System and method for pitching rotor blades

Abstract

A system and method for variable pitch of rotor blades. A wind turbine includes a hub rotatable about an axis and a blade coupled to the hub. The blade includes an inner blade portion having a first end and a second end. The inner blade portion is coupled to the hub at the first end and extends radially outward from the hub to the second end. The blade also includes an outer blade portion having a first end and a second end. The first end of the outer blade portion is pivotally coupled to the second end of the inner blade portion.

Description

Technical Field

[0001] The field of the present disclosure relates to wind turbines, and more particularly to systems for pitching rotor blades of wind turbines. Background Art

[0002] At least some known wind turbines include a rotor with multiple blades. The rotor is sometimes coupled to a housing or nacelle, which is positioned atop a base (e.g., a tubular tower). At least some known utility-grade wind turbines (i.e., wind turbines designed to provide electricity to a utility grid) have rotor blades of predetermined shape and size. The rotor blades convert the kinetic energy of the wind into aerodynamic forces on the blades, which induce mechanical rotational torque to drive one or more generators, thereby generating electricity.

[0003] Wind turbines are exposed to large variations in wind inflow, which apply varying loads to the wind turbine structure, particularly the wind turbine rotor and shaft. Some known wind turbines include a pitch mechanism designed to pitch the rotor blades relative to the casing based on various factors, such as wind speed and the rotational speed of the rotor. Pitching the rotor blades refers to rotating the blades to change the angle of attack of the wind on the blades. In at least some wind turbine systems, pitching the rotor blades to a desired angle of attack can induce stress and fatigue on components of the wind turbine system, such as, for example, pitch bearings located at the root of the blades. Furthermore, at least some rotor blades are generally formed as a single-piece blade. As a result, transportation of such rotor blades generally requires that the rotor blades be transported in a container that can accommodate the entire length of the rotor blade.

[0004] Therefore, it is desirable to provide a wind turbine system that reduces stress and fatigue on components of the wind turbine system during operation.Furthermore, it is desirable to provide a rotor blade that allows for more compact and therefore less expensive transportation of the rotor blade. Summary of the Invention

[0005] In one aspect, a wind turbine is provided. The wind turbine includes a hub rotatable about an axis and blades coupled to the hub. The blades include an inner blade portion having a first end and a second end. The inner blade portion is coupled to the hub at the first end and extends radially outward from the hub to the second end. The blades also include an outer blade portion having a first end and a second end. The first end of the outer blade portion is pivotally coupled to the second end of the inner blade portion.

[0006] In another aspect, a blade for use in a wind turbine system is provided. The blade includes an inner blade portion, an outer blade portion, and a rotatable element. The inner blade portion has a first end and a second end. The outer blade portion includes a first end and a second end. The first end of the outer blade portion is coupled to the second end of the inner blade portion. The rotatable element extends between the inner and outer blade portions. The rotatable element includes a first end coupled to the inner blade portion and a second end coupled to the outer blade portion. The second end of the rotatable element is rotatable relative to the first end of the rotatable element to facilitate rotation of the outer blade portion relative to the inner blade portion.

[0007] In yet another aspect, a method of assembling a blade for use in a wind turbine system is provided. The blade includes an inner blade portion having a first end and a second end. The blade also includes an outer blade portion having a first end and a second end. The method includes coupling the first end of the outer blade portion to the second end of the inner blade portion. The method also includes providing a rotatable element having a first end and a second end, the second end of the rotatable element being rotatable relative to the first end of the rotatable element. The method also includes coupling the first end of the rotatable element to the inner blade portion. The method also includes coupling the second end of the rotatable element to the outer blade portion such that the outer blade portion is rotatable relative to the inner blade portion.

[0008] Technical Solution 1. A wind turbine comprising:

[0009] a hub rotatable about an axis; and

[0010] a blade coupled to the hub and comprising:

[0011] an inner blade portion including a first end and a second end, the inner blade portion being coupled to the hub at the first end and extending radially outward from the hub to the second end; and

[0012] An outer blade portion includes a first end and a second end, the first end of the outer blade portion being pivotally coupled to the second end of the inner blade portion.

[0013] Technical Solution 2. A wind turbine according to Technical Solution 1, characterized in that the blade defines a longitudinal axis extending from the first end of the inner blade part to the second end of the outer blade part, wherein the outer blade part is configured to rotate around the longitudinal axis relative to the inner blade part.

[0014] Technical Solution 3. A wind turbine according to Technical Solution 1, characterized in that the blade defines a longitudinal axis extending from the first end of the inner blade part to the second end of the outer blade part, wherein the first end of the inner blade part is pivotally connected to the hub so that the inner blade part is configured to rotate about the longitudinal axis.

[0015] Technical Solution 4. The wind turbine according to Technical Solution 1, wherein the outer blade portion extends obliquely relative to the inner blade portion.

[0016] Technical Solution 5. The wind turbine according to Technical Solution 1 is characterized in that it also includes a rotatable element extending between the inner blade part and the outer blade part, the rotatable element including a first end connected to the inner blade part and a second end connected to the outer blade part.

[0017] Technical Solution 6. The wind turbine according to Technical Solution 5 is characterized in that the second end of the rotatable element is rotatable relative to the first end of the rotatable element to facilitate rotating the outer blade part relative to the inner blade part.

[0018] Technical Solution 7. The wind turbine according to Technical Solution 5 is characterized in that the rotatable element is an elastic flexure bearing.

[0019] Technical Solution 8. The wind turbine according to Technical Solution 7, wherein the second end of the rotatable element is rotatable by at least + / - 1 degree relative to the first end of the rotatable element.

[0020] Technical Solution 9. The wind turbine according to Technical Solution 5 is characterized in that it also includes a support structure positioned within the inner blade part, and the rotatable element also includes a main body extending from the support structure to the length of the outer blade part, wherein the main body is configured to elastically deform around the length of the main body.

[0021] Technical Solution 10. The wind turbine according to Technical Solution 9, wherein the main body comprises a plurality of rods, each of the plurality of rods extending from the support structure to the outer blade portion.

[0022] Technical Solution 11. The wind turbine according to Technical Solution 1 is characterized in that it also includes a plurality of cables extending between the inner blade part and the outer blade part, and the plurality of cables are configured to stabilize the positioning of the outer blade part relative to the inner blade part and drive the pitch change of the outer blade part.

[0023] Technical Solution 12. A blade for use in a wind turbine system, comprising:

[0024] an inner blade portion comprising a first end and a second end;

[0025] an outer blade portion comprising a first end and a second end, the first end of the outer blade portion being coupled to the second end of the inner blade portion; and

[0026] a rotatable element extending between the inner blade portion and the outer blade portion, the rotatable element including a first end coupled to the inner blade portion and a second end coupled to the outer blade portion, wherein the second end of the rotatable element is rotatable relative to the first end of the rotatable element to facilitate rotating the outer blade portion relative to the inner blade portion.

[0027] Technical Solution 13. The blade according to Technical Solution 12 is characterized in that the rotatable element is an elastic flexure bearing.

[0028] Technical Solution 14. The blade according to Technical Solution 13 is characterized in that the second end of the rotatable element can rotate at least + / - 1 degree relative to the first end of the rotatable element.

[0029] Technical Solution 15. The blade according to Technical Solution 12 is characterized in that it further includes a support structure positioned within the inner blade portion, and the rotatable element further includes a flexible support member extending from the support structure to the outer blade portion.

[0030] Technical Solution 16. A method of assembling a blade for use in a wind turbine system, the blade comprising an inner blade portion having a first end and a second end and an outer blade portion having a first end and a second end, the method comprising:

[0031] coupling the first end of the outer blade portion to the second end of the inner blade portion;

[0032] coupling a first end of a rotatable element to the inner blade portion; and

[0033] The second end of the rotatable element is coupled to the outer blade portion such that the outer blade portion is rotatable relative to the inner blade portion.

[0034] Technical Solution 17. The method according to Technical Solution 16 is characterized in that the rotatable element is an elastic flexure bearing.

[0035] Technical Solution 18. The method according to Technical Solution 17 is characterized in that the second end of the rotatable element can rotate at least + / - 1 degree relative to the first end of the rotatable element.

[0036] Technical Solution 19. The method according to Technical Solution 17 is characterized in that it also includes positioning a support structure within the inner blade portion, wherein the first end connecting the rotatable element also includes connecting the flexible support member of the rotatable element to the support structure, and wherein the second end connecting the rotatable element also includes connecting the flexible support member to the outer blade portion.

[0037] Technical Solution 20. The method according to Technical Solution 16 is characterized in that it also includes connecting an actuating mechanism to at least one of the inner blade part and the outer blade part, and the actuating mechanism is configured to drive the outer blade part to rotate relative to the inner blade part. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings, in which like numerals refer to like parts throughout the several views, and in which:

[0039] Figure 1 is a perspective view of an exemplary wind turbine;

[0040] Figure 2 is used in Figure 1 A schematic cross-sectional view of an exemplary rotor blade for use in a wind turbine is shown;

[0041] Figure 3 is used in Figure 1 An enlarged schematic cross-sectional view of an alternative rotor blade for use in a wind turbine is shown;

[0042] Figure 4 yes Figure 3 a schematic end view of a portion of an alternative rotor blade is shown;

[0043] Figure 5 is used in Figure 1 A schematic cross-sectional view of a further alternative rotor blade for use in a wind turbine is shown;

[0044] Figure 6 is used in Figure 1 a schematic cross-sectional view of yet another alternative rotor blade for use in a wind turbine as shown; and

[0045] Figure 7 is assembled for use in Figure 1A flow chart of an exemplary method for use with a rotor blade in a wind turbine is shown.

[0046] Unless otherwise indicated, the drawings provided herein are intended to illustrate features of the embodiments of the present disclosure. These features are believed to be applicable in a wide variety of systems that include one or more embodiments of the present disclosure. As such, the drawings are not intended to include all conventional features known to those of ordinary skill in the art necessary to practice the embodiments disclosed herein. DETAILED DESCRIPTION

[0047] In the following description and claims, reference will be made to a number of terms which shall be defined to have the following meanings.

[0048] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0049] As used herein, the term "blade" is intended to represent any device that provides a reactive force when moved relative to a surrounding fluid. As used herein, the term "wind turbine" is intended to represent any device that generates rotational energy from wind energy and, more specifically, converts kinetic energy of wind into mechanical energy.

[0050] "Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

[0051] As used herein throughout the specification and claims, approximating language may be used to modify any quantitative representation that is permissibly variable without resulting in a change in the basic function to which it relates. Thus, a value modified by one or more terms such as "about," "approximately," and "substantially" is not limited to the precise value specified. In at least some cases, approximating language may correspond to the precision of an instrument used to measure a value. Here and throughout the specification and claims, range limitations may be combined and / or interchanged, and such ranges are identified and include all subranges contained therein unless context or language indicates otherwise.

[0052] Embodiments described herein relate to a wind turbine and a rotor blade for a wind turbine. The wind turbine includes a hub rotatable about an axis and a rotor blade coupled to the hub. The rotor blade includes an inner blade portion having a first end and a second end. The inner blade portion is coupled to the hub at the first end and extends radially outward from the hub to the second end. The rotor blade also includes an outer blade portion having a first end and a second end. The first end of the outer blade portion is pivotally coupled to the second end of the inner blade portion. Thus, the wind turbine and rotor blade described herein facilitate pitching the outer blade portion of the rotor blade relative to the inner blade portion of the rotor blade. As a result, the wind turbine and rotor blade described herein reduce the load on a pitch bearing located at the root of the rotor blade during pitching of the outer blade portion, thereby extending the service life of the pitch bearing located at the root and reducing maintenance costs of the wind turbine and rotor blade. Furthermore, the inner and outer blade portions of the rotor blade described herein can be disassembled for transportation, thereby allowing for more compact transportation of the rotor blade and thereby reducing the costs associated with transporting the rotor blade.

[0053] Figure 1 1 is a schematic perspective view of an exemplary wind turbine 100. In the exemplary embodiment, wind turbine 100 is a horizontal-axis wind turbine. Wind turbine 100 includes a tower 102 extending from a support surface (not shown), a nacelle 106 coupled to tower 102, and a rotor 108 coupled to nacelle 106. Rotor 108 has a rotatable hub 110 and a plurality of rotor blades 112 coupled to rotatable hub 110. In the exemplary embodiment, rotor 108 has three rotor blades 112. In alternative embodiments, rotor 108 has any number of rotor blades 112 that enables wind turbine 100 to function as described herein. In the exemplary embodiment, tower 102 is fabricated from tubular steel and has a cavity ( Figure 1 ). In alternative embodiments, wind turbine 100 includes any tower 102 that enables wind turbine 100 to operate as described herein. For example, in some embodiments, tower 102 is any of a lattice steel tower, a guyed tower, a concrete tower, and a hybrid tower.

[0054] In the exemplary embodiment, blades 112 are positioned about rotatable hub 110 to facilitate rotating rotor 108 when wind flows through wind turbine 100. As rotor 108 rotates, kinetic energy from the wind is converted into usable mechanical energy and subsequently into electrical energy. During operation, rotor 108 rotates about a horizontal axis 116 that is substantially parallel to a supporting surface. Additionally, in some embodiments, rotor 108 and nacelle 106 rotate about tower 102 on a yaw axis 118 to control the orientation of blades 112 relative to the direction of the wind. In alternative embodiments, wind turbine 100 includes any rotor 108 that enables wind turbine 100 to operate as described herein.

[0055] Figure 2 is used in a wind turbine 100 (in Figure 1 A schematic cross-sectional view of an exemplary rotor blade 112 for use in a rotary hub 110 is shown in FIG. In the exemplary embodiment, the rotor blade 112 is configured to be coupled to the rotatable hub 110 ( FIG. 1 ) at the hub end 120. Figure 1 1 and extends radially outward from rotatable hub 110 to distal end 122. Rotor blade 112 defines a longitudinal axis 124 extending between hub end 120 and distal end 122 of rotor blade 112. In the exemplary embodiment, hub end 120 includes a hub pitch mechanism 126 for coupling rotor blade 112 to rotatable hub 110 (at Figure 1 When the rotor blades 112 are coupled to the rotatable hub ( Figure 1 1 ), hub pitch mechanism 126 facilitates rotating rotor blades 112 relative to rotatable hub 110 about longitudinal axis 124 (i.e., pitching rotatable blades 112). In an exemplary embodiment, hub pitch mechanism 126 includes a hub actuation mechanism, such as, for example and without limitation, a hub bearing (not shown) and a gear and pinion actuation mechanism. In an alternative embodiment, rotor blades 112 include a hub actuation mechanism for connecting rotor blades 112 to rotatable hub 110 (i.e., pitching wind turbine 100). Figure 1 For example, and without limitation, in some alternative embodiments, rotor blade 112 does not include hub pitch mechanism 126.

[0056] Rotor blade 112 includes an inner blade portion 128 and an outer blade portion 130. In the exemplary embodiment, inner blade portion 128 and outer blade portion 130 are formed independently of one another. When coupled together, inner blade portion 128 and outer blade portion 130 collectively define a length of rotor blade 112 from hub end 120 to distal end 122, generally indicated by L1. Specifically, in the exemplary embodiment, inner blade portion 128 includes an inner blade body 132 that extends longitudinally from hub end 120 (or, more generally, a first end of inner blade portion 128) to a connection end 134 (or, more generally, a second end of inner blade portion 128). Outer blade portion 130 includes an outer blade body 136 that extends longitudinally from a pivot end 138 (or, more generally, a first end of outer blade portion 130) to distal end 122 (or, more generally, a second end of outer blade portion 130). In an alternative embodiment, outer blade portion 130 extends at least partially at an angle relative to inner blade portion 128. For example, and without limitation, in at least some alternative embodiments, outer blade portion 130 is coupled to inner blade portion 128 in an inclined, sail-like configuration. In further alternative embodiments, outer blade portion 130 includes a folded tip (not shown) that extends obliquely relative to longitudinal axis 123. In still further alternative embodiments, outer blade portion 130 is oriented in any manner relative to inner blade portion 128 that enables rotor blade 112 to function as described herein.

[0057] In the exemplary embodiment, inner blade portion 128 and outer blade portion 130 are substantially hollow within inner blade body 132 and outer blade body 136, respectively. In alternative embodiments, inner blade body 132 and outer blade body 136 each include a plurality of blade support structures (not shown), such as, for example and without limitation, spar caps and spar web supports. In such embodiments, the blade support structures extend within and support inner blade body 132 and outer blade body 136, respectively. In further alternative embodiments, inner blade body 132 and outer blade body 136 include an internal filler material (e.g., polyurethane foam) located within at least one of inner blade body 132 and outer blade body 136. In still further alternative embodiments, at least one of inner blade portion 128 and outer blade portion 130 is non-hollow. In still further alternative embodiments, inner blade portion 128 and outer blade portion 130 include any internal structure that enables rotor blade 112 to function as described herein.

[0058] In the exemplary embodiment, inner blade portion 128 defines a length, generally indicated at L2, between hub end 120 and connection end 134. Outer blade portion 130 defines a length, generally indicated at L3, between pivot end 138 and distal end 122. In the exemplary embodiment, length L2 of inner blade portion 128 is greater than length L3 of outer blade portion 130. More specifically, in the exemplary embodiment, length L1 of rotor blade 112 is approximately 65 meters, length L2 of inner blade portion 128 is approximately 40 meters, and length L3 of outer blade portion 130 is approximately 25 meters. In alternative embodiments, inner blade portion 128 and outer blade portion 130 have any lengths L2, L3 that enable rotor blade 112 to function as described herein. In the exemplary embodiment, lengths L2, L3 of inner blade portion 128 and outer blade portion 130 collectively define length L1 of rotor blade 112. In an alternative embodiment, rotor blade 112 includes at least one or more additional blade portions (not shown) extending along length L1 of rotor blade 112 in addition to inner blade portion 128 and outer blade portion 130 .

[0059] In the exemplary embodiment, outer blade portion 130 is pivotally coupled to inner blade portion 128. In other words, in the exemplary embodiment, outer blade portion 130 is coupled to inner blade portion 128 such that outer blade portion 130 can rotate relative to inner blade portion 128. In particular, outer blade portion 130 is configured for bi-directional (e.g., clockwise and counterclockwise) rotation relative to inner blade portion 128. In an alternative embodiment, outer blade portion 130 is configured for multi-directional (e.g., pitch and yaw) pivoting relative to inner blade portion 128. In the exemplary embodiment, outer blade portion 130 is configured to pivot relative to inner blade portion 128. Figure 1 124 relative to inner blade portion 128 about longitudinal axis 124. In an alternative embodiment, outer blade portion 130 is configured to rotate between + / - 1 degree and + / - 3 degrees relative to inner blade portion 128 about longitudinal axis 124. In an alternative embodiment, outer blade portion 130 is configured to rotate at least + / - 5 degrees relative to inner blade portion 128 about longitudinal axis 124. In an alternative embodiment, outer blade portion 130 is configured to rotate any angle relative to inner blade portion 128 about longitudinal axis 124 that enables rotor blade 112 to function as described herein.

[0060] In the exemplary embodiment, pivotably coupling outer blade portion 130 to inner blade portion 128 facilitates rotation (i.e., pitching) of outer blade portion 130 about longitudinal axis 124 while inner blade portion 128 remains in position (i.e., does not rotate) relative to longitudinal axis 124. Pivotally coupling outer blade portion 130 to inner blade portion 128 also facilitates rotating outer blade portion 130 relative to inner blade portion 128 while inner and outer blade portions 128, 130, are each rotated about longitudinal axis 124 by hub pitch mechanism 126. In other words, in the exemplary embodiment, hub pitch mechanism 126 is configured to rotate the entire rotor blade 112 about longitudinal axis 124 (i.e., to rotate inner and outer blade portions 128, 130 in rotational synchronization with one another), and outer blade portion 130 is further controllable to rotate about longitudinal axis 124 relative to inner blade portion 128. In alternative embodiments where outer blade portion 130 extends at least partially obliquely relative to inner blade portion 128 , pivotably coupling outer blade portion 130 to inner blade portion 128 facilitates rotating outer blade portion 130 about a longitudinal axis (not shown) of outer blade portion 130 .

[0061] In the exemplary embodiment, rotor blade 112 includes a bearing 140, or more broadly, a rotatable element. As used herein throughout the specification and claims, the terms "rotatable element" and "bearing element" are to be understood as having substantially the same meaning. Bearing 140 includes a first end 142 coupled to inner blade portion 128 and a second end 144 coupled to outer blade portion 130. Bearing element 140 includes a bearing body 146 extending longitudinally between bearing first end 142 and bearing second end 144. Bearing second end 144 is rotatable relative to bearing first end 142 about longitudinal axis 124 to facilitate rotation, tilting, or other similar movement of outer blade portion 130 relative to inner blade portion 128. In particular, in the exemplary embodiment, bearing body 146 is configured to elastically deform about longitudinal axis 124 (i.e., twist about the length of bearing body 146 between bearing first end 142 and bearing second end 144) to facilitate rotation of bearing second end 144 relative to bearing first end 142. More specifically, in the exemplary embodiment, bearing element 140 is an elastically flexing bearing and is constructed from a resilient material capable of repeated rotational flexure without damaging or splintering bearing body 146. In the exemplary embodiment, bearing body 146 is formed from a composite material. In alternative embodiments, bearing body 146 is formed from any material that enables bearing element 140 to function as described herein. For example, and without limitation, in some alternative embodiments, bearing element 140 is formed from at least one of a metal, a non-metal, a polymer composite, and a metal composite.

[0062] In the exemplary embodiment, bearing element 140 is configured for low torsional resistance (i.e., low resistance to rotational deformation about longitudinal axis 124) and relatively high bending resistance (i.e., high resistance to tilting deformation relative to longitudinal axis 124). As a result, in the exemplary embodiment, bearing element 140 is preferably provided in wind turbine 100 (at Figure 1 1 and 2. The outer blade portion 130 is provided with structural support relative to various forces (e.g., wind loads and centrifugal loads) acting on the outer blade portion 130 during use. In addition, the bearing element 140 facilitates the outer blade portion 130 to be supported during use of the wind turbine 100 (shown in FIG. Figure 1 ) during use of the outer blade portion 130 relative to the inner blade portion 128.

[0063] In the exemplary embodiment, outer blade portion 130 is coupled to inner blade portion 128 via bearing element 140 such that gap 141 (at Figure 3 130 ). A gap 141 (shown in FIG. 1 ) is defined between a connection end 134 of inner blade portion 128 and a pivot end 138 of outer blade portion 130. Gap 141 allows for reduced static and dynamic friction between inner blade portion 128 and outer blade portion 130 to facilitate pitching outer blade portion 130. In an alternative embodiment, gap 141 is sealed by a flexible membrane (not shown). In further alternative embodiments, inner blade portion 128 is coupled to outer blade portion 130 in any manner that enables rotor blade 112 to function as described herein.

[0064] In the exemplary embodiment, inner blade portion 128 includes a support structure 148 that extends within inner blade body 132. Support structure 148 is coupled to inner blade body 132 at at least two points of contact with inner blade body 132. Support structure 148 is coupled to inner blade body 132 at a longitudinal point between hub pitch mechanism 126 and connection end 134. Thus, in the exemplary embodiment, the pivotable coupling between inner blade portion 128 and outer blade portion 130 via bearing element 140 does not interfere with hub pitch mechanism 126. In alternative embodiments, support structure 148 is coupled to inner blade body 132 in any manner that enables rotor blade 112 to function as described herein. In the exemplary embodiment, support structure 148 is shaped to complement inner blade body 132. More specifically, in the exemplary embodiment, support structure 148 defines an outer perimeter corresponding to an inner surface 150 of inner blade body 132 at the point of inner blade body 132 where support structure 148 is coupled. In other words, in the exemplary embodiment, support structure 148 is sized to contact inner blade body 132 along the entire perimeter of support structure 148. In alternative embodiments, support structure 148 is embedded in inner blade body 132. In further alternative embodiments, support structure 148 is shaped and sized in any manner that enables rotor blade 112 to function as described herein. In the exemplary embodiment, support structure 148 is formed from a polymer-based composite material. In alternative embodiments, support structure 148 is formed from any material that enables support structure 148 to function as described herein. For example, and without limitation, in some alternative embodiments, support structure 148 is formed from at least one of a polymer, a metal and / or a metal alloy, and a metal composite material.

[0065] In the exemplary embodiment, bearing first end 142 is coupled to support structure 148. Specifically, bearing element 140 is fixedly coupled to support structure 148 such that bearing first end 142 cannot rotate relative to support structure 148. Bearing body 146 extends along longitudinal axis 124 away from support structure 148 toward outer blade portion 130. Bearing body 146 defines a width (generally indicated by W1) and a height (e.g., extending into and out of the page). In alternative embodiments, bearing body 146 comprises a tubular or polygonal cross-section. In the exemplary embodiment, the height of bearing body 146 (not shown) is greater than width W1 of bearing body 146, such that bearing body 146 has a generally rectangular cross-section. Bearing body 146 defines a length, generally indicated by L4, extending between bearing first end 142 and bearing second end 144. In the exemplary embodiment, bearing element 140 is positioned within inner blade portion 128 and outer blade portion 130 such that bearing body length L4 is substantially parallel to longitudinal axis 124 of rotor blade 112. In alternative embodiments, bearing body 146 has any shape that enables rotor blade 112 to function as described herein. For example, and without limitation, in some alternative embodiments, bearing body 146 is curved along length L4 of bearing body 146 .

[0066] In the exemplary embodiment, rotor blade 112 includes a pitch device 152 coupled to outer blade portion 130 and an inner hub 154 coupled to inner blade portion 128. A bearing body 146 extends through inner hub 154 and is integrally formed with pitch device 152 at bearing second end 144. In an alternative embodiment, bearing element 140 is removably attached to pitch device 152. An actuation mechanism (not shown) is configured to impart relative motion to outer blade portion 130 relative to inner blade portion 128. More specifically, the actuation mechanism is configured to drive rotation of pitch device 152 relative to inner hub 154, thereby driving rotation of bearing second end 144 relative to bearing first end 142. In the exemplary embodiment, the actuation mechanism includes a gear and pinion (not shown) anchored to the inner hub for driving rotation of pitch device 152 relative to inner hub 154. In alternative embodiments, the actuation mechanism may be any one of a motor drive, a hydraulic actuator, and a pneumatic actuator. In still other alternative embodiments, rotor blade 112 includes any actuation mechanism that enables rotor blade 112 to function as described herein. For example, as described below with respect to Figure 5 and Figure 6 As described in greater detail, in some alternative embodiments, the actuation mechanism may include a motorized cable system.

[0067] In the exemplary embodiment, at wind turbine 100 (at Figure 1During operation of the hub pitch mechanism 126 (not shown), the hub pitch mechanism 126 may be controlled to pitch the entire rotor blade 112 (e.g., to pitch the inner blade portion 128 and the outer blade portion 130 relative to the rotatable hub 110). Additionally, the actuation mechanism (not shown) may be controlled to pitch only the outer blade portion 130 of the rotor blade 112.

[0068] Figure 3 is used in a wind turbine 100 (in Figure 1 ) is an enlarged schematic cross-sectional view of an alternative rotor blade 112 for use in FIG. Figure 4 yes Figure 3 A schematic end view of a portion of an alternative rotor blade 112 is shown. Figure 3 and Figure 4 The alternative rotor blade 112 shown in FIG is substantially similar to the one described above with respect to FIG. Figure 2 The rotor blades 112 are as follows.

[0069] In the exemplary embodiment, rotor blade 112 includes a pivot structure 156 coupled to outer blade portion 130. Pivot structure 156 is shaped to correspond to outer blade body 136. More specifically, in the exemplary embodiment, pivot structure 156 defines an outer perimeter corresponding to an inner surface 158 of outer blade body 136 at the point of outer blade body 136 where pivot structure 156 is coupled (e.g., pivot end 138). In other words, in the exemplary embodiment, support structure 148 is sized to contact inner blade body 132 along the entire perimeter of support structure 148. In alternative embodiments, pivot structure 156 is coupled to outer blade body 136 at at least two points of contact with outer blade body 136. In still other embodiments, pivot structure 156 is coupled to outer blade body 136 in any manner that enables rotor blade 112 to function as described herein.

[0070] In the exemplary embodiment, the bearing element 140 includes four bearing rods 160 (each at Figure 4 ), the bearing rods are each at a corresponding first end 142 (at Figure 3130 ). More specifically, in the exemplary embodiment, bearing rods 160 are each coupled to support structure 148 near the periphery of support structure 148 (i.e., near inner blade body 132). In alternative embodiments, bearing element 140 includes any number of bearing rods 160 that enables rotor blade 112 to function as described herein. For example, and without limitation, in alternative embodiments, the number and placement of bearing rods 160 are based on a desired torsional stiffness and / or bending stiffness of bearing element 140. In particular, increasing the number of bearing rods 160 increases the torsional stiffness of the bearing element (i.e., increases the drive power required to impart rotational motion between outer blade portion 130 and inner blade portion 128) while also increasing the bending stiffness of rotor blade 112 (i.e., provides increased resistance to bending between inner blade portion 128 and outer blade portion 130). In the exemplary embodiment, bearing rods 160 are each coupled to pivot structure 156 at respective second ends 144 and each extend obliquely relative to longitudinal axis 124 between first end 142 and second end 144. In other words, in the exemplary embodiment, bearing rods 160 generally converge at pivot structure 156. In alternative embodiments, bearing rods 160 are coupled to inner blade portion 128 and outer blade portion 130 in any manner that enables rotor blade 112 to function as described herein.

[0071] refer to Figure 4 , in the exemplary embodiment, inner blade portion 128 and pivot structure 156 of an alternative rotor blade 112 are shown. In the exemplary embodiment, pivot structure 156 is annular, defining an interior opening, generally indicated at 162, through which support structure 148 is visible. More specifically, pivot structure 156 is shaped as an annular, elliptical, or circular shape corresponding to the cross-section of outer blade portion 130. Bearing rods 160 are each coupled to pivot structure 156 at second end 144 such that second ends 144 are substantially circumferentially spaced about pivot structure 156. In an alternative embodiment, bearing rods 160 extend between support structure 148 and pivot structure 156 in any manner that enables rotor blade 112 to function as described herein.

[0072] Return Reference Figure 3 In the exemplary embodiment, pitch device 152 and inner hub 154 are shown in phantom to illustrate the internal connection between bearing rod 160 and pivot structure 156. More specifically, in the exemplary embodiment, pitch device 152 is coupled to pivot structure 156. Pitch drive 152 is configured to operate in a manner similar to that described above with respect to Figure 2Rotation of outer blade portion 130 relative to inner blade portion 128 is driven in substantially the same manner as described herein. Specifically, an actuation mechanism (not shown) is coupled to a pitch device and is configured to drive rotation of pitch device 152 relative to inner hub 154 to drive rotation of bearing second end 144 relative to bearing first end 142. In alternative embodiments, pitch device 152 and inner hub 154 are configured in any manner that enables rotor blade 112 to function as described herein. In further alternative embodiments, rotor blade 112 does not include at least one of pitch device 152 and inner hub 154.

[0073] Figure 5 is used in a wind turbine 100 (in Figure 1 ), a schematic cross-sectional view of an additional alternative rotor blade 112 for use in FIG. Figure 5 The alternative rotor blade 112 shown in FIG is substantially similar to the one described above with respect to FIG. Figure 2 The rotor blades 112 are as follows.

[0074] In the exemplary embodiment, rotor blade 112 includes a plurality of cables 164. More specifically, in the exemplary embodiment, rotor blade 112 includes three cables 164 that are coupled at hub end 120 of inner blade portion 128 and extend through inner blade body 132 to outer blade portion 130. In alternative embodiments, rotor blade 112 includes any number of cables that enables the rotor blade to function as described herein.

[0075] In the exemplary embodiment, bearing element 140 extends between inner hub 154 and pitch device 152. More specifically, in the exemplary embodiment, bearing first end 142 is coupled to inner hub 154, and bearing second end 144 is coupled to pitch device 152. In the exemplary embodiment, bearing element 140 is a pitch bearing that is configured to facilitate rotation of bearing second end 144 relative to bearing first end 142. Pitch device 152 is coupled to outer blade portion 130. As a result, rotation of bearing second end 144 relative to bearing first end 142 facilitates rotation of outer blade portion 130 relative to inner blade portion 128 about longitudinal axis 124.

[0076] In the exemplary embodiment, cable 164 is coupled to hub end 120 of inner blade portion 128 and extends therefrom to pitch device 152. In the exemplary embodiment, an actuation mechanism (not shown) is positioned coupled to inner hub 154. In alternative embodiments, the actuation mechanism (not shown) is located in any component of wind turbine 100 that enables the actuation mechanism (not shown) to function as described herein. For example, and without limitation, in some alternative embodiments, the actuation mechanism is positioned near pitch device 152.

[0077] In the exemplary embodiment, cables 164 are coupled to pitch device 152 such that the cables are spaced substantially equally around the circumference of pitch device 152 to facilitate imparting rotational motion. More specifically, in the exemplary embodiment, bearing element 140 is preloaded by cables 164. In other words, cables 164 apply an axial load to bearing element 140 to stabilize the positioning of outer blade portion 130 relative to inner blade portion 128 and drive pitching of outer blade portion 130. Cables 164 are maintained with substantially equal tension to maintain rotational alignment of outer blade portion 130 relative to inner blade portion 128. An actuation mechanism (not shown) is configured to impart rotational motion to pitch device 152 relative to inner hub 154, thereby imparting rotation to bearing second end 144 relative to bearing first end 142 to facilitate rotating outer blade portion 130 relative to inner blade portion 128. In alternative embodiments, cables 164 are coupled to pitch device 152 in any manner that enables rotor blade 112 to function as described herein.

[0078] Figure 6 is used in a wind turbine 100 (in Figure 1 ) is a schematic cross-sectional view of yet another alternative rotor blade 112 for use in FIG. Figure 6 The alternative rotor blade 112 shown in FIG is substantially similar to the one described above with respect to FIG. Figure 5 The rotor blades 112 are as follows.

[0079] In the exemplary embodiment, bearing element 140 is a roller bearing. In particular, in the exemplary embodiment, bearing element 140 is a tapered roller bearing. Bearing element 140 is configured to Figure 1 14. Bearing element 140 is subjected to large axial compressive loads (i.e., compressive loads along longitudinal axis 124 of rotor blade 112) during operation (shown in FIG. 14). Specifically, bearing element 140 includes an inner cup 166, an outer cup 168, and a plurality of tapered roller elements 170 coupled between inner cup 166 and outer cup 168. In the exemplary embodiment, inner cup 166 defines bearing first end 142, and outer cup 168 defines bearing second end 144.

[0080] In the exemplary embodiment, an inner cup 166 is coupled to the inner blade portion 128, and an outer cup 168 is coupled to the outer blade portion 130. Specifically, in the exemplary embodiment, a support structure 148 is coupled to the inner blade body 132 at a connection end 134 of the inner blade portion 128. The outer blade portion 130 includes a pivot structure 156 coupled to the outer blade body 136 at a pivot end 138 of the outer blade portion 130. The inner cup 166 is fixedly coupled to the support structure 148, and the outer cup 168 is fixedly coupled to the pivot structure 156. A roller element 170 is configured to rotate between the inner cup 166 and the outer cup 168.

[0081] In the exemplary embodiment, inner cup 166 and outer cup 168 define a bearing bore, generally indicated at 172. Roller elements 170 each include a bore end 174 and an outer end 176. For each of roller elements 170, bore end 174 is located adjacent bearing bore 172, and roller elements 170 extend radially outward therefrom to outer end 176. In the exemplary embodiment, roller elements 170 taper between bore end 174 and outer end 176. In an alternative embodiment, bearing element 140 is an angular contact bearing. In yet other alternative embodiments, bearing element 140 is any rotatable element that enables rotor blade 112 to function as described herein.

[0082] In the exemplary embodiment, rotor blade 112 includes a hub end 120 (at Figure 5 164 extends to the outer cup 168. In alternative embodiments, the rotor blade 112 includes any number of cables 164 that enables the rotor blade 112 to function as described herein. The cables 164 are operable to communicate with the outer cup 168 as described above. Figure 5 Rotation of outer blade portion 130 relative to inner blade portion 128 is driven in substantially the same manner as described above. Specifically, in the exemplary embodiment, cables 164 are coupled to outer cup 168 with substantially uniform tension. Uniform tension can be achieved, in particular, by incorporating springs (not shown) at one or both ends of cables 164. An actuation mechanism (not shown) can also be used to adjust the tension of cables 164 relative to one another. In alternative embodiments, actuation mechanism (not shown) is configured to drive rotation of outer blade portion 130 relative to inner blade portion 128 in any manner that enables rotor blade 112 to function as described herein.

[0083] Figure 7 is assembled for use in a wind turbine 100 (in Figure 1 Flowchart of an exemplary method 200 for rotating a rotor blade 112 used in a rotor blade 112 shown in FIG. The blade 112 includes a first end 120 and a second end 134 (each at Figure 2The blade 112 also includes an inner blade portion 128 having a first end 138 and a second end 122 (each at Figure 2 1 . The method 200 includes coupling 202 the first end 138 of the outer blade portion 130 to the second end 134 of the inner blade portion 128. The method 200 also includes coupling 204 the first end 142 of the rotatable element 140 to the inner blade portion 128. The method 200 includes coupling 208 the second end 144 of the rotatable element 140 to the outer blade portion 130 such that the outer blade portion 130 is rotatable relative to the inner blade portion 128.

[0084] Exemplary technical effects of the methods, systems, and apparatus described herein include at least one of: (a) increasing the useful life of wind turbine components; (b) reducing maintenance and repair of wind turbine components; (c) increasing the modularity of rotor blades; and (d) improving control of the pitch of rotor blades.

[0085] Exemplary embodiments of wind turbines, rotor blades for use in wind turbine systems, and methods for assembling rotors for use in wind turbine systems are described above in detail. The methods and systems are not limited to the specific embodiments described herein; rather, components of the systems and / or steps of the methods may be used separately or independently of other components and / or steps described herein. For example, the methods may also be used in conjunction with other turbine components and are not limited to practice with only the wind turbine systems described herein. Rather, the exemplary embodiments may be implemented and used in conjunction with many other wind turbine applications.

[0086] Although specific features of various embodiments of the present disclosure may be shown in some drawings but not in others, this is for convenience only. According to the principles of the present disclosure, any feature of an accompanying drawing may be referenced and / or claimed in combination with any feature of any other accompanying drawing.

[0087] This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. A wind turbine comprising: a hub capable of rotating about an axis; a blade coupled to the hub and comprising: an inner blade portion including a first end and a second end, the inner blade portion being coupled to the hub at the first end and extending radially outward from the hub to the second end; and an outer blade portion comprising a first end and a second end, the first end of the outer blade portion being pivotally coupled to the second end of the inner blade portion; and a rotatable element extending between the inner blade portion and the outer blade portion, the rotatable element including a first end coupled to the inner blade portion and a second end coupled to the outer blade portion, wherein the second end of the rotatable element is rotatable relative to the first end of the rotatable element to facilitate rotating the outer blade portion relative to the inner blade portion, wherein the rotatable element is an elastic flexure bearing.

2. The wind turbine according to claim 1, wherein: The blade defines a longitudinal axis extending from the first end of the inner blade portion to the second end of the outer blade portion, wherein the outer blade portion is configured to rotate about the longitudinal axis relative to the inner blade portion.

3. The wind turbine according to claim 1, wherein: The blade defines a longitudinal axis extending from the first end of the inner blade portion to the second end of the outer blade portion, wherein the first end of the inner blade portion is pivotally coupled to the hub such that the inner blade portion is configured to rotate about the longitudinal axis.

4. The wind turbine according to claim 1, wherein: The outer blade portion extends obliquely relative to the inner blade portion.

5. The wind turbine according to claim 1, wherein: The second end of the rotatable element is rotatable at least + / - 1 degree relative to the first end of the rotatable element.

6. The wind turbine according to claim 1, wherein: Also comprising a support structure positioned within the inner blade portion, the rotatable element further comprising a body extending from the support structure to a length of the outer blade portion, wherein the body is configured for elastic deformation about the length of the body.

7. The wind turbine according to claim 6, wherein: The body includes a plurality of rods that each extend from the support structure to the outer blade portion.

8. The wind turbine according to claim 1, wherein: Also included are a plurality of cables extending between the inner blade portion and the outer blade portion, the plurality of cables being configured to stabilize a position of the outer blade portion relative to the inner blade portion and to drive pitching of the outer blade portion.

9. A blade for use in a wind turbine system, comprising: an inner blade portion comprising a first end and a second end; an outer blade portion comprising a first end and a second end, the first end of the outer blade portion being coupled to the second end of the inner blade portion; and a rotatable element extending between the inner blade portion and the outer blade portion, the rotatable element including a first end coupled to the inner blade portion and a second end coupled to the outer blade portion, wherein the second end of the rotatable element is rotatable relative to the first end of the rotatable element to facilitate rotating the outer blade portion relative to the inner blade portion, wherein the rotatable element is an elastic flexure bearing.

10. The blade according to claim 9, characterized in that The second end of the rotatable element is rotatable at least + / - 1 degree relative to the first end of the rotatable element.

11. The blade according to claim 9, characterized in that Also included is a support structure positioned within the inner blade portion, the rotatable element further comprising a flexible support member extending from the support structure to the outer blade portion.

12. A method of assembling a blade for use in a wind turbine system, the blade comprising an inner blade portion having a first end and a second end and an outer blade portion having a first end and a second end, the method comprising: coupling the first end of the outer blade portion to the second end of the inner blade portion; coupling a first end of a rotatable element to the inner blade portion; and coupling the second end of the rotatable element to the outer blade portion such that the outer blade portion is rotatable relative to the inner blade portion, Wherein, the rotatable element is an elastic flexure bearing.

13. The method according to claim 12, characterized in that The second end of the rotatable element is rotatable at least + / - 1 degree relative to the first end of the rotatable element.

14. The method according to claim 12, characterized in that Also included is positioning a support structure within the inner blade portion, wherein coupling the first end of the rotatable element further includes coupling a flexible support member of the rotatable element to the support structure, and wherein coupling the second end of the rotatable element further includes coupling the flexible support member to the outer blade portion.

15. The method according to claim 12, characterized in that Also included is coupling an actuation mechanism to at least one of the inner blade portion and the outer blade portion, the actuation mechanism configured to drive rotation of the outer blade portion relative to the inner blade portion.

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