Retractable flapping wing mechanism of micro flapping wing air vehicle

Abstract

The invention discloses a retractable flapping wing mechanism based on a miniature flapping wing air vehicle, which simulates the flapping wing folding and unfolding motion of ladybirds at wing roots, replaces a common rigid connection form with a compliant mechanism, and realizes the folding and unfolding motion of a flapping wing leading edge beam of the miniature air vehicle by utilizing the deformation of a strip-shaped spring. According to the mechanism, the flapping wings are folded to the two sides of the aircraft body through bending deformation of the strip-shaped springs, the spanwise size of the aircraft during storage can be effectively reduced, and the portability is improved; before the aircraft takes off, the flapping wings can be automatically unfolded by releasing the strain energy of the strip-shaped spring. According to the design, the occupied space of the aircraft is reduced, the launching distance of the unmanned aerial vehicle is increased, the task execution radius is increased, and the application scene is expanded.

Description

Technical Field

[0001] The invention relates to the field of micro flapping-wing aircraft, in particular to a retractable flapping-wing mechanism of a micro flapping-wing aircraft. Background Art

[0002] Bionic micro flapping-wing aircraft are characterized by their small size, light weight, high maneuverability, and good concealment, and have broad application prospects in both military and civilian scenarios. To increase the aircraft's range of motion, the actual execution of the mission often requires a specific launch method to achieve long-distance transport. Due to the aircraft's delicate structure and the thin, fragile material of its flapping wings, it needs to be stored in a sealed container and launched together with the container. Compared to simple hand-thrown launches, container-type launchers offer greater practical application value in terms of launch speed and aircraft protection. After launch, the flapping-wing aircraft can use inertia to move a certain distance through the air at a high initial velocity. When approaching its destination, it detaches from the container and continues to fly under its own power.

[0003] Limited by the rigid connection between the wings and the body, most currently known flapping-wing micro-aircraft (MAFs) can only maintain their wings in the extended state, preventing further reduction in spanwise dimensions. Due to the relatively small mass of a MAF, launching it directly with its wings extended would result in a larger launch container, leading to greater air resistance and a higher mass-to-weight ratio (resistance-to-mass ratio), making long-distance transport difficult. Therefore, reducing the launch size of the MAF is crucial for achieving long-distance transport.

[0004] In nature, insects like ladybugs can fold their wings to their sides and stow them beneath their elytra when resting, achieving both self-protection and significantly reducing their size. Research has discovered that insect wings contain a structure similar to a ribbon spring that allows them to bend and deform. Under external force, the ribbon spring structure bends and stores strain energy; when the external force is removed, the structure releases the strain energy and unfolds. Inspired by this, through the rational design of the flapping wing root connection, the flapping wings can be folded close to the side of the aircraft, reducing the spanwise size of the aircraft. The launch container can also be further optimized into a more compact cylindrical form, helping to reduce air resistance and increase the flight radius. Without the constraints of the container, the structure can drive the leading edge beam of the flapping wing to unfold, and the ribbon spring structure self-locks to maintain the flapping wings in the open configuration. Summary of the Invention

[0005] The present invention targets the field of retractable flapping wings for micro flapping-wing aircraft, and proposes to add a function to the existing micro flapping-wing aircraft to realize the folding and unfolding of the flapping wings at the root position, so as to better simulate the natural state of insects, that is, when resting, the wings are folded from the wing roots to the sides of the body to reduce the space occupied, and when about to take off, the folded wings are unfolded. The corresponding bionic design can effectively reduce the storage space of the aircraft, enrich the usage scenarios, and improve the concealment and portability of the aircraft.

[0006] The retractable and extending mechanism of the ladybug elytra imitating the micro flapping-wing aircraft is installed on the aircraft and comprises a strip spring, a flapping-wing leading edge beam, a fixing block, a stop block, and a flapping-wing root rotating member.

[0007] The strip spring is a three-dimensional structure with a certain thickness and an arc-shaped cross-section. The strip spring has a concave surface and a convex surface, both of which are arc surfaces, and the direction of the arc surface generatrix is ​​parallel to the axis direction of the strip spring. When no external force is applied, the strip spring maintains a straight and unfolded state. Under the action of a certain external force, the strip spring undergoes buckling instability, achieving bending deformation perpendicular to the axis and from the concave surface to the convex surface, and transforming into a folded state.

[0008] The leading edge beam of the flapping wing is a three-dimensional structure, which is a slender beam. The cross-section of the beam includes but is not limited to circular, rectangular, etc. This structure serves as the leading edge beam of the flapping wing, driving the flapping wing to perform reciprocating flapping motion.

[0009] The fixing block is a three-dimensional structure, and the main structure is a columnar structure. The main structure has four side surfaces, one of which is a cylindrical concave surface, and the other three side surfaces are flat surfaces. A through hole is punched at the bottom surface of the fixing block.

[0010] The stop block is a three-dimensional structure, and the main structure is a columnar structure. A through hole is punched at the side of the column, and the leading edge beam of the flapping wing passes through the through hole and is fixedly connected to the stop block; the bottom surface of the stop block on the side connected to the strip spring has an arc-shaped groove, which is consistent with the cross-sectional shape of the strip spring, so that the strip spring and the stop block are easily embedded; there are symmetrical bosses at the other pair of side positions of the column.

[0011] The flapping wing root rotating part is a three-dimensional structure, which is the output end component of the flapping wing aircraft transmission mechanism, and its rotational movement drives the flapping wing to flap back and forth; the lower side of the flapping wing root rotating part is an inverted groove structure, and the bottom surface of the groove structure is a cylindrical convex surface, which fits with the concave surface of the strip spring; there is a through hole on each side close to the rotating axis, which is coaxial with the through hole of the fixed block, so that the fixed block and the groove structure are matched; the position of the groove structure away from the rotating axis is a semi-open groove at the top, and the groove at this position cooperates with the stop block, and the outside of the groove has an end structure to limit the stop block from moving outward along the span direction of the flapping wing, and there is a groove structure at the end, and the groove width size matches the leading edge beam of the flapping wing, so that the leading edge beam of the flapping wing passes through the stop block and is embedded in the groove.

[0012] The retractable flapping-wing mechanism of a micro flapping-wing aircraft is characterized in that the concave surface on one side of the strip spring fits with the convex surface of the groove structure of the flapping-wing root rotating part, and the convex surface on the other side of the strip spring fits with the concave surface of the fixed block; the cooperation between the fixed block and the flapping-wing root rotating part limits the movement of the root of the strip spring in the downward direction.

[0013] The retractable flapping-wing mechanism of the micro flapping-wing aircraft is characterized in that the material and geometric dimensions (such as length, central angle of cross-sectional arc, etc.) of the strip spring should be matched through reasonable calculation and design to ensure that in the unfolded state, its bending stiffness can resist the torque generated by its own gravity, flapping wings and the weight of the stop block without buckling and instability; the material of the strip spring includes but is not limited to stainless steel, medium carbon steel, high carbon steel, copper alloy, carbon fiber composite material, etc.

[0014] The retractable flapping-wing mechanism of the micro flapping-wing aircraft is characterized in that the installation position of the flapping-wing leading edge beam should pass through the through hole of the stop block when the strip spring is in a straight state, and cooperate with the groove structure at the end of the flapping-wing root rotating part to maintain a horizontal state.

[0015] The method for implementing a retractable flapping-wing mechanism of a micro flapping-wing aircraft is characterized in that the strip spring becomes unstable and bends downward under a certain external force, driving the stop block and the flapping-wing leading edge beam to retract downward to the side of the aircraft body, and the maximum bending angle is close to 90 degrees; when the external force is removed, the strain energy of the strip spring is converted into mechanical energy, restored to a straight state, driving the stop block and the flapping-wing leading edge beam to unfold to a horizontal position, and the stop block is embedded in the semi-open groove of the flapping-wing root rotating part; under the action of lift, the stop block and the flapping-wing leading edge beam are subjected to an upward force without generating downward movement; the symmetrical boss of the stop block can play a limiting role, ensuring that the stop block and the flapping-wing leading edge beam will not move upward under the action of lift, thereby ensuring the subsequent flapping movement.

[0016] The installation method of the retractable flapping-wing mechanism of the micro flapping-wing aircraft is as follows:

[0017] (1) The strip spring and the stop block are fitted together and fixedly connected by bonding to prevent the stop block from separating from the strip spring; the adhesive used for bonding includes but is not limited to epoxy resin adhesive, acrylate adhesive, organic silicone adhesive, polyurethane adhesive, etc.;

[0018] (2) The stop block is installed in the semi-open groove at the top of the flapping wing root rotating member away from the rotation axis. At this time, the upper surface of the symmetrical boss of the stop block should be in contact with the lower surface of the corresponding side wall position of the flapping wing root rotating member to limit the upward movement of the stop block;

[0019] (3) One end of the strip spring close to the rotating shaft is fixedly connected to the fixed block and the flapping wing root rotating member by bonding, so as to limit the strip spring from moving outward along the flapping wing span direction in a bent state; the through hole of the fixed block is concentric with the side through hole of the flapping wing root rotating member close to the rotating shaft, and can be connected and fixed by a shaft pin;

[0020] (4) The stop block is matched with the flapping wing leading edge beam through a through hole and fixedly connected by bonding to limit the flapping wing leading edge beam from being separated from the stop block. After the connection, the flapping wing leading edge beam should be in a horizontal state; the bonding material is the same as that in step (1).

[0021] The advantages of the present invention are:

[0022] (1) The flapping wings can be folded close to the side of the aircraft body, reducing the span size of the aircraft;

[0023] (2) By reducing the size, the size of the launch container can be further optimized, which helps to reduce air resistance and increase the flight radius;

[0024] (3) Take insects in nature as inspiration to enhance the bionics of flapping-wing aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of a retractable flapping-wing mechanism of a flapping-wing micro aircraft according to the present invention in an expanded state;

[0026] Figure 2 Schematic diagram of a strip spring of a retractable flapping-wing mechanism of a micro flapping-wing aircraft according to the present invention in a straight state and a bent state;

[0027] Figure 3 It is a schematic diagram of a flapping wing leading edge beam of a retractable flapping wing mechanism of a flapping wing micro aircraft of the present invention;

[0028] Figure 4 It is a schematic diagram of a fixing block of a retractable flapping-wing mechanism of a micro flapping-wing aircraft of the present invention;

[0029] Figure 5 It is a schematic diagram of a stop block of a retractable flapping-wing mechanism of a flapping-wing micro aircraft of the present invention;

[0030] Figure 6 It is a schematic diagram of a flapping wing root rotating member of a retractable flapping wing mechanism of a flapping wing micro aircraft of the present invention;

[0031] Figure 7 1 is a schematic diagram of a retractable flapping-wing mechanism of a micro flapping-wing aircraft of the present invention in a retracted state;

[0032] In the picture:

[0033] 1-strip spring 2-flapping wing leading edge beam 3-fixed block 4-stop block

[0034]

[0035] 502-end structure DETAILED DESCRIPTION

[0036] The specific implementation method of the present invention is described in detail below with reference to the accompanying drawings.

[0037] The retractable and extending mechanism of the ladybug elytra based on the micro flapping-wing aircraft is as follows: Figure 1 As shown, it is installed on an aircraft and includes a strip spring 1, a flapping wing leading edge beam 2, a fixing block 3, a stop block 4, and a flapping wing root rotating part 5.

[0038] like Figure 2As shown, the strip spring 1 is a three-dimensional structure with a certain thickness and an arc-shaped cross-section. The strip spring 1 has a concave surface and a convex surface, both of which are arc-shaped surfaces, and the generatrix direction of the arc surface is parallel to the axis direction of the strip spring 1. When no external force is applied, the strip spring 1 remains in a straight and unfolded state. Under the action of a certain external force, the strip spring 1 undergoes buckling instability, achieving bending deformation perpendicular to the axis and from the concave surface to the convex surface, and transforming into a folded state.

[0039] like Figure 3 As shown, the flapping wing leading edge beam 2 is a three-dimensional structure, which is a slender beam. The cross section of the beam includes but is not limited to circular, rectangular, etc. This structure serves as the leading edge beam of the flapping wing, driving the flapping wing to perform reciprocating flapping motion;

[0040] like Figure 4 As shown, the fixing block 3 is a three-dimensional structure, and the main structure is a cylindrical structure. The main structure has four side surfaces, one of which is a cylindrical concave surface, and the other three side surfaces are flat surfaces; a through hole is punched at the bottom surface of the fixing block 3;

[0041] like Figure 5 As shown, the stop block 4 is a three-dimensional structure, and the main structure is a column structure. A through hole is punched on the side of the column, and the flapping wing leading edge beam 2 passes through the through hole and is fixed to the stop block 4; the bottom surface of the stop block 4 on the side connected to the strip spring 1 has an arc-shaped groove 401, which is consistent with the cross-sectional shape of the strip spring 1, so that the strip spring 1 and the stop block 4 are easily embedded; the other pair of side positions of the column have symmetrical bosses 402;

[0042] like Figure 6 As shown, the flapping wing root rotating part 5 is a three-dimensional structure, which is the output end component of the flapping wing aircraft transmission mechanism, and its rotational movement drives the flapping wing to flap back and forth; the lower side of the flapping wing root rotating part 5 is an inverted groove structure, and the bottom surface of the groove structure is a cylindrical convex surface 501, which fits with the concave surface of the strip spring 1; there is a through hole on each side close to the rotating axis, which is coaxial with the through hole of the fixed block 3, so that the fixed block 3 is matched with the groove structure; the position of the groove structure away from the rotating axis is a semi-open groove at the top, and the groove at this position cooperates with the stop block 4, and the outside of the groove has an end structure 502, which limits the stop block 4 from moving outward along the span direction of the flapping wing, and there is a groove structure at the end, and the groove width size matches the flapping wing leading edge beam 2, so that the flapping wing leading edge beam 2 passes through the stop block 4 and is embedded in the groove.

[0043] The retractable flapping-wing mechanism of the micro flapping-wing aircraft is characterized in that the concave surface on one side of the strip spring 1 fits with the convex surface of the groove structure of the flapping-wing root rotating part 5, and the convex surface on the other side of the strip spring 1 fits with the concave surface of the fixed block 3; the cooperation between the fixed block 3 and the flapping-wing root rotating part 5 limits the movement of the root of the strip spring 1 in the downward direction.

[0044] The retractable flapping-wing mechanism of the micro flapping-wing aircraft is characterized in that the material and geometric dimensions (such as length, central angle of cross-sectional arc, etc.) of the strip spring 1 should be matched through reasonable calculation and design to ensure that in the unfolded state, its bending stiffness can resist the torque generated by its own gravity, flapping wings and the weight of the stop block 4 without buckling instability; the material of the strip spring 1 includes but is not limited to stainless steel, medium carbon steel, high carbon steel, copper alloy, carbon fiber composite material, etc.

[0045] The retractable flapping-wing mechanism of the micro flapping-wing aircraft is characterized in that the installation position of the flapping-wing leading edge beam 2 should pass through the through hole of the stop block 4 when the strip spring 1 is in a straight state, and cooperate with the groove structure 502 at the end of the flapping-wing root rotating member 5 to maintain a horizontal state;

[0046] The method for implementing the retractable flapping-wing mechanism of a micro flapping-wing aircraft is characterized in that the strip spring 1 becomes buckled and unstable and bends downward under a certain external force, driving the stop block 4 and the flapping-wing leading edge beam 2 to retract downward to the side of the aircraft body, and the maximum bending angle is close to 90 degrees; when the external force is removed, the strain energy of the strip spring 1 is converted into mechanical energy, restored to a straight state, driving the stop block 4 and the flapping-wing leading edge beam 2 to unfold to a horizontal position, and the stop block 4 is embedded in the semi-open groove of the flapping-wing root rotating part 5; under the action of lift, the stop block 4 and the flapping-wing leading edge beam 2 are subjected to an upward force without generating downward movement; the symmetrical boss 402 of the stop block can play a limiting role, ensuring that the stop block 4 and the flapping-wing leading edge beam 2 will not move upward under the action of lift, thereby ensuring the subsequent flapping movement.

[0047] The installation method of the retractable flapping-wing mechanism of the micro flapping-wing aircraft is as follows:

[0048] (1) The strip spring 1 and the stop block 4 are interlocked and fixedly connected by bonding to prevent the stop block 4 from being separated from the strip spring 1; the adhesive used for bonding includes but is not limited to epoxy resin adhesive, acrylic adhesive, organic silicone adhesive, polyurethane adhesive, etc.;

[0049] (2) The stop block 4 is installed in the semi-open groove at the top of the flapping wing root rotating member 5 away from the rotation axis. At this time, the upper surface of the symmetrical boss 402 of the stop block 4 should be in contact with the lower surface of the corresponding side wall position of the flapping wing root rotating member 5 to limit the upward movement of the stop block 4;

[0050] (3) One end of the strip spring 1 near the rotation axis is fixedly connected to the fixed block 3 and the flapping wing root rotating member 5 by bonding, so as to limit the strip spring 1 from moving outward along the flapping wing span direction in a bent state; the through hole of the fixed block 3 is concentric with the side through hole of the flapping wing root rotating member 5 near the rotation axis, and can be connected and fixed by an axis pin;

[0051] (4) The stop block 4 is matched with the flapping wing leading edge beam 2 through a through hole and fixedly connected by bonding to limit the flapping wing leading edge beam 2 from being separated from the stop block 4. After the connection, the flapping wing leading edge beam 2 should be in a horizontal state; the bonding material is the same as that in step (1).

Claims

1. A retractable flapping-wing mechanism for a micro flapping-wing aircraft comprises a strip spring, a flapping-wing leading edge beam, a fixed block, a stop block, and a flapping-wing root rotating member; characterized in that: The strip spring is a three-dimensional structure with a certain thickness and an arc-shaped cross-section. The strip spring has a concave surface and a convex surface, both of which are arc-shaped surfaces, and the generatrix direction of the arc surface is parallel to the axis direction of the strip spring. When no external force is applied, the strip spring maintains a straight and unfolded state. Under the action of a certain external force, the strip spring undergoes buckling instability, achieving bending deformation perpendicular to the axis and from the concave surface to the convex surface, and transforming into a folded state. The flapping wing leading edge beam is a three-dimensional structure, which is a slender beam. This structure serves as the leading edge beam of the flapping wing, driving the flapping wing to perform reciprocating flapping motion; The fixing block is a three-dimensional structure, and the main structure is a cylindrical structure. The main structure has four side surfaces, one of which is a cylindrical concave surface, and the other three side surfaces are flat surfaces. A through hole is punched at the bottom surface of the fixing block. The stop block is a three-dimensional structure, and the main structure is a column structure. The column has a pair of side positions with through holes, and the flapping wing leading edge beam passes through the through holes and is fixedly connected to the stop block; the bottom surface of the stop block on the side connected to the strip spring has an arc-shaped groove, which is consistent with the cross-sectional shape of the strip spring, so that the strip spring and the stop block are embedded; the other pair of side positions of the column have symmetrical bosses; The flapping wing root rotating part is a three-dimensional structure, which is the output end component of the flapping wing aircraft transmission mechanism, and its rotational movement drives the flapping wing to flap back and forth; the lower side of the flapping wing root rotating part is an inverted groove structure, and the bottom surface of the groove structure is a cylindrical convex surface, which fits with the concave surface of the strip spring; there is a through hole on each side close to the rotating axis, which is coaxial with the through hole of the fixed block, so that the fixed block and the groove structure are matched; the position of the groove structure away from the rotating axis is a semi-open groove at the top, and the groove at this position cooperates with the stop block, and the outside of the groove has an end structure to limit the stop block from moving outward along the span direction of the flapping wing, and there is a groove structure at the end, and the groove width size matches the leading edge beam of the flapping wing, so that the leading edge beam of the flapping wing passes through the stop block and is embedded in the groove.

2. The retractable flapping-wing mechanism of a flapping-wing micro aircraft according to claim 1, wherein: The concave surface on one side of the strip spring fits with the convex surface of the groove structure of the flapping wing root rotating part, and the convex surface on the other side of the strip spring fits with the concave surface of the fixed block; the cooperation between the fixed block and the flapping wing root rotating part limits the movement of the root of the strip spring in the downward direction.

3. The retractable flapping-wing mechanism of a flapping-wing micro aircraft according to claim 1, wherein: The material and geometric dimensions of the strip spring should be matched through reasonable calculation and design to ensure that, in the unfolded state, its bending stiffness can resist the torque generated by its own gravity, flapping wings and the weight of the stop block without buckling instability; the material of the strip spring includes but is not limited to stainless steel, medium carbon steel, high carbon steel, copper alloy, carbon fiber composite material, etc.

4. The retractable flapping-wing mechanism of a flapping-wing micro aircraft according to claim 1, wherein: The installation position of the flapping wing leading edge beam should pass through the through hole of the stop block when the strip spring is in a straight state, and cooperate with the groove structure at the end of the flapping wing root rotating part to maintain a horizontal state.

5. A method for implementing a retractable flapping-wing mechanism of a micro flapping-wing aircraft according to any one of claims 1 to 4, characterized in that: Under the action of a certain external force, the strip spring becomes unstable and bends downward, driving the stop block and the flapping wing leading edge beam to retract downward to the side of the aircraft body; when the external force is removed, the strain energy of the strip spring is converted into mechanical energy, and it returns to a straight state, driving the stop block and the flapping wing leading edge beam to unfold to a horizontal position, and the stop block is embedded in the semi-open groove of the flapping wing root rotating part; under the action of lift, the stop block and the flapping wing leading edge beam are subjected to an upward force without generating downward movement, thereby ensuring the subsequent flapping movement of the flapping wing.

6. A method for installing a retractable flapping-wing mechanism of a flapping-wing micro aircraft according to any one of claims 1 to 4: (1) The strip spring and the stop block are fitted together and fixedly connected by bonding to prevent the stop block from separating from the strip spring; the adhesive used for bonding includes but is not limited to epoxy resin adhesive, acrylate adhesive, organic silicone adhesive, polyurethane adhesive, etc.; (2) The stop block is installed in the semi-open groove at the top of the flapping wing root rotating member away from the rotation axis. At this time, the upper surface of the symmetrical boss of the stop block should be in contact with the lower surface of the corresponding side wall position of the flapping wing root rotating member to limit the upward movement of the stop block; (3) One end of the strip spring close to the rotating shaft is fixedly connected to the fixed block and the flapping wing root rotating member by bonding, so as to limit the strip spring from moving outward along the flapping wing span direction in a bent state; the through hole of the fixed block is concentric with the side through hole of the flapping wing root rotating member close to the rotating shaft, and can be connected and fixed by a shaft pin; (4) The stop block is matched with the flapping wing leading edge beam through a through hole and fixedly connected by bonding to limit the flapping wing leading edge beam from being separated from the stop block. After the connection, the flapping wing leading edge beam should be in a horizontal state; the bonding material is the same as that in step (1).

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