Access arrangement for a wind turbine blade

Abstract

The present invention relates to an access arrangement (90) of a wind turbine blade for accessing a hollow space within the blade. The access arrangement (90) comprises an access opening (180) provided in the blade shell member, a cover panel (92) for covering the access opening (180), a sealing member (96) arranged between the cover panel (92) and the blade shell member, and one or more fasteners (98) for releasably fastening the cover panel (92) to the blade shell member. The present invention also relates to a wind turbine blade comprising the access arrangement (90).

Claims

1. A wind turbine blade having a profiled contour including a pressure side and a suction side, and a leading edge and a trailing edge with a chord having a chord length extending therebetween, the wind turbine blade extending in a spanwise direction between a root end and a tip end, wherein the wind turbine blade comprises a shell body with at least one pressure side shell member and at least one suction side shell member, and wherein the wind turbine blade comprises: a spar structure (62) comprising a first part (64) and a second part (66), the first and second parts (64, 66) being releasably coupled to each other; and an access arrangement (90) for accessing the spar structure (62) in a hollow space within the wind turbine blade, the hollow space being at least in part defined by a blade shell member (168), the access arrangement (90) comprising: an access opening (180) provided in the blade shell member (168); a cover panel (92) for covering the access opening (180); a sealing member (96) arranged between the cover panel (92) and the blade shell member (168); and one or more fasteners (98) for releasably fastening the cover panel (92) to the blade shell member (168), wherein each of the one or more fasteners (98) of the access arrangement (90) is releasably inserted in a respective one of aligned holes (88) provided in the cover panel (92), the sealing member (96) and the blade shell member (168), wherein the aligned holes (88) provided in the cover panel (92) are arranged annularly along an outer circumference of the cover panel (92), and wherein the aligned holes (88) provided in the cover panel (92), the sealing member (96) and the blade shell member (168) are arranged such that the cover panel (92) can be releasably fastened to the blade shell member (168) in a single spatial orientation only.

2. The wind turbine blade according to claim 1, wherein the access arrangement (90) further comprises a retaining member connecting the cover panel (92) and the blade shell member independently of the one or more fasteners (98).

3. The wind turbine blade according to claim 1, wherein the one or more fasteners (98) of the access arrangement (90) comprise one or more blind rivets.

4. The wind turbine blade according to claim 1, wherein the one or more fasteners (98) of the access arrangement (90) comprise a dielectric material.

5. The wind turbine blade according to claim 1, wherein the blade shell member has an outer surface, the outer surface of the blade shell member comprising an annular indentation (86) surrounding the access opening (180) for receiving the sealing member (96).

6. The wind turbine blade according to claim 1, wherein the aligned holes (88) provided in the blade shell member (168) are arranged annularly along an annular indentation (86) of an outer surface of the blade shell member (168), the aligned holes (88) surrounding the access opening (180).

7. The wind turbine blade according to claim 1, wherein the sealing member (96) of the access arrangement (90) is an annular gasket.

8. The wind turbine blade according to claim 1, wherein the access opening (180) of the access arrangement (90) covers an area of not more than 0.25 m.sup.2.

9. The wind turbine blade 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 parts (64, 66) of the spar structure (62).

10. A method of manufacturing an access arrangement (90) according to claim 1, comprising the steps of: arranging an implant in a mould for moulding a wind turbine blade shell part; arranging a fibre material on said mould and the implant; infusing the fibre material and implant with a resin; curing the resin to produce a hardened blade shell part; removing the implant from the hardened blade shell part to expose an indentation (86) on the surface of the shell part at the location of the implant; and drilling or cutting a hole through the shell part at the location of the indentation (86) to produce an access opening (180).

11. A method of manufacturing a wind turbine blade having a profiled contour including a pressure side and a suction side, and a leading edge and a trailing edge with a chord having a chord length extending therebetween, the wind turbine blade extending in a spanwise direction between a root end and a tip end, the method comprising the steps of: a1) manufacturing a pressure side shell half and a suction side shell half over substantially the entire length of the wind turbine blade; b1) arranging a spar structure (62) within one of the shell halves, the spar structure (62) comprising a first part (64) and a second part (66), the first and second part (66) being releasably coupled to each other; c1) closing and joining the shell halves for obtaining a closed shell; d1) cutting the closed shell along a cutting plane (69) substantially normal to the spanwise direction of the closed shell to obtain a first and a second blade segment (70), each blade segment comprising part of the pressure side shell half and part of the suction side shell half, wherein the spar structure (62) extends across the cutting plane (69); e1) uncoupling the first and second part (66) of the spar structure (62); f1) separating the first blade segment (68) from the second blade segment (70); and g1) joining and sealing the first blade segment (68) to the second blade segment (70) for obtaining the wind turbine blade, 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), and wherein the wind turbine blade comprises an access arrangement (90) according to claim 1.

12. The method according to claim 11, wherein step e1) comprises withdrawing the locking pin (74) from the aligned respective apertures in each of the first and second part (66) of the spar structure (62) via the access arrangement (90).

13. The method according claim 11, wherein the method further comprises a step f2) or h1) of re-inserting the locking pin (74) into the aligned respective apertures in each of the first and second part (66) of the spar structure (62) via the access arrangement (90).

14. A wind turbine blade obtainable by the method according to claim 11.

Description

DESCRIPTION OF THE INVENTION

(1) The invention is explained in detail below with reference to an embodiment shown in the drawings, in which

(2) FIG. 1 shows a wind turbine,

(3) FIG. 2 shows a schematic view of a wind turbine blade,

(4) FIG. 3 shows a schematic view of a cross-section of a wind turbine blade,

(5) FIG. 4 is a schematic cut-open view of a wind turbine blade,

(6) FIG. 5 is an enlarged view of the encircled section in FIG. 4, and

(7) FIGS. 6, 7 and 8 are perspective views of a spar structure,

(8) FIG. 9 is a partial perspective view of an access opening of a wind turbine blade according to the present invention,

(9) FIG. 10 is an exploded, partial perspective view of an access arrangement of a wind turbine blade according to the present invention,

(10) FIG. 11 is an assembled, partial perspective view of an access arrangement of a wind turbine blade according to the present invention,

(11) FIG. 12 is a cross-sectional view illustrating a fastener for releasably fastening a cover panel to a blade shell member according to the present invention, and

(12) FIG. 13 illustrates a method of manufacturing an access arrangement according to the present invention.

DETAILED DESCRIPTION

(13) 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.

(14) 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.

(15) 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.

(16) 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.

(17) 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.

(18) 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.

(19) FIG. 3 shows a schematic view of a cross section of the blade along the line 1-1 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.

(20) 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.

(21) FIG. 4 is a schematic cut-open, exploded view of a wind turbine blade according to a co-pending application of the present applicant, wherein FIG. 5 is an enlarged view of the encircled section in FIG. 4. A pressure side shell half and a suction side shell half are typically 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.

(22) 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.

(23) 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.

(24) FIG. 5 also illustrates an access opening 80 within 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.

(25) FIGS. 6, 7 and 8 illustrate an embodiment of the spar structure 62 with the first part 64 in the form of a conductive, box-shaped sheath member according to a co-pending application of the present applicant. 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.

(26) FIG. 9 is a partial perspective view of an access opening 180 of a wind turbine blade according to the present invention. The wind turbine blade comprises a shell member 138, such as a suction side shell half, with an outer surface 110. The shell member 138 may comprise a first segment 168, such as a root end segment, connected to a second segment 170, such as a tip end segment. An access opening 180 is provided in the blade shell member 138 for allowing access to a hollow space within the blade, e.g. for inserting or withdrawing a locking pin 174 as described above.

(27) FIGS. 10 and 11 illustrate an access arrangement 90 of a wind turbine blade according to the present invention in an exploded and assembled view, respectively. The access arrangement 90 comprises the access opening 180 provided in the blade shell member 138 and a cover panel 92 for covering the access opening 180. The outer surface 94 of the cover panel 92 is advantageously flush with the outer surface 110 of the cover panel 92 when the cover panel 92 is fastened to the blade shell member 138. Also, the cover panel 92 preferably has a curved outer surface 94 matching the curvature of the surrounding outer surface 110 of the blade shell member 138.

(28) The access arrangement 90 also comprises a sealing member 96 arranged between the cover panel 92 and the blade shell member 138. The sealing member 96 preferably takes the form of an annular gasket, as illustrated in FIG. 10. The access arrangement also comprises a plurality of fasteners 98 for releasably fastening the cover panel to the blade shell member, as illustrated in FIGS. 11 and 12. Each fastener is releasably inserted in aligned respective holes 88a,b,c provided in the cover panel 92, sealing member 96 and blade shell member 138. The holes 88a provided in the cover panel 92 are arranged annularly along an outer circumference of the cover panel 92.

(29) As also seen in FIG. 10, the outer surface 110 of the blade shell member 138 comprises an annular indentation 86 surrounding the access opening 180 for receiving the sealing member 96. The annular indentation 86 has a chamfered edge 100 smoothly leading towards the surrounding blade surface 110. FIG. 10 also illustrates a pad eye 84 which is attached to the inner surface of the cover panel 92 for securing the access panel when it is opened during installation or maintenance at height.

(30) FIG. 12 is a cross-sectional view illustrating a fastener 98 for releasably fastening a cover panel 92 to a blade shell member 138 according to the present invention. As described above, the fastener 98 is releasably inserted in aligned respective holes provided in the cover panel 92, sealing member 96 and blade shell member 138. The fastener 98 may be a blind rivet made from a polymer such as nylon, and having a head, a shank and a blind end. The rivet 98 may be supplied with a mandrel for expanding the blind end of the rivet.

(31) FIG. 13 illustrates different steps of a method of manufacturing an access arrangement according to the present invention. FIG. 13a shows a mould 102 in which an implant 104 is arranged, on top of which a fibre material 106 is placed. The fibre material 106 is infused with a resin and the resin is cured to produce a hardened blade shell part 138. As shown in FIG. 13b, the implant 104 is removed from the hardened blade shell part 138 to expose an indentation 86 on the surface of the shell part 138 at the location of the implant. A hole is drilled or cut through the shell part at the location of the indentation 86 to produce an access opening 180 as shown in FIG. 13c.

(32) 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

(33) 4 tower 6 nacelle 8 hub 10 blades 14 blade tip 16 blade root 18 leading edge 20 trailing edge 30 root region 32 transition region 34 airfoil region 36 pressure side shell part 38, 138 suction side shell part 40 shoulder 41 spar cap 42 fibre layers 43 sandwich core material 45 spar cap 46 fibre layers 47 sandwich core material 50 first shear web 51 core member 52 skin layers 55 second shear web 56 sandwich core material of second shear web 57 skin layers of second shear web 60 filler ropes 62 spar structure 64 first part 65 end surface of first part 66 second part 67 spar member 68, 168 first blade segment 69 cutting plane 70, 170 second blade segment 72 jacket/mesh 74, 174 locking pin 76 aperture 78 aperture 80, 180 access opening 82 shear web 84 pad eye 86 indentation 88 holes 90 access arrangement 92 cover panel 94 outer surface of cover panel 96 sealing member 98 fasteners 100 chamfered edge 102 blade mould 104 implant 106 fibre material 110 outer shell surface L length r distance from hub R rotor radius