HYBRID PULTRUSION PLATES FOR A SPAR CAP OF A WIND TURBINE BLADE

Abstract

The present invention relates to a method of manufacturing a wind turbine blade shell component (38), the method comprising the steps of providing a plurality of pultrusion plates (64), arranging the pultrusion plates (64) on blade shell material (89) in a mould (77) for the blade shell component, and bonding the pultrusion plates (64) with the blade shell material to form the blade shell component, wherein each pultrusion plate (64) is formed of a pultrusion fibre material comprising glass fibres and carbon fibres. The invention also relates to a reinforcing structure for a wind turbine blade, the reinforcing structure comprising a plurality of pultrusion plates according to the present invention.

Claims

1. A method of manufacturing a wind turbine blade shell component (38), the method comprising the steps of providing a plurality of pultrusion plates (64), arranging the pultrusion plates (64) on blade shell material (89) in a mould (77) for the blade shell component, and bonding the pultrusion plates (64) with the blade shell material to form the blade shell component, wherein each pultrusion plate (64) is formed of a pultrusion fibre material comprising glass fibres and carbon fibres.

2. A method according to claim 1, wherein the pultrusion fibre material comprises a plurality of tows of glass fibre material (70) and a plurality of tows of carbon fibre material (68).

3. A method according to claim 2, wherein the tows of glass fibre material (70) and the tows of carbon fibre material (68) are arranged in an array of rows (71) and columns (72) of tows, as seen in a vertical cross section of the pultrusion plate.

4. A method according to claims wherein each pultrusion plate (64) comprises a top surface (81), an opposing bottom surface (82) and two lateral surfaces (83, 84), wherein at least one continuous path (67a) of adjoining tows of carbon fibre material is provided within the pultrusion plate, the continuous path of adjoining tows of carbon fibre material extending from the top surface to the opposing bottom surface of the pultrusion plate.

5. A method according to any of claim 4, wherein the pultrusion plates are arranged into adjacent stacks of pultrusion plates, and wherein a continuous path (67) of adjoining tows of carbon fibre material extends from the top surface of the uppermost pultrusion plate to the bottom surface of the lowermost pultrusion plate of each stack of pultrusion plates.

6. A method according to claim 2, wherein a continuous path (67b) of adjoining tows of glass fibre material is provided along the lateral edges of the pultrusion plate, the continuous path of adjoining tows of glass fibre material extending from the top surface to the opposing bottom surface of the pultrusion plate.

7. A method according to claim 2, wherein the plurality of tows of glass fibre material and the plurality of tows of carbon fibre material form a non-random pattern, preferably a symmetrical pattern, as seen in a vertical cross section of the pultrusion plate.

8. A method according to claim 7, wherein the pattern comprises an I-shaped or a rectangular arrangement of tows of carbon fibre material among adjoining tows of glass fibre material.

9. A pultrusion plate (64) formed of a pultrusion fibre material comprising glass fibres and carbon fibres, wherein the pultrusion fibre material comprises a plurality of tows of glass fibre material (70) and a plurality of tows of carbon fibre material (68).

10. A pultrusion plate according to claim 9, wherein the tows of glass fibre material (70) and the tows of carbon fibre material (68) are arranged in an array of rows (71) and columns (72) of tows, as seen in a vertical cross section of the pultrusion plate.

11. A pultrusion plate according to claims wherein each pultrusion plate comprises a top surface (81), an opposing bottom surface (82) and two lateral surfaces (83, 84), wherein at least one continuous path (67a) of adjoining tows of carbon fibre material is provided within the pultrusion plate, the continuous path of adjoining tows of carbon fibre material extending from the top surface to the opposing bottom surface of the pultrusion plate.

12. A pultrusion plate according to claim 9, wherein a continuous path (67b) of adjoining tows of glass fibre material is provided along the lateral edges of the pultrusion plate, the continuous path of adjoining tows of glass fibre material extending from the top surface to the opposing bottom surface of the pultrusion plate.

13. A pultrusion plate according to claim 9, wherein the plurality of tows of glass fibre material and the plurality of tows of carbon fibre material form a non-random pattern, preferably a symmetrical pattern, as seen in a vertical cross section of the pultrusion plate.

14. A pultrusion plate according to claim 13, wherein the pattern comprises an I-shaped or a rectangular arrangement of tows of carbon fibre material among adjoining tows of glass fibre material.

15. A reinforcing structure for a wind turbine blade, the reinforcing structure comprising a plurality of pultrusion plates (64) according to claim 8.

Description

DESCRIPTION OF THE INVENTION

[0047] The invention is explained in detail below with reference to an embodiment shown in the drawings, in which

[0048] FIG. 1 shows a wind turbine,

[0049] FIG. 2 shows a schematic view of a wind turbine blade,

[0050] FIG. 3 shows a schematic view of a cross-section of a wind turbine blade,

[0051] FIG. 4 is a schematic top view of a shell half of a wind turbine blade according to the present invention,

[0052] FIG. 5 is a schematic vertical cross section through part of a shell half with a reinforcing structure of the present invention,

[0053] FIG. 6 illustrates a pultrusion process for manufacturing the pultrusion plates of the present invention,

[0054] FIG. 7 is a schematic vertical cross sectional view of different embodiments of the pultrusion plate of the present invention, and

[0055] FIG. 8 is a partial vertical cross sectional view of a reinforcing structure of the present invention, illustrating a possible misalignment of the pultrusion plates.

DETAILED DESCRIPTION OF THE FIGURES

[0056] FIG. 1 illustrates a conventional modern upwind wind turbine according to the so-called “Danish concept” with a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each having a blade root 16 nearest the hub and a blade tip 14 farthest from the hub 8. The rotor has a radius denoted R.

[0057] FIG. 2 shows a schematic view of a wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade and comprises a root region 30 closest to the hub, a profiled or an airfoil region 34 farthest away from the hub and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 comprises a leading edge 18 facing the direction of rotation of the blade 10, when the blade is mounted on the hub, and a trailing edge 20 facing the opposite direction of the leading edge 18.

[0058] The airfoil region 34 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 30 due to structural considerations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 10 to the hub. The diameter (or the chord) of the root region 30 may be constant along the entire root area 30. The transition region 32 has a transitional profile gradually changing from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 typically increases with increasing distance r from the hub. The airfoil region 34 has an airfoil profile with a chord extending between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with increasing distance r from the hub.

[0059] A shoulder 40 of the blade 10 is defined as the position, where the blade 10 has its largest chord length. The shoulder 40 is typically provided at the boundary between the transition region 32 and the airfoil region 34. FIG. 2 also illustrates the longitudinal extent L, length or longitudinal axis of the blade.

[0060] It should be noted that the chords of different sections of the blade normally do not lie in a common plane, since the blade may be twisted and/or curved (i.e. pre-bent), thus providing the chord plane with a correspondingly twisted and/or curved course, this being most often the case in order to compensate for the local velocity of the blade being dependent on the radius from the hub.

[0061] The blade is typically made from a pressure side shell part 36 and a suction side shell part 38 that are glued to each other along bond lines at the leading edge 18 and the trailing edge of the blade 20.

[0062] FIG. 3 shows a schematic view of a cross section of the blade along the line I-I shown in FIG. 2. As previously mentioned, the blade 10 comprises a pressure side shell part 36 and a suction side shell part 38. The pressure side shell part 36 comprises a spar cap 41, also called a main laminate, which constitutes a load bearing part of the pressure side shell part 36. The spar cap 41 comprises a plurality of fibre layers 42 mainly comprising unidirectional fibres aligned along the longitudinal direction of the blade in order to provide stiffness to the blade. The suction side shell part 38 also comprises a spar cap 45 comprising a plurality of fibre layers 46. The pressure side shell part 36 may also comprise a sandwich core material 43 typically made of balsawood or foamed polymer and sandwiched between a number of fibre-reinforced skin layers. The sandwich core material 43 is used to provide stiffness to the shell in order to ensure that the shell substantially maintains its aerodynamic profile during rotation of the blade. Similarly, the suction side shell part 38 may also comprise a sandwich core material 47.

[0063] The spar cap 41 of the pressure side shell part 36 and the spar cap 45 of the suction side shell part 38 are connected via a first shear web 50 and a second shear web 55. The shear webs 50, 55 are in the shown embodiment shaped as substantially I-shaped webs. The first shear web 50 comprises a shear web body and two web foot flanges. The shear web body comprises a sandwich core material 51, such as balsawood or foamed polymer, covered by a number of skin layers 52 made of a number of fibre layers. The blade shells 36, 38 may comprise further fibre-reinforcement at the leading edge and the trailing edge. Typically, the shell parts 36, 38 are bonded to each other via glue flanges.

[0064] FIG. 4 is a schematic top view of a shell half 38 of a wind turbine blade according to the present invention, illustrating the location of a reinforcing structure 62 having a spanwise extent Se. In the illustrated embodiment, the reinforcing structure 62 comprises three adjacent stacks 66a, 66b, 66c of pultrusion plates. As seen in FIG. 4, the elongate reinforcing structure 62 extends in a substantially spanwise direction of the blade, with adjacent stacks 66a, 66b, 66c of pultrusion plates. The elongate reinforcing structure 62 has a tip end 74, closest to the tip end of the blade, and a root end 76, closest to the root end of the blade. The elongate reinforcing structure also comprises a spanwise extending front edge 78, which is closest to the leading edge 18 of the blade, and a spanwise extending rear edge 80, which is closest to the trailing edge 20 of the blade.

[0065] FIG. 5 is a schematic vertical cross section through part of a shell half with a reinforcing structure 62 of the present invention, as seen from the root end of the blade. The reinforcing structure 62, such as a spar cap, comprises a plurality of pultrusion plates 64 according to the present invention, arranged in adjacent stacks 66a-e, which are arranged on blade shell material 89 in mould 77 for the blade shell component, such as a shell half. The stacked pultrusion plates 64 are then bonded with the blade shell material 89 to form the blade shell component, such as the shell half with the spar cap. Core material 85 is arranged on either chordwise side of the reinforcing structure 62. A first shear web 50 and a second shear web 55 is placed on the spar cap 62 via respective bond lines 88. The stacks 66a-e may be covered by a carbon biax layer 86 or a carbon veil or a glass/carbon hybrid fabric or a glass/carbon hybrid veil extending towards current connection terminal 87 of a lightning protection system.

[0066] FIG. 6 illustrates a pultrusion process for manufacturing the pultrusion plates 64 of the present invention. The pultrusion process makes use of a pultrusion system 90 which comprises a portion for receiving a plurality of bobbins 92 each supplying a tow of glass fibre material 70 and a plurality of bobbins 93 each supply a tow of carbon fibre material 68 from a creel 91. Additional reinforcement material 94 may be provided. The tows 68, 70 are pulled through guide plates 95, resin bath 96, and heated die 97 by pulling mechanism 98. The pultrusion string 100 is cut into individual pultrusion plates 64 by cutter 99. The shaped impregnated fibres are cured and can optionally be wound onto a roll. The guide plates and/or the die may take the form of a spreader or inlet comprising multiple apertures, each aperture receiving a respective carbon fibre tow or glass fibre two. The apertures can be spaced and they are located so as to guide the fibre tows to form a desired pattern of glass fibre tows and carbon fibre tows in the pultrusion plates 64. The enlarged view of the pultrusion plate 64 in FIG. 6 also illustrates its longitudinal axis La and its length l. The height/thickness h and width w of the pultrusion plate are illustrated in FIG. 8, see plate 64f.

[0067] Various of the patterns of the present invention are illustrated in FIG. 7, which is a schematic vertical cross sectional view of different embodiments of the pultrusion plate 64 of the present invention, taken along the line a-a′ in FIG. 6. Each pultrusion plate 64 in the various embodiments illustrated in FIGS. 7a-j comprises a plurality of tows of glass fibre material 70, indicated as white elliptical shapes, and a plurality of tows of carbon fibre material 68, indicated as black elliptical shapes. As illustrated in FIG. 7a, the tows of glass fibre material 70 and the tows of carbon fibre material 68 are arranged in an array of rows 71 and columns 72 of tows, as seen in a vertical cross section of the pultrusion plate.

[0068] As illustrated in FIG. 7a, each pultrusion plate comprises a top surface 81, an opposing bottom surface 82 and two lateral surfaces 83, 84, wherein preferably at least one continuous path 67a of adjoining tows of carbon fibre material is provided within the pultrusion plate 64; see FIG. 7f. The continuous path 67a of adjoining tows of carbon fibre material extends from the top surface 81 to the opposing bottom surface 82 of the pultrusion plate 64. In some embodiments, as shown in the checkerboard pattern of FIG. 7a, said path of adjoining tows of carbon fibre may be a diagonal path extending from the top surface 81 to the opposing bottom surface 82 of the pultrusion plate. Also, in some embodiments, a continuous path 67b of adjoining tows of glass fibre material is provided along the lateral edges 83, 84 of the pultrusion plate 64, the continuous path 67b of adjoining tows of glass fibre material extending from the top surface 81 to the opposing bottom surface 82 of the pultrusion plate; as exemplified in FIG. 7f.

[0069] As seen in the various embodiments of FIG. 7, the plurality of tows of glass fibre material 70 and the plurality of tows of carbon fibre material 68 form a non-random pattern, preferably a symmetrical pattern, as seen in a vertical cross section of the pultrusion plate 64. FIG. 7a illustrates a checkerboard pattern, FIG. 7b illustrates a pattern with two vertical lines of tows of carbon fibre material surrounded by tows of glass fibre material, and FIGS. 7c and d illustrated various uniform rows of glass fibre tows on top of various uniform rows of carbon fibre tows, and vice versa. FIG. 7e illustrates a pattern that comprises two adjacent I-shaped arrangements of tows of carbon fibre material surrounded by tows of glass fibre material, whereas FIG. 7f-j show different patterns with rectangular arrangements of carbon fibre tows.

[0070] FIG. 8 is a schematic vertical cross sectional view of a reinforcing structure of the present invention, such as a spar cap comprising two chordwise adjacent stacks 66a and 66b of pultrusion plates 64a-f. FIG. 8 also illustrates a possible misalignment of the pultrusion plates 64a-f. Despite the misalignment caused by relative chordwise movement of the pultrusion plates, a continuous path 67 of adjoining tows of carbon fibre material 68 extends from the top surface 81 of the uppermost pultrusion plate 64a to the bottom surface 82 of the lowermost pultrusion plate 64c of each stack of pultrusion plates due to the pattern of tows of carbon fibre material and tows of glass fibre material.

[0071] The invention is not limited to the embodiments described herein and may be modified or adapted without departing from the scope of the present invention.

LIST OF REFERENCE NUMERALS

[0072] 4 tower [0073] 6 nacelle [0074] 8 hub [0075] 10 blades [0076] 14 blade tip [0077] 16 blade root [0078] 18 leading edge [0079] 20 trailing edge [0080] 30 root region [0081] 32 transition region [0082] 34 airfoil region [0083] 36 pressure side shell part [0084] 38 suction side shell part [0085] 40 shoulder [0086] 41 spar cap [0087] 42 fibre layers [0088] 43 sandwich core material [0089] 45 spar cap [0090] 46 fibre layers [0091] 47 sandwich core material [0092] 50 first shear web [0093] 51 core member [0094] 52 skin layers [0095] 55 second shear web [0096] 56 sandwich core material of second shear web [0097] 57 skin layers of second shear web [0098] 60 filler ropes [0099] 62 reinforcing structure [0100] 64 pultrusion plate [0101] 66 stack of pultrusion plates [0102] 67 path [0103] 68 tow of carbon fibre material [0104] 70 tow of glass fibre material [0105] 71 row of tows [0106] 72 column of tows [0107] 74 tip end of reinforcing structure [0108] 76 root end of reinforcing structure [0109] 77 mould [0110] 78 front edge of reinforcing structure [0111] 80 rear edge of reinforcing structure [0112] 81 top surface of pultrusion plate [0113] 82 bottom surface of pultrusion plate [0114] 83 first lateral surface of pultrusion plate [0115] 84 second lateral surface of pultrusion plate [0116] 85 core material [0117] 86 carbon biax layer [0118] 87 current connection terminal [0119] 88 bond line [0120] 89 shell material [0121] 90 pultrusion system [0122] 91 creel [0123] 92 bobbin with tow of glass fibre material [0124] 93 bobbin with tow of carbon fibre material [0125] 94 additional reinforcement material [0126] 95 guide plate [0127] 96 resin bath [0128] 97 heated die [0129] 98 pulling mechanism [0130] 99 cutter [0131] 100 pultrusion string [0132] L length [0133] l length of pultrusion plate [0134] w width of pultrusion plate [0135] h height of pultrusion plate [0136] La longitudinal axis of pultrusion plate [0137] r distance from hub [0138] R rotor radius [0139] Se spanwise extent of reinforcing structure [0140] Ce chordwise extent of reinforcing structure