Wind turbine blade, ladder support assembly, wind turbine, and method for accessing the interior of a hollow blade of a wind turbine

Abstract

A wind turbine blade including a hollow blade body having a blade root and a base plate disposed at a root end of the blade, the base plate including a manhole allowing access to an interior of the blade, the base plate being provided with attachment means disposed at or near the manhole and configured to directly or indirectly attach at least one ladder to the base plate.

Description

[Technical field]

[0001] The present invention relates to a method for accessing the interior of a hollow blade of a wind turbine, the blade being attached to a rotatable hub of the wind turbine, the interior of the blade being accessible from the hub area through a manhole in a base plate at the root end of the blade, and more particularly to a ladder support assembly and a wind turbine. [Background technology]

[0002] To increase maximum energy output, wind turbines are being built larger. In particular, offshore wind turbines today have rotor blades with root diameters of 3 to 8 meters, and sometimes even larger. Thus, the root end of the blade also has an inside diameter that exceeds the size of an operator, and therefore has parts that are outside the reach of an operator standing inside the hollow blade.

[0003] For some types of blades, it is sometimes necessary to enter the blade, for example to carry out maintenance routines or repair procedures inside the blade. It is therefore known to provide manholes in the base plate of the blade that allow workers to enter the interior of the hollow blade. However, especially for large blades, depending on the respective orientation of the blade or rotor, the manholes may be at a height that is not reachable by workers, and therefore it may not be possible to enter the section of the blade that is behind the base plate.

[0004] Typically, the location of the manhole relative to the entry point into the hub interior can be changed by rotating the rotor of the wind turbine, so that the manhole can be in an accessible position. However, locating the rotor blade in such a position may limit the area of ​​the blade interior that is accessible to workers. For example, if the blade diameter is 3m or more, the position where the interior of the blade can be accessed through the manhole may not allow workers to reach all sections of the blade interior.

[0005] This leads to problems depending on the position of the blade: either the manholes are inaccessible to operators, or, even if they are accessible, not all sections of the inner surface are aligned to the reach of an operator standing inside the blade. Since it is desirable for all sections of the inner surface of the blade to be accessible to perform maintenance procedures, it is necessary to make the blade accessible in various rotor positions. Summary of the Invention

[0006] The invention is based on the object of providing an improved method for accessing the interior of a hollow blade of a wind turbine.

[0007] According to the invention, this problem is solved firstly by a method which is described below. placing the blade in a first position; In this first position, the manhole is accessible to an operator from a footrest inside the hub, the footrest remaining stationary during rotation of the hub; attaching a ladder support assembly to a base plate at or near at least one edge of the manhole; placing the blades in a second position by rotating the hub; In this second position, the distance between the manhole and the footing is greater than in the first position, and mounting at least one ladder to a ladder support assembly for accessing the interior of the blade.

[0008] In a first step, the blade is placed in a first position to allow access to the manhole by an operator standing on a foothold inside the hub. The blade can be placed in the first position by actively rotating the rotor so that the entering blade is in the first position. Alternatively, for example, the rotating rotor can be braked to stop the rotor so that the entering blade is in the first position.

[0009] The blade to be entered has a base plate at its root end, which separates the interior of the hollow blade from the interior of the hollow hub. To access the interior of the blade, a manhole is provided in the base plate. The manhole is, for example, circular or rectangular and has a size that allows an operator to enter the blade. A circular manhole may, for example, have a diameter of 50 cm to 1 m, a rectangular or square manhole may, for example, have an edge length of 40 cm to 1 m.

[0010] In the first position, the manhole is accessible to an operator from the footing inside the hub. Accessible in this case means that an operator can reach the manhole by hand when standing on the footing, in particular by hand all around the manhole. The distance between the top or apex of the manhole and the footing is therefore no more than 1.5 m, respectively. This allows an operator to reach the manhole without hindrance when standing on the footing. The footing can be fixed to the nacelle or other stationary support structure of the wind turbine, for example, so as not to rotate when the rotor of the wind turbine rotates or when the blades rotate around the central axis of the hub, respectively.

[0011] When the blade is in the first position, the ladder support assembly is attached to the base plate. The ladder support assembly is attached at least to the edge of the manhole or immediately adjacent to the edge of the manhole. The ladder support assembly can be attached to the base plate, for example, by bolting the ladder support assembly to each opening in the base plate. The manhole can initially be covered with a cover, which is removed before attaching the ladder support assembly to the manhole. The bolt holes used to secure the cover can also be used to secure the ladder support assembly to the base plate.

[0012] The rudder support assembly is attached to the blade at a first position, but is not yet used to enter the blade. Once the blade is in the first position, the rudder support assembly can be attached to the base plate without any problems, i.e., in a position that is easily accessible to the operator. Naturally, when the rotor blade rotates from the first position to the second position, the rudder support assembly also changes its position. Thus, the rudder support assembly is already attached for the subsequent second blade position, and the rudder support assembly allows the rudder to be correctly secured when the rotor blade rotates to the second position.

[0013] After the ladder support assembly is attached to the base plate, the blade to be entered is placed in a second position by rotating either the hub or the rotor of the wind turbine blade. In the second position, the manhole and the footing are farther apart than in the first position. In particular, the distance between the manhole and the footing may be so far that a worker standing on the footing cannot reach the manhole. In particular, the distance between the lower edge of the manhole and the footing in the second position may be 1.5 m or more, in particular 2 m or more. In the second position, at least one ladder is attached to the ladder support assembly to access the inside of the blade. After the ladder is attached to the ladder support assembly, a worker can use the ladder to enter the blade from the manhole.

[0014] The solution according to the invention has the advantage that in the second position it is possible to use the ladder to enter the interior of the hollow blade, even if the manhole is located so far away from the footing that the worker cannot enter without using the ladder.

[0015] By placing the blade in the first position, the ladder support assembly can be installed without interfering with the manhole of the blade, and, for example, if maintenance procedures must be performed on the entire inner surface of the blade, workers can also enter the blade in the first position and perform the respective maintenance or repair procedures in the areas accessible in the first position.

[0016] After the blade is rotated to the second position, the blade's orientation relative to the stationary footing has changed due to the rotation of the blade, and therefore the area of ​​the blade's inner surface that is accessible to the operator has changed. Specifically, for example, when the blade is rotated by 180 degrees, the area that was below the blade in the first position becomes above the blade in the second position, and vice versa.

[0017] The method according to the invention has the advantage that by mounting the ladder support assembly at the first blade position, the ladder can be mounted to the ladder support assembly at the second blade position to allow safe entry to the blade. It is also advantageous in that mounting the ladder is easy as it can be mounted at the second blade position already in the correct orientation for manhole entry. It is also advantageous in that it avoids mounting the ladder upside down at the first blade position, which would be tedious and difficult.

[0018] In particular, the method may be carried out on blades with a root diameter of 2 m or more, in particular 3 m or more or 5 m or more. For example, the root diameter of a wind turbine blade may be between 2 m and 15 m, in particular between 3 m and 8 m.

[0019] The method according to the invention has the further advantage that it is not necessary to pitch the blades in order to change the position of the manholes relative to the footing inside the hub. Normally, the turbine blades are pitched by about 90° to change the position of the manholes in the base plate of the blades relative to the stationary footing. However, since the rotor is stopped during maintenance procedures, a change in the pitch of the blades is not desirable since the blades are usually pitched to a parking position, in which there are no or at least not large forces acting on the rotor from the wind acting on the front side of the rotor. The method according to the invention also has the advantage that the blades can be brought to another position, so that the pitching of the blades and thus the generation of undesirable loads on the components of the wind turbine, in particular the main bearings, the shaft, the brakes used to fix the rotor, etc., can be avoided.

[0020] Access to various sections of the inner surface of the wind turbine blade may be required, for example, to check the condition of the shell of the blade and / or to perform repair procedures, for example, above and below the webs that run through the interior of the blade. Also, certain sensors, for example LOPC sensors, may need to be accessed frequently during the course of maintenance procedures. Such sensors may be located, for example, at 3, 6, 9 and 12 o'clock positions around the essentially circular root portion of the wind turbine blade. In larger blades, a sensor located at the 12 o'clock position may not be reachable by an operator standing on the underside of the blade, i.e. at the 6 o'clock position. According to the method according to the invention, the sensor at the 12 o'clock position can be reached using a ladder and ladder support assembly when the blade is placed in the second position.

[0021] Preferably, in the first position the blade is oriented at an angle of 90° to 120°, in particular an angle of 105°, relative to the vertically upward position of the blade, and / or in the second position the blade is oriented vertically upward or at an angle of 255° to 285°, in particular an angle of 270°.

[0022] The vertical up position of the blade corresponds, for example, to a 0° position. The angle between the vertical up and the position of the blade can be measured in either a clockwise or counterclockwise direction, depending, for example, on the position of the manhole or the eccentric offset of the manhole relative to the center point of the base plate.

[0023] In a preferred embodiment of the invention, the ladder support assembly is mounted at least at or near the top edge of the manhole in a first position of the blade, and when the blade is rotated to the other side of the hub, the ladder support assembly is disposed at the lower end of the manhole to facilitate easy access to the blade using a ladder mounted to the ladder support assembly, particularly when the entering blade has rotated approximately 180 degrees.

[0024] Preferably, the ladder support assembly comprises at least one frame- or plate-shaped, in particular ring- or split-ring-shaped, support segment attached to the base plate so as to at least partially surround the manhole. The support segment allows for the attachment of another component of the ladder support assembly to the manhole, in particular perpendicular to the opening. The ladder, which is attached to the ladder support assembly when the blade is rotated to the second position, can be attached directly to the support segment or to another component of the ladder support assembly which is attached to the support segment when the blade is in the first position.

[0025] Preferably, the ladder support assembly includes at least one platform segment that is positioned at the manhole such that the platform segment extends through the manhole and / or is positioned below the manhole when the blade is in the second position. In particular, the platform segment can be used when rotating the blade to a second position that is different from the vertical orientation of the rotating blade. The platform segment facilitates passage of an operator through the manhole when the operator, for example, walks or crawls on the platform segment through the manhole.

[0026] Further components of the ladder support assembly can be attached to the platform segment, for example one or more handrails and / or one or more support posts, which support the platform segment relative to the support segment and / or to the base plate. The platform segment can include one or more attachments for fastening the one or more ladders, or one or more attachments can be attached to the platform segment. These components are attached at a first blade position and their orientation is adjusted to be appropriately used when the incoming blade rotates to the second position.

[0027] In a preferred embodiment, at least one ladder is hung on the ladder support assembly. When the rotor blades rotate to the second position, one ladder can be attached to the ladder support assembly by hanging on the ladder support assembly, in particular by hanging on the mounting part of the ladder support assembly. The mounting part can include, for example, one or more hooks to which the top part of the ladder can be attached. Alternatively, the ladder can include one or more hooks at its top, which engage with corresponding corresponding parts on the mounting part of the ladder support assembly. After being attached to the ladder support assembly, the ladder can be fixed by at least one fixing mechanism and / or by using one or more fastening means, such as bolts.

[0028] The ladder may include one or more support segments, which allow supporting the ladder relative to the base plate of the wind turbine blade, especially if a platform of ladder support assemblies is used. In this case, the ladder is suspended on the edge of the platform segment spaced apart from the manhole, so that a gap also remains between the ladder and the base plate of the blade. This gap can be bridged by one or more support structures, for example support feeds. The support structures can be attached to the ladder before or after mounting the ladder on the ladder support assembly, supporting the ladder relative to the base plate and facilitating access to the manhole.

[0029] Preferably, two ladders are attached to the ladder support assembly, with a first ladder located on the side of the base plate facing the inside of the hub and a second ladder located on the side of the base plate facing the inside of the blade, allowing one to climb up from a footrest in the hub, through a manhole, and then use the second ladder to descend from the manhole to the inside of the blade on the opposite side of the base plate.

[0030] In a preferred embodiment, the second ladder is attached to the ladder support assembly by sliding it through the manhole toward the interior of the blade where the ladder support assembly is located and locking onto the ladder support assembly, particularly by hanging from the ladder support assembly. The second ladder can be slid, for example, over a platform segment of the ladder support assembly or another guide structure. The second ladder can be attached to the ladder support assembly by hanging from the ladder support assembly, with the ladder extending from the ladder support assembly toward the bottom of the interior of the blade it is entering.

[0031] Like the first ladder, the second ladder may also be hung over the edge of the platform segment spaced from the manhole, leaving a gap between the ladder and the base plate of the blade. This gap may be bridged by one or more support structures, such as support feeds, which may be attached to the second ladder before or after it is attached to the ladder support assembly, to support the second ladder against the base plate and facilitate access to the manhole.

[0032] A ladder support assembly for a wind turbine according to the invention comprises at least one frame- or plate-shaped, in particular ring- or split-ring-shaped, support segment which is mountable to a base plate of a wind turbine blade at least partially surrounding a manhole in the base plate, and which comprises at least one attachment for attaching a ladder to the ladder support assembly. The frame- or plate-shaped support segment is mounted to the base plate at or near the manhole and provides at least one attachment for attaching the ladder to the ladder support assembly, in particular by hanging one side of the ladder on the ladder support assembly.

[0033] Preferably, the ladder support assembly includes two mounting sections, each located on an opposite side of the base plate when the ladder support assembly is in an installed state, one of the mounting sections usable to mount a first ladder to allow climbing up from the footing in the hub towards the manhole, and the other of the mounting sections usable to mount a second ladder to allow climbing down from the manhole into the interior of the blade.

[0034] Preferably, the ladder support assembly includes at least one platform segment that is positionable relative to the manhole such that the platform segment extends through the manhole and / or is positioned on one side of the manhole to allow an operator to exit the manhole by passing over the platform segment. In particular, the platform segment may be mounted or mountable orthogonally or essentially orthogonally to a support segment attached to the rim of the manhole.

[0035] A wind turbine according to the invention comprises at least one ladder support assembly according to the invention. The wind turbine comprises at least one blade having a base plate for mounting the ladder support assembly. Preferably, all blades of the wind turbine are adapted for mounting the ladder support assembly. The wind turbine may comprise in particular three blades mounted on the hub of the wind turbine. The ladder support assembly may be stored inside the wind turbine, for example in the hub or in the nacelle adjacent to the hub. In addition to the ladder support assembly, one or more ladders, which may be mounted on the ladder support assembly, may also be stored in the wind turbine.

[0036] The invention further relates to a wind turbine blade comprising a hollow blade body having a blade root and a base plate arranged at the root end of the blade, the blade according to the invention comprising a manhole through which the interior of the blade is accessible, the base plate being provided with attachment means arranged at or near the manhole and configured to attach directly or indirectly at least one ladder to the base plate.

[0037] According to one embodiment, the base plate is provided with no more than one manhole. This results in an optimal configuration of the base plate with respect to structural loads. The blade contains only one manhole and no other openings of comparable size through which a person can pass. The central purpose of the base plate is to increase the stiffness of the blade at the root end. This function is weakened if a large number of manholes are provided to allow access to the interior at various positions. A base plate with multiple manholes must therefore have a comparable weight in order to be sufficiently stiff to perform its stiffening function. As the blade according to the invention contains only one manhole, the stiffness of the base plate is high and no measures need to be taken to increase the stiffness. Furthermore, the base plate is provided with attachment means arranged at or adjacent to the single manhole and arranged to attach at least one ladder directly or indirectly to the base plate. The attachment means allow the attachment of a ladder which can be used by maintenance personnel to reach the manhole if it is located too far from the footing. If the manhole is close enough to the footing, the maintenance personnel can access it directly from the footing. On the other hand, when the manhole is rotated to a position that is not directly reachable from the footing, the personnel can easily attach the ladder to the attachment means and use this ladder to climb up to the manhole. The attachment means may also be configured to attach the ladder directly to the attachment means without the use of other fixing or mounting implements or tools. In this case, the attachment means already comprises, for example, a hook like mounting interface to which the ladder can be directly attached. Alternatively, the attachment means is configured to indirectly fix the ladder using some additional mounting or fixing implement or tool, which is attached to the attachment means if necessary and which finally attaches the ladder. The attachment means may also be arranged directly on the manhole, meaning that it is arranged as close as possible to the manhole.Alternatively, the attachment means may be located some distance from the manhole, provided that the manhole can be easily reached by personnel using the attached ladder.

[0038] The blade according to the invention is thus improved with regard to its rigidity, with regard to the respective set-up and with regard to easy access through a manhole even if it is located away from the footing.

[0039] The mounting means are preferably configured to mount, directly or indirectly, a first ladder on a first side of the base plate facing away from the interior of the blade and a second ladder on a second side of the base plate facing the interior of the blade, thereby allowing the first ladder to be located directly or indirectly on the outside of the base plate to enable a worker standing on the footing to climb up to the manhole and the second ladder to be located on the inside of the base plate to enable a worker to descend after passing through the manhole. The base for mounting of both ladders is a common mounting means.

[0040] The attachment means can be permanently arranged on the base plate, meaning that the attachment means are permanently and rigidly attached to the base plate, for example by welding. Alternatively, the attachment means can be removably arranged on the base plate. The attachment means can be fixed, for example by screws or clamps, when the blades are assembled when the turbine is built or after the blades have been attached to the hub. In this case, they can always be removed if required.

[0041] As mentioned above, the base plate contains only one manhole. The manhole is preferably circular or elliptical. This geometric shape can be easily cut from a regular metal base plate and does not significantly affect stability. It is not too large, but it is suitable for a person to easily pass through it.

[0042] The attachment means can be said to be the central item of the blade. It is preferably or comprises at least one frame- or plate-shaped support segment adapted to at least partially surround the manhole. Such a frame- or plate-shaped support segment provides a sufficiently stable attachment interface for the attachment of either a ladder or additional attachment equipment. This is particularly true if the attachment means is removably arranged on the base plate, for example the frame- or plate-like design makes it possible to provide sufficient fixing elements for a firm attachment to the base plate, preferably fixing elements in the form of clamps or the like fixed to the base plate edge extending around the manhole.

[0043] Preferably, the geometric shape of each support element of the mounting means is in some way adapted to the shape of the manhole. If the manhole is preferably circular or elliptical, the support elements are preferably U-shaped, circular, elliptical or polygonal. These geometric shapes allow the support elements to surround the manhole to a certain extent. However, even if the manhole is, for example, rectangular, the U-shaped or polygonal support elements can at least partially surround the manhole.

[0044] According to another aspect of the invention, the attachment means may include two or more separate attachment positions assigned to different positions of the support element. As described, the blade may be placed in different rotational positions depending on which area of ​​the interior of the blade needs to be maintained. Thus, the manhole may be placed closer to the footing or further away from the footing. If only one set attachment position for the ladder is provided on the support element, the blade can be placed in a first position closer to the footing and in a second position rotated, for example 180° relative to the first position, where the manhole is higher above the footing. On the other hand, if the support element is provided with two or more set attachment position interfaces, it is possible to rotate the blade also to set intermediate positions where the ladder can be easily fixed to the support element. This gives more flexibility in terms of possible maintenance positions and allows different blade areas to be brought into good positions for the next maintenance. Each attachment position or attachment interface is realised by a fixing means or element configured to receive the ladder directly or to receive a separate attachment for fixing the ladder.

[0045] Preferably, each mounting position fixing means or fixing element defining a mounting position is assigned to a separate circumferential position, which is particularly preferred when the support element has a closed form, such as a circular, elliptical or polygonal form. In particular, in a polygonal form, such as a rectangular form or a hexagonal or octagonal form, with a certain number of linear support element members making up the geometric shape, it is easily possible to provide each of the support element members with a mounting element or interface, so that the blades can be positioned in four different positions in the case of a rectangular support element, six positions in the case of a hexagonal form and eight positions in the case of an octagonal form. However, other polygonal forms are also feasible.

[0046] Finally, the base plate may be a single plate provided with the manhole and the attachment means. Alternatively, the base plate may comprise a first plate with a first manhole opening and a second plate arranged parallel to the first plate with a second manhole opening, which manhole openings are at the same height as each other to form a manhole. This base plate is a double plate structure with two parallel plates arranged parallel and adjacent to each other, both plates containing manhole openings, both manhole openings being at the same height to form a manhole. The attachment means in this case may be in the form of an attachment only to the outer first plate, and may, if necessary, fix additional attachments allowing at least a second inner ladder or both ladders to be arranged.

[0047] All details and advantages described in relation to the method according to the invention apply equally to the ladder support assembly according to the invention and to the wind turbine according to the invention, and therefore also details and advantages described in relation to the ladder support assembly according to the invention apply equally to the method according to the invention and to the wind turbine according to the invention and vice versa. [Brief description of the drawings]

[0048] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings, which are merely principle sketches designed for illustrative purposes and are not intended to limit the invention. [Figure 1] 1 is an embodiment of a wind turbine according to the present invention. [Diagram 2] A wind turbine rotor with the incoming blade in the first position. [Diagram 3] A wind turbine rotor with the incoming blade in the second position. [Figure 4] A detailed view of the base plate of an incoming wind turbine blade. [Diagram 5]FIG. 13 is a detailed view of a manhole in a base plate with attached support segments of an embodiment of a ladder support assembly according to the present invention. [Figure 6] Manhole with ladder support assembly installed. [Figure 7] FIG. 13 is a cross-sectional view showing the installed rudder support assembly with the entering blade in a second position. [Figure 8] A second rudder attached to a rudder support assembly inside the entering blade. [Figure 9] FIG. 2 is a partial view of a wind turbine blade facing the blade root and provided with attachment means including multiple attachment locations for a ladder; [Figure 10] FIG. 2 is a cross-sectional view of a blade including a base plate having first and second plates and mounting means thereon having first and second ladders attached thereto; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] An embodiment of a wind turbine 1 is shown in Figure 1. The wind turbine 1 includes a tower 2 that supports a nacelle 3 of the wind turbine 1. A rotor 4 is attached to the front of the nacelle 3 and includes a hub 5 and a number of rotor blades 6. During operation of the wind turbine 1, the rotor 4 rotates and drives a generator (not shown) of the wind turbine 1 to generate primarily electrical energy.

[0050] 2 shows the rotor 4 in detail. The rotor 4 has three rotor blades 6. The rotor blades 6 are attached to the hub 5 at their root ends 8 opposite their tips 9. The interiors 10 of the blades 6 are at least partially hollow and are each surrounded by a shell 11 of the blade 6. The blades 6 have a base plate 12 at each of their root ends 8.

[0051] In order to carry out a maintenance routine or repair procedure in the interior 10 of one of the wind turbine blades 6, it may be necessary for a worker to access the interior 10 of the wind turbine blade 13 to enter. However, in particular if the rotor blade 6 has a large diameter at its root end, not all areas of the inner surface of the shell 11 are reachable by a worker standing inside the blade. In particular, since the wind turbine blade 6 may have a diameter of 2 m to 15 m at the root end 8, in particular a diameter of 3 m to 8 m, a worker standing below cannot reach elements or sections of the shell 11 located at the top of the blade 13.

[0052] To facilitate understanding of the orientation of the blade 13 to be repaired, an arrow 7 is shown in Figure 2, where the blade 13 to be entered is located in a first position. In this first position, the arrow 7 points from the underside of the blade 13 to the top. The blade in the first position is located at an angle α = 105°, measured counterclockwise when looking from the front of the rotor 4, or clockwise when standing in the nacelle looking towards the hub, relative to the vertical direction indicated by the dashed line 15.

[0053] In figure 3 the rotor 4 is shown after rotation, with the incoming rotor blades 13 now disposed in a second position, where the blades are oriented at an angle α = 270°. The relative direction of the arrow 7 to the blades 13 has not been altered to illustrate the effect of rotation of the orientation of the blades 13.

[0054] As can be seen from arrow 7, the orientation of the blade 13 and its sections of shell 11 changes from a first position to a second position, so that areas or components of the blade 13 that were at the top of the blade 13 in the first position are now at the bottom, and vice versa. Specifically, when servicing large blades, such as those with a diameter of 3m or more, rotating the blade during a maintenance procedure allows a worker to reach all relevant components or sections of the shell 11 from inside the blade 10.

[0055] 4 shows a detail of the base plate 12 of the wind turbine blade 6. To allow access to the interior 10 of the blade 6 from the hub 5, the base plate 12 is provided with a manhole 14. To access the interior 10 of the blade 13, workers must pass through the manhole 14, which is formed as an opening in the base plate 12.

[0056] The illustrated manhole 14 is shown as being circular, with a diameter that allows an operator to pass through the manhole 14. The manhole 14 may have a diameter of, for example, 50 cm to 1 m. The manhole 14 may also have other shapes, for example a rectangular or square manhole 14 with sides measuring 40 cm to 1 m.

[0057] The manhole 14 is offset from the center 16 of the base plate 12 so that the manhole 14 changes position when the blade 13 rotates to the second position as shown in Figure 3. The position of the manhole 14 in the second blade position is indicated diagrammatically by the dashed line 17.

[0058] In the first blade position, an operator can access the manhole 14 from a foothold 18 installed inside the hub 5. For example, the distance between the top end of the manhole 14 and the top surface of the foothold 18 is 1.5 m or less.

[0059] In contrast, in the second position, the distance between the manhole 14 and the footing 18 is greater than in the first position. The distance from the footing 18 to the bottom of the manhole 14 can be, for example, greater than 1.5 m, and in particular, greater than 2 m or 2.5 m.

[0060] The footing 18 is stationary and does not change position when the rotor 4 of the wind turbine blade 1 rotates or when the blade 13 moves from a first position to a second position. For example, the footing 18 may be the upper surface of a platform that is fixed to the nacelle 3 or to another structural element of the nacelle 3.

[0061] For example, in a repair procedure that requires access to four sensors that are equidistantly spaced around the inner circumference of the wind turbine blade 6, access to the blade 13 in both the first and second positions is required to access all of the sensors. The sensors may be specifically located at the 3 o'clock, 6 o'clock, 9 o'clock, and 12 o'clock positions around the inner circumference of the blade 13 in the first blade position. For particularly large blades, the top sensor at the 12 o'clock position may not be accessible when the blade is oriented in the first position. However, this sensor will be at the 6 o'clock position when the blade is rotated to the second position, and thus will be located lower inside the hollow blade 6 and easily accessible to the operator.

[0062] In one embodiment of a method for accessing the interior 10 of a hollow blade 6 of a wind turbine 1, the to-be-entered blade 13 is first positioned in a first position, as illustrated in Figure 2. In the first position, a manhole 14 in the base plate 12 is accessible to an operator from a footwell 18, as can be seen in Figure 4. To allow access to the blade 13 in the second position, a ladder support assembly 19 is attached to the base plate 12 at or near the manhole 14 when the to-be-entered rotating blade 13 is positioned in the first position.

[0063] 5 shows the manhole 14 in the base plate 12 in detail in the first blade position of the blade 13. A ladder support assembly 19 is attached to the edge of the manhole 14. The ladder support assembly 19 comprises at least one support segment 20 attached to the base plate 12 adjacent the manhole 14. In the embodiment shown, the ladder support assembly 19 comprises two separate plates 21, 22, which are split ring-shaped plates, attached to the base plate 12 around the periphery of the manhole 14. The support segment 20 comprises a flat portion 23 which is located on the upper edge 24 of the manhole 14 when the manhole 14 is in the first position.

[0064] As shown in Figure 6, the other components of the ladder support assembly 19 can be assembled when the incoming rotating blade 13 is in the first position. The ladder support assembly 19 includes a platform segment 25 that is disposed on a flat portion 23 of the support segment 20. The ladder support assembly 19 further includes two handrails 26, 27 that are attached to the platform segment 25 and are used to support the platform segment 25 relative to the support segment 20 and the base plate 12. The handrails 26, 27 can be attached to the platform segment 25 and / or to the support segment 20 by, for example, a number of bolt connections 28.

[0065] The platform segment 25 is attached to the flat part 23 of the support segment and thus to the upper edge of the manhole 14 in a first position, as the blade 13 is rotated to a second position before entering the manhole 14. The platform segment 25 thus changes its position, in particular so that the platform segment 25 is located at the lower edge of the manhole 14 after the blade has been rotated to the second position.

[0066] After mounting the ladder support assembly 19 in the manhole 14 or on the base plate 12, the blade 13 rotates to a second position. In the direction of view from inside the nacelle 3 looking towards the center of the hub 5, the incoming rotor blade 13 may rotate, for example, from the right side to the left side or vice versa. The rotation of the blade 13 also causes the base plate 12 to rotate (revolve) about the central axis of the rotor 4, and the base plate 12 is disposed in a second position that is at least essentially upside down with respect to the first position.

[0067] 7 shows a cutaway view of the base plate 12 with the incoming blade 13 rotated to a second position. The rotor blade 13 is on the left side of the base plate 12 and the hub is on the right side.

[0068] In this second position, the distance between the manhole 14 and the stationary footing 18 is greater than in the first position. The platform segment 25 includes a mounting portion 29 for mounting the ladder 30 to the ladder support assembly 19. In this embodiment, for example, the top rung 31 of the ladder 30 is attached to the mounting portion 29 that includes two hooks 32 for suspending the ladder 30 from the ladder support assembly 19. Note that the handrails 26, 27 are omitted in Fig. 7 for clarity. The ladder 30, which is attached to the ladder support assembly 19 at the hub side, is supported on the base plate 12 by a support portion 33.

[0069] A ladder 34 is also mounted on the ladder support assembly 19 so as to be able to enter the interior of the hollow blade, which is located on the left hand side in Figure 7. This other ladder 34 is mounted on another mounting part 35 of the ladder support assembly 19. This mounting part 35 may, for example, comprise one or more hooks 36 on which the ladder 34 may be hung.

[0070] To position the alternative ladder 34 on the blade side of the base plate 12, the alternative ladder 34 can be slid into the ladder support assembly 19, for example into the platform segment 25, through the manhole 14. The insertion of the ladder 34 is shown diagrammatically in dashed lines in Figure 7. The alternative ladder 34 can also include a support 33 for supporting the ladder against the blade side of the base plate 12. The support can specifically be attached prior to mounting the alternative ladder 34 to the ladder support assembly 19.

[0071] FIG. 8 shows a view of the blade side of the base plate 12. Another ladder 34 is attached to the ladder support assembly 19 located on the underside of the manhole 14. Workers who must enter the hollow interior of the blade 6 can walk or crawl through the manhole 14 on the platform segment 25. The ladder is hung from the ladder support assembly 19, for example, by hooking the top rung 37 of the ladder 34 onto the hook 36 of the mounting portion 35. With both ladders vertically aligned toward the lower edge of the manhole 14 in the second blade position, the worker can climb up the footboard 18, onto the platform segment 25 of the ladder support assembly 19, and then climb down into the blade.

[0072] After performing the necessary maintenance routines and / or repair procedures, the rudders 33, 34 and rudders support assembly 19 can be removed by performing the steps described above in reverse order. The wind turbine 1 includes the rudders support assembly 19 and / or the rudders 33, 34, which can be stored, for example, inside the hub 4 and / or inside the nacelle 3.

[0073] In an alternative embodiment of the method for gaining access to the inside of one of the blades 6, the blade 13 to be entered can be placed in a second position with an angle α=0° pointing vertically upwards. In this case, the blade can be accessed by a ladder hung on a ladder support assembly 19. The ladder is then positioned at least essentially perpendicular to the base plate 12 and allows an operator to climb it and enter the blade through a manhole 14.

[0074] In this case, the support segment 20 of the ladder support assembly 19 attached to the edge of the manhole 14 may include a mounting portion 29 with two hooks, for example as described above, oriented such that the ladder can be hung on the ladder support assembly 19 when the blade 13 is in the second vertical position. In this embodiment, the platform segment 25 and / or the handrails 26, 27, respectively, are not attached to the support segment 20 and may be omitted.

[0075] Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the disclosed embodiments, and those skilled in the art can derive other modifications from these embodiments without departing from the scope of the present invention.

[0076] FIG. 9 illustrates the main part of a wind turbine blade 6, which normally has an outer shell 11 and a root part with a root end 8 to which a base plate 12 is attached. The figure shows a perspective towards the root part. The base plate 12, like the previous embodiment, has only one manhole 14, which is arranged eccentrically with respect to the centre 16. The base plate 12 is provided with a mounting means 38, which comprises a frame-like support segment 20 and optionally some additional mounting devices or elements. The support segment 20 of the mounting means 38 is in this example polygonal, here rectangular. The support segment 20 of the mounting means (and some additional fastening devices or elements) is permanently attached to the base plate. Permanent in this case means that the support segment of the mounting means (and optional fastening devices) is already attached to the base plate at the blade manufacturing site and can remain on the base plate when the blade is attached to the respective hub and can remain throughout the life of the blade when the wind turbine is finally assembled and in operation. The attachment can be permanent or removable. This can be achieved, for example, by welding the support segments 20 to a metal base plate or by using fastening means such as screws or bolts and nuts or clamping elements.

[0077] The support segment 20 is placed close to the manhole 14 and completely surrounds it like a frame. The rectangular support segment 20 comprises four longitudinal support elements 39a, 39b, 39c, 39d. Two of these elements, namely 39b and 39c, are provided with fastening means 40b and 40c. The fastening means 40b and 40c can be any type of fastening element providing either a fastening interface for attaching the ladder directly to the support segment 20 or some additional fastening device for finally attaching the ladder so that it is indirectly fixed to the support segment 20. The fastening means are therefore placed at different circumferential positions relative to the centre of the manhole 14 or to the frame-type shape of the support segment 20.

[0078] When the blade is in a rotational position in which the manhole is close to the footing 18 as shown, the worker has direct access to the manhole 14 from the footing 18. This allows inspection and work on the lower blade body area below in this rotational position. When a surface area located further to the right of the blade has to be maintained, the blade is rotated clockwise by approximately 90°, so that the manhole 14 together with the support segment 20 is in the upper left position shown in dashed lines. After a rotation of 90°, the support element member 39b is now in a lower position together with its fixing means 40b, where a ladder can be attached to allow the worker to reach the manhole 14 raised from the footing 18. When another internal area has to be maintained, the blade is rotated another 90° clockwise so that the manhole 14 is in the upper right position. In this position, the support element member 39c together with its fixing means 40c is at its lowest and here a ladder can be fixed. The area opposite to the area below in the first rotational position is now available for maintenance. Finally, by rotating the blade clockwise again by 90°, another interior area can be sent into position for maintenance. The manhole 14 is now again in a lowered position directly accessible from the footing 18, without the need for a ladder. In this way, each position can be directly reached. In this embodiment, each interior area can be brought into a good position for maintenance work, and the manhole is always easily accessible to the operator, either directly from the footing or via an attached ladder. The ladder can be firmly and safely attached to the support segment in the designated rotational position where the ladder is needed to reach the manhole 14.

[0079] The rectangular design shown is merely exemplary: the support segments 20 with one or more fastening means may have various shapes, for example circular or polygonal, as well as rectangular. A U-shape is also feasible, in which case they may partially surround the manhole 14 and each be provided with a fastening means.

[0080] Figure 10 shows a cutaway view of the blade 6 at the root end 8, showing the base plate 12, which is a kind of sandwich structure of two separate plates. The base plate 12 consists of a first plate 41 close to the open end of the root end 8 and a second plate 42 facing towards the inside of the hollow blade body. The plates 41, 42 are of similar size and are arranged parallel and close to each other. The first plate 41 is provided with a first manhole opening 43 and the second plate 42 with a second manhole opening 44. Both manhole openings 43, 44 are at the same height and form a common manhole 14.

[0081] The support segment 20 is provided with a mounting means 38, which is permanently attached to a first plate 41 facing the open end of the root end 8, to which the first ladder 30 is attached. The mounting means comprises a hook 32 which may form the fastening means described in relation to FIG. 9. As an additional and also permanent fastening device, a mounting part 35 with another hook 36 is attached to the support segment 20. The mounting part 35 extends through the manhole, i.e. through both manhole openings, so that the hook 36 is inside the second plate 42. The second ladder 34 is attached to the hook 36. A worker can use the first ladder 30 to climb up to the manhole 14 and use the second ladder 34 to descend to the maintenance area, or vice versa.

Claims

1. A wind turbine blade (6, 13) comprising a hollow blade body having a blade root portion and a base plate (12) disposed at a root end portion (8) of the blade (6), wherein the base plate (12) includes a manhole (14) that enables passage into the interior of the blade (6), and attachment means (38) are provided on the base plate (12), the attachment means (38) being arranged in or in the vicinity of the manhole (14) and configured to attach at least one ladder (30, 34) directly or indirectly to the base plate (12).

2. The wind turbine blade (6, 13) according to claim 1, wherein the base plate (12) includes one manhole (14) and does not include more than one manhole (14).

3. The attachment means (38) is configured to directly or indirectly attach a first ladder (30) to a first side of the base plate (12) facing away from the interior of the blade (6), and directly or indirectly attach a second ladder (34) to a second side of the base plate (12) facing towards the interior of the blade (6), the wind turbine blade (6, 13) according to claim 1.

4. The attachment means (38) is arranged on the base plate (12) such that it cannot be removed, or the attachment means (38) is removably arranged on the base plate (12), the wind turbine blade (6, 13) according to claim 1.

5. The manhole (14) is circular or elliptical, the wind turbine blade (6, 13) according to claim 1.

6. The mounting means (38) is at least one frame-shaped or plate-shaped support segment (20) that at least partially surrounds the manhole (14), or the wind turbine blade (6, 13) according to claim 1, which includes the support segment (20).

7. The shape of the support segment (20) is U-shaped, circular, elliptical, or polygonal, for the wind turbine blade (6, 13) according to claim 6.

8. The mounting means (38) includes two or more different mounting positions assigned to different positions of the support segment, for the wind turbine blade (6, 13) according to claim 1.

9. The different mounting positions are assigned to different positions in the circumferential direction, for the wind turbine blade (6, 13) according to claim 8.

10. The base plate (12) is a single plate, or The base plate (12) includes a first plate (41) having a first manhole opening (43) and a second plate (42) arranged parallel to the first plate (41) and having a second manhole opening (44), and the first and second manhole openings (43, 44) are at the same height from each other to form the manhole (14), for the wind turbine blade (6, 13) according to claim 1.

11. A ladder support assembly for a wind turbine, The ladder support assembly (19) includes at least one frame-shaped or plate-shaped support segment (20), the support segment (20) is attached to the base plate (12) of the wind turbine blade (6, 13), and at least partially surrounds the manhole (14) in the base plate (12), The ladder support assembly (19) includes at least one attachment part (29, 35) for attaching a ladder (30, 34) to the ladder support assembly (19), and / or The ladder support assembly (19) is a ladder support assembly configured to be attached to the wind turbine blade (6, 13) according to claim 1.

12. The ladder support assembly (19) includes two attachment portions (29, 35), In a state where the ladder support assembly (19) is attached, each of the attachment portions (29, 35) is disposed on the opposite side of the base plate (12), respectively, of the ladder support assembly according to claim 11.

13. The ladder support assembly (19) includes at least one platform segment (25), The ladder support assembly (19) is arranged such that the platform segment (25) extends through the manhole (14) and / or the platform segment (25) is disposed on one side of the manhole (14), and is arranged in the manhole (14) to allow an operator to pass through the platform segment (25) and pass through the manhole (14), the ladder support assembly according to claim 11 or 12.

14. A wind turbine comprising at least one wind turbine blade (6, 13) according to claim 1 and / or at least one ladder support assembly (19) according to claim 11.

15. A method that enables passage into the interior of the hollow blade (6, 13) of a wind turbine (1), The blade (6, 13) is attached to a rotatable hub (5) of the wind turbine (1), and the interior (10) of the blade (6) can enter from the hub (5) through a manhole (14) in a base plate (12) at the root end (8) of the blade (6, 13), The method includes, disposing the blade (6, 13) in a first position, At the first position, an operator can access the manhole (14) from a staging surface (18) inside the hub (5), and the staging surface (18) remains stationary when the hub (5) rotates. Attaching a ladder support assembly (19) to the base plate (12) at or near at least one edge of the manhole (14). Rotating the hub (5) to place the blades (6, 13) in a second position. At the second position, the distance between the manhole (14) and the staging surface (18) is greater than that at the first position. Attaching at least one ladder (30, 34) to the ladder support assembly (19) to enter inside the blades (6, 13). A method comprising the steps.

16. At the first position, the blades (6, 13) are oriented at an angle of 90° to 120° with respect to the vertically upward position of the blades (6, 13). And / or At the second position, the blades (6, 13) are vertically upward or oriented at an angle of 255° to 285°. The method according to claim 15.

17. The ladder support assembly (19) is attached to at least the upper edge of the manhole (14) or near the upper edge when the blades (6, 13) are in the first position. The method according to claim 15.

18. The ladder support assembly (19) includes at least one frame-shaped or plate-shaped support segment (20), and the support segment (20) is attached to the base plate (12) so as to at least partially surround the manhole (14). The method according to claim 15.

19. The ladder support assembly (19) includes at least one platform segment (25). The ladder support assembly (19) is arranged in the manhole (14) such that the platform segment (25) extends through the manhole (14) and / or such that the platform segment (25) is disposed below the manhole (14) when the blades (6, 13) are in the second position, the method according to claim 15.

20. The at least one ladder (30, 34) is hung on the ladder support assembly (19), the method according to claim 15.

21. Two ladders (30, 34) are attached to the ladder support assembly (19), A first ladder (30) of the two ladders (30, 34) is disposed on the side of the base plate (12) facing the inside of the hub (5), A second ladder (34) of the two ladders (30, 34) is disposed on the side of the base plate (12) facing the inside of the blades (6, 13), the method according to claim 15.

22. The second ladder (34) is attached to the ladder support assembly (19) by sliding over the ladder support assembly (19) through the manhole (14) and towards the inside of the blades (6, 13) and then mounting on the ladder support assembly (19), the method according to claim 21.

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