Wind turbine blade

Abstract

A wind turbine blade includes upper and lower half-shells (12, 13) and first and second elongated webs (16, 17), the first and second elongated webs (16, 17) being disposed between and connected to the upper and lower half-shells (12, 13), wherein each web (16, 17) includes upper and lower flanges (22, 40) connecting the web (16, 17) to an inner layer of the half-shell (12, 13), and wherein the first and second webs (16, 17) are connected relative to the half-shells (12, 13) by first and second reinforcing structures ( The first reinforcement structure (31) supporting the single first web (16) includes at least one stack (32) consisting of a plurality of pultruded composite strips (33), and the second reinforcement structure (42) includes at least one stack consisting of a fiber layer (43) infused with resin (27) disposed between the outer and inner layers (25, 28) of the upper and lower shells (12, 13), or a composite strip (46) including at least one stack (45) which is integral part of the second web (17) and forms the flange (40).

Description

Technical Field

[0001] The present invention relates to a wind turbine blade having a generally hollow blade body comprising an upper and a lower half-shell and first and second elongated webs, each extending along the longitudinal direction of the blade and disposed between and connected to the upper and lower half-shells, wherein the second web is arranged closer to the trailing edge of the blade and extends only a portion of the trailing edge, wherein each web includes upper and lower flanges connecting the respective web to the respective half-shell, and wherein the first and second webs are supported relative to the respective half-shells via respective first and second reinforcing structures extending along the longitudinal direction of the blade. Background Technology

[0002] As is well known, wind turbine blades are part of a wind turbine used to generate electrical power. A wind turbine typically consists of three blades attached to a hub, which is connected to a generator housed in a nacelle. These blades interact with the passing wind, causing the hub to rotate, ultimately driving the generator.

[0003] Turbine blades typically comprise a hollow blade body with an upper half-shell and a lower half-shell, which are usually manufactured separately and attached to each other. First and second elongated webs are arranged within this hollow blade body, connecting and supporting the two half-shells while also transmitting loads acting on the respective shells due to aerodynamics and the circumferential motion of the blade during rotation. These loads include pressure and suction loads on the upper and lower half-shells, as well as compressive and tensile loads. For example, a wind turbine blade with this common configuration is disclosed in EP 2 791 500 B1.

[0004] To support the half-shell and to transfer the corresponding load, each elongated web extends longitudinally and is connected to the corresponding half-shell via flanges disposed on the respective web sides, the flanges being attached to the inner layers of the upper and lower half-shells by adhesive. To transfer the load or, consequently, to support the corresponding shell, each web is supported relative to the corresponding half-shell via corresponding first and second reinforcing structures. Such reinforcing structures are commonly referred to as spar caps. Like the corresponding webs and their flanges, these reinforcing structures or spar caps also extend longitudinally along the blade. As disclosed, for example, in EP 2 791 500 B1, these reinforcing structures are made from a stack comprising separate carbon fiber pultrusion strips arranged on top of each other and fixed in a resin matrix. During the manufacture of such pultrusion strips, carbon fibers are drawn through a supply of liquid resin, which is then heated and cured, ultimately forming the respective pultrusion strip. These pultruded carbon fiber strips exhibit excellent mechanical properties in bearing and distributing loads, and also absorb the high bending moments generated during blade rotation.

[0005] In known wind turbine blade designs, such as those disclosed in EP 2 791 500 B1, the blade includes two first webs that extend almost entirely along the length of the blade and are arranged in the central body region, i.e., in an area where the upper and lower half-shells are significantly apart when viewed in a teardrop cross-section. A second web is also provided, arranged near the trailing edge of the blade. This second web extends only along a portion of the trailing edge, which typically has a specific edge design and is subjected to specific loads, which are borne or distributed accordingly by the second web.

[0006] All webs comprise elongated web bodies with flanges disposed at the ends of the web bodies. Each web is supported by two reinforcing structures, namely spar caps, such that a total of six spar caps are arranged in two shells to support the three webs. Although the mass of the spar caps themselves is reduced in some way due to the use of carbon fiber pultruded stacks, the total mass of such known turbine blades is high due to the need to integrate three webs and six spar caps, and the carbon fiber pultruded stacks are expensive.

[0007] Therefore, an improved wind turbine blade design is needed to allow for adequate load support and a less complex and heavy design. Summary of the Invention

[0008] To address this issue, the wind turbine blades mentioned above are characterized in that the first reinforcing structure supporting a single first web includes at least one stacked member composed of a plurality of pultruded composite strips comprising carbon fibers, wherein these strips are fixed in a resin matrix, and a second reinforcing structure supporting the second web is also included.

[0009] - Includes at least one stacked member made of resin-infused glass and / or carbon fiber layers, the stacked member being disposed between the outer and inner layers of respective upper and lower shells, with a corresponding flange of the second web attached to the inner layer.

[0010] - Or it may include at least one stacked element consisting of a glass and / or carbon fiber layer infused with resin, or consisting of several pultruded composite strips comprising carbon fibers, wherein the strips are fixed in a resin matrix, the stacked element being an integral part of the second web and forming a corresponding flange attached to the inner layers of the corresponding upper and lower shells.

[0011] The first feature of the wind turbine blade of the present invention is that only one first web and only one second web are arranged in the hollow body. Unlike the prior art which uses two first webs, the turbine blade of the present invention uses only one first web that can be optimally positioned. Viewed in cross-section of the blade, it is centered at the point of maximum profile thickness, and thus centered in the region where the maximum load exists. Since only one web is arranged, only two spars are needed to support this single first web relative to the half-shell. This allows for a significant reduction in the overall mass of the blade. Furthermore, the amount of carbon fiber, or the corresponding number of carbon fiber pultruded strip stacks, is also reduced because only two spars or corresponding reinforcing structures are needed to support the first web, thereby reducing the overall cost of blade production. Finally, since only one first web is arranged, only two adhesives are needed to bond the web flange to the inner layer of the half-shell, which facilitates faster production and allows for easier repairs when needed.

[0012] Secondly, the turbine of the present invention is further characterized by a specific arrangement regarding the second web or the corresponding second reinforcing structure. In a first alternative, the second reinforcing structure supporting the second web comprises at least one stacked member consisting of resin-infused glass and / or carbon fiber layers. This stacked member is disposed between the outer and inner layers of the respective upper and lower shells in a region adjacent to the location where the flange of the second web is attached to the corresponding inner layer by adhesive. According to this alternative, the second reinforcing structure does not include any pultruded carbon fiber strips, but is made of stacked members of glass and / or carbon fiber layers or corresponding fibrous fabrics stacked on top of each other and infused with resin. Therefore, they are produced in a known manner, such as, for example, by also producing the inner and outer layers of the respective shells, which are made of several individual resin-infused fibrous layers or fabrics. Thus, the manufacture of these second reinforcing structures according to this alternative is simplified and carried out according to usual production procedures. If only fiberglass layers or fabrics are used, the production of these reinforcing structures can be integrated into the production of the corresponding half-shells, and the corresponding fiberglass and / or carbon fiber layers can be easily arranged in the corresponding shell mold along with other shell components, and can be resin-infused along with all other components. Therefore, it can be easily integrated into ordinary production routines.

[0013] In a second alternative, at least one stack forming the corresponding second reinforcing structure is composed of a resin-infused glass and / or carbon fiber layer, or of several pultruded composite strips comprising carbon fibers, wherein these strips are fixed in a resin matrix. In this embodiment, the corresponding second spar cap may be made of glass or carbon fiber fabric or of carbon fiber pultruded strips. Regardless of the material used to manufacture the corresponding reinforcing structure, the reinforcing structure is integral part of the second web and forms the corresponding flange, which is attached to the inner layer of the corresponding shell by means of an adhesive. The second web according to this embodiment has an H-shape, having a central web body and an integral flange attached to the web body. Since the web body comprises a resin matrix, the matrix also integrally extends into the corresponding flange or the corresponding stack, thereby making the H-shaped second web very rigid and a mechanically adaptable component. The web body may include a core, for example made of balsa wood, PET, or PVC, arranged in a resin-infused glass fiber sheath or shell. When producing the web, all the corresponding parts can be easily arranged in a common web mold by simply inserting the corresponding core and fiber layers or the corresponding fabric or pultruded strip, and by finally pouring the entire web set.

[0014] A particular advantage of this embodiment is that the H-shaped web can be manufactured outside the corresponding shell, thus already including the corresponding spar cap. This allows for simplified production of the spar cap and, in particular, allows for proper inspection of the connection between the web or the corresponding reinforcement structure, i.e., the connection between the spar cap and the web body. Furthermore, the adhesive bonding between the web flange, i.e., the spar cap, and the inner layers of the upper and lower shells needs to withstand relatively small loads, and the corresponding reinforcement structure or the corresponding spar cap is an integral part of the web.

[0015] Regardless of which of the two embodiments provides a second web configuration, the wind turbine blade of the present invention has an improved design superior to known blade designs. First, only a single first web is used, thus requiring only a single spar cap arranged in the upper and lower housings. While known turbine blades include two first webs with corresponding two spar caps in each housing, this can be referred to as a double-cap design, but the turbine blade of the present invention includes only a single spar cap supporting the first web, and is therefore referred to as a single-cap design. This simplifies production and reduces the use of expensive carbon fiber-based materials. Furthermore, the specific design of the second reinforcing structure is advantageous over known turbine blades because in the first alternative embodiment, the corresponding spar cap is produced in a known manner by providing a resin-infused stack of corresponding fiber fabrics, which simplifies overall production and avoids the use of expensive carbon fiber. In the second alternative embodiment, a specific H-shaped web design is used, which also allows for simplified production.

[0016] According to one embodiment of the invention, a first reinforcing structure is disposed between the outer and inner layers of the respective upper and lower shells. The stack of carbon fiber pultruded strips is an integral part of the respective shell and is sandwiched between the outer shell layer and the inner shell layer at a position adjacent to the position where the respective flange of the first web is attached to the inner surface of the inner layer.

[0017] Preferably, each first reinforcing structure comprises more than one stacked member arranged in parallel, preferably three stacked members arranged adjacent to each other. This allows the overall shape of the first reinforcing structure, i.e., the spar cap, to be formed along the slightly curved shape of the respective upper and lower shells, such that the respective spar cap closely conforms to the shell shape, and the distance between the upper and lower surfaces of the respective stacked members and the adjacent outer and inner layers is small. This avoids the need to increase the thickness of the outer or inner layers or to provide thicker resin areas in these regions. Therefore, the overall mass of the blade can be further reduced.

[0018] Furthermore, the first reinforcing structure may also include a biaxial glass and / or carbon fiber layer between each pair of strips, said layer being infused with resin. To bond these strips together, fiber layers or fiber fabrics are inserted between the respective strips of the stack. Thus, the entire stack has a sandwich arrangement in which pultruded strips are followed by fiber layers or fabrics, which in turn are followed by another strip, and so on. Inventively, the biaxial fiber layers are infused with resin, which forms the resin matrix into which the entire stack is embedded. The biaxial fiber layers comprise fibers arranged at an angle of 0° and other fibers arranged at angles of, for example, ±45°. Such biaxial layers are advantageous because they allow for the resistance to loads in different directions or correspondingly different types, such as loads caused by blade flapping or oscillating bending.

[0019] Since the pultruded stack is produced outside the corresponding half-shell, its design can be easily adapted to meet the specific needs by pouring the pultruded strip stack, arranged together with the biaxial layer in the mold, into the mold using the appropriate mold. Then, a prefabricated first reinforcing structure is arranged in the corresponding shell mold so that it is ultimately embedded in the appropriate resin during the final shell pouring.

[0020] Furthermore, the second reinforcing structure may also each include more than one stacked member arranged in parallel. When the second reinforcing structure is an integral part of the upper or lower shell, the two or, for example, three stacked members are constructed in a shell mold. In this case, corresponding individual glass and / or carbon fiber layers are stacked on top of each other layer by layer, and subsequently, resin is infused during the overall infusion of the corresponding shell half. Alternatively, in a second embodiment, the corresponding stacked member including a fabric layer is constructed in a corresponding structural mold and infused with resin for embedding the corresponding layer, and then the externally generated reinforcing structure is arranged in a corresponding shell mold for final embedding in the shell resin.

[0021] In another embodiment of the invention, the stacked glass and / or carbon fiber layers forming the second reinforcing structure are uniaxial layers. These layers consist only of parallel fibers extending along the longitudinal direction of the blade. Using uniaxial layers is advantageous for supporting loads caused by flapping bending. Uniaxial layers can be used if the corresponding second reinforcing structure is integrally arranged in the upper and lower shells, or when the second reinforcing structure is an integral part of the H-shaped second web itself.

[0022] As mentioned above, alternative embodiments of the second web configuration include a second reinforcing structure serving as an integral flange of the second web. If such an H-shaped second web is used, preferably, at least one core element is disposed adjacent to a corresponding integral second reinforcing structure attached to the inner layer of the second web between the inner and outer layers of the upper and lower half-shells. This core element is integrally integrated into the upper and lower half-shells to reinforce the corresponding shell in the region where the second web is arranged. The core supports the web joint achieved by an adhesive, and the corresponding reinforcing structure flange, i.e., the integral web spar cap, is attached by the adhesive to the inner surface of the inner layer of the half-shell. It provides better support and load transfer via the second web.

[0023] The core element can be made of various materials, such as balsa wood, polymers, or composites, which may also include resin-infused fiber layers or fabrics. Regardless of the material used, the core is an integral part of the corresponding shell and is sandwiched between the outer and inner layers. If a wood or polymer core element is used, the element is produced as a preform and then inserted into the corresponding shell mold, where the corresponding layers or elements for setting the corresponding half-shell are also inserted. It is fixed to the shell by resin. When using a core element made of a composite material such as a glass fiber layer, the corresponding laminate can be directly set in the shell mold and subsequently co-infused with resin during the overall shell infusion process.

[0024] As mentioned above, the corresponding reinforcing structures and core elements are used to support the corresponding webs or web joints. They reinforce the shell region to which the corresponding web flanges are attached adjacently, and are therefore an important part of load support or corresponding load distribution. It is therefore advantageous when the first and / or second reinforcing structures and / or core elements, which are integral parts of the corresponding shell, have a greater width than the corresponding adjacent flanges of the corresponding first and / or second webs. Viewed in a teardrop cross-section, the corresponding structure or core element is wider than the corresponding flange of the corresponding web. It extends along the side of the corresponding flange, which allows for better support and load distribution. Preferably, all reinforcing structures or corresponding core elements are wider than the corresponding web flanges.

[0025] To further adjust the mechanical properties of the blades in the region adjacent to the corresponding reinforcing structure or core element integrated into the respective half-shells, several additional core elements are disposed between the outer and inner layers of the respective upper and lower half-shells. These core elements may be made of, for example, foam, wood, or polymer, and this list is not exhaustive.

[0026] The present invention also relates to a wind turbine comprising a plurality of wind turbine blades as described above, preferably three turbine blades. Attached Figure Description

[0027] Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. However, the drawings are merely schematic diagrams designed for illustrative purposes only and do not limit the invention. The drawings show:

[0028] Figure 1 A simplified schematic diagram of a wind turbine.

[0029] Figure 2 A view of the wind turbine blade of the present invention, including the first and second webs.

[0030] Figure 3 : Along Line III-III Figure 2 A cross-sectional view of the blade.

[0031] Figure 4 : Figure 3 Enlarged view of section IV,

[0032] Figure 5 : Figure 3 An enlarged view of segment V.

[0033] Figure 6 A cross-sectional view of the wind turbine blade of the present invention according to the second embodiment, and...

[0034] Figure 7 : Figure 6 An enlarged view of section VII. Detailed Implementation

[0035] Figure 1 A schematic diagram of a wind turbine 1 is shown, which includes a tower 2, a nacelle 3 mounted on top of the tower 2, and a rotor 4. The rotor 4 includes three wind turbine blades 5 attached to a hub 6, which is operatively coupled to a generator arranged in the nacelle 3. The generator is driven by the rotational energy of the rotor 4 to generate electrical power as is generally known.

[0036] This invention relates to the arrangement of wind turbine blades 5.

[0037] Figure 2 A schematic diagram of a turbine blade 5 is shown, which has a root 7 for attaching the blade 5 to a hub and a tip 8 at the end of another blade. It also includes a leading edge 9 and a trailing edge 10.

[0038] See Figure 3The blade 5 includes a hollow blade body 11, which is made of an upper half-shell 12 and a lower half-shell 13, which are fixed to each other by an adhesive 14 and surround a hollow space 15. A first web 16 and a second web 17 are arranged in this space 15. The first web 16 is arranged almost centrally in the hollow space 15, at the location where the upper half 12 and the lower half 13 have the greatest distance or, correspondingly, where the blade has its maximum profile thickness. Figure 2 As shown, the ventral plate 16 extends almost the entire length of the leaf 5, starting adjacent to the root 7 and ending adjacent to the tip 8.

[0039] like Figure 2 As shown, the second web 17 is arranged near the trailing edge 10 and extends only over a portion of the blade length.

[0040] Both the first and second webs 16 and 17 are used to support the blade shells 12 and 13, and to bear and distribute the corresponding loads placed on the blades, which are caused by aerodynamic reasons due to the rotation of the rotor 4 and mechanical reasons due to the weight of the blades 5 themselves.

[0041] The first web 16 includes a web body 18, for example, see Figure 4 The web body 18 includes a core 19, which is made of, for example, balsa wood, stabilized foam, or composite materials, thereby exhibiting the mechanical properties required to reinforce the entire web 16. The core 19 is surrounded by one or more glass fiber layers 20, which are infused with resin, i.e., embedded in cured resin 21.

[0042] The web 16 also includes a flange 22, which is an integral part of the web 16 and integrally attached to the web body 18. The flange 18 also includes several layers 23, preferably glass fiber, i.e., glass fiber fabric, stacked on top of each other and also infused with resin and embedded in resin 21. The fiber stacks used to manufacture the respective flanges 22 may include biaxial and uniaxial fibers, but preferably, uniaxial fibers are used to reinforce the flanges to resist flapwise bending.

[0043] Each of the two flanges 22 of the first web 16 is attached to the inner surface of the upper half-shell 12 and the lower half-shell 13 by adhesive 24, see also Figure 4 .

[0044] Figure 4A cross-sectional view of a portion of the upper half-shell 12 is also shown, thus illustrating the corresponding shell arrangement, which is identical for the lower half-shell 13. Each shell 12, 13 includes an outer layer 25 comprising several layers of fiberglass or fabric 26, which are infused with resin, i.e., embedded in resin 27. The inner layer 28 of the shell 12 is configured to comprise several layers of fiberglass 29, which are also embedded in resin 27. The space between the outer and inner layers 25, 28 is filled with a core material 30, such as stabilizing foam or balsa wood, provided that no reinforcing structure is incorporated into the respective half-shell 12, 13 in this area.

[0045] Figure 4 It shows Figure 3 The enlarged section IV shows the first web 16 attached to the inner surface of the inner layer 28 of the upper housing 12. The same arrangement is achieved at the attachment section between the lower flange 22 and the lower housing 13. In this region, the first reinforcing structure 31, i.e., the first spar cap, is integrally inserted into the upper housing 12. The first reinforcing structure 31 comprises a total of three stacked members 32, arranged side-by-side and sandwiched between the outer layer 25 and the inner layer 28. Each stacked member 32 comprises a plurality of carbon fiber pultruded strips 33. These carbon fiber pultruded strips 33 comprise uniaxial carbon fibers drawn through a liquid resin supply device, which is then cured, such that the carbon fibers are firmly embedded in the corresponding resin forming the resin matrix. One or more biaxial glass fiber layers 34 are arranged between two adjacent carbon fiber pultruded strips 33, which are embedded in resin 35, such that they are infused with resin and thus fix the respective strips 33. Resin infusion can also surround the strip 33 along its sides, as well as its upper and lower surfaces. The corresponding stacked pieces 32 are constructed outside the corresponding housings 12, 13 and are inserted into the corresponding housing molds during housing production.

[0046] As from Figure 3 As can be seen, the first reinforcing structure extends wider than the corresponding flange 22, thus providing very good support for the flange 22. In this example, by using three separate stacked pieces 32, the overall curved shape of the respective housings 12, 13 can be closely followed, so that the respective stacked pieces 32 can be attached very tightly to the respective upper and lower layers 25, 28.

[0047] from Figure 3 It is evident that the corresponding shells 12 and 13 comprise only a single first reinforcing structure or a corresponding first spar cap 31, because only a single first web 16 is provided and it is centered in the region of maximum profile thickness.

[0048] Figure 5 It shows Figure 3A simplified diagram of the enlarged principle of section V, in which the second web 17 is attached to the upper housing 12. The same arrangement is also implemented at the attachment point of the web 17 and the lower housing 13.

[0049] The web 17 also includes a web body 36 having a core 37, i.e. a core 37 made of balsa wood or the like, which is surrounded in one or more glass fiber layers 38, which are embedded in resin 39, i.e. a resin matrix.

[0050] The second web 16 also includes two flanges 40, each composed of a plurality of uniaxial glass fiber layers 41, which are stacked on top of each other and embedded in resin 39 so that the flanges 40 are integral with the body 36. In addition, the second web 17 is also pre-constructed as a separate component, which is arranged in the corresponding shell mold when the shell is manufactured.

[0051] In addition, the flange 40 of the second web 17 is also attached to the inner surface of the inner layer 28 by an adhesive, the inner layer 28 comprising a glass fiber layer or fabric 29 embedded in resin 27.

[0052] To support the second web in each upper and lower shell 12, 13, a second reinforcing structure 42 is integrally arranged between the outer layer 25 and the inner layer 28. This second support structure, or the corresponding second spar cap 42, is constructed of several layers of glass and / or carbon fiber or fabric 43, which are resin-infused, i.e., embedded in resin 27, which is also embedded in the corresponding fiber layers 26 and 29 of the outer and inner layers 25, 28. During the production of the corresponding half-shells 12, 13, the corresponding glass and / or carbon fiber layers 43 are inserted as dry fibers into the corresponding shell mold, and subsequently, resin is infused together with the outer and inner layers 25, 28, i.e., all corresponding portions are subsequently injected into the corresponding resin 27, such that the corresponding second reinforcing structure 42 or the corresponding second spar cap 42 is an integral laminated construction or part of the corresponding half-shell 12, 13.

[0053] As in this embodiment, the turbine blade 5 includes only a single first web 16 and only a single second web 17, which extends only along a shorter length of the trailing edge, significantly reducing the overall weight of the blade. Because only one first web 16 is integrated, it can be positioned optimally for load distribution along the blade in both the longitudinal and transverse directions. Furthermore, each half-shell uses only one spar cap, allowing for further weight reduction, and the remainder of the cavity between the outer and inner layers can be filled with lightweight foam, etc. Additionally, using only one spar cap reduces the amount of carbon fiber used, which is quite expensive.

[0054] The second reinforcement structure 42 is arranged in a different manner compared to the first reinforcement structure 31, which allows for easy integration of these reinforcement structures 42, as they can be integrally constructed with the half-shell itself. This is because the corresponding fiber layers for manufacturing the reinforcement structure can be easily placed in the shell mold and injected into the corresponding resin along with all shell components.

[0055] Figure 6 and Figure 7 A second embodiment of the invention is shown in the figure. The same reference numerals are used for the same parts.

[0056] Figure 6 The turbine blade 5 shown also comprises only a single first web 16, which has a web body 18 and two integral flanges 22 fixed to the inner layers 28 of the upper and lower housings 12, 13. Between the inner layer 28 and the corresponding outer layer 25 of each housing 12, 13, a first reinforcing structure 31 based on carbon fiber pultruded strips, namely a first carbon fiber pultruded sparseal cap, is integrated. The blade arrangement in this blade section is the same as described with respect to the previous embodiments.

[0057] According to Figure 3-5 The blade 5 differs from the second web 17 in its arrangement. The second web 17 also includes a web body 36 and two flanges 40, which are also attached to the corresponding inner layers 28 of the upper and lower housings 12 and 13 by adhesive 44. This is consistent with the arrangement of the second web 17. Figure 5 The installation is similar.

[0058] In this embodiment, the design of the second web 17 differs from the design of the upper and lower half-shells 12 and 13 in the regions adjacent to the second web 17, such as... Figure 7 As shown in the image.

[0059] Figure 7 It shows Figure 6 Enlarged section VII shows a second web 17 having a web body 36 comprising a core 37 made of, for example, balsa wood, which is surrounded in a glass fiber structure comprising one or more glass fiber layers 38 infused with resin 39.

[0060] In this embodiment, the flange 40 is also the second reinforcing structure 42, which is an integral part of the web 17. In this embodiment, the flange 40 or the corresponding second reinforcing structure 42 is, for example, made of two stacks 45, each stack 45 consisting of a plurality of carbon fiber pultruded strips 46 comprising corresponding uniaxial carbon fibers embedded in a cured resin matrix. One or more biaxial glass fiber layers 47 are arranged between each pair of strips 46, and these biaxial glass fiber layers 47 are infused with resin 39 together with the corresponding stack 45. Thus, the resin 39 completely constitutes the entire resin matrix of the second web 17, and therefore, the second reinforcing structure 42 becomes an integral part of the second web 17. These second webs 17, having an integral reinforcing structure 42, i.e., an integral spar cap 42, are also manufactured separately as individual components. This allows for very good and precise manufacturing and inspection of the respective webs regarding their quality.

[0061] To reinforce the upper and lower shell 12 in the region adjacent to the second web 17 or the corresponding flange 40, the flange 40 is also attached to the inner layer 28 by means of an adhesive 44, and one or more core elements 48 are sandwiched between the outer layer 25 and the inner layer 28. These one or more core elements 48 may be made, for example, of wood, particularly balsa wood, particularly of stabilized foam, or of composite materials. In any case, the core element 48 has a higher density than, for example, the foam 30 surrounding it. Similarly, the width of this or these core elements 48 is wider than the width of the corresponding flange 40, i.e., the reinforcing structure or spar cap 42.

[0062] While the stack 45 includes carbon fiber pultruded strips 46 as explained, it is certainly possible that they may also include glass fiber pultruded strips to reinforce the corresponding flange structure.

[0063] Furthermore, this embodiment, which includes only a single first web 16, demonstrates the corresponding advantages arising from the use of this single first web 16, as already discussed regarding... Figure 3-5 As explained in the first embodiment.

[0064] Integrating the second reinforcing structure 42 into the integral flange portion of the second web 17 is also advantageous because, due to the integral arrangement of the second reinforcing structure 42 at the second web 17, the bonded joint between the corresponding reinforcing structure flange and the inner layer 28 of the half-shells 12, 13, achieved by the adhesive 44, bears less stress or load. Since the web 17 with the second reinforcing structure 42 is constructed as a separate component, optimal web configuration can be achieved, along with improved inspection possibilities regarding web quality. Furthermore, any repairs are easier to perform if necessary, because the reinforcing structure 42 is not an integral part of the corresponding shells 12, 13 and is therefore easily accessible.

[0065] Although the invention has been described in detail with reference to preferred embodiments, the invention is not limited to the disclosed examples, and other variations can be derived by those skilled in the art from the disclosed examples without departing from the scope of the invention.

Claims

1. A wind turbine blade having a generally hollow blade body (11), the blade body (11) comprising upper and lower half-shells (12, 13) and elongated first and second webs (16, 17), the first and second webs (16, 17) each extending along the longitudinal direction of the blade (5) and disposed between and connected to the upper and lower half-shells (12, 13), wherein the second web (17) is arranged closer to the blade (5). The trailing edge (10) of the blade (5) and extending only along a portion of the trailing edge (10), wherein each web (16, 17) includes upper and lower flanges (22, 40) connecting the respective web (16, 17) to the respective half-shell (12, 13), and wherein the first and second webs (16, 17) are supported relative to the respective half-shell (12, 13) via respective first and second reinforcing structures (42) extending along the longitudinal direction of the blade (5), characterized in that, The first reinforcement structure supporting a single first web (16) includes at least one stack consisting of a plurality of pultruded composite strips (33) comprising carbon fibers, wherein the strips (33) are fixed in a resin matrix and support a second reinforcement structure (42) supporting the second web (17). - Includes at least one stack consisting of separate glass and / or carbon fiber layers, the stack being disposed between the outer and inner layers (25, 28) of respective upper and lower half-shells (12, 13) and infused together with the outer and inner layers using resin, wherein the corresponding flange (40) of the second web (17) is attached to the inner layer (28). - Or it may include at least one stacked component consisting of a glass and / or carbon fiber layer infused with resin, or consisting of a plurality of pultruded composite strips comprising carbon fibers, wherein the strips are fixed in a resin matrix, the stacked component being an integral part of the second web (17) and forming a corresponding flange (40), wherein the second web (17) comprising the flange (40) is a prefabricated separate component, wherein its flange (40) is attached to the inner layer (28) of the corresponding upper and lower half-shells (12, 13).

2. The wind turbine blade according to claim 1, characterized in that, The first reinforcing structure is disposed between the outer and inner layers (25, 28) of the respective upper and lower half-shells (12, 13).

3. The wind turbine blade according to claim 1 or 2, characterized in that, Each of the first reinforcing structures includes further stacked components arranged in parallel.

4. The wind turbine blade according to claim 1 or 2, characterized in that, The first reinforcing structure includes a biaxial glass and / or carbon fiber layer between each pair of strips (33), the biaxial glass and / or carbon fiber layer being infused with resin.

5. The wind turbine blade according to claim 1 or 2, characterized in that, Each of the second reinforcement structures (42) includes more stacked elements arranged in parallel.

6. The wind turbine blade according to claim 1 or 2, characterized in that, The glass and / or carbon fiber layer of the second reinforcing structure is a uniaxial layer.

7. The wind turbine blade according to claim 1 or 2, characterized in that, At least one core element (48) is disposed adjacent to the corresponding integral second reinforcement structure (42) of the second web (17) attached to the inner layer (28) between the outer and inner layers (25, 28) of the upper and lower half-shells.

8. The wind turbine blade according to claim 7, characterized in that, The core element (48) is made of wood, polymer or composite material.

9. The wind turbine blade according to claim 7, characterized in that, Compared to the corresponding adjacent flanges (22, 40) of the corresponding first and / or second reinforcing structures (42) and / or the core element (48), the first reinforcing structure and / or the second reinforcing structure (42) and / or the core element (48) have a greater width.

10. The wind turbine blade according to claim 7, characterized in that, Multiple additional core elements (30) are disposed between the outer and inner layers (25, 28) of the respective upper and lower half-shells (12, 13).

11. The wind turbine blade according to claim 10, characterized in that, The additional core element (30) is made of foam, wood or polymer.

12. A wind turbine comprising a plurality of wind turbine blades (5) according to any one of claims 1-11.

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