SEGMENTED ROTOR BLADE FOR WIND TURBINES

Description

[0001] The present invention relates to a segmented rotor blade for wind turbines having at least two blade segments extending in opposite directions from a joint in a longitudinal direction, wherein each blade segment has at least one inner spar element forming a structural element of the rotor blade.

[0002] With the increasing expansion of renewable energies, the question of the efficiency of such renewable energy-based energy systems is increasingly coming into focus. Especially in the field of wind turbines, also known as wind energy plants, it has been shown that the larger the rotor blades, the more energy can be generated, making the use of such wind turbines more profitable.

[0003] However, as rotor blades become longer, the problem arises that transport to the installation site becomes increasingly expensive and sometimes even impossible. Beyond a certain length, rotor blades can no longer be easily transported via public infrastructure. One solution to this transport problem is segmented rotor blades, in which the rotor blade is divided into two or more segments. These segments are then transported separately and joined together at the installation site.

[0004] Segmented rotor blades require a connection technology at their joint. Insert screw connections are often used to connect the individual rotor blade segments to each other in a force-fitting and form-fitting manner.

[0005] WO 2010 / 023299 A2 discloses a segmented rotor blade that is assembled at its spars. For this purpose, the spar section of one segment extends beyond the joint into the second segment, with the spars being secured to each other by means of a screw connection. Among other things, the screw connection forces the spars together to achieve the highest possible stability and rigidity.

[0006] A particular disadvantage here is the fact that the components required for the screw connection must be manufactured with great precision, as otherwise, stresses within the components can lead to failure of the screw connection. However, such a tolerance level is not always available, especially in the area of ​​rotor blades made of fiber-reinforced plastics.

[0007] EP 2 288 807 B1 also discloses a segmented rotor blade in which the spar section of one of the segments also extends beyond the joint into the other segment. The two segments are bolted to the end faces of the spars by means of the spars, thus achieving a force-locking connection at the joint.

[0008] DE 31 09 566 C2 discloses a rotor blade for wind turbines and clamping devices for assembly, wherein two rotor blade segments are held together by means of an expansion screw.

[0009] DE 10 2008 055 513 A1 discloses a rotor blade for wind turbines which also consists of several segments, with the individual segments being joined together by means of an adhesive.

[0010] From WO 2009 / 090537 A2 and WO 2011 / 067323 A2, a segmented rotor blade is known in which a connecting element extends into the other blade segment and is fastened there by means of a screw connection.

[0011] WO 2016 / 087594 A1 discloses a segmented rotor blade for wind turbines, wherein the blade segments each comprise at least one spar element, which are pushed into each other to connect them. A cross bolt passing through both spar elements secures the connection, with the cross bolt being mounted in a sliding bushing contained in the respective openings of the spar elements.

[0012] Further prior art is disclosed in US 2006 / 083611.

[0013] A major problem when connecting segmented rotor blades using a screw connection with nested spars is the fact that the bushings of the two spar sections involved in the screw connection must be positioned with high precision to ensure they are exactly axially aligned. Only in this way is a play-free connection between the two rotor blade segments possible, which can withstand the stresses and strains of a wind turbine in continuous operation. In practice, the openings required in the spars are produced in a single step when the spars are inserted together. This means that the individual segments have to be assembled at least once during rotor blade production in order to create the bushing holes. However, this has several disadvantages. Firstly, a lot of space is required in the production hall, which has a negative impact on the investment costs.Furthermore, an additional processing step is required, which takes time and reduces productivity. Finally, the technology known from practice has the disadvantage that only the two wing segments drilled together fit together, which means that the individual segments cannot be manufactured in series, but only in pairs. A variable interchange of the segments is therefore no longer possible.

[0014] Furthermore, the load-bearing capacity of the insert screw connection is too low for modern, slim, and very long rotor blades. On the one hand, the pull-out force of the insert from the laminate limits the load-bearing capacity, and on the other, the strength of the connecting longitudinal bolt is limited. Blade segmentation can only be successful if the segmentation position is shifted far toward the blade tip (to approximately 80% of the blade length). However, a segmentation in the middle of the blade is significantly more advantageous from a transport perspective, as the maximum component length is minimized. In addition, an enlarged profile at the segmentation position is often necessary to generate more space for the connecting elements and increase the section modulus against bending. An enlarged profile leads to aerodynamic losses, which impairs the economic efficiency of the entire wind turbine.

[0015] It is therefore an object of the present invention to provide an improved rotor blade which can be segmented in a meaningful way for transport and at the same time has a high connection quality.

[0016] The object is achieved according to the invention with the segmented rotor blade according to claim 1. Advantageous embodiments of the invention can then be found in the corresponding subclaims.

[0017] According to claim 1, a segmented rotor blade for wind turbines is proposed, comprising at least two blade segments extending in opposite directions from a joint in a longitudinal direction, wherein each blade segment has at least one inner spar element forming a structural element of the rotor blade, wherein a) the first spar element of the first blade segment and the second spar element of the second blade segment are joined together at the joint by their end faces by means of a connecting arrangement, b) wherein the connecting arrangement has a plurality of connecting assemblies, each of which connects the spar elements to one another, c) wherein each connecting assembly comprises a first cross-bolt, a second cross-bolt, and at least one connecting link, which has a first link opening and a second link opening at its ends, d) wherein in each connecting assembly, the first cross-bolt is guided transversely to the longitudinal direction of the rotor blade through a spar opening in the first spar element and the first link opening of the connecting link, and the second cross-bolt is guided transversely to the longitudinal direction of the rotor blade through a spar opening in the second spar element and the second link opening of the connecting link,so that the connecting plate connects the spar elements to one another, and e) wherein at least the first cross bolt of a first connecting assembly and the second cross bolt of a second connecting assembly opposite the first connecting assembly are connected to one another via at least one first shear connecting element.

[0018] Accordingly, the two spar elements of the blade segments are joined at their ends and then assembled using a plurality of connecting assemblies, so that the spar elements do not have to be pushed into one another. Instead, the spar elements are joined at their ends and then connected to one another in a force-fitting and form-fitting manner using the connecting assemblies, whereby the spar elements do not necessarily have to touch at their ends. In particular, the spar elements are not pushed into one another to create a connection between the blade segments.

[0019] Each spar element has a spar opening for the corresponding connecting assembly, through which a cross bolt is inserted. The cross bolt serves to connect the connecting plate to the respective spar element. To do this, the cross bolt is inserted through one of the plate openings of the connecting plate, so that the cross bolt is guided through both the connecting plate and the spar opening of the spar element. A second cross bolt is then guided through the spar opening of the other spar element and through the opposite plate opening of the connecting plate, so that the spar elements are connected to each other using the two cross bolts and the connecting plate.

[0020] Since there are several connecting sets, the beam elements can be firmly connected to one another.

[0021] According to the invention, it is further provided that the first cross bolt of a first connecting assembly and the second cross bolt of a second connecting assembly are connected to one another via at least one first shear connection element, so that shear forces can be transmitted via the connection point. The connection of the shear connection elements, for example in the form of a push rod, to the cross bolts is particularly advantageous because the cross bolts, due to their solid construction, enable a high connection strength and thus eliminate the need for additional connection points on the blade segments. This reduces mass and complexity.

[0022] The shear connection element connects a first cross bolt, which is arranged in a spar opening of the first spar element, with a second cross bolt, which is arranged in a spar opening of the second spar element. This allows the shear forces to be safely transmitted and dissipated via the connection arrangement, making the connection arrangement significantly more stable.

[0023] In this case, the connecting assemblies, whose first and second transverse bolts are connected to one another via the shear connecting element, are arranged opposite one another in the connecting arrangement, so that the shear connecting element runs from a first side of the spar elements to an opposite second side of the spar elements, for example from a front side to a rear side of the rotor blade.

[0024] In contrast to the state of the art, longitudinal bolting is omitted, but instead a connection is made via transverse bolts, as these generally offer greater joint strength. This allows the mass and complexity of the segmented rotor blade to be reduced.

[0025] The rotor blade can be made of a fiber composite material comprising a fiber material and a matrix material embedding the fiber material. In particular, the spar elements of the rotor blade can be made of such a fiber composite material. Suitable fiber materials include, for example, GRP or CFRP. However, it is also conceivable to use a fiber-metal laminate (FML) material, in which layers of fiber material and layers of metal material alternate, thus achieving a particularly high bond strength. The use of fiber-metal laminates is particularly advantageous in the area of ​​the spar openings in order to achieve a particularly high hole bearing strength and create a secure connection.

[0026] The material of the connecting plates can be metal (steel, e.g., 1.7225). Metallic connecting plates can be manufactured cost-effectively from sheet metal (preferably 10 to 100 mm thick), for example, by plasma cutting, water jet cutting, laser cutting, wire EDM, or punching. Alternatively, the connecting plates can also be forged in variable, load-adapted thicknesses.

[0027] As an alternative to metallic materials, the connecting plates can also be made of FML (fiber-metal laminate), similar to the FML used in the connection area. This can reduce the weight of the connection technology. Alternatively, the connecting plates can be made of a pure fiber-reinforced plastic composite to further reduce weight. Using fiber-reinforced 3D printing or fiber placement, the fibers can be optimally aligned in the load direction, particularly in the radial and tangential directions at the plate openings.

[0028] At least two connecting plates can be provided per connecting assembly to increase the strength of the connecting assembly. The first connecting plate is arranged on a first side surface of the beam opening at a first end of the cross bolt, while the second connecting plate is arranged on a second side surface of the beam opening opposite the first side surface at a second end of the cross bolt. The sections of the beam elements to be connected are located between the two connecting plates.

[0029] According to one embodiment, it is provided that the second cross bolt of the first connecting set and the first cross bolt of the second connecting set are connected to one another via a second shear connection element.

[0030] This creates a type of cross shear connection in order to achieve optimal transfer of the shear forces.

[0031] According to one embodiment, it is provided that the first spar element and the second spar element each have a first belt element and an opposite second belt element, both of which are connected to one another by at least one intermediate web element, wherein the transverse bolts are inserted into spar openings of the belt elements transversely to the longitudinal direction of the rotor blade.

[0032] The chord elements are elongated, flat, and / or ribbon-shaped elements that, together with the intermediate web element, form the spar element. In cross-section, such a spar element with chord elements and web element has a profiled shape, for example, in the form of a U-profile or a double-T profile. It is also conceivable, however, for the spar elements to have a closed cross-section, thus forming a tubular shape, for example. The two chord elements are connected at their two elongated sides via the web elements.

[0033] Preferably, the at least one web element has a recess in the area of ​​the connecting arrangement, not only to save weight on the spar elements but also to enable improved accessibility to the connecting arrangement. This is particularly advantageous when the web element runs centrally across the width of the belt elements.

[0034] According to one embodiment, it is provided that the first connecting set connects the first belt element of the first spar element to the first belt element of the second spar element and the second connecting set connects the second belt element of the first spar element to the second belt element of the second spar element.

[0035] Since the belt elements are usually arranged opposite one another and the web element extends between them, the first connecting assembly and the second connecting assembly are also arranged opposite one another so that the first and, if necessary, the second shear connecting element can be arranged between them.

[0036] It is conceivable that such a pair of first and second connecting assemblies is provided on both the left and right sides of the belt elements, with the web element then running between these pairs of connecting assemblies. Preferably, the web element is recessed in the area of ​​the connecting arrangement to ensure accessibility to the elements of the connecting arrangement.

[0037] According to one embodiment, the connecting tabs have at their two ends a head section with the tab openings, which are connected to one another via a connecting section, wherein the width of the connecting section is tapered in the middle.

[0038] This enables further weight savings, especially when a large number of these connecting plates are used in the connection arrangement. For example, it is conceivable that a total of four connecting assemblies are used to connect two spar elements, with each connecting assembly comprising two connecting plates. Two connecting assemblies can be provided for the first belt elements, while the other two connecting assemblies are provided for the second belt elements.

[0039] According to one embodiment, it is provided that a bushing with a conical inner wall is introduced into at least one spar opening of the spar elements, which bushing interacts with a transverse bolt with a conical outer wall in the inserted state in such a way that a radial clamping force is applied to the inner wall of the spar opening.

[0040] By using such a clamping bush, the cross bolt is positioned in the beam opening without any play, thus achieving the best possible force transmission. The clamping bush can be provided with a flange to ensure contact with the outside edge of the beam openings.

[0041] Furthermore, it can be provided that the clamping bush and / or the cross bolt are eccentric in order to be able to adjust the relative distance between the first cross bolt in the first beam element and the second cross bolt in the second beam element.

[0042] According to one embodiment, it is provided that the cross bolt has a conical outer wall in the region of the tab opening, so that a cavity is created between an inner wall of the tab opening and the conical outer wall of the cross bolt, into which a conical expansion sleeve is inserted, which is pressed into the cavity by means of a pressure cover arranged on an end face of the cross bolt.

[0043] This makes it possible for the connection of the cross bolt and the respective connecting plate to be positively connected and without play, so that the best possible power transmission is also achieved.

[0044] The object is also achieved according to the invention with the wind turbine according to claim 8, wherein the wind turbine has a multi-blade rotor which has at least one rotor blade according to one of the preceding claims.

[0045] The invention is explained in more detail by way of example with reference to the accompanying figures. They show: Figure 1: Top view of the connecting arrangement according to the invention; Figure 2: Side view of the connecting arrangement; Figure 3: Side view of the connecting arrangement with cover; Figures 4a, 4b: Illustration of the connecting arrangement with clamping bush; Figures 5a, 5b: Illustration of the connecting arrangement with additional expansion sleeve; Figure 6: Schematic representation of the assembly of the connecting bolt of a tool.

[0046] The same reference numerals in the figures also designate the same elements in the other figures.

[0047] Figure 1shows the connecting arrangement 100 according to the invention in a plan view of the connecting plates 7, each of which is part of a connecting assembly and with which a first chord element 1 of a first spar element is to be connected to a second chord element 2 of a second spar element. The first chord element 1 of the first spar element is the root-side segment, while the second chord element 2 of the second spar element represents the tip-side segment. The connecting arrangement 100 according to the invention thus connects the spar elements of the segmented rotor blade.

[0048] Figure 2 and 3 show a detailed side view of this connection arrangement 100. The entire spar of the rotor blade accordingly comprises a first spar element with the two belt elements 1 and 3 and the web element 5 arranged therebetween, and a second spar element with the two belt elements 2 and 4 and the web element 6 arranged therebetween.

[0049] The flange elements 1, 2, 3, and 4 can have a greater thickness or width in the connection area than in the rest of the rotor blade to increase the load-bearing capacity of the connection. However, compared to conventional connection techniques based, for example, on metallic inserts, significantly less or no increase in the cross-section of the flanges is necessary, as the connection strength is extremely high. The flanges are preferably reinforced with metal layers in the connection area, creating a fiber-metal laminate (FML) with high hole bearing strength.

[0050] The blade segments are connected to the cross bolts 9 with connecting plates 7 and 8. These can be Figure 1shown, are designed with a tapered shape in order to save weight and material costs. The material of the connecting plates 7, 8 is preferably a metal, e.g. steel (e.g. 1.7225). Metallic connecting plates can be produced cost-effectively from heavy plate (thickness preferably 10 to 100mm), for example by plasma cutting, water jet cutting, laser cutting, wire erosion or punching. Alternatively, the connecting plates can also be forged in variable, load-appropriate thicknesses. As an alternative to the metallic materials, the connecting plates are made from an FML similar to the FML that is used in the connection area of ​​the belts. This can reduce the weight of the connection technology. Alternatively, the connecting plates are made from a pure fiber-plastic composite in order to save weight even further.By means of fiber-reinforced 3D printing or fiber placement, the fibers can be optimally aligned in the load direction, particularly in the radial and tangential directions at the tab openings through which the cross bolts 9 are guided.

[0051] The connecting plates 7 and 8 connect the two blade segments to the cross bolts 9 with maximum strength and minimum weight.

[0052] The web elements 5, 6 of the blade segments are interrupted at the connection point to allow access to the connection technology, so that no thrust can be transmitted here. To transmit the thrust across the connection point, shear connection elements 20, e.g., in the form of push rods, are used. These are connected to the cross bolts 9. The connection of the shear connection elements 20 to the cross bolts 9 is particularly advantageous because, due to their solid construction, these connection elements enable a high connection strength, thus eliminating the need for additional connection points on the blade segments. This reduces mass and complexity.

[0053] The belt elements 1 and 2 as well as 3 and 4 are connected to the connecting plates 7 and 8 via the cross bolts 9. Preferably, two connecting sets are used for each belt, each consisting of two cross bolts 9 and an outer connecting plate 7 and an inner connecting plate 8.

[0054] In the example of Figure 1 , 2 and 3 the belt elements 1 and 2 are connected with two connecting sets, each connecting set having two connecting plates 7a and 8a in order to connect the belt elements 1 and 2 to each other by means of the cross bolts 9.

[0055] The cross bolt of chord element 1 is connected to the cross bolt of chord element 4 via a shear connection element 20, while the cross bolt of chord element 2 is connected to the cross bolt of chord element 3 via another shear connection element 20. This connects the opposing chord elements of the respective opposite spar elements in a crosswise manner. Using the shear connection elements, a first chord element is connected to a second chord element of the opposite spar element.

[0056] The belt elements 1, 2, 3, and 4 can differ in their width, thickness, and material used. Here, different parameters can be selected, particularly in the root segment than in the tip segment (e.g., a larger belt width or GRP instead of CFRP), but differences can also be implemented between the suction and pressure sides (e.g., a greater thickness on the suction side). The connecting plates 7a and 8a on the suction side can also be designed differently in terms of width, thickness, and material selection than the connecting plates 7b and 8b on the pressure side, in order to achieve a load-adapted design with minimal weight.

[0057] A cover 40 is required in the connection area, as shown in Figure 3shown in order not to impair the aerodynamics of the rotor blades and to prevent the ingress of water. This cover 40 can consist of several segments in the circumferential direction of the profile. The cover is connected to the rotor blade on the suction and pressure sides with connecting elements 43, 44, preferably screws. The end faces of the cross bolts 9 preferably serve as screwing points. At the ends 41, 42 of the cover 40, it is connected to the blade as aerodynamically smoothly as possible. An adhesive can be used for this, or the ends 41, 42 consist of a pre-tensioned rubber lip, which rests against the blade segments under pre-tension. The cover 40 increases the profile thickness locally in the connection area by approximately 100 mm (approximately 50 mm each on the pressure and suction sides). Assuming a profile thickness of approximately 700 mm in the connection area, the aerodynamic losses due to the increase in profile thickness are minimal.

[0058] The cross bolts 9 are preferably designed as radially and axially preloaded bolts (so-called RAX bolts) in combination with a radially and axially preloaded bushing 10a, 10b (so-called RAX bushing), as in the Figure 4a and in detail in Figure 4b is shown. Disc and locking elements 11, 12, 13, 14, 15, 16 can be provided.

[0059] The connecting plates 7, 8 are clamped to the belt elements 1, 2 in the axial direction of the cross bolt 9. This creates the desired axial preload in the RAX connection. This axial clamping also ensures that the connecting plates 7, 8 cannot twist under compressive load, as they are frictionally connected to the belt elements 1, 2.

[0060] Alternatively, the push rods 20 can be connected directly to the cross bolts 9 without the washers 15 and 16. This reduces the number of individual parts and creates a positive connection between the push rods 20.

[0061] In an alternative embodiment, the RAX socket 10b is designed without a flange, as shown in Figure 4b shown. This allows for mass and cost savings. Furthermore, the overall height in the axial direction of the bolts is reduced, thus reducing the bending load on the bolts. Furthermore, the projection beyond the aerodynamically optimized profile is reduced. Furthermore, the axial contact pressure on the belt elements 1, 2 is distributed more evenly across the surface of the pulley 11 than with introduction via a flange.

[0062] In a further embodiment, which is described in the Figure 5a and 5bAs shown, the cross bolt 9 is also tapered at its ends. Tapered expansion sleeves 30 and 31 are pressed into the space between holes in the connecting plates 7, 8 and the tapered bolt ends using pressure caps 32, 33 and clamping screws 34. Using the clamping screw 34, the pressure caps 32, 33 are connected to the cross bolt at opposite ends of the cross bolt 9.

[0063] The expansion sleeves 30, 31 are made of a softer metal (e.g., softer steel or aluminum) and are axially slotted one or more times, allowing them to deform plastically and elastically during assembly. This achieves tolerance compensation between the holes in the connecting plates 7, 8 and the axis of the cross bolt 9, allowing for corrective positioning deviations.

[0064] After the expansion sleeve 30, 31 is installed, the connection between the cross bolt 9 and the connecting plates 7, 8 is free of play, thereby increasing the fatigue strength of the connecting plates 7, 8. Furthermore, in this embodiment, the axial space requirement on the inside can be reduced, because the cone, which is formed in the central area of ​​the cross bolt 9 to accommodate the bushing 10b, also serves as a cone for the expansion sleeve 30. This allows the washer 11 to be designed significantly flatter in the form of a pressure piece. Due to the compact design with minimal axial space requirement, this variant has the highest strength and the lowest weight.

[0065] After the expansion sleeves 30, 31 have been pressed in, grub screws 35 are screwed into the pressure caps 32, 33 until the grub screws make contact with the connecting plates 7, 8. A controlled torque is applied to the grub screws 35, whereby the connecting plates 7, 8 are clamped to the pressure pieces 11, 12 and the belt element 1 in the axial bolt direction. This creates the desired axial preload of the RAX connection in the belt element 1. By retightening the grub screws 35, any decrease in axial preload during operation can be compensated for using simple hand tools (torque wrench). Furthermore, it is also possible to retighten the expansion sleeves 30, 31 if they become loose or deformed during operation by retightening the screws 34.

[0066] When installing the cross bolt 9, the bushing 10b must be fixed axially to prevent it from being pushed out of the hole in the belt. For this purpose, an installation tool 50 with a suitable shoulder is suitable, as shown in Figure 6 , which rests against both the washer 12 and the bushing 10b and adjusts their relative axial position. The assembly tool 50 can, for example, be a bolt tensioning cylinder in combination with a tension bolt 51. List of reference symbols

[0067] 1First chord element of the first spar element 2First chord element of the second spar element 3Second chord element of the first spar element 4Second chord element of the second spar element 5Web element of the first spar element 6Web element of the first spar element 7, 8Connecting straps 9Cross bolts 10Conical bushing / clamping bushing 11, 12, 13, 14, 15, 16Disc and locking elements 20Shear connection element 30, 31Expansion sleeve 32, 33Pressure cover 34Clamping screws 35Set screws 40Cover 41, 42Ends of the cover 43, 44Connecting elements of the cover 50Assembly tool 51Tension bolt 100Connecting assembly

Claims

1. Segmented rotor blade for wind turbines with at least two blade segments extending in opposite directions from a joint in a longitudinal direction, each blade segment having at least one internal spar element forming a structural member of the rotor blade, wherein a) the first spar element of the first blade segment and the second spar element of the second blade segment are joined to each other at the joint by means of a connecting arrangement (100) with their front sides, b) wherein the connecting arrangement (100) comprises a plurality of connecting sets, each of which connects the spar elements to one another, c) wherein each connecting set comprises a first transverse bolt (9), a second transverse bolt (9) and at least one connecting strap which has a first strap opening and a second strap opening at its ends, d) wherein, in each connecting set, the first transverse bolt (9) is guided transversely to the longitudinal direction of the rotor blade through a spar opening in the first spar element and the first strap opening of the connecting strap, and the second transverse bolt (9) is guided transversely to the longitudinal direction of the rotor blade through a spar opening in the second spar element and the second strap opening of the connecting strap, so that the connecting strap connects the spar elements to one another, and characterized in that e) at least the first transverse bolt (9) of a first connecting set and the second transverse bolt (9) of a second connecting set opposite the first connecting set are connected to one another via at least a first shear connecting element (20).

2. Rotor blade according to claim 1, characterized in that the second transverse bolt (9) of the first connecting set and the first transverse bolt (9) of the second connecting set are connected to each other via a second shear connecting element (20).

3. Rotor blade according to claim 1 or 2, characterized in that the first spar element and the second spar element each have a first flange element and an opposite second flange element, both of which are connected to one another by at least one web element located therebetween, wherein the transverse bolts (9) are inserted into spar openings of the flange elements transversely to the longitudinal direction of the rotor blade.

4. Rotor blade according to claim 3, characterized in that the first connecting set connects the first flange element of the first spar element (1) to the first flange element of the second spar element (2) and the second connecting set connects the second flange element of the first spar element (3) to the second flange element of the second spar element (4).

5. Rotor blade according to one of the preceding claims, characterized in that the connecting straps (7, 8) have at both ends a head section with the strap openings, which are connected to each other via a connecting section, the width of the connecting section tapering in the middle.

6. Rotor blade according to one of the preceding claims, characterized in that a bushing with a conical inner wall is inserted into at least one spar opening of the spar elements, which cooperates with a transverse bolt (9) with a conical outer wall in the inserted state in such a way that a radial clamping force is applied to the inner wall of the spar opening.

7. Rotor blade according to one of the preceding claims, characterized in that the transverse bolt (9) has a conical outer wall in the area of the strap opening, so that a cavity is formed between an inner wall of the strap opening and the conical outer wall of the transverse bolt (9), into which a conical expansion sleeve (30, 31) is inserted, which is pressed into the cavity by means of a pressure cap (32, 33) arranged on an end face of the transverse bolt (9).

8. Wind turbine with a multi-blade rotor comprising at least one rotor blade according to one of the preceding claims.