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

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

As wind turbines continue to increase in size, the rotor blades also increase in size. Thus, larger rotor blades may be constructed in segments that can be assembled on site via one or more pin joints. For example, certain jointed rotor blades may include a first blade segment having a beam structure that is received within a receiving section of a second blade segment that is further secured together via one or more span-wise and/or chord-wise extending pins that transfer the blade bending moment from one segment to the other. Thus, the pin joints are configured to allow the blade tip to flex to withstand some of this load.

The bending moment, however, results in pin deflection at the ends thereof and an opposite deflection at the center. This deflection causes problems in the pin joint supports due to the rotational deflection that induces bending stresses in the supports and peaking of crush stresses in the supports and any bushings that may be used. Examples of prior art solutions are available in documents <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

Thus, the present disclosure is directed to an improved wind turbine jointed rotor blade having at least one chord-wise extending pin supported via one or more structural members that addresses the aforementioned issues.

In one aspect, the present disclosure is directed to a rotor blade for a wind turbine. The rotor blade includes a first blade segment and a second blade segment extending in opposite directions from a chord-wise joint. Each of the first and second blade segments includes at least one shell member defining an airfoil surface and an internal support structure. The internal support structure of the first blade segment includes a beam structure extending lengthwise, whereas the internal support structure of the second blade segment includes a receiving section that receives the beam structure of the first blade segment. Further, the rotor blade includes at least one chord-wise extending pin positioned through the beam structure and the receiving section at the chord-wise joint so as to secure the first and second blade segments together. Moreover, the rotor blade includes at least one additional support member that receives at least a portion of the chord-wise extending pin so as to reduce a chord-wise bending deflection of the chord-wise extending pin at the chord-wise joint.

In one embodiment, at least one beam structure of the first blade segment is hollow and the additional support member includes at least one web member. In such embodiment, the chord-wise extending pin extends through the web member and the web member is arranged within the hollow beam structure. In further embodiments, the web member(s) may be integral with the beam structure.

In several embodiments, the chord-wise extending pin(s) may include a first chord-wise extending pin and a second chord-wise extending pin. In such embodiments, the first chord-wise extending pin and the second chord-wise extending pin may be arranged in an end-to-end configuration. In further embodiments, ends of the first chord-wise extending pin and the second chord-wise extending pin may abut against each other within the web member(s).

In particular embodiments, the web member(s) may include a first web member and a second web member. In such embodiments, ends of the first chord-wise extending pin and the second chord-wise extending pin may abut against each other between the first and second web members.

In additional embodiments, the first chord-wise extending pin and the second chord-wise extending pin may be spaced apart. In such embodiments, the first chord-wise extending pin may extend through a first side of the beam structure and the second chord-wise extending pin may extend through an opposing, second side of the beam structure, with the first and second web members arranged outside of the hollow beam structure.

In further embodiments, the additional support member may be at least one tube positioned within the hollow beam structure. In such embodiments, the chord-wise extending pin may extend through the tube(s). In alternative embodiments, the additional support member(s) may be at least one filler material that fills the hollow beam structure. In such embodiments, the chord-wise extending pin may extend through the filler material(s).

In another aspect, the present disclosure is directed to a method of securing blade segments of a rotor blade of a wind turbine together. The method includes providing a first blade segment having a beam structure that extends lengthwise in a generally span-wise direction. The method also includes providing a second blade segment having a receiving section that extends lengthwise in the generally span-wise direction. Further, the method includes inserting the beam structure of the first blade segment into the receiving section of the second blade segment such that the first and second blade segments extend in opposite directions from a chord-wise joint. As such, the method includes inserting at least one chord-wise extending pin through the beam structure and the receiving section at the chord-wise joint so as to join the first and second blade segments together and through at least one additional support member so as to reduce a chord-wise bending deflection of the chord-wise extending pin at the chord-wise joint.

In one embodiment, the method may include forming the beam structure of the first blade segment such that the additional support member(s) is integral therewith. In another embodiment, the additional support member(s) may include one or more web members, one or more tubes, and/or a filler material.

In further embodiments, the method may include arranging the additional support member(s) within the beam structure. Alternatively, the method may include arranging the additional support member(s) outside of the beam structure. It should be further understood that the method may include any of the additional features and/or steps described herein.

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

Referring now to the drawings, <FIG> illustrates a perspective view of one embodiment of a wind turbine <NUM> according to the present invention. In the illustrated embodiment, the wind turbine <NUM> is a horizontal-axis wind turbine. In addition, as shown, the wind turbine <NUM> may include a tower <NUM> that extends from a support surface <NUM>, a nacelle <NUM> mounted on the tower <NUM>, a generator <NUM> positioned within the nacelle <NUM>, a gearbox <NUM> coupled to the generator <NUM>, and a rotor <NUM> that is rotationally coupled to the gearbox <NUM> with a rotor shaft <NUM>. Further, as shown, the rotor <NUM> includes a rotatable hub <NUM> and at least one rotor blade <NUM> coupled to and extending outward from the rotatable hub <NUM>. As shown, the rotor blade <NUM> includes a blade tip <NUM> and a blade root <NUM>.

Referring now to <FIG>, a plan view of one of the rotor blades <NUM> of <FIG> is illustrated. As shown, the rotor blade <NUM> may include a first blade segment <NUM> and a second blade segment <NUM>. Further, as shown, the first blade segment <NUM> and the second blade segment <NUM> may each extend in opposite directions from a chord-wise joint <NUM>. In addition, as shown, each of the blade segments <NUM>, <NUM> may include a pressure side shell member and a suction side shell member. The first blade segment <NUM> and the second blade segment <NUM> are connected by at least an internal support structure <NUM> extending into both blade segments <NUM>, <NUM> to facilitate joining of the blade segments <NUM>, <NUM>. The arrow <NUM> shows that the segmented rotor blade <NUM> in the illustrated example includes two blade segments <NUM>, <NUM> and that these blade segments <NUM>, <NUM> are joined by inserting the internal support structure <NUM> into the second blade segment <NUM>. In addition, as shown, the second blade segment includes multiple spar structures <NUM> (also referred to herein as spar caps) that extend lengthwise for connecting with a blade root section <NUM> of the rotor blade <NUM> (which is shown in more detail in <FIG>) and with the beam structure <NUM> of the first blade segment <NUM> (which is shown in more detail in <FIG>).

Referring now to <FIG>, a perspective view of a section of the first blade segment <NUM> according to the present disclosure is illustrated. As shown, the first blade segment <NUM> includes a beam structure <NUM> that forms a portion of the internal support structure <NUM> and extends lengthwise for structurally connecting with the second blade segment <NUM>. Further, as shown, the beam structure <NUM> forms a part of the first blade segment <NUM> having an extension protruding from a spar section <NUM>, thereby forming an extending spar section. The beam structure <NUM> includes a shear web <NUM> connected with a suction side spar cap <NUM> and a pressure side spar cap <NUM>.

Moreover, as shown, the first blade segment <NUM> may include one or more first pin joints at a first end <NUM> of the beam structure <NUM>. In one embodiment, the pin joint may include a pin that is in a tight interference fit with a bushing. More specifically, as shown, the pin joint(s) may include one pin tube <NUM> located on the beam structure <NUM>. Thus, as shown, the pin tube <NUM> may be oriented in a span-wise direction. Further, the first blade segment <NUM> may also include a pin joint slot <NUM> located on the beam structure <NUM> at the chord-wise joint <NUM>. Moreover, as shown, the pin joint slot <NUM> may be oriented in a chord-wise direction.

Referring now to <FIG>, a perspective view of a section of the second blade segment <NUM> at the chord-wise joint <NUM> according to the present disclosure is illustrated. As shown, the second blade segment <NUM> includes a receiving section <NUM> extending lengthwise within the second blade segment <NUM> for receiving the beam structure <NUM> of the first blade segment <NUM>. Further, as shown, the receiving section <NUM> may include the spar structures <NUM> that extend lengthwise for connecting with the beam structure <NUM> of the first blade segment <NUM>.

Referring now to <FIG>, an assembly <NUM> of the rotor blade <NUM> having the first blade segment <NUM> joined with the second blade segment <NUM> according to the present disclosure is illustrated. As shown, the assembly <NUM> illustrates multiple supporting structures beneath outer shell members of the rotor blade <NUM> having the first blade segment <NUM> joined with the second blade segment <NUM>. Further, as shown, the receiving section <NUM> includes the multiple spar structures <NUM> extending lengthwise and supports the beam structure <NUM>. The receiving section <NUM> also includes a rectangular fastening element <NUM> that connects with the pin tube <NUM> of the beam structure <NUM> in the span-wise direction. Further, the first and the second blade segments <NUM>, <NUM> may also include chord-wise members <NUM>, <NUM> respectively at the chord-wise joint <NUM>. In another embodiment, each of the spar structures <NUM>, the rectangular fastening element <NUM>, and the chord-wise members <NUM>, <NUM> may be constructed of glass reinforced fibers.

Referring now to <FIG>, an exploded perspective view of the multiple supporting structures of the assembly <NUM> towards the receiving section <NUM> of the rotor blade <NUM> is illustrated. As shown, the pair of spar structures <NUM> is configured to receive the beam structure <NUM> and may include pin joint slots <NUM>, <NUM> that are aligned with the pin joint slot <NUM> of the beam structure <NUM> through which a chord-wise extending <NUM> may be inserted. Further, as shown, the chord-wise extending <NUM> may be configured to remain in a tight interference fit within the aligning pin joint slots <NUM>, <NUM>, <NUM> such that spar structures <NUM> and the beam structure <NUM> are joined together during assembly. Further, <FIG> also illustrates the rectangular fastening element <NUM> that includes a pin joint slot <NUM> configured for receiving the pin tube <NUM> of the beam structure <NUM>. As such, the pin tube <NUM> is configured to form a tight interference fit pined joint. Further, the pair of spar structures <NUM> may be joined together at one end <NUM> using any suitable adhesive material or an elastomeric seal.

Referring to <FIG>, various cross-sectional views of the chord-wise joint <NUM> according to the present disclosure are illustrated. More particularly, <FIG> illustrates a cross-sectional view of the chord-wise joint <NUM> of <FIG> along section line <NUM>-<NUM> is illustrated. Thus, as shown, the chord-wise extending pin <NUM> is positioned through the chord-wise joint <NUM> so as to secure the internal support structures (i.e. the beam structure <NUM> and the receiving section <NUM>) of the first and second blade segments <NUM>, <NUM> together. Further, as shown generally in <FIG>, the rotor blade <NUM> includes at least one additional support member <NUM> that receives at least a portion of the chord-wise extending pin <NUM> so as to reduce a chord-wise bending deflection of the chord-wise extending pin at the chord-wise joint <NUM>.

More particularly, as shown, the beam structure <NUM> of the first blade segment <NUM> may be hollow. Thus, as shown in <FIG>, the additional support member(s) <NUM> may be a web member <NUM>. In such embodiments, the chord-wise extending pin(s) may extend through the web member(s). In addition, as shown in <FIG>, the web member(s) <NUM> may be arranged within the hollow beam structure <NUM>. In such embodiments, as shown, the web member(s) <NUM> may be integral with the beam structure <NUM>. Alternatively, as shown in <FIG>, the web member(s) <NUM> may be arranged outside of the beam structure <NUM>. Thus, in such embodiments, the web member(s) <NUM> may be separate from the beam structure <NUM>.

In several embodiments, as shown particularly in <FIG>, the chord-wise extending pin(s) <NUM> may include a first chord-wise extending pin <NUM> and a second chord-wise extending pin <NUM>. In such embodiments, as shown, the first chord-wise extending pin <NUM> and the second chord-wise extending pin <NUM> may be arranged in an end-to-end configuration. In further embodiments, as shown in <FIG>, ends <NUM>, <NUM> of the first chord-wise extending pin <NUM> and the second chord-wise extending pin <NUM> may abut against each other within the web member(s) <NUM>.

In alternative embodiments, as shown in <FIG>, the web member(s) <NUM> may include a first web member <NUM> and a second web member <NUM>. In such embodiments, as shown in <FIG>, the ends <NUM>, <NUM> of the first chord-wise extending pin <NUM> and the second chord-wise extending pin <NUM> may abut against each other between the first and second web members <NUM>, <NUM>.

Referring now to <FIG>, the first chord-wise extending pin <NUM> and the second chord-wise extending pin <NUM> may be spaced apart from each other. In such embodiments, as shown, the first chord-wise extending pin <NUM> may extend through a first side <NUM> of the beam structure <NUM>, whereas the second chord-wise extending pin <NUM> may extend through an opposing, second side <NUM> of the beam structure <NUM>. In addition, as shown, the web members <NUM> may be arranged outside of the beam structure <NUM>.

Referring now to <FIG>, in further embodiments, the additional support member <NUM> may also be at least one tube <NUM> positioned within the hollow beam structure <NUM>. In such embodiments, as shown, the chord-wise extending pin <NUM> may extend through the tube(s) <NUM>. In alternative embodiments, as shown in <FIG>, the additional support member(s) <NUM> may be at least one filler material <NUM> that fills the hollow beam structure <NUM>. In addition, as shown, the chord-wise extending pin <NUM> may extend through the filler material(s) <NUM>. In such embodiments, the filler material(s) <NUM> may correspond to foam, wood (e.g. balsa wood), or similar.

Referring now to <FIG>, a flow chart <NUM> of one embodiment of a method of securing blade segments of a rotor blade of a wind turbine together according to the present disclosure is illustrated. In general, the method <NUM> will be described herein with reference to the wind turbine <NUM> and the rotor blade <NUM> shown in <FIG>. However, it should be appreciated that the disclosed method <NUM> may be implemented with rotor blades having any other suitable configurations. In addition, although <FIG> depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure.

As shown at (<NUM>), the method <NUM> may include providing the first blade segment <NUM> having the beam structure <NUM> that extends lengthwise in a generally span-wise direction. As shown at (<NUM>), the method <NUM> may include providing the second blade segment <NUM> having the receiving section <NUM> that extends lengthwise in the generally span-wise direction. As shown at (<NUM>), the method <NUM> may include inserting the beam structure <NUM> of the first blade segment <NUM> into the receiving section <NUM> of the second blade segment <NUM> such that the first and second blade segments <NUM>, <NUM> extend in opposite directions from the chord-wise joint <NUM>. As shown at (<NUM>), the method <NUM> may include inserting at least one chord-wise extending pin <NUM> through the beam structure <NUM> and the receiving section <NUM> at the chord-wise joint <NUM> so as to join the first and second blade segments <NUM>, <NUM> together and through at least one additional support member <NUM> so as to reduce a chord-wise bending deflection of the chord-wise extending pin at the chord-wise joint <NUM>.

In one embodiment, the method <NUM> may include forming the beam structure <NUM> of the first blade segment <NUM> such that the additional support member(s) <NUM> is integral therewith. In another embodiment, as mentioned, the additional support member(s) <NUM> may include one or more web members <NUM>, one or more tubes <NUM>, and/or a filler material <NUM>.

In further embodiments, the method <NUM> may include arranging the additional support member(s) <NUM> within the beam structure <NUM>. Alternatively, the method <NUM> may include arranging the additional support member(s) <NUM> outside of the beam structure <NUM>.

While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the invention which is defined by the appended claims.

Claim 1:
A rotor blade (<NUM>) for a wind turbine (<NUM>), comprising:
a first blade segment (<NUM>) and a second blade segment (<NUM>) extending in opposite directions from a chord-wise joint, each of the first and second blade segments comprising at least one shell member defining an airfoil surface and an internal support structure (<NUM>),
the internal support structure of the first blade segment comprising a beam structure (<NUM>) extending lengthwise, the internal support structure of the second blade segment comprising a receiving section (<NUM>),
the receiving section receiving the beam structure of the first blade segment, wherein the at least one beam structure is hollow;
at least one chord-wise extending pin positioned through the beam structure and the receiving section at the chord-wise joint so as to secure the first and second blade segments together; and,
at least one additional support member receiving at least a portion of the chord-wise extending pin so as to reduce a chord-wise bending deflection of the chord-wise extending pin at the chord-wise joint, characterized in that the at least one additional support member comprises at least one web member (<NUM>),
the at least one chord-wise extending pin extends through the at least one web member, and the at least one web member is arranged within the hollow beam structure.