Duct opening and closing structure of fixed-wing large-duct aircraft

Abstract

The invention discloses a duct opening and closing structure of a fixed-wing large-duct aircraft. The duct opening and closing structure comprises a plurality of turnover grating blades distributed on the upper surface and the lower surface of a duct and a driving mechanism used for synchronously driving all the grating blades to be switched between the opening position and the closing position. At the opening position, the grating blades on the upper surface of the duct are overturned upwards, and the grating blades on the lower surface of the duct are overturned downwards; and at the closing position, all the grating blades are overturned towards the interior of the duct to be in a horizontal state, and the front edges and the rear edges of the adjacent grating blades are in lap joint to form a continuous closed surface. According to the design of the turnover grating blades, in the level flight stage of the aircraft, all the grating blades turn over towards the interior of the duct to be in the horizontal state, a continuous closed face is formed through lap joint of the front edge and the rear edge, a duct cavity is thoroughly eliminated, turbulent flow generated when airflow penetrates through the cavity is avoided, interference to the airflow on the surfaces of wings is greatly reduced, and the flying speed of the aircraft is increased. And the aerodynamic resistance is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of electric vertical takeoff and landing (eVTOL) aircraft structural design, and in particular to a duct opening and closing structure for a fixed-wing high-ducted aircraft. Background Technology

[0002] The Evtol industry is currently booming, with various configurations of aircraft emerging one after another. High-ducted fan drones, due to their special structure where the propeller is enclosed by a duct, can prevent secondary damage to personnel and the fuselage when the propeller blades splash. The duct can also be fitted with sound-absorbing materials, further absorbing the aerodynamic noise generated by the propeller rotation, typically reducing the sound pressure level by about 10-20 dB, thus better meeting the stringent noise reduction requirements for low-altitude urban flight. During vertical takeoff and landing, lift is provided by the ducted fan. During level flight, the aircraft's lift is mainly provided by the fixed wings. At this time, the duct, in its non-operating state, forms an open cavity. Airflow passing through this cavity generates turbulence, disrupting the smoothness of airflow over the wing surface and significantly increasing aerodynamic drag. Therefore, during level flight, it is necessary to find ways to seal the upper and lower surfaces of the duct.

[0003] Some low-duct aircraft can close the duct by sliding the leading and trailing edges, while others use a large, flip-up cover to close the duct. However, neither of these methods is suitable for high-duct aircraft. The former requires increasing the wing size and changing the aerodynamic layout, while the latter introduces additional drag and makes it difficult to close the duct on the lower wing surface.

[0004] Therefore, it is necessary to design a duct opening and closing structure for fixed-wing high-ducted aircraft to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a duct opening and closing structure that has low aerodynamic drag, stable structure, and is suitable for large ducted aircraft.

[0006] The technical solution of the present invention is: a duct opening and closing structure for a fixed-wing large ducted aircraft, comprising multiple rotatable grid blades distributed on the upper and lower surfaces of the duct and a drive mechanism for synchronously driving all grid blades to switch between an open position and a closed position; in the open position, the grid blades on the upper surface of the duct flip upwards and the grid blades on the lower surface of the duct flip downwards; in the closed position, all grid blades flip inwards to a horizontal state, and the leading and trailing edges of adjacent grid blades overlap to form a continuous closed surface.

[0007] The grille blades are streamlined wing-shaped structures with internal I-beams, and the upper and lower flanges of the I-beams are connected to the upper skin and the lower skin, respectively. The leading edge is connected by a butt plate, and the end is filled with foam ribs to support the skin.

[0008] The drive mechanism includes two sets of servos symmetrically arranged on both sides of the duct via servo brackets, a turntable connected to the servo output shaft, a steel cable wound on the turntable, a slide plate connected to the end of the steel cable, a rack fixed on the slide plate, and a gear meshing with the rack and connected to the grid blade shaft; when one servo tightens the steel cable, the other servo releases the steel cable, driving the slide plate to move and drive the rack and gear transmission.

[0009] The steel cable path is equipped with pulleys and guide frames to prevent the steel cable from slipping out, via pulley brackets.

[0010] The bottom of the slide is equipped with rollers, and the slide slides on the track of the slide bracket via the rollers.

[0011] The gear is mounted on the duct rib via a bearing; the axial displacement of the bearing is limited by the bearing groove on the pulley bracket.

[0012] The pulley bracket is installed on the duct rib, and corner pieces are provided between adjacent pulley brackets; the corner pieces connect the duct skin and the duct rib.

[0013] The present invention has the following beneficial effects by adopting the above technical solution: (1) The design of the flip-out grid blades of the present invention enables all grid blades to flip into the duct to a horizontal state during the level flight phase of the aircraft, and form a continuous closed surface by overlapping the front and rear edges, completely eliminating the duct cavity, avoiding the turbulence generated when the airflow passes through the cavity, greatly reducing the interference to the airflow on the wing surface, and effectively reducing aerodynamic drag. (2) The present invention adopts mechanical transmission, which has high maturity and stability. Moreover, the driving force comes from the servo motor, which can reduce the types of aircraft equipment and has a certain degree of versatility. In addition, the turntable is designed and can be adjusted according to the wiring requirements. (3) The individual grid blades of the present invention are made into small airfoils to reduce aerodynamic drag, and beams can be arranged inside to improve the bending resistance of the grid. (4) The rotation direction of the grille of the present invention has little impact on the space inside the duct, which can reduce the height of the duct wing and reduce the drag during flight; (5) The present invention has rollers installed on the bracket to reduce the resistance between the bracket and the slide plate, thereby reducing the power of the servo motor; (6) The present invention restricts the axial movement of the bearing by means of the bearing groove and the pulley bracket, and the pulley bracket can be made of profile material, which can be cut as needed to reduce manufacturing costs; (7) The present invention uses individual servo motors to pull the slide plate in cooperation, and the steel cable on one side is always taut, which can maintain the direction of the grille and reduce the influence of airflow on the direction of the grille. Attached Figure Description

[0014] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0015] Figure 1 This is a schematic diagram of the structure of the present invention.

[0016] Figure 2 This is a diagram showing the state of the grille blades of the present invention when they are in the closed position.

[0017] Figure 3 This is a schematic diagram of the servo motor of the present invention.

[0018] Figure 4 This is a schematic diagram of the installation structure of the pulley and guide frame of the present invention.

[0019] Figure 5 This is a schematic diagram of the transmission of the gear and rack of the present invention.

[0020] Figure 6 This is a schematic diagram of the gear and rack transmission of the present invention from the rear.

[0021] Figure 7 This is a schematic diagram of the corner piece of the present invention.

[0022] Figure 8 This is a schematic diagram of the structure of the grid blade of the present invention.

[0023] The labels in the attached diagram are: 1. Grille blade, 2. Drive mechanism, 2-1. Servo bracket, 2-2. Servo, 2-3. Turntable, 2-4. Steel cable, 2-5. Slide plate, 2-6. Rack, 2-7. Gear, 2-8. Pulley bracket, 2-9. Pulley, 2-10. Guide frame, 2-11. Roller, 2-12. Bearing groove, 2-13. Corner piece, 2-14. Support plate bracket. Detailed Implementation

[0024] Example

[0025] See Figures 1 to 8 This embodiment discloses a duct opening and closing structure for a fixed-wing high-ductivity aircraft, comprising multiple rotatable grid blades 1 distributed on the upper and lower surfaces of the duct, and a drive mechanism 2 for synchronously driving all grid blades 1 to switch between an open and closed position. In the open position, the grid blades 1 on the upper surface of the duct flip upwards, and the grid blades 1 on the lower surface of the duct flip downwards. In the closed position, all grid blades 1 flip inwards to a horizontal state, and the leading and trailing edges of adjacent grid blades 1 overlap to form a continuous closed surface. This embodiment, through the design of the rotatable grid blades 1, achieves rapid switching between the open and closed states of the duct, ensuring smooth airflow in the open position and forming a continuous closed surface in the closed position, effectively reducing flight drag and improving aerodynamic efficiency, while also enhancing the overall structural integrity.

[0026] Furthermore, the grille blade 1 is a streamlined airfoil structure with an internal I-beam, and the upper and lower flanges of the I-beam are connected to the upper and lower skins respectively. The leading edge is connected by a butt-joint plate, and the end is filled with foam ribs to support the skin. The I-beam structure provides high-strength and lightweight support, the streamlined airfoil optimizes aerodynamic performance, and the closed leading edge and foam rib filling enhance the blade's stiffness and resistance to deformation while reducing weight.

[0027] Furthermore, the drive mechanism 2 includes two sets of servo motors 2-2 symmetrically arranged on both sides of the duct via servo motor brackets 2-1, a turntable 2-3 connected to the output shaft of the servo motors 2-2, a steel cable 2-4 wound on the turntable 2-3, a slide plate 2-5 connected to the end of the steel cable 2-4, a rack 2-6 fixed to the slide plate 2-5, and a gear 2-7 meshing with the rack 2-6 and connected to the rotating shaft of the grille blade 1. When one servo motor 2-2 tightens the steel cable 2-4, the other servo motor 2-2 releases the steel cable 2-4, driving the slide plate 2-5 to translate and drive the rack 2-6 and gear 2-7 to transmit power. The symmetrical drive design of the dual servo motors 2-2 ensures synchronization and reliability, the transmission of the steel cable 2-4 realizes long-distance power transmission, and the rack 2-6 and gear 2-7 structure converts linear motion into rotational motion, efficiently and accurately controlling the blade rotation.

[0028] Furthermore, the path of the steel cable 2-4 is provided with pulleys 2-9 and guide frames 2-10 to prevent the steel cable 2-4 from slipping off, via pulley brackets 2-8. The pulleys 2-9 reduce friction and wear on the steel cable 2-4, and the guide frames 2-10 prevent the steel cable 2-4 from slipping off, thereby improving the stability and lifespan of the transmission system.

[0029] Furthermore, the bottom of the slide plate 2-5 is provided with rollers 2-11, and the slide plate 2-5 slides on the track of the pallet bracket 2-14 via the rollers 2-11. The sliding design of the rollers 2-11 reduces the frictional resistance of the slide plate 2-5 movement, ensures the smooth movement of the slide plate 2-5, and improves the response speed and accuracy of the drive mechanism 2.

[0030] Furthermore, the gear 2-7 is mounted on the duct rib via a bearing; the axial displacement of the bearing is limited by the bearing groove 2-12 on the pulley bracket 2-8. The bearing support reduces the friction of the gear 2-7 rotation, and the bearing groove 2-12 limits the axial displacement, ensuring stable meshing between the gear 2-7 and the rack 2-6 and preventing transmission failure.

[0031] Furthermore, the pulley brackets 2-8 are mounted on the duct ribs, and corner pieces 2-13 are provided between adjacent pulley brackets 2-8; the corner pieces 2-13 connect both the duct skin and the duct ribs. The combined design of the pulley brackets 2-8 and the corner pieces 2-13 enhances the overall rigidity and strength of the duct structure, while providing a stable mounting foundation for the drive mechanism 2, ensuring long-term reliable operation of the system.

[0032] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A duct opening and closing structure for a fixed-wing high-ducted aircraft, characterized in that: It includes multiple flip-out grid blades (1) distributed on the upper and lower surfaces of the duct and a drive mechanism (2) for synchronously driving all grid blades (1) to switch between open and closed positions; in the open position, the grid blades (1) on the upper surface of the duct flip upward and the grid blades (1) on the lower surface of the duct flip downward; in the closed position, all grid blades (1) flip into the duct to a horizontal state, and the leading and trailing edges of adjacent grid blades (1) overlap to form a continuous closed surface.

2. The duct opening and closing structure for a fixed-wing high-ducted ducted aircraft according to claim 1, characterized in that: The grille blade (1) is a streamlined wing structure with an internal I-beam, and the upper and lower flanges of the I-beam are connected to the upper skin and the lower skin respectively. The leading edge is connected by a butt plate, and the end is filled with foam ribs to support the skin.

3. The duct opening and closing structure for a fixed-wing high-ducted aircraft according to claim 1 or 2, characterized in that: The drive mechanism (2) includes two sets of servo motors (2-2) symmetrically arranged on both sides of the duct via servo motor brackets (2-1), a turntable (2-3) connected to the output shaft of the servo motor (2-2), a steel cable (2-4) wound on the turntable (2-3), a slide plate (2-5) connected to the end of the steel cable (2-4), a rack (2-6) fixed on the slide plate (2-5), and a gear (2-7) meshing with the rack (2-6) and connected to the rotating shaft of the grid blade (1); when one side servo motor (2-2) tightens the steel cable (2-4), the other side servo motor (2-2) releases the steel cable (2-4), driving the slide plate (2-5) to translate and drive the rack (2-6) and gear (2-7) to transmit power.

4. The duct opening and closing structure for a fixed-wing high-ducted aircraft according to claim 3, characterized in that: The steel cable (2-4) path is provided with pulleys (2-9) and guide frames (2-10) to prevent the steel cable (2-4) from falling off, via pulley brackets (2-8).

5. The duct opening and closing structure for a fixed-wing high-ducted aircraft according to claim 3, characterized in that: The bottom of the slide plate (2-5) is provided with rollers (2-11), and the slide plate (2-5) slides on the track of the slide plate bracket (2-14) via the rollers (2-11).

6. The duct opening and closing structure for a fixed-wing high-ducted aircraft according to claim 3, characterized in that: The gear (2-7) is mounted on the duct rib by a bearing; the axial displacement of the bearing is limited by the bearing groove (2-12) on the pulley bracket (2-8).

7. The duct opening and closing structure for a fixed-wing high-ducted ducted aircraft according to claim 6, characterized in that: The pulley bracket (2-8) is installed on the duct rib, and a corner piece (2-13) is provided between adjacent pulley brackets (2-8); the corner piece (2-13) connects the duct skin and the duct rib.

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