Patent Description:
Modern wind turbines usually include a rotor with a considerable diameter size, as illustrated in <FIG>. Referring to <FIG>, a wind turbine <NUM> is typically mounted on a tower <NUM> and includes a wind turbine nacelle <NUM> positioned on top of the tower. The wind turbine rotor, including three wind turbine blades <NUM>, is connected to the nacelle <NUM> through the low speed shaft, which extends out of the nacelle front. As illustrated in <FIG>, wind beyond a certain level will activate the rotor due to the lift induced on the blades and allow it to rotate in a perpendicular direction to the wind. The rotation movement is converted to electric power, which is usually supplied to the transmission grid as known by skilled persons within the area.

Wind turbine blades for modern wind turbines are typically approaching lengths of <NUM> meters and more. Large three-bladed wind turbine blades typically rotate with tip speeds in the range of <NUM> to <NUM> meters per second. For some two-bladed turbines, the blades can rotate with a tip speed as high as <NUM> meters per second. This causes very severe aerodynamic conditions at the tip of the blade as well as along the outer ⅓ of the leading edge, leading to blade loss in these areas. Although wind blades are typically expected to last for <NUM> years, this is often not the case due to the loss caused by aerodynamic conditions to the leading edge necessitating blade repair. However, repair of the leading edge is not easy since it is typically carried out with the blade still erected on the turbine. This also has significant cost and safety implications, particularly if the wind turbine is located offshore.

In order to create wind turbine blades that are capable of withstanding the significant forces of the wind as well as their own weight, the blades are constructed with two glass fiber shells and one or more internal glass fiber load-bearing beams, ribs etc., all adhered to each other.

Current wind turbine blades are typically made by laying rolls of fabric into large half molds to build up the blade laminate layer by layer in the mold, see for example <CIT>. This conventional process has a number of shortcomings, namely it is slow and consumes a lot of time in the mold which is the process constraint, there is also a high risk of layup defects like wrinkles by depositing fabrics in such a way. The problems are getting worse as blades are getting bigger since a greater proportion of the blade cycle time is used to lay fabric into the mold. Another additional problem is that it is very hard to automate and reduce labor content of the blade manufacturing process due to the large and constantly changing scale of the blades.

Efforts have been made to try and automate the conventional process, but the constantly evolving scale of wind blades caused much of the investment to be lost when products change and also the sheer size of the entire component makes the investment very high.

There remains scope for improving automation and reducing labor content in manufacturing wind turbine rotors or blades.

According to one aspect of the invention, there is provided a wind turbine blade including a shell structure defining a leading edge and a trailing edge, and an upwind shell and a downwind shell joined along at least one of the leading edge or the trailing edge. The shell structure includes an assembly of preformed parts processed into a collection of prefabricated laminates.

According to the invention, the shell structure includes a spar cap laminate made from a first plurality of spar cap preformed parts, a root laminate made from a second plurality of blade root preformed parts, and an aerodynamic fairing laminate made from a third plurality of aerodynamic fairing preformed parts. Preferably, each of the first plurality of spar cap preformed parts, the second plurality of blade root preformed parts, and the third plurality of aerodynamic fairing preformed parts has a mass less than <NUM>.

In another preferred embodiment, each of the first plurality of spar cap preformed parts, the second plurality of blade root preformed parts, and the third plurality of aerodynamic fairing preformed parts is less than <NUM> in length.

In a further preferred embodiment, each of the first plurality of spar cap preformed parts, the second plurality of blade root preformed parts, and the third plurality of aerodynamic fairing preformed parts is created flat and configured to take a shape of the blade when assembled in plurality.

In yet another preferred embodiment, more than <NUM>% of the first plurality of spar cap preformed parts, more than <NUM>% of the second plurality of blade root preformed parts, and more than <NUM>% of the third plurality of aerodynamic fairing preformed parts are identical.

In another preferred embodiment, each of the first plurality of spar cap preformed parts, the second plurality of blade root preformed parts, and the third plurality of aerodynamic fairing preformed parts includes one or more of: thermosetting or thermoplastic resin and further, each of the plurality of preformed parts includes one or more of: no fiber, short fiber or continuous fiber.

In another preferred embodiment, each of the first plurality of spar cap laminate preformed parts comprises predominantly greater that <NUM>% unidirectional (UD) fiber. Advantageously, each of the first plurality of spar cap laminate preformed parts has tapered ends.

In another preferred embodiment, each of the second plurality of root laminate preformed parts comprises a mixture of UD fiber and +/-<NUM> fiber. Advantageously, each of the second plurality of root laminate preformed parts has tapered ends.

In yet another preferred embodiment, each of the third plurality of aerodynamic fairing preformed parts comprises predominantly +/-<NUM> fiber and a core. Advantageously, each of the third plurality of aerodynamic fairing preformed parts comprises a number of fabric layers and one layer of core.

In yet another preferred embodiment, the first plurality of spar cap preformed parts, the second plurality of blade root preformed parts, and the third plurality of aerodynamic fairing preformed parts comprises preformed parts that are not blade-specific and that further can be used to manufacture multiple products.

In one more preferred embodiment, the shell structure inlcudes at least one shear web structure enclosed within, internally coupled to the shell structure and configured to provide structural integrity to the shell structure.

According to a second aspect of the present invention, there is provided a method of manufacturing a wind turbine blade. The method includes processing a number of preformed parts into a collection of prefabricated laminates and assembling the collection of prefabricated laminates to build a shell structure defining a leading edge and a trailing edge.

According to the invention, the assembling the collection of prefabricated laminate includes assembling a first plurality of spar cap preformed parts to build a first plurality of spar cap laminates, assembling a second plurality of blade root preformed parts to build a second plurality of blade root laminates, assembling a third plurality of aerodynamic fairing preformed parts to build a third plurality of aerodynamic fairing laminates, assembling said first plurality of spar cap laminates, said second plurality of blade root laminates and said third plurality of aerodynamic fairing laminates to build said upwind shell and said downwind shell. Preferably, each of the first plurality of spar cap preformed parts, the second plurality of blade root preformed parts, and the third plurality of aerodynamic fairing preformed parts has a mass less than <NUM>.

In one more preferred embodiment, the method includes providing structural integrity to said shell structure by internally coupling and enclosing at least one shear web structure within said shell structure.

Various other features will be apparent from the following detailed description and the drawings.

An example of the present invention will now be described with reference to the following drawings in which:.

This invention includes embodiments that relate to wind turbines and more specifically to wind turbine rotors or blades. However, it is readily applicable to other types of wind-exposed aerofoil surfaces negotiating aerodynamic forces, resistance and aerodynamics, such as helicopter rotor blades, or fan blades.

One skilled in the art will recognize that it is possible to make sections of the wind turbine blade with one or more easily controllable and constructible, very small preformed parts. The parts are of a size that they no longer need large cranes to move them around and therefore can be moved around and placed into the mold by much faster and agile means than large cranes.

The parts are also designed such that they can be 'preformed' away from the main blade mold (preforming refers to the deposition of a number of layers into each part).

This helps in many ways. First, there is less likelihood of defects such as wrinkles, as the basic building blocks are smaller and more controllable. Second, the relatively smaller size of the typical preformed parts means that the blade manufacturing process can be more easily automated, thereby reducing labor and also increasing quality and deposition rate. Third, it opens up the possibility to preform the materials flat which means that they can be efficiently transported. This means that they could be preformed in another location and at another time and cost effectively transported to the final blade factory. Finally, the preforming process allows a number of more cost effective material types to be used that are cheaper and structurally more efficient.

The preformed parts typically consist of <NUM>-<NUM> layers of fabric which will be tapered at the ends and can be held together with adhesive, stitching or rivets. A significant number of identical preform parts can be used in the blade. This helps to reduce cost by driving standardization.

In operation, the preformed parts are then picked up, conveyed to the blade mold and then placed in the blade mold to the right accuracy. When the parts are placed into the mold they change shape and conform to the local shape of the mold. In one further embodiment of the invention, wherein the spar cap preformed parts, the blade root preformed parts, and the aerodynamic fairing preformed parts are not blade-specific and that further can be used to manufacture multiple different blade parts, products or components.

In one embodiment of the invention, each of the plurality of preformed parts has a mass less than <NUM> and preferably less than <NUM>. In another embodiment of the invention, each of the plurality of preformed parts is less than <NUM> in length and preferably less than <NUM> in length, so that the preform parts can fit in a shipping container.

In yet another embodiment of the invention, each of the plurality of preformed parts is created flat and configured to take a shape of the blade when assembled in plurality. In one further embodiment of the invention, each of the plurality of preformed parts forming the spar cap laminate has tapered ends.

In one embodiment of the invention, more than <NUM>% and more preferably <NUM>% of the plurality of preformed parts of each type, in other words spar cap laminate preforms, root laminate preforms, and aerodynamic fairing laminate preforms, are identical. In another embodiment of the invention, each of the plurality of preformed parts forming the spar cap laminate comprises predominantly less than <NUM>% and preferably less than <NUM>% unidirectional (UD) fiber. In one further embodiment of the invention, each of the plurality of preformed parts forming the root laminate comprises <NUM>% UD fiber and <NUM>% +/-<NUM> fiber.

In one embodiment of the invention, each of the plurality of preformed parts comprises either thermosetting or thermoplastic resin and further wherein each of the plurality of preformed parts comprises no fiber, short fiber or continuous fiber.

In another embodiment of the invention, each of the plurality of preformed parts forming the aerodynamic fairing comprises predominantly +/-<NUM> fiber and a core. In yet another embodiment of the invention, each of the plurality of preformed parts forming the aerodynamic fairing comprises a number of fabric layers and one layer of core.

<FIG> illustrates a cross-sectional view <NUM> of the wind turbine blade <NUM> of <FIG>. Blade <NUM> includes downwind shell <NUM> and upwind shell <NUM> joined along a first longitudinal edge (leading edge) <NUM> and a second longitudinal edge (trailing edge) <NUM> to constitute a complete and closed shell structure <NUM>. A typical shear web structure <NUM> including flanges, is enclosed within and internally coupled to the shell structure. The shear web structure <NUM> supports and provides structural integrity to the shell structure <NUM>.

<FIG> illustrates a perspective view of the wind turbine blade of <FIG>. Referring to <FIG>, first and second spar cap laminates <NUM> and <NUM> are attached to blade segment <NUM>. The first and second spar cap laminates <NUM> and <NUM> are configured to form an exemplary joint such as a scarf joint. The blade segment <NUM> is a hollow segments comprising outer skin <NUM>. The skin is made from materials that is light-weight and strong. The spar cap <NUM> bear longitudinal-loads experienced by the wind turbine blades and are attached to the inside of the skin of the blade segments. The wind turbine blade <NUM> also includes a bulkhead <NUM> at the intersection of the blade segments. The bulkhead <NUM> further increases the structural strength of the wind turbine blade. Spar cap laminates <NUM> and <NUM> typically include a material such as fiberglass or carbon composites that are strong and capable of withstanding longitudinal loads.

Referring to <FIG>, <FIG>, and <FIG>, the bulkhead <NUM> is at the connection between outer skins of the first and second blade segments. A first portion of the flange of the bulkhead is bonded to the inside surface of the outer skin of the blade segment <NUM>. The bulkhead <NUM> includes a leading edge bulkhead and a trailing edge bulkhead separated by a gap to accommodate a shear web <NUM> (<NUM> in <FIG>) for connecting the spar cap <NUM>. The center portion of the bulkhead is represented by the sides of the leading edge bulkhead and the trailing edge bulkhead that face each other and is configured to accommodate the spar cap laminates <NUM> and <NUM> by including recesses dimensioned to receive the spar cap laminates <NUM> and <NUM>. The bulkhead typically comprises materials such as fiberglass or carbon composite. The thickness of the bulkhead is typically <NUM>-<NUM>.

As shown in the embodiment of <FIG>, <FIG>, and <FIG>, the spar cap laminates <NUM> and <NUM> include tapered and non-tapered sections, and a distance between the two tapered sections remains substantially constant along the length of the tapered sections. As used herein, substantially constant typically means plus or minus <NUM> percent of the average gap. The shear web <NUM> of the spar cap laminates <NUM> and <NUM> connects the non-tapered sections of the first spar cap <NUM>. The second spar cap <NUM> also includes tapered and non-tapered sections. The alignment occurs over the tapered sections of the first and second spar cap segments. Specifically, the outer sides of the tapered sections of the first spar cap <NUM> are straight while the inner sides are tapered till the end. The inner sides of the tapered sections of the second spar cap <NUM> are straight while the outer sides are tapered till the end. To form the alignment, the tapered inner sides of the first spar cap segments are positioned over the tapered outer sides of the second spar cap segments. This typically forms a scarf joint, as a non-limiting example. In a further example, the length of the tapered section is <NUM> to <NUM> times greater than the thickness of the non-tapered section for both the first and the second spar cap segments.

Referring to <FIG> and <FIG>, in one embodiment of the invention, the preformed parts are bonded together with bonding elements to form the wind turbine shell structure. In one embodiment of the invention the bonding elements or the adhesive means is a one or two-component adhesive such as epoxy, polyurethane or methacrylate adhesives and it is possible to create a bonding particularly durable in relation to the different kind of weather conditions a wind turbine blade is exposed to.

The different preformed parts are typically adapted to the section of the wind turbine blade they cover. Especially, the widths of the preformed parts vary in order to meet the different dimensions of the wind turbine blade at different positions e.g. the width at the root compared to the width at the tip. The height of the preformed parts, and thus the side-to-side length of the preformed parts, may also vary in order to meet the above-mentioned different dimensions of the wind turbine blade.

In a preferred embodiment, a preformed part preferably includes a width and height ranging between <NUM> and <NUM> meter in width and between <NUM> and <NUM> meter in height, corresponding to the shape of different parts of the wind turbine blade and has a thickness range between <NUM> and <NUM> preferably between <NUM> and <NUM> e.g. <NUM> at or close to the ends of the lip sections and <NUM> at the center of the preformed part. Further, the ends may advantageously be rounded in order to establish a smoother crossing to the wind turbine blade and in a preferred embodiment the adhesive layer is between <NUM> and <NUM> such as <NUM>.

Referring to <FIG>, <FIG>, and <FIG>, shear web structures <NUM> typically include spar cap laminates mutually connected by two plates. The wind turbine blade shells and beam may be made in glass fiber reinforced plastics (GRP) i.e. glass fiber reinforced polyester or epoxy. However, other reinforcing materials may be used such as carbon fiber or aramid (Kevlar). Wood, wood-epoxy, wood-fiber-epoxy or similar composites may also be used as wind turbine blade materials.

In a preferred embodiment, a preformed part may typically be made of a number of materials or combinations of materials by several production methods. For instance, in a preferred embodiment the preformed part is made in plastic by an injection molding machine. In another embodiment casting in a mold is used to create the preformed part in glass fiber material or a similar fiber material such as carbon fiber or aramid material reinforcing an epoxy or polyester resin. Further, the preformed part may be manufactured in a thin metal plate e.g. in a rolled metal with the distance means welded or adhered to the plate. The metals are preferably chosen among the lighter metals such as aluminum. The preformed part may also be made of different materials such as a plastic plate with rubber distance means.

<FIG> illustrates a cross-sectional view <NUM> of the root region of the wind turbine blade of <FIG>. <FIG> illustrates a cross-sectional view <NUM> of the root laminate <NUM> and the root region of the wind turbine blade of <FIG>. <FIG> illustrates an alternative cross-sectional view <NUM> of the root laminate <NUM> and the root region of the wind turbine blade of <FIG>.

Most modern day wind turbine blades are manufactured with either carbon or glass fiber reinforced plastic. As is well known in the art, at the root (hub) end of the blade, this is typically glass fiber combined with epoxy resin (and sometimes polyester, vinyl ester and polyurethane resin families). The typical manufacturing methods are vacuum resin infused or prepreg methods.

The thickness of the laminate <NUM> required at the root end can be very high when compared to some other parts of the wind turbine blade and is often in the range of <NUM>-<NUM> thick but with more modern blades can be up to <NUM> thick. This high thickness can cause manufacturing problems. When the resin system is curing, it generates heat in an exothermic reaction. In the thick areas of the root, the heat generated can become so much that it causes damage with the finished component such that it cannot be used.

A typical method of forming the root end is shown in <FIG>, <FIG> and <FIG>. In this, the matrix of dry fabric is laid up in the mold of a suitable shape. The resin is then infused and cured to the finished part as shown in <FIG>. Once the root component of the blade is cured, it is then typically transferred to a drilling location where a number of holes <NUM> are drilled in the end of the root laminate to allow metal root inserts with female screw threads to be bonded or mechanically fixed in place. Two semi-circular subassemblies are then joined together to make the finished root end joint as shown in <FIG>.

As illustrated in the figures, the first preformed part <NUM> may start at the root of the wind turbine blade and the last preformed part end at the tip of the blade, creating a continuous line of preformed parts each covering a section of the blade. However, the preformed parts may also start and end at other positions, e.g. start and end at some distance from the root and the tip.

Further, one or more preformed parts may cover different sections of the wind turbine blade, e.g. a section at the center and the root of the blade with an uncovered section in between or simply one preformed part covering one section of the blade. The preformed parts are preferably adapted to form an aerodynamic profile with the wind turbine blade in relation to the wind.

A number of segments as shown in <FIG>, <FIG>, and <FIG> are used to construct a root end joint by a wind turbine. Each of the segments has a connection end into which a plurality of holes is formed and an opposite end. The segment has the general shape of segment of a hollow cylinder which tapers in thickness from the connection end to the opposite end. In general, it is intended that <NUM> segments (<NUM> in each half) will be connected together to form the complete the root end. In this case, each segment will subtend an angle of <NUM>° at the center of the hub.

However, there may be as few as <NUM> such segments (<NUM> in each half) subtending an angle of <NUM>°, or more than <NUM> segments for larger blades which will subtend a correspondingly smaller angle. On each side of the segment, typically there is a key <NUM>, <NUM> designed to locate and interlock with the corresponding key on an adjacent segment.

Typically, each segment will be <NUM> long and <NUM> wide. At the connection end, there is a significant amount of uni-directional fiber with a small percentage of bi-axial fiber. The amount of fiber moves towards the opposite end <NUM> where it ends up being <NUM> ply layer thick. Depending on its application (infusion or prepreg blade root), the root segment is made in one of two ways.

For an infusion blade, it can be made by wet lamination with vacuum, vacuum resin infusion, resin transfer molding or similar process. The first layers of the fiber are laid into the tool, then metallic inserts or tubular spacers are placed into the tool and held in position with an alignment frame at the end of the tool. The alignment frame allows the accurate positioning of the inserts. The final layers of fiber are then placed into the tool. The whole lay-up is then placed under vacuum and the resin is either infused or injected and then fully cured.

For a prepreg blade, the process is very similar, except that layers of prepreg are inserted into the tool instead of the layers of fiber. The prepreg layup is then placed under vacuum and partially cured such that it becomes a semi-cured preform.

Alternatively, the segments can be made without the inserts or spacers <NUM> and the holes are drilled in a subsequent step in a separate jig. Once the individual root segments are made, they can undergo a quality assurance process to assess the structural integrity of the segments and also to assess the integrity of the inserts. The inserts may be conventional metallic inserts that are well known in the art. Alternatively, they may be the inserts disclosed in our earlier <CIT>.

The assembly of the root end joint is shown in <FIG>, <FIG>, and <FIG>. In <FIG>, four segments are shown to make up one half of the root end joint. In practice, there will typically be eight. The segments are placed in a tool having a generally semi-circular configuration prior to any other laminate being placed into the tool. The root end of the insert is connected to an alignment frame and are bolted in place using bolts <NUM>. This ensures that the alignment of the bolt circle is maintained during the manufacturing process. In step b), once the segments are accurately positioned, the rest of the blade laminate is laid up. The laminate effectively forms a very long scarf joint with the tapering laminate in the root segment. Once all of the laminate has been laid up, the blade is placed under vacuum and is infused with resin (if it is an infusion blade) or is simply cured (if it is a prepreg blade). The blade half is then complete ready for final assembly of the two blade halves as normal.

<FIG> is a cross-sectional view <NUM> of an aerodynamic fairing of the wind turbine blade of <FIG>. Referring to <FIG>, aerodynamic fairing laminate <NUM> is shown. The aerodynamic fairing laminate <NUM> is formed from a fairing <NUM> and a preform <NUM> fixed to an outer surface <NUM> of the fairing <NUM> at the leading edge <NUM> of the fairing laminate <NUM>.

Referring to <FIG>, the preform <NUM> comprises a thermoplastic film outer layer fused to a fiber substrate. The thermoplastic film is formed from an aliphatic polyurethane, which is approximately <NUM> microns thick and may be produced using long and short chain polyether, polyester, or caprolactone glycols. The polyether types have better hydrolytic stability and low-temperature flexibility, the polyester types have better mechanical properties, and caprolactones offer a good compromise between the properties of the polyether and polyester types. In this example, caprolactone glycols are used. This results in film having a Shore A hardness of approximately <NUM> to <NUM>, an elongation of at least <NUM>% and a surface energy in the region of <NUM> to <NUM> mN/m. The fiber substrate is a glass fiber fabric preform which is multiaxial and has a weight of approximately <NUM>/m2.

In operation, the preform <NUM> is placed into a mold with the thermoplastic film against the surface of the mold. Following this, layers of prepreg, which are formed from glass or carbon fibers pre-impregnated with an epoxy resin, are placed onto the preform <NUM> to form the typical composite laminate required for a fairing.

The preform <NUM> and the layers of prepreg are then co-cured under a vacuum and at a temperature of between <NUM> to <NUM>° C. for approximately <NUM> hours in the same manner as for normal prepreg processing. As the stack of the layer <NUM> and the layers of prepreg is cured, resin from the prepreg migrates into and impregnates the fiber substrate. The resin then fully cures to form the fairing <NUM> from the prepreg and to fix the preform <NUM> to the composite body <NUM>. In doing so, the resin forms a continuous matrix through the composite body <NUM> and the preform <NUM> to firmly bond the two layers together. The resin also forms a chemical connection with the thermoplastic film, further strengthening the fixation of the preform <NUM> to the composite body <NUM>. Thus, the resulting interface between the fairing <NUM> and the preform <NUM> is well controlled and the fairing <NUM> and fiber substrate provide a very high quality substrate directly beneath the thermoplastic film.

Since the fairing <NUM> and the preform <NUM> are co-cured, the fairing <NUM> is shaped around the preform <NUM> so that the edges of the preform <NUM> lie flush with the fairing <NUM>. This gives the resulting fairing laminate <NUM> a smooth outer profile, as shown in <FIG>. This smooth profile reduces the impact of the preform <NUM> on aerodynamic performance and avoids presenting free edges which could otherwise lead to the preform <NUM> being more easily removed from the fairing <NUM>.

<FIG> is a side and cross-sectional view of the main laminate of the wind turbine blade of <FIG>. <FIG> is a cross-sectional view of the spar cap laminates <NUM> and <NUM> (<FIG>), root laminate <NUM> (<FIG>) and the aerodynamic fairing laminate <NUM> in accordance with one embodiment of the wind turbine blade of <FIG>. <FIG> is a cross-sectional view of the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> in accordance with an alternative embodiment of the wind turbine blade of <FIG>.

In one embodiment of the invention, the preform components may be constructed of a continuous fibrous material, organic or inorganic, and impregnated with resin, such as epoxy, vinyl-ester, polyester, or the like as is known in the art. Referring to <FIG>, the fibrous material of the preform component <NUM> may have a woven configuration and may be constructed from, for example, carbon, glass, synthetic material, or the like as is known in the art. The preform component <NUM> may have a length shorter than the desired length of the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> and, therefore, multiple preform components <NUM> may be attached together to form the entire spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM>.

Each preform component <NUM> may typically have a swept contour so that when they are assembled together to form the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> they will have the desired swept shape, or banana shape, following the shape of a swept-shaped rotor blade. It should also be appreciated that the preform component <NUM> may be substantially straight and may be used to assemble a substantially straight spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> in the same manner as just described. The preform component <NUM> may have a first angled end forming an obtuse angle with the top side of the preform component <NUM>. The preform component may have a second angled end, opposite the first angled end, forming an acute angle with the top side of the preform component <NUM>. The second angled end may be formed at a supplementary angle to the angle of the first angled end. When attaching multiple preform components <NUM> together, the first angled end of a first preform component <NUM> may align and mate with the second angled end of a second preform component <NUM>, forming a scarf joint.

In operation, multiple preform components may be attached to form the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM>. The first preform component <NUM>, having the first angled end, may be mated with the second preform component <NUM>, having the second angled end, placing an intervening joint interface layer in between the two angled ends, and creating an exemplary and non-limiting scarf joint. The joint interface layer may be a polymer material and may further include a fiber substrate, such as fiberglass or the like as is known in the art. One or more pins may be inserted through the mated scarf joint. The pins may be constructed from a rigid material such as a sturdy metal; however, the pins need not be metallic. Further, the pins need not be cylindrical in shape, but may be any shape that will form continuous contact through the scarf joint and the first and second preform component <NUM>, such as a flat sheet, a ridged sheet, or the like. The pins further strengthen the scarf joint in the out-of-plane direction while also maintain alignment between the contiguous preform components <NUM> while forming the entire spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM>.

In another exemplary embodiment of the invention multiple preform components may have one or more facing plies on at least one side of the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> and covering the scarf joints. The facing plies may be a polymer material and may further include a fiber substrate, such as fiberglass or the like as is known in the art. The facing plies, like the pins, further strengthen the scarf joint and maintain alignment between the contiguous preform components <NUM>. It is appreciated that while the facing plies on only one side of the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> the facing plies may be applied to either or both sides of the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM>. It is also contemplated that multiple preform components <NUM> may be joined in a side-by-side configuration as well as an end-to-end configuration. In this embodiment, the sides of each preform component <NUM> may have supplementary acute and obtuse angles so a scarf joint, like that described above, may be formed between the preform components <NUM> sitting side-by-side as well as end-to-end.

In operation, an appropriate molding tool may be used to fabricate the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> from multiple preformed components <NUM>. Because the preform components <NUM> may be flat when first received from the manufacturer, the molding tool may be used to form the preform components <NUM> into an arcuate, rather than flat, shape. The arcuate shape will follow the arc of the rotor blade from the leading edge to the trailing edge as is shown in <FIG>. The molding tool includes a convex form with a surface having a convex curve following the arcuate shape of the first shell or the second shell of the rotor blade. To form the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM>, multiple preform components <NUM> may be laid over the convex form and aligned end-to-end.

The convex form also may include one or more alignment fences that will communicate with one side of the preform components <NUM> when laid on the convex form, further maintaining alignment of the contiguous preform components <NUM>. In an exemplary embodiment, one alignment fence, or a series of alignment fences, are placed on each side of the convex form and opposite each other to hold the preform components <NUM> in place. Finally, the alignment fence may include alignment markings along the length of the fence to identify where to align each of the preform components <NUM>. In one embodiment of the present invention, two different molding tools may be employed, whereby a first molding toot includes the convex mold form having the shape of the first shell forming the top skin of the rotor blade and whereby a second molding tool includes the convex mold form having the shape of the second shell forming the bottom skin of the rotor blade.

After final construction and integration with the rotor blade, spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> may include multiple preform components <NUM> lying end-to-end and attached by the scarf joint. It should be appreciated that the width of the multiple preform components <NUM> may not be the same, allowing the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> to narrow at one or both ends and remain wider in the middle sections. Further, the thickness of the multiple preform components <NUM> may not be the sane, allowing for the spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> to taper in thickness at one or both ends and remain thicker in the middle sections. It should further be appreciated that, any number of the preform components <NUM> may be used to achieve the necessary length and the desired swept shape contour, considering the size and availability of the preform components <NUM>. Additionally, whereas <FIG> show a swept-shaped spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM>, it should be appreciated that a generally straight-shaped spar cap laminates <NUM>, <NUM>, root laminate <NUM> and the aerodynamic fairing laminate <NUM> may be formed from multiple preform components <NUM> not having a curved shape.

It should be apparent that the foregoing relates only to exemplary embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.

<FIG> illustrates a flow chart of a method <NUM> of manufacturing a wind turbine blade including a preferred embodiment of a preformed part according to the invention. The manufacturing method <NUM> includes the steps: joining (<NUM>) at least one upwind shell and at least one downwind shell along a first longitudinal edge and a second longitudinal edge to form a shell structure; making a spar cap laminate (<NUM>) from a plurality of preformed parts; making a root laminate (<NUM>) from a plurality of preformed parts; making an aerodynamic fairing laminate (<NUM>) from a plurality of preformed parts; assembling (<NUM>) the spar cap laminate, the root laminate and the aerodynamic fairing laminate into the shell structure and enclosing and internally coupling (<NUM>) the shear web structure.

A technical contribution for the disclosed method and apparatus is that it provides for a wind turbine blade made from a number of preformed parts that can be made at a different places at different times and assembled together. The technical contribution also includes a method of manufacturing the wind turbine blade from a number of preformed parts that can be made at a different places at different times.

According to one aspect of the present invention, there is provided a wind turbine blade including a shell structure defining a leading edge and a trailing edge, and an upwind shell and a downwind shell joined along at least one of the leading edge or the trailing edge. The shell structure includes an assembly of preformed parts processed into a collection of prefabricated laminates.

Claim 1:
A wind turbine blade (<NUM>) comprising:
a shell structure (<NUM>) defining a leading edge (<NUM>) and a trailing edge (<NUM>); and
an upwind shell (<NUM>) and a downwind shell (<NUM>) joined along at least one of: said leading edge or said trailing edge, wherein said shell structure comprises a root laminate (<NUM>) made from a second plurality of blade root preformed parts, characterized in that the shell structure comprises:
a spar cap laminate (<NUM>, <NUM>) made from a first plurality of spar cap preformed parts, and
an aerodynamic fairing laminate (<NUM>) made from a third plurality of aerodynamic fairing preformed parts.