WIND TURBINE BLADE, MOLD, MANUFACTURING ARRANGEMENT AND METHOD FOR MANUFACTURING A WIND TURBINE BLADE

Abstract

A wind turbine blade is provided including a first and a second blade component connected with each other in an overlap region by thermal welding, the first blade component including a blade shell, a resistive element arranged between the first and second blade components in the overlap region as a remnant of the thermal welding, and an electrically conductive element extending through the blade shell and being electrically connected to the resistive element for supplying power to the resistive element during the thermal welding. The first and second blade components can be joined by thermal welding. Further, the resistive element used as heating element for thermal welding can be heated by electrical current even when the resistive element is difficult to assess from the interior cavity of the blade.

Claims

1. A wind turbine blade, comprising: a first and a second blade component connected with each other in an overlap region by thermal welding, the first blade component having a blade shell, a resistive element arranged between the first and second blade components in the overlap region as a remnant of the thermal welding, and an electrically conductive element extending through the blade shell and being electrically connected to the resistive element for supplying power to the resistive element during the thermal welding.

2. The wind turbine blade according to claim 1, wherein the electrically conductive element extending through the blade shell is arranged outside of the overlap region and/or the electrically conductive element is electrically connected to the resistive element by an electrical cable.

3. The wind turbine blade according to claim 1, wherein the electrically conductive element extending through the blade shell comprises a first end electrically connected to the resistive element and a second end for releasable electrical connection with a power source.

4. The wind turbine blade according to claim 3, wherein the second end of the electrically conductive element of the blade shell is configured for a releasable electric connection with a further electrically conductive element of a mold, the mold being configured for manufacturing the blade shell, and the further electrically conductive element being configured for electrical connection with the power source.

5. The wind turbine blade according to claim 4, wherein the second end of the electrically conductive element of the blade shell is configured for electrical connection with the further electrically conductive element of the mold by: a threaded connection, mating surfaces of the electrically conductive element and the further electrically conductive element, applying pressure for pressing the electrically conductive element and the further electrically conductive element to each other, and/or a plug-in connection.

6. The wind turbine blade according to claim 1, wherein the blade comprises the electrically conductive element in an outboard portion of the blade shell, and/or the blade comprises the electrically conductive element only in an outboard portion of the blade shell, and the outboard portion of the blade shell extends from a tip, of the blade in a direction of a root of the blade by a length of 80% or smaller, 70% or smaller, 60% or smaller, 50% or smaller and/or 40% or smaller of a total blade length.

7. The wind turbine blade according to claim 1, wherein the second blade component comprises a further blade shell or a structural element, a reinforcement beam, a web and/or a shear web, and/or the blade shell and/or the further blade shell comprises a blade half shell, a lower blade shell, an upper blade shell, a pressure side shell and/or a suction side shell.

8. A mold for manufacturing a wind turbine blade according to claim 1, comprising: a molding surface for molding the first blade component, the first blade component comprising the blade shell and the electrically conductive element extending through the blade shell and being connected to the resistive element of the blade, and a further electrically conductive element exposed at the molding surface for electrical connection with the electrically conductive element of the blade shell for supplying power to the resistive element for thermal welding.

9. A manufacturing arrangement for manufacturing a wind turbine blade, comprising a blade having a first and a second blade component connected with each other in an overlap region by thermal welding, the first blade component having a blade shell, a resistive element arranged between the first and second blade components in the overlap region as a remnant of the thermal welding, and an electrically conductive element extending through the blade shell and being electrically connected to the resistive element for supplying power to the resistive element during the thermal welding, wherein the electrically conductive element of the blade shell is electrically connected to the further electrically conductive element of the mold for supplying power to the resistive element of the blade for thermal welding.

10. A method for manufacturing a wind turbine blade, comprising the steps of: a) arranging a first and a second blade component such that they overlap with each other in an overlap region, wherein the first blade component comprises a blade shell and an electrically conductive element extending through the blade shell, wherein a resistive element is arranged between the first and second blade components in the overlap region, and the resistive element is electrically connected to the electrically conductive element, and b) connecting the first and second blade components to each other by thermal welding including supplying power through the electrically conductive element of the blade shell to the resistive element for heating the resistive element.

11. The method according to claim 10, wherein step a) includes closing an overall shell of the blade by arranging the first blade component on the second blade component or by arranging the first blade component on a further blade component, and step b) is carried out in the closed state of the overall blade shell. 12. The method according to claim 10, comprising the steps of: providing a mold with a molding surface and a further electrically conductive element exposed at the molding surface, and providing the first blade component with the electrically conductive element extending through its blade shell, wherein in step b), power is supplied through the further electrically conductive element of the mold and the electrically conductive element of the blade shell to the resistive element.

13. The method according to claim 10, comprising the step of manufacturing the first blade component by infusing a fiber lay-up arranged in a mold and the electrically conductive element embedded at least partially in the fiber lay-up with resin and curing the resin.

14. The method according to claim 10, comprising, before step a), the steps of: arranging the resistive element at the first blade component having the blade shell, and electrically connecting the electrically conductive element of the blade shell to the resistive element.

15. The method according to claim 10, comprising, before step a), the step of electrically connecting the electrically conductive element of the blade shell to a power source and/or electrically connecting the further electrically conductive element of the mold to the power source.

Description

BRIEF DESCRIPTION

[0056] Some of the embodiments will be described in detail with references to the following Figures, wherein like designations denote like members, wherein:

[0057] FIG. 1 shows a wind turbine according to an embodiment;

[0058] FIG. 2 shows a cross-section view of a wind turbine blade of the wind turbine of FIG. 1 according to an embodiment;

[0059] FIG. 3 shows a detail view of portion III of FIG. 2;

[0060] FIG. 4 illustrates an arrangement of resistive elements used as heating elements for joining blade components of the blade of FIG. 2 by thermal welding;

[0061] FIG. 5 shows a lower mold and a lower blade shell of the blade of FIG. 2 during a manufacturing step;

[0062] FIG. 6 shows an upper mold and an upper blade shell of the blade of FIG. 2 during a manufacturing step;

[0063] FIG. 7 shows a further embodiment of an upper mold and an upper blade shell of the blade of FIG. 2;

[0064] FIG. 8 shows a further embodiment of an upper mold and an upper blade shell of the blade of FIG. 2;

[0065] FIG. 9 shows a further embodiment of an upper mold and an upper blade shell of the blade of FIG. 2;

[0066] FIG. 10 shows a view similar as FIG. 6 with a resistive element used as heating element for thermal welding arranged in the upper blade shell;

[0067] FIG. 11 shows a view similar as FIG. 10 with a power source electrically connected to the resistive element;

[0068] FIG. 12 shows a view similar as FIG. 11 with an established joint between the upper blade shell and a shear web; and

[0069] FIG. 13 shows a flowchart illustrating a method for manufacturing a wind turbine blade of the wind turbine of FIG. 1 according to an embodiment.

DETAILED DESCRIPTION

[0070] FIG. 1 shows a wind turbine 1 according to an embodiment. The wind turbine 1 comprises a rotor 2 having one or more blades 3 connected to a hub 4. The hub 4 is connected to a generator (not shown) arranged inside a nacelle 5. During operation of the wind turbine 1, the blades 3 are driven by wind to rotate and the wind's kinetic energy is converted into electrical energy by the generator in the nacelle 5. The nacelle 5 is arranged at the upper end of a tower 6 of the wind turbine 1. The tower 6 is erected on a foundation 7 such as a monopile or concrete foundation. The foundation 7 is connected to and/or driven into the ground or seabed.

[0071] FIG. 2 shows a cross-section view of a wind turbine blade 3 of the wind turbine 1 of FIG. 1.

[0072] The blade 3 comprises an overall blade shell 8 including a lower blade shell 9 and an upper blade shell 10. The lower and upper blade shells 9, 10 are lower and upper blade shells with respect to a manufacturing position. The lower blade shell 9 is, for example, a pressure side shell and the upper blade shell 10 is, for example, a suction side shell or vice versa. The overall blade shell 8 surrounds an interior cavity 11 of the blade 3.

[0073] The blade 3 further comprises one or more structural elements 12 running in a longitudinal direction L1 of the blade 3. The longitudinal direction L1 of the blade 3 is, for example, pointing from a root 34 (FIG. 4) of the blade 3 to a tip 35 (FIG. 4) of the blade 3. The structural element 12 comprises fiber composite material, in particular glass fiber mats. The structural element 12 can be a shear web, a spar cap or the like. In FIG. 2, a shear web 13 is shown as an example for a structural element 12. Although not shown in the figures, the blade 3 can also comprise more than one shear web 13. The shear web 13 is connecting the blade shells 9, 10 of the pressure side and the suction side in the interior cavity 11 of the blade 3 and is providing shear strength to the blade 3. The shear web 13 comprises two flanges 14, 15 that are attached to inner surfaces 16, 17 of the shells 9, 10, respectively.

[0074] The blade 3 is, for example, assembled from several pre-manufactured blade components C1, C2, C3 such as the lower blade shell 9, the upper blade shell 10, the structural element 12 and/or the shear web 13. Such pre-manufactured blade components C1-C3 may, for example, be connected to each other at joints 18, 19, 20, 21 by thermal welding. For example, the lower blade shell 9 is connected to the upper blade shell 10 in a first and a second joint 18, 19 by thermal welding. The first and second connection regions 18, 19 are, in particular, arranged at a leading edge 22 and a trailing edge 23 of the blade 3. Although not shown in FIG. 2, the lower and upper blade shells 9, 10 may overlap each other at the joints 18, 19. Furthermore, the structural element 12 such as the shear web 13 is connected to the lower blade shell 9 in a third joint 20 by thermal welding and/or is connected to the upper blade shell 10 in a fourth joint 21 by thermal welding.

[0075] In the following, exemplarily, the fourth joint 21 between the shear web 13 and the upper blade shell 10 by thermal welding is described. However, the following description may also be applied to one, more or all of the other joints 18, 19, 20.

[0076] FIG. 3 shows a detail view of portion III of FIG. 2. Visible in FIG. 3 is a portion of the shear web 13 including its upper flange 15 and a portion of the upper blade shell 10. The upper blade shell 10 is an example of a first blade component C1. Further, the shear web 13 is an example of a second blade component C2. The shear web 13 and the upper blade shell 10 are connected with each other in an overlap region 24 by thermal welding. For providing the necessary heat for thermal welding, the blade 3 comprises a resistive element 25. The resistive element 25 is arranged between the shear web 13 (in particular the upper flange 15 of the shear web 13) and the upper blade shell 10 in the overlap region 24 during manufacture. Further, as can be seen in FIG. 3, the resistive element 25 remains after the manufacturing process in the blade 3. Also shown in FIG. 3 is that during the manufacturing process a weldable resin 26 is arranged between the shear web 13 (in particular the upper flange 15 of the shear web 13) and the upper blade shell 10 in the overlap region 24.

[0077] For joining of the two blade components C1, C2, the resistive element 25 is heated by supplying power I (electrical current I) to the resistive element 25. Since the resistive element 25 may be difficult to assess from the inner cavity 11 of the blade 3 (in particular when the cavity 11 is narrow as for the tip region of the blade 3), the blade 3 comprises an electrically conductive element 27 extending through the blade shell 10 for providing power I from outside 28 of the blade shell 10 (i.e., from outside 28 of the overall blade shell 8, FIG. 2).

[0078] The electrically conductive element 27 is at least partially embedded in the blade shell 10. The blade shell 10 with the electrically conductive element 27 is, for example, manufactured by infusing a fiber lay-up together with the electrically conductive element 27 embedded at least partially in the fiber lay-up with resin and curing the resin. The electrically conductive element 27 extends, for example, from the inner surface 17 of the blade shell 10 to an outer surface 29 of the blade shell 10.

[0079] The electrically conductive element 27 is electrically connected, for example by an electric cable 30, to the resistive element 25 (i.e., to a terminal 31 of the resistive element 25).

[0080] The resistive element 25 which is used as a heating element for the welding process during manufacture is left in the blade 3 as a remnant of the welding process. Further, also the electrically conductive element 27 and the electric connection 30 (cable 30) are left in the blade 3 as remnants of the welding process.

[0081] To avoid flashovers during lightning conditions, the resistive element 25and, thus, also the electrically conductive element 27 and the electric connection 30is electrically connected (reference sign 32) to a lightning conductor 33. Hence, the electrically conductive remnants 25, 27, 30 of the welding process can be integrated into a lightning protection system (not shown) of the blade 3.

[0082] In FIG. 3, reference sign E1 denotes a first end of the electrically conductive element 27 and E2 denotes a second end of the electrically conductive element 27.

[0083] As shown in FIG. 4, the blade 3 may comprise two or more of the resistive elements 25, 25 electrically connected to each other in series. Using more than one resistive element 25, 25 allows an easier heating of the resistive element 25, 25 even when the thermal welding process is carried out for a long bondline. In an embodiment, a length L of the blade 3 can be as large as 100 meter and more, using several resistive elements 25, 25.

[0084] In FIG. 4, a root 34 and a tip 35 of the blade 3 are illustrated. Further, as an example five resistive elements 25, 25 electrically connected to each other in series are shown. Each resistive element 25, 25 has first and second terminals 31, 36 for electrical connection with a neighboring resistive element 25, 25 and a power source 58 (FIG. 11). In FIG. 4, only the first and second terminals 31, 36 of the resistive element 25 are denoted with a reference sign.

[0085] As the inner cavity 11 of the blade 3 is increasingly difficult to assess when approaching the tip 35 of the blade 3, the blade 3 may comprise the means (i. e. the electrically conductive element 27 and the electric connection 30, FIG. 3) for supplying power I to the resistive element 25 from the outside 28 of the blade 3 in particular and/or only in the outboard portion 37 of the blade 3. The outboard portion 37 of the blade 3 may extend from the blade tip 35 in the direction D of the root 34 of the blade 3 by a length L2 of 80% or smaller, 70% or smaller, 60% or smaller, 50% or smaller and/or 40% or smaller of a total blade length L. The reference sign R denotes a maximum radius (or maximum height) of the inner cavity 11 which is regarded as assessable from inside the blade 3.

[0086] It is noted that FIG. 2 can be seen as a cross-section view along line A-A in FIG. 4.

[0087] In the following, a method for manufacturing the blade 3, in particular for joining the blade components C1-C3 (FIG. 2) is described with respect to FIGS. 5 to 13.

[0088] In the following, exemplarily, the fourth joint 21 (FIG. 2) between the shear web 13 and the upper blade shell 10 by thermal welding is described. However, the method described in the following may also be applied to one, more or all of the other joints 18, 19, 20 (FIG. 2).

[0089] In a first step S1 of the method, a lower mold 38 is provided for manufacturing the lower half shell 9, as shown in FIG. 5. In particular, a fiber lay-up is arranged in the lower mold 38 and infused with resin to pre-manufacture the lower half shell 9.

[0090] In a second step S2 of the method, the pre-manufactured lower shell 9 is joined with a pre-manufactured shear web 12, 13 by thermal welding, as shown in FIG. 5. In particular, a resistive element 39, a weldable resin (not shown in FIG. 5) and the shear web 13 are arranged on the lower shell 9. The resistive element 39 is electrically connected, for example by a cable 40, to a power source 41. It is noted that in FIG. 5 only one of two electrical connections between the power source 41 and the resistive element 39 are visible. Power is supplied to the resistive element 39 which is heated and, thus, melts or softens the weldable resin to provide a joint between the lower shell 9 and the shear web 13.

[0091] In this manufacturing state, there is only the lower shell 9 present but not yet the upper shell 10. Hence, the electrical connection of the power source 41 with the resistive element 39 can be easily performed from within the shell 9. Thus, no electrically conductive element extending through the blade shell 9such as the element 27 extending through the shell 10 in FIG. 2is necessary. In embodiments, however, such an electrically conductive element extending through the blade shell 9 may also be used for joining the low-er shell 9 and the web 13.

[0092] In a third step S3 of the method, the upper shell 10 is pre-manufactured, as shown in FIG. 6. In particular, an upper mold 42 is provided and a fiber lay-up together with an electrically conductive element 27 is arranged on a molding surface 43 of the upper mold 42 and infused with resin to pre-manufacture the upper half shell 10 having the electrically conductive element 27 extending through the shell 10.

[0093] The upper mold 42 comprises a further electrically conductive element 44 exposed at the molding surface 43 for electrical connection with the electrically conductive element 27 of the blade shell 10. Having the electrical contact provided by the electrically conductive element 27 of the shell 10 and the further electrically conductive element 44 of the mold 42, power I from a power source 58 (FIG. 11) can be guided such that it crosses the mold 42 and the shell 10 and is supplied to the resistive element 25 for thermal welding.

[0094] The blade shell 10 with the electrically conductive element and the mold 42 with the further electrically conductive element 44 form a manufacturing arrangement 45 for manufacturing the wind turbine blade 3.

[0095] In FIG. 6, a first embodiment of the electrically conductive element 27 and the further electrically conductive element 44 are shown. The electrical contact between the elements 27, 44 may be provided by applying pressure P such that the elements 27, 44 are pressed against each other at mating surfaces 46 and 47 of the elements 27 and 44, respectively.

[0096] FIGS. 7 to 9 show further embodiments of the electrically conductive element 27 and the further electrically conductive element 44.

[0097] In a second embodiment of the electrically conductive element 127 of the shell 110 (FIG. 7), a body 48 of the electrically conductive element 127 is casted in the shell 110 such that it is exposed at the outer surface 129 of the shell 110 (such as the outer surface 29 of the shell 10 in FIG. 2) for electrical contact with the further electrically conductive element 144. Further, the body 48 of the electrically conductive element 127 is casted in the shell 110 such that it is embedded at the inner surface 117 of the shell 110. The electrically conductive element 127 further comprises an electrical connection 49 for connection with the resistive element 25. The electrical connection 49 is, for example, provided by drilling a hole in the shell 110 and inserting an electric cable or an electrically conductive pin or the like.

[0098] The further electrically conductive element 144 of the mold 142 of the second embodiment comprises a different geometrical shape with respect to the further electrically conductive element 44 of the mold 42 of the first embodiment (FIG. 6). The further electrically conductive element 144 of the mold 142 comprises a stepped profile 50 towards the molding surface 143. Having the stepped profile 50 improves a vacuum condition during vacuum-induced resin infusion for casting the blade shell 110.

[0099] In a third embodiment of the electrically conductive element 227 of the shell 210 (FIG. 8), a body 51 of the electrically conductive element 227 is casted in the shell 210 such that it is completely embedded in the shell 210. The electrically conductive element 227 further comprises electrical connections 52, 53 for connection with the resistive element 25 and the power source 58, respectively.

[0100] The further electrically conductive element 144 of the mold 142 of the third embodiment is the same as for the second embodiment (FIG. 7).

[0101] In a fourth embodiment of the electrically conductive element 327 of the shell 310 (FIG. 9), a body 54 of the electrically conductive element 327 is casted in the shell 310 such that it is exposed at the outer surface 329 of the shell 310 (such as the outer surface 29 of the shell 10 in FIG. 2) for electrical contact with the further electrically conductive element 344. Further, the body 54 of the electrically conductive element 327 is casted in the shell 310 such that it is also exposed at the inner surface 317 of the shell 310 for electrical contact with the resistive element 25. In FIG. 9, the body 54 of the electrically conductive element 327 is shown to protrude from the inner surface 317 of the shell 310. However, in other examples, the body 54 of the electrically conductive element 327 may also be flush with the inner surface 317.

[0102] The electrically conductive element 327, in particular the body 54 of the electrically conductive element 327, comprises two holes 55, 56 with threads 57. In FIG. 9, only the threads 57 in the hole 55 have been denoted with a reference sign for illustration purposes. The threaded hole 55 is configured for electrical connection with the resistive element 25 (e.g., via the electric cable 30, FIG. 3). The further threaded hole 56 is configured for electrical connection with the power source 58 via the further electrically conductive element 344. In particular, the further electrically conductive element 344 according to the fourth embodiment comprises a threaded portion 57 with outer threads for engaging the threaded hole 56 of the electrically conductive element 327 (threaded connection T).

[0103] It is noted that the features described with respect to any of the first to fourth embodiment of the electrically conductive elements 27, 127, 227, 327 and the further electrically conductive elements 44, 144, 344 can be applied to any other of the first to fourth embodiment as suitable. For example, elements 27, 127, 227 may also comprises one or more threaded holes similar as element 327 for electrical (and mechanical) connections.

[0104] In a fourth step S4 of the method, the resistive element 25 is provided and the electrical connections of the resistive element 25 are established, as shown in FIG. 10. In particular, the electrically conductive element 27 of the shell 10 and the further electrically conductive element 44 of the mold 42 are electrically connected with each other. Depending on the embodiment of the electrically conductive elements 27, 44 (see FIGS. 6 to 9), this electrical connection is established by applying pressure P (e.g., FIG. 6) or by a threaded connection (e.g., FIG. 9) or by other means.

[0105] Further, in step S4, the resistive element 25 (and the weldable resin, not shown) is arranged on the upper shell 10 (FIG. 10). Then, the resistive element 25 is electrically connected with the electrically conductive element 27, for example by an electric cable 30. The electric cable 30 is, for example, arranged (e.g., laid) on the inner surface 17 of the upper shell 10 and fixed there.

[0106] Furthermore, a power source 58 is provided and electrically connected with the further electrically conductive element 44 of the mold 42.

[0107] In a fifth step S5 of the method, the upper shell 10 in the upper mold 42 is turned upside down and arranged on the lower shell 9 and the web 13 in the lower mold 38, as shown in FIG. 11. Hence, the overall blade shell 8 (FIG. 2) is closed.

[0108] In other embodiments, it is also possible to keep the upper shell 10 in its position and turn the lower shell 9 and the web 13 upside down and arrange them on the upper shell 10.

[0109] In a sixth step S6 of the method, the upper shell 10 and the web 13 are mechanically connected with each other by thermal welding. In particular, an electrical current I is supplied from the power source 58 and flows through an electrical cable 59, the further electrically conductive element 44 of the mold, the electrically conductive element 27 of the shell 10, the electrical cable 30 to the resistive element 25 for heating the resistive element 25. In this manner, the mechanical joint 21 between the upper shell 10 and the web 13 is established.

[0110] Further, also the joints 18 and 19 between the upper shell 10 and the lower shell 9 can be established in a similar manner as the joint 21.

[0111] In a seventh step S7 of the method, the power source 58 and the electrical connection 59 from the power source 58 to the further electrically conductive elements 44 of the upper mold 42 are removed.

[0112] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0113] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.