Low-resistance multi-rotor unmanned aerial vehicle arm

Abstract

The application provides a low-resistance multi-rotor unmanned aerial vehicle arm, which comprises an arm body, the arm body is a prism with an unchanged cross section along the length direction, and the cross section along the length direction of the arm body comprises: an upper edge line and a lower edge line, the upper edge line and the lower edge line are horizontal line segments arranged in parallel and with equal length; a left side edge line and a right side edge line, the left side edge line and the right side edge line are circular arc lines arranged in parallel to each other and perpendicular to the upper edge line; the outward convex circular arc directions of the left side edge line and the right side edge line are the same as the rotating directions of the propellers of the unmanned aerial vehicle, the maximum aerodynamic lift is improved by utilizing the extrusion effect of the upper edge line of the cross section of the arm body and the propeller blades, the inclination angles are formed by arranging two circular arc lines arranged in parallel to each other and perpendicular to the upper edge line, the air flow is guided to smoothly flow through the arm surface, the resistance caused by the vortex of the air flow is reduced, the total aerodynamic resistance is reduced, the lift power ratio is improved, and the flight performance of the unmanned aerial vehicle is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of multi-rotor unmanned aerial vehicle, in particular to a low-resistance multi-rotor unmanned aerial vehicle arm. BACKGROUND

[0002] Multi-rotor unmanned aerial vehicle is an important carrier for realizing low-altitude logistics, low-altitude transportation, agricultural plant protection and environmental monitoring in low-altitude economy of China, and also serves the general consumers in aerial photography, competitive entertainment, security and other social life, and even plays an important role in war.

[0003] How to improve the endurance time, flight speed, maximum load and other performance parameters of multi-rotor unmanned aerial vehicle is one of the core problems of multi-rotor unmanned aerial vehicle design, and the lift power ratio and aerodynamic resistance of unmanned aerial vehicle are the key factors affecting its flight efficiency, endurance capacity and aerodynamic performance, the greater the aerodynamic resistance, the smaller the lift power ratio, and the poorer the flight performance of the unmanned aerial vehicle, the existing unmanned aerial vehicle arm section is mostly circular or square, which generates about 5% to 12% of the total aerodynamic resistance in the flight state, and the total aerodynamic resistance is too large, resulting in poor flight performance of the unmanned aerial vehicle.

[0004] Therefore, the present application person specially designs a low-resistance multi-rotor unmanned aerial vehicle arm, and the present application is generated. SUMMARY

[0005] In order to solve the above problems, the technical scheme of the present application is as follows:

[0006] A low-resistance multi-rotor unmanned aerial vehicle arm, comprising:

[0007] The arm body is a prism with a constant cross-sectional profile along the length direction, the cross section of the arm body along the length direction is an irregular quadrilateral, and the cross section of the arm body along the length direction comprises:

[0008] The upper edge line and the lower edge line are horizontal line segments arranged in parallel and equal length;

[0009] The left side edge line and the right side edge line are circular arc lines parallel to each other and perpendicular to the upper edge line; the convex circular arc direction of the left side edge line and the right side edge line is the same as the rotation direction of the propeller of the unmanned aerial vehicle.

[0010] Preferably, the angle of the central angle corresponding to the left side edge line and the right side edge line is 25° to 35°.

[0011] Preferably, the angle of the central angle corresponding to the left side edge line and the right side edge line is 30°.

[0012] Preferably, the upper edge line, the lower edge line, the left side edge line and the right side edge line are 5mm-15mm in length, and the arm body is 45mm-55mm in length.

[0013] Preferably, the arm body is internally provided with a hollow cavity extending along the length direction.

[0014] Preferably, the cross-sectional profile of the hollow cavity is coaxially arranged with the cross-sectional outer profile of the arm body.

[0015] Preferably, the surface roughness of the arm body is ≤3.2μm.

[0016] Preferably, one end of the arm body is provided with a quick-release structure connected with the fuselage, and the other end is provided with a damping structure connected with the motor, and the motor is connected with the propeller.

[0017] The technical scheme provided by the present application has the following beneficial effects:

[0018] 1. The present application utilizes the extrusion effect of the upper edge line of the cross section of the arm body and the propeller blade to improve the maximum aerodynamic lift, forms an inclination angle by arranging two mutually parallel and vertical circular arcs with the upper edge line, and the circular arcs are convex in the same direction as the rotation direction of the propeller, thereby reducing the windward area of the arm and the aerodynamic drag, and guiding the airflow to smoothly flow over the surface of the arm through the smooth transition of the circular arc, thereby reducing the resistance caused by vortex of the airflow, achieving the purpose of reducing the total aerodynamic drag, improving the lift power ratio, and further improving the flight performance of the unmanned aerial vehicle.

[0019] 2. The present application internally provides a hollow cavity in the arm body, which can greatly reduce the weight of the arm body, reduce the overall mass of the unmanned aerial vehicle, thereby reducing the power consumption during hovering and flight, improving the lift power ratio, and prolonging the endurance time. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application.

[0021] Wherein:

[0022] Figure 1 is a schematic diagram of the overall structure of the present application.

[0023] Figure 2 is a schematic diagram of the assembly structure of the present application and the fuselage.

[0024] Figure 3 is a schematic diagram of the cross-sectional structure of the arm body of the present application.

[0025] Figure 4 is a schematic diagram of the airflow movement direction in the present application.

[0026] Reference Signs List:

[0027] 1, arm body; S1, upper edge line; S2, lower edge line; S3, right side edge line; S4, left side edge line; 2, hollow cavity; 3, quick release structure; 4, damping structure; 5, fuselage; 6, motor; 7, propeller. DETAILED DESCRIPTION

[0028] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clear and explicit, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0029] Please refer to Figures 1-4 , as a low-resistance multi-rotor unmanned aerial vehicle arm of the best embodiment of the present application, including arm body 1, arm body 1 is a prism with unchanged cross-sectional profile along the length direction, the cross section of arm body 1 along the length direction is an irregular quadrilateral, compared with a simple rectangular or circular cross section, it can provide higher bending stiffness and torsional strength under the same weight, reduce the power consumption of the unmanned aerial vehicle in the flight process, improve the flight performance of the unmanned aerial vehicle, the cross section of arm body 1 along the length direction includes: upper edge line S1 and lower edge line S2, upper edge line S1 and lower edge line S2 are parallel and equally long horizontal line segments; the upper edge line S1 of the cross section of the arm body 1 is a horizontal line segment, when the propeller 7 of the unmanned aerial vehicle rotates above the arm body 1, the air volume between the propeller 7 and the upper edge line S1 of the cross section of the arm body 1 is reduced, the gas is compressed, the compressed gas is increased and flows downward quickly, increasing the kinetic energy of the airflow, the upper edge line S1 and the lower edge line S2 are parallel and equally long, providing structural symmetry, ensuring that the arm body 1 is uniformly stressed, avoiding the vibration caused by aerodynamic asymmetry; left side edge line S4 and right side edge line S3, left side edge line S4 and right side edge line S3 are mutually parallel and perpendicular to upper edge line S1 circular arc; the convex circular arc direction of left side edge line S4 and right side edge line S3 is the same as the rotation direction of the propeller 7 of the unmanned aerial vehicle, Figure 4The middle arrow direction represents the direction of the airflow, the outer convex direction is consistent with the rotation direction of the propeller 7, and under the action of the torque of the propeller 7, an opposite aerodynamic moment and a rolling moment are generated to maintain the stability of the unmanned aerial vehicle flight. The left side line S4 and the right side line S3 are circular arcs, which can make the stress distribution of the arm body 1 more uniform, reduce local stress concentration, prolong the fatigue life, effectively reduce the windward area of the arm body 1, that is, the projection area of the arm body 1 in the vertical airflow direction, thereby reducing the aerodynamic resistance, and making the airflow flowing through the outer surface of the arm body 1 smoothly transition, improving the flight performance of the unmanned aerial vehicle, and under crosswind conditions, the circular arc side line can reduce the lateral wind resistance and enhance the stability of the unmanned aerial vehicle flight.

[0030] Specifically, please refer to Figure 1 and Figure 3 The angle of the central angle α corresponding to the left side line S4 and the right side line S3 is 25°-35°.

[0031] Specifically, the angle of the central angle α corresponding to the left side line S4 and the right side line S3 in the embodiment is 30°, which can better reduce the windward area of the arm body 1 and guide the smooth transition of the airflow, while avoiding sharp edge cutting of the airflow, reducing the rotor-induced resistance, reducing the power consumption of the unmanned aerial vehicle during hovering and flight, and improving the flight performance and endurance of the unmanned aerial vehicle. The angle of the central angle α of 30° provides a smoother airflow transition than a smaller angle (such as 15°), significantly reduces airflow separation, and better maintains structural rigidity than a larger angle (such as 45°), avoiding weakening of the side wall strength.

[0032] Specifically, please refer to Figure 1 and Figure 3 The upper edge line S1, the lower edge line S2, the left side line S4 and the right side line S3 are the same length, and the lengths of the four edges are the same, which can improve the strength of the unmanned aerial vehicle arm body 1, improve the deformation resistance, make the unmanned aerial vehicle more stable during flight, and the equal length design of the upper edge line S1 and the lower edge line S2 can form a stable air cushion between the arm body 1 and the downwash airflow of the propeller 7, improve the hovering efficiency of the unmanned aerial vehicle, reduce the energy consumption of the unmanned aerial vehicle during hovering, and improve the flight performance of the unmanned aerial vehicle.

[0033] Specifically, please refer to Figure 1 and Figure 3The upper edge line S1, the lower edge line S2, the left side edge line S4 and the right side edge line S3 have a length of 5mm-15mm, and the arm body 1 has a length of 45mm-55mm. In the embodiment, the upper edge line S1, the lower edge line S2 and the side edge line in the cross section of the arm body 1 have a length of 10mm, and the arm body 1 has a length of 50mm. Most of the existing civilian unmanned aerial vehicles are small unmanned aerial vehicles. The shorter longitudinal length and the arc-shaped side edge line can improve the anti-falling performance of the arm body 1, make the airflow smoothly transition, improve the wind resistance, enhance the stability of the unmanned aerial vehicle in flight, improve the lift power ratio, and prolong the endurance time.

[0034] Specifically, please refer to Figures 1-3 The arm body 1 is internally provided with a hollow cavity 2 penetrating along the length direction. In the embodiment, the hollow cavity 2 has the same cross-sectional shape as the outer contour shape of the arm body 1. In the case of maintaining the outer wall thickness, the hollow design can greatly reduce the weight of the arm body 1, reduce the overall mass of the unmanned aerial vehicle, thereby reducing the power consumption during hovering and flight, improving the lift power ratio, prolonging the endurance time, and at the same time, the hollow cavity 2 can exist as a flow guide channel, play a flow guiding role on the flight airflow, reduce the aerodynamic drag, reduce the resistance caused by the vortex of the airflow, achieve the purpose of reducing the total aerodynamic drag, improving the lift power ratio, and further improving the flight performance of the unmanned aerial vehicle.

[0035] Specifically, please refer to Figures 1-3 The cross-sectional contour of the hollow cavity 2 is coaxially arranged with the cross-sectional outer contour of the arm body 1, and the stress distribution is optimized. The coaxial design of the hollow cavity 2 makes the load uniformly transmitted along the wall thickness. When the airflow enters, it can avoid the unstable vibration of the airflow on the arm body 1, can make the airflow entering the hollow cavity 2 form a stable airflow, improve the stability of the unmanned aerial vehicle in flight, improve the lift power ratio, and achieve the purpose of improving the flight performance of the unmanned aerial vehicle. At the same time, compared with the eccentric structure, the design improves the bending stiffness and the ultimate load capacity, prolongs the service life of the arm body 1, reduces the interference of the downwash airflow when the propeller 7 blade rotates, avoids airflow resonance, and affects the flight performance of the unmanned aerial vehicle.

[0036] Specifically, please refer to Figure 1 and Figure 2The surface roughness of the arm body 1 is less than or equal to 3.2 microns, in the embodiment, the surface roughness of the arm body 1 is 3.2 microns, the lower the surface roughness of the arm body 1, the lower the aerodynamic resistance and friction resistance caused by the vortex of the airflow, and the circular arc line of the side line cooperates with each other to reduce the windward area of the arm body 1, and make the airflow smooth transition, improve the laminar flow area of the airflow, reduce the resistance and power consumption of the unmanned aerial vehicle in flight, improve the flight performance of the unmanned aerial vehicle, and at the same time, the surface roughness of the arm body 1 is reduced, the surface hardness is improved, and the possibility of crack of the arm body 1 is reduced, and the service life of the arm body 1 is improved.

[0037] Specifically, refer to Figures 1-4 One end of the arm body 1 is provided with a quick release structure 3 connected with the fuselage 5, and the other end is provided with a damping structure 4 connected with the motor 6, and the motor 6 is connected with the propeller 7, in the embodiment, the arm body 1 is fixedly connected with the fuselage through the quick release structure 3, and is fixedly connected with the motor through the damping structure 4, and the motor is fixedly connected with the propeller 7 through the shaft, when the unmanned aerial vehicle flies, the damping mechanism can reduce the vibration caused by the rotation of the propeller 7, improve the stability of the unmanned aerial vehicle flight, reduce the additional power consumed by the unmanned aerial vehicle due to vibration, and improve the flight performance of the unmanned aerial vehicle, wherein the input voltage of the motor is 3.5V to 3.8V, the maximum input current is 7.5A, and the maximum rotating speed of the motor is 18000rpm, in the embodiment, the cross-sectional shape of the provided arm body 1 has obvious low resistance effect on the existing arm body 1, compared with the circular cross-section and the square cross-section of the arm, in order to ensure the fairness of comparison, the perimeters of the three arm cross-sections are kept equal, and table 1 lists the lift power ratio values measured under three kinds of arm cross-section shapes, from the table, it can be seen that when the input voltage of the motor is 3.5V to 3.8V, the lift power ratio measured by the low resistance cross-section proposed in the application is the highest, the lift power ratio is 3.7% (average value) higher than that of the circular cross-section arm, and the lift power ratio is 2.1% (average value) higher than that of the square cross-section arm.

[0038] Table 1: Unmanned aerial vehicle lift power ratio list (unit: N / W)

[0039]

[0040] In summary, the present application improves the maximum aerodynamic lift by utilizing the extrusion effect of the upper edge line S1 of the cross section of the arm body 1 and the propeller, reduces the windward area of the arm by setting two circular arc lines which are parallel to each other and perpendicular to the upper edge line S1, reduces the aerodynamic resistance of the arm, and at the same time, the circular arc smooth transition guides the airflow to flow smoothly over the surface of the arm, reduces the resistance caused by the vortex of the airflow, reduces the total aerodynamic resistance, improves the lift power ratio, and improves the flight performance of the unmanned aerial vehicle.

[0041] The application has been described above with reference to the drawings, and it will be apparent that the specific implementation of the application is not limited to the above-described manner, and that various non-essential improvements or direct application of the inventive concept and technical solutions of the application to other occasions without modification are within the scope of protection of the application.

Claims

1. A low-drag multi-rotor unmanned aerial vehicle (UAV) arm, characterized in that, Includes a robotic arm body (1), wherein the robotic arm body (1) is a prism whose cross-sectional outer contour remains unchanged along the length direction, and the cross-section of the robotic arm body (1) along the length direction is an irregular quadrilateral, the cross-section of the robotic arm body (1) along the length direction includes: The upper edge (S1) and the lower edge (S2) are horizontal line segments that are parallel and of equal length. The left side line (S4) and the right side line (S3) are parallel arcs that are perpendicular to the upper side line (S1); the outward convex arcs of the left side line (S4) and the right side line (S3) are in the same direction as the rotation of the UAV's propeller (7). The central angles corresponding to the left side line (S4) and the right side line (S3) are 25° to 35°. The top edge (S1), bottom edge (S2), left edge (S4), and right edge (S3) are all the same length.

2. The low-drag multi-rotor UAV arm according to claim 1, characterized in that, The central angles corresponding to the left side line (S4) and the right side line (S3) are 30°.

3. The low-drag multi-rotor UAV arm according to claim 1, characterized in that, The lengths of the upper edge (S1), lower edge (S2), left edge (S4) and right edge (S3) are 5mm to 15mm, and the length of the arm body (1) is 45mm to 55mm.

4. The low-drag multi-rotor UAV arm according to claim 1, characterized in that, The arm body (1) has a hollow cavity (2) that runs through the length direction.

5. The low-drag multi-rotor UAV arm according to claim 4, characterized in that, The cross-sectional profile of the hollow cavity (2) is coaxially set with the outer cross-sectional profile of the arm body (1).

6. The low-drag multi-rotor UAV arm according to claim 1, characterized in that, The surface roughness of the arm body (1) is ≤3.2μm.

7. The low-drag multi-rotor UAV arm according to claim 1, characterized in that, One end of the arm body (1) is provided with a quick-release structure (3) connected to the body (5), and the other end is provided with a shock-absorbing structure (4) connected to the motor (6). The motor (6) is connected to the propeller (7).

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