Patent Description:
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modem wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.

The rotor blades generally include a suction side shell and a pressure side shell typically formed using molding processes that are bonded together at bond lines along the leading and trailing edges of the blade. Further, the pressure and suction shells are relatively lightweight and have structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. Thus, to increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more structural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the inner pressure and suction side surfaces of the shell halves.

In addition, conventional rotor blades require a substantial amount of bond paste to provide structure at various blade joints (e.g. at the leading or trailing edges of the rotor blade) to prevent local buckling of the suction and pressure side shells. Due to the complex geometry near these joint areas, it is often difficult to provide this structure in other ways that would be lighter than bond paste. Thus, conventional rotor blades typically utilize excess paste for the structure needed at the joints. Such excess paste, however, is expensive, heavy, and can limit the types of adhesives that can be used. For example, heavy and thick adhesive sections containing fast curing adhesives with high exothermic reactions can generate excess heat and damage the surrounding materials, thereby creating safety hazards. <CIT> discloses a rotor blade for a wind power plant having two rotor blade half-shells which are adhesively fastened to each other along leading edges and trailing edges of the half-shells. The half-shells each have a trailing edge girder, which at least in sections is of rectangular design in a cross-section along its longitudinal extent. <CIT> discloses a method of manufacturing a wind turbine blade comprising the steps of arranging an upper mould comprising a pre-casted fibre lay-up on a lower mould comprising a dry fibre layup and a mould core, applying vacuum to a space between the upper and lower moulds and the mould core, infusing at least the dry fibre-layup and a connection region between the dry fibre lay-up and the pre-casted fibre lay-up with a resin, and curing the resin.

In view of the foregoing, the art is continually seeking improved trailing edges for wind turbine rotor blades that address the aforementioned issues.

In one aspect, the present disclosure is directed to a method of forming a rotor blade. The method includes positioning one or more first dry skin layers in a first mold of the rotor blade. The method also includes placing a wedge-shaped core material atop the one or more first dry skins in the first mold at a trailing edge end of the rotor blade. The wedge-shaped core material includes a mounting surface. The method further includes infusing the one or more first dry skin layers and the wedge-shaped core material together via a resin material atop the first mold to form a first shell member of the rotor blade. Moreover, the method includes applying an adhesive, at least, onto the mounting surface of the wedge-shaped core material. In addition, the method includes placing a second mold with a second shell member of the rotor blade arranged therein atop the first mold containing the first shell member to form the rotor blade such that a portion of the second shell member rests atop the mounting surface of the wedge-shaped core material. Thus, the method includes securing the first and second shell members together via, at least, the adhesive applied between the second shell member and the mounting surface, wherein the wedge-shaped core material supports the trailing edge end of the rotor blade.

In an embodiment, the method may include forming the second shell member by positioning one or more second dry skin layers atop the second mold and infusing the one or more second dry skin layers with the resin material prior to placing the second mold atop the first mold.

In another embodiment, the method may include forming the wedge-shaped core material with at least one structural component embedded therein. For example, in one embodiment, the structural component(s) embedded in the wedge-shaped core material may have an I-beam cross-section.

In particular embodiments, the wedge-shaped core material may have a solid cross-section. In further embodiments, the wedge-shaped core material may be constructed of a high-density foam. In several embodiments, the wedge-shaped core material contacts inner surfaces of the first and second shell members.

In additional embodiments, the wedge-shaped core material may define a first end and an opposing, second end, with the second end being adjacent to a trailing edge of the rotor blade.

In yet another embodiment, the resin material may be, for example, a thermoset material or a thermoplastic material.

In another aspect, the present disclosure is directed to a method of forming a rotor blade. The method includes pre-forming a wedge-shaped core material via an infusion process. The wedge-shaped core material includes opposing surfaces that diverge together at an apex. Further, the opposing surfaces include at least one mounting surface. The method also include placing the pre-formed wedge-shaped core material atop one or more first dry skins in a first mold of the rotor blade. Moreover, the method includes co-infusing the one or more first dry skin layers and the pre-formed wedge-shaped core material together via a resin material atop the first mold to form a first shell member of the rotor blade. In addition, the method includes applying an adhesive, at least, onto the mounting surface of the wedge-shaped core material. As such, the method further includes placing a second mold with a second shell member of the rotor blade arranged therein atop the first mold containing the first shell member to form the rotor blade such that a portion of the second shell member rests atop the mounting surface of the wedge-shaped core material. Thus, the method includes securing the first and second shell members together via, at least, the adhesive applied between the second shell member and the mounting surface, wherein the wedge-shaped core material supports the trailing edge end of the rotor blade. It should be understood that the method may further include any of the additional features and/or steps as described herein.

In yet another aspect, the present disclosure is directed to a method of forming a rotor blade. The method includes forming a first shell member having one or more first outer skins, one or more first inner skins, and a first core material arranged between the one or more first outer and inner skins from a first end to a tapered, second end. The method also includes forming a second shell member having one or more second outer skins, one or more second inner skins, and a second core material arranged between the one or more second outer and inner skins from a first end to a tapered, second end. Further, a portion of the second shell member is constructed only of the one or more second outer and inner skins. Thus, the method includes arranging the first and second shell members at an interface such that the portion constructed only of the one or more second outer and inner skins of the second shell member is arranged adjacent to the tapered, second end of the first shell member such that the first core material extends up to a trailing edge of the rotor blade. The method also includes applying an adhesive at the interface. In addition, the method includes securing the first and second shell members together via, at least, the adhesive. It should be understood that the method may further include any of the additional features and/or steps as described herein.

In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention that is defined by the claims.

Generally, the present disclosure is directed to a method of forming a rotor blade of a wind turbine with an improved trailing edge connection. In one embodiment, a pre-kitted wedge-shaped core material (such as high-density foam) wrapped in fiberglass may be placed onto one or more first dry skin layers and infused with the dry skin layer(s) to form a first shell member. In another embodiment, an infused wedge-shaped core material may be placed onto one or more first dry skin layers and further infused with the dry skin layer(s) to form a first shell member. The first shell member thus provides a mounting surface or flange for an adhesive connection with a second shell member. The first and second shell members can then be easily secured together at the trailing edge via adhesive (such as glue, paste, or any other suitable adhesive, or similar). The first shell member thus provides a mounting surface or flange for an adhesive connection with a second shell member. The first and second shell members can then be easily secured together at the trailing edge via adhesive.

As such, the methods of the present disclosure provide many benefits not present in the prior art. For example, the methods of the present disclosure eliminate the need for a silicone profile to shape the fiberglass to construct the adhesive flange. Furthermore, the core material/foam is lightweight for easier handling and can be easily modified in shape to fit any blade type. In addition, the stiffness of the core material assists an operator with more accurately placing the wedge-shaped core material onto the dry skins, which was a challenge with the flexible silicone profile.

Referring now to the drawings, <FIG> illustrates one embodiment of a wind turbine <NUM> according to the present disclosure. As shown, the wind turbine <NUM> includes a tower <NUM> with a nacelle <NUM> mounted thereon. A plurality of rotor blades <NUM> are mounted to a rotor hub <NUM>, which is in turn connected to a main flange that turns a main rotor shaft (not shown). The wind turbine power generation and control components are housed within the nacelle <NUM>. The view of <FIG> is provided for illustrative purposes only to place the present invention in an exemplary field of use. It should be appreciated that the invention is not limited to any particular type of wind turbine configuration. In addition, the present invention is not limited to use with wind turbines, but may be utilized in any application having rotor blades. Further, the methods described herein may also apply to manufacturing any similar structure that benefits from printing a structure directly to skins within a mold before the skins have cooled so as to take advantage of the heat from the skins to provide adequate bonding between the printed structure and the skins. As such, the need for additional adhesive or additional curing is eliminated.

Referring now to <FIG>, perspective and cross-sectional views of one of the rotor blades <NUM> according to the present disclosure are illustrated. As shown, the rotor blade <NUM> generally includes a blade root <NUM> configured to be mounted or otherwise secured to the hub <NUM> (<FIG>) of the wind turbine <NUM> and a blade tip <NUM> disposed opposite the blade root <NUM>. A body shell <NUM> of the rotor blade generally extends between the blade root <NUM> and the blade tip <NUM> along a longitudinal axis <NUM>. The body shell <NUM> may generally serve as the outer casing/covering of the rotor blade <NUM> and may define a substantially aerodynamic profile, such as by defining a symmetrical or cambered airfoil-shaped cross-section. The body shell <NUM> may also define a pressure side <NUM> and a suction side <NUM> extending between leading and trailing edges <NUM>, <NUM> of the rotor blade <NUM>. Further, the rotor blade <NUM> may also have a span <NUM> defining the total length between the blade root <NUM> and the blade tip <NUM> and a chord <NUM> defining the total length between the leading edge <NUM> and the trialing edge <NUM>. As is generally understood, the chord <NUM> may vary in length with respect to the span <NUM> as the rotor blade <NUM> extends from the blade root <NUM> to the blade tip <NUM>.

In several embodiments, the body shell <NUM> of the rotor blade <NUM> may be formed as a single, unitary component. Alternatively, the body shell <NUM> may be formed from a plurality of shell components. For example, the body shell <NUM> may be manufactured from a first shell half generally defining the pressure side <NUM> of the rotor blade <NUM> and a second shell half generally defining the suction side <NUM> of the rotor blade <NUM>, with such shell halves being secured to one another at the leading and trailing ends <NUM>, <NUM> of the blade <NUM>.

Additionally, the body shell <NUM> may generally be formed from any suitable material. For instance, in one embodiment, the body shell <NUM> may be formed entirely from a laminate composite material, such as a carbon fiber reinforced laminate composite or a glass fiber reinforced laminate composite. Alternatively, one or more portions of the body shell <NUM> may be configured as a layered construction and may include a core material, formed from a lightweight material such as wood (e.g., balsa), foam (e.g., extruded polystyrene foam) or a combination of such materials, disposed between layers of laminate composite material. In addition, the body shell <NUM> may be constructed, at least in part, from a thermoset and/or a thermoplastic material.

The thermoplastic materials described herein generally encompass a plastic material or polymer that is reversible in nature. For example, thermoplastic materials typically become pliable or moldable when heated to a certain temperature and returns to a more rigid state upon cooling. Further, thermoplastic materials may include amorphous thermoplastic materials and/or semi-crystalline thermoplastic materials. For example, some amorphous thermoplastic materials may generally include, but are not limited to, styrenes, vinyls, cellulosics, polyesters, acrylics, polysulphones, and/or imides. More specifically, exemplary amorphous thermoplastic materials may include polystyrene, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), glycolised polyethylene terephthalate (PET-G), polycarbonate, polyvinyl acetate, amorphous polyamide, polyvinyl chlorides (PVC), polyvinylidene chloride, polyurethane, or any other suitable amorphous thermoplastic material. In addition, exemplary semi-crystalline thermoplastic materials may generally include, but are not limited to polyolefins, polyamides, fluropolymer, ethyl-methyl acrylate, polyesters, polycarbonates, and/or acetals. More specifically, exemplary semi-crystalline thermoplastic materials may include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene, polyphenyl sulfide, polyethylene, polyamide (nylon), polyetherketone, or any other suitable semi-crystalline thermoplastic material.

Further, the thermoset materials described herein generally encompass a plastic material or polymer that is non-reversible in nature. For example, thermoset materials, once cured, cannot be easily remolded or returned to a liquid state. As such, after initial forming, thermoset materials are generally resistant to heat, corrosion, and/or creep. Example thermoset materials may generally include, but are not limited to, some polyesters, some polyurethanes, esters, epoxies, or any other suitable thermoset material.

In addition, as mentioned, the thermoplastic and/or the thermoset material described herein may optionally be reinforced with a fiber material, including but not limited to glass fibers, carbon fibers, polymer fibers, wood fibers, bamboo fibers, ceramic fibers, nanofibers, metal fibers, or similar or combinations thereof. In addition, the direction of the fibers may include multi-axial, unidirectional, biaxial, triaxial, or any other another suitable direction and/or combinations thereof. Further, the fiber content may vary depending on the desired stiffness, and/or the location within the rotor blade <NUM>.

Referring particularly to <FIG>, the rotor blade <NUM> may also include one or more longitudinally extending structural components configured to provide increased stiffness, buckling resistance, and/or strength to the rotor blade <NUM>. For example, the rotor blade <NUM> may include one or more longitudinally extending spar caps <NUM>, <NUM> configured to be engaged against the opposing inner surfaces <NUM>, <NUM> of the pressure and suction sides <NUM>, <NUM> of the rotor blade <NUM>, respectively. Additionally, one or more shear webs <NUM> may be disposed between the spar caps <NUM>, <NUM> so as to form a beam-like configuration. The spar caps <NUM>, <NUM> may generally be designed to control the bending stresses and/or other loads acting on the rotor blade <NUM> in a generally span-wise direction (a direction parallel to the span <NUM> of the rotor blade <NUM>) during operation of a wind turbine <NUM>. Similarly, the spar caps <NUM>, <NUM> may also be designed to withstand the span-wise compression occurring during operation of the wind turbine <NUM>.

Referring now to <FIG>, a flow diagram of one embodiment of a method <NUM> of forming a rotor blade is illustrated. In general, the method <NUM> will be described herein with reference to the rotor blade <NUM> described above with reference to <FIG>. However, it should be appreciated by those of ordinary skill in the art that the disclosed method <NUM> may generally be utilized to manufacture any other rotor blade having any suitable configuration. In addition, although <FIG> depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure.

As shown at (<NUM>), the method <NUM> includes positioning one or more first dry skin layers in a first mold of the rotor blade <NUM>. As shown at (<NUM>), the method <NUM> includes placing a wedge-shaped core material atop the one or more first dry skins in the first mold at a trailing edge end of the rotor blade <NUM>. For example, as shown in <FIG>, the dry skin layer(s) <NUM> are placed atop the first mold <NUM>. Furthermore, the wedge-shaped core material <NUM> is placed atop the first dry skins(s) <NUM> and includes a mounting surface <NUM>.

In another embodiment, the method <NUM> may include forming the wedge-shaped core material <NUM> with at least one structural component <NUM> embedded therein. For example, in one embodiment, as shown in <FIG>, the structural component(s) <NUM> embedded in the wedge-shaped core material <NUM> may have an I-beam cross-section or any other shape to provide structural support thereto. In further embodiments, as shown in <FIG>, <FIG>, the wedge-shaped core material <NUM> may have a solid cross-section. Moreover, in an embodiment, the wedge-shaped core material <NUM> may be constructed of a high-density foam (e.g., such as polystyrene foam).

In additional embodiments, the wedge-shaped core material may define a first end and an opposing, second end, with the second end being adjacent to a trailing edge of the rotor blade <NUM>.

Referring back to <FIG>, as shown at (<NUM>), the method <NUM> includes infusing the first dry skin layer(s) <NUM> and the wedge-shaped core material <NUM> together via a resin material (e.g., such as thermoplastic resin or thermoset resin) atop the first mold <NUM> to form a first shell member of the rotor blade <NUM>. For example, as shown in <FIG>, the first shell member is illustrated as reference character <NUM>.

Referring back to <FIG>, as shown at (<NUM>), the method <NUM> includes applying an adhesive <NUM>, at least, onto the mounting surface <NUM> of the wedge-shaped core material <NUM>. For example, as shown in <FIG>, adhesive <NUM> is applied on the mounting surface <NUM> of the wedge-shaped core material <NUM>. In such embodiments, the adhesive <NUM> may include, for example, glue, paste, or any other suitable adhesive, or similar.

Referring back to <FIG>, as shown at (<NUM>), the method <NUM> includes placing a second mold <NUM> with a second shell member <NUM> of the rotor blade <NUM> arranged therein atop the first mold <NUM> containing the first shell member <NUM> to form the rotor blade <NUM> such that a portion of the second shell member <NUM> rests atop the mounting surface <NUM> of the wedge-shaped core material <NUM>. For example, as shown in <FIG>, a portion <NUM> of the second shell member <NUM> rests atop the mounting surface <NUM> of the wedge-shaped core material <NUM>. Thus, in such embodiments, as shown in <FIG> and <FIG>, the wedge-shaped core material <NUM> contacts inner surfaces of the first and second shell members <NUM>, <NUM>.

In an embodiment, the method <NUM> may include forming the second shell member <NUM> by positioning one or more second dry skin layers atop the second mold <NUM> and infusing the second dry skin layers with the resin material to form the second shell member <NUM> prior to placing the second mold <NUM> atop the first mold <NUM>. In other words, the second shell member <NUM> is already formed when placed adjacent to the first shell member <NUM>.

Accordingly, as shown at (<NUM>), the method <NUM> includes securing the first and second shell members <NUM>, <NUM> together via, at least, the adhesive <NUM> applied between the second shell member <NUM> and the mounting surface <NUM>. Thus, in the final rotor blade, the wedge-shaped core material <NUM> supports the trailing edge end of the rotor blade <NUM>.

As shown at (<NUM>), the method <NUM> includes pre-forming a wedge-shaped core material <NUM> via an infusion process. For example, as shown in <FIG>, the wedge-shaped core material <NUM> includes opposing surfaces <NUM>, <NUM> that diverge together at an apex <NUM>. Further, as shown, the opposing surfaces <NUM>, <NUM> include at least one mounting surface <NUM>.

Referring back to <FIG>, as shown at (<NUM>), the method <NUM> includes placing the pre-formed wedge-shaped core material <NUM> atop one or more first dry skins <NUM> in a first mold <NUM> of the rotor blade <NUM>. Thus, as shown at (<NUM>), the method <NUM> includes co-infusing the first dry skin layer(s) <NUM> and the pre-formed wedge-shaped core material <NUM> together via a resin material atop the first mold <NUM> to form the first shell member <NUM> of the rotor blade <NUM>. As shown at (<NUM>), the method <NUM> includes applying an adhesive, at least, onto the mounting surface <NUM> of the wedge-shaped core material <NUM>. As shown at (<NUM>), the method <NUM> includes placing a second mold (e.g., as described with reference to <FIG>) with a second shell member <NUM> of the rotor blade <NUM> arranged therein atop the first mold containing the first shell member to form the rotor blade <NUM> such that a portion of the second shell member rests atop the mounting surface <NUM> of the wedge-shaped core material <NUM>. Thus, as shown at (<NUM>), the method <NUM> includes securing the first and second shell members <NUM>, <NUM> together via, at least, the adhesive applied between the second shell member <NUM> and the mounting surface <NUM>, wherein the wedge-shaped core material <NUM> supports the trailing edge end of the rotor blade <NUM>.

As shown at (<NUM>), the method <NUM> includes forming a first shell member <NUM> having one or more first outer skins <NUM>, one or more first inner skins <NUM>, and a first core material <NUM> arranged between the first outer and inner skins <NUM>, <NUM> from a first end <NUM> to a tapered, second end <NUM>. As shown at (<NUM>), the method <NUM> includes forming a second shell member <NUM> having one or more second outer skins <NUM>, one or more second inner skins <NUM>, and a second core material <NUM> arranged between the second outer and inner skins <NUM>, <NUM> from a first end <NUM> to a tapered, second end <NUM>. Further, as shown particularly in <FIG>, a portion <NUM> of the second shell member <NUM> is constructed only of the second outer and inner skins <NUM>, <NUM>, i.e., the portion is absent to the core material <NUM>. Thus, referring back to <FIG>, as shown at (<NUM>), the method <NUM> includes arranging the first and second shell members <NUM>, <NUM> at an interface <NUM> such that the portion <NUM> constructed only of the second outer and inner skins <NUM>, <NUM> of the second shell member <NUM> is arranged adjacent to the tapered, second end <NUM> of the first shell member <NUM> such that the first core material <NUM> extends up to (or closer to) the trailing edge <NUM> of the rotor blade <NUM>. Moreover, as shown at (<NUM>), the method <NUM> includes applying an adhesive <NUM> at the interface <NUM> (and as further illustrated in <FIG>). In addition, as shown at (<NUM>), the method <NUM> includes securing the first and second shell members <NUM>, <NUM> together via, at least, the adhesive <NUM>.

Claim 1:
A method (<NUM>) of forming a rotor blade (<NUM>), the method comprising:
positioning (<NUM>) one or more first dry skin layers in a first mold (<NUM>) of the rotor blade (<NUM>);
placing (<NUM>) a wedge-shaped core material (<NUM>, <NUM>) atop the one or more first dry skins in the first mold (<NUM>) at a trailing edge end of the rotor blade (<NUM>), the wedge-shaped core material (<NUM>, <NUM>) comprising a mounting surface (<NUM>, <NUM>);
infusing (<NUM>) the one or more first dry skin layers and the wedge-shaped core material (<NUM>, <NUM>) together via a resin material atop the first mold (<NUM>) to form a first shell member (<NUM>) of the rotor blade (<NUM>);
applying (<NUM>) an adhesive, at least, onto the mounting surface (<NUM>, <NUM>) of the wedge-shaped core material (<NUM>, <NUM>);
placing (<NUM>) a second mold (<NUM>) with a second shell member (<NUM>) of the rotor blade (<NUM>) arranged therein atop the first mold (<NUM>) containing the first shell member (<NUM>) to form the rotor blade (<NUM>) such that a portion of the second shell member (<NUM>) rests atop the mounting surface (<NUM>, <NUM>) of the wedge-shaped core material (<NUM>, <NUM>); and,
securing (<NUM>) the first and second shell members (<NUM>, <NUM>) together via, at least, the adhesive applied between the second shell member (<NUM>) and the mounting surface (<NUM>, <NUM>), wherein the wedge-shaped core material (<NUM>, <NUM>) supports the trailing edge end of the rotor blade (<NUM>).