Telescopic forked winglet structure of unmanned aerial vehicle and telescopic wing

Abstract

The invention provides a telescopic forked winglet structure of an unmanned aerial vehicle and a telescopic wing. The telescopic forked winglet structure comprises a wing surface device, a supporting device and a transmission device, the wing surface device comprises an upper winglet structure and a lower winglet structure, the supporting device can be arranged in a wing in a sliding mode along a front beam and a rear beam of the wing, the transmission device comprises a lead screw motor and a segmented lead screw, and the segmented lead screw is provided with an inner segment with the small diameter and an outer segment with the large diameter; the root parts of the upper winglet structure and the lower winglet structure are respectively hinged to the supporting device, and gears meshed with the outer section are fixedly connected to the root parts of the upper winglet structure and the lower winglet structure; the supporting device is provided with a screw hole matched with the inner section in a threaded mode. The lead screw motor drives the segmented lead screw to rotate, so that the supporting device moves in the axis direction of the segmented lead screw to drive the whole wing surface device to stretch out and draw back. And after the supporting device moves until the gear is meshed with the outer section, the outer section rotates to drive the upper small wing structure and the lower small wing structure to reversely deflect around respective hinge shafts to realize bifurcation. The pneumatic efficiency is improved while the space is saved.

Description

Technical Field

[0001] This invention relates to the field of aircraft structural design technology, and in particular to a telescopic bifurcated winglet structure and telescopic wing of an unmanned aerial vehicle (UAV). Background Technology

[0002] Winglets are used in subsonic aircraft, primarily including commercial airliners, military transport aircraft, aerial refueling tankers, early warning aircraft, and unmanned aerial vehicles (UAVs). Currently, some subsonic aircraft worldwide incorporate winglets to improve spanwise airflow, reduce induced drag, decrease fuel consumption, and enhance economic efficiency. However, not all subsonic aircraft use winglets. Firstly, cost and applicability are limited. Adding winglets significantly increases design and manufacturing costs; for example, the cost of adding winglets to a passenger aircraft can reach hundreds of thousands of dollars. Furthermore, winglets maximize fuel savings only during long-range cruise phases; their benefits are limited for short-range, multi-mission-switching flight scenarios. Secondly, they are vulnerable to damage and have high maintenance costs. Located at the wingtips, winglets are at higher risk of collision damage, and traditional winglets are difficult to disassemble, resulting in high repair costs if damaged. Thirdly, UAVs present unique challenges. Existing drones require separate motors to drive the winglets for angle adjustment or opening / closing, which increases the weight of the drone. In addition, some drones have non-retractable wings, which take up a lot of space during transportation and storage. Furthermore, when the wings are extended, they are less resistant to collisions and are easily broken, making the packaging process cumbersome.

[0003] Therefore, the design of subsonic aircraft requires comprehensive consideration when deciding whether to add winglets, especially in drones. The use of winglets necessitates a separate motor to drive them for angle adjustment or opening / closing, resulting in significant weight. Furthermore, some drones have non-retractable wings, which occupy considerable transport and storage space, making them inconvenient to transport and store. Additionally, the extended wings offer poor impact resistance during transport, posing a risk of breakage and requiring careful and cumbersome packaging.

[0004] Therefore, it is necessary to study a telescopic bifurcated winglet structure and telescopic wing for unmanned aerial vehicles to address the shortcomings of existing technologies and solve or mitigate one or more of the aforementioned problems. Summary of the Invention

[0005] In view of this, the present invention provides a retractable and forked winglet structure and a retractable wing for a drone, which realizes the retractability and forked opening and closing of the winglet, thereby saving space, improving aerodynamic efficiency, simplifying the structure to reduce weight and improve reliability.

[0006] On one hand, the present invention provides a retractable forked winglet structure for a drone, the retractable forked winglet structure for a drone includes a wing surface device, a support device and a transmission device; The wing assembly includes an upper winglet structure and a lower winglet structure. The support device can be slidably installed inside the wing along the front and rear wing spars. The transmission device includes a lead screw motor and a segmented lead screw, the segmented lead screw having an inner section with a smaller diameter and an outer section with a larger diameter; the roots of the upper wing structure and the lower wing structure are respectively hinged to the support device, and the roots of the upper wing structure and the lower wing structure are fixedly connected to gears that mesh with the outer section; The support device is provided with a threaded hole that mates with the inner section thread; the lead screw motor drives the segmented lead screw to rotate, causing the support device to move along the axis of the segmented lead screw to drive the wing device to extend and retract as a whole; after the support device moves to the point where the gear meshes with the outer section, the outer section rotates to drive the upper wing structure and the lower wing structure to deflect in opposite directions around their respective hinge axes to achieve bifurcation.

[0007] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the support device includes a slider, an upper connector, and a lower connector. The upper connector and the lower connector are fixed to the side of the slider and are respectively located above and below the screw hole. The root of the upper winglet structure is hinged to the upper connector via a pivot, and the root of the lower winglet structure is hinged to the lower connector via a pivot. The slider is guided by the wing's fore and aft spars. The middle of the slider is provided with the through screw hole that continuously engages with the inner section. The upper winglet structure and the lower winglet structure are initially housed parallel and fitted inside the wing.

[0008] In addition to the aspects and any possible implementations described above, a further implementation is provided, wherein the segmented lead screw includes: an inner section that is threadedly engaged with a screw hole of the support device to enable the support device to translate axially; an outer section disposed at one end of the segmented lead screw near the wingtip and having a diameter larger than that of the inner section; the surface of the outer section is provided with a transmission structure that meshes with the gear; during the movement of the support device toward the wingtip, the inner section remains engaged with the screw hole while the gear does not contact the inner section.

[0009] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the root gears of the upper winglet structure and the lower winglet structure include: the gears are fixed to their respective roots and arranged around a hinge axis; the gears engage with the outer segment only after the support device moves to a predetermined position; when the outer segment rotates, it drives the upper winglet structure to deflect upward by engaging with the gears; when the outer segment rotates, it drives the lower winglet structure to deflect downward by engaging with the gears; the upper winglet structure and the lower winglet structure deflect in opposite directions to form a bifurcated state.

[0010] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the lead screw motor is fixedly installed inside the wing and is fixed relative to the fore and aft spar of the wing; the segmented lead screw passes through the lead screw motor and is driven by the lead screw motor to rotate continuously; the lead screw motor is located on the side of the support device's range of motion close to the wing root; the unidirectional rotation of the lead screw motor sequentially realizes the extension of the wing surface device and the bifurcation and deployment of the upper winglet structure and the lower winglet structure.

[0011] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the upper joint includes two spaced-apart protruding structures to engage with the root pivot of the upper winglet structure to form a hinge, and the lower joint includes two spaced-apart protruding structures to engage with the root pivot of the lower winglet structure to form a hinge; there is no direct connection between the upper winglet structure and the lower winglet structure; and the support device slides stably along the fore and aft spars of the wing via the slider.

[0012] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the outer segment and the inner segment are coaxially connected to form a stepped diameter transition, and the transmission structure of the outer segment includes a worm gear or rack segment to mesh with the gear; the segmented lead screw first completes the axial displacement of the support device through the inner segment in a single rotation direction; the segmented lead screw continues to rotate so that the outer segment enters the meshing area with the gear to achieve bifurcated drive.

[0013] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the UAV retractable forked winglet structure is integrated into the retractable wing. In the retracted state, the retractable wing completely houses the wing surface device inside the wing. In the extended forked state, the retractable wing increases the effective aspect ratio of the wing through the upper winglet structure and the lower winglet structure. The screw motor rotates in the opposite direction to achieve the closing of the upper winglet structure and the lower winglet structure before retracting them as a whole.

[0014] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the lead screw motor is a DC brushless motor equipped with a reduction gear and an output torque of not less than 5 N·m.

[0015] In addition to the aspects described above and any possible implementation, a retractable wing for unmanned aerial vehicles (UAVs) is further provided, the retractable wing for unmanned aerial vehicles (UAVs) including a wing body and a retractable forked winglet structure, the retractable forked winglet structure being retractable inside the wing body or extending along the span of the wing body.

[0016] Compared with the prior art, the present invention can achieve the following technical effects: This invention combines a telescopic wing with a winglet, and designs a telescopic and retractable winglet to increase the effective aspect ratio and reduce induced drag. When the winglet is retracted, the wingspan is small, saving spanwise space. During flight, the spanwise space is not limited, and the winglet can be extended to increase the aspect ratio and improve flight stability. This invention uses a segmented lead screw, thereby enabling a single motor to simultaneously control the extension and retraction of the winglets, simplifying the mechanism, reducing weight, and increasing the number of motors, which in turn improves overall reliability. Compared to fixed winglets, the retractable winglets of this invention save more space; Compared to non-split winglets, this invention features a split winglet that, by forming two surfaces—upward and downward—simultaneously handles airflow from both sides. This allows it to more comprehensively smooth out the complex vortex field at the wingtip, resulting in higher efficiency in reducing induced drag. This is equivalent to simultaneously "catching" the airflow from two directions, leading to less energy loss. Compared to existing technologies, this invention uses only one motor to drive the worm gear to rotate. By utilizing the rotation of the stepped worm gear, the movement and bifurcation of the winglet can be achieved simultaneously, without the need to add another motor to control the bifurcation of the winglet.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a longitudinal cross-sectional view of a telescopic bifurcated winglet structure provided in one embodiment of the present invention; Figure 2This is a partially enlarged view of a telescopic bifurcated winglet structure provided in one embodiment of the present invention; Figure 3 This is a transverse cross-sectional view of a telescopic bifurcated winglet structure provided in one embodiment of the present invention; Figure 4 This is a diagram showing the extended, unbranched state of a telescopic forked winglet structure provided in one embodiment of the present invention; Figure 5 This is a top view of the extended, unbranched state of a telescopic forked winglet structure provided in an embodiment of the present invention; Figure 6 This is a front view of the extended, unbranched state of a telescopic forked winglet structure provided in an embodiment of the present invention; Figure 7 This is a diagram of the fully retracted state of a telescopic bifurcated winglet structure provided in one embodiment of the present invention; Figure 8 This is a left view of the fully retracted state of a telescopic bifurcated winglet structure provided in an embodiment of the present invention; Figure 9 This is a top view of the fully retracted state of a telescopic bifurcated winglet structure provided in an embodiment of the present invention; Figure 10 This is a front view of the fully extended and bifurcated state of a telescopic bifurcated winglet structure provided in an embodiment of the present invention; Figure 11 This is a top view of the fully extended and bifurcated state of a telescopic bifurcated winglet structure provided in an embodiment of the present invention; Figure 12 This is a structural diagram of a support device provided in one embodiment of the present invention; Figure 13 This is an overall positional relationship diagram provided in one embodiment of the present invention. Detailed Implementation

[0020] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0023] This invention provides a retractable and forked winglet structure for unmanned aerial vehicles (UAVs). This structure, through an innovative segmented screw drive mechanism, achieves the dual functions of winglet retraction and forking, significantly improving the aerodynamic performance of the UAV in different flight states. This technical solution is particularly suitable for UAV platforms that need to frequently switch between cruise and maneuvering flight, optimizing lift-to-drag ratio and handling performance by dynamically adjusting the winglet's geometry.

[0024] In step S1, the lead screw motor drives the segmented lead screw to rotate, causing the support device to move along the axis of the segmented lead screw, thereby driving the overall extension and retraction of the airfoil device. In this step, the lead screw motor serves as the power source for the entire system, achieving linear displacement of the airfoil device through precise rotation control. The lead screw motor adopts a stepper motor or servo motor structure, possessing high-precision position control capabilities and sufficient output torque. The motor internally includes stator windings and rotor magnetic poles, generating rotational torque through the principle of electromagnetic induction. When the control system sends a pulse signal to the motor, the motor rotates according to a preset step angle or continuous angle, with a rotation accuracy within 0.1 degrees.

[0025] The segmented lead screw design is one of the core innovations of this technical solution. The segmented lead screw consists of two parts: an inner section and an outer section. The inner section has a smaller diameter and a standard thread structure, while the outer section has a larger diameter and transmission teeth on its surface. The thread parameters of the inner section include pitch, thread angle, and thread depth, which directly affect the moving speed and transmission accuracy of the support device. For example, when the inner section pitch is set to 2 mm, the support device moves 2 mm axially for every revolution of the lead screw motor. The thread angle of the inner section typically adopts a standard 60-degree angle to ensure a good fit with the threaded hole of the support device. The thread depth is controlled between 0.5 and 1 mm to ensure transmission strength while reducing frictional resistance.

[0026] The support device achieves precise axial movement driven by a segmented lead screw. The support device contains threaded holes that precisely mate with the inner thread of the lead screw section. The machining accuracy of these threaded holes directly affects transmission efficiency and positioning accuracy. The threaded holes are precision-machined using CNC machine tools, with a surface roughness controlled within 1.6 micrometers to ensure a smooth fit with the inner thread. When the lead screw motor drives the segmented lead screw to rotate, the support device is forced to move axially due to the threaded engagement between the inner section and the threaded hole. During this movement, the support device is guided by the front and rear wing spars to ensure the straightness and stability of the movement trajectory.

[0027] In one embodiment, the speed of the lead screw motor is controlled between 100 and 500 revolutions per minute, corresponding to a moving speed of 3 to 15 millimeters per second for the support device. This moving speed ensures both the smooth extension and retraction of the wing device and meets the needs of rapid adjustment during UAV flight. The motor speed is precisely controlled via pulse width modulation signals, with a control accuracy within 1% of the set speed value. When rapid deployment of the wing device is required, the motor operates at a higher speed. When precise positioning is required, the motor operates at a lower speed to ensure that the support device accurately reaches the predetermined position.

[0028] The wing assembly comprises an upper winglet structure and a lower winglet structure, both of which move synchronously via a support system. Initially, both structures are retracted and completely within the wing. In the retracted state, the upper winglet structure lies on the inner side of the upper wing surface, and the lower winglet structure lies on the inner side of the lower wing surface, parallel and fitted together to minimize space occupation. A dedicated retraction slot is provided inside the wing, its geometry precisely matching the shape of the winglet structure to ensure stability and sealing during retraction.

[0029] As the support structure begins to move towards the wingtip, the upper and lower winglets move as a whole. During this movement, the winglets maintain their initial parallel state and do not rotate relative to each other. This integrated movement ensures the stability of the wing structure during extension and avoids unbalanced moments caused by individual movement. The movement distance of the support structure is typically set between 50 and 200 millimeters, with the specific value determined based on the UAV's wingspan and design requirements.

[0030] In step S2, after the support device moves to the point where the gear meshes with the outer section, the rotation of the outer section drives the upper and lower wing structures to deflect in opposite directions around their respective hinge axes, thus achieving bifurcation. This step is the most critical and innovative part of the entire technical solution, achieving the conversion from linear motion to rotational motion through ingenious timing control. When the support device moves to the predetermined position, the gears fixed to the roots of the upper and lower wing structures begin to mesh with the outer section of the segmented lead screw.

[0031] The meshing of the gear with the outer section is a gradual process. The surface of the outer section is equipped with helical transmission teeth, the helix angle and tooth pitch of which are precisely calculated to ensure smooth meshing with the gear. When the gear first contacts the outer section, only a portion of the tooth surface is engaged. As the support device continues to move, the meshing area gradually increases until full engagement is achieved. This gradual meshing method effectively reduces impact loads and improves the reliability of the transmission system.

[0032] In one embodiment, the diameter of the outer section is set to 1.5 to 2 times the diameter of the inner section. This diameter difference not only provides space for gear meshing but also increases the transmission torque. The transmission teeth on the surface of the outer section adopt an involute tooth profile, with a module set between 1 and 3 millimeters. The number of teeth on the gear is typically 12 to 24, and the fit with the teeth on the outer section ensures an appropriate transmission ratio. When the outer section rotates one revolution, the angle of rotation of the gear is determined according to the tooth ratio and is typically designed to deflect the winglet structure by 30 to 90 degrees.

[0033] The roots of the upper and lower winglets are connected to the support structure via hinge shafts. These hinge shafts are made of high-strength alloy steel and have undergone surface hardening treatment to improve wear resistance. The diameter of the hinge shaft is typically between 5 and 15 mm, and the length is determined based on the width of the winglet structure. The connection between the hinge shaft and the support structure uses a bearing structure; the inner ring of the bearing is interference-fitted with the hinge shaft, and the outer ring is fitted with the joint portion of the support structure. The bearings are deep groove ball bearings or angular contact ball bearings, providing good radial and axial load capacity.

[0034] When the outer section begins to rotate, it drives the upper and lower winglets to rotate around their respective hinge axes via gear transmission. The gears in the upper winglet are designed to deflect upwards, while those in the lower winglet are designed to deflect downwards; their deflection directions are opposite, creating a forked state. This reverse deflection is achieved through different gear mounting orientations: the gears in the upper winglet are mounted clockwise, and those in the lower winglet are mounted counterclockwise, or through different gear tooth profile designs to achieve reverse transmission.

[0035] The bifurcation angle is controlled by a limiting mechanism. Limit blocks or grooves are installed on the support device; when the winglet structure deflects to a predetermined angle, the limiting mechanism prevents it from rotating further. The bifurcation angle is typically set between 30 and 90 degrees, with the specific angle determined based on aerodynamic performance requirements. Smaller bifurcation angles are suitable for high-speed cruise, while larger bifurcation angles are suitable for low-speed maneuvers. The limiting mechanism also has a buffering function, absorbing the impact energy upon deflection through elastic elements.

[0036] Step S21: The slider has a through-hole in the middle that engages with the continuous thread in the inner section. As the core component of the support device, the slider performs the dual functions of transmitting power and supporting the wing surface. The slider is made of high-strength aluminum alloy or titanium alloy, possessing the characteristics of being lightweight and high-strength. The overall shape of the slider is a cuboid or cylinder, with a length typically between 80 and 150 mm, and the width and height determined according to the internal space of the wing.

[0037] The threaded hole in the middle of the slider is a key component of the entire transmission system. The machining accuracy of the threaded hole directly affects the transmission efficiency and system reliability. The threaded hole is machined using CNC thread milling or thread grinding processes, achieving a thread accuracy grade of 6H or higher. The inner diameter of the threaded hole forms a standard threaded fit with the outer diameter of the inner section of the segmented lead screw, with the fit clearance controlled between 0.05 and 0.15 mm. This precision fit ensures the accuracy of the transmission while reducing transmission backlash and return error.

[0038] The thread parameters of the threaded hole are perfectly matched with the inner section, including pitch, thread angle, and thread depth. The thread surface is precision polished, with a surface roughness controlled within 0.8 micrometers, and coated with a special thread lubricant to reduce friction and wear. The lubricant is a high-temperature, high-pressure grease with excellent oxidation and wear resistance, maintaining stable lubrication performance within a temperature range of -40 to +80 degrees Celsius.

[0039] In one embodiment, the length of the threaded hole is set to 30 to 60 mm to ensure sufficient engagement length with the inner section. A longer engagement length improves transmission stability and load-bearing capacity, but also increases frictional resistance. By optimizing thread parameters and lubrication conditions, frictional losses are minimized while ensuring transmission performance. Chamfers are provided at both ends of the threaded hole to facilitate insertion of the inner section and reduce stress concentration.

[0040] The slider engages with the wing's fore and aft spars using a sliding guide mechanism. The fore and aft spars act as guide rails, providing precise guidance and support for the slider. Guide grooves or guide surfaces are provided on the sides of the slider, forming a sliding engagement with the guide surfaces of the wing spars. The guide surfaces are made of wear-resistant materials or have surface treatments such as PTFE coating or hard anodizing to reduce sliding friction and wear.

[0041] In step S22, the upper and lower winglets are initially stowed parallel to each other inside the wing. This initial stowage design is crucial for ensuring the UAV maintains a good aerodynamic shape when not in operation. When stowed, the upper and lower winglets are completely hidden inside the wing, without affecting the wing's external profile or aerodynamic performance.

[0042] The wing incorporates a dedicated storage chamber, its geometry precisely matching the shape of the winglet structure. The inner walls of this chamber are lined with flexible materials, such as foam rubber or fiber felt, to protect the winglet structure surface from damage. The chamber is well-sealed to prevent external airflow from affecting the winglet's stability. The chamber cover uses the same material and surface treatment as the wing skin to ensure visual consistency.

[0043] The relative positions of the upper and lower winglets in the retracted state are precisely designed. They fit parallel to each other, with a gap between 1 and 3 millimeters, avoiding interference and minimizing space occupation. The leading and trailing edges of the winglets are parallel to the leading and trailing edges of the wing, ensuring geometric harmony in the retracted state.

[0044] The folded winglet is secured using a locking mechanism. This mechanism includes a spring-loaded pin or a magnetic latch, which automatically locks when the winglet is fully retracted, preventing accidental movement during flight. Unlocking is achieved via electromagnetic or mechanical actuation. When the winglet needs to be deployed, the control system first unlocks the locking mechanism and then activates the lead screw motor for the extension / retraction operation.

[0045] Step S31: The outer section surface is provided with a transmission structure that meshes with the gear. The design of the transmission structure of the outer section is a key technical aspect in realizing the conversion from linear motion to rotary motion. The transmission structure adopts helical tooth patterns or worm gear tooth profiles, which are helically distributed along the outer section surface. The choice of helical angle directly affects the transmission ratio and transmission efficiency, and is usually set between 15 and 45 degrees.

[0046] The design parameters for helical gear teeth include tooth pitch, tooth height, and tooth width. The tooth pitch is matched to the gear module to ensure good meshing performance. The tooth height is controlled between 1 and 3 mm to ensure sufficient transmission strength while avoiding excessive meshing resistance. The tooth width accounts for 60% to 80% of the tooth pitch, providing sufficient contact area. The tooth profile adopts an involute or cycloidal shape, possessing good transmission characteristics and low contact stress.

[0047] In one embodiment, the transmission structure on the outer surface employs a multi-start helical design, meaning that 2 to 4 parallel helical teeth are arranged on the outer surface. The multi-start helical design increases the number of teeth meshing simultaneously, improving transmission smoothness and load-bearing capacity. The phase difference between each helical tooth is evenly distributed, ensuring torque balance during transmission.

[0048] The transmission structure is machined using CNC spiral milling or gear hobbing. Machining accuracy reaches level 7 or higher, with tooth surface roughness controlled within 1.6 micrometers. The tooth surface undergoes hardening treatment, such as carburizing and quenching or nitriding, achieving a surface hardness of HRC50 or higher, improving wear resistance and service life. The transmission structure is also coated with a special gear grease to reduce meshing friction and noise.

[0049] In step S32, during the movement of the support device towards the wingtip, the inner section remains engaged with the screw hole while the gear does not contact the inner section. This design ensures the sequential separation of the extension and splitting actions, avoiding action conflicts and mechanism interference. In the initial stage of the support device's movement, a certain radial clearance is maintained between the gear and the inner section, preventing contact.

[0050] The radial clearance between the inner section and the gear is a key technical parameter. Too little clearance can lead to accidental contact and interference, while too much clearance affects the accuracy of subsequent meshing. The radial clearance is typically set between 2 and 5 millimeters, with the specific value determined based on the gear's outer diameter and the inner section's diameter. Clearance control is ensured through precise geometric design and machining accuracy.

[0051] During the movement of the support device, the inner section maintains a continuous threaded engagement with the screw hole. This continuous engagement ensures the accuracy and stability of the support device's movement. The thread length of the inner section is designed to be 1.2 to 1.5 times the maximum moving distance of the support device, ensuring sufficient thread engagement length throughout the entire movement. Variations in the thread engagement length do not affect transmission accuracy, but they do affect load-bearing capacity; therefore, the strength requirements at the minimum engagement length must be considered during the design phase.

[0052] In step S41, the outer section rotates, driving the upper winglet structure to deflect upwards through meshing with the gear. This step realizes the conversion process of the winglet from linear motion to rotational motion. After the transmission teeth on the surface of the outer section mesh with the gear at the root of the upper winglet structure, the rotational motion of the outer section is converted into the deflection motion of the upper winglet structure through gear transmission. During the transmission process, for each revolution of the outer section, the gear drives the upper winglet structure to deflect at a certain angle, and the deflection angle is determined by the number of teeth on the gear and the helix angle of the outer section's teeth.

[0053] In one embodiment, the outer section employs a multi-headed helical tooth design, with each tooth having a helix angle of 30 degrees. When the outer section rotates, the helical teeth push the gear teeth, generating a tangential force that causes the gear to rotate. The upper winglet structure's gear has 16 teeth and a module of 2 millimeters. For each rotation of the outer section, the gear deflects by 22.5 degrees. By controlling the number of rotations of the outer section, the deflection angle of the upper winglet structure can be precisely controlled. The deflection angle range is typically set between 0 and 90 degrees and can be adjusted according to flight requirements.

[0054] The deflection motion of the upper winglet structure is achieved via a hinged shaft. The hinged shaft is made of high-strength alloy steel, 10 mm in diameter, and undergoes carburizing and quenching treatment to achieve a hardness of HRC55. Both ends of the hinged shaft are supported at the upper joint of the support device by angular contact ball bearings (7200 series), capable of withstanding combined radial and axial loads. The hinged shaft is keyed to the root of the upper winglet structure to ensure effective transmission of torque.

[0055] During deflection, the aerodynamic shape of the upper winglet remains stable. The winglet features a rounded leading edge and a straight trailing edge, with an aspect ratio controlled between 3 and 5. The winglet surface is covered with an aerospace-grade aluminum alloy skin, 1.2 mm thick, and internally reinforced with ribs. During deflection, the winglet maintains overall rigidity and does not undergo torsional deformation. An anti-icing device is installed on the leading edge of the winglet to prevent icing in low-temperature environments from affecting deflection performance.

[0056] In step S42, when the outer section rotates, it drives the lower winglet structure to deflect downwards through meshing with the gear. This step is symmetrical to the deflection process of the upper winglet structure, but the deflection direction is opposite. The gear of the lower winglet structure is installed in the opposite direction to that of the upper winglet structure, ensuring that reverse deflection is achieved in the same rotation direction of the outer section. The tooth profile parameters of the gear are the same as those of the upper winglet structure, but the installation phases are 180 degrees apart.

[0057] The deflection mechanism design of the lower winglet is similar to that of the upper winglet, but there are some differences in details. The hinge shaft of the lower winglet has a slightly larger diameter, typically 12 mm, to withstand greater aerodynamic loads. The hinge bearing uses a double-row angular contact ball bearing, model 7300, which has a higher load-bearing capacity. The connection between the hinge shaft and the root of the lower winglet uses a spline structure to improve torque transmission.

[0058] In one embodiment, the lower winglet structure has the same deflection angle range as the upper winglet structure, but the initial deflection direction is opposite. When the outer section begins to rotate, the gear of the lower winglet structure experiences a tangential force opposite to that of the gear of the upper winglet structure, generating a reverse rotational torque. During the deflection process, the motion trajectory of the lower winglet structure is symmetrical to that of the upper winglet structure, forming a mirror image relationship. This symmetrical design ensures the aerodynamic balance of the UAV during the bifurcation process.

[0059] The aerodynamic characteristics of the lower winglet differ from those of the upper winglet. The lower winglet has a slightly larger aspect ratio, typically 10% to 20% larger than the upper winglet, to compensate for the ground effect. The leading edge sweep angle of the lower winglet is 5 degrees smaller than that of the upper winglet, improving lift characteristics at low speeds. The winglet surface is coated with a wear-resistant coating to prevent abrasion from ground debris during takeoff and landing. A reinforcing frame is installed internally in the winglet to increase structural rigidity.

[0060] In step S43, the upper and lower winglets deflect in opposite directions to form a bifurcated state. This step achieves the final working configuration of the winglets, significantly increasing the effective aspect ratio of the wing through the bifurcated arrangement of the upper and lower winglets. In the bifurcated state, the upper winglet deflects upward, and the lower winglet deflects downward, with the angle between them typically between 60 and 120 degrees, adjusted according to the flight conditions.

[0061] The formation of the bifurcation state is a gradual process. In the initial stage, the upper and lower winglets begin to deflect simultaneously at a consistent speed. As the deflection angle increases, the aerodynamic torque on the winglets gradually increases, and the load on the transmission system also increases accordingly. The control system monitors the changes in motor current and speed in real time to ensure the synchronicity and stability of the deflection process. When the preset deflection angle is reached, the limit mechanism activates to prevent the winglets from deflecting further.

[0062] In one embodiment, the bifurcation angle is controlled by position sensors. Angle sensors are installed at the roots of the upper and lower winglets to monitor the deflection angle in real time. The sensors use non-contact magnetic encoders with a resolution of 0.1 degrees. When the actual angle reaches the set value, the control system stops the motor and locks the winglet position. The locking mechanism uses an electromagnetic brake with a braking torque of up to 50 Nm to ensure the stability of the winglet position during flight.

[0063] Optimizing aerodynamic performance in the bifurcated configuration is a key design focus. The bifurcation angles of the upper and lower winglets were determined through aerodynamic calculations and wind tunnel testing, with different bifurcation angles employed at different flight speeds. A larger bifurcation angle is used at low speeds to improve lift characteristics, while a smaller bifurcation angle is used at high speeds to reduce induced drag. The relationship between the bifurcation angle and flight speed is automatically adjusted by the flight control system to achieve optimal aerodynamic performance.

[0064] In step S51, the lead screw motor is located on the side of the support device's range of motion near the wing root. This arrangement optimizes the space utilization efficiency of the transmission system. The lead screw motor is installed inside the wing near the fuselage and connected to the segmented lead screw via a coupling. The motor mounting base is made of cast magnesium alloy, which is lightweight and high-strength. The mounting base is secured to the wing frame with four M8 bolts to ensure transmission stability.

[0065] The positioning accuracy of the motor directly affects the performance of the entire system. The parallelism between the motor's mounting position and the wing's fore and aft spars is controlled within 0.1 mm, and the coaxiality with the segmented lead screw is controlled within 0.05 mm. A special fixture is used for positioning during installation to ensure that the motor axis coincides with the segmented lead screw axis. A flexible coupling is used to connect the motor output shaft and the segmented lead screw to compensate for minor coaxiality errors.

[0066] In one embodiment, the motor is mounted 150 to 200 millimeters from the wing root, the specific distance depending on the wing size. This arrangement places the motor in the area of ​​greatest wing structural rigidity, reducing the impact of wing deformation during flight on the transmission system. Heat dissipation channels are provided around the motor for cooling using airflow during flight. Heat dissipation fins are provided on the surface of the motor housing to increase the heat dissipation area.

[0067] The motor's electrical connections utilize aviation-grade connectors. Power and signal lines are laid out separately to avoid interference. The power lines have a cross-sectional area of ​​2.5 square millimeters and use silver-plated copper cores to improve conductivity. The signal lines use twisted-pair shielded cables to prevent electromagnetic interference. All cables are protected by fire-resistant conduits, meeting aircraft fire safety requirements. The connectors employ a self-locking structure to ensure they do not come loose during flight.

[0068] In step S52, the lead screw motor rotates in one direction to sequentially extend the wing device and split the upper and lower winglets. This design simplifies the control system, achieving two continuous actions through a single motor and a single direction of rotation. When the motor rotates clockwise, it first drives the support device to move outward, extending the wing device; once the support device reaches the predetermined position, continued rotation drives the upper and lower winglets to split and unfold.

[0069] The timing of the actions is controlled through a mechanical structure, eliminating the need for additional electronic control. The inner section of the segmented lead screw is designed to be 1.1 times the maximum travel distance of the support device, ensuring that the inner section remains engaged with the screw hole until the support device reaches the outer section's engagement position. The starting position of the outer section is precisely calculated so that the gears begin to engage exactly when the support device has moved into position. This mechanical timing control offers high reliability and is unaffected by electronic systems.

[0070] In one embodiment, the motor speed is set to 300 revolutions per minute. The first 30 seconds drive the support device to move, completing the extension of the winglet; the next 20 seconds drive the upper and lower winglets to fork and unfold, the entire process taking approximately 50 seconds. The speed is precisely controlled by the motor driver, ensuring smooth acceleration and deceleration and avoiding impact loads. The motor is equipped with an encoder to provide real-time feedback of speed and position information, forming a closed-loop control system.

[0071] The advantage of the unidirectional rotation design lies in its simplified control system. The entire deployment process can be completed without changing the motor's direction, reducing the complexity of the control logic. Simultaneously, the retraction action is automatically executed during reverse rotation, first closing the forked winglets and then retracting the wing surface assembly. This design is particularly suitable for UAV applications requiring frequent deployment and retraction, improving system reliability and responsiveness.

[0072] In step S61, there is no direct connection between the upper and lower winglet structures. This design ensures that they can deflect independently without interfering with each other. The upper and lower winglet structures are completely separated, connected to the support device only at their roots via their respective hinge shafts. This separate design reduces structural weight, improves transmission efficiency, and avoids mutual motion interference.

[0073] The upper and lower winglets have similar but independent structures. Each winglet has its own skin, frame, and reinforcing structure. The winglet frame uses an aluminum alloy truss structure, which is lightweight and high-strength. The skin is a composite laminate with a thickness of 0.8 mm. The winglet's interior has three main beams and several ribs, forming a stable load-bearing structure. The structural parameters of the upper and lower winglets are optimized separately according to the aerodynamic loads they bear.

[0074] In one embodiment, the upper winglet has a span 1.2 times that of the lower winglet to optimize aerodynamic performance at different positions. The upper winglet has a leading-edge sweep angle of 25 degrees, and the lower winglet has a leading-edge sweep angle of 20 degrees. This differentiated design allows the upper and lower winglets to achieve optimal aerodynamic performance under various flight conditions. Micro-control surfaces are provided on the trailing edges of the winglets for minor adjustments, further optimizing aerodynamic characteristics.

[0075] The design without direct connections simplifies maintenance. The upper and lower winglets can be disassembled and replaced individually, eliminating the need for overall disassembly and reassembly. Maintenance simply requires loosening the hinge shaft's fixing bolts to remove individual winglets for repair or replacement. This modular design reduces maintenance costs and improves system availability. Furthermore, damage to one winglet does not affect the function of another, enhancing the system's fault tolerance.

[0076] In step S62, the support device slides stably along the front and rear wing spars via a slider to ensure alignment during wing extension and retraction. This design guarantees the straightness and stability of the wing device during extension and retraction. The slider and the front and rear wing spars use a precision sliding pair, with the clearance controlled between 0.1 and 0.2 mm. The slider is made of wear-resistant bronze alloy, and the sliding surface of the wing spars is hard chrome plated to reduce the coefficient of friction.

[0077] The guide structure design of the slider is crucial. Guide grooves are provided on both sides of the slider, precisely matching the guide edges of the wing's fore and aft spars. The width of the guide groove is 0.15 mm larger than the guide edge, ensuring smooth sliding without excessive clearance. The length of the guide groove is 20% longer than the slider's stroke, ensuring guidance throughout the entire travel. The surface roughness of the guide surface is controlled within 0.4 micrometers, and it is lubricated with a special grease.

[0078] In one embodiment, the slider is 120 mm long, 80 mm wide, and 40 mm high. Two parallel threaded holes are provided inside the slider, each engaging with the inner section of a segmented lead screw. Limit buffers made of polyurethane material are provided at both ends of the slider to absorb impact energy during positioning. The slider weight is controlled to be less than 300 grams to reduce motion inertia.

[0079] Measures to ensure slip stability include: regular lubrication and maintenance of the guide surface; selection of wear-resistant slider materials; precise control of clearance; and vibration monitoring during operation. Before flight, the slider's movement resistance must be checked to ensure it is within the normal range. During flight, vibration sensors monitor the slider's movement, and alarms are triggered promptly upon detecting abnormalities. These measures collectively ensure the stable and reliable extension and retraction of the wing assembly.

[0080] In step S71, the segmented lead screw completes the axial displacement of the support device first through the inner section in a single rotation direction. This design achieves automatic switching between two continuous actions. The thread parameters of the inner section are precisely calculated to ensure that the outer section will not contact the gear before the support device moves into position. The length of the inner section is equal to the maximum travel distance of the support device plus a safety margin, which is typically 10 mm.

[0081] The inner section features a trapezoidal thread with a 30-degree thread angle and a 4-mm pitch. This thread offers high transmission efficiency and load-bearing capacity. The thread surface is precision ground to a roughness of 0.8 micrometers and coated with molybdenum disulfide lubricant. The fit clearance between the inner section and the threaded hole is 0.1 mm, ensuring precise transmission without excessive friction. A 15-degree guide taper is provided at the end of the inner section for easy assembly.

[0082] In one embodiment, the inner section has a diameter of 12 mm and a length of 150 mm. When the motor rotates at a speed of 300 revolutions per minute, the support device moves at a speed of 20 mm / s, completing the full stroke in 7.5 seconds. During the movement, the motor current is monitored in real time. An abnormal increase in current indicates a possible obstacle, and the control system immediately stops the motor to prevent damage to the mechanism.

[0083] Precise control of axial displacement is ensured through multiple measures: thread machining accuracy reaches 6g level; the clearance of the guide system is strictly controlled; the motor is equipped with a high-resolution encoder; and the control system employs a closed-loop algorithm. These measures together ensure that the support device can accurately reach the predetermined position, creating accurate spatial conditions for subsequent bifurcation actions.

[0084] In step S72, the segmented lead screw continues to rotate, causing the outer segment to enter the meshing area with the gear, thus achieving bifurcated drive. This step marks the turning point where the mechanism transitions from linear motion to rotational motion. The initial position of the outer segment is precisely calculated to ensure that the gear begins to engage just as the support device moves into place. The transition area between the outer and inner segments uses a rounded transition to reduce stress concentration.

[0085] The outer meshing area is typically 30 to 50 mm long to ensure sufficient engagement length for torque transmission. The surface hardness of the meshing area is HRC58 or higher, providing good wear resistance. High-quality alloy steel is used for the gear material, with carburizing and quenching treatment on the tooth surface. High-temperature grease is used for lubrication of the meshing area, with an operating temperature range of -50 to 150 degrees Celsius. The meshing clearance is controlled between 0.05 and 0.1 mm.

[0086] In one embodiment, the outer section has a diameter of 20 mm, which is 8 mm larger than the inner section, providing sufficient space for gear meshing. The outer section surface is machined with double-ended helical teeth with a helix angle of 45 degrees. When the outer section begins to mesh with the gear, the initial contact force is small, and the transmission torque gradually increases with the increase of the meshing depth. This progressive meshing method reduces impact and extends the life of the mechanism.

[0087] Monitoring of the bifurcation drive process includes: motor current monitoring to reflect the transmission load; angle sensor monitoring to provide real-time feedback on the deflection angle; and temperature sensor monitoring to prevent overheating. When any parameter exceeds the normal range, the control system automatically stops the motor and issues an alarm. This multi-layered protection mechanism ensures the safety and reliability of the bifurcation drive process.

[0088] In step S81, the lead screw motor rotates in the reverse direction to achieve the initial closure and subsequent retraction of the upper and lower winglets. This process is the reverse of the deployment process, but it is also achieved through the rotation of a single motor. When the motor rotates counterclockwise, it first drives the outer section to reverse, causing the upper and lower winglets to close from their bifurcated state; once the winglets are fully closed, continued rotation drives the support device to move inward, retracting the entire winglet assembly.

[0089] The closure process is designed with aerodynamic loads in mind. The winglet needs to overcome aerodynamic forces during closure, therefore the transmission system must provide sufficient torque. The gear ratio is optimized to generate sufficient closing force at the motor's rated torque. The closing speed is slower than the deployment speed, typically 200 revolutions per minute, to reduce impact loads. A limit switch confirms the position after closure.

[0090] In one embodiment, the closing action takes approximately 40 seconds, the retraction action takes approximately 30 seconds, and the entire retraction process takes approximately 70 seconds. During retraction, the motor current is monitored in real time, and if abnormal resistance is encountered, the system will immediately stop and sound an alarm. Once retracted into position, the electromagnetic locking mechanism activates, locking the support device in the stowed position to prevent accidental movement during flight.

[0091] like Figures 1-3As shown, this invention provides a retractable forked winglet structure and a retractable wing for an unmanned aerial vehicle (UAV). The winglet structure includes a wing surface device, a support device, and a transmission device. The wing surface device has two pivots at its root, which respectively engage with two joints on the support device to form hinges. The support device uses the inner sides of the front and rear wing spars as slide rails and has a screw hole in its center that engages with the transmission device. The transmission device rotates to move the support device between the front and rear spars along the axis of the transmission shaft. The wing surface device retracts and opens / closes via the support device and the transmission device, which are simultaneously responsible for both retraction and opening / closing. Because the transmission shaft has a stepped design at the wingtip, meaning its diameter suddenly increases, as... Figures 4-6 As shown, after the support device moves the winglet assembly a certain distance towards the wingtip, the large-diameter portion of the drive shaft tip begins to contact the gear at the wing root. The drive shaft continues to rotate, and the support device continues to move towards the wingtip. The rotation of the large-diameter portion of the drive shaft tip causes the winglet assembly to rotate around the hinge formed by the wing root shaft and the drive device joint, thus causing the winglet to begin its bifurcated movement. When the winglet bifurcates to 40 degrees, the drive shaft stops moving, and the upper and lower winglets at the wingtip reach their deployed positions and are fixed. The winglet assembly includes: an upper winglet structure and a lower winglet structure; as shown... Figures 7-9 and Figure 13 As shown, the support device has four protruding joints. The root pivot of the upper winglet structure is hinged to the two upper joints on the support device, and the root pivot of the lower winglet structure is hinged to the two lower joints on the support device. There is no direct connection between the upper and lower winglet structures. The support device includes: a slider for fixing the winglets (i.e., a support device using the wing's fore and aft spars as guide rails), an upper winglet support (i.e., the two upper joints on the support device), and a lower winglet support (i.e., the two lower joints on the support device). The upper winglet support is fixed to the side of the slider, located above the hole through which the drive shaft passes; the lower winglet support is fixed to the side of the slider, located below the hole through which the drive shaft passes. Figures 10-12 As shown, the transmission device includes: a lead screw motor, a segmented lead screw, and front and rear slide rails. The front and rear slide rails are the front and rear spars of the wing and are structural components of the wing. The lead screw motor is fixed inside the wing and mounted on a bracket between the front and rear spars. The lead screw motor (the bracket that fixes the lead screw motor) is located adjacent to the slider (fixed device) in the direction of the wing root within its range of motion. The segmented lead screw (i.e., the stepped lead screw, the large-diameter part of the drive shaft is also described as this component) passes through the lead screw motor and is driven to rotate by the lead screw motor. The lead screw motor is fixed relative to the front and rear slide rails.

[0092] This invention innovatively combines the existing telescopic wings and adjustable winglets, designing a telescopic and retractable winglet that increases the effective aspect ratio, reduces induced drag, and saves spanwise space when retracted. During flight, the spanwise space is unrestricted, and the winglet can be extended to further increase the aspect ratio and improve flight stability. Furthermore, existing technologies require a separate motor to drive the winglet for angle adjustment or opening / closing, resulting in significant weight. This invention uses a segmented lead screw, enabling a single motor to control both the extension and retraction of the winglet, simplifying the mechanism, reducing weight, and increasing overall reliability due to the fewer motors required. Its specific advantages are reflected in the following four points: Bifurcation Angle Control: By precisely designing the reduction ratio of the lead screw motor, the pitch of the segmented lead screw, and the gear parameters, the maximum bifurcation angle of the winglet is precisely controlled at 40°. This angle has been verified by aerodynamic simulation and can achieve an optimization effect of reducing induced drag by more than 30%. Stroke control accuracy: The dual positioning method of double limit switch and motor encoder is adopted to ensure that the extension and retraction stroke error of the slider is ≤0.5mm and the bifurcation angle error is ≤1°. Structural strength optimization: The welding joints between the upper and lower winglet supports and the slider are reinforced with ribs to improve connection strength and withstand flight overload of ±10G; Protective design: The surfaces of all moving parts (such as gears, lead screws, and slide rails) are treated with anti-corrosion and wear-resistant materials. Dustproof sealing gaskets are installed inside the wing cavity to prevent dust and moisture from entering, thereby improving the structure's environmental adaptability and service life.

[0093] The foregoing has provided a detailed description of a retractable bifurcated winglet structure and a retractable wing for a UAV, as provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0094] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0095] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0096] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0097] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A telescopic forked winglet structure for an unmanned aerial vehicle (UAV), characterized in that, The retractable forked wingtip structure of the UAV includes a wing surface device, a support device, and a transmission device; The wing assembly includes an upper winglet structure and a lower winglet structure. The support device can be slidably installed inside the wing along the front and rear wing spars. The transmission device includes a lead screw motor and a segmented lead screw, the segmented lead screw having an inner section with a smaller diameter and an outer section with a larger diameter; the roots of the upper wing structure and the lower wing structure are respectively hinged to the support device, and the roots of the upper wing structure and the lower wing structure are fixedly connected to gears that mesh with the outer section; The support device is provided with a threaded hole that mates with the inner section thread; the lead screw motor drives the segmented lead screw to rotate, causing the support device to move along the axis of the segmented lead screw to drive the wing device to extend and retract as a whole; after the support device moves to the point where the gear meshes with the outer section, the outer section rotates to drive the upper wing structure and the lower wing structure to deflect in opposite directions around their respective hinge axes to achieve bifurcation.

2. The UAV telescopic forked winglet structure according to claim 1, characterized in that, The support device includes a slider, an upper connector, and a lower connector. The upper connector and the lower connector are fixed to the side of the slider and are located above and below the screw hole, respectively. The root of the upper winglet structure is hinged to the upper connector via a pivot, and the root of the lower winglet structure is hinged to the lower connector via a pivot. The slider is guided by the front and rear wing spars of the wing. The middle of the slider is provided with the through screw hole, which is continuously threaded into the inner section. The upper winglet structure and the lower winglet structure are initially housed parallel to each other inside the wing.

3. The UAV telescopic forked winglet structure according to claim 1, characterized in that, The segmented lead screw includes: an inner section that is threadedly engaged with a screw hole of the support device to enable the support device to translate axially; an outer section located at the end of the segmented lead screw near the wingtip and having a diameter larger than that of the inner section; the surface of the outer section is provided with a transmission structure that meshes with the gear; during the movement of the support device toward the wingtip, the inner section remains engaged with the screw hole while the gear does not contact the inner section.

4. The UAV telescopic forked winglet structure according to claim 1, characterized in that, The root gears of the upper and lower wing structures include: the gears are fixed to their respective roots and arranged around a hinge axis; the gears only mesh with the outer section after the support device moves to a predetermined position; when the outer section rotates, it drives the upper wing structure to deflect upward by meshing with the gears; when the outer section rotates, it drives the lower wing structure to deflect downward by meshing with the gears; the upper and lower wing structures deflect in opposite directions to form a bifurcated state.

5. The UAV telescopic forked winglet structure according to claim 1, characterized in that, The lead screw motor is fixedly installed inside the wing and is fixed relative to the front and rear wing spars. The segmented lead screw passes through the lead screw motor and is driven by the lead screw motor to rotate continuously. The lead screw motor is located on the side of the support device's range of motion close to the wing root. The unidirectional rotation of the lead screw motor sequentially realizes the extension of the wing surface device and the bifurcation and unfolding of the upper winglet structure and the lower winglet structure.

6. The UAV telescopic forked winglet structure according to claim 2, characterized in that, The upper joint includes two spaced-apart protruding structures to cooperate with the root pivot of the upper winglet structure to form a hinge; the lower joint includes two spaced-apart protruding structures to cooperate with the root pivot of the lower winglet structure to form a hinge; there is no direct connection between the upper winglet structure and the lower winglet structure; the support device slides stably along the front and rear wing spars of the wing via the slider.

7. The UAV telescopic forked winglet structure according to claim 3, characterized in that, The outer section and the inner section are coaxially connected to form a stepped diameter transition. The transmission structure of the outer section includes a worm or rack section to mesh with the gear. The segmented lead screw completes the axial displacement of the support device through the inner section in a single rotation direction. The segmented lead screw continues to rotate, causing the outer section to enter the meshing area with the gear to achieve bifurcated drive.

8. The UAV telescopic forked winglet structure according to claim 1, characterized in that, The retractable forked winglet structure of the UAV is integrated into the retractable wing. In the retracted state, the wing surface device is completely housed inside the wing. In the extended forked state, the retractable wing increases the effective aspect ratio of the wing through the upper winglet structure and the lower winglet structure. The screw motor rotates in the opposite direction to realize that the upper winglet structure and the lower winglet structure first close and then retract as a whole.

9. The UAV telescopic forked winglet structure according to claim 1, characterized in that, The lead screw motor is a DC brushless motor equipped with a reduction gear, and its output torque is not less than 5 N·m.

10. A retractable wing for an unmanned aerial vehicle (UAV), characterized in that, The UAV retractable wing includes a wing body and a UAV retractable forked winglet structure as described in any one of claims 1-9, wherein the retractable forked winglet structure can retract into the wing body or extend along the span of the wing body.

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