Rotor, power assembly and air vehicle

A propeller includes a blade. The blade includes a blade root, a blade tip disposed away from the blade root, a blade front surface, and a blade back surface. The blade also includes a front edge connecting a first side of each of the blade front surface and the blade back surface. The blade also includes a rear edge connecting a second side of each of the blade front surface and the blade back surface. The blade further includes a first suppression member formed by a portion of the front edge adjacent to the blade tip bending toward a first direction. The first direction is a direction from the front edge to the rear edge. The first suppression member is configured to suppress a spanwise air flow.

TECHNICAL FIELD

The present disclosure relates to a rotor (also referred to as a propeller), a power assembly (also referred to as a propulsion assembly), and an air vehicle (also referred to as an aircraft), which belong to the technical field of air vehicle.

BACKGROUND

The rotor/propeller is a key component of a rotorcraft, which may be configured to convert the rotation output from an electric motor or an engine to a propulsion force or lifting force to realize the ascending and descending, turning, and hovering, etc. Because of the structure and operation characteristics of the rotor/propeller, when it rotates, a blade having a predetermined thickness periodically sweep through the surrounding air medium, causing air micro-clusters to perform periodic unsteady movement, thereby generating thickness noise. At the meantime, the pressure field on the surface of the blade may change, thereby generating the negative load noise. The thickness noise and the negative load noise may combine together to become a major portion of the aircraft noise, which may contaminate the surrounding air space environment. Such noise may also propagate to the aircraft body of the aircraft, causing vibration of the aircraft body, which may seriously affect the flight safety of the aircraft.

SUMMARY

In accordance with an aspect of the present disclosure, there is provided a propeller including a blade. The blade includes a blade root, a blade tip disposed away from the blade root, a blade front surface, and a blade back surface. The blade also includes a front edge connecting a first side of each of the blade front surface and the blade back surface. The blade also includes a rear edge connecting a second side of each of the blade front surface and the blade back surface. The blade further includes a first suppression member formed by a portion of the front edge adjacent to the blade tip bending toward a first direction. The first direction is a direction from the front edge to the rear edge. The first suppression member is configured to suppress a spanwise air flow.

In accordance with an aspect of the present disclosure, there is provided a propulsion assembly. The propulsion assembly includes a driving member and a propeller. The propeller includes a blade including a blade root and a blade tip disposed away from the blade root. The propeller also includes a blade hub connected with an output shaft of the driving member. The blade also includes a blade front surface, a blade back surface, a front edge connecting a first side of each of the blade front surface and the blade back surface, and a rear edge connecting a second side of each of the blade front surface and the blade back surface. The blade further includes a first suppression member formed by a portion of the front edge adjacent to the blade tip bending toward a first direction. The first direction is a direction from the front edge to the rear edge. The first suppression member is configured to suppress a spanwise air flow.

In accordance with an aspect of the present disclosure, there is provided an aircraft. The aircraft includes an aircraft frame, an aircraft arm, and a propulsion assembly. An end of the aircraft arm is connected with the aircraft frame, the other end of the aircraft arm is connected with the propulsion assembly. The propulsion assembly includes a driving member and a propeller. The propeller includes a blade including a blade root and a blade tip disposed away from the blade root, and a blade hub connected with an output shaft of the driving member. The blade also includes a blade front surface, a blade back surface, a front edge connecting a first side of each of the blade front surface and the blade back surface, and a rear edge connecting a second side of each of the blade front surface and the blade back surface. The propeller further includes a first suppression member formed by a portion of the front edge adjacent to the blade tip bending toward a first direction. The first direction being a direction from the front edge to the rear edge. The first suppression member is configured to suppress a spanwise air flow.

DESCRIPTION OF MAJOR ELEMENT LABEL

DETAILED DESCRIPTION OF THE EMBODIMENTS

Next, some embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. When there is no obvious conflict, the embodiments and the features of the embodiments may be combined.

FIG. 1shows a structure of a blade according to an embodiment of the present disclosure.FIG. 2is a front view of the structure shown inFIG. 1.FIG. 3is a right view of the structure shown inFIG. 1.FIG. 4is a left view of the structure shown inFIG. 1.FIG. 5is a bottom view of the structure shown inFIG. 1.FIG. 6is a top view of the structure shown inFIG. 1.

As shown inFIG. 1-FIG. 6, the propeller of the present disclosure is included in a propulsion assembly, which may be a blade driven by an electric motor or an engine to rotate to generate a lifting force or a propulsion force. The blade may include a blade root110fixed onto a wheel hub and a blade tip120facing away from the blade root110. When the propeller operates, the blade rotates around a rotation center, thereby forming a propeller disk, to disturb the air flow to generate a lifting force or a propulsion force to cause the manned or unmanned aircraft to move, such as an airship or a rotor-based unmanned aerial vehicle. The blade of the present disclosure may be manufactured using any suitable material available in the current technologies, including, but not limited to, steel, aluminum alloy, plastics, carbon fiber, etc. During manufacturing, various processing techniques available in the current technologies may be used, such as molding, stamping, and forging.

The blade may include a blade front surface130and a blade back surface140, a front edge150connecting a side of each of the blade back surface140and the blade back surface140, and a rear edge160connecting another side of each of the blade front surface130and the blade back surface140. The blade back surface140is a side of the blade that faces upwardly during a flight of the aircraft. The blade front surface130is a side of the blade that faces downwardly (or faces the ground) during the flight of the aircraft.

A portion of the front edge150adjacent to the blade tip120may bend in a first direction to form a first suppression member180. The first suppression member180may be configured to suppress the spanwise flow. The first direction is a direction from the front edge150to the rear edge160. Specifically, inFIG. 2, the front edge150bends to the left to form the first suppression member180. The first suppression member180may cut the spanwise flow of the air on the blade when the blade rotates, thereby reducing the turbulence generated by the blade tip120and reducing the intensity of the turbulence at the tip blade120, thereby reducing the degree of changes in air pressure adjacent to the blade tip, and reducing the degree of periodically cutting the air flow by the blade having a predetermined thickness, and further reducing the rotation noise generated by the rotating blade of the propeller.

In some embodiments, the specific location of the first suppression member180may be configured based on the specific requirement on the overall noise of the aircraft and the aerodynamic efficiency. When configuring the location of the first suppression member180, two aspects may be considered: locations of the first suppression member180and the blade tip120, and a distance from the first suppression member180to the center of the propeller disk.

For example, as shown inFIG. 2, in one embodiment, the blade includes a central axis line (shown as a dotted line extending through the center of the blade). The front edge150and the rear edge160of the blade each include a tangent parallel with the central axis line (shown as solid lines located on the left side and right side of the blade, respectively). The first suppression member180and the blade tip120may be disposed between the two tangents. A person having ordinary skills in the art can appreciate, the locations of the first suppression member180and the blade tip120do not limit the propeller of the present disclosure. In some practical configurations, it is possible that only one of the first suppression member180and the blade tip120is disposed between the two tangents. By disposing the first suppression member180, the blade tip120, or both between the two tangents, the aerodynamic efficiency of the propeller is not substantially affected while the rotation noise of the propeller is reduced, thereby achieving a balance between an excellent flight performance and a relatively small noise of the propeller.

As another example, in another embodiment, a ratio between a distance from the first suppression member180to a center of the propeller disk formed by the rotating blade and a radius of the propeller may be 79.4%-88.8%, such that the first suppression member180may not substantially affect the aerodynamic efficiency of the propeller while reducing the noise of the propeller.

It can be understood that the above two embodiments may be combined, such that while the rotation noise of the propeller is reduced, the aerodynamic efficiency of the propeller can be maintained to be substantially consistent with that of a typical rectangular propeller. The rectangular propeller is a propeller in which the blade tip120has a rectangular shape.

Referring toFIG. 1andFIG. 2, in some embodiments, a portion of the rear edge160adjacent to the blade tip120also bends in the first direction to form a second suppression member190configured to suppress the spanwise air flow. Specifically, as shown inFIG. 2, a portion of the rear edge160adjacent to the blade tip120bends to the left to form the second suppression member190. Similarly, when configuring the location of the second suppression member190, as in configuring the first suppression member180, the following factors may be considered: a degree of bending of the second suppression member190and the blade tip120, and a distance from the second suppression member190to the center of the propeller disk. For example, in some embodiments, the second suppression member190may be located between two tangents that are parallel with the central axis line, thereby achieving a balance between reducing the noise of the propeller and maintaining the aerodynamic efficiency of the propeller to be substantially the same as that of a typical rectangular propeller.

In some embodiments, as shown inFIG. 3andFIG. 4, the blade back surface140and the blade front surface130may be configured as curved surfaces. The trend of the curve may be: when the blade is in an overall horizontal state, the location of the front edge150is lower than the location of the rear edge160. By configuring the blade back surface140and the blade front surface130of the blade as curved surfaces, i.e., by configuring the surfaces of the blade to have a smooth transition, such that there is no sudden twist portion in the blade. As a result, the stress in the blade is relatively small, the strength is relatively high, which makes it not easy to be fractured, and the reliability is relatively high.

Referring toFIG. 3andFIG. 4, the thickness of the blade may gradually reduce from the blade root110to the blade tip120, making the end of the blade farthest from the center of the propeller disk to be the thinnest part of the blade, which can reduce the resistance of the air and improve the flight performance of the propeller.

In some embodiments, as shown inFIG. 1andFIG. 2, the front edge150may be provided with an arched portion having a curved surface shape. The arched portion may be connected with the remaining portions of the front edge150in a smooth transition. Specifically,FIG. 2shows that the arched portion of the blade is disposed at a location adjacent to the blade root110and the arched portion faces to the right.

In the propeller of the present disclosure, by forming the first suppression member180through bending the portion of the front edge150adjacent to the blade tip120toward the rear edge160, the spanwise air flow on the blade may be cut, thereby reducing the formation of the blade tip turbulence or reducing the intensity of the blade tip turbulence. As a result, the rotation noise of the propeller in the rotation process may be reduced, and the safety of the manned or unmanned aircraft (e.g., UAV or airship) may be enhanced.

FIG. 7schematically illustrates the locations of the cross sections of the blade.FIG. 8is a cross-sectional view along the A-A line of the structure shown inFIG. 7.FIG. 9is a cross-sectional view along the B-B line of the structure shown inFIG. 7.FIG. 10is a cross-sectional view along the C-C line of the structure shown inFIG. 7.FIG. 11is a cross-sectional view along the D-D line of the structure shown inFIG. 7.FIG. 12is a cross-sectional view along the E-E line of the structure shown inFIG. 7.FIG. 13is a cross-sectional view along the F-F line of the structure shown inFIG. 7.FIG. 14is a cross-sectional view along the G-G line of the structure shown inFIG. 7.

As shown inFIG. 7-FIG. 13, the present disclosure provides an embodiment that has been improved in size suitable for rotor-based unmanned aerial vehicle. A person having ordinary skills in the art can directly or after simple modification, apply the embodiments to other manned or unmanned aircrafts.

Specifically, in this embodiment, the sizes of the seven cross sections of the blade of the rotor-based unmanned aerial vehicle are improved. The improvement in the sizes at the C-C cross section, D-D cross section, and E-E cross section can bring great advantages:

At a location about 79.4% from the center of the propeller disk, i.e., at the C-C cross section that has a distance of H3from the center of the propeller disk as shown inFIG. 7, the chord length L3of the blade, as shown inFIG. 10, is about 16.39 mm±5 mm, the angle of attack α3is about 12.94°±2.5°. The chord length refers to, at the cross section, a horizontal distance between a leftmost end point of the front edge150at the cross section and a rightmost end point of the rear edge160at the cross section. The angle of attack is an angle between a line connecting the leftmost end point of the front edge150at the cross section and the rightmost end point of the rear edge160at the cross section and the horizontal direction, or, the angle of attack can be understood as an angle between the chord wing of the blade and the incoming direction of the air flow.

At a location about 84.1% from the center of the propeller disk, i.e., at the D-D cross section that has a distance of H4from the center of the propeller disk as shown inFIG. 7, the chord length L4of the blade as shown inFIG. 11is about 15.05 mm±5 mm, the angle of attack α4is about 11.55°±2.5°.

At a location about 88.8% from the center of the propeller disk, i.e., at the E-E cross section that has a distance of H5from the center of the propeller disk as shown inFIG. 7, the chord length L5of the blade as shown inFIG. 12is about 11.42 mm±5 mm, the angle of attack α5is about 10.69°±2.5°.

In this embodiment, by setting the chord lengths and the angles of attack at the three cross sections of the blade, the rotation noise generated by the propeller during the rotation process can be reduced, and the safety of the aircraft can be enhanced. In addition, the aerodynamic efficiency of the aircraft is not affected.

On the basis of the above embodiments, improvements may be made for the chord lengths and angles of attack at the A-A cross section, B-B cross section, F-F cross section, and G-G cross section, thereby further reducing the rotation noise generated by the propeller during the rotation process, and improving the safety performance of the aircraft.

At a location about 42.1% from the center of the propeller disk, i.e., at the A-A cross section that has a distance H1from the center of the propeller disk as shown inFIG. 7, the chord length L1of the blade, as shown inFIG. 8, is about 23.98 mm±5 mm, the angle of attack α1is about 20.96°±2.5°.

At a location about 60.7% from the center of the propeller disk, i.e., at the B-B cross section that has a distance H2from the center of the propeller disk as shown inFIG. 7, the chord length L2of the blade, as shown inFIG. 9, is about 20.03 mm±5 mm, the angle of attack α2is about 16.61°±2.5°.

At a location about 93.5% from the center of the propeller disk, i.e., at the F-F cross section that has a distance H6from the center of the propeller disk as shown inFIG. 7, the chord length L6of the blade, as shown inFIG. 13, is about 8.29 mm±5 mm, the angle of attack α6is about 10.04°±2.5°.

At a location about 98.1% from the center of the propeller disk, i.e., at the G-G cross section that has a distance H7from the center of the propeller disk as shown inFIG. 7, the chord length L7of the blade, as shown inFIG. 14, is about 6.18 mm±5 mm, the angle of attack α7is about 9.35°±2.5°.

A person having ordinary skills in the art can appreciate that the locations of the above cross sections A-A, B-B, F-F, and G-G are not limited to the above embodiments, which may be changed slightly.

For the above embodiments, the present disclosure provides a specific propeller. The diameter of the propeller is 107 mm, the length of the blade is 95 mm. At a location about 85 mm from the center of the propeller disk, the chord length of the blade is 16.39 mm, the angle of attack is 12.94°. At a location about 90 mm from the center of the propeller disk, the chord length of the blade is 15.05 mm, the angle of attack is 11.55°. At a location about 95 mm from the center of the propeller disk, the chord length of the blade is 11.42 mm, and the angle of attack is 10.69°.

Further, at a location about 45 mm from the center of the propeller disk, the chord length of the blade is 23.98 mm, the angle of attack is 20.96°. At a location about 65 mm from the center of the propeller disk, the chord length of the blade is 20.03 mm, the angle of attack is 16.61°. At a location about 100 mm from the center of the propeller disk, the chord length of the blade is 8.29 mm, the angle of attack is 10.04°. At a location about 105 mm from the center of the propeller disk, the chord length of the blade is 6.18 mm, the angle of attack is 9.35°. It can be understood that because the locations of the cross sections A-A, B-B, F-F, and G-G may be slightly changed, correspondingly, the angles of attack and the chord lengths at the cross sections A-A, B-B, F-F, and G-G may be correspondingly changed.

In some embodiments, the pitch of the propeller may be 31 mm, i.e., the distance of rise is 31 mm when the propeller rotates one circle.

For the above propeller of the present embodiment, when compared with a propeller of a conventional technology, the overall noise may be reduced from 72 dB to 69 dB, and the hovering power consumption of the propeller may only reduce by 4-5%. That is, the above propeller can have an excellent aerodynamic efficiency while having a reduced noise.

Further, the propeller of the present embodiment can be suitable for dual-axis aircraft, quad-axis aircraft, or octa-axis aircraft.FIG. 15is a schematic illustration of a structure of the propeller according to an embodiment. As shown inFIG. 15, the propeller may include a blade hub200. The blade hub200may be connected with two, three, or more than three blades. The blade hub200may cause the blades to rotate to form the propeller disk. The blade hub200and the blades may be an integrally structure. Alternatively, the propeller may be a separate-body propeller, in which the blades may be individually and separately mounted onto the blade hub200. For example, a mounting hole170may be formed at the blade root110of the blade. The blade may be mounted to the blade hub200through the mounting hole170.

Specifically, the propeller may be a self-tightening blade as shown inFIG. 15. The blade hub200of the self-tightening blade may include a connection hole210configured for connecting with an output shaft of the electric motor. In some embodiments, the self-tightening blade means that the blade hub200of the propeller is provided with a self-locking mechanism coupled with the aircraft body. When the connection hole210of the blade hub200is sleeve-fit onto the output shaft of the electric motor and when the aircraft is started up, the self-locking mechanism provided on the aircraft body and the blade hub200may tightly lock the propeller on the aircraft body, thereby avoiding ejecting of the blade or crash. For example, a groove may be provided on the blade hub200, and a pawl controlled by a cam mechanism may be provided on the aircraft body. When the aircraft is started up, the cam mechanism may rotate to cause the pawl to move in an axial direction of the blade hub200to tightly lock the blade hub200. Alternatively, a disk-shaped structure may be controlled by an electromagnet to move along an axial direction of the blade hub200, thereby tightly pressing the wheel hub between the disk-shaped structure and the aircraft body to realize the tight locking of the blade hub200having multiple blades.

The propeller may be a foldable propeller. The multiple blades and arms may be folded to be parallel with the aircraft body or close to the aircraft body to reduce the volume of the aircraft for the convenience of transportation and storage.FIG. 16is a schematic illustration of a structure of a wheel hub of a foldable propeller. As shown inFIG. 16, the blade hub200of the foldable propeller may include a first connection member220, a second connection member230, and a third connection member240. The first connection member220may be connected with the blades. For example, a fastener may penetrate through the mounting hole170provided on the blade root110of the blade to fix the blade on the first connection member220. The second connection member230may be connected with a driving member. For example, the second connection member230may be sleeve-fit onto the output shaft of the electric motor or the engine, such that the electric motor or the engine drive the wheel hub to cause the blades to rotate, to form the propeller disk, thereby generating a lifting force or a propulsion force to drive the manned or unmanned aircraft to move. The third connection member240may be disposed between the first connection member220and the second connection member230to connect the first connection member220and the second connection member230.

In some embodiments, the aircraft may include two, three, or more than three third connection members240, separately disposed between the first connection member220and the second connection member230. The multiple third connection members240may be uniformly disposed between the first connection member220and the second connection member230. For example, three third connection members240may be uniformly disposed between the first connection member220and the second connection member230.

In the foldable propeller of the present disclosure, by connecting the first connection member220and the second connection member230through the third connection member240, the weight of the propeller can be reduced, and the flight performance of the propeller can be enhanced. In particular, when the blade hub200and the blades of the propeller are an integral structure, the flight performance can be significantly improved. The third connection member240separately disposed between the first connection member220and the second connection member230can not only improve the structural strength of the propeller, but also improve the stability of the propeller during a flight, thereby improving the flight performance of the propeller. When manufacturing the blade hub200, the connection portions between the third connection member240and the first connection member220and the second connection member230may have a smooth transition, thereby reducing the stress at the connection portions, and improving the reliability of the blade hub200.

A person having ordinary skills in the art can appreciate that the propeller can be a normal rotation propeller or a reverse rotation propeller. The normal rotation propeller means from a top view perspective of the aircraft, the propeller generates a lifting fore in a clockwise rotation; the reverse rotation propeller means from a top view perspective of the aircraft, the propeller generates the lifting force in a counter-clockwise rotation. The structure of the normal rotation propeller and the structure of the reverse rotation propeller are mirror symmetric.

The present disclosure also provides a propulsion assembly, including a driving member and a propeller described above. The propeller may be connected with an output shaft of the driving member through the wheel hub. The driving member may be an electric motor. The KV value of the electric motor may be 1300 rounds/(minute·volt), 1500 rounds/(minute·volt), or any value between the two values, such as 1400 rounds/(minute·volt).

In the propulsion assembly, by forming the first suppression member180through bending a portion of the front edge150of the blade adjacent to the blade tip120toward the rear edge160, the spanwise air flow on the blade may be cut, thereby reducing the formation of the blade tip turbulence or reducing the intensity of the blade tip turbulence. As a result, the rotation noise of the propeller generated in the rotation process may be reduced, thereby improving the safety of the manned or unmanned aircraft (e.g., UAV or airship).

FIG. 17is a schematic illustration of a structure of the aircraft. As shown inFIG. 17, the present disclosure also provides an aircraft, including an aircraft frame10, an aircraft arm20, and at least one propulsion assembly30. An end of the aircraft arm20is connected with the aircraft frame10. The other end of the aircraft arm20is configured for mounting the propulsion assembly30. The above described aircraft may be a manned aircraft, such as an airship, or may be a rotor-based unmanned aircraft, such as a quad-rotor UAV. The aircraft may include the above described propulsion assembly30. By forming the first suppression member180through bending a portion of the front edge150of the blade toward the rear edge160, the spanwise air flow on the blade may be cut, thereby reducing the formation of the blade tip turbulence or reducing the intensity of the blade tip turbulence. As a result, the rotation noise generated by the propeller during the rotation process can be reduced, and the safety of the manned or unmanned aircraft (e.g., UAV or airship) can be improved.

In some embodiments, the aircraft arm20may be fixed to the aircraft frame10or may be rotatably connected with the aircraft frame10. When the aircraft arm20is rotatably connected to the aircraft frame10, the volume of the aircraft may be reduced, which makes it convenient for transportation and storage.

Finally, although the advantages related to some embodiments have been described in the context of the above embodiments, other embodiments may also have such advantages. Not all embodiments have explicitly described all advantages of the present disclosure. The advantages brought by the technical features of the embodiments should all be regarded as advantages that distinguish the present disclosure from the conventional technologies, which should belong to the scope of protection of the present disclosure.