Blade

Abstract

To reduce the weight of a blade.SOLUTION: The blade includes a blade body and a lid member. The blade body has a recess and a first rib extending within the recess. The lid member includes a lid portion and a second rib. The lid is attached to the blade body so as to cover the recess. The second rib protrudes from the lid portion toward the bottom surface of the recessed portion. The first rib is joined to the lid portion. The second rib is joined to the bottom surface of the recess.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a blade. [Background technology]

[0002] A rotorcraft such as a drone has a motor, a hub, and multiple blades (Patent Document 1). Each blade is attached to the motor via the hub. The motor rotates the hub and each blade. The blades are formed, for example, by injection molding. As a result, the blades are solid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-104369 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for lighter blades for reasons such as reducing power consumption, and an object of the present invention is to reduce the weight of the blades. [Means for solving the problem]

[0005] The blade according to the first aspect comprises a blade body and a cover member. The blade body has a recess and a first rib extending within the recess. The cover member has a cover portion and a second rib. The cover portion is attached to the blade body so as to cover the recess. The second rib protrudes from the cover portion toward the bottom surface of the recess. The first rib is joined to the cover portion. The second rib is joined to the bottom surface of the recess.

[0006] According to this configuration, a recess is provided in the blade body and the recess is covered with the cover member, thereby forming a space inside the blade. This allows the blade to be lighter. Furthermore, to ensure strength, a first rib formed on the blade body and a second rib formed on the cover member extend within the recess. The first rib is joined to the cover member, and the second rib is joined to the blade body.

[0007] The blade according to the second aspect is configured as follows in the blade according to the first aspect. The blade body has a third rib extending to intersect with the first and second ribs.

[0008] A blade according to a third aspect is the blade according to the second aspect, configured as follows: The third rib has a slit, and the second rib intersects with the third rib via the slit.

[0009] A blade according to a fourth aspect is the blade according to the second or third aspect, configured as follows: The first rib is thicker than the third rib.

[0010] A blade according to a fifth aspect is the blade according to any one of the first to fourth aspects, configured as follows: The first rib is thinner at its tip end than at its base end.

[0011] A blade according to a sixth aspect is the blade according to any one of the first to fifth aspects, configured as follows: The first rib and the second rib extend linearly.

[0012] A blade according to a seventh aspect is the blade according to any one of the first to sixth aspects, configured as follows: The thickness of the second rib is greater than the thickness of the lid portion.

[0013] The blade according to an eighth aspect is the blade according to any one of the first to seventh aspects, configured as follows: both ends of the first rib are connected to the side surfaces that define the recess, and at least one end of the both ends of the second rib is disposed at a distance from the side surfaces that define the recess.

[0014] A blade according to a ninth aspect is the blade according to any one of the first to eighth aspects, configured as follows: The blade body has a pair of first ribs. A second rib is disposed between the pair of first ribs. The second ribs are disposed so that the distance between one of the first ribs and the second rib is different from the distance between the other of the first ribs and the second rib. [Effects of the Invention]

[0015] According to the present invention, the blade can be made lighter. [Brief explanation of the drawings]

[0016] [Figure 1] Plan view of a rotorcraft. [Figure 2] Bottom view of the blade. [Figure 3] Cross-sectional view of line III-III in Figure 2. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 10 is a cross-sectional view of a blade according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0017] The blade according to this embodiment will be described below with reference to the drawings. In the following description, the axial direction refers to the direction in which the rotation axis of the blade extends. The circumferential direction refers to the circumferential direction of a circle centered on the rotation axis, and the radial direction refers to the radial direction of a circle centered on the rotation axis.

[0018] <Rotorcraft> As shown in Fig. 1, the rotary-wing aircraft 100 has a plurality of electric motors 11 and a plurality of propellers 12. In detail, the rotary-wing aircraft 100 has a main body 101, a plurality of arms 102, and a plurality of rotors 103. Each rotor 103 has an electric motor 11 and a propeller 12. In this embodiment, the rotary-wing aircraft 100 has four rotors 103. That is, in this embodiment, the rotary-wing aircraft 100 is a multicopter drone.

[0019] The main body 101 has a battery (not shown), a control unit (not shown), etc. The arms 102 extend radially from the main body 101. The rotors 103 are attached to the tips of the arms 102.

[0020] The electric motors 11 are configured to rotate the propellers 12. The rotation direction differs depending on the electric motor 11. For example, the rotation direction of the electric motors 11 in the rotors 103 at the top right and bottom left of FIG. 1 is counterclockwise, and the rotation direction of the electric motors 11 in the rotors 103 at the top left and bottom right of FIG. 1 is clockwise.

[0021] The propeller 12 has a pair of blades 2 and a hub 3. Each blade 2 is attached to the electric motor 11 via the hub 3. Alternatively, each blade 2 may be attached to the electric motor 11 directly.

[0022] <Blade> FIG. 2 is a bottom view of the blade 2, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. As shown in FIGS. 2 and 3, the blade 2 has a blade body 4 and a cover member 5. The blade 2 extends in the radial direction. Specifically, the blade 2 extends radially outward from the center. The center is the center of rotation of the blade 2. In FIG. 2, the blade 2 rotates clockwise around the rotation axis O. The direction in which the blade body 4 and the cover member 5 extend is referred to as the longitudinal direction, and the direction perpendicular to the longitudinal direction is referred to as the lateral direction. In this embodiment, the longitudinal direction is along the radial direction, and the lateral direction is roughly along the circumferential direction.

[0023] <Blade body> FIG. 4 is a bottom view of the blade body 4. The two-dot chain line in FIG. 4 indicates the surface to which each second rib 52 of the cover member 5 is joined when the cover member 5 is attached to the blade body 4. As shown in FIG. 4, the blade body 4 has a recess 41, a plurality of first ribs 42, and a plurality of third ribs 43. The blade body 4 can be formed by, for example, injection molding. The blade body 4 can be formed from, for example, resin. Specifically, the blade body 4 can be formed from, for example, CFRTP (carbon fiber reinforced thermoplastic resin).

[0024] The recess 41 is formed in the bottom surface of the blade body 4. The recess 41 is recessed toward the top surface of the blade body 4. In other words, the recess 41 opens downward. The outer edge of the recess 41 extends along the outer edge of the blade body 4. The recess 41 extends in the longitudinal direction.

[0025] Each first rib 42 is formed on the bottom surface of the recess 41. That is, each first rib 42 protrudes from the bottom surface of the recess 41 toward the lid portion 51, which will be described later. Each first rib 42 extends within the recess 41. More specifically, each first rib 42 extends along the longitudinal direction within the recess 41. Each first rib 42 extends linearly. Each first rib 42 is arranged at intervals from each other in the lateral direction. Both ends of each first rib 42 are connected to the side surfaces that define the recess 41.

[0026] Each third rib 43 is formed on the bottom surface of the recess 41. That is, each third rib 43 protrudes from the bottom surface of the recess 41 toward the lid portion 51, which will be described later. Each third rib 43 extends in the short direction within the recess 41. That is, each third rib 43 extends so as to intersect with each first rib 42. Each third rib 43 extends so as to be substantially perpendicular to each first rib 42. Furthermore, each third rib 43 also extends so as to intersect with a second rib 52, which will be described later. Each third rib 43 is shorter than each first rib 42.

[0027] Each third rib 43 has a plurality of slits 431. Each slit 431 extends from the tip surface of the third rib 43 to the bottom surface of the recess 41. That is, each slit 431 divides each third rib 43. The third rib 43 is thinner than the first rib 42. Note that the thickness of the first rib 42 refers to the dimension of the first rib 42 in the short direction, and the thickness of the third rib 43 refers to the dimension of the third rib 43 in the long direction.

[0028] The blade body 4 has a joint surface 44. The joint surface 44 extends along the outer edge of the recess 41 so as to surround the recess 41. The joint surface 44 faces the cover member 5. The joint surface 44 is recessed by one step from the other surfaces of the blade body 4. In detail, the joint surface 44 is recessed from the other surfaces by an amount equal to the thickness of a cover member 51, which will be described later.

[0029] <Cover parts> Fig. 5 is a plan view of the cover member 5. The two-dot chain lines in Fig. 5 indicate the surfaces to which the first ribs 42, the third ribs 43, and the joining surface 44 of the blade body 4 are joined when the cover member 5 is attached to the blade body 4.

[0030] As shown in FIGS. 3 and 5, the cover member 5 has a cover portion 51 and a plurality of second ribs 52. The cover portion 51 and each of the second ribs 52 are integrally formed from a single member. The cover member 5 can be formed, for example, by injection molding. The cover member 5 can be formed, for example, from a resin. Specifically, the cover member 5 can be formed, for example, from CFRTP (carbon fiber reinforced thermoplastic resin). The cover member 5 can be made of the same material as the blade body 4. The cover member 5 is attached to the blade body 4. Specifically, the cover member 5 is attached to the bottom side of the blade body 4.

[0031] The lid portion 51 is flat and extends in the longitudinal direction. The lid portion 51 is attached to the blade body 4 so as to cover the recess 41 of the blade body 4. For example, the outer peripheral edge of the lid portion 51 is joined to the joining surface 44 of the blade body 4. The lid portion 51 is attached so as to be flush with the surface of the blade body 4. The first ribs 42 and the third ribs 43 are joined to the lid portion 51. Examples of methods for joining the first ribs 42, the third ribs 43, and the joining surface 44 to the lid portion 51 include bonding with an adhesive, ultrasonic welding, and heat welding.

[0032] Each second rib 52 is formed on the lid portion 51. That is, each second rib 52 protrudes from the lid portion 51 toward the blade body 4. More specifically, each second rib 52 protrudes from the lid portion 51 toward the bottom surface of the recess 41. The second rib 52 is joined to the bottom surface of the recess 41. Methods for joining each second rib 52 to the bottom surface of the recess 41 include bonding with an adhesive, ultrasonic welding, and thermal welding. The thickness of each second rib 52 is thicker than the thickness of the lid portion 51. The thickness of the second rib 52 refers to the dimension of the second rib 52 in the short direction.

[0033] Each second rib 52 extends along the longitudinal direction. Each second rib 52 extends within the recess 41 of the blade body 4. Each second rib 52 extends along the same direction as each first rib 42. Each second rib 52 extends linearly. Of both end portions of each second rib 52, one end abuts against a side surface that defines the recess 41, and the other end is disposed at a distance from the side surface that defines the recess 41.

[0034] Each second rib 52 is disposed at a distance from each first rib 42 in the short-side direction. Each first rib 42 and each second rib 52 are disposed alternately in the short-side direction. Of the multiple second ribs 52, the second rib 52 disposed between a pair of first ribs 42 has a different distance from one first rib 42 than from the other first rib 42. Specifically, the second rib 52 is closer to the longer first rib 42 of the pair of first ribs 42 than the shorter first rib 42.

[0035] Each second rib 52 intersects with each third rib 43. More specifically, each second rib 52 extends through a slit 431 formed in each third rib 43. The thickness of the second rib 52 is approximately the same as the width of the slit 431. The width of the slit 431 refers to the dimension of the slit 431 in the short direction.

[0036] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention. Note that the following modifications can basically be applied simultaneously.

[0037] (a) As shown in Fig. 6, each of the first ribs 42 may be configured so that the tip portion is thinner than the base portion. In particular, the thickness of each of the first ribs 42 may be configured so that it gradually decreases from the base portion toward the tip portion.

[0038] Similarly, each of the second ribs 52 and each of the third ribs 43 may be configured to be thinner at the tip end than at the base end. In particular, the thickness of each of the second ribs 52 and each of the third ribs 43 may be configured to gradually decrease from the base end toward the tip end.

[0039] (b) In the above embodiment, the recess 41 is formed on the bottom surface of the blade body 4, but it may be formed on the top surface of the blade body 4. In this case, the cover member 5 is attached to the top surface side of the blade body 4.

[0040] (c) In the above embodiment, the first ribs 42 and the second ribs 52 are not spaced apart at equal intervals, but the first ribs 42 and the second ribs 52 may be spaced apart at equal intervals.

[0041] (d) In the above embodiment, the blade body 4 has the third ribs 43, but the cover member 5 may have the third ribs 43. In this case, the third ribs 43 are joined to the bottom surface of the recess 41. Furthermore, the first ribs 42 pass through the slits 431 of the third ribs 43. [Explanation of symbols]

[0042] 2: Blade 4: Blade body 41: Recess 42: First rib 43: Third Rib 431: Slit 5: Lid member 51: Lid part 52: Second rib 101: Main body

Claims

1. a blade body having a recess and a first rib extending within the recess; a cover member including a cover portion attached to the blade body so as to cover the recessed portion, and a second rib protruding from the cover portion toward a bottom surface of the recessed portion; Equipped with the first rib is joined to the lid portion, The second rib is joined to a bottom surface of the recess. blade.

2. The blade body has a third rib extending to intersect with the first rib and the second rib. The blade of claim 1 .

3. the third rib has a slit, The second rib intersects with the third rib through the slit. The blade of claim 2.

4. The first rib is thicker than the third rib. The blade of claim 2.

5. The first rib is thinner at its tip than at its base. The blade of claim 1 .

6. The first rib and the second rib extend linearly. The blade of claim 1 .

7. The thickness of the second rib is greater than the thickness of the lid portion. The blade of claim 1 .

8. Both ends of the first rib are connected to the side surfaces that define the recess, At least one end of the second rib is spaced apart from a side surface that defines the recess. The blade of claim 1 .

9. The blade body has a pair of the first ribs, The second rib is disposed between the pair of first ribs, and is disposed such that a distance between one of the first ribs and the second rib is different from a distance between the other of the first ribs and the second rib. The blade of claim 1 .

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