Method for connecting a blade to a hub and method for disconnecting a blade from a hub

Abstract

A method for connecting a blade (5) to a hub (6) of a wind turbine (1), the method comprising pulling (S5) the blade (5) towards the hub (6) using a rope (15) guided through the interior (22) of the hub (6). Thus, during the connection process, movements between the hub (6) and the blade (5), in particular movements caused by vibrations or fluctuations, are reduced.

Description

[0001] The present invention relates to a method for connecting a blade to a hub of a wind turbine. Furthermore, the present invention relates to a method for disconnecting a blade from a hub of a wind turbine. Background Art

[0002] A wind turbine generally includes a tower, a nacelle mounted to the tower, a hub rotatably mounted to the nacelle, and rotor blades mounted to the hub.

[0003] Modern wind turbine rotor blades are made of fiber reinforced plastic. The rotor blades usually include an airfoil with a rounded leading edge and a sharp trailing edge. The rotor blades are connected to the hub of the wind turbine via their blade roots. Furthermore, the rotor blades are connected to the hub by means of pitch bearings that allow the pitch movement of the rotor blades.

[0004] In many cases, the rotor blades are transported to the erection site of the wind turbine in order to lift and mount the rotor blades to the hub once the hub has been mounted to the nacelle at the top of the tower. The connection of the blades to the hub is therefore usually made at an elevated height. This usually requires that the crane lifting the blades does not move substantially relative to the hub. Therefore, when such blades are connected offshore, a jack-up vessel must usually be provided which provides a rigid connection to the seabed. Summary of the invention

[0005] It is an object of the present invention to provide an improved method for connecting and disconnecting a blade to a hub.

[0006] Therefore, a method for connecting a blade to a hub of a wind turbine is provided. The method comprises pulling the blade towards the hub using a rope guided through the interior of the hub.

[0007] Thus, during the connection process, movements between the hub and the blade, in particular movements due to vibrations or waves, can be reduced. This has the advantage that the blade can be mounted to the hub offshore by means of a vessel floating in the water. Thus, for example, the provision of a jack-up vessel can be avoided.

[0008] "Rope" refers to a long element which is configured to transmit tensile forces and cannot transmit compressive forces / thrust forces. In particular, the rope is a tensioning cable, a cable, a belt, a chain and / or a cable. In particular, tension is maintained in the rope. Preferably, the rope is pulled from the interior of the hub, in particular by means of a winch or the like. "Guided through the interior of the hub" means that at least a part of the rope is located inside the hub.

[0009] A "wind turbine" currently refers to a device that converts the kinetic energy of wind into rotational energy, which can be converted back into electrical energy by the device.

[0010] According to an embodiment, the method comprises the following steps: a) providing a hub mounted to a tower of a wind turbine, b) providing a blade and a rope, the rope being connected to the blade by one end thereof, c) lifting the blade towards the hub, d) placing the other end of the rope inside the hub, e) pulling the rope at the other end, and f) connecting the blade to the hub.

[0011] Preferably, the rope is connected to the blade root by one of its ends. In particular, in step c), the blade is lifted to the height of the hub. For example, steps a)-f) are performed in the order listed. The hub is preferably mounted to the nacelle and the nacelle is mounted to the tower.

[0012] According to another embodiment, the hub comprises a blade connection interface having a hole leading to the interior of the hub, wherein the rope is placed into the hole in step d).

[0013] This has the advantage that the blade can be pulled directly towards the blade connection interface by means of the rope.Preferably, the hole is a hatch of the hub.

[0014] According to another embodiment, the blade is pulled towards the hub in the longitudinal direction of the blade.

[0015] This has the advantage that the blade is moved in the connection direction so that the connection means, such as a pin or a bolt, can engage in a corresponding opening when the blade is moved in the same direction of movement. Preferably, the blade is pulled in a horizontal direction. "Longitudinal direction" means the direction pointing from the blade tip to the radial center of the blade root.

[0016] According to a further embodiment, the movement of the blade perpendicular to the longitudinal direction of the blade is limited by means of a first guide element.

[0017] This has the advantage that the blade can be kept sufficiently close to the hub during the blade connection process even when extensive disturbance factors occur due to wind, waves etc. "Perpendicular to the longitudinal direction" refers to the radial and / or transverse direction.

[0018] According to another embodiment, the first guiding element limits the movement perpendicular to the longitudinal direction of the blade by engaging in the blade or in the hub when the blade moves towards the hub (first guiding step).

[0019] This has the advantage that a reliable limitation of radial movement may be provided.The first guide element may be connected to one of the blade root and the hub.The other of the blade root and the hub comprises a receptacle for receiving the first guide element.

[0020] According to another embodiment, the first guide element is a guide cage which is connected to the hub and protrudes from the hub, in particular from the blade connection surface (20).

[0021] Preferably, the guide cage is connected to the hub by means of a spring element. This has the advantage that, due to the elasticity of the spring element, damage of the blade can be avoided when the blade hits the first guide element. For example, the spring element can be made of spring steel. The guide cage can be a grid structure.

[0022] According to a further embodiment, the first guide element has a conical shape.

[0023] This has the advantage that fitting the first guide element into the corresponding receptacle is facilitated since the conical shape serves as an insertion ramp.

[0024] According to another embodiment, the second guide element limits the movement perpendicular to the longitudinal direction of the blade by engaging in the first guide element when the blade moves towards the hub (second guiding step).

[0025] This has the advantage that the movement of the blade relative to the hub can be further limited. Preferably, the second guide element engages into the first guide element when the blade is closer to the hub than in the first guiding step. In particular, the second guide element is fixed to the blade root within a cavity in the blade root.

[0026] According to another embodiment, the second guide element comprises a tube connected to the blade, wherein the first guide element comprises a receptacle for receiving the tube.

[0027] This has the advantage that a further mechanical guide is provided which is robust and reliable. Preferably, the receptacle is an inverted cone. Preferably, the tube protrudes in the longitudinal direction of the blade. In particular, the rope can extend through the tube. The tube can also be referred to as a duct. The tube or duct can be formed of a rigid material such as, for example, steel.

[0028] According to a further embodiment, the receptacle comprises an insertion chamfer for centering the second guide element.

[0029] In particular, the insertion bevel guides the second guide member into the inverted tapered insertion hole. This has the advantage that the pipe can be smoothly guided into the insertion hole.

[0030] According to a further embodiment, a movement of the blade relative to the hub perpendicular to the longitudinal direction of the blade is limited to less than 150 mm, 100 mm or 80 mm by means of the second guide element.

[0031] This has the advantage that the gap between the blade and the hub can be kept small enough so that the connection step between the blade and the hub can be formed. "Limited to less than 150 mm" may mean that the maximum movement distance from one stop to the opposite stop is less than 150 mm.

[0032] According to another embodiment, in step f), a plurality of pins protruding from the blade root engage in corresponding holes provided in the hub.

[0033] When the pin passes through the hole, for example, the guiding step is completed and a radial movement of the blade relative to the hub is not possible. Thus, a tight form-fit connection between the blade and the hub is provided. The pin is, for example, part of a bolt connection or a bolt. Preferably, the blade and the hub are screwed together.

[0034] According to another embodiment, the rope is connected to the blade, in particular to the blade root, inside a cavity in the blade.

[0035] Preferably, the cavity is open and thus accessible. This means that the first guide element passes through the cavity and that the cavity receives the first guide element when the blade moves towards the hub.

[0036] According to another embodiment, the blade is held by means of a vessel floating in the water.

[0037] This has the advantage that the blade connection process can be performed without a jack-up vessel and, therefore, cost-effectively and / or in offshore areas with great water depths.

[0038] Furthermore, a blade for a wind turbine is provided, the blade comprising a blade root and a rope, which is connected to the blade root by one end thereof, such that the blade root can be pulled by means of the free end of the rope.

[0039] All embodiments and features explained with reference to this method apply mutatis mutandis to the blade of the invention.

[0040] Furthermore, a method for disconnecting a blade from a hub of a wind turbine is provided. The method comprises pulling the blade away from the hub, wherein a rope guided through the interior of the hub maintains tension between the hub and the blade.

[0041] All embodiments and features explained with reference to the method for connecting a blade to a hub apply mutatis mutandis to the method for disconnecting a blade from a hub of the present invention.

[0042] Other possible implementations or alternative solutions of the present invention also include combinations of features described above or below with respect to the embodiments (not explicitly mentioned herein). Those skilled in the art may also add separate or independent aspects and features to the most basic form of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further embodiments, features and advantages of the present invention will become apparent from the subsequent description and the dependent claims in conjunction with the accompanying drawings, in which:

[0044] Figure 1 shows a perspective view of a wind turbine according to one embodiment;

[0045] Figure 2 Shown according to Figure 1 a perspective view of a wind turbine blade of a wind turbine;

[0046] Figure 3 shows a schematic side view of a blade and a hub before the blade and the hub are connected together;

[0047] Figure 4 A schematic longitudinal section through a blade is shown;

[0048] Figures 5 to 7 Different positions of the blades when directed towards the hub are shown;

[0049] Figure 8 shows a schematic front view of a guide element;

[0050] Fig. 9 A block diagram showing a method for connecting a blade to a hub; and

[0051] Fig.10 A block diagram of a method for disconnecting a blade from a hub is shown. DETAILED DESCRIPTION

[0052] In the drawings, like reference numbers indicate identical or functionally equivalent elements unless otherwise indicated.

[0053] Figure 1 A wind turbine 1 is shown. The wind turbine 1 comprises a rotor 2 connected to a generator (not shown) arranged within a nacelle 3. The nacelle 3 is arranged at an upper end of a tower 4 of the wind turbine 1 .

[0054] The rotor 2 comprises three blades 5 (i.e. wind turbine blades). The blades 5 are connected to a hub 6 of the wind turbine 1. A rotor 2 of this type may have a diameter ranging, for example, from 30 to 300 meters or even more. The blades 5 are subject to high wind loads. At the same time, the blades 5 need to be lightweight. For these reasons, the blades 5 in modern wind turbines 1 are made of fiber-reinforced composite materials, for example by means of casting. Typically, glass or carbon fibers in the form of unidirectional fiber mats are used. Such blades 5 may also include wood and other reinforcing materials.

[0055] Figure 2 Shows Figure 1The blade 5 comprises an aerodynamically designed portion 7, which is shaped to optimally utilize wind energy, and a blade root 8 for connecting the blade 5 to the hub 6. Furthermore, the blade 5 comprises a blade tip 9 facing away from the blade root 8. The blade 5 extends in a longitudinal direction L, which is directed from the blade tip 9 to the blade root 8. The wind turbine blade 5 comprises a leading edge 10 and a trailing edge 11.

[0056] Figure 3 A schematic side view of a blade 5 and a hub 6 before being connected to each other is shown. The blade 5 is lifted by means of a crane 12 arranged on a vessel 13. The blade 5 is lifted to the same height H as the hub 6 so as to connect the blade 5 and the hub 6 together. The blade root 8 comprises an open cavity 14 (see dotted lines) or an open hollow space. A rope 15 is connected to the blade 5 in the cavity 14 with one end 16 thereof so that the blade root 8 can be pulled by means of a free end 17 of the rope 15. A weight 18 can be arranged at the free end 17. The rope 15 can be arranged as a tensioning cable. Preferably, an auxiliary rope 19 is provided to keep the rope 15 in a central position in the cavity 14.

[0057] The hub 6 comprises a blade connection interface 20 for connecting the blade root 8 thereto. Preferably, the hub 6 comprises two further blade connection interfaces (not shown). The blade connection interface 20 comprises a hole 21, in particular a hatch, leading to an interior 22 of the hub 6. Furthermore, a guide element 23 (also referred to as a first guide element) is connected to the blade connection interface 20.

[0058] The guide element 23 is configured to enter and engage the cavity 14. This means that when the blade 5 moves towards the hub 6, the cavity 14 receives the guide element 23. When doing so, the movement of the blade 5 perpendicular to the longitudinal direction L (i.e. in the radial direction R) relative to the hub 6 is limited. The cavity 14 acts as a receptacle for receiving the guide element 23, thereby forming a form fit in the radial direction R. This has the advantage that a reliable limitation of radial movement can be provided.

[0059] In order to provide a movement of the blade 5 relative to the hub 6 in the longitudinal direction L, the free end 17 of the rope 15 is placed through the hole 21 into the interior 22 so that the rope 15 is guided through the interior 22 of the hub 6. The guide element 23 is, for example, a guide cage connected to the hub 6 and protruding from the hub 6. The guide element 23 is connected to the hub 6, for example, by means of a spring element 24. This has the advantage that, due to the elasticity of the spring element 24, damage to the blade 5 can be avoided when the blade 5 hits the guide element 23. The guide element 23 can be a grid structure.

[0060] Preferably, the guide element 23 has a tapered shape. In particular, the guide element 23 widens towards the blade connection interface 20. This has the advantage that fitting the cavity 14 onto the guide element 23 is facilitated, since the tapered shape serves as an insertion ramp.

[0061] Figure 4 A schematic longitudinal section through a blade 5 is shown. A guide element 25 (also called second guide element) is connected to the blade 5 within the cavity 14. Preferably, the guide element 25 extends in the longitudinal direction L. In particular, the guide element 25 is a rod and / or a probe. The guide element 25 can have a centered alignment within the cavity 14.

[0062] The guide element 25 may comprise a hollow element 26, in particular a tube, and a hollow element 27, in particular a tube, slidably supporting the hollow element 26. The sliding movement may be limited by a stopper 28 arranged in the hollow element 27. For example, the rope 15 may extend through the hollow element 26 and the hollow element 27 and may be fixed to the blade 5 or the hollow element 27 via a connection point 29, in particular an anchor point. The hollow element 27 is connected to the blade root 8 in the cavity 14.

[0063] The rope 25 may extend from the guide element 25 through a ring 30 which is connected to the rope 19 and held in a central position in the cavity 14. The rope 19 is guided through a rotating element 31, in particular a guide roller, and connected to the blade 5 via a connection point 32, in particular an anchor point. The rope 19 may be an elastic cable.

[0064] Figures 5 to 7 Different positions of the blade 5 are shown when being guided towards the hub 6. The free end 17 of the rope 15 is guided through the interior 22 of the hub 6. A force F pulls at the free end 17 so that the blade root 8 moves towards the blade connection interface 20 of the hub 6. The pulling force F can be provided, for example, by means of a winch (not shown).

[0065] Furthermore, a plurality of pins 33, in particular bolts, protruding from the blade root 8 in the longitudinal direction L are configured to engage in corresponding holes 34 provided in the hub 6, in particular in the blade connection interface 20. The guide element 25 is configured to limit the movement of the blade 5 in the radial direction R by engaging in the guide element 23, in particular in a receptacle 35 in the guide element 23, when the blade 5 moves towards the hub 6. This has the advantage of providing a robust and reliable additional mechanical guidance. Preferably, the receptacle 35 is an inverted cone that tapers towards the hub 6.

[0066] like Figure 5 As shown, the guide element 23 does not engage in the cavity 14. When the distance D between the blade connection interface 20 and the blade root 8 is further reduced, as shown in FIG. Figure 6As shown in FIG. 1 , the guide element 23 engages in the cavity 14 and limits the relative movement of the blade root 8 in the radial direction R. When the distance D is further reduced, the guide element 25 is captured by the seat 35, as shown in FIG. Figure 7 The receptacle 35 comprises an insertion chamfer 36 for capturing and centering the guide element 25. This has the advantage that the movement of the blade root 8 relative to the hub 6 can be further limited.

[0067] For example, when the guide element 25 is engaged in the receptacle 35 (eg Figure 7 ), the movement of the blade 5 relative to the hub 6 in the radial direction R is limited to less than 150 mm, 100 mm or 80 mm. This has the advantage that the gap between the blade 5 and the hub 6 can be kept small enough so that the pin 33 can engage in the hole 34.

[0068] When the pin 33 passes through the hole 34, for example, the guiding step is completed and a radial movement of the blade 5 relative to the hub 6 is impossible. Thus, a tight form-fit connection between the blade 5 and the hub 6 is provided. The pin 33 is, for example, part of a bolt connection or a bolt. Preferably, the blade 5 and the hub 6 are screwed together, in particular by means of a bolt and a nut (not shown) connected to the bolt.

[0069] Figure 8 A schematic front view of a guide element 23 is shown. The guide element 23 comprises a circular base portion 37 (e.g. a ring), a receptacle 35, and in particular five guide portions 38 arranged in a circle and connecting the receptacle 35 to the base portion 37. The receptacle 35 comprises a central opening 39 (also referred to as an insertion hole) for being passed through by the guide element 25 and for guiding the rope 15. The receptacle 35 has an opening portion 40, so that the opening 39 is radially accessible.

[0070] Fig. 9 A block diagram of a method for connecting a blade 5 to a hub 6 is shown. In step S1, a hub 6 mounted to a tower 4 of a wind turbine 1 is provided. In step S2, a blade 5 and a rope 15 connected to the blade 5 with one end 16 thereof are provided, in particular by means of a vessel 13. In step S3, the blade 5 is lifted towards the hub 6, in particular by means of a crane 12.

[0071] In step S4, the other end 17 of the rope 15 is placed in the interior 22 of the hub 6. In step S5, the blade 5 is pulled toward the hub 6 using the rope 15 guided through the interior 22. In step S6, the guide element 23 is passed through the cavity 14 (first guiding step), so that the radial movement of the blade root 8 is limited by means of the first gap. In step S7, the guide element 25 is passed through the guide element 23 (second guiding step), so that the radial movement of the blade root 8 is limited by a second gap that is smaller than the first gap.

[0072] Thus, the hub 6 and the blade 5 are sufficiently close together by means of a two-stage physical guiding system. In step S8, the pin 33 passes through the hole 34. In step S9, the blade 5 and the hub 6 are connected by fixing them to each other. Step S5 may be repeated during steps S6 to S8. Steps S1 to S9 (e.g., except step S5) are preferably performed in the order listed.

[0073] Fig.10 A block diagram of a method for disconnecting a blade 5 from a hub 6 is shown. The method comprises a step S11 of releasing the connection means 33 between the blade 5 and the hub 6. In a step S12, the blade 5 is pulled away from the hub 5, in particular by means of a crane 12, wherein a rope 15 guided through the interior 22 of the hub 6 maintains tension between the hub 6 and the blade 5. This has the advantage that the blade 5 cannot slip off the hub 6. Furthermore, the guide elements 23, 25 serve as a limitation of the movement in the radial direction R.

[0074] Although the present invention has been described in terms of preferred embodiments, it will be apparent to those skilled in the art that modifications are possible in all embodiments. Figures 1 to 9 All characteristics described apply mutatis mutandis to Fig.10 The method shown in for disconnecting the blade 5 from the hub 6 and vice versa.

Claims

1. A method for connecting a blade (5) to a hub (6) of a wind turbine (1), the method comprising: The blade (5) is pulled (S5) towards the hub (6) using a rope (15) guided through the interior (22) of the hub (6), wherein the method further comprises the steps of: a) providing (S1) the hub (6) mounted to the tower (4) of the wind turbine (1), b) providing (S2) the blade (5) and the rope (15), the rope being connected to the blade (5) with one of its ends (16), c) lifting (S3) the blade (5) towards the hub (6), d) placing (S4) the other end (17) of the rope (15) into the interior (22) of the hub (6), e) pulling (S5) the rope (15) at the other end (17), and f) connecting (S9) the blade (5) to the hub (6), wherein the blade (5) is pulled towards the hub (6) in the longitudinal direction (L) of the blade (5), and the movement of the blade (5) perpendicular to the longitudinal direction (L) of the blade (5) is limited by means of a first guide element (23); and wherein, when the blade (5) moves towards the hub (6), the second guide element (25) limits the movement perpendicular to the longitudinal direction (L) of the blade (5) by engaging in the first guide element (23); and wherein the second guide element (25) comprises a tube (26) connected to the blade (5), and wherein the first guide element (23) comprises a receptacle (35) for receiving the tube (26).

2. The method according to claim 1, wherein: The hub (6) comprises a blade connection interface (20) having a hole (21) leading to an interior (22) of the hub (6), and wherein, in step d), the rope (15) is placed into the hole (21).

3. The method according to claim 1 or 2, wherein: in, The first guide element (23) is a guide cage which is connected to the hub (6) by means of a spring element and protrudes from the hub (6).

4. The method according to claim 3, wherein: The guide cage has a grid structure.

5. The method according to claim 3, wherein: The first guide element (23) is connected to the hub (6) and protrudes from a blade connection surface.

6. The method according to claim 1 or 5, wherein: The first guide element (23) has a conical shape.

7. The method according to claim 1, wherein: The receptacle (35) comprises an insertion chamfer (36) for centering the second guide element (25).

8. The method according to claim 1 or 7, wherein: By means of the second guide element (25), the movement of the blade (5) relative to the hub (6) perpendicular to the longitudinal direction (L) of the blade (5) is limited to less than 150 mm, 100 mm or 80 mm.

9. The method according to claim 1 or 2, wherein: In step f), a plurality of pins (33) protruding from the blade root (8) engage (S8) in corresponding holes (34) provided in said hub (6).

10. The method according to claim 1 or 2, wherein: The rope (15) is connected to the blade (5) within a cavity (14) in the blade (5).

11. A method for disconnecting a blade (5) from a hub (6) of a wind turbine (1), the method comprising: pulling the blade (5) away from the hub (6), wherein a rope (15) guided through the interior (22) of the hub (6) maintains tension between the hub (6) and the blade (5), wherein when the blade is disconnected from the hub along the longitudinal direction of the blade, the movement of the blade perpendicular to the longitudinal direction is limited by a first guide element, wherein, when the blade (5) moves towards the hub (6), the second guide element (25) limits the movement perpendicular to the longitudinal direction (L) of the blade (5) by engaging in the first guide element (23); and wherein the second guide element (25) comprises a tube (26) connected to the blade (5), and wherein the first guide element (23) comprises a receptacle (35) for receiving the tube (26).

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