Patent Description:
Wind power generation refers to a method for generating electric power by using a windmill to convert wind energy into mechanical energy (i.e., rotational force) and then driving a generator to obtain electrical energy.

Wind power generation is being actively invested in the United States and Asia as well as in Europe, because wind power is the most economical renewable energy source developed so far and it is an indefinite, cost-free, and clean energy source that can be generated using wind.

The wind turbine for wind power generation may be classified into a vertical-axis wind turbine and a horizontal-axis wind turbine according to the direction of the rotary shaft. For example, the horizontal-axis wind turbine has been mainly applied to commercial wind farms because the horizontal-axis wind turbine is more efficient and more stable than the vertical-axis wind turbine.

The wind turbine includes a plurality of blades, and each blade is provided with spar caps to improve its strength. The spar caps are respectively disposed at an upper portion (i.e., suction side) and a lower portion (i.e., pressure side) of the blade and are connected through a shear web.

A plurality of spar caps may be installed in one blade. For example, four spar caps are installed between the core panels of the blade. Each spar cap must be bent and twisted according to the shape of the blade. However, the shape of the blade may be limited because it is difficult to bend or twist the spar cap depending on the constituent object. It is also necessary to prevent the formation of pores in the spar cap. If pores are formed in the spar cap, the strength of the spar cap may be decreased.

<CIT> discloses a method of manufacturing rotor blades for a wind turbine. The method includes forming a first spar cap of the rotor blade from a first resin material, placing the first spar cap within a first shell mold of the rotor blade, and infusing a second resin material into the first shell mold to form a first shell member of the rotor blade. Thus, at least a portion of the first spar cap is infused within the first shell member. The second resin material is different than the first resin material. The method also includes infusing the second resin material into a second shell mold to form a second shell member of the rotor blade. Another step includes bonding the first and second shell members together so as to form the rotor blade. Document <CIT> is another prior art document disclosing a method of manufacturing a wind turbine blade.

It is one of the objects of the invention to provide a method of manufacturing a wind turbine blade capable of being easily manufactured while improving structural strength.

To this end, the invention provides a method in accordance with claim <NUM>. Advantageous embodiments are subject to the dependent claims and the description and the drawings.

According to an aspect of the, there is provided a method of manufacturing a wind turbine blade including: performing spar cap formation in which a first-type spar cap having a structure in which support plates including reinforcing fibers are stacked and a second-type spar cap including reinforcing fiber sheets are formed, performing shell formation in which a pressure side shell and a suction side shell are formed by injecting a resin in a state in which the first-type spar cap, the second-type spar cap, and a core panel are disposed between an inner skin and an outer skin, and performing shell assembly in which the pressure side shell is joined to the suction side shell.

The blade may have an airfoil cross-section and may include a pressure side, a suction side, a leading edge through which the wind enters, and a trailing edge through which the wind exits. In the performing shell formation, the second-type spar cap may be disposed on the pressure side.

In the performing shell formation, the second-type spar cap may be disposed adjacent to the trailing edge.

In the performing shell formation, the first-type spar cap may be disposed adjacent to the leading edge on the pressure side.

In the performing shell formation, the first-type spar cap may be disposed adjacent to the leading edge on the suction side.

In the performing shell formation, the first-type spar cap may be disposed adjacent to the trailing edge on the suction side.

In the performing shell formation, the first-type spar cap may include a plurality of first-type spar caps disposed each of a portion adjacent to the leading edge on the pressure side and portions adjacent to the leading edge and the trailing edge on the suction side, and the second-type spar cap may be disposed adjacent to the trailing edge on the pressure side.

The performing shell formation may include placing the outer skin on a main mold, placing the first-type spar cap, the second-type spar cap and the core panel on the outer skin, placing the inner skin above them, wrapping the main mold with a film-type cover, and connecting an inside of the cover to a vacuum pump to inject the resin in a state in which a vacuum pressure is applied to a space between the cover and the main mold.

Each of the outer skin and the inner skin may be formed of a glass fiber sheet or a carbon fiber sheet.

Each of the outer skin and the inner skin may be formed of a hybrid fiber sheet including glass and carbon fibers.

According to the invention, in the performing spar cap formation, the second-type spar cap is formed by stacking the reinforcing fiber sheets on a mold and injecting a resin in a state in which the reinforcing fiber sheets are wrapped with a cover.

The reinforcing fiber sheets may be glass fiber sheets.

The resin may be a polyester resin or an epoxy resin.

According to the invention, in the performing spar cap formation, the first-type spar cap is formed by stacking the support plates on a mold and injecting a resin into the mold to bond the support plates by a resin bonding layer.

The support plates may include carbon fibers.

The above and other aspects will become more apparent from the following description of the exemplary embodiments with reference to the accompanying drawings, in which:.

Various modifications and different embodiments will be described below in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the invention. It should be understood, however, that the present invention is not intended to be limited to the specific embodiments.

The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of the disclosure. It will be further understood that the terms "comprises/includes" and/or "have/has" when used in this specification, specify the presence of stated features, integers, steps, operations, components, parts, and/or combinations thereof, but do not preclude the presence or addition of one or more of other features, integers, steps, operations, components, parts, and/or combinations thereof.

Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings. It should be noted that like reference numerals refer to like parts throughout various drawings and exemplary embodiments. In certain embodiments, a detailed description of functions and configurations well known in the art may be omitted to avoid obscuring appreciation of the disclosure by those skilled in the art. For the same reason, some components may be exaggerated, omitted, or schematically illustrated in the accompanying drawings.

<FIG> is a perspective view illustrating the wind turbine according to an exemplary embodiment.

Referring to <FIG>, the wind turbine <NUM> includes a tower <NUM>, a nacelle <NUM>, and a rotor <NUM>. The wind turbine <NUM> may be installed on land or offshore, and may be a direct type with or without a gearbox.

The tower <NUM> is installed upright at a certain height on the ground or offshore and supports the nacelle <NUM> and the rotor <NUM>. The tower <NUM> may have a tubular shape that increases in diameter from top to bottom. In this case, the tower <NUM> may have a multistage form in which a plurality of tubular members are stacked. For example, the inside of the tower <NUM> may be provided with a stair, a conveyor, or an elevator for transporting a worker or a work tool for maintenance.

The nacelle <NUM> may be installed on the tower <NUM> to be able to yaw with respect to the tower <NUM>. In other words, the nacelle <NUM> may be positioned on the tower <NUM> and may be rotatably coupled to the tower <NUM>.

The nacelle <NUM> may be a housing for accommodating a generator or the like, and may have a hexahedral shape. However, the shape of the nacelle <NUM> is not necessarily limited thereto, and the nacelle <NUM> may be formed in a cylinder, an ellipsoid, or the like.

The rotor <NUM> includes a hub <NUM> and a plurality of blades <NUM>, and the hub <NUM> is rotatably installed on a front surface of the nacelle <NUM>. The plurality of blades <NUM> are coupled to an outer peripheral surface of the hub <NUM> while being spaced apart from each other at predetermined intervals in a circumferential direction. Although <FIG> illustrates that three blades <NUM> are installed on one hub <NUM>, but the present disclosure is not limited thereto.

The plurality of blades <NUM> are rotated about a central axis of the hub <NUM> by wind. Each of the blades <NUM> has a streamlined cross-section in a width direction, and a space may be formed therein.

<FIG> is a perspective view illustrating one blade according to the exemplary embodiment. <FIG> is a cross-sectional view of the blade according to the exemplary embodiment.

Referring to <FIG> and <FIG>, the blade <NUM> includes a cylindrical part connected to the hub <NUM> and has an airfoil cross-section outwardly.

The blade <NUM> having an airfoil cross-section includes a pressure side S1 and a suction side S2. The rotor <NUM> is rotated by the difference in pressure between the suction side S2 and the pressure side S1. The blade <NUM> includes a leading edge LE through which the wind enters, and a trailing edge TE through which the wind exits. The blade <NUM> has a relatively flat extension adjacent to the leading edge LE and a large bend adjacent to the trailing edge TE.

The blade <NUM> may include an outer skin <NUM>, core panels <NUM>, an inner skin <NUM>, spar caps SC, and shear webs <NUM>. The outer skin <NUM>, the core panels <NUM>, the inner skin <NUM>, and the spar caps SC form a pressure side shell <NUM> and a suction side shell <NUM>, and the pressure side shell <NUM> and suction side shell <NUM> are joined to form the blade <NUM>.

The core panels <NUM> are positioned between the inner skin <NUM> and the outer skin <NUM>. The blade <NUM> may be in a form of a sandwich panel in which the inner skin <NUM> and the outer skin <NUM> surround the core panels <NUM> and the spar caps SC.

The inner skin <NUM> and the outer skin <NUM> are made of fiber-reinforced plastic (FRP). For example, the inner skin <NUM> and the outer skin <NUM> may be made of glass-fiber-reinforced plastic (GFRP) or carbon-fiber-reinforced plastic (CFRP). The core panels <NUM> may be made of balsa wood or foam. The core panels <NUM> may be made of urethane foam.

The spar caps SC are respectively positioned between the core panels <NUM> to enhance the rigidity of the blade <NUM>. Each of the spar caps SC may be in a form of a plate having a predetermined width extending in a longitudinal direction of the blade <NUM>. The spar caps SC are spaced apart from each other in a thickness direction of the blade <NUM> and are installed on the suction side S2 and the pressure side S1.

The shear webs <NUM> connect the spar caps SC installed on the pressure side S1 and the spar caps SC installed on the suction side S2, and are installed upright in the thickness direction of the blade <NUM>. For example, two shear webs <NUM> spaced apart from each other in the width direction of the blade <NUM> may be installed in the blade <NUM>. The shear webs <NUM> may extend in the longitudinal direction of the blade <NUM>. Each of the shear webs <NUM> may be in the form of a sandwich panel and may support a load by connecting the associated spar caps SC. The shear web <NUM> may have a structure in which a foam or wood is inserted between metal plates or fiber-reinforced plastic plates.

<FIG> is a cross-sectional view illustrating one first-type spar cap according to the exemplary embodiment. <FIG> is a cross-sectional view illustrating one second-type spar cap according to the exemplary embodiment.

Referring to <FIG>, the spar caps SC include a first-type spar cap <NUM> and a second-type spar cap <NUM>. The first-type spar cap <NUM> has a structure in which support plates <NUM> including reinforcing fibers are stacked, and the second-type spar cap <NUM> has a structure in which a resin is impregnated with reinforcing fiber sheets <NUM>.

The first-type spar cap <NUM> includes support plates <NUM> and a resin bonding layer <NUM> for fixing the support plates <NUM>. Each of the support plates <NUM> may be an elongated plate formed by drawing a carbon fiber and a resin. The strength of the first-type spar cap <NUM> can be improved because the first-type spar cap <NUM> is formed by stacking the support plates <NUM> including the carbon fibers.

The second-type spar cap <NUM> includes reinforcing fiber sheets <NUM> and a resin body <NUM> for fixing the reinforcing fiber sheets <NUM>, and may be made of glass-fiber-reinforced plastic. Here, the reinforcing fiber sheet <NUM> may be glass fiber sheets.

The second-type spar cap <NUM> may have a structure in which a polyester resin or an epoxy resin is impregnated with the reinforcing fiber sheets <NUM> so that the reinforcing fiber sheets <NUM> are integrally formed with the resin body <NUM>.

The first-type spar cap <NUM> is disposed on each of a portion adjacent to the leading edge LE on the pressure side S1 and portions adjacent to the leading edge LE and the trailing edge TE on the suction side S2. On the other hand, the second-type spar cap <NUM> is disposed adjacent to the trailing edge TE on the pressure side S1. That is, three first-type spar caps <NUM> and one second-type spar caps <NUM> may be installed on one blade <NUM>.

The shear web <NUM> disposed adjacent to the trailing edge TE has one end coupled to an associated one of the first-type spar caps <NUM> and the other end coupled to the second-type spar cap <NUM>. On the other hand, the shear web <NUM> disposed adjacent to the leading edge LE has both ends coupled to associated ones of the first-type spar caps <NUM>. As described above, according to the first exemplary embodiment, the spar caps SC having different structures may be disposed on the ends of one shear web <NUM> to support the blade <NUM>.

Hereinafter, a method of manufacturing a blade according to a first exemplary embodiment will be described.

<FIG> is a flowchart for explaining a method of manufacturing a blade according to the first exemplary embodiment. <FIG> is a view illustrating a process of manufacturing the first-type spar cap according to the first exemplary embodiment. <FIG> is a view illustrating a process of manufacturing the second-type spar cap according to the first exemplary embodiment. <FIG> is a view illustrating a shell formation process according to the first exemplary embodiment.

Referring to <FIG>, the method of manufacturing a blade according to the first exemplary embodiment includes a spar cap formation step S101, a shell formation step S102, and a shell assembly step S103.

In the spar cap formation step S101, a first-type spar cap <NUM> having a structure in which support plates <NUM> including reinforcing fibers are stacked and a second-type spar cap <NUM> including reinforcing fiber sheets <NUM> are formed. The first-type spar cap <NUM> and the second-type spar cap <NUM> may be formed simultaneously or separately.

As illustrated in <FIG>, the spar cap formation step S101 includes a support plate stacking step of stacking a plurality of support plates <NUM> on a mold <NUM>, a guide block installation step of installing detachable guide blocks <NUM> at side ends of the stacked support plates <NUM>, and a resin injection step of injecting the resin stored in a container <NUM> into the mold <NUM> to bond the support plates <NUM> by a resin bonding layer <NUM>. If the stacked support plates <NUM> are bonded by the resin bonding layer <NUM>, the first-type spar cap <NUM> is formed. Here, the resin may be a polyester resin or an epoxy resin.

As illustrated in <FIG>, the spar cap formation step S101 includes a reinforcing fiber sheet stacking step of stacking a plurality of reinforcing fiber sheets <NUM> on a mold <NUM>, a sheet wrapping step of wrapping the stacked reinforcing fiber sheets <NUM> with a film-type cover <NUM>, and a vacuum resin injection step of discharging the air within the cover <NUM> by a vacuum pump <NUM> while injecting the resin stored in a container <NUM> into the mold <NUM>. Here, the reinforcing fiber sheets <NUM> may be glass fiber sheets, and the resin may be a polyester resin or an epoxy resin.

Accordingly, the second-type spar cap <NUM> is formed by fixing the glass fiber sheets inside the resin body <NUM> while preventing pores from being formed between the reinforcing fiber sheets <NUM>.

In the shell formation step S102, in a state in which the first-type spar cap <NUM>, the second-type spar cap <NUM>, and core panels <NUM> are disposed between an inner skin <NUM> and an outer skin <NUM>, an epoxy resin or the like is injected to form a pressure side shell <NUM> and a suction side shell <NUM>.

As illustrated in <FIG>, the shell formation step S102 may include an outer skin placement step of placing the outer skin <NUM> on a main mold <NUM>, a component placement step of placing a plurality of spar caps <NUM>, <NUM> and core panels <NUM>, an inner skin placement step of placing the inner skin <NUM> above them, a component wrapping step of wrapping the main mold <NUM> with a film-type cover <NUM>, and a resin injection step of connecting the inside of the cover <NUM> to a vacuum pump <NUM> to inject a resin in a state in which a vacuum pressure is applied to the space between the cover <NUM> and the main mold <NUM>.

Here, the outer skin <NUM> and the inner skin <NUM> may each be formed of a glass fiber sheet or a carbon fiber sheet. Alternatively, each of the outer skin <NUM> and the inner skin <NUM> may be formed of a hybrid fiber sheet including glass and carbon fibers.

If the resin is injected, the resin is bonded to the outer skin <NUM> and the inner skin <NUM>. In addition, the outer skin <NUM> and the inner skin <NUM> may be integrally fixed to the core panels <NUM> and the spar caps <NUM>, <NUM> by the resin.

In the shell formation step S102, the first-type spar cap <NUM> is disposed on each of a portion adjacent to the leading edge LE on the pressure side S1 and portions adjacent to the leading edge LE and the trailing edge TE on the suction side S2, and the second-type spar cap <NUM> is disposed adjacent to the trailing edge TE on the pressure side S1.

In the shell assembly step S103, the pressure side shell <NUM> and the suction side shell <NUM> are joined to each other, and the first-type spar cap <NUM> or the second-type spar cap <NUM> is coupled to an associated shear web <NUM>. Here, one of the first-type spar caps <NUM> and the second-type spar cap <NUM> are coupled to the shear web <NUM> disposed adjacent to the trailing edge TE, and the other first-type spar cap <NUM> is coupled to the shear web <NUM> disposed adjacent to the leading edge LE.

Because the reinforcing fiber sheets <NUM> made of glass fibers have flexibility, the reinforcing fiber sheets <NUM> may easily reflect the bent shape and the twisted shape of the blade <NUM>. However, it may be difficult for the support plates <NUM> to reflect the bent part of the blade <NUM> because the support plates <NUM> are relatively inflexible and are not easily bent.

According to the first exemplary embodiment, because the second-type spar cap <NUM> formed by impregnating the resin with the reinforcing fiber sheets <NUM> is disposed adjacent to the trailing edge TE of the pressure side S1, the freedom of design of the blade <NUM> can be improved by freely forming the shape of the trailing edge TE.

In addition, because the first-type spar caps <NUM> each having a structure in which the support plates <NUM> are stacked are disposed on the side of the leading edge LE extending in a straight line receiving a relatively large load, the strength of the blade <NUM> can be improved. Furthermore, because one of the first-type spar caps <NUM> in which the support plates <NUM> are stacked is disposed on the portion adjacent to the trailing edge TE on the suction side S2 which is relatively less bent compared to the pressure side S1, the strength of the blade <NUM> can be improved.

Hereinafter, a method of manufacturing a blade according to a second exemplary embodiment will be described. <FIG> is a cross-sectional view of one blade according to the second exemplary embodiment.

Referring to <FIG>, because the method of manufacturing a blade according to the second exemplary embodiment has the same process as the method of manufacturing a blade according to the first exemplary embodiment except for a shell formation step, a redundant description will be omitted.

In the shell formation step, in a state in which first-type spar caps <NUM>, second-type spar caps <NUM>, and core panels <NUM> are disposed between an inner skin <NUM> and an outer skin <NUM>, a resin is injected to form a pressure side shell <NUM> and a suction side shell <NUM>.

In the shell formation step, the first-type spar caps <NUM> are disposed adjacent to the leading edge LE on the pressure side S1 and adjacent to the leading edge LE on the suction side S2, respectively. In the shell formation step, the second-type spar caps <NUM> are disposed adjacent to the trailing edge TE on the pressure side S1 and adjacent to the trailing edge TE on the suction side S2, respectively. Accordingly, the first-type spar caps <NUM> are disposed on the side of the leading edge LE of the blade <NUM>, and the second-type spar caps <NUM> are disposed on the side of the trailing edge TE of the blade <NUM>.

According to the second exemplary embodiment, because the second-type spar caps <NUM> each formed by impregnating the resin with the reinforcing fiber sheets <NUM> are disposed adjacent to the trailing edge TE, the freedom of design of the blade <NUM> can be improved by freely forming the shape of the trailing edge TE. In addition, because the first-type spar caps <NUM> each having a structure in which the support plates <NUM> are stacked are disposed on the side of the leading edge LE extending in a straight line receiving a relatively large load, the strength of the blade <NUM> can be improved.

Hereinafter, a method of manufacturing a blade according to a third exemplary embodiment will be described. <FIG> is a view illustrating a process of manufacturing one first-type spar cap according to the third exemplary embodiment.

Referring to <FIG>, a spar cap formation step includes a support plate stacking step of stacking a plurality of support plates <NUM> on a mold <NUM>, a guide block installation step of installing detachable guide blocks <NUM> at the side ends of the stacked support plates <NUM>, and a resin injection step of injecting the resin stored in a container <NUM> into the mold <NUM> to bond the support plates <NUM> by the resin.

The support plate stacking step is performed such that an outer support plate <NUM> has a smaller width W11 than an inner support plate <NUM>. That is, the support plate <NUM> disposed adjacent to the outer skin <NUM> of the blade has a smaller width than the inner support plate <NUM>.

Accordingly, because the first-type spar cap <NUM> is shaped to coincide with the outer surface of the blade curved in the form of an arc, the blade can be supported more stably.

As described above, according to the exemplary embodiments, the freedom of design of the blade can be improved because some spar caps include the reinforcing fiber sheets, and the strength of the blade can be improved because other spar caps each have a structure in which the support plates including the reinforcing fibers are stacked.

Claim 1:
A method of manufacturing a wind turbine blade (<NUM>), comprising:
performing spar cap formation which includes:
forming a first-type spar cap (<NUM>, <NUM>) by stacking support plates (<NUM>, <NUM>) including reinforcing fibers on a mold (<NUM>, <NUM>) and injecting a resin into the mold (<NUM>, <NUM>) to bond the support plates (<NUM>, <NUM>) by a resin bonding layer (<NUM>), and
forming a second-type spar cap (<NUM>, <NUM>) by stacking reinforcing fiber sheets (<NUM>) on a mold (<NUM>, <NUM>, <NUM>) and injecting a resin in a state in which the reinforcing fiber sheets (<NUM>) are wrapped with a cover (<NUM>);
performing shell formation in which a pressure side shell (<NUM>) and a suction side shell (<NUM>) are formed by injecting a resin in a state in which the first-type spar cap (<NUM>, <NUM>), the second-type spar cap (<NUM>, <NUM>), and a core panel (<NUM>) are disposed between an inner skin (<NUM>) and an outer skin (<NUM>), the inner skin (<NUM>) and the outer skin (<NUM>) being made of fiber-reinforced plastic; and
performing shell assembly in which the pressure side shell (<NUM>) is joined to the suction side shell (<NUM>).