Scarf connection for a wind turbine rotor blade

Abstract

A rotor blade for a wind turbine includes at least one blade segment defining an airfoil surface and an internal support structure. The internal support structure is formed, at least in part, of a first portion constructed of a first composite material and a second portion constructed of a different, second composite material, the second composite material arranged in a plurality of layers. The first and second portions are connected together via a scarf joint. Each of the plurality of layers of the second composite material includes an end that terminates at the scarf joint. The scarf joint includes a different, third composite material arranged between the first and second composite materials. The third composite material includes a plurality of segments, each of which is arranged so as to completely wrap the ends of the plurality of layers of the second composite material.

Claims

1. A rotor blade for a wind turbine, comprising: at least one blade segment defining an airfoil surface and comprising an internal support structure, wherein the internal support structure is formed, at least in part, of a first portion constructed of a first composite material and a second portion constructed of a second composite material being different than the first composite material, the second composite material arranged in a plurality of pultruded plates, the first and second portions connected together via a scarf joint, each of the plurality of pultruded plates of the second composite material comprising an end that terminates at the scarf joint, the scarf joint comprising a third composite material different than the first and second composite materials and arranged between the first and second composite materials, the third composite material comprising a plurality of segments, the plurality of segments arranged so as to completely wrap the ends of the plurality of pultruded plates of the second composite material.

2. The rotor blade of claim 1, wherein the third composite material further comprises a plurality of layers, wherein one or more of the plurality of layers of the third composite material extends between one or more of the pultruded plates.

3. The rotor blade of claim 2, wherein each of the plurality of segments of the third composite material is spaced apart from each of the plurality of layers of the third composite material.

4. The rotor blade of claim 2, wherein each of the plurality of layers of the third composite material terminates before respective ends of the pultruded plates of the second composite material.

5. The rotor blade of claim 1, wherein each of the plurality of segments of the third composite material comprise at least one of a C-shape, a V-shape, a U-shape, or an L-shape that wraps at least partially around one of the ends of the plurality of layers of the second composite material.

6. The rotor blade of claim 5, wherein each of the plurality of segments of the third composite material comprises the L-shape, wherein adjacent L-shaped segments are secured together in an opposing direction so as to wrap around the ends of adjacent layers of the plurality of layers of the second composite material.

7. The rotor blade of claim 1, wherein adjacent segments of the plurality of segments of the third composite material contact each other.

8. The rotor blade of claim 1, wherein the first, second, and third composite materials comprise at least one of a thermoset resin or a thermoplastic resin.

9. The rotor blade of claim 8, wherein at least one of the first composite material, the second composite material, and/or the third composite material is reinforced with one or more fiber materials.

10. The rotor blade of claim 9, wherein the one or more fiber materials comprise at least one of glass fibers, carbon fibers, polymer fibers, wood fibers, bamboo fibers, ceramic fibers, nanofibers, metal fibers, or combinations thereof.

11. The rotor blade of claim 8, wherein the third composite material comprises at least one of a composite veil material, a biax composite material, or a chopped strand mat.

12. A method of joining first and second structures of a rotor blade of a wind turbine, the method comprising: arranging the first structure with the second structure at a scarf joint, the first structure constructed of a first composite material, the second structure constructed of a second composite material being different than the first composite material, the second structure comprising a plurality of layers, each of the plurality of layers of the second composite material comprising an end that terminates at the scarf joint; arranging a plurality of segments of a third composite material that is different than the first and second composite materials between the first and second composite materials at the scarf joint so as to completely wrap the ends of the plurality of layers of the second composite material with the plurality of segments of the third composite material, wherein the third composite material comprises at least one of a composite veil material, a biax composite material, or a chopped strand mat; and, infusing the scarf joint so as to join the first and second structures together.

13. The method of claim 12, further comprising forming the plurality of layers of the second structure of a plurality of pultruded plates, the plurality of pultruded plates formed of the second composite material.

14. The method of claim 13, wherein the third composite material further comprises a plurality of layers, wherein one or more of the plurality of layers of the third composite material extends between one or more of the plurality of pultruded plates.

15. The method of claim 14, wherein each of the plurality of segments of the third composite material is spaced apart from each of the plurality of layers of the third composite material.

16. The method of claim 14, wherein each of the plurality of layers of the third composite material terminates before respective ends of the plurality of pultruded plates of the second composite material.

17. The method of claim 12, wherein each of the plurality of segments of the third composite material comprise at least one of a C-shape, a V-shape, a U-shape, or an L-shape that wraps at least partially around one of the ends of the plurality of layers of the second composite material.

18. The method of claim 17, wherein each of the plurality of segments of the third composite material comprises the L-shape, the method further comprising: securing adjacent L-shaped segments together in an opposing direction; and, arranging the secured L-shaped segments so as to wrap around the ends of adjacent layers of the plurality of layers of the second composite material.

19. The method of claim 12, further comprising arranging adjacent segments of the plurality of segments of the third composite material so as to contact each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

(2) FIG. 1 illustrates a perspective view of one embodiment of a wind turbine according to the present disclosure;

(3) FIG. 2 illustrates a plan view of one embodiment of a rotor blade having a first blade segment and a second blade segment according to the present disclosure, particularly illustrating example locations of a scarf joint;

(4) FIG. 3 illustrates a perspective view of a section of one embodiment of the first blade segment according to the present disclosure;

(5) FIG. 4 illustrates a perspective view of one embodiment of a section of the second blade segment at the chord-wise joint according to the present disclosure;

(6) FIG. 5 illustrates an assembly of one embodiment of the rotor blade of the wind turbine having the first blade segment joined with the second blade segment according to the present disclosure;

(7) FIG. 6 illustrates an exploded perspective view of one embodiment of the multiple supporting structures of the assembly of the rotor blade of the wind turbine according to the present disclosure;

(8) FIG. 7 illustrates a detailed, plan view of one embodiment of a scarf joint between one or more spar structures of the rotor blade and a blade segment of the rotor blade according to the present disclosure;

(9) FIG. 8 illustrates a detailed, plan view of the scarf joint of FIG. 7;

(10) FIG. 9 illustrates a detailed, plan view of another embodiment of a scarf joint between one or more spar structures of the rotor blade and a blade segment of the rotor blade according to the present disclosure; and

(11) FIG. 10 illustrates a flow chart of one embodiment of a method of joining a pultruded structure of a rotor blade of a wind turbine to a composite structure of the rotor blade according to the present disclosure.

DETAILED DESCRIPTION

(12) Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

(13) Referring now to the drawings, FIG. 1 illustrates a perspective view of one embodiment of a wind turbine 10 according to the present invention. In the illustrated embodiment, the wind turbine 10 is a horizontal-axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In addition, as shown, the wind turbine 10 may include a tower 12 that extends from a support surface 14, a nacelle 16 mounted on the tower 12, a generator 18 positioned within the nacelle 16, a gearbox 20 coupled to the generator 18, and a rotor 22 that is rotationally coupled to the gearbox 20 with a rotor shaft 24. Further, as shown, the rotor 22 includes a rotatable hub 26 and at least one rotor blade 28 coupled to and extending outward from the rotatable hub 26. As shown, the rotor blade 28 includes a blade tip 17 and a blade root 19.

(14) Referring now to FIG. 2, a plan view of one of the rotor blades 28 of FIG. 1 is illustrated. As shown, the rotor blade 28 may include a first blade segment 30 and a second blade segment 32. Further, as shown, the first blade segment 30 and the second blade segment 32 may each extend in opposite directions from a chord-wise joint 34. In addition, as shown, each of the blade segments 30, 32 may include at least one shell member defining an airfoil surface. The first blade segment 30 and the second blade segment 32 are connected by at least an internal support structure 36 extending into both blade segments 30, 32 to facilitate joining of the blade segments 30, 32. The arrow 38 shows that the segmented rotor blade 28 in the illustrated example includes two blade segments 30, 32 and that these blade segments 30, 32 are joined by inserting the internal support structure 36 into the second blade segment 32. In addition, as shown, the second blade segment includes multiple spar structures 66 (also referred to herein as spar caps) that extend lengthwise for connecting with a blade root section 35 of the rotor blade 28 and with the first blade segment 30. In addition, as shown, the first blade segment 30 may also include one or more scarf joints 90 at an interface of one or more pultrusions (e.g. pultruded components or plates) and a composite structure as discussed in more detail with respect to FIGS. 7 and 8.

(15) Referring now to FIG. 3, a perspective view of a section of the first blade segment 30 according to the present disclosure is illustrated. As shown, the first blade segment 30 includes a beam structure 40 that forms a portion of the internal support structure 36 and extends lengthwise for structurally connecting with the second blade segment 32. Further, as shown, the beam structure 40 forms a part of the first blade segment 30 having an extension protruding from a spar section 42, thereby forming an extending spar section. The beam structure 40 includes a shear web 44 connected with a suction side spar cap 46 and a pressure side spar cap 48. As such, the scarf joints 90 described herein may be part of the beam structure 40.

(16) Moreover, as shown, the first blade segment 30 may include one or more first pin joints towards a first end 54 of the beam structure 40. In one embodiment, the pin joint may include a pin that is in a tight interference fit with a bushing. More specifically, as shown, the pin joint(s) may include one pin joint tube 52 located on the beam structure 40. Thus, as shown, the pin joint tube 52 may be oriented in a span-wise direction. Further, the first blade segment 30 may also include a pin joint slot 50 located on the beam structure 40 proximate to the chord-wise joint 34. Moreover, as shown, the pin joint slot 50 may be oriented in a chord-wise direction. In one example, there may be a bushing within the pin joint slot 50 arranged in a tight interference fit with a pin joint tube or pin (shown as pin 53 in FIG. 6). Further, the first blade segment 30 may include multiple second pin joint tubes 56, 58 located at the chord-wise joint 34. Thus, as shown, the second pin joint tubes 56, 58 may include a leading edge pin joint tube 56 and a trailing edge pin joint tube 58. Further, each of the second pin joint tubes 56, 58 may be oriented in a span-wise direction. In addition, as shown, each of the second pin joint tubes 56, 58 may include multiple flanges 55, 57, respectively, that are configured to distribute compression loads at the chord-wise joint 34.

(17) It is to be noted that the pin joint tube 52 located at the first end of the beam structure 40 may be separated span-wise with the multiple second pin joint tubes 56, 58 located at the chord-wise joint 34 by an optimal distance D. This optimal distance D may be such that the chord-wise joint 34 is able to withstand substantial bending moments caused due to shear loads acting on the chord-wise joint 34. In another embodiment, each of the pin joints connecting the first and second blade segments 30, 32 may include an interference-fit steel bushed joint.

(18) Referring now to FIG. 4, a perspective view of a section of the second blade segment 32 at the chord-wise joint 34 according to the present disclosure is illustrated. As shown, the second blade segment 32 includes a receiving section 60 extending lengthwise within the second blade segment 32 for receiving the beam structure 40 of the first blade segment 30. The receiving section 60 includes the spar structures 66 that extend lengthwise for connecting with the beam structure 40 of the first blade segment 30. As shown, the second blade segment 32 may further include pin joint slots 62, 64 for receiving pin joint tubes 56, 58 (shown in FIG. 3) of the first blade segment 30 and forming tight interference fittings. In one example, each of the multiple pin joint slots 62, 64 may include multiple flanges 61, 63, respectively, that are configured to distribute compression loads at the chord-wise joint 34.

(19) Referring now to FIG. 5, an assembly 70 of the rotor blade 28 having the first blade segment 30 joined with the second blade segment 32 according to the present disclosure is illustrated. As shown, the assembly 70 illustrates multiple supporting structures beneath outer shell members of the rotor blade 28 having the first blade segment 30 joined with the second blade segment 32. Further, as shown, the receiving section 60 includes the multiple spar structures 66 extending lengthwise and supports the beam structure 40. The receiving section 60 also includes a rectangular fastening element 72 that connects with the pin joint tube 52 of the beam structure 40 in the span-wise direction. Further, the first and the second blade segments 30, 32 may also include chord-wise members 74, 76 respectively at the chord-wise joint 34. Further, as shown, the chord-wise members 74, 76 may include leading edge pin openings 78 and trailing edge pin openings 80 that allows pin joint connections between the first and second blade segments 30, 32. For example, as shown, the chord-wise members 74, 76 are connected by pin joint tubes 56 and 58 that are in tight interference fit with bushings located in the leading edge pin openings 78 and the trailing edge pin openings 80. In another embodiment, each of the spar structures 66, the rectangular fastening element 72, and the chord-wise members 74, 76 may be constructed of glass reinforced fibers. In this example, the assembly 70 may also include multiple lightening receptor cables 73 that are embedded between the multiple pin joint tubes or pins 56, 58 and the bushing connections attached to the chord-wise members 74, 76.

(20) Referring now to FIG. 6, an exploded perspective view of the multiple supporting structures of the assembly 70 towards the receiving section 60 of the rotor blade 28 is illustrated. As shown, a pair of spar structures 66 is configured to receive the beam structure 40 and includes pin joint slots 82, 84 that are aligned with the pin joint slot 50 of the beam structure 40 through which a pin joint tube or pin 53 may be inserted. Further, the pin 53 is configured to remain in a tight interference fit within the aligning pin joint slots 82, 50, 84 such that spar structures 66 and the beam structure 40 are joined together by during assembling. Further, FIG. 6 also illustrates the rectangular fastening element 72 that includes a pin joint slot 86 configured for receiving the pin joint tube 52 of the beam structure 40. As such, the pin joint tube 52 is configured to form a tight interference fit bolted joint. Further, the pair of spar structures 66 may be joined together at one end 88 using any suitable adhesive material or an elastomeric seal.

(21) Referring to FIGS. 7 and 8, detailed plan views of one embodiment of the connection between one or more pultruded parts 95 and an adjacent composite structure of the first blade segment 30 of the rotor blade 28 of FIG. 2 are illustrated. As shown, the connection is a scarf joint 90. Further, as shown particularly in FIG. 2, the first blade segment 30 may include at least two scarf joints 90. In addition, as shown, a first portion 89 or end of the first blade segment 30 (e.g. the portion of the beam structure 40 adjacent to the pin joint tube 52 of the receiving end 54) may be constructed of a first composite material 92, whereas a second portion 91 of the first blade segment 30 may be constructed of a different, second composite material 94. Thus, as shown, the scarf joint 90 may further include a different, third composite material 96 arranged between the first and second composite materials 92, 94.

(22) More specifically, as shown in the illustrated embodiment, the second portion 91 of the first blade segment 30 may be constructed, at least in part, of a plurality of layers 95 formed of the second composite material 94. For example, in one embodiment, the plurality of layers 95 may be a plurality of pultruded plates. Thus, as shown, each of the pultruded plates 95 may be formed of the second composite material 94. In addition, as shown, each of the layers 95 may have an end 98 that terminates at the scarf joint 90. Further, as shown, the third composite material 96 may include a plurality of segments 99. More specifically, as shown, each of the segments 99 may be arranged so as to completely wrap the ends 98 of the layers 95 of the second composite material 94. Thus, as shown, in an embodiment, adjacent segments 99 of the third composite material 96 may contact each other.

(23) Still referring to FIGS. 7 and 8, the third composite material 96 may also include a plurality of layers 97 arranged between each of the pultruded plates 95. In such embodiments, as shown, one or more of the layers 97 of the third composite material 96 may extend between one or more of the pultruded plates 95. Further, in an embodiment, as shown, each of the plurality of layers 97 of the third composite material 96 may terminate before respective ends 98 of the pultruded plates 95 of the second composite material 94.

(24) Thus, as shown particularly in FIG. 8, each of the plurality of segments 99 of the third composite material 96 may be spaced apart from each of the layers 97 of the third composite material 96 such that there is a gap 85 therebetween.

(25) In addition, each of the segments 99 of the third composite material 96 may have any suitable shape, including but limited to, a C-shape, a V-shape, a U-shape, or an L-shape that wraps at least partially around one of the ends 98 of the layers 95 of the second composite material 94. For example, as shown in FIG. 7, the segments 99 have a C-shape. In another embodiment, as shown in FIG. 8, the segments 99 have a V-shape. Thus, in an embodiment, by providing such shapes of the third composite material 96 at the ends 98 of pultruded plates 95, the pultruded plates 95 are completely covered, without requiring the interleaving layers 97 of the third composite material 96 to extend past the ends 98 of the pultruded plates 95. This results in better resin infusion between the pultruded plates 95 and therefore increases joint strength. It should also be understood that the composite material forming the segments 99 may be the same as the interleaving layer material. However, it should also be understood that the composite material forming the segments 99 may be a different material than the interleaving layer material.

(26) In alternative embodiments, the segments 99 of the third composite material 96 may be provided in a split fashion. For example, as shown in FIG. 9, the segments 99 of the third composite material 96 may include the L-shape. In such embodiments, as shown, adjacent L-shaped segments 99 may be secured together (e.g. via adhesive, resin, tape, etc.) in an opposing direction so as to wrap around the ends 98 of adjacent layers 95 of the second composite material 94. More specifically, in one embodiment, in order to provide the third composite material 96 at the ends 98 in a split fashion, two interleaving L-shaped fabrics can be joined with adhesive and then can be peeled at the ends to join one piece of the third composite material 96 with another at the ends. In such embodiments, care should be taken that the thickness of the interleaving composite material 97 and the combined thickness of the two joined segments 99 in between the pultruded plates 95 are equal. Such an embodiment assists in maintaining uniform thickness between the interleaving composite material 97 and two joined segments 99 that are in between the pultruded plates 95.

(27) Thus, as shown, the pultruded plates 95 are completely covered at their ends 98 by the joined segments 99, while the interleaving composite material 97 does not extend past the pultruded plates 95. This results in better resin infusion between pultrusions and/or increases joint strength.

(28) In further embodiments, the first, second, and third composite materials 92, 94, 96 may include a thermoset resin or a thermoplastic resin. The thermoplastic materials as described herein may generally encompass a plastic material or polymer that is reversible in nature. For example, thermoplastic materials typically become pliable or moldable when heated to a certain temperature and returns to a more rigid state upon cooling. Further, thermoplastic materials may include amorphous thermoplastic materials and/or semi-crystalline thermoplastic materials. For example, some amorphous thermoplastic materials may generally include, but are not limited to, styrenes, vinyls, cellulosics, polyesters, acrylics, polysulphones, and/or imides. More specifically, exemplary amorphous thermoplastic materials may include polystyrene, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), glycolised polyethylene terephthalate (PET-G), polycarbonate, polyvinyl acetate, amorphous polyamide, polyvinyl chlorides (PVC), polyvinylidene chloride, polyurethane, or any other suitable amorphous thermoplastic material. In addition, exemplary semi-crystalline thermoplastic materials may generally include, but are not limited to polyolefins, polyamides, fluropolymer, ethyl-methyl acrylate, polyesters, polycarbonates, and/or acetals. More specifically, exemplary semi-crystalline thermoplastic materials may include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene, polyphenyl sulfide, polyethylene, polyamide (nylon), polyetherketone, or any other suitable semi-crystalline thermoplastic material.

(29) Further, the thermoset materials as described herein may generally encompass a plastic material or polymer that is non-reversible in nature. For example, thermoset materials, once cured, cannot be easily remolded or returned to a liquid state. As such, after initial forming, thermoset materials are generally resistant to heat, corrosion, and/or creep. Example thermoset materials may generally include, but are not limited to, some polyesters, some polyurethanes, esters, epoxies, or any other suitable thermoset material.

(30) In addition, the first, second, and/or third material 92, 94, 96 may be reinforced with one or more fiber materials. In such embodiments, the fiber material(s) may include glass fibers, carbon fibers, polymer fibers, wood fibers, bamboo fibers, ceramic fibers, nanofibers, metal fibers, or combinations thereof. In addition, the direction or orientation of the fibers may include quasi-isotropic, multi-axial, unidirectional, biaxial, triaxial, or any other another suitable direction and/or combinations thereof. Thus, in certain embodiments, the third composite material 96 may include, for example, a composite veil material, a biax composite material, or a chopped strand mat.

(31) Referring now to FIG. 10, a flow chart 100 of a method 100 of joining first and second structures (such as first and second portions of the beam structure 40) of a rotor blade of a wind turbine according to the present disclosure is illustrated. In general, the method 100 will be described herein with reference to the wind turbine 10 and the rotor blade 28 shown in FIGS. 1-9. However, it should be appreciated that the disclosed method 100 may be implemented with rotor blades having any other suitable configurations. In addition, although FIG. 10 depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure.

(32) As shown at (102), the method 100 may include arranging the first structure with the second structure at a scarf joint. The first structure is constructed of a first composite material. The second structure is constructed of a different, second composite material. The second structure also includes a plurality of layers, each of which includes an end that terminates at the scarf joint. As shown at (104), the method 100 may include arranging a plurality of segments of a different, third composite material between the first and second composite materials at the scarf joint so as to completely wrap the ends of the plurality of layers of the second composite material with the plurality of segments of the third composite material. As shown at (106), the method 100 may include infusing the scarf joint so as to join the first and second structures together.

(33) The skilled artisan will recognize the interchangeability of various features from different embodiments. Similarly, the various method steps and features described, as well as other known equivalents for each such methods and feature, can be mixed and matched by one of ordinary skill in this art to construct additional systems and techniques in accordance with principles of this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

(34) While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

(35) This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.