WIND TURBINE BLADE

Abstract

A wind turbine includes an elongated blade body extending from a root to a tip with a trailing edge, whereby at least one beam-like reinforcement means is integrated in the blade body adjacent to the trailing edge for reinforcing the region of the trailing edge, with the reinforcement means extending partly over the length of the blade body, wherein the reinforcement means is a pre-casted carbon beam including carbon fibers.

Claims

1. A wind turbine blade, comprising: an elongated blade body extending from a root to a tip with a trailing edge , whereby at least one reinforcement means is integrated in the elongated blade body adjacent to the trailing edge for reinforcing a region of the trailing edge, with the at least one reinforcement means extending partly over a length of the elongate blade body, wherein the at least one reinforcement means is a pre-casted carbon beam comprising carbon fibers.

2. The wind turbine blade according to claim 1, wherein the pre-casted carbon beam is made of a single pultruded carbon fiber profile or of a stack of two or more pultruded carbon fiber profiles or of several such stacks arranged side by side, and casted in a matrix material.

3. The wind turbine according to claim 2, wherein a biaxial material layer is arranged between two stacked pultruded carbon fiber profiles.

4. The wind turbine blade according to claim 2, wherein a height and/or a width of the stack varies over the length of the pre-casted carbon beam.

5. The wind turbine blade according to claim 2, wherein the pre-casted carbon beam has a rectangular, a trapezoidal, a polygonal, or a partially rounded cross section.

6. The wind turbine blade according to claim 2, wherein an elongated core element having a wedge -cross section is arranged at least at one side of the carbon beam and extends at least partially over the length of the pre-casted carbon beam.

7. The wind turbine blade according to claim 2, wherein the pre-casted carbon beam is arranged at one side next to an outer layer of the elongated blade body.

8. The wind turbine blade according to claim 7, wherein the pre-casted carbon beam is connected to a reinforcement glass beam comprising glass fibers, or to second carbon beam, which reinforcement glass beam or second carbon beam is arranged opposite to the pre-casted carbon beam at an opposite side next to an outer layer of the elongated blade body and is connected to the pre-casted carbon beam by a connection web.

9. The wind turbine blade according to claim 2, wherein a foam core element extending, seen in a cross section, towards the trailing edge is sandwiched at least partially between an upper shell and a lower shell of the elongated blade body .

10. The wind turbine blade according to claim 9, wherein a further core element is connected to the pre-casted carbon beam or to a core element and/or to the reinforcement glass beam next to the respective outer layer.

11. The wind turbine blade according to claim 1, wherein the pre-casted carbon beam is made of several pultruded carbon fiber rods or carbon fiber rovings casted in a matrix material.

12. The wind turbine blade according to claim 11, wherein the pre-casted carbon beam comprises solely carbon fiber rovings or hybrid carbon/glass fiber rovings.

13. The wind turbine blade according to claim 11, wherein the pre-casted carbon beam extends towards the trailing edge and is arranged next to at least one outer layer of the elongated blade body.

14. The wind turbine blade according to claim 13, wherein the pre-casted carbon beam extends to an opposite side of the elongated blade body having a cross section corresponding to a space defined by upper shell and the lower shell the and the trailing edge.

15. The wind turbine blade according to claim 14, wherein a foam core element is arranged adjacent to the pre-casted carbon beam extending further into the elongated blade body and extending between the lower shell and the upper shell.

16. The wind turbine blade according to claim 15, wherein further shell core elements connect to the foam core element next to both outer layers.

17. Awind turbine, with a rotor comprising several of the wind turbine blades according to claim 1.

Description

BRIEF DESCRIPTION

[0029] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0030] FIG. 1 shows a principle sketch of an inventive wind turbine comprising three inventive turbine blades;

[0031] FIG. 2 shows a partial cross section view of a wind turbine blade in the trailing edge region of a first embodiment of the wind turbine blade;

[0032] FIG. 3 shows a partial cross section view of a wind turbine blade in the trailing edge region of a second embodiment of the wind turbine blade; and

[0033] FIG. 4 a cross sectional view of another embodiment of a carbon beam.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a principle sketch of an inventive wind turbine 1, comprising a tower 2 with a nacelle 3 attached to the tower top and a rotor 4 having a hub 5, to which three wind turbine blades 6 are attached. Each wind turbine blade comprises a longitudinal blade body 7 with a root 8, by which it is attached to the hub, and a tip 9 at the blade body end. In view of the rotation direction each blade 6 further has a leading edge 10 and a trailing edge 11 on the other side. The respective trailing edge region of each blade 6 is specifically designed according to embodiments of the invention, which will be described in more detail in the following.

[0035] FIG. 2 shows a first embodiment of an inventive wind turbine blade 6 as a partial cross section view of the trailing edge region 12, which runs into the trailing edge 11. The blade body 7 comprises a first or upper shell 13 and a second or lower shell 14. The first or upper shell 13 comprises an outer layer 15 or layer stack, while the second or lower shell 17 comprises an outer layer 16 or layer stack, which are built of one or several fiber webs which are finally infused in a resin matrix.

[0036] Resulting from this shell construction, the inner 17 of the blade body 7 is hollow resulting in the necessity of reinforcing the shell structure. Problems specifically arise in the trailing edge region 12, which significantly varies its cross section seen from the root to the tip.

[0037] According to embodiments of the invention at least one reinforcement means 18 in form of a pre-casted respectively pre-fabricated carbon beam 19 comprising carbon fibers is integrated in the shell structure, here in the second or lower shell 14. In this embodiment the carbon beam 19 is made of a stack of three separate pultruded carbon fiber profiles 20, which are stacked above each other with carbon biaxial layers (not shown) between the profiles and which are pre-casted in a matrix material, usually a resin, which matrix material is used for fixing the separate profiles to a single carbon beam. The matrix material 30 is shown as an encapsulating material, but it also infuses the stack between the respective profiles, which may be distanced by some sandwiched glass fiber webs allowing an infusion of the sandwich area.

[0038] As FIG. 2 shows, the carbon beam has a rectangular cross section, as all pultruded carbon fiber profiles 20 have a rectangular cross section. It is obvious that by varying the width of the separate carbon fiber profiles 20 it is possible to vary the overall width of the stack respectively the carbon beam 19. It is furthermore possible to vary the cross sectional shape from a rectangular shape for example to a trapezoidal shape or the like simply by using pultruded carbon fiber profiles 20 having different width. Finally it is obvious that by varying the number of stacked carbon fiber profiles 20 the hight of the stack and finally the carbon beam 19 can also be varied.

[0039] The carbon beam 19 is arranged at the second or lower shell 14 next to the outer layer stack or layer 16. On both sides of the carbon beam 19 elongated core elements 21 having a wedge-like cross section are arranged for providing a smooth transition to the outer layer 16. These wedge-like core elements 21 may be made of wood like balsawood or a foam material or the like.

[0040] Adjacent to the right wedge-like core element 21 a further core element 22 is arranged, which has also a wedge-like edge section so that it smoothly fits with the core element 21. This core element 22 is also integrated into the shell 14 and stiffens the same.

[0041] On the opposite side respectively at the first or upper shell 13 another reinforcement means 23 in the form of a reinforcement glass beam 24 is integrated in the shell 13 respectively next to the outer layer 15. This glass beam 24 comprises a stack of separate glass fiber web layers which are embedded in the shell resin matrix and which glass beam stiffens the first or upper shell 13.

[0042] The carbon beam 19 and the glass beam 23 are connected by a connection web 25, which as a side web closes the trailing edge region 12 to the hollow inner 17 of the blade body 7. The connection web 25 is also embedded in the resin matrix material and therefore firmly attached to the respective inner fiber webs 26 covering the core elements 20, 21 and the carbon beam 19 respectively a core element 27 arranged in the upper shell 13 and connected to the glass beam 24.

[0043] As FIG. 2 furthermore shows, the remaining space between the upper and the lower shell 13, 14 and the connection web 25 is filled with a foam element 28 which extends, seen in the cross section, towards the trailing edge 11 and is directly connected to the resin infused shells 13, 14 and sandwiched in part between the carbon beam 19 and the wedge-like core element 21 on the one side and the glass beam 24 on the other side. This foam element 28 completely fills the remaining space and stiffens the direct edge area.

[0044] The carbon beam 19 provides extraordinary mechanical properties and allows for a very good stiffening and reinforcement of the trailing edge region 12. It allows to replace a large mass of glass fiber web and resin embedding the fibers, which are usually used to fill the trailing edge region and reinforce it by building a glass fiber beam extending along the trailing edge respectively the trailing region. Therefore by integrating the comparably small carbon beam 19 the mass of the blade can significantly be reduced. The carbon beam 19 is easy to handle during manufacturing of the blade, as the carbon beam 19 itself can directly be placed into the shell mould, in which the shell is manufactured. Furthermore it is possible to use a light-weight foam element 28 for filling the mature part of the space in the trailing edge region 12, which also contributes to the mass reduction.

[0045] The carbon beam 19 extends at least partially over the length of the trailing edge 11, but it runs almost entirely into the tip 9. Over its length it may change its width and/or hight according to the given space respectively the needed reinforcement or mechanical stability and properties.

[0046] FIG. 3 shows another embodiment of an inventive wind turbine blade 6, again comprising a blade body 7 with the trailing edge 11 and the trailing edge region 12. It also comprises a first or upper shell 13 with an outer layer 15 and a second or lower shell 14 with an outer layer 16.

[0047] In this embodiment also a reinforcement means 18 in form of a carbon beam 19 is integrated in the trailing edge region 12, but, compared to FIG. 3, the carbon beam 19 is here arranged very close to the trailing edge 11 and has a cross section which corresponds at least partially to the given cross section of the space between the upper and the lower shell 13, 14.

[0048] Here the carbon beam 19 comprises a plurality of pultruded carbon fiber rods 29, which are embedded in a matrix material 30, again a resin. The carbon fibers e.g. extend longitudinal towards the tip 9 and are embedded in the matrix material. The carbon fiber rods 29 are somehow soft and may therefore be arranged in a form where they can somehow be deformed in order to shape the overall cross section of the carbon beam 19, as FIG. 3 shows. In this final form or mould the rods 29 are then infused or embedded in the matrix material 30 which afterwards cures, so that a stable but specifically designed carbon beam 19 can be built.

[0049] The remaining space between the carbon beam 19 and the trailing edge 11 is filled with fiber webs 31 embedded in the resin matrix 32, which also embeds the respective web layers building the upper and lower shell 13, 14.

[0050] Adjacent to the carbon beam 19 a foam element 28 is arranged, which also extends between both shells 13, 14 and which fills the remaining space in the trailing edge region 12 between both shells 13, 14 and a connection web 25, which here connects the core elements 22 and 27 arranged in the shells 13 and 14 and is covered by respective webs 26, while the whole setup in the trailing edge region 12 is finally infused with the shell matrix material.

[0051] Also in this embodiment the carbon beam 19 comprising the pultruded rods 29 extends partially over the trailing edge length, but runs almost entirely to the tip 9. Also here it may certainly vary its width and hight, as it is designed to fill the space as far as possible, which space varies significantly along the its length to the tip 9.

[0052] While FIG. 3 shows a carbon beam 19 made of a plurality of separate pultruded carbon fiber rods 29, which comprise respective carbon fibers, it is also possible to build a comparable shape-designed carbon beam 19 by using carbon fiber rovings and embed the in a matrix. Such a carbon beam 19 built of carbon fiber rovings 33, which are embedded in a matrix material 30, is shown in a cross sectional view in FIG. 4. Only carbon fiber rovings may be used, or carbon and glass fiber for building a hybrid beam. The rovings extend along the longitudinal axis of the carbon beam 19 and therefore extend along the trailing edge 11 to the tip. Finally also carbon fiber webs may be used. Several fiber webs are stacked for building a web stack, which is then embedded in the matrix material. This web stack may comprise only carbon fiber webs or layers, but it may also be hybrid stack comprising several sandwiched glass fiber webs or layers, which glass fiber webs or layers allow a better infusion of the whole stack also in its volume.

[0053] 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.

[0054] 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.