Hub assembly, propeller, aircraft

Abstract

The application discloses a hub assembly, a propeller and an aircraft, and relates to the technical field of propellers, wherein the hub assembly comprises a mounting seat, a hub and a flap hinge; the mounting seat is drivingly connected to an output end of a power device; the hub is used for mounting propeller blades; the flap hinge comprises an elastic bearing; and the hub is rotationally connected to the mounting seat through the elastic bearing. The technical scheme provided by the application can reduce the maintenance difficulty and cost of the propeller.

Description

Technical Field

[0001] This invention relates to the field of propeller technology, and particularly to a hub assembly, a propeller, and an aircraft. Background Technology

[0002] In related technologies, semi-rigid rotor hubs used in aircraft typically incorporate flapping hinges and pitch hinges, utilizing cyclic pitch mechanisms to control the pitch angle of the blades, thereby controlling the magnitude and direction of the rotor's aerodynamic forces. Currently, semi-rigid rotor hubs often employ rolling bearings in critical positions such as the flapping hinges and pitch hinges. However, rolling bearings require excellent sealing and frequent lubrication, leading to difficulties and high maintenance costs for the propellers. Summary of the Invention

[0003] The main objective of this invention is to provide a hub assembly, a propeller, and an aircraft that aims to reduce the difficulty and cost of propeller maintenance.

[0004] To achieve the above objectives, the present invention proposes a rotor hub assembly for use in the propeller of an aircraft, wherein the aircraft is equipped with a power unit that drives and connects to the propeller, and the rotor hub assembly includes:

[0005] Mounting bracket, drive connection to the output end of the power unit;

[0006] The hub is used to mount the propeller blades;

[0007] A flapping hinge, the flapping hinge including a resilient bearing, the propeller hub being rotatably connected to the mounting base via the resilient bearing.

[0008] In one embodiment, the elastic bearing is mounted on the mounting base, and the flapping hinge further includes a flapping shaft, which is rotatably connected to the mounting base via the elastic bearing. The flapping shaft is fixedly connected to the propeller hub so that the flapping torque of the propeller hub can be transmitted to the elastic bearing via the flapping shaft.

[0009] In one embodiment, the propeller hub is provided with a first through hole, the flapping hinge further includes a flapping bushing, the flapping shaft has a shaft end section corresponding to the flapping bushing, the outer peripheral surface of the flapping bushing is connected to the hole wall of the first through hole, the inner peripheral surface of the flapping bushing is connected to the outer peripheral surface of the shaft end section, and the flapping torque of the propeller hub can be transmitted to the shaft end section through the flapping bushing.

[0010] In one embodiment, the inner circumferential surface of the swinging bushing and the outer circumferential surface of the shaft end section are configured as matching prismatic or elliptical cylindrical surfaces, or the inner circumferential surface of the swinging bushing and the outer circumferential surface of the shaft end section are configured as interference-fit cylindrical surfaces, so as to realize the transmission of swinging torque from the swinging bushing to the shaft end section.

[0011] In one embodiment, the outer peripheral surface of the waving bushing and the wall surface of the first through hole are configured as an interference fit cylindrical surface, or the outer peripheral surface of the waving bushing and the wall surface of the first through hole are configured as a matching prism surface or elliptical cylindrical surface, so as to realize the transmission of waving torque from the propeller hub to the waving bushing.

[0012] In one embodiment, the first through hole includes a middle section and an end section of the through hole that connects to the middle section. The diameter of the end section of the through hole is larger than that of the middle section of the through hole, so as to form a stepped surface at the connection between the end section of the through hole and the middle section of the through hole. One end of the swinging bushing extends into the end section of the through hole and abuts against the stepped surface, and the other end of the swinging bushing abuts against the end face of the elastic bearing.

[0013] In one embodiment, the mounting base is provided with a first mounting hole, and the elastic bearing includes an outer bearing ring, an inner bearing ring, and a bearing elastic body. The bearing elastic body is disposed between the outer bearing ring and the inner bearing ring. The outer bearing ring is fixedly connected to the wall surface of the first mounting hole, and the inner bearing ring is sleeved on the shaft end section. The swinging torque on the shaft end section can be transmitted to the inner bearing ring and then to the bearing elastic body through the inner bearing ring.

[0014] In one embodiment, the inner circumferential surface of the bearing inner ring and the outer circumferential surface of the shaft end section are configured as matching prismatic or elliptical cylindrical surfaces, or the inner circumferential surface of the bearing inner ring and the outer circumferential surface of the shaft end section are configured as interference-fit cylindrical surfaces to achieve the transmission of swing torque from the shaft end section to the bearing inner ring.

[0015] In one embodiment, the mounting base has two opposing first mounting holes for mounting the elastic bearing. The propeller hub is located at the interval between the two first mounting holes and has a first through hole for the swing shaft to pass through. The two ends of the swing shaft are respectively connected to the elastic bearings on the two first mounting holes.

[0016] In one embodiment, a bearing key is provided on the outer peripheral surface of the elastic bearing, and a notch is provided on the wall of the first mounting hole corresponding to the bearing key, and the bearing key is inserted into the notch along the axial direction of the first mounting hole.

[0017] In one embodiment, the swing hinge further includes a locking nut that is locked onto the end of the swing shaft that passes through the first mounting hole.

[0018] In one embodiment, the elastic bearing is mounted on the propeller hub, and the flapping hinge further includes a flapping shaft, which is fixedly connected to the mounting base. The propeller hub is rotatably connected to the flapping shaft via the elastic bearing.

[0019] In one embodiment, the propeller hub is provided with a third mounting hole. The elastic bearing includes an outer bearing ring, an inner bearing ring, and a bearing elastic body. The bearing elastic body is disposed between the outer bearing ring and the inner bearing ring. The outer bearing ring is fixedly connected to the wall surface of the third mounting hole. The flapping torque of the propeller hub can be transmitted to the outer bearing ring through the wall surface of the third mounting hole, and then to the bearing elastic body through the outer bearing ring. The inner bearing ring is fixedly sleeved on the flapping shaft, and is relatively fixedly connected to the mounting base through the flapping shaft.

[0020] In one embodiment, the resilient bearing includes an outer bearing ring, an inner bearing ring, and a bearing elastomer, wherein the bearing elastomer is disposed between the outer bearing ring and the inner bearing ring; the outer peripheral surface and / or the inner peripheral surface of the bearing elastomer is configured as a frustoconical surface, and / or the bearing elastomer includes alternating layers of elastic layers and metal layers, wherein the elastic layers and the metal layers are integrally formed by layered vulcanization.

[0021] In one embodiment, the propeller hub assembly further includes at least two counterweight structures disposed on the propeller hub, the at least two counterweight structures being respectively disposed on both sides of the axis of the flapping hinge; the counterweight structure includes a counterweight block and a counterweight fastener, the counterweight block being mounted on the upper end surface of the propeller hub by the counterweight fastener.

[0022] The present invention also proposes a propeller comprising two blades and the aforementioned hub assembly, wherein the end of the hub is provided with two mounting positions and the two blades are respectively disposed in the two mounting positions.

[0023] The present invention also proposes an aircraft, including an airframe, a power unit and the aforementioned propeller, wherein the power unit is disposed in the airframe and drives a mounting base connected to the propeller.

[0024] In one embodiment, the aircraft is configured as an electric vertical takeoff and landing (EVTOL) aircraft.

[0025] The technical solution of this invention uses a flexible bearing instead of a traditional rolling bearing (such as a ball bearing or roller bearing) as the bearing for the flapping hinge. This saves on heavy and complex steel balls, rollers, and cages, making the propeller hub assembly more compact and simpler. More importantly, the flexible bearing in this critical position requires no lubrication or sealing, and has long inspection intervals. Therefore, it effectively improves the maintenance difficulties and high maintenance costs caused by the need for good sealing and frequent lubrication of traditional rolling bearings. In other words, it can reduce the difficulty and cost of propeller maintenance. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a structure of an embodiment of the propeller hub assembly provided by the present invention;

[0028] Figure 2 for Figure 1 Top view of the embodiment shown;

[0029] Figure 3 for Figure 1 A cross-sectional view of the embodiment shown;

[0030] Figure 4 for Figure 1 Another cross-sectional view of the embodiment shown;

[0031] Figure 5 for Figure 1 A partial cross-sectional view of the damping structure in the illustrated embodiment;

[0032] Figure 6 for Figure 1 The illustrated embodiment is shown in a partial cross-sectional view at the first lug.

[0033] Figure 7 for Figure 3 A partial sectional view of the waving shaft, waving shaft sleeve, and first through hole;

[0034] Figure 8 This is a cross-sectional view of another embodiment of the propeller hub assembly provided by the present invention.

[0035] Explanation of icon numbers:

[0036] 100. Mounting base; 101. Mounting space; 110. First lug; 111. First mounting hole; 112. Notch; 120. Second lug; 121. Second mounting hole;

[0037] 200, hub; 201, mounting position; 203, first through hole; 204, second through hole; 205, middle section of through hole; 206, end section of through hole; 207, stepped surface; 208, third mounting hole;

[0038] 300. Swinging hinge; 310. Swinging shaft; 311. Shaft middle section; 312. Shaft end section; 320. Elastic bearing; 321. Bearing outer ring; 322. Bearing inner ring; 323. Bearing elastomer; 324. Bearing key; 330. Swinging bushing; 340. Locking nut;

[0039] 400. Damping structure; 401. Damping part; 410. Elastic damping component; 411. Outer ring sleeve; 412. Inner ring sleeve; 413. Damping elastomer; 414. Relief hole; 415. Concave curved surface; 420. Damping shaft; 430. Damping shaft sleeve;

[0040] 500, limiting component; 501, limiting surface;

[0041] 600. Counterweight structure; 610. Counterweight block; 620. Counterweight fastener;

[0042] 700. Paddle blades.

[0043] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0046] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0047] In related technologies, semi-rigid rotor hubs used in aircraft typically incorporate flapping hinges and pitch hinges, utilizing cyclic pitch mechanisms to control the blade pitch angle, thereby controlling the magnitude and direction of the rotor's aerodynamic forces. Current semi-rigid rotor hubs suffer from several drawbacks. First, the large flapping amplitude of the blades necessitates a high placement of the propeller during the design phase, meaning the propeller is positioned far from the aircraft fuselage to avoid collisions. This distance results in higher cruising drag. Second, the low linearity of the blade flapping motion hinders aircraft control. Furthermore, critical components like the flapping and pitch hinges often employ rolling bearings, which require excellent sealing and frequent lubrication, leading to difficult and costly propeller maintenance.

[0048] In view of this, the present invention proposes a propeller hub assembly that can solve at least one of the above-mentioned technical problems. Specifically, the propeller hub assembly is applied to the propeller of an aircraft, the aircraft having a power unit that drives and connects to the propeller, and the propeller can rotate under the output torque of the power unit.

[0049] Please see Figure 1 and Figure 2 In one embodiment of the present invention, the propeller hub assembly includes a mounting base 100, a propeller hub 200, and a flapping hinge 300. The mounting base 100 is connected to the output end of the power unit, and the propeller hub 200 is used to mount the propeller blades 700 of the aircraft. The propeller hub 200 is mounted on the mounting base 100 via the flapping hinge 300. The propeller hub 200 can also be referred to as a propeller clamp. The number of propeller blades 700 can also be two or more; the present invention does not specifically limit this.

[0050] Optionally, the two blades 700 are assembled as a single unit via a hub 200 and share a flapping hinge 300. That is, in this embodiment, the two blades 700 are assembled as a single unit via a hub 200 and can perform a unified flapping motion relative to a common flapping hinge 300, resulting in a seesaw configuration (i.e., a semi-rigid configuration) for the propeller. On one hand, compared to a fully hinged hub 200, the seesaw-type hub 200 of this invention simplifies the construction of the hub assembly by eliminating the flapping hinge and damper, thus reducing the structural complexity of the propeller and lowering its manufacturing and maintenance costs. On the other hand, compared to a fully rigid hub 200, the seesaw-type hub 200 of this invention has a degree of freedom for flapping through the flapping hinge 300 to unload aerodynamic forces, therefore requiring lower stiffness from the blades 700. Ordinary blades 700 can be directly applied to this hub assembly without special modification, thus making the hub assembly highly versatile.

[0051] Of course, in other embodiments, two (or more) blades 700 may be rotatably connected to the hub 200 independently, that is, two (or more) blades 700 may each be equipped with their own flapping hinges 300, rather than sharing a flapping hinge 300.

[0052] It should be noted that the rotor hub assembly of the present invention is not limited to any particular aircraft type; it can be an eVTOL (Electric Vertical Takeoff and Landing) aircraft, a helicopter, or other similar aircraft. The configuration of the eVTOL includes, but is not limited to, multi-rotor configurations, compound wing configurations, and tiltrotor configurations. Taking a compound wing eVTOL as an example, the aircraft includes a fixed wing and multiple rotors, including a lift rotor, and the rotor hub assembly of the present invention can be applied to this lift rotor.

[0053] Please see Figure 3 In one embodiment, the flapping hinge 300 includes a resilient bearing 320, and the paddle hub 200 is rotatably connected to the mounting base 100 via the resilient bearing 320.

[0054] It should be noted that the elastic bearing 320 of this embodiment can be applied to products where two blades 700 share a flapping hinge 300, or to products where two (or more) blades 700 are each equipped with their own flapping hinge 300. That is, the elastic bearing 320 of this embodiment does not necessarily rely on other technical solutions for implementation.

[0055] In this embodiment, using a flexible bearing 320 instead of a traditional rolling bearing (such as a ball bearing or roller bearing) as the bearing for the flapping hinge 300 saves on heavy and complex steel balls, rollers, and cages, making the hub assembly more compact and simpler. More importantly, the flexible bearing 320 in this critical location requires no lubrication or sealing and has long inspection intervals, thus effectively improving the maintenance difficulties and high maintenance costs caused by the need for good sealing and frequent lubrication of traditional rolling bearings. In other words, it can reduce the maintenance difficulty and cost of the propeller.

[0056] Furthermore, when the flapping torque on the rotor hub 200 is transmitted to the elastic bearing 320, the bearing elastomer 323 on the elastic bearing 320 can undergo elastic deformation and generate a drag torque to counteract part or all of the flapping torque, thereby reducing the rigidity requirements on the rotor blade 700. Secondly, the elastic bearing 320 can also filter high-frequency vibrations from the rotor blade 700, thereby improving the passenger comfort of the aircraft.

[0057] In one embodiment, the resilient bearing 320 includes an outer bearing ring 321, an inner bearing ring 322, and a bearing elastomer 323, with the bearing elastomer 323 disposed between the outer bearing ring 321 and the inner bearing ring 322. Thus, by providing the outer bearing ring 321 and the inner bearing ring 322, the resilient bearing 320 can be easily installed between the propeller hub 200 and the mounting base 100. Of course, in other embodiments, the resilient bearing 320 may only include the bearing elastomer 323, or it may only include the bearing elastomer 323 and the outer bearing ring 321, or it may only include the bearing elastomer 323 and the inner bearing ring 322.

[0058] Optionally, the outer and / or inner circumferential surfaces of the bearing elastomer 323 are configured as frustum conical surfaces. Specifically, in this embodiment, both the outer and inner circumferential surfaces of the bearing elastomer 323 are frustum conical surfaces, and the apex angle of the frustum conical surface can range from 20° to 40°, for example, values ​​of 20°, 25°, 30°, or 35°, etc., and the diameters of the two frustum conical surfaces gradually increase in the same direction; the inner circumferential surface of the bearing outer ring 321 and the outer circumferential surface of the bearing inner ring 322 are both adapted to be frustum conical surfaces. In this way, the bearing elastomer 323 has both excellent radial load-bearing capacity and axial load-bearing capacity. Of course, in other embodiments, the outer and inner circumferential surfaces of the bearing elastomer 323 can also be configured as cylindrical surfaces.

[0059] The bearing elastomer 323 can have various structural forms. For example, it can include alternating layers of elastic and metal layers, which are integrally formed through layered vulcanization. Specifically, the elastic layer can be made of rubber, and the metal layer can be made of steel. The bearing elastomer 323 employs a layered vulcanization process, alternating layers of rubber and reinforcing steel, and is integrally vulcanized in a high-temperature, high-pressure mold. This results in a strong chemical bond between the rubber and steel, giving the elastic bearing 320 advantages such as high load-bearing capacity, large displacement flexibility, and long-term reliability. Of course, in other embodiments, the bearing elastomer 323 can also adopt other structural forms, such as omitting the metal layer.

[0060] It is understood that the elastomeric bearing 320 can be installed in various ways; for example, please refer to [link to relevant documentation]. Figure 3 In one embodiment, the elastic bearing 320 is mounted on the mounting base 100. Of course, in other embodiments, the elastic bearing 320 may also be mounted on the propeller hub 200.

[0061] In an embodiment where the elastic bearing 320 is mounted on the mounting base 100, the flapping hinge 300 may optionally include a flapping shaft 310, which is rotatably connected to the mounting base 100 via the elastic bearing 320. The flapping shaft 310 is fixedly connected to the propeller hub 200 so that the flapping torque of the propeller hub 200 can be transmitted to the elastic bearing 320 via the flapping shaft 310.

[0062] It should be noted that the "fixed connection" in the embodiments of the present invention does not specifically refer to a non-detachable connection, such as a welded connection, but rather includes situations where there is no relative rotation between the two components. For example, in this embodiment, the waving shaft 310 is fixedly connected to the paddle hub 200, meaning that the waving shaft 310 cannot rotate relative to the paddle hub 200 around its own axis. In this case, the waving shaft 310 and the paddle hub 200 can be either detachably connected or fixed together by welding or other means.

[0063] Please see Figure 2 , Figure 3 , Figure 6 and Figure 7In one embodiment, optionally, the propeller hub 200 is provided with a first through hole 203, and the flapping hinge 300 further includes a flapping bushing 330 sleeved on the flapping shaft 310. The flapping shaft 310 has a shaft end section 312 corresponding to the flapping bushing 330. The outer peripheral surface of the flapping bushing 330 is connected to the hole wall of the first through hole 203, and the inner peripheral surface of the flapping bushing 330 is connected to the outer peripheral surface of the shaft end section 312. The flapping torque of the propeller hub 200 can be transmitted to the shaft end section 312 through the flapping bushing 330. Thus, by adding the flapping bushing 330 and allowing the flapping torque to be indirectly transmitted to the flapping shaft 310 through the flapping bushing 330, the risk of damage to the flapping shaft 310 and the propeller hub 200 structure can be reduced. Of course, in other embodiments, the flapping bushing 330 may not be provided.

[0064] Optionally, the inner circumferential surface of the swinging bushing 330 and the outer circumferential surface of the shaft end section 312 are configured as matching prismatic surfaces to achieve the transmission of swinging torque from the swinging bushing 330 to the shaft end section 312. For example, they can be configured as hexagonal prisms, that is, the cross-sectional shape of the inner circumferential surface of the bearing inner ring 322 and the outer circumferential surface of the shaft end section 312 is hexagonal, and can be clearance fit; they can also be configured as quadrangular prisms, pentagonal prisms, or other prismatic surfaces, or even as regular curved surfaces such as cylindrical surfaces (interference fit), elliptical cylindrical surfaces, or other irregular curved surfaces. In this way, the structure is simple and easy to manufacture, and can effectively and stably transmit swinging torque.

[0065] Optionally, the outer peripheral surface of the flapping bushing 330 and the wall surface of the first through hole 203 are configured as interference-fit cylindrical surfaces, that is, the flapping bushing 330 and the first through hole 203 are interference-fitted to realize the transmission of flapping torque from the propeller hub 200 to the flapping bushing 330. In other words, the flapping bushing 330 is interference-fitted into the first through hole 203, which has a simple structure and is easy to assemble. Furthermore, when the flapping torque exceeds the design load, a portion of the flapping torque can be unloaded through the relative circumferential movement between the flapping bushing 330 and the first through hole 203, thus avoiding the problem that the overloaded flapping torque is essentially absorbed by the elastic bearing 320, leading to easy damage to the elastic bearing 320. Of course, in other embodiments, the outer peripheral surface of the flapping bushing 330 and the wall surface of the first through hole 203 can be configured as compatible prismatic or elliptical cylindrical surfaces, etc.

[0066] It is understood that in this embodiment, the inner circumferential surface of the waving bushing 330 and the outer circumferential surface of the shaft end section 312 are configured as matching prismatic surfaces, and the outer circumferential surface of the waving bushing 330 and the hole wall surface of the first through hole 203 are configured as interference-fit cylindrical surfaces, so that the waving shaft 310 cannot rotate relative to the propeller hub 200 around its own axis, thereby allowing the waving torque to be transmitted from the propeller hub 200 through the waving bushing 330 to the shaft end section 312. At this time, the waving shaft 310 and the waving bushing 330 can be detachably connected, and the waving bushing 330 and the propeller hub 200 can also be detachably connected.

[0067] Optionally, the flapping torque on the shaft end section 312 can be transmitted to the bearing inner ring 322, and then to the bearing elastomer 323 via the bearing inner ring 322. That is, in this embodiment, the flapping torque on the rotor hub 200 is first transmitted to the shaft end section 312 of the flapping shaft 310 via the flapping bushing 330, and then to the bearing inner ring 322 and the bearing elastomer 323 via the shaft end section 312. Finally, the elastic deformation torque of the bearing elastomer 323 of the elastic bearing 320 is used to offset part or all of the flapping torque. In this way, through this clear flapping torque transmission path, the flapping torque can be transmitted to the elastic bearing 320 in a timely and effective manner, thereby offsetting the flapping torque with the help of the elastic bearing 320, thus reducing the rigidity requirements of the rotor blade 700.

[0068] Of course, in other embodiments, the swinging torque can be directly transmitted to the bearing inner ring 322 through the swinging bushing 330, or the swinging torque can be transmitted to the bearing inner ring 322 through both the swinging bushing 330 and the swinging shaft 310.

[0069] It is understood that in the embodiment where the elastic bearing 320 is mounted on the propeller hub 200, the flapping torque on the propeller hub 200 can be directly transmitted to the bearing elastomer 323 through the outer bearing ring 321, without needing to go through the flapping shaft 310. In this case, the outer bearing ring 321 is relatively fixedly connected to the propeller hub 200, and the inner bearing ring 322 is relatively fixedly mounted on the mounting base 100 via the flapping shaft 310. When the propeller hub 200 flaps around the axis of the flapping shaft 310, the outer bearing ring 321 and the inner bearing ring 322 will rotate relative to each other, thereby causing the bearing elastomer 323 located between the outer bearing ring 321 and the inner bearing ring 322 to undergo elastic deformation and generate a resisting torque that counteracts the flapping torque.

[0070] Optionally, the inner circumferential surface of the bearing inner ring 322 and the outer circumferential surface of the shaft end section 312 are configured as matching prismatic surfaces to achieve the transmission of swing torque from the shaft end section 312 to the bearing inner ring 322. For example, they can be configured as hexagonal prisms, that is, the cross-sectional shape of the inner circumferential surface of the bearing inner ring 322 and the outer circumferential surface of the shaft end section 312 is hexagonal; they can also be configured as quadrangular prisms, pentagonal prisms, or other prismatic surfaces, or even as regular curved surfaces such as cylindrical surfaces (interference fit), elliptical cylindrical surfaces, or other irregular curved surfaces. In this way, the structure is simple and easy to manufacture, and can effectively and stably transmit swing torque.

[0071] The mounting base 100 has various structural forms; for example, please refer to... Figure 3In one embodiment, optionally, the mounting base 100 has two opposing first mounting holes 111 for mounting elastic bearings 320. The propeller hub 200 is located at the interval between the two first mounting holes 111, and the propeller hub 200 has a first through hole 203 for the swing shaft 310 to pass through. The two ends of the swing shaft 310 are respectively connected to the elastic bearings 320 on the two first mounting holes 111. Thus, the structure is simple and easy to install.

[0072] In one embodiment where the outer and inner circumferential surfaces of the bearing elastomer 323 are configured as frustoconical surfaces, the small ends of the two bearing elastomers 323 are arranged facing each other. That is, the two elastic bearings 320 are installed opposite each other, which helps to improve the axial stability of the swing shaft 310.

[0073] Please refer to the following: Figure 2 Optionally, the mounting base 100 includes two opposing first lugs 110, each lug having a first mounting hole 111. The propeller hub 200 is located at the interval between the two first lugs 110, and the propeller hub 200 has a first through hole 203 for the flapping shaft 310 to pass through. Thus, the structure is simple and easy to implement.

[0074] Of course, in other embodiments, the mounting base 100 may also adopt other structural forms. For example, the upper end face of the mounting base is provided with a mounting protrusion, the mounting protrusion is provided with a first mounting hole that passes through both sides thereon, the propeller hub is provided with a clearance hole corresponding to the mounting protrusion, the mounting protrusion extends into the clearance hole, the flapping shaft passes through the first mounting hole, and the two ends of the flapping shaft are respectively connected to the opposite side hole walls of the clearance hole.

[0075] Please see Figure 3 and Figure 7 Optionally, the first through hole 203 includes a middle section 205 and an end section 206, which are connected to the middle section 205. The diameter of the end section 206 is larger than that of the middle section 205, so that a stepped surface 207 is formed at the connection between the end section 206 and the middle section 205. One end of the swing sleeve 330 extends into the end section 206 and abuts against the stepped surface 207, while the other end of the swing sleeve 330 abuts against the end face of the elastic bearing 320. In this way, on the one hand, the stepped surface 207 and the end section 206 are used together to install and constrain the swing sleeve 330, which is simple and easy to implement. On the other hand, the swing sleeve 330 is used to constrain the axial movement of the elastic bearing 320, thereby improving the axial stability of the elastic bearing 320, which is simple and easy to assemble.

[0076] Optionally, one end of the swing sleeve 330 abuts against the stepped surface 207, and the other end of the swing sleeve 330 abuts against the end face of the bearing inner ring 322 to achieve axial constraint on the bearing inner ring 322. Of course, in other embodiments, the bearing inner ring 322 can also be mounted on the swing shaft 310 by fasteners such as screws, or the bearing inner ring 322 can be directly welded and fixed to the swing shaft 310.

[0077] In an embodiment where both the first mounting hole 111 and the elastic bearing 320 are provided in two, optionally, two through hole end sections 206 are provided, and the two through hole end sections 206 are respectively connected to the two ends of the through hole middle section 205.

[0078] Please see Figure 2 and Figure 3 Optionally, the swing hinge 300 also includes a locking nut 340, which is locked onto the end of the swing shaft 310 that passes through the first mounting hole 111. Specifically, after passing through the first mounting hole 111, the end of the swing shaft 310 is locked by the locking nut 340, and the end of the swing shaft 310 has a radial opening to allow a cotter pin to pass through the locking nut 340 for anti-loosening purposes. It should be noted that in the embodiment where the swing shaft 310 has a shaft end section 312 and the outer peripheral surface of the shaft end section 312 is a prismatic surface, the shaft end section 312 has a threaded post on the end face extending out of the first mounting hole 111, which is used for locking the locking nut 340. In this way, the locking nut 340 and the swing shaft sleeve 330 cooperate with each other to constrain the axial movement of the bearing inner ring 322, thereby improving the axial stability of the elastic bearing 320.

[0079] Please see Figure 6 Optionally, a bearing key 324 is provided on the outer circumferential surface of the bearing outer ring 321, and a notch 112 is provided on the wall surface of the first mounting hole 111 corresponding to the bearing key. The bearing key 324 is inserted into the notch 112 along the axial direction of the first mounting hole 111. Specifically, the bearing key 324 can be integrally formed from the bearing outer ring 321, or the two can be assembled into one piece by welding or other methods after being formed separately. In this way, the bearing key 324 and the notch 112 cooperate with each other to transmit the torque of the swing shaft 310 to the mounting base 100, and can prevent relative sliding between the elastic bearing 320 and the mounting base 100 in the axial direction. Of course, in other embodiments, the bearing key 324 and the notch 112 may not be provided. For example, the bearing outer ring 321 is fastened to the mounting base 100 by screws, or the bearing outer ring 321 is directly welded to the mounting base 100.

[0080] The notch 112 extends axially and may penetrate only one end face of the first lug 110 or both end faces of the first lug 110. In this embodiment, the notch 112 only penetrates the end face of the first lug 110 away from the midpoint of the hub 200. In this case, the groove sidewall of the notch 112 near the midpoint of the hub 200 can provide additional constraint on the bearing outer ring 321 to limit the movement of the bearing outer ring 321 toward the midpoint of the hub 200.

[0081] It is understood that the elastic bearing 320 is not limited to being mounted on the mounting base 100, but can also be mounted on the propeller hub 200. For example, please refer to Figure 8 In another embodiment, the elastic bearing 320 is mounted on the propeller hub 200, and the flapping hinge 300 also includes a flapping shaft 310, which is fixedly connected to the mounting base 100. The propeller hub 200 is rotatably connected to the flapping shaft 310 via the elastic bearing 320. In this way, the path for the flapping torque to be transmitted from the propeller hub 200 to the bearing elastic body 323 is shorter, which is beneficial for the elastic bearing 320 to unload the flapping torque.

[0082] The waving shaft 310 is fixedly connected to the mounting base 100, meaning that the waving shaft 310 is relatively fixedly connected to the mounting base 100, and the waving shaft 310 cannot rotate relative to the mounting base 100 around its own axis. At this time, the waving shaft 310 and the mounting base 100 can be either detachably connected or fixed together by means of welding or other methods.

[0083] Please see Figure 8 In another embodiment, optionally, the propeller hub 200 is provided with a third mounting hole 208, and the elastic bearing 320 includes an outer bearing ring 321, an inner bearing ring 322, and a bearing elastic body 323. The bearing elastic body 323 is disposed between the outer bearing ring 321 and the inner bearing ring 322. The outer bearing ring 321 is connected to the hole wall of the third mounting hole 208. The swinging torque of the propeller hub 200 can be transmitted to the outer bearing ring 321 through the hole wall of the third mounting hole 208, and then to the bearing elastic body 323 through the outer bearing ring 321. The inner bearing ring 322 is fixedly sleeved on the swinging shaft 310, and the inner bearing ring 322 is relatively fixedly connected to the mounting base 100 through the swinging shaft 310.

[0084] In another embodiment, the outer peripheral surface of the bearing outer ring 321 is fixedly connected to the hole wall of the third mounting hole 208. This connection can be achieved by configuring the outer peripheral surface of the bearing outer ring 321 and the hole wall of the third mounting hole 208 as a matching prism or elliptical cylindrical surface, or as an interference fit cylindrical surface. Alternatively, the bearing outer ring 321 can be welded and fixed to the hole wall of the third mounting hole 208.

[0085] In another embodiment, the bearing inner ring 322 is fixedly sleeved on the swing shaft 310. The inner circumferential surface of the bearing inner ring 322 and the outer circumferential surface of the swing shaft 310 may be configured as a matching prism surface or elliptical cylindrical surface, or configured as an interference fit cylindrical surface. Alternatively, the swing shaft 310 may be welded and fixed to the bearing inner ring 322.

[0086] Please see Figure 8 In another embodiment, the mounting base 100 may be provided with two first lugs 110, each with a first mounting hole 111. The two ends of the waving shaft 310 are respectively fixedly connected to the two first mounting holes 111. The hub 200 is provided with a first through hole 203 for the waving shaft 310 to pass through, and a third mounting hole 208 is formed at both ends of the first through hole 203. The waving shaft 310 is fixedly connected to the mounting base 100. The outer peripheral surface of the end of the waving shaft 310 and the wall surface of the first mounting hole 111 may be configured as a matching prism or elliptical cylindrical surface, or as an interference-fit cylindrical surface. Alternatively, the end of the waving shaft 310 may be welded and fixed to the wall surface of the first mounting hole 111.

[0087] Please see Figure 2 Optionally, the end of the hub 200 is provided with two mounting positions 201 for mounting the blades 700. The two mounting positions 201 are distributed along a first direction. A reference straight line is obtained by rotating the first direction along the rotation direction of the hub 200 by an included angle θ. The axis of the flapping hinge 300 is parallel to the reference straight line. The included angle θ ranges from 10° to 80°.

[0088] For easier understanding, please refer to Figure 2 The axis MN of the flapping hinge 300 can be considered as being composed of a first ray OM and a second ray ON, respectively located on both sides of the rotation axis at the output end of the power unit. Simultaneously, the first direction PQ can be considered as being composed of a third ray OP and a fourth ray OQ, respectively located on both sides of the rotation axis at the output end of the power unit. The first ray OM is close to the third ray OP and one of its mounting positions 201, while the second ray ON is close to the fourth ray OQ and the other mounting position 201. The angle between the first ray OM and the third ray OP is θ, and the first ray OM is located in front of the third ray OP in the rotation direction of the rotor hub 200. Similarly, the angle between the second ray ON and the fourth ray OQ is also θ, and the second ray ON is located in front of the fourth ray OQ in the rotation direction of the rotor hub 200. That is, when the rotor hub 200 rotates, the first ray OM will pass through the same reference point in both of their directions of travel before the third ray OP, and the second ray ON will pass through the same reference point in both of their directions of travel before the fourth ray OQ.

[0089] That is, when the axis of the flapping hinge 300 and the first direction are projected onto the rotation plane of the hub 200, these two projected lines intersect at an acute angle. This is equivalent to deflecting the flapping hinge 300 by an acute angle based on the conventional flapping hinge 300 in the prior art. Thus, by designing the flapping hinge 300 to be non-perpendicular to the first direction, the propeller can change the pitch angle of the blade 700 while performing flapping motion. Furthermore, since the end of the flapping hinge 300 is located in front of its adjacent mounting position 201, the preceding blade 700 (reference...) Figure 2 The leftmost blade (700) is propelled upwards by a greater aerodynamic force, while the trailing blade (700, reference) Figure 2 When the rightmost blade 700 (center-right) flaps downwards due to a smaller aerodynamic force, the upward flapping motion of the advancing blade 700 reduces its pitch angle and angle of attack. The decrease in angle of attack reduces the aerodynamic force on the advancing blade 700, thus suppressing its upward flapping motion and reducing its amplitude. Similarly, the downward flapping motion of the retreating blade 700 increases its pitch angle and angle of attack. The increased angle of attack increases the aerodynamic force on the retreating blade 700, suppressing its downward flapping motion and reducing its amplitude.

[0090] In this embodiment, the included angle θ is defined as the flapping adjustment coefficient. The included angle θ is directly proportional to the flapping adjustment coefficient; that is, the larger the included angle θ, the larger the flapping adjustment coefficient, and vice versa. It can be understood that the larger the included angle θ, the greater the change in pitch angle caused by the flapping motion; the smaller the included angle, the smaller the change in pitch angle caused by the flapping motion. Therefore, in order for the flapping hinge 300 to simultaneously achieve flapping and pitch-changing dual-degree-of-freedom motion, and to maintain a good balance between the two, the flapping adjustment coefficient, i.e., the included angle θ, cannot be set too large or too small. Preferably, the included angle θ ranges from 30° to 45°, for example, values ​​of 30°, 31°, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44° or 45°. In this way, the change in pitch angle caused by the flapping action of the propeller blade 700 is sufficient to curb further flapping of the propeller blade 700, and will not cause significant changes in the aerodynamic force on the propeller blade 700 that would affect flight control.

[0091] In this way, the pitch angle of the blade 700 can be adjusted without setting a pitch hinge. The adaptive adjustment of the pitch angle can suppress and reduce the flapping amplitude of the blade 700. On the one hand, the propeller can be set as close as possible to the aircraft fuselage during the design stage, thereby reducing the cruise drag caused by the propeller. On the other hand, it can reduce the periodic oscillation caused by the flapping of the blade 700, improve the life of the hub 200, and enhance flight stability and safety.

[0092] In this embodiment, by retaining the flapping hinge 300 and saving the oscillating hinge and pitch hinge, the structural complexity and weight of the propeller can be significantly reduced, as well as the manufacturing cost and subsequent maintenance cost of the propeller. On this basis, the root bending moment unloading function caused by uneven aerodynamic loads of the eVTOL propeller can be met.

[0093] Secondly, during the flapping and pitch-changing processes of the propeller blade 700, aerodynamic, elastic, and inertial forces are coupled together, stabilizing the propeller's vibrational and divergent aeroelastic response. Furthermore, this significantly reduces the flapping range of the propeller blade 700, decreasing the additional drag caused by flapping during forward flight and improving flight endurance and performance. Moreover, the reduced flapping amplitude simultaneously reduces the risk of damage to the aircraft caused by excessive deformation of the propeller blade 700 striking the aircraft structure due to aeroelastic instability or lag during maneuvers.

[0094] Please see Figures 1 to 3 In one embodiment, the propeller hub assembly further includes a damping structure 400, which includes an elastic damping member 410. The elastic damping member 410 has damping portions 401 respectively disposed on both sides of the axis of the swing hinge 300. The elastic damping member 410 is connected between the propeller hub 200 and the mounting base 100 so that when the propeller hub 200 swings, at least one damping portion 401 of the elastic damping member 410 is compressed and then reacts to the propeller hub 200.

[0095] It should be noted that the damping structure 400 of this embodiment can be applied to products where two blades 700 share a flapping hinge 300, or to products where two (or more) blades 700 are each equipped with their own flapping hinge 300. Similarly, the damping structure 400 of this embodiment can be applied to any product where the included angle θ ranges from 10° to 80°. That is, the damping structure 400 of this embodiment does not necessarily rely on other technical solutions for implementation.

[0096] Specifically, by incorporating an elastic damping element 410, when the blade 700 flaps, the rotor hub 200 compresses at least one damping portion 401 of the elastic damping element 410. The damping portion 401 undergoes elastic deformation and provides a reaction force, thus providing damping during the flapping of the blade 700. In this way, the damping structure 400 is used for shock absorption and buffering throughout the entire flapping motion from zero to limit positions, thereby ensuring the torsional stiffness of the blade 700 during its up-and-down flapping, improving the linearity of the flapping motion, reducing the amount of speed adjustment variation in flight control, and facilitating aircraft handling.

[0097] Please see Figure 3 and Figure 4 Optionally, the damping structure 400 further includes a damping shaft 420, an elastic damping element 410 which is tubular and surrounds the outer periphery of the damping shaft 420, an inner ring of the elastic damping element 410 which is fixedly sleeved on the damping shaft 420, an outer ring of the elastic damping element 410 which is fixedly connected to the propeller hub 200, and an axis of the damping shaft 420 which intersects with the axis of the flapping hinge 300. Specifically, since the damping shaft 420 is fixed relative to the mounting base 100, when the blade 700 swings around the axis of the swing hinge 300, the hub 200 drives the elastic damping element 410 to rotate around the axis of the swing hinge 300. The gap between the hub 200 and the damping shaft 420 changes, causing partial deformation of the damping portions 401 on both sides of the axis of the swing hinge 300. Therefore, both sides of the damping portions 401 can provide a reaction force to the hub 200 to suppress the swinging motion of the hub 200 and the blade 700 on it. In this way, the elastic damping element 410 is installed between the mounting base 100 and the hub 200 through the damping shaft 420, and the damping portion 401 can deform when the blade 700 swings. The structure is simple and easy to implement.

[0098] It should be noted that the damping part 401 is a hypothetical concept defined for ease of understanding of the scheme and does not refer to a specific part structure. For example, please refer to... Figures 3 to 5 In this embodiment, the elastic damping member 410 includes a tubular damping elastic body 413. The damping elastic body 413 extends axially along the damping shaft 420, and the region of the damping elastic body 413 surrounding the swing hinge 300 extends continuously from one side of the swing hinge 300's axis to the other side. In this case, the damping elastic body 413 can be considered to have two regions opposite each other axially along the damping shaft 420, and both regions can be defined as damping portions 401. Therefore, in this embodiment, it does not mean that two separately arranged damping portions 401 constitute two independent elastic damping members 410, but rather that different regions on one elastic damping member 410 can all be used as damping portions 401 under compressive deformation.

[0099] Of course, in other embodiments, the damping shaft 420 may not be provided. For example, the damping structure 400 includes two elastic damping elements 410 arranged in a split structure. The elastic damping elements 410 are configured as elastic damping blocks. The two elastic damping blocks are respectively arranged on both sides of the axis of the flapping hinge 300. The center of the rotor hub 200 is provided with a seat hole. The mounting seat 100 passes through the seat hole. The wall of the seat hole is provided with a mounting groove corresponding to the elastic damping block. The two elastic damping blocks are respectively installed in the two mounting grooves, and the part of the elastic damping block exposed outside the groove of the mounting groove abuts against the part of the mounting seat 100 located in the seat hole.

[0100] Please see Figure 2 and Figure 3 Optionally, the axis of the damping shaft 420 is perpendicular to the axis of the flapping hinge 300. In this way, under the condition of equal flapping amplitude, the elastic deformation of the elastic damping element 410 can reach its maximum, thereby maximizing the damping force of the damping structure 400 acting on the rotor hub 200. Of course, in other embodiments, the axis of the damping shaft 420 may intersect but not be perpendicular to the axis of the flapping hinge 300.

[0101] Optionally, the angle between the axis of the damping shaft 420 and the first direction ranges from 45° to 60°, for example, values ​​of 45°, 46°, 47°, 48°, 49°, 50°, 51°, 52°, 53°, 54°, 55°, 56°, 57°, 58°, 59°, or 60°. This allows for changes in the pitch angle caused by the flapping motion of the blade 700, suppressing further flapping of the blade 700, while preventing significant changes in the aerodynamic forces acting on the blade 700 that could affect flight control.

[0102] Optionally, the mounting base 100 has two opposing second lugs 120, and the two ends of the damping shaft 420 are respectively connected to the two second lugs 120. The rotor hub 200 is located at the interval between the two second lugs 120. Alternatively, a second mounting hole 121 can be provided on the second lug 120, and the end of the damping shaft 420 can be inserted and mounted in the second mounting hole 121. This results in a simple structure that is easy to implement. Of course, in other embodiments, the second lugs 120 may not be provided.

[0103] Please see Figure 1In one embodiment, the mounting base 100 is further provided with two opposing first lugs 110, and the two ends of the flaring shaft 310 are respectively connected to the two first lugs 110. In this embodiment, the first lugs 110 and the second lugs 120 together define a mounting space 101, and the propeller hub 200 is at least partially disposed in the mounting space 101. Specifically, the upper side of the mounting base 100 is provided with the first lugs 110 and the second lugs 120 protruding upwards. The two first lugs 110 and the two second lugs 120 are alternately distributed along the axis of the mounting base 100 (i.e., the rotation axis of the propeller). The distribution direction of the two first lugs 110 intersects with the first direction, and the distribution direction of the two second lugs 120 also intersects with the first direction.

[0104] Please see Figure 1 and Figure 4 Optionally, the rotor hub assembly also includes a limiting member 500 disposed on the bottom surface of the mounting space 101. The limiting member 500 has a limiting surface 501, and the lower end surface of the rotor hub 200 can abut against the limiting surface 501 to limit the swing limit position of the rotor hub 200. Specifically, the limiting member 500 is made of an elastic material. In this way, the limiting member 500 can limit the swing angle of the rotor blade 700, while avoiding rigid collisions between the rotor blade 700 and other components (such as the mounting base 100), thereby increasing flight safety. It is worth mentioning that the damping shaft 420 can also limit the swing angle of the rotor blade 700. That is, the damping shaft 420 and the limiting member 500 cooperate to limit the swing amplitude of the propeller in the aircraft's cruise mode, thereby reducing flight drag. Optionally, the limiting member 500 is fastened to the propeller hub 200 by screws; there are two limiting surfaces 501, which are distributed at intervals along the first direction and located on both sides of the axis of the flapping hinge 300.

[0105] Specifically, when the propeller hub 200 flaps, its lower end face gradually approaches the limiting surface 501. Due to the combined action of the elastic damping element 410 and the damping shaft 420, the lower end face of the propeller hub 200 will not contact the limiting surface 501 during uniform flapping. However, when the propeller encounters a gust of wind or other sudden load changes, the propeller hub 200 may experience a certain acceleration, leading to an increased flapping amplitude. In this case, the lower end face of the propeller hub 200 will approach and contact the limiting surface 501, thereby achieving mechanical protection and improving flight stability and safety.

[0106] Of course, in other embodiments, the limiting member 500 and the limiting surface 501 may not be provided. For example, a wave limiter composed of a wave limiting bolt and an elastic filling material may be provided on the mounting base 100, and the elastic material of the wave limiter may be used for buffering, shock absorption and limiting.

[0107] The elastic damping element 410 can have various structural forms; for example, please refer to [link to relevant documentation]. Figure 3In one embodiment, the elastic damping element 410 includes an outer ring sleeve 411, an inner ring sleeve 412, and a damping elastic body 413. The damping elastic body 413 is disposed between the inner ring sleeve 412 and the outer ring sleeve 411. The outer ring sleeve 411 is mounted on the propeller hub 200, and the inner ring sleeve 412 is mounted on the damping shaft 420. Thus, the structure is simple and easy to implement.

[0108] The material of the damping elastomer 413 is not specifically limited, and may include, but is not limited to, rubber or silicone. The damping properties of rubber help absorb high-frequency vibrations. The outer ring 411 and the inner ring 412 may be made of metal, plastic or composite materials, such as steel. This application does not specifically limit the materials used.

[0109] Please see Figure 3 Optionally, the propeller hub 200 is provided with a second through hole 204, and the damping structure 400 is installed in the second through hole 204. The outer ring sleeve 411 is connected to the hole wall of the second through hole 204 by a damping fastener. Specifically, the damping fastener can be a screw or a rivet, for example, a screw whose tip can penetrate from the outer surface of the propeller hub 200 and extend into the second through hole 204 to be threadedly connected or abutted against the outer ring sleeve 411. In this way, the structure is simple and easy to implement. In the embodiment where the axis of the flapping shaft 310 is perpendicular to the axis of the damping shaft 420, the axis of the first through hole 203 and the axis of the second through hole 204 are set perpendicularly. Of course, in other embodiments, the outer ring sleeve 411 can also be directly welded to the hole wall of the second through hole 204.

[0110] Please see Figures 3 to 5 In one embodiment, the flapping hinge 300 includes a flapping shaft 310, and the elastic damping member 410 is provided with a clearance hole 414. The flapping shaft 310 has a shaft middle section 311 passing through the clearance hole 414. The outer diameter of the shaft middle section 311 is smaller than the outer diameter of the damping shaft 420, that is, the outer diameter of the shaft middle section 311 is smaller than the inner diameter of the inner ring sleeve 412. The clearance hole 414 passes through the outer ring sleeve 411, the damping elastic body 413 and the inner ring sleeve 412. When the propeller hub 200 flaps, the damping elastic body 413 undergoes elastic deformation along the circumferential direction of the clearance hole 414 and reacts on the propeller hub 200.

[0111] Specifically, please refer to Figure 5 , Figure 5 The diagram illustrates two positions of the propeller hub 200 in the flapping direction. The first position (initial position) is shown with the cross-section line. The bold dashed box represents the second position after the propeller hub 200 has rotated a certain angle (acute angle) around the axis of the flapping axis 310 from its initial position along the flapping direction shown in the diagram. The line containing the axis of the damping axis 420 is defined as the X-axis, and the line containing the axis of the flapping axis 310 is defined as the Y-axis. The Z-axis, perpendicular to both the X-axis and Y-axis, is... Figure 5Extending vertically within; based on this, define Figure 5 The four quadrants defined by the X-axis and Z-axis are the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant. The first quadrant is located in the upper right corner of the figure, the second quadrant is located in the upper left corner of the figure, the third quadrant is located in the lower left corner of the figure, and the fourth quadrant is located in the lower right corner of the figure.

[0112] After comparing and analyzing the relative positions of the rotor hub 200 and the damping shaft 420 in the first and second positions, it can be seen that in the second position, the distance between the upper sidewall of the second through hole 204 in the first quadrant and the damping shaft 420 decreases, causing the damping elastic body 413 in the first quadrant to be compressed; the distance between the upper sidewall of the second through hole 204 in the second quadrant and the damping shaft 420 increases, causing the damping elastic body 413 in the second quadrant to be stretched; the distance between the lower sidewall of the second through hole 204 in the third quadrant and the damping shaft 420 decreases, causing the damping elastic body 413 in the third quadrant to be compressed; and the distance between the lower sidewall of the second through hole 204 in the fourth quadrant and the damping shaft 420 increases, causing the damping elastic body 413 in the second quadrant to be stretched. It is understandable that the damping elastic bodies 413 in these four quadrants will all undergo elastic deformation due to the flapping motion of the propeller hub 200, and the elastic damping force generated by the elastic deformation will all react on the propeller hub 200 to suppress the flapping motion of the propeller hub 200. In this embodiment, through ingenious structural design, when the propeller hub 200 flaps, the damping elastic body 413 can undergo elastic deformation along the circumferential direction of the relief hole 414 and react on the propeller hub 200. That is, different areas of the damping elastic body 413 can all undergo elastic deformation and play a flapping damping role, thereby achieving a better damping effect with a smaller structural volume. In other words, it is possible to make the elastic damping component 410 more compact while achieving the same damping effect.

[0113] It should be noted that during assembly, the elastic damping component 410 is installed first, followed by the swing shaft 310. In the embodiment where the outer peripheral surface of the end section 312 of the swing shaft 310 is a prismatic surface, the outer peripheral surface of the middle section 311 can be a prismatic or cylindrical surface, as long as the middle section 311 maintains a clearance fit with the first through hole 203 and the clearance hole 414. For example, the two ends of the shaft middle section 311 can be connected to a shaft end section 312. The outer circumferential surface of the shaft middle section 311 is cylindrical, and the outer circumferential surfaces of the two shaft end sections 312 are prismatic. The inscribed circle diameter of the prismatic surface of the shaft end section 312 is greater than or equal to the cylindrical surface diameter of the shaft middle section 311. In this case, the minimum diameter of the first through hole 203 and the clearance hole 414 is greater than the circumscribed circle diameter of the prismatic surface of the shaft end section 312, so that one end of the swing shaft 310 can be inserted into one end of the first through hole 203 and exit from the other end of the first through hole 203. This facilitates the manufacturing, forming, and installation of the elastic damping element 410 and the swing shaft 310.

[0114] Specifically, please refer to Figure 7 In this embodiment, the diameter of the through hole end section 206 is larger than that of the through hole middle section 205 to form a stepped surface 207. The maximum diameters of the shaft middle section 311 and the shaft end section 312 are both smaller than that of the through hole middle section 205. The inner end face of the swing bushing 330 abuts against the stepped surface 207. The inner circumferential surface of the swing bushing 330 is a hexagonal prism surface and is adapted to fit the shaft end section 312. The outer circumferential surface of the swing bushing 330 is a cylindrical surface and is interference-fitted with the through hole end section 206.

[0115] Please see Figure 3 Optionally, the damping elastomer 413 has a concave curved surface 415 on its end face away from the axis of the flapping hinge 300, with the concave curved surface 415 recessed towards the axis of the flapping hinge 300. Thus, since the end face of the damping elastomer 413 is not the surface directly bearing the pressure of the rotor hub 200 and the damping shaft 420 (i.e., a non-pressure-bearing surface), designing this non-pressure-bearing surface to be concave inwards can reduce the risk of cracking of the damping elastomer 413 and improve its service life. Of course, in other embodiments, the concave curved surface 415 may be recessed along the axis away from the flapping hinge 300, or the concave curved surface 415 may not be provided.

[0116] It is worth mentioning that in this embodiment, the damping shaft 420 passes through the second through hole 204 of the propeller hub 200, and the propeller hub 200 achieves an integrated structural design, which is simpler and lighter than traditional mechanical hydraulic dampers. For example, it can save the holding device of traditional dampers, thereby simplifying the structure of the propeller hub assembly and facilitating the lightweight design of the propeller hub assembly.

[0117] Please see Figure 2 and Figure 3Optionally, the mounting base 100 is provided with two opposing second lugs 120, and the two ends of the damping shaft 420 are respectively connected to the two second lugs 120. The damping structure 400 also includes two damping bushings 430 sleeved on the damping shaft 420. The two damping bushings 430 are respectively disposed on the axial sides of the elastic damping member 410. One end of the damping bushing 430 abuts against the end face of the inner ring sleeve 412, and the other end of the damping bushing 430 abuts against the end face of the second lug 120. Specifically, during assembly, the elastic damping element 410 is first inserted into the second through hole 204, and the outer ring sleeve 411 of the elastic damping element 410 is restrained by damping fasteners. Then, two damping bushings 430 are respectively installed at both ends of the second through hole 204. Next, one end of the damping shaft 420 is sequentially passed through one of the second mounting holes 121, one of the damping bushings 430, the elastic damping element 410, the other damping bushing 430, and the other second mounting hole 121. Then, the two ends of the damping shaft 420 are respectively connected to the two second mounting holes 121. In this way, the axial movement of the inner ring sleeve 412 is effectively restricted by the cooperation of the two damping bushings 430, thereby allowing the elastic damping element 410 to be stably and reliably installed on the propeller hub 200 and the damping shaft 420. Furthermore, the result is simple and easy to assemble. Of course, in other embodiments, the damping bushings 430 may not be provided.

[0118] The connection between the end of the damping shaft 420 and the second mounting hole 121 can be varied. For example, the damping shaft 420 can be detachably connected to the second mounting hole 121. Alternatively, a pin can be inserted into the portion of the damping shaft 420 extending out of the second mounting hole 121 to restrict axial movement. Another option is that the portion of the damping shaft 420 extending out of the second mounting hole 121 has external threads and is threadedly connected to a nut. Of course, the damping shaft 420 can also be directly welded to the edge of the second mounting hole 121.

[0119] Please see Figure 1 and Figure 4 Optionally, the propeller hub assembly further includes at least two counterweight structures 600 disposed on the propeller hub 200, with the at least two counterweight structures 600 respectively disposed on both sides of the axis of the flapping hinge 300. Specifically, at least two counterweight structures 600 may be disposed at opposite ends of the propeller hub 200 in the first direction. By providing counterweight structures 600 at both ends of the propeller hub 200, the balance of the propeller can be quickly adjusted by increasing or decreasing the number of counterweight structures 600 or by replacing the counterweight structures 600.

[0120] Please see Figure 4Optionally, the counterweight structure 600 includes a counterweight block 610 and a counterweight fastener 620, with the counterweight block 610 mounted on the upper surface of the propeller hub 200 via the counterweight fastener 620. The counterweight fastener 620 can be a screw. This design is simple and allows for easy adjustment of the weight of the counterweight structure 600. Alternatively, in other embodiments, the counterweight fastener 620 may be omitted, and the counterweight block 610 may be directly bonded to the propeller hub 200.

[0121] The counterweight structure 600 can be placed at the outermost end of the propeller hub 200, that is, the area closest to the mounting position 201, to maximize the lever arm of the counterweight structure 600. This allows for a better counterweight effect with a smaller weight of the counterweight structure 600, which in turn helps to achieve a lightweight design of the propeller hub assembly.

[0122] The present invention also proposes a propeller comprising two blades and the aforementioned hub assembly. The specific structure of the hub assembly is as described in the above embodiments. Since this propeller adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here. Specifically, the two blades are disposed at both ends of the hub. The ends of the hub are provided with two mounting positions, and both the two mounting positions and the two blades are distributed along a first direction. The blades are connected to the mounting positions.

[0123] This invention also proposes an aircraft, such as an electric vertical takeoff and landing (EVTOL) aircraft. The aircraft includes a fuselage, a power unit, and the aforementioned propeller. The specific structure of the propeller is as described in the above embodiments. Since this aircraft adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here. Specifically, the power unit is located on the fuselage and drives the propeller. The output end of the power unit extends out of the fuselage and is connected to the mounting base of the propeller hub.

[0124] Optionally, the aircraft includes a fixed wing and multiple rotors, the multiple rotors including a lifting rotor, the lifting rotor including a power unit and the aforementioned propeller. The power unit may be an electric motor or an engine, etc.

[0125] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A propeller hub assembly, characterized in that, The propeller hub assembly includes: Mounting bracket, drive connection to the output end of the power unit; The hub is used to mount the propeller blades; A flapping hinge, the flapping hinge including a resilient bearing, the rotor hub being rotatably connected to the mounting base via the resilient bearing; The elastic bearing is mounted on the mounting base, and the flapping hinge also includes a flapping shaft. The flapping shaft is rotatably connected to the mounting base through the elastic bearing, and the flapping shaft is fixedly connected to the propeller hub so that the flapping torque of the propeller hub can be transmitted to the elastic bearing through the flapping shaft. The propeller hub is provided with a first through hole, and the flapping hinge further includes a flapping bushing. The flapping shaft has a shaft end section corresponding to the flapping bushing. The outer peripheral surface of the flapping bushing is connected to the hole wall of the first through hole, and the inner peripheral surface of the flapping bushing is connected to the outer peripheral surface of the shaft end section. The flapping torque of the propeller hub can be transmitted to the shaft end section through the flapping bushing. The mounting base is provided with a first mounting hole. The elastic bearing includes an outer bearing ring, an inner bearing ring, and a bearing elastic body. The bearing elastic body is disposed between the outer bearing ring and the inner bearing ring. The outer bearing ring is fixedly connected to the wall surface of the first mounting hole. The inner bearing ring is sleeved on the shaft end section. The swinging torque on the shaft end section can be transmitted to the inner bearing ring and then to the bearing elastic body through the inner bearing ring.

2. The propeller hub assembly as claimed in claim 1, characterized in that, The inner circumferential surface of the swinging bushing and the outer circumferential surface of the shaft end section are configured as matching prism surfaces or elliptical cylindrical surfaces, or the inner circumferential surface of the swinging bushing and the outer circumferential surface of the shaft end section are configured as interference-fit cylindrical surfaces, so as to realize the transmission of swinging torque from the swinging bushing to the shaft end section. And / or, the outer peripheral surface of the waving bushing and the hole wall surface of the first through hole are configured as an interference fit cylindrical surface, or the outer peripheral surface of the waving bushing and the hole wall surface of the first through hole are configured as a matching prism surface or elliptical cylinder surface, so as to realize the transmission of waving torque from the propeller hub to the waving bushing.

3. The propeller hub assembly as described in claim 1, characterized in that, The first through hole includes a middle section and an end section of the through hole that connects to the middle section. The diameter of the end section of the through hole is larger than that of the middle section of the through hole, so as to form a stepped surface at the connection between the end section of the through hole and the middle section of the through hole. One end of the swinging bushing extends into the end section of the through hole and abuts against the stepped surface, and the other end of the swinging bushing abuts against the end face of the elastic bearing.

4. The propeller hub assembly as claimed in claim 1, characterized in that, The inner circumferential surface of the bearing inner ring and the outer circumferential surface of the shaft end section are configured as matching prismatic or elliptical cylindrical surfaces, or the inner circumferential surface of the bearing inner ring and the outer circumferential surface of the shaft end section are configured as interference-fit cylindrical surfaces to realize the transmission of swinging torque from the shaft end section to the bearing inner ring.

5. The propeller hub assembly as claimed in claim 1, characterized in that, The mounting base has two opposing first mounting holes for mounting the elastic bearing. The propeller hub is located at the interval between the two first mounting holes. The propeller hub has a first through hole for the swing shaft to pass through. The two ends of the swing shaft are respectively connected to the elastic bearings on the two first mounting holes.

6. The propeller hub assembly as claimed in claim 5, characterized in that, The outer peripheral surface of the elastic bearing is provided with a bearing key, and the wall of the first mounting hole is provided with a notch corresponding to the bearing key. The bearing key is inserted into the notch along the axial direction of the first mounting hole. And / or, the swing hinge further includes a locking nut that is locked onto the end of the swing shaft that passes through the first mounting hole.

7. The propeller hub assembly as described in any one of claims 1 to 6, characterized in that, The resilient bearing includes an outer bearing ring, an inner bearing ring, and a bearing elastomer, wherein the bearing elastomer is disposed between the outer bearing ring and the inner bearing ring; the outer circumferential surface and / or the inner circumferential surface of the bearing elastomer is configured as a frustoconical surface, and / or the bearing elastomer includes alternating layers of elastic layers and metal layers, wherein the elastic layers and the metal layers are integrally formed by layered vulcanization.

8. The propeller hub assembly as described in any one of claims 1 to 6, characterized in that, The propeller hub assembly further includes at least two counterweight structures disposed on the propeller hub, with the at least two counterweight structures respectively disposed on both sides of the axis of the flapping hinge; the counterweight structure includes a counterweight block and a counterweight fastener, and the counterweight block is mounted on the upper end surface of the propeller hub by the counterweight fastener.

9. A propeller, characterized in that, It includes two blades and a hub assembly as described in any one of claims 1 to 8, wherein the hub has two mounting positions at its end, and the two blades are respectively disposed in the two mounting positions.

10. An aircraft, characterized in that, It includes a body, a power unit, and a propeller as described in claim 9, wherein the power unit is disposed in the body and drives a mounting base connected to the propeller.

11. The aircraft as claimed in claim 10, characterized in that, The aircraft is configured as an electric vertical takeoff and landing (EVTOL) aircraft.

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