Foldable blade assembly

Abstract

A foldable blade assembly can include a first blade, an electric motor configured to rotate the first blade, a second blade having a center of rotation that coincides with a center of rotation of the first blade, and an actuator configured to move the second blade upward or downward to selectively couple the second blade to the first blade so that the second blade rotates with the first blade or to release the coupling between the second blade and the first blade.

Description

Technical Field

[0001] The present invention relates to a foldable blade assembly, and more specifically, to a foldable blade assembly having the function of automatically folding the blades to minimize drag caused by blades not being used in cruise mode in urban air vehicles having a vertical motion mode and a driving mode including a cruise mode. Background Technology

[0002] Recently, there has been active development in the technology of drones and urban air vehicles. However, in traditionally developed drones or urban air vehicles, the blades are folded to minimize volume during loading or movement, and this folding can be done manually once the drone or urban air vehicle is in its flight-completed state. Therefore, it is impossible to minimize wind resistance during flight.

[0003] Therefore, in cruise mode, which is the most common operating mode for drones or urban air vehicles, a technology is needed to minimize wind resistance caused by the blades.

[0004] The information included in this background section of the invention is intended only to enhance the understanding of the general background of the invention and should not be construed as an admission or in any way implying that this information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] Various aspects of the present invention aim to provide a foldable blade assembly with the function of automatically folding blades to minimize drag caused by blades not used in cruise mode in urban air vehicles having a vertical motion mode and a driving mode including a cruise mode.

[0006] According to one aspect, a foldable blade assembly is provided, comprising: a first blade; a motor configured to rotate the first blade; a second blade having a rotation center coinciding with the rotation center of the first blade; and an actuator configured to move the second blade up or down to selectively couple the second blade to the first blade such that the second blade and the first blade rotate together, or to release the coupling between the second blade and the first blade.

[0007] The foldable blade assembly may further include: a first shaft fixedly connected to and coupled to the first blade to a motor; a second shaft fixedly connected to the second blade and coupled to or separated from the inside of the first shaft; and a third shaft connected to an actuator and configured to move the second shaft upward or downward by moving upward or downward as the actuator is driven.

[0008] A hollow portion can be formed in the motor, and a third shaft can pass through the hollow portion of the motor, can be inserted into the first shaft, and can move up or down as the actuator is driven to move the second shaft up or down, so that the second blade can be coupled to the first blade to rotate together with it, or the coupling between the second blade and the first blade can be released.

[0009] A through hole can be formed in the central portion of the first shaft, and the inner surface of the through hole can be formed to be inclined downward so that the diameter of the inner surface of the through hole narrows toward the motor. The second shaft can be formed to correspond to the shape of the through hole of the first shaft so as to be inserted along the inclined surface formed on the inner surface of the through hole of the first shaft.

[0010] Concave or convex serrations can be formed on the inclined inner circumferential surface of the through hole of the first shaft, and convex or concave serrations can be formed on the inclined outer circumferential surface of the second shaft.

[0011] The central part of the rotation axis of the first blade can coincide with the central part of the rotation axis of the second blade.

[0012] In the vertical motion mode, the first and second axes can be serratedly coupled, so that power from the motor can be transmitted to the first and second blades through the first and second axes, and thus the first and second blades can rotate.

[0013] In the first blade folding mode, the actuator can move the third axis upward to move the second blade upward by a predetermined distance, thereby releasing the serrated coupling between the second axis and the first axis.

[0014] In the second blade folding mode, the motor can rotate the first blade to be positioned below the second blade.

[0015] In the third blade folding mode, the actuator can move the third axis downward to move the second blade downward, thereby stacking the second blade on top of the first blade located below the second blade.

[0016] The first fixing groove can be set on the upper surface of the first shaft, and the fixing protrusion can be set on the lower surface of the second blade at a position corresponding to the position where the first fixing groove is set. In the vertical movement mode, the fixing protrusion of the second blade can be coupled to the first fixing groove.

[0017] The second fixing groove can be set on the upper surface of the first blade, and the fixing protrusion can be set on the lower surface of the second blade at a position corresponding to the position where the second fixing groove is set. In the third blade folding mode, the fixing protrusion of the second blade can be coupled to the second fixing groove.

[0018] The second shaft can be connected to the third shaft via a bearing assembly.

[0019] The methods and apparatus of the present invention have other features and advantages, which will be apparent from or will be set forth in more detail in the accompanying drawings and the following detailed description, which together serve to explain certain principles of the invention. Attached Figure Description

[0020] Figure 1 This is an exemplary perspective view showing a foldable blade assembly according to various exemplary embodiments of the present invention;

[0021] Figure 2 An exploded perspective view of a foldable blade assembly according to various exemplary embodiments of the present invention is shown exemplarily.

[0022] Figure 3 This is an exemplary cross-sectional view of a foldable blade assembly according to various exemplary embodiments of the present invention;

[0023] Figure 4 This is an illustration showing the first axis of a foldable blade assembly according to various exemplary embodiments of the present invention;

[0024] Figure 5 This is an illustration showing a second shaft of a second blade coupled to a foldable blade assembly according to various exemplary embodiments of the present invention;

[0025] Figure 6 This is an illustration showing a second fixing groove formed in a first blade of a foldable blade assembly according to various exemplary embodiments of the present invention;

[0026] Figure 7 and Figure 8 This is an illustration used to describe the state of the vertical motion mode of a foldable blade assembly according to various exemplary embodiments of the present invention;

[0027] Figure 9 and Figure 10 This is an illustration used to depict the upward movement of a second blade in a first blade folding mode of a foldable blade assembly according to various exemplary embodiments of the present invention;

[0028] Figure 11 and Figure 12 This is an illustration depicting a first blade rotating 180 degrees in a second blade folding mode in a foldable blade assembly according to various exemplary embodiments of the present invention; and

[0029] Figure 13 and Figure 14This is an illustration used to describe, in a third blade folding mode of a foldable blade assembly according to various exemplary embodiments of the present invention, a second blade moves downward to overlap the first blade.

[0030] It is understood that the accompanying drawings need not be drawn to scale, and present slightly simplified representations of various features illustrating the basic principles of the invention. Specific design features of the invention as included herein (including, for example, specific dimensions, orientations, positions, and shapes) will be determined in part by the particular intended application and environment of use.

[0031] In the accompanying drawings, in several figures, reference numerals denote the same or equivalent parts of the invention. Detailed Implementation

[0032] Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments thereof, it will be understood that this description is not intended to limit the invention to those exemplary embodiments. On the other hand, the invention is intended to cover not only the exemplary embodiments thereof, but also various alternatives, modifications, equivalents and other embodiments that may be included within the spirit and scope of the invention as defined by the appended claims.

[0033] In the following, various exemplary embodiments of the foldable blade assembly according to the present invention will be described in detail with reference to the accompanying drawings.

[0034] Figure 1 This is an exemplary perspective view showing a foldable blade assembly according to various exemplary embodiments of the present invention. Figure 2 An exploded perspective view of a foldable blade assembly according to various exemplary embodiments of the present invention is shown, and Figure 3 This is an exemplary cross-sectional view illustrating a foldable blade assembly according to various exemplary embodiments of the present invention. Furthermore, Figure 4 This is an illustration showing the first axis of a foldable blade assembly according to various exemplary embodiments of the present invention. Figure 5 This is an illustration showing the second axis of a second blade coupled to a foldable blade assembly according to various exemplary embodiments of the present invention. Figure 6 This is an illustration showing a second fixing groove formed in the first blade of a foldable blade assembly according to various exemplary embodiments of the present invention. Figure 7 and Figure 8 This is an illustration used to depict the states of a vertical motion mode of a foldable blade assembly according to various exemplary embodiments of the present invention. Figure 9 and Figure 10 This is an illustration depicting the upward movement of a second blade in a first blade folding mode of a foldable blade assembly according to various exemplary embodiments of the present invention. Figure 11 and Figure 12 This is an illustration used to depict a first blade rotating 180 degrees in a second blade folding mode in a foldable blade assembly according to various exemplary embodiments of the present invention, and Figure 13 and Figure 14 This is an illustration used to describe, in a third blade folding mode of a foldable blade assembly according to various exemplary embodiments of the present invention, a second blade moves downward to overlap the first blade.

[0035] refer to Figure 1 , Figure 2 and Figure 3 According to various exemplary embodiments of the present invention, a foldable blade assembly may include a first blade 200, a motor 100, a second blade 300, an actuator 400, a first shaft 500, a second shaft 600, and a third shaft 700.

[0036] The motor 100 is configured to transmit power to the first blade 200 to cause the first blade 200 to rotate. Furthermore, the motor 100 is configured to transmit power to the first blade 200 and the second blade 300 to cause both blades to rotate. When the first blade 200 and the second blade 300 are coupled according to the drive of the actuator 400, which will be described below, the power of the motor 100 can be transmitted to both blades to cause them to rotate together. When the coupling between the first blade 200 and the second blade 300 is released, the power of the motor 100 can be transmitted only to the first blade 200 to cause only the first blade 200 to rotate.

[0037] The first blade 200 can be rotated by coupling the first shaft 500, as described below, to the motor 100 and by receiving power from the motor 100.

[0038] The rotation center of the second blade 300 can coincide with the rotation center of the first blade 200. When the second blade 300 is coupled to the first blade 200, the second blade 300 can rotate together with the first blade 200 due to the power transmitted from the motor 100.

[0039] The actuator 400 moves the second blade 300 up or down, such that the second blade 300 can be coupled to the first blade 200 and rotate together with it, or the coupling between the second blade 300 and the first blade 200 can be released.

[0040] The first shaft 500 can be connected to the first blade 200, and the first blade 200 can be coupled to the motor 100. The first shaft 500 can transmit power from the motor 100 to the first blade 200 to make the first blade 200 rotate.

[0041] The second shaft 600 can be connected to the second blade 300 and coupled to the inside of the first shaft 500 or separated from the inside of the first shaft. When the second shaft 600 is coupled to the inside of the first shaft 500, the second shaft 600 can transmit power from the motor 100 to the second blade 300 so that the second blade 300 rotates together with the first blade 200.

[0042] The third axis 700 is connected to the actuator 400. When the actuator 400 is driven, the third axis 700 can move up or down to move the second axis 600 up or down.

[0043] refer to Figure 1 and Figure 2 A hollow portion may be formed in the motor 100. Furthermore, the third shaft 700 may pass through the hollow portion of the motor 100, be inserted into the first shaft 500, and be able to move up or down when the actuator 400 is driven to move the second shaft 600 up or down, thereby coupling the second blade 300 to the first blade 200 to rotate together with it, or releasing the coupling between the second blade 300 and the first blade 200.

[0044] In other words, while moving the third shaft 700 upward to move the second blade 300 upward, the actuator 400 releases the coupling between the first shaft 500 and the second shaft 600, thereby releasing the coupling between the first blade 200 and the second blade 300. While moving the third shaft 700 downward to move the second blade 300 downward, the actuator 400 couples the first shaft 500 to the second shaft 600, thereby coupling the first blade 200 to the second blade 300.

[0045] At the same time, refer to Figure 4 A through hole can be formed in the central portion of the first shaft 500, and the inner surface of the through hole can be formed to be inclined downward so that the diameter of the inner surface of the through hole narrows toward the motor 100.

[0046] refer to Figure 5 The second shaft 600 can be formed in a shape corresponding to the shape of the through hole in the first shaft 500, so as to be inserted along an inclined surface formed on the inner surface of the through hole formed in the first shaft 500.

[0047] refer to Figure 4 and Figure 5 A concave serration 520 or a convex serration 520 can be formed on the inclined inner peripheral surface of the through hole of the first shaft 500, and a convex serration 610 or a concave serration 610 can be formed on the inclined outer peripheral surface of the second shaft 600.

[0048] According to various exemplary embodiments of the present invention, when the concave sawtooth 520 is formed on the inclined inner peripheral surface of the through hole of the first shaft 500, the convex sawtooth 610 may be formed on the inclined outer peripheral surface of the second shaft 600.

[0049] Alternatively, when the convex sawtooth 520 is formed on the inclined inner peripheral surface of the through hole of the first shaft 500, the concave sawtooth 610 may be formed on the inclined outer peripheral surface of the second shaft 600.

[0050] As described above, in the foldable blade assembly according to various exemplary embodiments of the present invention, concave or convex serrations 520 are formed on the inclined inner peripheral surface of the through hole of the first shaft 500, and convex or concave serrations 610 are formed on the inclined outer peripheral surface of the second shaft 600, such that in the vertical movement mode, the second shaft 600 can be easily coupled along the inclined inner peripheral surface of the first shaft 500, and in the first blade folding mode, when the second shaft 600 moves upward, the second shaft 600 moves upward without interfering with the first shaft 500, such that the serration coupling between the second shaft 600 and the first shaft 500 can be easily released.

[0051] Meanwhile, according to another exemplary embodiment of the present invention, a protrusion may be formed on the inclined inner peripheral surface of the through hole of the first shaft 500, and a groove to which the protrusion can be coupled may be formed on the inclined outer peripheral surface of the second shaft 600. However, the shapes formed on the inclined inner peripheral surface of the through hole of the first shaft 500 and the inclined outer peripheral surface of the second shaft 600 are not limited to the above-mentioned concave / convex serrations and protrusions, and various shapes different from these shapes may be applied to the inclined inner peripheral surface of the first shaft 500 and the inclined outer peripheral surface of the second shaft 600, as long as they can easily couple the first shaft 500 to the second shaft 600 or easily separate the first shaft 500 from the second shaft 600.

[0052] In the foldable blade assembly according to various exemplary embodiments of the present invention, the central portion of the rotation axis of the first shaft 500 may coincide with the central portion of the rotation axis of the second shaft 600. As described above, since the rotation axis of the first shaft 500 coincides with the rotation axis of the second shaft 600, when the first shaft 500 and the second shaft 600 are coupled and therefore the first blade 200 and the second blade 300 rotate together, the first blade 200 and the second blade 300 can rotate stably without wobbling.

[0053] At the same time, refer to Figure 4 , Figure 5 and Figure 6 The first fixing groove 510 can be set on the upper surface of the first shaft 500, and the fixing protrusion 310 can be set on the lower surface of the second blade 300 at a position corresponding to the position where the first fixing groove 510 is set.

[0054] In an exemplary embodiment of the present invention, the second blade 300 includes a locking protrusion 330, and the first blade 200 includes a locking groove 230, such that in a vertical movement mode, the locking protrusion 330 of the second blade 300 is coupled to the locking groove 230 of the first blade 200. In an exemplary embodiment of the present invention, the locking protrusion 330 of the second blade 300 is formed to extend along the longitudinal axis of the second blade 300, and the locking groove 230 of the first blade 200 is formed to be recessed along the longitudinal axis of the first blade 200.

[0055] However, in an exemplary embodiment of the present invention, the first blade 200 may include a locking protrusion, and the second blade 300 may include a locking groove, such that in a vertical movement mode, the locking groove of the second blade 300 is coupled to the locking protrusion of the first blade 200. In an exemplary embodiment of the present invention, the locking protrusion of the first blade 200 is formed to extend along the longitudinal axis of the first blade 200, and the locking groove of the second blade 300 is formed to be recessed along the longitudinal axis of the second blade 300.

[0056] As described above, in the foldable blade assembly according to various exemplary embodiments of the present invention, since the first fixing groove 510 is provided on the upper surface of the first shaft 500 and the fixing protrusion 310 is provided on the lower surface of the second blade 300 at a position corresponding to the position where the first fixing groove 510 is provided, in the vertical movement mode, the fixing protrusion 310 of the second blade 300 is coupled to the first fixing groove 510, so that the physical movement of the second blade 300 can be restricted.

[0057] Furthermore, since the second fixing groove 210 is disposed on the upper surface of the first blade 200 and the fixing protrusion 310 is disposed on the lower surface of the second blade 300 at a position corresponding to the position where the second fixing groove 210 is disposed, in the third blade folding mode, the fixing protrusion 310 of the second blade 300 is coupled to the second fixing groove 210, thereby restricting the physical movement of the second blade 300.

[0058] Meanwhile, the second shaft 600 can be connected to the third shaft 700 via the bearing assembly 800. That is, the bearing assembly is disposed between the second shaft 600 and the third shaft 700, so that the third shaft 700, which does not rotate when the second shaft 600 rotates, and the actuator 400 can be connected.

[0059] In the following text, reference will be made to Figures 7 to 14 The blade folding modes are described in detail, including the vertical movement mode, the first blade folding mode, the second blade folding mode, and the third blade folding mode.

[0060] According to various exemplary embodiments of the present invention, the vertical motion mode can be a mode in which the first blade 200 and the second blade 300 receive power from the motor 100 to rotate and then move upward and lift. (See reference) Figure 7 and Figure 8 In the vertical motion mode, since the first shaft 500 and the second shaft 600 are serrated, power from the motor 100 is transmitted to the first blade 200 and the second blade 300 via the first shaft 500 and the second shaft 600, and thus the first blade 200 and the second blade 300 rotate, allowing the urban air vehicle, including the foldable blade assembly, to be lifted. Here, the first blade 200 can receive power from the motor 100 by being coupled to the first shaft 500, and the concave serration 520 of the first shaft 500 is coupled to the convex serration 610 of the second shaft 600, so that the second blade 300 can receive power transmitted from the motor 100 via the first shaft 500 and the second shaft 600.

[0061] Simultaneously, in the cruise mode following the vertical motion mode, since the first blade 200 and the second blade 300 do not need to rotate, it is necessary to minimize the wind resistance generated by the blades in the cruise mode by folding the first blade 200 and the second blade 300. Here, the blade folding modes include the first blade folding mode, the second blade folding mode, and the third blade folding mode, and these modes will refer to... Figures 9 to 14 To describe in more detail.

[0062] refer to Figure 9 and Figure 10 In the first blade folding mode, actuator 400 moves third shaft 700 upward to move second blade 300 upward by a predetermined distance, thereby releasing the serrated coupling between second shaft 600 and first shaft 500. In this case, the predetermined distance by which actuator 400 moves second blade 300 upward can be a distance that does not interfere with second blade 300 when first blade 200 rotates in the second blade folding mode.

[0063] refer to Figure 11 and Figure 12 In the first blade folding mode, the motor 100 can rotate the first blade 200 to a position below the second blade 300. Various exemplary embodiments of the present invention are available, such as... Figure 9 As shown, when the first blade 200 and the second blade 300 are horizontally positioned in opposite directions, in the first blade folding mode, the motor 100 can rotate the first blade 200 180 degrees to position it below the second blade 300.

[0064] refer to Figure 13 and Figure 14 In the second blade folding mode, the actuator 400 moves the third shaft 700 downward to move the second blade 300 downward so that the second blade 300 can be stacked on the first blade 200 located below the second blade 300.

[0065] At the same time, when the cruise mode is completed, the above process can be reversed to restore the first blade 200 and the second blade 300, which are stacked on top of each other, to their initial state, so that the first blade 200 and the second blade 300 can rotate due to the power transmitted from the motor 100.

[0066] Meanwhile, although not shown in detail in the accompanying drawings, the foldable blade assembly may also include a controller configured to control the drive of the motor 100 and the actuator 400. According to various exemplary embodiments of the invention, the controller may be implemented as a processor chip or the like. The controller controls the drive of the motor 100 and the actuator 400 according to a vertical motion mode, a first blade folding mode, a second blade folding mode, and a third blade folding mode, such that in the vertical motion mode, the controller allows the blades 200 and 300 to rotate together due to the power transmitted from the motor 100, and in the cruise mode, the controller can stack the second blade 300 and the first blade 200 through the first blade folding mode, the second blade folding mode, and the third blade folding mode, thereby minimizing wind resistance generated by the first blade 200 and the second blade 300.

[0067] Simultaneously, the aforementioned foldable blade assembly can be included in urban air vehicles. In other words, as described above, in the vertical motion mode of the urban air vehicle, the first blade 200 and the second blade 300 rotate due to the power transmitted from the motor 100, allowing the urban air vehicle to be lifted. Furthermore, when the urban air vehicle is in cruise mode, the second blade 300 and the first blade 200 are stacked through a first blade folding mode, a second blade folding mode, and a third blade folding mode, thereby minimizing wind resistance generated by the first blade 200 and the second blade 300.

[0068] According to various aspects of the invention, the actuator and the motor are controlled, and thus the first and second blades can be folded, such that in the cruise mode following the vertical motion mode, the first and second blades can be stacked, and thus in the cruise mode, the wind resistance generated by the first and second blades can be minimized.

[0069] Furthermore, since the fixing protrusion is provided on the lower surface of the second blade and the fixing groove is provided on the upper surface of the first shaft and the upper surface of the first blade, in the vertical movement mode and the third blade folding mode, the fixing protrusion is coupled to the fixing groove provided on the upper surface of the first shaft or the upper surface of the first blade, so that the position of the second blade can be physically restricted.

[0070] Furthermore, since the first and second axes are formed in an inclined shape and are coupled in a sawtooth pattern, coupling between the first and second axes or separation between the first and second axes can be facilitated in vertical motion mode or blade folding mode.

[0071] For ease of interpretation and precise definition of the appended claims, the terms “upper,” “lower,” “inner,” “outer,” “up,” “lower,” “upward,” “downward,” “front,” “back,” “rear,” “inner,” “external,” “inward,” “outward,” “inner,” “external,” “inner,” “outer,” “inner,” “outer,” “forward,” and “backward” are used to describe these features of the exemplary embodiments with reference to the positions of the features shown in the accompanying drawings. It will also be understood that the term “connection” or its derivatives refer to both direct and indirect connections.

[0072] For purposes of illustration and description, the above description of specific exemplary embodiments of the invention has been given. It is not intended to be exhaustive, nor to limit the invention to the precise forms disclosed, and it will be apparent that many modifications and variations are possible in accordance with the foregoing teachings. Exemplary embodiments were chosen and described to explain certain principles of the invention and its practical application, so that those skilled in the art can make and utilize various exemplary embodiments of the invention and their various alternatives and modifications. The aim is that the scope of the invention be defined by the appended claims and their equivalents.

Claims

1. A foldable blade assembly, comprising: First blade; The motor is configured to rotate the first blade; The second blade has a rotation center that coincides with the rotation center of the first blade. as well as An actuator is configured to move the second blade up or down to selectively couple the second blade to the first blade such that the second blade and the first blade rotate together, or to release the coupling between the second blade and the first blade. Also includes: A first shaft is fixedly connected to the first blade and couples the first blade to the motor; A second shaft, fixedly connected to the second blade and configured to be coupled to the inside of the first shaft or separated from the inside of the first shaft; and A third axis is connected to the actuator and configured to move the second axis upward or downward by moving it upward or downward as the actuator is driven.

2. The foldable blade assembly according to claim 1, in, A hollow portion is formed in the motor; and The third shaft is aligned to pass through the hollow portion of the motor, slidably inserted into the first shaft, and configured to move upward or downward as the actuator is driven, causing the second shaft to move upward or downward, such that the second blade is coupled to the first blade to rotate together with the first blade, or to release the coupling between the second blade and the first blade.

3. The foldable blade assembly according to claim 1, in, A through hole is formed in the central portion of the first shaft, and the inner surface of the through hole is formed to slope downward so that the diameter of the inner surface of the through hole narrows toward the central axis of the first shaft. and The second shaft is formed in a shape corresponding to the shape of the through hole of the first shaft, so as to be inserted along an inclined surface formed on the inner surface of the through hole of the first shaft.

4. The foldable blade assembly according to claim 3, in, One of a concave sawtooth or a convex sawtooth is formed on the inclined inner circumferential surface of the through hole of the first shaft; and The second shaft has either a convex sawtooth or a concave sawtooth formed on its inclined outer peripheral surface.

5. The foldable blade assembly according to claim 1, wherein, The central portion of the rotation axis of the first blade coincides with the central portion of the rotation axis of the second blade.

6. The foldable blade assembly according to claim 4, wherein, In the vertical motion mode, the first and second axes are serrated, such that power from the motor is transmitted through the first and second axes to the first and second blades, thereby causing the first and second blades to rotate.

7. The foldable blade assembly according to claim 4, wherein, In the first blade folding mode, the actuator moves the third axis upward so that the second blade moves upward from the first blade by a predetermined distance, thereby releasing the serrated coupling between the second axis and the first axis.

8. The foldable blade assembly according to claim 7, wherein, In the second blade folding mode, the motor rotates the first blade to a position below the second blade.

9. The foldable blade assembly according to claim 8, wherein, In the third blade folding mode, the actuator moves the third axis downward to move the second blade downward, thereby stacking the second blade on top of the first blade located below the second blade.

10. The foldable blade assembly according to claim 1, in, The first fixing groove is disposed on the upper surface of the first shaft; The fixing protrusion is disposed on the lower surface of the second blade at a position corresponding to the position where the first fixing groove is disposed; and In the vertical motion mode, the fixed protrusion of the second blade is coupled to the first fixed groove.

11. The foldable blade assembly according to claim 1, in, The second fixing groove is provided on the upper surface of the first blade; The fixing protrusion is disposed on the lower surface of the second blade at a position corresponding to the position where the second fixing groove is disposed; and In the third blade folding mode, the fixing protrusion of the second blade is coupled to the second fixing groove.

12. The foldable blade assembly according to claim 1, wherein, The second shaft is connected to the third shaft via a bearing assembly.

13. The foldable blade assembly according to claim 1, wherein, One of the first blade and the second blade includes a locking protrusion, and the other of the first blade and the second blade includes a locking groove, such that in a vertical movement mode, the locking protrusion is coupled to the locking groove.

14. The foldable blade assembly according to claim 13, in, The locking protrusion is formed to extend along the longitudinal axis of one of the first blade and the second blade, and The locking groove is formed to be recessed on the longitudinal axis of the other of the first blade and the second blade.

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