Hollow rotary vane

Abstract

To provide a rotary vane that can be manufactured at an inexpensive price while being strong and rigid enough as a rotary vane, and is light-weight on the whole and also suitable for energy saving.SOLUTION: There is provided a hollow rotary vane that has a top-surface skin imitating a top surface of a vane molded out of a fiber-reinforced composite material, a reverse-surface skin imitating a reverse surface of the vane molded out of the fiber-reinforced composite material, and a shear wave interposed between the top-surface skin and reverse-surface skin to support them, wherein the top-surface skin and reverse-surface skin have a fitting part for fitting the shear wave and a step part to mesh when superposed on their inner layer-side surfaces, and the shear web is fitted to the fitting part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a hollow rotating wing, and more particularly to a hollow rotating wing that can be suitably used for a flying vehicle for UAM (Urban Air Mobility), so-called "flying car".

Background Art

[0002] For the purpose of alleviating traffic congestion in urban areas and ensuring transportation means to remote islands and the like, the development of flying vehicles for UAM is underway. In this process, how to design a rotating wing for a flying vehicle for UAM has become one of the problems.

[0003] Conventional rotating wings for general aviation means are of two types: a high-performance type that has obtained aircraft certification for Cessna aircraft and a non-certified / low-cost type for drones. However, since the flying vehicle for UAM is a relatively new field, the rotating wing for the flying vehicle for UAM is considered not to be suitable either in terms of cost or reliability. However, since the flying vehicle for UAM passes over urban areas, it is considered that safety standards equivalent to those of aircraft will be set. In actual design, in addition to the requirements for strength, rigidity, and cost, promotion of weight reduction and energy saving, and further improvement in performance and molding are considered important.

[0004] Looking at the conventionally known rotary wings from the above viewpoints, for example, Patent Documents 1 to 3 can be cited. Patent Document 1 discloses a rotary wing for an unmanned aircraft having a core portion including a foam impregnated with a thermosetting resin inside an outer skin impregnated with a thermosetting resin in carbon fiber. Patent Document 2 discloses a method of arranging a foaming agent between the dorsal part and the ventral part of a composite material wing made of a reinforcing fiber and a resin, and heating and expanding the foaming agent to form a composite material wing composed of a dorsal laminate, a ventral laminate, and an internal foaming agent. Patent Document 3 discloses a method of expanding a bag body arranged between first and second composite fiber layers to form a hollow blade for a wind turbine. Patent Documents 4 and 5 disclose a hollow blade structure for a windmill including fitting portions of a skin and a shear web. Patent Document 6 discloses a rotor blade structure for a helicopter in which upper and lower skins are adhered and joined.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the structures and methods disclosed in the above-mentioned Patent Documents 1 and 2, since the inside of the rotor blade is composed of a foam or a foaming agent, the weight of the entire blade is reduced. However, since the foam or foaming agent provided inside remains as it is even after the blade is formed, there is a limit to weight reduction, and the effect of weight reduction is insufficient. In this regard, in the methods disclosed in Patent Documents 3 to 6, since the inside of the blade is formed hollow, the weight of the entire blade can be reduced. However, since it is a hollow blade for a wind turbine or a helicopter, the size, use, overall shape, and structure are basically greatly different from those of a rotor blade for a UAM aircraft, and it is difficult to apply it to a rotor blade for a UAM aircraft.

[0007] An object of the present invention is to provide a hollow rotor blade that can be suitably applied particularly to a rotor blade for a UAM aircraft, can meet the requirements of desirable strength and rigidity and low cost, can promote weight reduction and energy saving, and can further improve performance and molding.

Means for Solving the Problems

[0008] In order to solve such problems, the present invention employs any of the following means. That is, 〔1〕An upper skin that mimics the upper surface of a blade formed of a fiber-reinforced composite material, a lower skin that mimics the lower surface of the blade formed of a fiber-reinforced composite material, and a shear web that exists between the upper skin and the lower skin and supports them. The upper skin and the lower skin have a fitting portion for fitting the shear web to the inner layer side surface and a stepped portion that meshes when overlapped, and the shear web is fitted to the fitting portion. A hollow rotor blade. 〔2〕The hollow rotor blade according to 〔1〕, wherein the dihedral angle of two planar portions adjacent to the stepped portion exceeds 90°. 〔3〕The hollow rotor blade according to 〔1〕 or 〔2〕, characterized in that the fitting portion has a foam adhesive layer, and the shear web is adhered to the upper skin and the lower skin through the foam adhesive layer, or the stepped portion has a foam adhesive layer, and the upper skin and the lower skin are adhered through the foam adhesive layer. 〔4〕 The hollow rotating blade according to 〔3〕, wherein the thickness of the foamed adhesive layer is 0.05 mm or more and 0.4 mm or less. 〔5〕 The hollow rotating blade according to any one of 〔1〕 to 〔4〕, wherein the reinforcing fibers contained in the fiber-reinforced composite material constituting the fitting portion or the stepped portion are discontinuous fibers. 〔6〕 The hollow rotating blade according to 〔5〕, wherein the fitting portion is formed of a fiber-reinforced composite material made of a thermosetting resin or a thermoplastic resin in which discontinuous reinforcing fibers are dispersed therein. 〔7〕 The hollow rotating blade according to any one of 〔1〕 to 〔6〕, wherein the shear web has a bent portion in a top view thereof. 〔8〕 The hollow rotating blade according to any one of 〔1〕 to 〔7〕, wherein the volume content ratio of the reinforcing fibers contained in the skin and the volume content ratio of the reinforcing fibers contained in the shear web are both 10% or more greater than the volume content ratio of the reinforcing fibers contained in the fitting portion.

Advantages of the Invention

[0009] According to the hollow rotating blade of the present invention, it is possible to manufacture at low cost while ensuring the strength and rigidity required as a rotating blade, and it can be a rotating blade that is lightweight as a whole and suitable for energy saving.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0012] The hollow rotating wing of the present invention has at least an upper skin imitating the upper surface of the wing formed of a fiber-reinforced composite material, a lower skin imitating the lower surface of the wing formed of a fiber-reinforced composite material, and a shear web. Further, the upper skin and the lower skin have a fitting portion for fitting the shear web to the inner layer side surface and a stepped portion that meshes when the upper skin and the lower skin are overlapped. Note that the inner layer side surface is the surface on the side farther from the outer surface of the rotating wing. FIG. 1 shows an embodiment of the hollow rotating wing of the present invention used as a propeller blade. FIG. 1 shows a top view of the hollow rotating wing 1, with the right side of the paper being the tip 2a and the left side of the paper being the root 2b.

[0013] The A-A' cross-section of this hollow rotating wing 1 (that is, the cross-section in the direction orthogonal to the longitudinal direction of the hollow rotating wing 1) is shown in FIG. 2. This hollow rotating wing 1 has an upper skin 3a imitating the upper surface of the wing, a lower skin 3b imitating the lower surface of the wing, and a shear web 4. The upper skin 3a is provided with stepped portions 5a and 6a that mesh when the lower skin is overlapped and a fitting portion 7a for fitting the shear web 4. The lower skin 3b is provided with stepped portions 5b and 6b that mesh when the upper skin is overlapped and a fitting portion 7b for fitting the shear web 4 corresponding to the upper skin. The provision of the fitting portions 7a and 7b enables easy positioning of the shear web 4 and can increase the load-bearing capacity of the joint portion. Further, the stepped portions 5a and 5b are arranged on the trailing edge side, and the stepped portions 6a and 6b are arranged on the leading edge side. When the opposing skins are overlapped, they have a shape such that the stepped surfaces are in close contact, facilitating positioning.

[0014] Figure 3 is an enlarged view of the trailing edge side of Figure 2, and Figure 4 is an enlarged view of the leading edge side of Figure 2. The upper skin and the lower skin have stepped portions that mesh with each other. In the present invention, as shown in Figures 3 and 4, the dihedral angle (for example, α in Figure 3 and β in Figure 4) of the two adjacent planar portions of the stepped portion exceeds 90°. That is, there are no two adjacent planes with an acute dihedral angle. By adopting such a design, the joint area can be increased and the peel load can be increased. In addition, when the upper skin and the lower skin are superposed and molded, they can be easily superposed, and the moldability can be improved. Further, the presence of the stepped portions (5a, 5b, 6a, 6b) can facilitate the positioning and joining of the upper and lower skins. Also, the stepped portions (6a, 6b) on the leading edge side can also have impact resistance performance when a flying object such as a bird collides. In the figure, the stepped portions are represented by a plurality of planes, but as long as the upper skin and the lower skin can mesh with each other, those including curved surfaces may be used.

[0015] In the present invention, the upper skin and the lower skin have fitting portions for fitting the shear web. The lower limit of the gap (that is, the distance) between the upper skin or the lower skin and the shear web in this fitting portion is preferably 0.05 m or more, more preferably 0.07 mm or more, and even more preferably 0.1 mm or more. If it is less than 0.05 mm, the shear web may not fit into the fitting portion and the intended outer shape may not be realized. On the other hand, the upper limit of the gap is preferably 0.4 mm or less, more preferably 0.35 mm or less, and even more preferably 0.3 mm or less. If it exceeds 0.4 mm, the load-bearing capacity of the shear web will decrease, the stiffening effect by the shear web will be reduced, and the intended mechanical properties of the propeller blade may not be realized.

[0016] In the present invention, the methods for joining the upper skin and the lower skin including the stepped portion, joining the upper skin and the shear web, and joining the lower skin and the shear web include methods such as fusion, welding, and methods using adhesives, and are not particularly limited, but adhesion using adhesives, welding using thermoplastic resins, etc. can be applied. Among them, it is preferable that joining is performed using a foaming adhesive that foams with heat during molding and can firmly fill the gap between the two members.

[0017] Since the stepped portions and fitting portions provided on the inner layer side surfaces of the upper skin and the lower skin have complex shapes, it is preferably composed of a fiber-reinforced composite material reinforced with discontinuous fibers from the viewpoint of moldability. The fiber length of the discontinuous fibers is preferably 50 mm or less, more preferably 20 mm or less, and even more preferably 5 mm or less. If it exceeds 50 mm, a resin-rich portion with a low probability of fiber presence may occur, leading to possible molding defects. On the other hand, the lower limit of the fiber length of the discontinuous fibers is preferably 0.1 mm or more, more preferably 0.5 mm or more, and even more preferably 1 mm or more. If it is less than 0.1 mm, the reinforcing effect by the discontinuous fibers is small, and there is a risk of becoming a starting point for fracture.

[0018] Also, the fitting portion is preferably formed of a fiber-reinforced composite material made of a thermosetting resin or a thermoplastic resin in which discontinuous reinforcing fibers are dispersed therein.

[0019] The upper skin, the lower skin, and the shear web constituting the hollow rotating blade of the present invention are preferably composed of a fiber-reinforced composite material reinforced with continuous reinforcing fibers. However, as described above, in the upper skin and the lower skin, the stepped portions and the fitting portions are preferably composed of a fiber-reinforced composite material reinforced with discontinuous fibers. The reinforcing fibers and resins that are components of the fiber-reinforced composite material will be described later.

[0020] When the shear web constituting the hollow rotating blade of the present invention is formed of a fiber-reinforced composite material, the volume fraction (Vfa) of the reinforcing fibers contained in the skin and the volume fraction (Vfb) of the reinforcing fibers contained in the shear web are preferably larger than the volume fraction (Vfc) of the reinforcing fibers contained in the fitting portion. The differences between Vfa (volume %), Vfb (volume %), and Vfc (volume %), specifically (Vfa - Vfc) and (Vfb - Vfc), are preferably both 10% or more, more preferably 15% or more, and even more preferably 20% or more. If it is less than 10%, there may be a fiber-unfilled portion or it may be impossible to obtain the desired mechanical properties. Although there is no particular limitation as the upper limit, it is preferably 50% or less.

[0021] The hollow rotating blade of the present invention has a hollow portion in the space sandwiched between the upper skin and the lower skin. The hollow portion formed inside (refer to reference numerals 8a and 8b in FIG. 2) is a hollow portion, so that the entire rotating blade is lighter than a configuration containing a foaming agent or a foam inside. Along with this, it becomes possible to reduce the rotational driving power (for example, miniaturize the drive motor), so that it becomes possible to promote energy saving and reduce the manufacturing cost of the aircraft. Further, since the hollow rotating blade 1 is composed of a composite material made of resin and reinforcing fibers, it is possible to ensure sufficiently high strength and rigidity even if the blade thickness (wall thickness of the blade) is kept small. In particular, when carbon fibers are used as the reinforcing fibers, it is possible to ensure particularly high strength and rigidity. The volume of the hollow portion is preferably 50% or more when the volume of the entire blade is 100%. On the other hand, in view of having sufficient mechanical properties, the volume of the hollow portion is preferably 80% or less when the volume of the entire blade is 100%.

[0022] The blade length of the hollow rotating blade of the present invention is preferably 2 m or less, more preferably 1.7 m or less, and even more preferably 1.5 m or less. If it exceeds 2 m, productivity may be inferior and it may lead to an increase in cost. On the other hand, the lower limit of the blade length is preferably 0.5 m or more, more preferably 0.6 m or more, and even more preferably 0.7 m or more. If it is less than 0.5 m, the weight reduction effect due to the hollow is small, and it may lead to an increase in cost in obtaining the required lift force.

[0023] In the wing length direction X starting from the wing root part 2b of the hollow rotating wing of the present invention, the hollow ratio of the hollow part in the wing thickness direction of an arbitrary point in the range from 0.2×L to 0.8×L in the wing length direction is preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more. If it is less than 50%, there is a concern that the weight reduction effect due to the hollow structure becomes small.

[0024] The shape of the shear web used in the present invention is preferably plate-shaped. When it is plate-shaped, there is no particular limitation on its shape in a top view, and it may be linear or curved, but it preferably has a bent portion. Note that the top view is the direction from the fitting portion of the upper skin to the fitting portion of the lower skin as shown in FIGS. 1, 5, and 6. FIGS. 5 and 6 show examples of arrangements of shear webs different from the example of FIG. 1. Also, the shear web 4 in FIG. 5 has a zigzag line shape where the bent portion is bent, and the shear web 4 in FIG. 6 has a waveform shape where the bent portion is a curved surface. The shape of the shear web in a top view can be designed to have an arbitrary shape according to the required rigidity and required strength of the hollow rotating wing.

[0025] Further, in the hollow rotating wing, it is preferable that one or more shear webs extending in the wing length direction are provided in the hollow part. In this case, when viewed in a vertical cross-section in the wing length direction, two or more regions partitioned by the shear web can be recognized. The example shown in FIG. 2 is an example having a shear web 4 extending in the wing length direction, and two regions 8a and 8b can be recognized in the cross-sectional view. By providing such a shear web 4, it becomes possible to increase the strength and rigidity of the rotating wing as a whole. The number of shear webs extending in the wing length direction can be set according to the required rigidity and required strength of the hollow rotating wing, but from the viewpoints of moldability and cost, one is preferable.

[0026] In addition, when viewed as a rectangle with the smallest area circumscribing the projection diagram obtained by irradiating parallel light rays perpendicular to the rotation plane of the hollow rotating blade, it is preferable from the viewpoint of enhancing the rigidity of the hollow rotating blade that the shear webs exist over 70% or more of the length of the long side in the long side direction (blade length direction). Also, in the short side direction (blade width direction), it is preferable that the shear webs exist over 30% or more of the length of the short side of the rectangle with the smallest area circumscribing the projection diagram. In this case, when there are a plurality of shear webs, the ratio occupied by the shear webs in the long side direction shall be determined based on the perspective view of all the shear webs. Further, it is preferable that the fitting portion exists so as to cover the entire contact surface between the shear web and the skin.

[0027] Hereinafter, examples of the material used for the hollow rotating blade of the present invention and the method for manufacturing the hollow rotating blade will be described with examples.

[0028] <Reinforcing fiber> As the fiber used for the fiber-reinforced composite material constituting the hollow rotating blade of the present invention, there is no limitation as long as it is a fiber having a reinforcing effect, but it is preferable to use carbon fiber, glass fiber, aramid fiber, or metal fiber. Among them, it is particularly preferable to use carbon fiber. The carbon fiber is not particularly limited. For example, polyacrylonitrile (PAN)-based, pitch-based, and rayon-based carbon fibers can be preferably used from the viewpoints of improving mechanical properties and weight reduction effect, and these may be used alone or in combination of two or more. Among them, PAN-based carbon fiber is more preferable from the viewpoint of the balance between the strength and elastic modulus of the obtained hollow rotating blade.

[0029] The single fiber diameter of the reinforcing fiber is preferably 0.5 μm or more, more preferably 2 μm or more, and even more preferably 4 μm or more. Also, the single fiber diameter of the reinforcing fiber is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The strand strength of the reinforcing fiber is preferably 3.0 GPa or more, more preferably 4.0 GPa or more, and even more preferably 4.5 GPa or more. The strand elastic modulus of the reinforcing fiber is preferably 200 GPa or more, more preferably 220 GPa or more, and even more preferably 240 GPa or more. If the strand strength or elastic modulus of the reinforcing fiber is within this range, the mechanical properties of the hollow rotating blade can be enhanced.

[0030] The reinforcing fiber may be either continuous fiber (long fiber) or discontinuous fiber (short fiber). Also, it may be in the form of a fabric or knitted fabric such as an orthogonal biaxial fabric, non-crimp fabric, or braiding substrate, or a multi-axial knitted structure.

[0031] <Matrix resin> The resin used in the fiber-reinforced composite material constituting the hollow rotating blade of the present invention is used as a matrix material that encapsulates the reinforcing fiber. The matrix resin is not particularly limited, and it is possible to use a thermoplastic resin or a thermosetting resin. For example, thermosetting resins such as epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, epoxy acrylate resin, urethane acrylate resin, phenoxy resin, alkyd resin, urethane resin, maleimide resin, cyanate resin, and thermoplastic resins such as polyamide, polyacetal, polyacrylate, polysulfone, ABS, polyester, acrylic, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene, polypropylene, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), liquid crystal polymer, PVC, fluorine-based resins such as polytetrafluoroethylene, and silicone can be mentioned. Also, copolymers and modified products of the polymers forming these resins can be used. Also, using a plurality of types of resins is not prohibited.

[0032] <Method for manufacturing a hollow rotary wing> Typical manufacturing processes of the hollow rotary wing of the present invention include: (1) a skin forming process, (2) a process of forming fitting portions and stepped portions on the skin, (3) a shear web forming process, and (4) a joining process of the skin and the shear web. Note that these processes can be performed in one process (for example, forming the skin and forming the fitting portions and stepped portions on the skin simultaneously), but for convenience, they will be described separately. Specific examples will be given for each process and described below.

[0033] (1) Skin forming process It is convenient to form using a sheet-shaped fiber-reinforced composite material. In particular, as the sheet-shaped fiber-reinforced composite material, a thermosetting prepreg or a thermoplastic prepreg known as an intermediate base material in which reinforcing fibers are impregnated with resin in advance can be preferably used. It is also possible to use a fabric or braiding base material that does not contain resin or an NCF (non-crimp fabric) by impregnating it with resin during the forming process. As the forming method, autoclave molding, press molding, transfer molding, AFP (automated fiber placement), stamping molding, etc. can be applied.

[0034] During forming, by using a mold that mimics the upper surface of the wing and a mold that mimics the lower surface of the wing, an upper surface skin that mimics the upper surface of the wing and a lower surface skin that mimics the lower surface of the wing can be obtained.

[0035] Here, the prepreg is composed of reinforcing fibers and a matrix resin. The lower limit of the volume content ratio of the reinforcing fibers contained in the prepreg is preferably 40% or more, more preferably 45% or more, and even more preferably 50% or more. When it is less than 40%, it may not be possible to obtain desired mechanical properties when formed into a molded product. Also, the upper limit of the volume content ratio is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less. If it exceeds 80%, it may contain voids and may impair the mechanical properties.

[0036] The lower limit of the areal weight of the reinforcing fibers contained in the prepreg is 50 g / m 2The above is preferable, 100 g / m 2 The above is more preferable, 150 g / m 2 The above is even more preferable. 50 g / m 2 If it is less than this, voids where no reinforcing fibers exist may occur within the plane of the prepreg, which may become the starting point of fracture. On the other hand, as the upper limit of the areal weight of the reinforcing fibers contained in the prepreg, 1000 g / m 2 The following is preferable, 600 g / m 2 The following is more preferable, 400 g / m 2 The following is even more preferable. 1000 g / m 2 If it exceeds this, it may not be possible to uniformly transfer heat inside during molding, and there is a risk that the desired quality cannot be obtained. The measurement of the areal weight of the reinforcing fibers is carried out by cutting out a 10 cm square area from the sheet-like material of the reinforcing fibers, measuring its mass, and dividing by the area. The measurement is performed 10 times at different sites of the sheet-like material of the reinforcing fibers, and the average value is taken as the areal weight of the reinforcing fibers.

[0037] (2) Process for forming fitting portions and stepped portions on the skin Discontinuous fiber reinforced materials such as cut prepregs, long fiber pellets, and short fiber pellets are preferably used. When using long fiber pellets or short fiber pellets, they can be produced by injection molding or 3D printing molding with long fiber pellets or short fiber pellets at locations on the skin molded in step (1) that are to become fitting portions or stepped portions. Here, a cut prepreg is one with a cut on its surface (such a prepreg is referred to as a "cut prepreg"). The cut prepreg preferably has cuts regularly distributed over the entire in-plane area, and the reinforcing fibers contained in the prepreg are cut at the locations where the cuts exist. Such regularly distributed cuts can be provided, for example, by the method described in the specification of Patent No. 5272418.

[0038] According to the cut prepreg, openings and displacements are likely to occur at the locations where cuts are provided, and the stretchability of the prepreg in the direction of the reinforcing fibers is improved. Also, due to the flow during compression molding, the cut insertion location is opened and the fiber bundles of the reinforcing fibers are separated from each other, so that the prepreg exhibits flexibility and its fluidity is increased. By making the prepreg configured to be easily flowable or deformable in this way, the reinforcing fibers can reach the end portions, and the region where resin becomes excessive is reduced, enabling the press molding of a skin having a fitting portion excellent in mechanical properties and appearance. By using the cut prepreg, steps (1) and (2) can be performed simultaneously, and it is also possible to mold a skin with a fitting portion and a stepped portion in one step. From the viewpoint of fluidity, it is preferable that the cuts are made throughout the entire thickness direction of the prepreg.

[0039] (3) Forming process of the shear web It is convenient to perform the forming using a sheet-shaped fiber-reinforced composite material. In particular, as the sheet-shaped fiber-reinforced composite material, a thermosetting prepreg or a thermoplastic prepreg known as an intermediate base material in which resin is impregnated in the reinforcing fibers in advance can be preferably used. Also, it is possible to impregnate resin during the forming process for a fabric, a braiding base material, or an NCF (non-crimp fabric) that does not contain resin. As the forming method, autoclave molding, press molding, transfer molding, pultrusion molding, AFP (automated fiber placement), stamping molding, etc. can be applied in the same manner as in step (1).

[0040] (4) Bonding process between the skin and the shear web Using the upper skin, the lower skin, and the shear web formed in steps (1) to (3), the upper skin and the lower skin are bonded at the joint surface of the upper skin and the lower skin including the stepped portion, and the shear web is fitted and bonded to the fitting portion provided on the inner layer side surfaces of the upper skin and the lower skin. For the bonding, as described above, welding or adhesion can be applied. In particular, it is preferable to use an adhesive having foamability, and since the adhesive foams and cures by the heat during molding, it is possible to bond the fitting portion without gaps.

[0041] Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment at all, and any changes can be made within the scope that satisfies the requirements defined in the present invention.

Industrial Applicability

[0042] The hollow rotating wing according to the present invention is particularly suitable as a rotating wing for a UAM aircraft.

Explanation of Signs

[0043] 1 Hollow rotating wing 2a Tip of the hollow rotating wing 2b Root of the hollow rotating wing 3a Upper skin 3b Lower skin 4 Shear web 5a, 5b Step portions on the trailing edge side 6a, 6b Step portions on the leading edge side 7a, 7b Fitting portions 8a, 8b Hollow portions

Claims

1. An upper skin that mimics the upper surface of a wing formed of a fiber-reinforced composite material, a lower skin that mimics the lower surface of a wing formed of a fiber-reinforced composite material, and a shear web that exists between the upper skin and the lower skin and supports them. The upper skin and the lower skin have a fitting portion for fitting the shear web to the inner layer side surface thereof and a stepped portion that meshes when overlapped. A hollow rotating wing in which the shear web is fitted to the fitting portion.

2. The hollow rotating wing according to claim 1, wherein the dihedral angle of two adjacent planar portions of the stepped portion exceeds 90°.

3. The fitting portion has a foamed adhesive layer, and the shear web is adhered to the upper skin and the lower skin via the foamed adhesive layer, or the stepped portion has a foamed adhesive layer, and the upper skin and the lower skin are adhered via the foamed adhesive layer. The hollow rotating wing according to claim 1 or 2, characterized in that.

4. The hollow rotating wing according to claim 3, wherein the thickness of the foamed adhesive layer is 0.05 mm or more and 0.4 mm or less.

5. The reinforcing fibers contained in the fiber-reinforced composite material constituting the fitting portion or the stepped portion are discontinuous fibers. The hollow rotating wing according to claim 1 or 2, characterized in that.

6. The hollow rotating wing according to claim 5, wherein the fitting portion is formed of a fiber-reinforced composite material made of a thermosetting resin or a thermoplastic resin in which discontinuous reinforcing fibers are dispersed therein.

7. The hollow rotating wing according to claim 1 or 2, characterized in that the shear web has a bent portion in a top view thereof.

8. The volume content ratio of the reinforcing fibers contained in the skin and the volume content ratio of the reinforcing fibers contained in the shear web are both 10% or more greater than the volume content ratio of the reinforcing fibers contained in the fitting portion. The hollow rotating wing according to claim 1 or 2, characterized in that.

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