CN114313215B - A wing tip structure with variable inclination and height - Google Patents

Abstract

The invention discloses a wing tip structure with variable inclination angle and height, which includes a left wing rib, a driving mechanism, a deformation mechanism, a flexible skin, a right wing rib and a support structure; the left wing rib is clamped at 0°-90° The corner is installed on the main wing, the left wing rib is connected to the driving mechanism, the driving mechanism is connected to the deformation mechanism, and the deformation mechanism is connected to the right wing rib; the driving mechanism is used to drive the deformation mechanism to deform, changing the right wing rib relative to the left wing The spatial position of the rib; the two sides of the left wing rib and the right wing rib are connected through a support structure; the support structure is covered and installed with a flexible skin to form a closed aerodynamic shape. The deformation mechanism of the present invention adopts a planar linkage mechanism, which realizes the continuous elongation, shortening and bending of the wing tip structure, effectively improves the aerodynamic performance and maneuverability of the aircraft, increases the lift coefficient of the wing tip, reduces induced drag, and adapts to different flight environments. Requirements for aerodynamic shape.

Description

A wing tip structure with variable inclination and height

Technical field

The invention relates to the field of aerospace aircraft, specifically a wing tip structure with variable inclination angle and height.

Background technique

Ever since the Wright brothers invented the first airplane and humans realized their dream of flying, airplanes have played an important role in human society. However, in the early design process of aircraft, the wingtips were often fixed, and their aerodynamic characteristics were often optimized for a single purpose or a compromised design based on multiple flight environments. They could not change the posture of their wings at any time like a bird. Adjust flight status to achieve optimal flight performance. However, with the continuous improvement of various requirements for aircraft flight efficiency, aerodynamic performance, maneuverability and multi-mission, especially the development of drone technology, the disadvantages of traditional fixed-wing aircraft have gradually become prominent.

Relevant aerodynamic research shows that the airfoil can effectively improve the aerodynamic characteristics of the aircraft according to changes in different flight environments. Curved wing tips can improve maneuverability, reduce induced drag, and improve stall performance. K.K.Ishimitus of Boeing Company of the United States installed fixed winglets on an aerial tanker for the first time. Experimental results show that its drag is reduced by 7.2%, the lift-to-drag ratio is increased by 8%, and fuel consumption is reduced by 9%. At present, wingtips have been widely used, but the wingtip geometry is only designed for cruising, and the drag reduction efficiency during takeoff and climb stages is low. Research by Zuo Linxuan and others found that the unilateral deformation of the variable-tilt wingtip structure can significantly increase the yaw moment and pitching moment and improve the maneuverability of the aircraft. Li Wei from Nanjing University of Aeronautics and Astronautics studied the variable-height wing tip structure, and the results showed that it can significantly improve the strength of the wing tip wake vortex and increase the wing lift coefficient. The continuously variable wing tip structure during flight has broad application prospects.

In terms of changing the wing tip inclination angle, P. Bourdin et al. used the design of a servo motor-driven linkage mechanism to change the wing tip inclination angle. In addition, Boeing has also proposed a shape memory alloy-driven torsion tube structure to change the wing tip angle. Chinese patent application CN201920779634.X discloses a new type of wing tip variable inclination structure that uses piezoelectric fiber actuators to bend multi-terminal wings. Li Qiang and others from AVIC used an eccentric crank slider mechanism to drive the wing tips to rotate and change the inclination angle through connecting rod transmission. In terms of changing the wing tip height, Li Wen and others designed a telescopic structure driven by a steel cable winch to retract a section of the wing into the main wing in advance, and achieve continuous changes in the telescopic wing through the winch. Li Wei from Nanjing University of Aeronautics and Astronautics designed a differential telescopic grid mechanism. Two sets of telescopic grids are connected in parallel. By controlling the movement of the two sets of telescopic grids respectively, changes in the wing tip inclination angle and height are achieved, but it requires two sets of telescopic grids. motor drive. At present, most deformable wingtips are only designed for a single deformation mode. There are few designs that can perform two deformation modes at the same time, and they face weight issues.

The skin is mainly responsible for continuous deformation, maintaining aerodynamic shape and maintaining air tightness in morphing aircraft. Traditional skin materials are made of metal or composite materials, which have almost no deformation ability. With the in-depth exploration of morphing aircraft, a large number of flexible skins began to be designed and studied. There are mainly corrugated structure skins, honeycomb structure skins, fish scale structure skins, rubber skins and composite structure skins based on smart materials such as memory alloys. At present, most flexible skins can only achieve single-curvature stretching and bending deformation, or small-range double-curvature deformation such as torsion deformation. For example, honeycomb structures can only elongate or bend in-plane or twist in a small range. When bending occurs in the spanwise direction of the wing tip or at the wing tip, since the skin itself has already bent in the chord length direction, the skin needs to be able to achieve double curvature bending, that is, bending in the direction perpendicular to the chord length at the same time. At the same time, it is also necessary to prevent skin wrinkles, maintain smoothness, and have a certain load-bearing capacity. There are fewer designs for this type of skin structure.

In summary, the continuously variable wingtip structure during flight has broad application prospects. Most of the current deforming wingtips are only designed for one deformation mode. There are few designs that can perform two deformation modes at the same time. They also face problems such as heavy weight, difficult control, and complex structure. At the same time, it is also a big challenge to design a skin structure that can achieve double curvature, continuous smooth bending and a certain load-bearing capacity.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide a deformable wingtip structure with variable inclination angle and height, while maintaining a smooth and continuous appearance, and effectively improving the maneuverability, flight efficiency and multi-mission adaptability of the aircraft.

The purpose of the present invention is achieved through the following technical solutions:

A wing tip structure with variable inclination angle and height, including a left wing rib, a driving mechanism, a deformation mechanism, a flexible skin, a right wing rib and a support structure; the left wing rib is at an angle of 0°-90° Installed on the main wing, the left wing rib is connected to the driving mechanism, the driving mechanism is connected to the deformation mechanism, and the deformation mechanism is connected to the right wing rib; the driving mechanism is used to drive the deformation mechanism to deform, changing the right wing rib relative to the left side The spatial position of the wing rib; the left wing rib and the right wing rib are connected by a support structure on both sides; the support structure is covered and installed with a flexible skin to form a closed aerodynamic shape;

The driving mechanism includes a motor, a driving gear, an upper gear, an upper camshaft, a lower gear and a lower camshaft; the motor is installed on the main wing, and the output shaft of the motor passes through the left wing rib and is connected to the driving gear; The driving gear meshes with the upper gear and the lower gear to form a fixed-axis gear train; the upper camshaft is connected to the upper gear through a key, and the lower camshaft is connected to the lower gear through a key; the upper camshaft and the lower camshaft are connected to the deformation mechanism;

The deformation mechanism includes an upper push rod, a lower push rod, an upper connecting rod, a lower connecting rod and a slider. The deformation mechanism has two degrees of freedom; one end of the upper push rod is connected to the upper camshaft, and the other end is hinged to the upper connecting rod. middle part; one end of the lower push rod is connected to the lower camshaft, and the other end is hinged to the middle part of the lower connecting rod; the upper push rod and the lower push rod are parallel to each other; the end of the lower connecting rod is hinged to the slider, and the slider is connected to the end of the upper connecting rod; The top of the rod is hinged above the right wing rib, and the top of the lower link is hinged below the right wing rib;

Further, the motor drives the upper gear and the lower gear to rotate, thereby driving the upper camshaft and the lower camshaft to rotate. The upper camshaft and the lower camshaft are provided with spiral grooves to push the upper push rod and the lower push rod in a spiral transmission manner. The rod moves linearly, thereby changing the mutual position of the upper connecting rod and the lower connecting rod, and then continuously changing the spatial position and attitude of the right wing rib to achieve the purpose of deformation.

Furthermore, the spiral groove is designed through the inversion method; when the spatial position change of the right wing rib relative to the left wing rib is known, the upper and lower push rods are calculated through experiments or mechanism kinematic analysis. Run the trajectory to reverse engineer the cylindrical cam spiral groove.

Furthermore, when the spiral grooves of the upper camshaft and the lower camshaft are the same, the wingtips can extend and shorten; when the spiral grooves of the upper camshaft and the lower camshaft are opposite, the wingtips can bend upward. Or bent downward; several deformations can be achieved according to different spiral groove combinations.

Further, the flexible skin is composed of a spiral skeleton structure and an elastic matrix; the spiral skeleton structure is buried inside the elastic matrix; the spiral skeleton structure can achieve elongation, shortening, bending and torsional deformation in the axial direction, and can achieve longitudinal deformation. It has load-bearing capacity; the spiral skeleton structure has deformation constraints and matrix strengthening effects on the elastic matrix, preventing the elastic matrix from wrinkles during the deformation process.

Furthermore, the elastic matrix is made of rubber or shape memory polymer material; when rubber is used, a material that is difficult to drive automatically, the flexible skin can be passively deformed according to the wing tips; when shape memory polymer is used, the flexible skin can be externally It actively deforms under the influence of physical fields to meet the aerodynamic shape requirements of the wing under different flight missions.

Furthermore, the support structure is a double corrugated structure based on origami. The basic unit of the support structure is composed of two origami units folded according to the mirrored valley line distribution and spliced up and down; the basic unit is expanded in the three-dimensional direction and conforms to the shape of the wing rib. Cut; the basic unit can bear aerodynamic loads in the longitudinal direction, and can continuously bend and stretch deformation in the axial direction.

Compared with the existing technology, the beneficial effects brought by the technical solution of the present invention are:

1. The deformation mechanism in the present invention adopts a planar linkage mechanism, which realizes the continuous elongation, shortening and bending of the wing tip structure, effectively improves the aerodynamic performance and maneuverability of the aircraft, increases the lift coefficient of the wing tip, reduces induced drag, and adapts to different conditions. The requirements of the flight environment on aerodynamic shape.

2. In the present invention, a driving mechanism of a cylindrical cam is used to drive the deformation mechanism. The cylindrical cam can be reversely designed according to the deformation mode of the wing tip, which expands the deformation mode of the wing tip and improves the multi-tasking and maneuverability of the aircraft. And through the deformation mechanism driven by a single motor, the weight of the wing tip is reduced, the structure is simple, the stiffness is good, and the reliability is high.

3. The flexible skin designed in the present invention embeds the spiral skeleton structure into the elastic matrix, realizing the elongation, shortening, bending and torsional deformation of the flexible skin, and can adapt to the diverse deformation modes of the wing tips. It has smooth deformation, good flexibility, simple structure, lightweight and certain load-bearing capacity, and has broad application prospects in the field of morphing aircraft.

4. The support structure designed in the present invention is a double-corrugated structure based on origami, which is characterized by being very stiff in the longitudinal direction to bear aerodynamic loads, but flexible in the axial direction, capable of bending and elongation deformation, and at the same time being lightweight. Features.

5. In the present invention, the spiral grooves on the camshaft can be designed by the inversion method; in addition, when the spiral grooves of the upper camshaft and the lower camshaft are the same, the wing tips can be extended and shortened. When the spiral grooves of the upper and lower camshafts are opposite, the wingtips can bend upward or downward. At the same time, different combinations of spiral grooves can achieve more complex deformations.

6. The flexible skin in the present invention is a skeleton-reinforced elastomer. The spiral skeleton structure can achieve elongation and bending deformation in the axial direction, has strong deformation ability and various deformation modes, and has load-bearing capacity in the longitudinal direction. The spiral skeleton structure has deformation constraints and matrix strengthening effects on the wrapped elastic matrix, preventing the elastic matrix from wrinkles during the deformation process. The spiral skeleton structure can be made of metal or non-metal materials such as manganese steel and 7075 aluminum alloy with good elasticity and high yield strength.

7. The support structure is a double corrugated structure based on origami. Its basic unit is composed of two origami units folded according to a specific valley line distribution and spliced up and down. The basic unit is expanded in three dimensions and cut according to the shape of the rib. It is very rigid in the longitudinal direction to bear aerodynamic loads, but flexible in the axial direction and can achieve deformations such as bending and stretching. Its main purpose is to make up for the problem of insufficient bearing capacity of flexible skins under high aerodynamic loads without hindering deformation.

Description of the drawings

Figure 1 is a side view of the wing tip structure of the present invention.

Figure 2 is a schematic diagram of the shape of the wing tip before deformation in the present invention.

Figure 3 is a schematic diagram of the shape of the wing tip changing height in the present invention.

Figure 4 is a schematic diagram of the shape of the wing tip bent upward according to the present invention.

Figure 5 is a schematic diagram of the shape of the wing tip bent downward according to the present invention.

Figure 6 is a schematic structural diagram of the deformation mechanism in the present invention.

Figure 7 is a side view of the driving mechanism of the present invention.

Figure 8 is a schematic structural diagram of the fixed-axis gear train in the present invention.

Figure 9 is a side view of the upper push rod in the present invention.

Figure 10 is a right side view of the upper push rod in the present invention.

Figure 11 is a cross-sectional view of the flexible skin structure of the present invention.

Figure 12 is a schematic diagram of the flexible skin spiral skeleton structure before deformation and a schematic cross-sectional structural diagram along the A-A direction in the present invention.

Figure 13 is a schematic diagram of the elongated configuration of the flexible skin spiral skeleton structure and a schematic cross-sectional structural diagram of the B-B direction in the present invention.

Figure 14 is a schematic diagram of the bending configuration of the flexible skin spiral skeleton structure and a schematic cross-sectional structural diagram of the C-C direction in the present invention.

Figure 15 is the basic structural unit of the double corrugated structure based on origami in the present invention.

Figure 16 is a side view of the expanded configuration of the basic unit of the double corrugated structure based on origami in the present invention.

Figure 17 is a schematic diagram of the filling configuration of the double corrugated structure based on origami in the present invention.

Figure 18 is a schematic bending diagram and a schematic diagram of the E-E cross-sectional structure of the double corrugated structure based on origami in the present invention.

Reference signs: 1-left wing rib, 2-driving mechanism, 3-deformation mechanism, 4-flexible skin, 5-support structure, 21-motor, 22-driving gear, 23-upper gear, 24-upper cam Shaft, 25-lower gear, 26-lower camshaft, 31-upper push rod, 32-upper connecting rod, 33-lower push rod, 34-lower connecting rod, 35-slider, 36-right wing rib, 41 -Helix skeleton structure, 42-elastic matrix, 51-origami unit, 52-origami unit.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

As shown in Figures 1 to 10, a wing tip structure with variable inclination angle and height includes a left wing rib 1, a driving mechanism 2, a deformation mechanism 3, a flexible skin 4 and a support structure 5. The left wing rib 1 is installed on the main wing at a certain angle, and the driving mechanism 2 is fixed on the left wing rib 1 to drive the deformation mechanism 3 to deform and change the spatial position of the right wing rib relative to the left wing rib 1. The flexible skin 4 covers the entire outside of the wing tip to maintain a smooth, supple and closed aerodynamic shape. The support structure 5 is placed under the flexible skin to enhance the load-bearing capacity of the flexible skin 1 while maintaining its deformation capability.

As shown in FIG. 3 , the driving mechanism includes a motor 21 , a driving gear 22 , an upper gear 23 , an upper camshaft 24 , a lower gear 25 and a lower camshaft 26 . The driving gear 22 is fixed to the motor output shaft. The motor 21 is installed on the main wing, and the output shaft of the motor 21 passes through the left wing rib 1 and is connected to the driving gear 22; the motor 21, the upper gear 23 and the lower gear 25 are fixed to the left wing rib 1. The driving gear 22, the upper gear 23 and the lower gear 25 form a fixed-axis gear train. The upper camshaft 24 is keyed to the upper gear 23, and the lower camshaft 26 is keyed to the lower gear 25. The upper camshaft 24 and the lower camshaft 26 are connected to the deformation mechanism.

As shown in Figure 3, the deformation mechanism includes an upper push rod 31, a lower push rod 33, an upper link 32, a lower link 34, a slider 35 and a right wing rib 36, and its degree of freedom is 2. One end of the upper push rod 31 is connected to the upper camshaft 24, and the other end is hinged to the middle part of the upper connecting rod 32. One end of the lower push rod 33 is connected to the lower camshaft 26, and the other end is hinged to the middle part of the lower connecting rod 34. The upper push rod 31 and the lower push rod 33 are parallel to each other. The end of the lower link 34 is hinged to the slider 35 , and the slider 35 is connected to the upper link 32 . The top end of the upper link 32 is hinged above the right wing rib 36 , and the top end of the lower link 34 is hinged below the right wing rib 36 .

In the present invention, the motor 21 drives the upper gear 23 and the lower gear 25 to rotate, thereby driving the upper camshaft 24 and the lower camshaft 26 to rotate. The upper camshaft 24 and the lower camshaft 26 are designed with spiral grooves, which are driven by the spiral. The upper push rod 31 and the lower push rod 33 are pushed to make linear motion, thereby changing the mutual positions of the upper link 32 and the lower link 34. The tops of the upper link 32 and the lower link 34 are hinged to the right wing rib 36, thereby changing The spatial position and attitude of the right wing rib 36 are to achieve the purpose of deformation.

Furthermore, the spiral grooves on the upper camshaft 24 and the lower camshaft 26 can be designed by the inversion method. When the spatial position change of the right wing rib 36 relative to the left wing rib 1 is known, the running trajectories of the upper push rod 31 and the lower push rod 33 can be calculated through experiments or mechanism theory, thereby reversely designing the upper camshaft 24 and the lower push rod 33 . The spiral groove on the lower camshaft 26.

Furthermore, when the spiral grooves of the upper camshaft 24 and the lower camshaft 26 are the same, the wingtips can be elongated in the lengthwise direction, as shown in FIG. 3 . When the spiral grooves of the upper camshaft 24 and the lower camshaft 26 are opposite, the wing tips can bend upward or downward, as shown in Figures 4-5. At the same time, different combinations of spiral grooves can achieve more complex deformations.

As shown in Figures 11-14, the flexible skin 4 in this embodiment is a skeleton-reinforced elastomer. The spiral skeleton 41 structure can achieve elongation and bending deformation in the axial direction, has strong deformation ability and various deformation modes, and has a certain load-bearing capacity in the longitudinal direction. The structure of the spiral skeleton 41 exerts deformation constraints and matrix strengthening effects on the wrapped elastic matrix 42, preventing it from wrinkles during the deformation process. The spiral skeleton 41 structure can be made of metal or non-metal materials such as manganese steel and 7075 aluminum alloy with good elasticity and high yield strength.

Furthermore, the elastic base 42 can be made of rubber material with high elastic limit and low Young's modulus, which can produce large deformation under small driving force. The composed flexible skin 4 passively deforms according to the wing tips to achieve aerodynamic shape requirements under different flight missions.

Further, the support structure 5 is a double corrugated structure based on origami. As shown in Figure 15, its basic unit is composed of origami units 51 and 52 folded according to a specific valley line distribution and spliced up and down, where the solid line represents the mountain line and the dotted line represents the valley line. The basic unit is expanded in the three-dimensional direction, and its expanded configuration is shown in Figure 16. The extended structure is cut according to the shape of the wing rib and fills the inside of the wing tip as filler. It can be formed by 3D printing or surface-to-surface bonding. It is characterized by being very rigid in the longitudinal direction to bear aerodynamic loads, but flexible in the axial direction and capable of achieving bending and other deformations. The initial filling configuration is shown in Figure 17, and the bending configuration is shown in Figure 18.

The invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are only illustrative and not restrictive. Without departing from the spirit of the present invention and the scope protected by the claims, those of ordinary skill in the art can make many specific changes based on the inspiration of the present invention, and these all fall within the protection scope of the present invention.

Claims (6)

1. The wing tip structure with the variable dip angle and the variable height is characterized by comprising a left wing rib, a driving mechanism, a deformation mechanism, a flexible skin, a right wing rib and a supporting structure; the left wing rib is arranged on the main wing at an included angle of 0-90 degrees, the left wing rib is connected with the driving mechanism, the driving mechanism is connected with the deformation mechanism, and the deformation mechanism is connected with the right wing rib; the driving mechanism is used for driving the deformation mechanism to deform and changing the spatial position of the right flank rib relative to the left flank rib; the two sides of the left wing rib and the right wing rib are connected through a supporting structure; the support structure is covered and provided with a flexible skin to form a closed pneumatic shape;

the driving mechanism comprises a motor, a driving gear, an upper cam shaft, a lower gear and a lower cam shaft; the motor is arranged on the main wing, and an output shaft of the motor penetrates through the left flank rib to be connected with the driving gear; the driving gear is meshed with the upper gear and the lower gear to form a fixed-axis gear train; the upper cam shaft is connected with the upper gear through a key, and the lower cam shaft is connected with the lower gear through a key; the upper cam shaft and the lower cam shaft are connected with the deformation mechanism;

the deformation mechanism comprises an upper push rod, a lower push rod, an upper connecting rod, a lower connecting rod and a sliding block, and has 2 degrees of freedom; one end of the upper push rod is connected with the upper cam shaft, and the other end of the upper push rod is hinged to the middle part of the upper connecting rod; one end of the lower push rod is connected with the lower cam shaft, and the other end of the lower push rod is hinged to the middle part of the lower connecting rod; the upper push rod and the lower push rod are parallel to each other; the tail end of the lower connecting rod is hinged with a sliding block, and the sliding block is connected with the tail end of the upper connecting rod; the top end of the upper connecting rod is hinged above the right wing rib, and the top end of the lower connecting rod is hinged below the right flank rib; the motor drives the upper gear and the lower gear to rotate, thereby driving the upper cam shaft and the lower cam shaft to rotate, the upper cam shaft and the lower cam shaft are provided with spiral grooves, the upper push rod and the lower push rod are pushed to do linear motion in a spiral transmission mode, the mutual positions of the upper connecting rod and the lower connecting rod are changed, and the spatial position and the gesture of the right flank rib are continuously changed to achieve the purpose of deformation.

2. A variable pitch and height wing tip structure according to claim 1, wherein the spiral groove is designed by inversion; when the spatial position of the right flank rib relative to the left flank rib is known to change, the running track of the upper push rod and the lower push rod is calculated through experiments or mechanical kinematics analysis, so that the cylindrical cam spiral groove is reversely designed.

3. A variable pitch and height wing tip structure according to claim 1, wherein the wing tip is capable of achieving extension and contraction when the helical grooves of the upper and lower camshafts are identical; when the spiral grooves of the upper cam shaft and the lower cam shaft are opposite, the wing tip can realize upward bending or downward bending of the wing tip; according to different spiral groove combinations, a plurality of deformations are realized.

4. A variable pitch and height wing tip structure according to claim 1, wherein the flexible skin is comprised of a helical skeleton structure and an elastomeric matrix; the spiral skeleton structure is buried in the elastic matrix; the spiral skeleton structure can realize elongation, shortening, bending and torsional deformation in the axial direction and has bearing capacity in the longitudinal direction; the spiral skeleton structure has deformation constraint and matrix strengthening effects on the elastic matrix, and the elastic matrix is prevented from being wrinkled in the deformation process.

5. A variable pitch and height wing tip structure according to claim 4, wherein the elastomeric matrix is rubber or a shape memory polymer material; when a material which is hard to actively drive, such as rubber, is selected, the flexible skin can be passively deformed according to the wing tip; when the shape memory polymer is selected, the flexible skin can actively deform under the action of an external physical field so as to meet the requirements of the wing on aerodynamic shape under different flight tasks.

6. The wing tip structure with variable inclination angle and height according to claim 1, wherein the supporting structure is a double corrugated structure based on paper folding, and the supporting structure basic unit is formed by folding two paper folding units according to mirror image valley line distribution and splicing the two paper folding units up and down; the basic units are expanded in the three-dimensional direction and cut according to the shape of the wing ribs; the basic unit can bear aerodynamic load in the longitudinal direction and can continuously bend and stretch in the axial direction.