Wind turbine rotor blade

Abstract

A wind turbine rotor blade, comprising: a wind turbine rotor blade shell structure comprising a fiber reinforced composite material; an electrical heating element arranged on an outer surface of the wind turbine rotor blade shell structure, the electrical heating element having an electrical heating conductor with an end portion; a power supply line extending in a longitudinal direction of the wind turbine rotor blade; and a connector electrically connecting the end portion of the heating conductor to the power supply line, where the connector includes an external thread directly screwed into the fiber reinforced composite material and the power supply line. The wind turbine rotor blade can be produced more easily and more cost-effectively.

Description

Technical Field

[0001] The utility model relates to a wind turbine rotor blade with an electric heating element. Background Art

[0002] WO 2022 / 263596 A1 discloses a wind turbine rotor blade having an electrical heating mat arranged on the inside of the wind turbine rotor blade shell. Electrical contact between the heating mat and a conductor cable arranged within the wind turbine rotor blade is achieved via a metal sheet. A disc-shaped metal block contacts the metal sheet and is connected to the conductor cable terminal block by inserting a metal connecting element into a hole drilled from the outside of the wind turbine rotor blade shell through the heating mat, the metal sheet, the disc-shaped metal block, and into the terminal block.

[0003] EP2526292B1 shows a wind turbine rotor blade equipped with an electric heating mat. The heating mat is wrapped in a copper mesh and placed on the outer surface of the wind turbine rotor blade. Cables placed inside the wind turbine rotor blade are connected to the heating mat via bolts. These bolts are guided through a copper block placed on the outside of the heating mat and locked by nuts placed inside the wind turbine rotor blade to apply a clamping force.

[0004] EP2843228A1 discloses a wind turbine rotor blade having an electric heating system comprising a plurality of electric heating elements arranged on the outer surface of the wind turbine rotor blade. Each heating element comprises a carrier layer and a heating conductor arranged on the carrier layer in a meandering pattern between two opposing edges of the heating element. End portions of the heating conductor are connected to power supply lines arranged on the pressure side and the suction side of the wind turbine rotor blade.

[0005] EP2754891B1 shows a wind turbine rotor blade with an electric heating pad, which is arranged on the outside of the blade shell and connected to a power supply lead arranged inside the wind turbine rotor blade. A conductive strip is placed on top of the heating pad. A bolt has a shaft that passes through the conductive strip, the pad, and the blade shell and is fixed in a nut inside the blade. The power supply lead is compressed between the blade shell and the nut, so that the electrical path of the current passes through the nut and bolt and into the pad and the conductive strip. This corresponds to the preamble features of the wind turbine rotor blade according to the present disclosure defined below. Utility Model Content

[0006] In view of the above, the object of the present invention is to provide a wind turbine rotor blade with an electric heating element and a corresponding manufacturing method, which can be produced more easily and cost-effectively.

[0007] This object is achieved by the following wind turbine rotor blade. Various aspects of the invention are given in the dependent claims.

[0008] The wind turbine rotor blade comprises

[0009] · A wind turbine rotor blade shell structure, the wind turbine rotor blade shell

[0010] The structure includes fiber-reinforced composite materials;

[0011] an electric heating element arranged on an outer surface of a wind turbine rotor blade shell structure, the electric heating element having an electric heating conductor with an end portion;

[0012] Power supply lines that run along the longitudinal direction of the wind turbine rotor blades

[0013] extension; and

[0014] a connector electrically connecting an end portion of the heating conductor to the power supply line; wherein

[0015] The connector includes external threads that screw into the fiber reinforced composite material and the power supply line.

[0016] A wind turbine rotor blade shell structure has an outer surface that corresponds to the aerodynamic surface of the wind turbine rotor blade. For example, the wind turbine rotor blade shell structure can be a wind turbine rotor blade half-shell (such as a pressure side half-shell or a suction side half-shell), or a longitudinal segment of such a half-shell. The inner surface of the wind turbine rotor blade shell structure generally faces the hollow interior space of the wind turbine rotor blade. The wind turbine rotor blade shell structure includes a fiber-reinforced composite material, which includes reinforcing fibers (such as glass fibers and / or carbon fibers) and a polymer, wherein the reinforcing fibers are embedded in the polymer. The fiber-reinforced composite material can also be referred to as a laminate. In addition, the wind turbine rotor blade shell structure can include additional components, such as core materials (such as polymer foam or balsa wood) and prefabricated components. These additional materials can be integrated into the wind turbine rotor blade shell structure, for example, by vacuum infusion, so that all the aforementioned components are embedded in a common polymer matrix.

[0017] The electric heating element has at least one heating conductor that is supplied with an electric heating current so that the outer surface of a wind turbine rotor blade covered by the electric heating element can be heated to prevent ice formation (anti-icing) or to remove ice that has already formed on the outer surface of the wind turbine rotor blade (de-icing). To conduct the electric heating current through the heating conductor, the end portions of the heating conductor are connected to a power supply line extending in the longitudinal direction of the wind turbine rotor blade. The power supply line is typically led to the root end of the wind turbine rotor blade and connected to a power supply at the root end. Typically, both ends of the electric heating element have end portions connected to the power supply line.

[0018] The electrical connection between the power supply line and the end portion of the heating conductor is achieved by a connector, which includes an external thread that is screwed directly into the fiber-reinforced composite material and the power supply line. This means that the external thread of the connector engages the inner surface of the opening in the fiber-reinforced material and the inner surface of the opening in the power supply line. The openings in both materials are filled with a part of the connector having an external thread. The inner surfaces of the fiber-reinforced composite material and the power supply line include such parts, which have internal threads or similar surface structures that directly engage with the external threads of the connector. As a result, the connector cannot be moved in its longitudinal direction without damaging the inner surface structure of the adjacent fiber-reinforced composite material or the inner surface structure of the power supply line.

[0019] In order to insert the connector into the fiber reinforced composite material and the power supply line, the connector has been screwed in. Correspondingly, in order to remove the connector without damaging the inner surface of the fiber reinforced composite material and the inner surface of the power supply line, the connector needs to be screwed out.

[0020] The resulting threaded connection is different from a bolt which merely passes through a corresponding opening and is locked by a nut on the opposite side. The outer threads of the connector are in direct contact with the surrounding fiber reinforced composite material and the power supply line and are therefore directly anchored in the fiber reinforced composite material and into the power supply line.

[0021] Electrical contact between the connector and the power supply line is provided by direct engagement of the external threads of the connector with adjacent inner surfaces of corresponding openings in the power supply line.

[0022] When making an electrical connection between a threaded connector and a power supply line, a person skilled in the art usually prepares two contact surfaces, each of which is as large as possible, and brings them into direct contact by applying pressure, in particular by clamping the two elements together (by means of a screw thread and a nut). The prior art document EP2754891B1 discussed in the introduction follows this approach. The inventors have recognized that in the specific application of an end portion of an electric heating element arranged on the outer surface of a wind turbine rotor blade, which end portion needs to be connected to the power supply line of the wind turbine rotor blade, a good electrical contact can also be achieved at the threaded portion of the connector when the connector is screwed directly into the power supply line. In this case, there is no need to tighten a nut onto the connector, which would be difficult, if not impossible, at least within the confined interior space of a wind turbine rotor blade.

[0023] The inventors have also realised that a sufficient or even better mechanical anchoring of the connector in the wind turbine rotor blade shell structure is achieved when the connector is also screwed directly into the fibre reinforced composite material.

[0024] Overall, the proposed solution provides good electrical contact and is easy to manufacture, thus being superior from an economic point of view.

[0025] In one aspect, the connector's external threads are self-threading. This means that there is no need to provide the fiber-reinforced composite material and the power supply line with internal threads before screwing the connector in. Instead, the connector can simply be screwed into the fiber-reinforced composite material and the power supply line, preferably after a cylindrical opening has been formed in these materials by drilling a hole with a diameter smaller than the external diameter of the external threads. Then, when the connector is screwed in, the external threads will cut corresponding, tightly fitting internal threads in the fiber-reinforced composite material and the power supply line. This makes inserting the connector particularly simple and automatically results in good electrical contact between the external threads and the power supply line, as well as a secure anchoring of the external threads into the fiber-reinforced material.

[0026] In one aspect, the connector is electrically connected to the power supply line solely via the external threads. This means that there is no additional contact between the connector and the power supply line beyond that between the external threads and the adjacent surface structure of the power supply line. There is no need to provide a nut for the connector. There is also no need to apply any clamping force between the connector and the power supply line. Furthermore, there is no need to form additional indirect electrical contact between the connector head portion and the power supply line, such as by placing a conductive sheath therebetween.

[0027] In one aspect, the connector includes a head portion that abuts an end portion of the heating conductor. As a result, good electrical contact is established between the connector and the end portion of the heating conductor. The required clamping force between the bottom surface of the head portion and the end portion of the heating conductor can be achieved by screwing the connector into the fiber-reinforced composite material to press the head portion against the end portion of the heating conductor disposed on the outer surface of the shell structure of the wind turbine rotor blade.

[0028] In one aspect, the connector is a screw with an external thread.The electrical contact between the connector and the end portion of the heating conductor can then be formed directly between the upper end / head portion of the screw.

[0029] In one aspect, the connector includes a threaded insert having an external thread and an internal thread. This is a good solution, particularly when a relatively large diameter external thread is desired to maximize the contact surface along the external thread. The internal thread can be used to connect the end portion of the electric heating element via an additional element of the connector.

[0030] In one aspect, the connector includes a screw having external threads that are screwed into internal threads of a threaded insert. The screw may have a head portion for contacting an end portion of the electrical heating element. An electrical connection between the screw and the threaded insert is automatically formed by the threaded connection therebetween.

[0031] In one aspect, the power supply line comprises a plurality of braided copper wires. The copper wires may have a relatively thin size, for example, a diameter in the range of 0.2 mm to 1.5 mm. The copper wires are braided so that the total cross-section is, for example, 50 mm. 2 The flexible power supply line can have a rectangular cross-section with a width ranging from 20 mm to 40 mm and a thickness ranging from 1.0 mm to 3.0 mm. As a result, sufficient electrical contact is achieved by screwing the outer thread of the connector into the arrangement of braided copper wires.

[0032] In one aspect, the power supply lines are arranged at the inner side of the rotor blade shell structure. The power supply lines can then be fixed to the rotor blade shell structure, for example, as long as the rotor blade shell structure is still in a manufacturing mold and / or has not yet been assembled with other shell structures to form a complete wind turbine rotor blade.

[0033] In one aspect, the power supply line is integrated into the rotor blade shell structure. This can be accomplished, for example, by placing the power supply line together with other components in a manufacturing mold during the manufacture of the wind turbine rotor blade shell structure, for example using a vacuum infusion method. This results in a secure integration of the power supply line, preferably on the inside of the rotor blade shell structure, so that when the connector is screwed into the wind turbine rotor blade shell structure, the power supply line can be easily accessed from the outside of the wind turbine rotor shell structure.

[0034] In one aspect, the end portion of the heating conductor comprises a cable connector. The cable connector is electrically and mechanically connected to the heating conductor, for example by crimping. The cable connector provides a reliable way of making electrical contact with the power supply line via the connector.

[0035] In one aspect, the heating conductor comprises a bundle of metal heating wires or carbon fibers. In both alternatives, the resistance of the heating conductor can be selected according to requirements, for example by selecting the number and / or thickness of the carbon fibers.

[0036] The above object is also solved by the following method.Preferred aspects are given in the dependent claims.

[0037] The method is for manufacturing a wind turbine rotor blade and comprises the following steps:

[0038] A wind turbine rotor blade is provided, the wind turbine rotor blade comprising

[0039] - a wind turbine rotor blade shell structure comprising a fiber-reinforced composite material,

[0040] an electric heating element arranged on an outer surface of a wind turbine rotor blade shell structure, said electric heating element having an electric heating conductor with an end portion,

[0041] - a power supply line extending in the longitudinal direction of the wind turbine rotor blade, and

[0042] • Connecting the power supply line to the end portion of the electrical heating conductor by screwing a connector comprising an external thread directly into the fiber reinforced composite material and the power supply line.

[0043] With regard to the features and advantages of the method, the above explanations for the relevant wind turbine rotor blade apply accordingly. In particular, the connection between the power supply line and the end portion of the heating conductor is achieved simply by screwing the connector with an external thread directly into the fiber-reinforced composite material and the power supply line.

[0044] In one aspect, the step of connecting the power supply line to the end portion of the electrical heating conductor comprises

[0045] Drilling holes in wind turbine rotor blade shell structures from the outside; and

[0046] • Screw the connector into the hole.

[0047] The diameter of the hole drilled into the wind turbine rotor blade shell structure is smaller than the outer diameter of the external thread, allowing the connector to be fastened to the wind turbine rotor blade shell structure through direct engagement between the external thread and the fiber-reinforced composite material. Regardless of whether the hole is also drilled into the power supply line, the external thread of the connector will also be screwed into the power supply line. In particular, in combination with self-cutting external threads, drilling only the hole in the fiber-reinforced material is sufficient. When screwing the connector in, the screw will also enter / pass through the power supply line, particularly when the power supply line is arranged beneath the fiber-reinforced composite material and / or is formed from braided copper wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Below, the present invention is explained in more detail based on the accompanying drawings. The accompanying drawings show:

[0049] Figure 1 is a schematic perspective view of a wind turbine rotor blade,

[0050] Figure 2 is a schematic diagram of the heating element,

[0051] Figure 3 for Figure 1 Cross-sectional view of a wind turbine rotor blade,

[0052] Figures 4 to 6 Schematic cross-sectional views showing three manufacturing steps using a connector including a threaded insert.

[0053] Figures 7 to 9 Three schematic cross-sectional views are shown illustrating the manufacturing steps of using a connector including a threaded insert. DETAILED DESCRIPTION

[0054] Figure 1 The wind turbine rotor blade 10 has a blade root 12, a blade tip 14, a leading edge 16, a trailing edge 18, and a longitudinal direction extending from the blade root 12 to the blade tip 14. A heating system 20 includes a plurality of electric heating elements 22 arranged on an outer surface of the wind turbine rotor blade. The wind turbine rotor blade includes two wind turbine rotor blade half shells, one on the pressure side and one on the suction side, which are adhered to each other along the leading edge 16 and the trailing edge 18. Each of the wind turbine rotor blade half shells is a wind turbine rotor blade shell structure.

[0055] The power supply line extends in the longitudinal direction of the wind turbine rotor blade 10 from the blade root 12 towards an outermost one of the electrical heating elements 22 .

[0056] Figure 2 An electric heating element 22 is shown, which comprises an electric heating conductor 26, which is arranged in a meandering manner on a base material 28. The electric heating conductor 26 has two end portions 30, each of which is provided with a cable connection 32.

[0057] Figure 3 Shown Figure 1 A cross-section of a wind turbine rotor blade 10 at a longitudinal location including an electric heating element 22 is shown. A substrate material 28 having a meandering portion of an electric heating conductor 26 extends over the leading edge 16. Two power supply lines are also shown. A first power supply line 34 is arranged on the pressure side of the wind turbine rotor blade 10, and a second power supply line 36 is arranged on the suction side of the wind turbine rotor blade 10. A first end portion 30 of the electric heating conductor 26 extends to the first power supply line 34, and a second end portion 30 of the electric heating conductor 26 extends to the second power supply line 36.

[0058] Figure 4 The first power supply line 34 is shown. Figure 3 . The wind turbine rotor blade shell structure comprises a fiber-reinforced composite material 38, such as a laminate having a thickness ranging from 2 mm to 50 mm, which forms an outer surface 40 of the wind turbine rotor blade shell structure. At the other side of the fiber-reinforced composite material 38, a first power supply line 34 is arranged. This first power supply line is surrounded by a core material 42 connected to the inner side of the fiber-reinforced composite material 38. Figure 4 The situation is shown before the end portion of the electric heating element 22 is mounted.

[0059] Figure 5 The reference image is shown after the cylindrical hole 44 has been drilled through the fiber reinforced composite material 38 and the first power supply line 34. Figure 4 The diameter of the hole 44 is smaller than the diameter of the external thread 48 of the connector 46 (see Figure 6 ).

[0060] exist Figure 6, the end portion 30 of the electrical heating conductor 26, as well as the cable gland 32 and the underlying gasket 58, have been placed at the outer surface 40 of the wind turbine rotor blade shell structure, and a connector 46 having an external thread 48 has been screwed into a hole, directly into the fiber-reinforced composite material 38 and the first power supply line 34. As indicated by the zigzag lines, the external threads 48 of the connector 46 directly engage the adjacent inner surface of the fiber-reinforced composite material 38 and the adjacent inner surface of the first power supply line 34. The connector 46 is thus mechanically anchored in the fiber-reinforced composite material 38 and is directly electrically connected to the first power supply line 34 via the external threads 48. The connector 46 also includes a head portion 50 that abuts the cable gland 32.

[0061] exist Figures 7 to 9 In the example shown, Figure 7 Situation and reference Figure 4 Same situation as described. Figure 8 and Figure 5 The difference is that a larger diameter hole 44 is drilled through the fiber reinforced composite material 38 and the first power supply line 34 .

[0062] Figure 9 A connector 46 is shown which in this case comprises a threaded insert 52 having an internal thread 56 and an external thread 48 having a greater Figure 6 The outer thread 48 of the screw-shaped connector 46 has a larger diameter. The threaded insert 52 has been screwed directly into Figure 8 Likewise, the external thread 48 results in a mechanical anchoring of the connector 46 in the fiber reinforced composite material 38 and in an electrical connection to the first power supply line 34 .

[0063] and Figure 6 on the contrary, Figure 9 The connector 46 is shown including an additional screw 54 which is screwed into an internal thread 56 of the threaded insert 52 and is used to secure and electrically connect the cable gland 32 to the threaded insert 52 .

[0064] Reference Signs List

[0065] 10 wind turbine rotor blades

[0066] 12 blade root

[0067] 14 blade end

[0068] 16 leading edge

[0069] 18 trailing edge

[0070] 20 Heating system

[0071] 22 Electric heating elements

[0072] 24 power supply lines

[0073] 26 Electric heating conductor

[0074] 28 base material

[0075] 30 end portion

[0076] 32 cable connector

[0077] 34 First power supply line

[0078] 36 Second power supply line

[0079] 38 Fiber-reinforced composite materials

[0080] 40 outer surface

[0081] 42 core material

[0082] 44 holes

[0083] 46 connectors

[0084] 48 external thread

[0085] 50 head part

[0086] 52 threaded inserts

[0087] 54 screws

[0088] 56 internal thread

[0089] 58 washers.

Claims

1. A wind turbine rotor blade (10), comprising A wind turbine rotor blade shell structure comprising a fiber reinforced composite material (38); an electric heating element (22) arranged on an outer surface (40) of the wind turbine rotor blade shell structure, the electric heating element (22) having an electric heating conductor (26) with an end portion (30); a power supply line (24) extending along the longitudinal direction of the wind turbine rotor blade (10); and A connector (46) electrically connecting the end portion (30) of the electrical heating conductor (26) to the power supply line (24); characterized in that the connector (46) includes an external thread (48) that is directly screwed into the fiber-reinforced composite material (38) and the power supply line (24).

2. The wind turbine rotor blade (10) according to claim 1, characterized in that The external thread (48) is self-cutting.

3. The wind turbine rotor blade (10) according to claim 1 or 2, characterized in that The connector (46) is electrically connected to the power supply line (24) only through the external thread (48).

4. The wind turbine rotor blade (10) according to claim 1 or 2, characterized in that The connector (46) includes a head portion that abuts an end portion (30) of the electrical heating conductor (26).

5. The wind turbine rotor blade (10) according to claim 1 or 2, characterized in that The connector (46) is a screw having the external thread (48).

6. The wind turbine rotor blade (10) according to claim 1 or 2, characterized in that The connector (46) includes a threaded insert (52) having the external threads (48) and internal threads (56).

7. The wind turbine rotor blade (10) according to claim 6, characterized in that The connector (46) includes a screw (54) having external threads that screw into internal threads (56) of the threaded insert (52).

8. The wind turbine rotor blade (10) according to claim 1 or 2, characterized in that The power supply line (24) includes a plurality of braided copper wires.

9. The wind turbine rotor blade (10) according to claim 1, wherein: The power supply line (24) is arranged at the inner side of the wind turbine rotor blade shell structure.

10. The wind turbine rotor blade (10) according to claim 1 or 2, characterized in that The power supply line (24) is integrated into the wind turbine rotor blade shell structure.

11. The wind turbine rotor blade (10) according to claim 10, characterized in that The power supply line (24) is integrated into the rotor blade shell structure in a vacuum infusion method.

12. The wind turbine rotor blade (10) according to claim 1 or 2, characterized in that The end portion (30) of the electrical heating conductor (26) comprises a cable connector (32).

13. The wind turbine rotor blade (10) according to claim 1 or 2, characterized in that The electric heating conductor (26) comprises a bundle of metal heating wires or carbon fibers.

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