WO2016156184A1 - A fiber lay-up, a blade root for a wind turbine rotor blade, a wind turbine rotor blade and a method for producing a wind turbine rotor blade - Google Patents

A fiber lay-up, a blade root for a wind turbine rotor blade, a wind turbine rotor blade and a method for producing a wind turbine rotor blade Download PDF

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Publication number
WO2016156184A1
WO2016156184A1 PCT/EP2016/056505 EP2016056505W WO2016156184A1 WO 2016156184 A1 WO2016156184 A1 WO 2016156184A1 EP 2016056505 W EP2016056505 W EP 2016056505W WO 2016156184 A1 WO2016156184 A1 WO 2016156184A1
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WO
WIPO (PCT)
Prior art keywords
blade
wind turbine
spar cap
root
turbine rotor
Prior art date
Application number
PCT/EP2016/056505
Other languages
French (fr)
Inventor
Kasper Koops Kratmann
Karsten Schibsbye
Original Assignee
Siemens Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO2016156184A1 publication Critical patent/WO2016156184A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor 
    • F03D1/06—Rotors
    • F03D1/065—Rotors characterised by their construction elements
    • F03D1/0675—Rotors characterised by their construction elements of the blades
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2280/00—Materials; Properties thereof
    • F05B2280/60—Properties or characteristics given to material by treatment or manufacturing
    • F05B2280/6003—Composites; e.g. fibre-reinforced
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Definitions

  • the present invention relates to a fiber lay-up for a blade root of a wind turbine rotor blade, a blade root for a wind turbine rotor blade, a wind turbine rotor blade and a method for producing a wind turbine rotor blade.
  • Modern wind turbine rotor blades are built from fiber- reinforced plastics.
  • a rotor blade typically comprises an airfoil having a rounded leading edge and a sharp trailing edge.
  • the rotor blade is connected with its blade root to a hub of the wind turbine.
  • the blade root comprises a plurality of root bushings. Bolts are engaged with these root bushings to connect the blade root to the hub.
  • EP 1 486 415 Al describes such a root bushing. Forces have to be transmitted from the blade root into the root bushings. This is done by embedding the root bushings in fiber material .
  • a fiber lay-up for a blade root of a wind turbine rotor blade comprising a spar cap section and at least one side section that laterally branches from and runs at least partly parallel to the spar cap section.
  • the spar cap or beam preferably comprises the spar cap section of the fiber lay-up.
  • this evenly load transfer from the beam or spar cap of the wind turbine rotor blade into the root bushings is done by the branching side sections of the fiber lay-up.
  • the side sections are preferably arranged perpendicular to an end of the blade root or parallel to the root bushings. Further, the side sections are preferably arranged at least partly parallel to the spar cap section. The side sections alternatively can be arranged at least partly parallel to a leading and/or a trailing edge of the wind turbine rotor blade.
  • the spar cap section is broader than the at least one side section.
  • the number of side sections is arbitrarily.
  • the spar cap section and the side sections also can have the same width.
  • the spar cap section and the side sections can be made of one part.
  • the fiber lay-up can be made of glass fibers, carbon fibers, aramid fibers or the like.
  • the at least one side section has a curvature connecting a part of the at least one side section that runs parallel to the spar cap section with the spar cap section itself. The lay down of the lay-up on a mold can easily be performed by a robot as the robot can be programmed to lay an exact curvature. The curvature ensures an evenly and smooth load transfer from the side sections into the spar cap section.
  • a blade root for a wind turbine rotor blade is pro- vided, comprising such a fiber lay-up, wherein the spar cap section and the at least one side section are arranged perpendicularly to an end of the blade root .
  • An angle between the spar cap section and the end of the blade root and between the side sections and the end of the blade root is preferably 90° .
  • a part of the at least one side section runs parallel to the spar cap section, wherein the at least one side section has a curvature which connects the part that runs parallel to the spar cap section with the spar cap section itself.
  • the lay down of the lay-up on a mold can easily performed by a robot as the robot can be programmed to lay an exact curvature.
  • the curvature ensures an evenly and smooth load transfer from the side sections into the spar cap section .
  • the blade root comprises root bushings for connecting the blade root to a pitch bearing of a hub of a wind turbine, wherein the fiber lay-up transfers loads from the blade root into the root bushings.
  • each side section is related to a root bushing or a group of root bushings.
  • the root bushings are disposed evenly over a circumference of the blade root.
  • the at least one side section transfers loads from the spar cap section, a leading edge and/or a trailing edge of the wind turbine rotor blade into the root bushings.
  • the fiber lay-up follows the direction of tensile forces between the root bushings and the spar cap of the wind turbine rotor blade. This improves the performance and the durability of the wind turbine rotor blade.
  • the side sections preferably transfer loads from the leading edge and the trailing edge of the blade into the spar cap .
  • a wind turbine rotor blade comprising such a fiber lay-up and/or such a blade root.
  • the wind turbine rotor blade may be connected to the hub of a wind turbine by means of bolts that engage the root bushings.
  • a method for producing a wind turbine rotor blade comprising the steps of: laying a fiber lay-up comprising a spar cap section and at least one side section that laterally branches from and runs at least partly parallel to the spar cap section onto a mold, so that the at least one side section has a curvature, infiltrating the fiber lay-up with a resin and curing the resin to form the wind turbine rotor blade.
  • the infiltration of the fiber lay-up can be done in a vacuum assisted resin transfer molding (VARTM) process.
  • VARTM vacuum assisted resin transfer molding
  • After curing the resin the wind turbine rotor blade is re- moved from the mold.
  • the lay down of the lay-up can easily be performed by a robot as the robot can be programmed to lay an exact curvature.
  • the at least one side section is arranged in a blade root of the wind turbine rotor blade.
  • Wind turbine presently refers to an apparatus converting the wind's kinetic energy into rotational energy, which may again be converted to electrical energy by the apparatus.
  • Fig. 1 is a perspective view of a wind turbine according to one embodiment
  • Fig. 2 is a perspective view of a wind turbine rotor blade according to one embodiment
  • Fig. 3 is an end view of the wind turbine rotor blade according to Fig. 2 ;
  • Fig. 4 is a perspective view of a mold for producing a wind turbine rotor blade;
  • Fig. 5 is a perspective view of a mold for producing a wind turbine rotor blade;
  • Fig. 6 shows a block diagram of an embodiment of a method for manufacturing a wind turbine rotor blade.
  • FIG. 1 shows a wind turbine 1 according to an embodiment.
  • the wind turbine 1 comprises a rotor 2 connected to a generator (not shown) arranged inside a nacelle 3.
  • the nacelle 3 is arranged at an upper end of a tower 4 of the wind turbine 1.
  • the rotor 2 comprises three blades 5.
  • the blades 5 are connected to a hub 6 of the wind turbine 1.
  • Rotors 2 of this kind may have diameters ranging from, for example, 30 to 160 meters.
  • the blades 5 are subjected to high wind loads.
  • the blades 5 need to be lightweight.
  • blades 5 in modern wind turbines 1 are manufactured from fiber-reinforced composite materials.
  • glass fibers are generally preferred over carbon fibers for cost reasons. Oftentimes, glass fibers in the form of unidirectional fiber mats are used. Alternatively or in addition to the fiber mats, fiber rovings may be used.
  • Fig. 2 shows a blade 5 according to one embodiment.
  • the blade 5 comprises an aerodynamically designed portion 7, which is shaped for optimum exploitation of the wind energy and a blade root 8 for connecting the blade 5 to the hub 6.
  • the blade 5 may be fixed to the hub 6 by means of bolts.
  • Fig. 3 shows an end view of the blade root 8.
  • the blade root 8 comprises a plurality of root bushings 9 for a releasable connection of the blade 5 to the hub 6.
  • the root bushings 9 are embedded in the blade root 8 so that bolts (not shown) can be screwed into an internal thread of the root bushings 9 for a firm but releasable engagement therewith.
  • the number of root bushings 9 is arbitrarily. In Fig. 3 only three root bushings 9 are shown.
  • the root bushings 9 may be distributed evenly over a circumference of the blade root 8.
  • Fig. 4 is a perspective view of a mold 10 for producing such a blade 5.
  • the mold 10 comprises a lower mold half 11 shown in Fig. 4 and an upper mold half not shown in Fig. 4.
  • a fiber material for example a glass fiber material, constituting a shell 12 of the blade 5 after curing.
  • a foam core can be placed onto the laid up fiber material.
  • the root bushings 9 are embedded in the fiber material in the blade root 8.
  • the root bushings 9 may be distributed evenly in the blade root 8.
  • a curved shoulder 13 connects the blade root 8 with the aerodynamically designed portion 7.
  • a first embodiment of a fiber lay-up 14 is placed on the lower mold half 11 or on the fiber material of the shell 12 to reinforce a beam or spar cap 15 of the blade 5.
  • the lay-up 14 is part of the shell 12.
  • the spar cap 15 of the blade 5 is taking the majority of the loads acting on the blade 5 when being in use.
  • Most of the fiber material is located in the spar cap 15 as this zone is taking the majority of the loads on the blade 5 as coming from the winds influence on the ro- tor 2 of the wind turbine 1.
  • the fiber lay-up 14 is made of a fiber mat.
  • the fibers may comprise glass fibers, carbon fibers, aramid fibers or the like.
  • the fiber lay-up 14 comprises a spar cap section 16 which reinforces the spar cap 15 of the blade 5 and introduces loads from the blade 5 into the root bushings 9.
  • the spar cap section 16 is preferably straight and runs in a longitu- dinal direction L of the blade 5.
  • the spar cap section 16 has a width 16 .
  • the width 16 can narrow in the longitudinal direction L.
  • the spar cap section 16 may run from the blade root 8 into a tip of the blade 5. As can be seen from Fig. 4, the spar cap section 16 transfers loads from the blade 5 into a first group 17 of root bushings 9.
  • the fiber lay-up 14 further has side sections 18 to 20 that branch laterally from the spar cap section 16.
  • the number of side sections 18 to 20 is arbitrarily. As can be seen from Fig. 4, three side sections 18 to 20 are provided.
  • the side sections 18 to 20 and the spar cap section 16 are preferably made of one part.
  • the spar cap section 16 and the side sections 18 to 20 may be laid on the lower mold half 11 by a ro- bot (not shown) .
  • the side sections 18 to 20 transfer loads from the spar cap section 16, i.e. from the spar cap 15 of the blade 5 into groups 21, 22 of root bushings 9. Each group 17, 21, 22 can have one or several root bushings 9.
  • the side sections 18 to 20 can have a width b that is smaller than the width bie of the spar cap section 16.
  • the spar cap section 16 is arranged perpendicular to an end
  • Each side section 18 to 20 runs at least partly parallel to the spar cap section 16 and the lon- gitudinal direction L.
  • Each side section 18 to 20 has a part
  • the side sections 18 to 20 also have a curved part or a curvature 25 that connects the parallel part 24 with the spar cap section 16.
  • the curvature 25 can be exactly laid down on the lower mold half 11 by a robot . Due to the branched fiber lay-up 14, forces from the spar cap 15 of the blade 5 are optimally transferred to a pitch bearing of the hub 6 of the wind turbine 1. In particular, this load transfer from the beam or spar cap 15 of the blade 5 in- to the root bushings 9 is done by the curved constitution of the fiber lay-up 14.
  • the fiber lay-up 14 is laid onto the lower mold half 11 in the curvature 25. Further, it is perpendicular to the end 23 of the blade root 8 or parallel to the root bushings 9 and also parallel to the spar cap section 16 towards the tip of the blade 5.
  • the lay down of the lay-up 14 can be easily performed by a robot as the robot can be programmed to lay an exact curvature 25.
  • Fig. 5 is a further perspective view of the mold 10 known from Fig . 4.
  • the mold 10 comprises the lower mold half 11 and an upper mold half which is not shown.
  • Onto the lower mold half 11 is laid a fiber material constituting a shell 12 of the blade 5 after curing.
  • a second embodiment of a fiber lay-up 14 is placed on the lower mold half 11 or on the fiber material of the shell 12 to reinforce a beam or spar cap 15 of the blade 5.
  • the lay-up 14 is part of the shell 12.
  • the fiber lay-up 14 can be placed on the lower mold half 11 additionally or alternatively to the fiber lay-up 14 known from Fig. 4.
  • the fiber lay-up 14 is made of a fiber mat.
  • the fibers may comprise glass fibers, carbon fibers, aramid fibers or the like.
  • the fiber lay-up 14 comprises a spar cap section 16 which reinforces the spar cap 15 of the blade 5 and introduces loads from the blade 5 into the root bushings 9.
  • the spar cap section 16 is preferably straight and runs in a longitudinal direction L of the blade 5.
  • the spar cap section 16 has a width 16 .
  • the width 16 can narrow in the longitudinal direction L.
  • the spar cap section 16 may run from the blade root 8 into a tip of the blade 5. As can be seen from Fig. 5, the spar cap section 16 transfers loads from the blade 5 into a first group 17 of root bushings 9.
  • the fiber lay-up 14 further has side sections 18, 19 that branch laterally from the spar cap section 16.
  • the number of side sections 18, 19 is arbitrarily. As can be seen from Fig. 5, two side sections 18, 19 are provided.
  • the side sections 18, 19 and the spar cap section 16 are preferably made of one part.
  • the spar cap section 16 and the side sections 18, 19 may be laid on the lower mold half 11 by a robot (not shown) .
  • the side sections 18, 19 transfer loads from a leading edge 26 and a trailing edge 27 of the blade 5 into the spar cap 15 and from there into the group 17 of root bushings 9.
  • the side sections 18, 19 can have a width b that is smaller, the same or larger than the width 16 of the spar cap section 16.
  • the spar cap section 16 is arranged perpendicular to an end
  • Each side section 18, 19 runs at least partly parallel to the spar cap section 16 and the longitudinal direction L.
  • Each side section 18 to 20 has a part
  • the side sections 18, 19 also have a curved part or a curvature 25 that connects the parallel part 24 with the spar cap section 16.
  • the curvature 25 can be exactly laid down on the lower mold half 11 by a robot. Due to the branched fiber lay-up 14, forces from the spar cap 15 as well as from the leading edge 26 and the trailing edge 27 of the blade 5 are optimally transferred to a pitch bearing of the hub 6 of the wind turbine 1. In particular, this load transfer from the beam or spar cap 15 of the blade 5 in- to the root bushings 9 is done by the curved constitution of the fiber lay-up 14.
  • FIG. 6 shows a block diagram of an embodiment of a method for manufacturing such a blade 5.
  • the method comprises a step SI of laying the fiber lay-up 14 comprising the spar cap section 16 and the at least one side section 18 to 20 that laterally branches from and runs at least partly parallel to the spar cap section 16 onto the mold 10, preferably the lower mold half 11, so that the at least one side section 18 to 20 has a curvature 25.
  • the lay down can be performed by robot.
  • the method comprises a step S2 of infiltrating the fiber lay-up 14 with a resin. This can be done in a vacuum assisted resin transfer molding (VARTM) process.
  • VARTM vacuum assisted resin transfer molding
  • the resin is cured to form the blade 5.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Wind Motors (AREA)

Abstract

A fiber lay-up for a blade root of a wind turbine rotor blade, comprising a spar cap section and at least one side section that laterally branches from and runs at least partly parallel to the spar cap section. This has the advantage that an evenly load transfer from the root bushings to the beam or spar cap of the wind turbine rotor blade is ensured by the branching side sections of the fiber lay-up.

Description

Description
A fiber lay-up, a blade root for a wind turbine rotor blade, a wind turbine rotor blade and a method for producing a wind turbine rotor blade
The present invention relates to a fiber lay-up for a blade root of a wind turbine rotor blade, a blade root for a wind turbine rotor blade, a wind turbine rotor blade and a method for producing a wind turbine rotor blade.
Modern wind turbine rotor blades are built from fiber- reinforced plastics. A rotor blade typically comprises an airfoil having a rounded leading edge and a sharp trailing edge. The rotor blade is connected with its blade root to a hub of the wind turbine. The blade root comprises a plurality of root bushings. Bolts are engaged with these root bushings to connect the blade root to the hub. EP 1 486 415 Al describes such a root bushing. Forces have to be transmitted from the blade root into the root bushings. This is done by embedding the root bushings in fiber material .
It is one object of the present invention to provide an improved lay-up for a blade root of a wind turbine rotor blade.
Accordingly, a fiber lay-up for a blade root of a wind turbine rotor blade is provided, comprising a spar cap section and at least one side section that laterally branches from and runs at least partly parallel to the spar cap section.
Due to the branched fiber lay-up, forces from a beam or spar cap of the wind turbine rotor blade can be transferred to the root bushings. The spar cap or beam preferably comprises the spar cap section of the fiber lay-up. In particular, this evenly load transfer from the beam or spar cap of the wind turbine rotor blade into the root bushings is done by the branching side sections of the fiber lay-up. The side sections are preferably arranged perpendicular to an end of the blade root or parallel to the root bushings. Further, the side sections are preferably arranged at least partly parallel to the spar cap section. The side sections alternatively can be arranged at least partly parallel to a leading and/or a trailing edge of the wind turbine rotor blade.
According to an embodiment, the spar cap section is broader than the at least one side section. Preferably the number of side sections is arbitrarily. The spar cap section and the side sections also can have the same width. The spar cap section and the side sections can be made of one part. The fiber lay-up can be made of glass fibers, carbon fibers, aramid fibers or the like. According to a further embodiment, the at least one side section has a curvature connecting a part of the at least one side section that runs parallel to the spar cap section with the spar cap section itself. The lay down of the lay-up on a mold can easily be performed by a robot as the robot can be programmed to lay an exact curvature. The curvature ensures an evenly and smooth load transfer from the side sections into the spar cap section.
Further, a blade root for a wind turbine rotor blade is pro- vided, comprising such a fiber lay-up, wherein the spar cap section and the at least one side section are arranged perpendicularly to an end of the blade root . An angle between the spar cap section and the end of the blade root and between the side sections and the end of the blade root is preferably 90° .
According to an embodiment, beginning from the end of the blade root a part of the at least one side section runs parallel to the spar cap section, wherein the at least one side section has a curvature which connects the part that runs parallel to the spar cap section with the spar cap section itself. The lay down of the lay-up on a mold can easily performed by a robot as the robot can be programmed to lay an exact curvature. The curvature ensures an evenly and smooth load transfer from the side sections into the spar cap section . According to a further embodiment, the blade root comprises root bushings for connecting the blade root to a pitch bearing of a hub of a wind turbine, wherein the fiber lay-up transfers loads from the blade root into the root bushings. Preferably, each side section is related to a root bushing or a group of root bushings. In particular, the root bushings are disposed evenly over a circumference of the blade root.
According to a further embodiment, the at least one side section transfers loads from the spar cap section, a leading edge and/or a trailing edge of the wind turbine rotor blade into the root bushings. This means, the fiber lay-up follows the direction of tensile forces between the root bushings and the spar cap of the wind turbine rotor blade. This improves the performance and the durability of the wind turbine rotor blade. The side sections preferably transfer loads from the leading edge and the trailing edge of the blade into the spar cap .
Further, a wind turbine rotor blade is provided, comprising such a fiber lay-up and/or such a blade root. The wind turbine rotor blade may be connected to the hub of a wind turbine by means of bolts that engage the root bushings.
Further, a method for producing a wind turbine rotor blade is provided, comprising the steps of: laying a fiber lay-up comprising a spar cap section and at least one side section that laterally branches from and runs at least partly parallel to the spar cap section onto a mold, so that the at least one side section has a curvature, infiltrating the fiber lay-up with a resin and curing the resin to form the wind turbine rotor blade. The infiltration of the fiber lay-up can be done in a vacuum assisted resin transfer molding (VARTM) process. After curing the resin, the wind turbine rotor blade is re- moved from the mold. The lay down of the lay-up can easily be performed by a robot as the robot can be programmed to lay an exact curvature. According to an embodiment, the at least one side section is arranged in a blade root of the wind turbine rotor blade. Thus, loads can be optimally transferred from the spar cap of the wind turbine rotor blade into the root bushings . "Wind turbine" presently refers to an apparatus converting the wind's kinetic energy into rotational energy, which may again be converted to electrical energy by the apparatus.
Further possible implementations or alternative solutions of the invention also encompass combinations - that are not explicitly mentioned herein - of features described above or below with regard to the embodiments. The person skilled in the art may also add individual or isolated aspects and features to the most basic form of the invention.
Further embodiments, features and advantages of the present invention will become apparent from the subsequent description and dependent claims, taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a perspective view of a wind turbine according to one embodiment ;
Fig. 2 is a perspective view of a wind turbine rotor blade according to one embodiment;
Fig. 3 is an end view of the wind turbine rotor blade according to Fig. 2 ; Fig. 4 is a perspective view of a mold for producing a wind turbine rotor blade; Fig. 5 is a perspective view of a mold for producing a wind turbine rotor blade; and
Fig. 6 shows a block diagram of an embodiment of a method for manufacturing a wind turbine rotor blade.
In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated. Fig. 1 shows a wind turbine 1 according to an embodiment.
The wind turbine 1 comprises a rotor 2 connected to a generator (not shown) arranged inside a nacelle 3. The nacelle 3 is arranged at an upper end of a tower 4 of the wind turbine 1.
The rotor 2 comprises three blades 5. The blades 5 are connected to a hub 6 of the wind turbine 1. Rotors 2 of this kind may have diameters ranging from, for example, 30 to 160 meters. The blades 5 are subjected to high wind loads. At the same time, the blades 5 need to be lightweight. For these reasons, blades 5 in modern wind turbines 1 are manufactured from fiber-reinforced composite materials. Therein, glass fibers are generally preferred over carbon fibers for cost reasons. Oftentimes, glass fibers in the form of unidirectional fiber mats are used. Alternatively or in addition to the fiber mats, fiber rovings may be used.
Fig. 2 shows a blade 5 according to one embodiment. The blade 5 comprises an aerodynamically designed portion 7, which is shaped for optimum exploitation of the wind energy and a blade root 8 for connecting the blade 5 to the hub 6. The blade 5 may be fixed to the hub 6 by means of bolts. Fig. 3 shows an end view of the blade root 8.
The blade root 8 comprises a plurality of root bushings 9 for a releasable connection of the blade 5 to the hub 6. The root bushings 9 are embedded in the blade root 8 so that bolts (not shown) can be screwed into an internal thread of the root bushings 9 for a firm but releasable engagement therewith. The number of root bushings 9 is arbitrarily. In Fig. 3 only three root bushings 9 are shown. The root bushings 9 may be distributed evenly over a circumference of the blade root 8.
Fig. 4 is a perspective view of a mold 10 for producing such a blade 5.
The mold 10 comprises a lower mold half 11 shown in Fig. 4 and an upper mold half not shown in Fig. 4. Onto the lower mold half 11 is laid a fiber material, for example a glass fiber material, constituting a shell 12 of the blade 5 after curing. Onto the laid up fiber material a foam core can be placed. The root bushings 9 are embedded in the fiber material in the blade root 8. The root bushings 9 may be distributed evenly in the blade root 8. A curved shoulder 13 connects the blade root 8 with the aerodynamically designed portion 7.
A first embodiment of a fiber lay-up 14 is placed on the lower mold half 11 or on the fiber material of the shell 12 to reinforce a beam or spar cap 15 of the blade 5. The lay-up 14 is part of the shell 12. The spar cap 15 of the blade 5 is taking the majority of the loads acting on the blade 5 when being in use. Most of the fiber material is located in the spar cap 15 as this zone is taking the majority of the loads on the blade 5 as coming from the winds influence on the ro- tor 2 of the wind turbine 1. These loads are transferred into the hub 6 via the root bushings 9.
The fiber lay-up 14 is made of a fiber mat. The fibers may comprise glass fibers, carbon fibers, aramid fibers or the like. The fiber lay-up 14 comprises a spar cap section 16 which reinforces the spar cap 15 of the blade 5 and introduces loads from the blade 5 into the root bushings 9. The spar cap section 16 is preferably straight and runs in a longitu- dinal direction L of the blade 5. At the blade root 8 the spar cap section 16 has a width 16. The width 16 can narrow in the longitudinal direction L. The spar cap section 16 may run from the blade root 8 into a tip of the blade 5. As can be seen from Fig. 4, the spar cap section 16 transfers loads from the blade 5 into a first group 17 of root bushings 9.
The fiber lay-up 14 further has side sections 18 to 20 that branch laterally from the spar cap section 16. The number of side sections 18 to 20 is arbitrarily. As can be seen from Fig. 4, three side sections 18 to 20 are provided. The side sections 18 to 20 and the spar cap section 16 are preferably made of one part. The spar cap section 16 and the side sections 18 to 20 may be laid on the lower mold half 11 by a ro- bot (not shown) . The side sections 18 to 20 transfer loads from the spar cap section 16, i.e. from the spar cap 15 of the blade 5 into groups 21, 22 of root bushings 9. Each group 17, 21, 22 can have one or several root bushings 9. The side sections 18 to 20 can have a width b that is smaller than the width bie of the spar cap section 16.
The spar cap section 16 is arranged perpendicular to an end
23 of the blade root 8. Each side section 18 to 20 runs at least partly parallel to the spar cap section 16 and the lon- gitudinal direction L. Each side section 18 to 20 has a part
24 that runs parallel to the spar cap section 16. The parallel part 24 is arranged perpendicular to the end 23 of the blade root 8. An angle a between the parallel part 24 and the end 23 of the blade root 8 has 90°. The side sections 18 to 20 also have a curved part or a curvature 25 that connects the parallel part 24 with the spar cap section 16. The curvature 25 can be exactly laid down on the lower mold half 11 by a robot . Due to the branched fiber lay-up 14, forces from the spar cap 15 of the blade 5 are optimally transferred to a pitch bearing of the hub 6 of the wind turbine 1. In particular, this load transfer from the beam or spar cap 15 of the blade 5 in- to the root bushings 9 is done by the curved constitution of the fiber lay-up 14.
The fiber lay-up 14 is laid onto the lower mold half 11 in the curvature 25. Further, it is perpendicular to the end 23 of the blade root 8 or parallel to the root bushings 9 and also parallel to the spar cap section 16 towards the tip of the blade 5. The lay down of the lay-up 14 can be easily performed by a robot as the robot can be programmed to lay an exact curvature 25.
Fig. 5 is a further perspective view of the mold 10 known from Fig . 4. The mold 10 comprises the lower mold half 11 and an upper mold half which is not shown. Onto the lower mold half 11 is laid a fiber material constituting a shell 12 of the blade 5 after curing. A second embodiment of a fiber lay-up 14 is placed on the lower mold half 11 or on the fiber material of the shell 12 to reinforce a beam or spar cap 15 of the blade 5. The lay-up 14 is part of the shell 12. The fiber lay-up 14 can be placed on the lower mold half 11 additionally or alternatively to the fiber lay-up 14 known from Fig. 4.
The fiber lay-up 14 is made of a fiber mat. The fibers may comprise glass fibers, carbon fibers, aramid fibers or the like. The fiber lay-up 14 comprises a spar cap section 16 which reinforces the spar cap 15 of the blade 5 and introduces loads from the blade 5 into the root bushings 9. The spar cap section 16 is preferably straight and runs in a longitudinal direction L of the blade 5. At the blade root 8 the spar cap section 16 has a width 16. The width 16 can narrow in the longitudinal direction L. The spar cap section 16 may run from the blade root 8 into a tip of the blade 5. As can be seen from Fig. 5, the spar cap section 16 transfers loads from the blade 5 into a first group 17 of root bushings 9. The fiber lay-up 14 further has side sections 18, 19 that branch laterally from the spar cap section 16. The number of side sections 18, 19 is arbitrarily. As can be seen from Fig. 5, two side sections 18, 19 are provided. The side sections 18, 19 and the spar cap section 16 are preferably made of one part. The spar cap section 16 and the side sections 18, 19 may be laid on the lower mold half 11 by a robot (not shown) . The side sections 18, 19 transfer loads from a leading edge 26 and a trailing edge 27 of the blade 5 into the spar cap 15 and from there into the group 17 of root bushings 9. The side sections 18, 19 can have a width b that is smaller, the same or larger than the width 16 of the spar cap section 16. The spar cap section 16 is arranged perpendicular to an end
23 of the blade root 8. Each side section 18, 19 runs at least partly parallel to the spar cap section 16 and the longitudinal direction L. Each side section 18 to 20 has a part
24 that runs parallel to the spar cap section 16. The side sections 18, 19 also have a curved part or a curvature 25 that connects the parallel part 24 with the spar cap section 16. The curvature 25 can be exactly laid down on the lower mold half 11 by a robot. Due to the branched fiber lay-up 14, forces from the spar cap 15 as well as from the leading edge 26 and the trailing edge 27 of the blade 5 are optimally transferred to a pitch bearing of the hub 6 of the wind turbine 1. In particular, this load transfer from the beam or spar cap 15 of the blade 5 in- to the root bushings 9 is done by the curved constitution of the fiber lay-up 14.
An advantage of the fiber lay-ups 14 according to Figs. 4 and 5 is that the fibers, mats or rovings deviating from the lon- gitudinal direction L can run more unidirectional or even straight. Further, the amount of fibers needed for reinforcing the blade root 8 is reduced because the fiber lay-ups 14 do not extend over the whole width of the blade 5. Up to now, rotor blades 5 have often been produced by laying additional fiber layers near the blade root 8. These layers extend over the whole width of the mold 10 and their number increases towards the blade root 8. This design is called spate design. This production method does not have the advantages that can be achieved by using the above-described fiber lay-up 14. Fig. 6 shows a block diagram of an embodiment of a method for manufacturing such a blade 5.
The method comprises a step SI of laying the fiber lay-up 14 comprising the spar cap section 16 and the at least one side section 18 to 20 that laterally branches from and runs at least partly parallel to the spar cap section 16 onto the mold 10, preferably the lower mold half 11, so that the at least one side section 18 to 20 has a curvature 25. The lay down can be performed by robot. Further, the method comprises a step S2 of infiltrating the fiber lay-up 14 with a resin. This can be done in a vacuum assisted resin transfer molding (VARTM) process. Finally, in a step S3, the resin is cured to form the blade 5. Although the present invention has been described in accordance with preferred embodiments, it is obvious for the person skilled in the art that modifications are possible in all embodiments .

Claims

Patent claims
1. A fiber lay-up (14) for a blade root (8) of a wind turbine rotor blade (5) , comprising a spar cap section (16) and at least one side section (18 - 20) that laterally branches from and runs at least partly parallel to the spar cap section (16) .
2. The fiber lay-up according to claim 1, wherein the spar cap section (16) is broader than the at least one side section (18 - 20) .
3. The fiber lay-up according to claim 1 or 2 , wherein the at least one side section (18 - 20) has a curvature (25) con- necting a part (24) of the at least one side section (18 -
20) that runs parallel to the spar cap section (16) with the spar cap section (16) itself.
4. A blade root (8) for a wind turbine rotor blade (5), com- prising a fiber lay-up (14) according to one of claims 1 - 3, wherein the spar cap section (16) and the at least one side section (18 - 20) are arranged perpendicularly to an end (23) of the blade root (8) .
5. The blade root according to claim 4, wherein beginning from the end (23) of the blade root (8) a part (24) of the at least one side section (18 - 20) runs parallel to the spar cap section (16) , wherein the at least one side section (18 - 20) has a curvature (25) which connects the part (24) that runs parallel to the spar cap section (16) with the spar cap section (16) itself.
6. The blade root according to claim 4 or 5 , wherein the blade root (8) comprises root bushings (9) for connecting the blade root (8) to a pitch bearing of a hub (6) of a wind turbine (1), wherein the fiber lay-up (14) transfers loads from the blade root (8) into the root bushings (9) .
7. The blade root according to claim 6, wherein the at least one side section (18 - 20) transfers loads from the spar cap section (16) , a leading edge (26) and/or a trailing edge (27) of the wind turbine rotor blade (5) into the root bushings (9) .
8. A wind turbine rotor blade, comprising a fiber lay-up (14) according to one of claims 1 - 3 and/or a blade root (8) according to one of claims 4 - 7.
9. A method for producing a wind turbine rotor blade (5), comprising the steps of:
a) laying (SI) a fiber lay-up (14) comprising a spar cap section (16) and at least one side section (18 - 20) that laterally branches from and runs at least partly parallel to the spar cap section (16) onto a mold (10) , so that the at least one side section (18 - 20) has a curvature (25) ,
b) infiltrating the fiber lay-up (14) with a resin, and c) curing the resin to form the wind turbine rotor blade (5) .
10. The method according to claim 9, wherein the at least one side section (18 - 20) is arranged in a blade root (8) of the wind turbine rotor blade (5) .
PCT/EP2016/056505 2015-03-31 2016-03-24 A fiber lay-up, a blade root for a wind turbine rotor blade, a wind turbine rotor blade and a method for producing a wind turbine rotor blade WO2016156184A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP15162044.0 2015-03-31
EP15162044 2015-03-31

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2166202A (en) * 1984-10-30 1986-04-30 Rolls Royce Hollow aerofoil blade
EP1486415A1 (en) 2003-06-12 2004-12-15 SSP Technology A/S Wind turbine blade and method of manufacturing a blade root
US20090196756A1 (en) * 2008-02-05 2009-08-06 General Electric Company Wind turbine blades and method for forming same
EP2400147A1 (en) * 2010-06-25 2011-12-28 Siemens Aktiengesellschaft Root of the blade of a wind turbine
EP2697046A2 (en) * 2011-04-11 2014-02-19 LM WP Patent Holding A/S Wind turbine blade with tapering root bushings

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2166202A (en) * 1984-10-30 1986-04-30 Rolls Royce Hollow aerofoil blade
EP1486415A1 (en) 2003-06-12 2004-12-15 SSP Technology A/S Wind turbine blade and method of manufacturing a blade root
US20090196756A1 (en) * 2008-02-05 2009-08-06 General Electric Company Wind turbine blades and method for forming same
EP2400147A1 (en) * 2010-06-25 2011-12-28 Siemens Aktiengesellschaft Root of the blade of a wind turbine
EP2697046A2 (en) * 2011-04-11 2014-02-19 LM WP Patent Holding A/S Wind turbine blade with tapering root bushings

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