MANUFACTURING OF SEGMENTED WIND TURBINE BLADE

Abstract

The present invention relates to a method of manufacturing a wind turbine blade comprising the steps of manufacturing a pressure shell halves and arranging a spar structure (62) within one of the shell halves. The spar structure (62) comprises two parts releasably coupled to each other. The method results in a segmented wind turbine blade for easy transportation and re-assembly.

Claims

1. A spar structure (62) for a wind turbine blade, the spar structure comprising a first part (64) and a second part (66), the first and second part (66) being releasably coupled to each other, wherein the second part (66) of the spar structure (62) comprises a spar member (67), such as a spar beam or a spar box, the spar box comprising at least one spar beam and at least one spar flange, and wherein the first part (64) of the spar structure (62) comprises a sheath member for at least partly enclosing the second part (66) of the spar structure (62).

2. The spar structure (62) according to claim 1, wherein the sheath member is a conductive sheath member for a lightning protection system of a wind turbine blade.

3. The spar structure (62) according to claim 1, wherein the spar structure (62) comprises at least one locking pin (74) for releasably coupling the first part (64) to the second part (66) of the spar structure (62) through aligned respective locking apertures in each of the first and second part (66) of the spar structure (62).

Description

DESCRIPTION OF THE INVENTION

[0060] The invention is explained in detail below with reference to an embodiment shown in the drawings, in which

[0061] FIG. 1 shows a wind turbine,

[0062] FIG. 2 shows a schematic view of a wind turbine blade,

[0063] FIG. 3 shows a schematic view of a cross-section of a wind turbine blade,

[0064] FIG. 4 is a schematic cut-open view of a wind turbine blade according to the present invention,

[0065] FIG. 5 is an enlarged view of the encircled section in FIG. 4, and

[0066] FIGS. 6, 7 and 8 are perspective views of a spar structure according to the present invention.

DETAILED DESCRIPTION

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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 38 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.

[0074] 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.

[0075] FIG. 4 is a schematic cut-open, exploded view of a wind turbine blade according to the present invention, wherein FIG. 5 is an enlarged view of the encircled section in FIG. 4. According to the method of the present invention, a pressure side shell half and a suction side shell half are manufactured over the entire length L of the wind turbine blade 10. A spar structure 62 is arranged within the shell. The spar structure 62 comprising a first part 64 and a second part 66, the first and second part being releasably coupled to each other, as shown in FIG. 8. The method advantageously comprises fixing the first part 64 of the spar structure 62 to one or both of the shell halves within the first blade segment 68 and fixing the second part 66 of the spar structure to one or both of the shell halves within the second blade segment 70.

[0076] The shell halves are then closed and joined, such as glued together for obtaining a closed shell, which is subsequently cut along a cutting plane 69 substantially normal to the spanwise direction or longitudinal extent of the blade to obtain a first blade segment 68 and a second blade segment 70. The cutting plane 69 coincides with an end surface 65 of the first part 64 of the spar structure.

[0077] As seen in FIGS. 4 and 5, the spar structure 62 extends across the cutting plane 69. As best seen in FIG. 5, the first part 64 of the spar structure 62, which takes the form of a box-shaped sheath member for at least partly enclosing the second part 66 of the spar structure in the illustrated embodiment, is fixed to the first blade segment 68. The second part 66 of the spar structure 62, which comprises a spar box in the illustrated embodiment, is fixed to the second blade segment 70, wherein the second part 66 extends beyond the second blade segment 70 into the first blade segment 68, when the blade segments are assembled.

[0078] FIG. 5 also illustrates an access opening 80 cut through the upper half of the illustrated shell for accessing the spar structure and coupling and uncoupling the first and second part of the spar structure 62. For uncoupling, a locking pin, as illustrated in FIGS. 6-8, is withdrawn from the aligned respective apertures 76, 78 in each of the first and second part of the spar structure via the access opening 80. Prior to, or after, joining and sealing the first blade segment 68 to the second blade segment 70 for obtaining the wind turbine blade, the method advantageously comprises re-coupling the first and second part of the spar structure, via the access opening 80, as illustrated in FIG. 8, by re-inserting the locking pin 74 into the aligned respective apertures 76, 78 in each of the first and second part of the spar structure. As seen in FIGS. 4 and 5, the cutting step d1) does not comprise cutting the spar structure, only the shell halves are cut. In addition, two shear webs 82a, 82b are arranged within the first blade segment.

[0079] FIGS. 6-9 illustrate an embodiment of the spar structure 62 with the first part 64 in the form of a conductive, box-shaped sheath member. Preferably, the conductive sheath member is part of a lightning protection system of the wind turbine blade. The second part 66 of the spar structure comprises a box spar 67, part of which is encased in a jacket 72, for example comprising a conductive mesh 72. The spar structure 62 comprises a locking pin 74 for releasably coupling the first part 64 to the second part 66 of the spar structure through aligned respective locking apertures 76, 78 in each of the first and second part of the spar structure.

[0080] 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

[0081] 4 tower [0082] 6 nacelle [0083] 8 hub [0084] 10 blades [0085] 14 blade tip [0086] 16 blade root [0087] 18 leading edge [0088] 20 trailing edge [0089] 30 root region [0090] 32 transition region [0091] 34 airfoil region [0092] 36 pressure side shell part [0093] 38 suction side shell part [0094] 40 shoulder [0095] 41 spar cap [0096] 42 fibre layers [0097] 43 sandwich core material [0098] 45 spar cap [0099] 46 fibre layers [0100] 47 sandwich core material [0101] 50 first shear web [0102] 51 core member [0103] 52 skin layers [0104] 55 second shear web [0105] 56 sandwich core material of second shear web [0106] 57 skin layers of second shear web [0107] 60 filler ropes [0108] 62 spar structure [0109] 64 first part [0110] 65 end surface of first part [0111] 66 second part [0112] 67 spar member [0113] 68 first blade segment [0114] 69 cutting plane [0115] 70 second blade segment [0116] 72 jacket/mesh [0117] 74 locking pin [0118] 76 aperture [0119] 78 aperture [0120] 80 access opening [0121] 82 shear web [0122] L length [0123] r distance from hub [0124] R rotor radius