Propeller

Abstract

To prevent a blade from being unintentionally folded.SOLUTION: A propeller includes a hub, a blade, a first engagement portion, and a second engagement portion. The blade is mounted so as to be movable in a radial direction with respect to the hub. The blade is pivotally mounted to the hub. The first engaging portion is formed on the hub. The second engagement portion is formed on the blade. The second engagement portion is configured to engage with the first engagement portion to restrict pivoting of the blade with respect to the hub when the blade moves radially outward. The second engagement portion is configured to be disengaged from the first engagement portion when the blade moves radially inward.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Propellers used in drones and the like have a hub and blades (see, for example, Patent Document 1). The blades are fastened to the hub with bolts or the like. The blades are folded when the propeller is not rotating, and are configured to open due to centrifugal force when the propeller begins to rotate. In other words, the bolts fasten the blades to the hub with a fastening force that allows the blades to rotate relative to the hub. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-184048 Summary of the Invention [Problem to be solved by the invention]

[0004] In the propeller described above, there is a risk that the blades may fold due to acceleration or deceleration during rotation of the propeller. In addition, if the blades fold unintentionally, a response delay occurs, leading to problems such as deterioration of controllability and power consumption.

[0005] An object of the present invention is to prevent the blade from unintentionally folding. [Means for solving the problem]

[0006] A propeller according to a first aspect includes a hub, blades, first engagement portions, and second engagement portions. The blades are attached to the hub so as to be radially movable. The blades are attached to the hub so as to be pivotable. The first engagement portions are formed on the hub. The second engagement portions are formed on the blades. The second engagement portions are configured to engage with the first engagement portions as the blades move radially outward, thereby restricting the pivoting of the blades relative to the hub. The second engagement portions are configured to disengage from the first engagement portions as the blades move radially inward.

[0007] With this configuration, when the propeller rotates, the blades move radially outward due to centrifugal force, engaging the first and second engagement portions. As a result, the blades are restricted from pivoting relative to the hub, preventing them from unintentionally folding. When the propeller stops, the blades can be moved radially inward to disengage the first and second engagement portions, allowing them to fold.

[0008] The propeller according to the second aspect is the propeller according to the first aspect, but is configured as follows: The hub has an upper hub portion and a lower hub portion. The upper hub portion is disposed above the blades. The lower hub portion is disposed below the blades.

[0009] A propeller according to a third aspect is the propeller according to the second aspect, and is configured as follows: The first engagement portion is formed in the upper hub portion.

[0010] A propeller according to a fourth aspect is the propeller according to the second or third aspect, configured as follows: The hub has a lower hub portion that is disposed below the blades.

[0011] A propeller according to a fifth aspect is the propeller according to any one of the first to fourth aspects, configured as follows: The first engagement portion is one of a recessed portion and a protruding portion formed on the hub, and the second engagement portion is the other of the recessed portion and the protruding portion formed on the blade.

[0012] A propeller according to a sixth aspect is the propeller according to the fifth aspect, and is configured as follows: The recess has a pair of opposing inner wall surfaces that are inclined so as to gradually separate from each other toward the protrusion.

[0013] A propeller according to a seventh aspect is the propeller according to any one of the first to sixth aspects, further comprising a swivel shaft. The swivel shaft extends axially from one of the hub and the blades. The other of the hub and the blades has a slot. The slot extends radially. The slot guides the swivel shaft so that it can move radially.

[0014] A propeller according to an eighth aspect is the propeller according to the seventh aspect, configured as follows: the turning shaft extends axially from the hub, and the blades have elongated holes.

[0015] A rotary wing aircraft according to a ninth aspect includes the propeller according to any one of the first to eighth aspects, and a prime mover configured to rotate the propeller. [Effects of the Invention]

[0016] According to the present invention, it is possible to prevent the blade from being unintentionally folded. [Brief explanation of the drawings]

[0017] [Figure 1] Plan view of a rotorcraft. [Figure 2] Plan view of the propeller. [Figure 3] Cross-sectional view of line III-III in Figure 2. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] Bottom view of the blade. [Figure 7] FIG. 10 is a cross-sectional view of a propeller according to a modified example. [Figure 8] FIG. 10 is a cross-sectional view of a propeller according to a modified example. [Figure 9]FIG. 10 is a plan view of a lower hub portion according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0018] The rotorcraft 100 and propeller 105 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 O of the propeller 105 extends. The circumferential direction refers to the circumferential direction of a circle centered on the rotation axis O, and the radial direction refers to the radial direction of a circle centered on the rotation axis O.

[0019] <Rotorcraft> As shown in Fig. 1, the rotary-wing aircraft 100 has a main body 101, multiple arms 102, and multiple rotors 103. Each rotor 103 has an electric motor 104 (an example of a prime mover) and a propeller 105. 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.

[0020] 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.

[0021] The electric motors 104 are configured to rotate the propellers 105. The rotation direction differs depending on the electric motor 104. For example, the electric motors 104 of the rotors 103 at the top right and bottom left in FIG. 1 rotate clockwise, while the electric motors 104 of the rotors 103 at the top left and bottom right in FIG. 1 rotate counterclockwise.

[0022] <Propeller> Fig. 2 is a plan view of the propeller 105, and Fig. 3 is a cross-sectional view taken along line II-II in Fig. 2. In Figs. 2 and 3, the right blade 3 is shown moved radially inward, and the left blade 3 is shown moved radially outward.

[0023] As shown in FIGS. 2 and 3, the propeller 105 has a hub 2, a pair of blades 3, and a pair of bolts 4 (an example of a rotating shaft).

[0024] <hub> The hub 2 is attached to the electric motor 104. More specifically, the hub 2 is attached to the rotor of the electric motor 104. Therefore, the hub 2 is rotatably arranged. The hub 2 also supports each of the blades 3.

[0025] The hub 2 has an upper hub portion 21 and a lower hub portion 22. The upper hub portion 21 is disposed above each blade 3. The lower hub portion 22 is disposed below each blade 3. That is, each blade 3 is sandwiched between the upper hub portion 21 and the lower hub portion 22 in the vertical direction. The upper hub portion 21 and the lower hub portion 22 are fastened together by a pair of bolts 4. The lower hub portion 22 is attached to the electric motor 104 by a plurality of bolts (not shown) or the like.

[0026] The upper hub portion 21 has a pair of elongated holes 211. Each elongated hole 211 extends in the radial direction. The lower hub portion 22 has a pair of elongated holes 221. Each elongated hole 221 extends in the radial direction. The elongated holes 211 of the upper hub portion 21 and the elongated holes 221 of the lower hub portion 22 overlap when viewed in the axial direction. The width of each of the elongated holes 211, 221 is approximately the same as the diameter of the bolt 4.

[0027] <Blade> A pair of blades 3 extend radially from the hub 2. Each blade 3 is attached to the hub 2 at its base end. Each blade 3 has a through hole 31 at its base end. The bolt 4 extends through this through hole 31. That is, the bolt 4 extends axially from the blade 3. More specifically, the bolt 4 extends upward and downward from the blade 3. The bolt 4 is configured to move radially together with the blade 3.

[0028] Each blade 3 is rotatable relative to the hub 2. That is, each blade 3 is attached so as to be rotatable relative to the hub 2. Each blade 3 is rotatable around the bolt 4. The blade 3 may rotate together with the bolt 4, or may rotate relative to the bolt 4. The diameter of the through hole 31 is approximately the same as the diameter of the bolt 4.

[0029] A portion of each bolt 4 is housed in the elongated holes 211, 221 of the upper hub portion 21 and the lower hub portion 22. More specifically, the upper end of each bolt 4 is housed in the elongated hole 211 of the upper hub portion 21. The lower end of each bolt 4 is housed in the elongated hole 221 of the lower hub portion 22.

[0030] The bolt 4 is movable radially within the elongated holes 211, 221 of the upper hub portion 21 and the lower hub portion 22. Each of the elongated holes 211, 221 is configured to guide the bolt 4 so that it can move radially. Therefore, each blade 3 is movable radially relative to the hub 2 together with the bolt 4. In other words, each blade 3 is attached so as to be movable radially relative to the hub 2. In detail, each blade 3 can move radially outward relative to the hub 2, as in the blade 3 on the left in FIGS. 2 and 3, or can move radially inward relative to the hub 2, as in the blade 3 on the right in FIGS. 2 and 3.

[0031] <First and second engagement portions> Fig. 4 is a plan view of the lower hub portion 22, Fig. 5 is a perspective view of the lower hub portion 22, and Fig. 6 is a bottom view of the pair of blades 3. As shown in Figs. 3 to 6, the propeller 105 further has a pair of first engagement portions 5 and a pair of second engagement portions 6.

[0032] As shown in Figures 3 to 5, each first engagement portion 5 is formed on the hub 2. More specifically, each first engagement portion 5 is formed on the lower hub portion 22. Each first engagement portion 5 is a recess. Each first engagement portion 5 opens radially inward. Each first engagement portion 5 also opens upward. Each first engagement portion 5 has a pair of inner wall surfaces 51 that face each other in the circumferential direction.

[0033] As shown in Figures 3 and 6, each second engagement portion 6 is formed on each blade 3. One second engagement portion 6 is formed for each blade 3. Each second engagement portion 6 is a convex portion. Each second engagement portion 6 protrudes downward from the corresponding blade 3. That is, each second engagement portion 6 protrudes toward the lower hub portion 22.

[0034] Each second engagement portion 6 faces a corresponding first engagement portion 5 in the radial direction. Each second engagement portion 6 is configured to engage with a corresponding first engagement portion 5. Preferably, each second engagement portion 6 is configured to fit into a corresponding first engagement portion 5.

[0035] When the propeller 105 rotates and centrifugal force acts on the blades 3, the blades 3 move radially outward, as shown in the left blade 3 in FIGS. 2 and 3 . Alternatively, a user moves the blades 3 radially outward when using the rotary-wing aircraft 100. As the blades 3 move radially outward in this manner, the second engagement portions 6 engage with the first engagement portions 5. As the second engagement portions 6 engage with the first engagement portions 5, the rotation of the blades 3 relative to the hub 2 is restricted. In other words, when the second engagement portions 6 engage with the first engagement portions 5, the blades 3 cannot rotate relative to the hub 2. This prevents the blades 3 from folding even when the propeller 105 suddenly accelerates or decelerates while rotating.

[0036] When storing the propeller 105, the user moves the blades 3 radially inward, as shown in the right-hand blade 3 in Figures 2 and 3. By moving the blades 3 radially inward in this manner, the second engagement portions 6 are disengaged from the first engagement portions 5. As a result, the blades 3 become rotatable relative to the hub 2. Therefore, the blades 3 can be rotated relative to the hub 2 to fold them, thereby making the propeller 105 more compact.

[0037] [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.

[0038] (a) In the above embodiment, the propeller 105 has two blades 3, but the propeller 105 may have only one blade 3, or may have three or more blades 3.

[0039] (b) As shown in Figure 7, each first engagement portion 5 may be formed on the upper hub portion 21. In this case, the second engagement portion 6 protrudes upward from each blade 3. With this configuration, each blade 3 moves upward when rotated, allowing the first engagement portion 5 and the second engagement portion 6 to be engaged with each other more stably.

[0040] (c) In the above embodiment, the first engagement portion 5 is a recess and the second engagement portion 6 is a protrusion, but the first engagement portion 5 may be a protrusion and the second engagement portion 6 may be a recess. That is, the blade 3 may have a recess and the hub 2 may have a protrusion. In this case, the recess formed in the blade 3 opens radially outward.

[0041] (d) In the above embodiment, the bolts 4 extend in the axial direction from the blades 3, and the elongated holes 211, 221 are formed in the hub 2. However, the configuration of the propeller 105 is not limited to this. For example, as shown in FIG. 8 , the bolts 4 may extend in the axial direction from the upper hub portion 21 and the lower hub portion 22, and the elongated holes 32 may be formed in the blades 3. In this case, the upper hub portion 21 and the lower hub portion 22 have through holes 212, 222, and the bolts 4 fit into the through holes 212, 222 of the upper hub portion 21 and the lower hub portion 22. Therefore, the bolts 4 cannot move in the radial direction relative to the hub 2. However, the blades 3 are movable in the radial direction relative to the bolts 4.

[0042] (e) In the above embodiment, the bolt 4 is exemplified as the pivot shaft, but the pivot shaft does not have to be the bolt 4. For example, a pin may extend vertically from the blade 3 instead of the bolt 4. In this case, the pin may be a separate member from the blade 3, or may be formed integrally with the blade 3 as a single member.

[0043] (f) The shape of the recess formed as the first engagement portion 5 is not limited to the shape in the above embodiment and can take various shapes. For example, as shown in Fig. 9, a pair of inner wall surfaces 51 defining the recess of the first engagement portion 5 may be inclined so as to gradually separate toward the second engagement portion 6. In this case, the side surfaces of the protrusion of the second engagement portion 6 are also inclined in the same way as the pair of inner wall surfaces 51.

[0044] (f) In the above embodiment, the hub 2 has an upper hub portion 21 and a lower hub portion 22, but the configuration of the hub 2 is not limited to this. For example, the hub 2 may have only the upper hub portion 21 and not the lower hub portion 22.

[0045] (g) In the above embodiment, the propeller 105 has a pair of first engagement portions 5 and a pair of second engagement portions 6, but the number of first engagement portions 5 and second engagement portions 6 is not limited to this. For example, the number of first engagement portions 5 and second engagement portions 6 may be three or more. [Explanation of symbols]

[0046] 2: Hub 21: Upper hub part 211: Long hole 22: Lower hub part 221: Long hole 3: Blade 4: Bolt 5: First engagement portion 51: Inner wall surface 6: Second engagement portion 100:Rotorcraft 104: Electric motor 105: Propeller

Claims

1. Hub and a blade mounted to the hub so as to be radially movable and pivotable relative to the hub; a first engagement portion formed on the hub; a second engaging portion formed on the blade, configured to engage with the first engaging portion when the blade moves radially outward to restrict rotation of the blade relative to the hub, and to disengage from the first engaging portion when the blade moves radially inward; A propeller.

2. The hub has an upper hub portion disposed above the blade.

2. The propeller of claim 1.

3. The first engagement portion is formed on the upper hub portion.

3. The propeller of claim 2.

4. The hub has a lower hub portion disposed below the blade.

3. The propeller of claim 2.

5. the first engagement portion is one of a recess and a protrusion formed on the hub, the second engagement portion is the other of the recess and the protrusion formed on the blade; 2. The propeller of claim 1.

6. The recess has a pair of opposing inner wall surfaces, The pair of inner wall surfaces are inclined so as to gradually move apart toward the convex portion.

6. The propeller of claim 5.

7. a pivot shaft extending axially from one of the hub and the blade; The other of the hub and the blade has a long hole extending radially to guide the rotating shaft so as to be radially movable.

2. The propeller of claim 1.

8. The pivot shaft extends axially from the hub; The blade has the slot.

8. The propeller of claim 7.

9. A propeller according to any one of claims 1 to 8; a prime mover configured to rotate the propeller; and A rotorcraft comprising:

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