is shown.

[0051] Figure 3 A view showing driving a monopile into the ground using a driving unit and a first coupling member according to an embodiment of the present invention is shown.

[0052] Figures 4 to 8 Coupling assemblies according to different embodiments of the present invention are shown.

[0053] Figure 9 Shown Figure 8 An enlarged view IX of the contact area of the shown coupling assembly.

[0054] Figure 10 Shown Figure 8 A perspective view of the first coupling member of the shown coupling assembly.

[0055] Figure 11 Shown Figure 8 A perspective view of the second coupling member of the shown coupling assembly.

[0056] Figure 12 Coupling assemblies according to another embodiment of the present invention are shown.

[0057] Figure 13 Shown Figure 12 The enlarged Figure XIII.

[0058] Figure 14 Shows the driving of a monopile into the ground using a driving unit and a first coupling member according to another embodiment of the present invention.

[0059] Figures 15 to 18 Shows a coupling assembly according to another different embodiment of the present invention.

[0060] Figures 19 to 22 Shows a coupling assembly according to another embodiment of the present invention.

[0061] Figure 23 Shows Figures 19 to 22 a perspective view of the second coupling member of the coupling assembly of Detailed Description

[0062] Figure 1 Shows a perspective view of a wind turbine 30 installed in an offshore wind farm. The wind turbine 15 includes a hub connected to a generator (not shown) disposed within a nacelle 33. The hub includes three wind turbine blades 34. The nacelle 33 is disposed at the upper end of a tower 32 of the wind turbine 30. The tower 32 includes a plurality of tower sections. The tower 32 is directly mounted on a foundation, which in this case is a monopile 31.

[0063] Figure 2 and Figure 3 Shows a cross-sectional view of a first coupling member 2 of a coupling assembly 1 attached to a monopile 31 (not shown) during the installation of the wind turbine 30 in an offshore wind farm, the monopile being driven into the ground by a driving unit 20.

[0064] The driving unit 20 includes a hammer 21 and an anvil 22. The first coupling member 2 has a contact area 10 where the anvil 22 contacts the first coupling member 2 and transmits the force from the driving unit 20 through the first coupling member 2 to the monopile 31 to drive the monopile 31 into the ground. For this purpose, the anvil 22 is positioned above the monopile 31 on the top surface of the first coupling member 2 that forms a first annular connection surface 4, which is subsequently used to couple a second coupling member 3 to the first coupling member 2 of the coupling assembly 1. The base of the anvil 22 distributes the impact of the hammer 21 strike evenly over the contact area 10 of the first annular connection surface 4.

[0065] Any impact of the anvil 22 on the opening of any one of the first sockets 6 is to be avoided, because the opening of the first socket 6 may be damaged by the drive unit 20, which complicates the fastening of the first coupling member 2 to the second coupling member 3 by means of the fastener 9. To achieve this, the contact area 10 is at a sufficiently wide distance from the opening of any one of the first sockets 6. Additionally, the force from the drive unit 20 should be transmitted vertically to ensure that the structure is not damaged when driving the single pile 31 into the soil. Therefore, the contact area 10 is aligned with the single pile 31 shell, and the force is transmitted directly and perpendicularly to the single pile 31 from the contact area 10 to the fillet of the flange neck of the first coupling member 2 to drive the single pile 31 into the ground.

[0066] The defined contact area 10 remote from the opening of the first socket 6 can be achieved by forming an anvil bulge at the area of the anvil 22 that contacts the contact area 10, as Figure 2 shown. Thus, the anvil 22 is directly placed on the contact area 10 by the anvil bulge and transmits the load of the hammer 21 only at the contact area 10. By the anvil bulge, contact between the anvil 22 and the first socket 6 is avoided.

[0067] Alternatively, the defined contact area 10 remote from the opening of the first socket 6 can be achieved by forming a bulge 12 at the first coupling member 2, as Figure 3 shown. Here, the flat anvil 22 contacts the first coupling member 2 only at the bulge 12 of the first annular connection surface 4, thus avoiding contact of the anvil 22 at the opening of the first socket 6.

[0068] Figures 4 to 8 The coupling assembly 1 according to different embodiments of the present invention is shown. In these figures, the first coupling member 2 is formed by a single part, while the second coupling member 3 is formed by one or more parts, depending on the embodiment of the present invention. The second coupling member 3 formed by multiple parts is advantageous for the manufacturing process because individual parts can be produced more easily.

[0069] Dividing the coupling assembly 1 into different parts or into parts with different heights has the further advantage that the connection surfaces of the first coupling member 2 and the second coupling member 3 can be selected to have a defined contact area 10 remote from the opening of the first socket 6 of the first coupling member 2. If the coupling assembly 1 shown in these figures has a one-piece first coupling member 2 and a one-piece second coupling member 3 with the same height, the separation of the two coupling members 2, 3 will be in the middle of the coupling assembly 1, and the contact area 10 will precisely fall on the opening of the first socket 6, which should be avoided so as not to damage the first socket 6 when driving the single pile 31 into the ground.

[0070] Thus, by dividing the second coupling member 3 into different components or by selecting different heights of the first coupling member 2 and the second coupling member 3, Figures 4 to 8 each embodiment of the invention shown in

[0071] In Figure 4 and Figure 5 has a contact area 10 remote from the opening of the first socket 6.

[0072] In Figure 6 and Figure 7 the coupling assembly 1 is divided into three unequal components, two of which form the second coupling member 3 and one of which forms the first coupling member 2. For example, in Figure 7 the second coupling member 3 is formed by an upper flange member and an intermediate ring.

[0073] In Figure 8 the coupling assembly 1 is divided into four unequal components, three of which form the second connecting member 3 and one of which forms the first connecting member 2. The second connecting member 3 is composed of two annular members with similar shapes and an upper flange member with a shape similar to that of the first connecting member 2 but without the bulge 12, because this member is not touched by the drive unit 20. By having similar components, the production cost is lower. For example, two identical rings can be manufactured for the intermediate annular member of the second coupling member 3, and then one of the rings can be drilled along the surface to obtain the recess 13 of the second coupling member 3.

[0074] Figure 9Shows an enlarged view of region IX where the second annular connection surface 5 of the second coupling member 3 abuts the first annular connection surface 4 of the first coupling member 2, in particular a view of the contact region 10 and its surroundings. As can be seen here, at the contact region 10, there is a small gap between the protrusion 12 of the first coupling member 2 and the recess 13 of the second coupling member 3. It is advantageous to have a tolerance between the two coupling members 2, 3 in the contact region 10 because during the driving of the monopile 31 into the ground, when the driving unit 20 impacts on the protrusion 12 of the first coupling member 2, the protrusion 12 of the first coupling member 2 will be partially deformed. Such an impact on the protrusion 12 results in a deformation of the contact region 10 on the protrusion 12 such as steep corners or spikes. Due to such a steep uneven surface of the contact region 10 after the driving of the monopile 31, the contact region 10 is not suitable for supporting the load of the wind turbine 30 and / or for supporting the preloading of the fastener 9 of the coupling assembly 1. By having a sufficiently wide tolerance to form a gap between the protrusion 12 of the first coupling member 2 and the recess of the second coupling member 3, contact between the contact region 10 and the second annular connection surface 5 can be avoided, thus avoiding damage to the second annular connection surface 5 due to pressing the second annular connection surface 5 against the deformed contact region 10.

[0075] A gap between the two components is not an essential feature, and there may be contact between the contact region 10 and the second annular connection surface 5. However, the contact region 10 is not suitable for supporting and transmitting the load of the wind turbine 30. To transmit the load, the first annular connection surface 4 has a region different from the contact region 10, which is the load transfer region 11.

[0076] In Figure 8 In the cross-sectional view, the load transfer region 11 is located on the side of the contact region 10. The load transfer region 11 is a region different from the contact region 10. Once the coupling assembly 1 is coupled, the load of the wind turbine 30 is transferred from the second coupling member 3 to the first coupling member 2 through the load transfer region 11 of the first annular connection surface 4.

[0077] Figure 10 Shows Figure 8 A perspective view of the first coupling member 2 of the coupling assembly 1. The protrusion 12 forming the contact region 10 is a region different from the load transfer region 11. Thus, when driving the monopile 31 into the ground, the driving unit 20 only contacts the protrusion 12 at the contact region 10 of the first annular connection surface 4. The protrusion 12 is spaced apart from each first socket 6 of each socket circle 8 to avoid damage to the first socket 6 when the driving unit 20 impacts the contact region 10.

[0078] Figure 11 Shows Figure 8Perspective view of the second coupling member 3 of the coupling assembly 1 in []. The second annular connection surface 5 of the second coupling member 3 is configured to abut the first annular connection surface 4 of the first coupling member 2 at the load transfer region 11 of the first annular connection surface 4. The second socket 7 of the second coupling member 3 corresponds to the first socket 6 of the first coupling member 2.

[0079] As can be seen in the figure, the first socket 6 and the second socket 7 are inclined sockets 6, 7, i.e., sockets 6, 7 with inclined openings. The inclined openings extend from the annular connection surfaces 4, 5 into the bodies of the coupling members 2, 3.

[0080] The holes and openings at the L-member of the coupling assembly 1 are for connection to an intermediate structure, rather than for fastening the second coupling member 3 to the first coupling member 2. The intermediate structure is a device such as a holding structure used during transportation of the coupling members 2, 3 or a lifting interface used during installation, which does not necessarily need to be an element of the tower 32 or the coupling assembly 1.

[0081] Figure 12 and Figure 13 Shows a coupling assembly 1 according to another embodiment of the present invention. In this case, there is no gap between the contact region 10 of the first coupling member 2 and the second annular connection surface 5 of the second coupling member 3. Figure 13 Particularly shows Figure 12 an enlarged view of region XIII of

[0082] To avoid damage to the first socket 6, the first annular connection surface 4 has an inclined surface 15 in the region radially inward from the contact region 10. The inclination angle θ should be sufficient such that the inclined surface 15 does not contact the driving unit 20 during driving of the monopile 31, as Figure 14 shown in []. The anvil 22 has an outer diameter smaller than the diameter of the outer first socket 6. Thus, the outer first socket 6 of the first coupling member 2 is protected against impact from the driving unit 20. The inner first sockets 6 of the first coupling member 2 are also protected because they are at the inclined surface 15 that does not contact the driving unit 20.

[0083] The load of the wind turbine 30 is transferred by the load transfer region 11 at the outer part of the first annular connection surface 4 (i.e., the part radially outward from the contact region 10) and by the load transfer region 11 at the inclined surface 15 at the inner part of the first annular connection surface 4. For this purpose, the second coupling member 3 also has an inclined surface 15 that matches the inclined surface 15 of the first coupling member.

[0084] Figures 15 to 18 Shows a coupling assembly 1 according to another different embodiment of the present invention. In Figure 15 [], to Figure 12The embodiment of Figure 16 adds a recess 13 to avoid deformation of the contact area 10 caused by the drive unit 20 from damaging the second annular connection surface 5 of the second coupling member 3. In Figure 15 a protrusion 12 is added to the first coupling member 2 as shown in the embodiment of Figure 17 to have a clearly defined contact area 10 where the drive unit 20 impacts the first coupling member 2. In Figure 18 the first coupling member 2 does not have a protrusion 12 and thus has a flat surface of the first annular connection surface 4, and the second coupling member 3 has a recess 13. Figure 8 The X flange with the contact area 10 is shown, and the contact area is similar to that of the XL flange of Figure 8 and Figure 18 The only difference between Figure 18 is that Figure 8 does not have the L part of the XL flange of

[0085] Figures 19 to 23 Fig. shows a coupling assembly 1 according to another embodiment of the present invention. In these figures, the coupling assembly 1 is divided into four unequal parts, three of which form the second coupling member 3 and one of which forms the first coupling member 2. The second coupling member 3 is formed by two annular parts with similar shapes and an upper flange part with a shape similar to that of the first coupling member 2 but without a protrusion 12, because this part is not impacted by the drive unit 20.

[0086] Therefore, as seen in other embodiments of the present invention, the first coupling member 2 has a protrusion 12 at the contact area 10. Similarly, the second coupling member 3 has a recess 13. Additionally, each ring of the second coupling member 3 has a chamber 14 in the area where the fastener 9 passes through the coupling assembly 1. These chambers 14 can be drilled in a rectangular shape as shown in the figure or in an oval shape, depending on the size of the drill bit.

[0087] The advantage of using the chamber 14 in addition to the recess 13 is that there is sufficient space between the contact area 10 and the second coupling member 3 to avoid any damage to the second coupling member 3. Additionally, the fastener 9 can be inserted and fastened more easily.

[0088] The use of the chamber 14 can also be extended to embodiments with an inclined surface 15.

[0089] List of reference numerals

[0090] 1 Coupling assembly

[0091] 2 First coupling member

[0092] 3 Second coupling member

[0093] 4 First annular connection surface

[0094] 5 Second annular connection surface

[0095] 6 First jack

[0096] 7 Second jack

[0097] 8 Jack circle

[0098] 9 Fastener

[0099] 10 Contact area

[0100] 11 Load transfer area

[0101] 12 Protrusion

[0102] 13 Recess

[0103] 14 Chamber

[0104] 15 Tapered surface

[0105] 20 Driving unit

[0106] 21 Hammer

[0107] 22 Anvil

[0108] 30 Wind turbine

[0109] 31 Monopile

[0110] 32 Tower

[0111] 33 Nacelle

[0112] 34 Blade

[0113] θ Tapered angle.

Claims

1. A coupling assembly (1) for connecting a tower (32) or a transition piece of a wind turbine (30) to a monopile (31), the coupling assembly comprising a first coupling member (2) configured to be connected to the monopile (31) and a second coupling member (3) configured to be connected to the first coupling member (2). The first connecting member (2) includes a first annular connection surface (4) and an inclined first insertion hole (6) configured to be inserted by a fastener (9), wherein, The first annular connection surface has a main circle with an annular arrangement of inclined openings including first sockets forming a socket circle and a secondary circle with an annular arrangement of inclined openings including first sockets forming another socket circle, the main circle and the secondary circle being at different radii from the axis of the wind turbine, wherein the first sockets of the main circle and the secondary circle are alternating blind holes and through holes; and The second coupling member (3) has a second annular connection surface (5) configured to abut the first annular connection surface (4) of the first coupling member (2), wherein the second coupling member (3) further includes an inclined second socket (7) configured to be inserted by the fastener (9), wherein the second sockets of the second coupling member corresponding to the first sockets of the first coupling member are also alternating blind holes and through holes. Characterized in that the first annular connection surface (4) includes a contact area (10) and a load transfer area (11), the contact area (10) being that area of the first annular connection surface (4) which is located between the main circle and the secondary circle and is aligned with the shell of the monopile and is configured to be struck by a driving unit (20) during installation of the monopile (31) to drive the monopile (31) into the ground, the load transfer area (11) being the area of the first annular connection surface (4) configured to transfer the load from the second coupling member (3) to the first coupling member (2), wherein the contact area (10) is a different area of the first annular connection surface (4) from the load transfer area (11); wherein the first coupling member (2) and the second coupling member (3) have different heights extending along the axis of the wind turbine, and wherein the second coupling member (3) further includes a recess (13) aligned with the contact area (10), and the second coupling member (3) further includes a chamber (14) configured to protect the second socket (7).

2. The coupling assembly (1) according to claim 1, characterized in that, The first annular connection surface (4) has at least two load transfer areas (11), and the contact area (10) is radially positioned between the two load transfer areas (11).

3. The coupling assembly (1) according to claim 1 or 2, characterized in that, The first coupling member (2) and / or the second coupling member (3) is formed by a plurality of components.

4. The coupling assembly (1) according to claim 1 or 2, characterized in that, The contact area (10) is aligned with the connection area where the first coupling member (2) is connected to the monopile (31).

5. The coupling assembly (1) according to claim 1 or 2, characterized in that, The contact area (10) is not configured to support the load of the wind turbine (30).

6. The coupling assembly (1) according to claim 1 or 2, characterized in that, The load transfer area (11) is configured to support the load of the wind turbine (30).

7. The coupling assembly (1) according to claim 1 or 2, characterized in that, The first annular connection surface (4) has a bulge (12) at the contact area (10) configured to be struck by the driving unit (20).

8. The coupling assembly (1) according to claim 1 or 2, characterized in that, The first annular connection surface (4) has an inclined surface (15) to protect the first socket (6) from being damaged by the drive unit (20).

9. The coupling assembly (1) according to claim 8, characterized in that, The inclined surface (15) is positioned radially inwards from the contact area (10).

10. The coupling assembly (1) according to claim 8, characterized in that, The inclined surface (15) is a load transfer area (11) configured to support the load of the wind turbine (30).

11. The coupling assembly (1) according to claim 1 or 2, characterized in that, When the second coupling member (3) is connected to the first coupling member (2), there is a gap between the first coupling member (2) and the second coupling member (3) at the contact area (10).

12. A tower end of a tower (32) of a wind turbine (30), the tower end being connected to the second coupling member (3) of the coupling assembly (1) according to any one of claims 1 to 11.

13. A method of driving a monopile (31) of a wind turbine (30) into the ground, the top end of the monopile (31) being connected to the first coupling member (2) of the coupling assembly (1) according to any one of claims 1 to 11, the method comprising the steps of: - positioning the drive unit (20) on the contact area (10) of the first coupling member (2), and - causing the drive unit (20) to impact on the contact area (10) of the first coupling member (2) to drive the monopile (31) into the ground.

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