Flexible thrust vectoring nozzle based on porous polyvinyl chloride gel driver

Abstract

The invention discloses a flexible thrust vectoring nozzle based on a porous polyvinyl chloride gel driver, and belongs to the technical field of intelligent material application. The invention provides a preparation process of a porous PVC gel driver and designs a flexible thrust vectoring nozzle structure. The flexible thrust vectoring nozzle structure is composed of a porous PVC gel flexible driver, a nozzle fixed body, a nozzle movable body, a cross shaft mechanism, a connecting hinge and a height adjusting mechanism. The casting mold is designed through abrasive paper, the PVC gel with the rough surface and the bubble structure inside is prepared, the structural rigidity of the PVC gel is reduced, the output displacement of the gel under the same electric field intensity is increased, and the driving performance of a PVC gel driver is improved. According to the flexible thrust vectoring nozzle, the driver is arranged at the throat part of the nozzle and is matched with the cross shaft mechanism and the connecting hinge, so that the PVC gel flexible driver simultaneously realizes three functions of connecting, bearing and driving, and a new vector control scheme is provided for the thrust vectoring nozzle.

Description

Technical Field

[0001] This invention patent belongs to the technical field of intelligent material applications, and particularly relates to the application of an electroactive polymer material, PVCgel.

[0002] Thrust vectoring technology refers to the technology that the thrust component generated by the deflection of the engine thrust through the nozzle or the exhaust jet flow is used to control the flight attitude of the aircraft in real time. During flight, thrust vectoring technology can achieve three actions of the aircraft: pitch, yaw, and roll. To improve the vector control accuracy of space vehicles, researchers have proposed different types of nozzle structures and drive strategies. According to the working principle, the implementation schemes of traditional thrust vector nozzles can be divided into fluid injection types, gas rudders, baffle plates, jet deflection rings, and movable nozzles, etc. However, fluid injection types require complex jet channels and flow control systems, and have high requirements for processing quality and control accuracy. (Tian Hui, Tan Guang, Ge Xuanhong, etc. Solid-liquid rocket engine thrust vector nozzle [P]. Beijing: CN202311768384.7, 2024-02-27.) (Geng Lingbo, Wang Chao, Hu Zhiqiang, etc. A thrust vector nozzle using flow control [P]. Liaoning: CN202110274442.5, 2022-09-20.) The drive devices of gas rudders, baffle plates, jet deflection rings, and various movable nozzles are generally hydraulic actuators, with complex structures and excessive weights, which are not conducive to the miniaturization and lightweight of the aircraft. (Huang Shuai, Lan Jiazhe, Xu Jinglei, etc. An aerodynamic thrust vector nozzle and its control method [P]. Jiangsu: CN202311169020.7, 2023-11-10.) (Sun Huawang, Ma Chengcheng, Li Xingyong, etc. A small-size dual-channel vector nozzle hydraulic servo mechanism [P]. Shanghai: CN202311431646.0, 2024-01-30.) (Qu Shiyi, Zhang Xiaobo, Wang Zhanxue, etc. A micro-axisymmetric vector nozzle suitable for small aircraft [P]. Shaanxi: CN202310720156.6, 2023-09-01.)

[0003] Therefore, getting rid of the traditional driving method and reducing the mass and structural complexity of the vector control system are important research directions for improving the miniaturization and lightweight of the thrust vector nozzle. As a new type of electroactive polymer material, polyvinyl chloride gel (PVCgel) has the advantages of moderate driving voltage, convenient driving, easy manufacturing, and easy miniaturization. Further, the existing shrinkage displacement of PVC gel still needs to be improved, and its structure is single, which greatly limits its practical application. Therefore, it is a relatively feasible optimization scheme to improve its shrinkage displacement by changing the structural characteristics of PVC gel. (Yi Li, Minoru Hashimoto. PVC gel based artificial muscles: Characterizations and actuation modular constructions[J]. Sensors&Actuators:A.Physical, 2015, 233.). Therefore, by optimizing the preparation process, improving the shrinkage displacement of PVC gel, and applying the PVC gel actuator to the thrust vector nozzle is one of the ideal solutions to promote the miniaturization and lightweight of the thrust vector nozzle. Summary of the Invention

[0004] To solve the technical problems of traditional vector nozzles in miniaturization and lightweight, according to the electroactuation characteristics of PVC gel, the present invention develops a preparation process of porous PVC gel, designs a porous PVC gel actuator, and further designs a flexible vector nozzle based on the porous polyvinyl chloride gel actuator.

[0005] A preparation method of porous PVC gel includes the following steps:

[0006] 1) Weigh three chemical reagents of polyvinyl chloride, plasticizer, and tetrahydrofuran according to a certain mass ratio;

[0007] 2) Mix and stir, mix the above three reagents in the same conical flask and stir well;

[0008] 3) Pour the evenly stirred transparent solution onto a special petri dish, the special petri dish includes a stainless steel petri dish and waterproof sandpaper, fix the sandpaper at the bottom of the petri dish, and make the transparent solution contact the rough surface of the sandpaper when the gel is poured;

[0009] 4) Place the above petri dish in a fume hood and let it volatilize naturally until the tetrahydrofuran is completely volatilized to obtain a porous PVC gel with a rough structure on the surface and a part of air bubbles preserved inside the gel, and lower structural stiffness.

[0010] The present invention also discloses a porous PVC gel flexible actuator, which includes porous PVC gel prepared by the above-mentioned PVC gel preparation method, and also includes a driving unit cathode and a driving unit anode. The porous PVC gel flexible actuator is combined in the arrangement order of "anode - porous PVC gel - cathode - porous PVC gel - anode... anode".

[0011] Preferably, the cathode is a copper foil and the anode is a wire mesh.

[0012] Preferably, when the power supply is energized, a part of the volume of the PVC gel is embedded into the gaps of the wire mesh grid, and the distance between the copper foil and the wire mesh is shortened; when the power supply is disconnected, the PVC gel returns to its original position, and the distance between the copper foil and the wire mesh is restored; the changes in the distance between the electrodes are accumulated on the porous PVC gel flexible actuator, and the overall manifestation is the contraction and restoration in the thickness direction of the actuator.

[0013] The present invention also discloses a flexible vector nozzle based on a porous polyvinyl chloride gel actuator, which includes a nozzle moving body, a porous PVC gel flexible actuator, and a nozzle fixed body; the lower end of the porous PVC gel flexible actuator is embedded in the actuator fixing groove of the nozzle fixed body, and the upper end is connected to the nozzle moving body through a connecting member, converting the linear displacement of the actuator into the swing of the moving body.

[0014] Preferably, the connecting member is a connecting hinge, which includes upper and lower parts. The upper part includes a hinge ball head, a hinge ball rod, and a hinge upper base connected in sequence. The lower part includes a hinge lower base, and the inner wall of the spherical groove is embedded in the hinge lower base. The hinge ball head cooperates with the inner wall of the spherical groove and has three degrees of freedom of rotation. Through relative rotation, the displacement output by the actuator can be converted into the swing of the moving body.

[0015] Preferably, the upper end of the porous PVC gel flexible actuator is fixedly connected to the hinge lower base of the connecting hinge, and a hinge base is provided on the nozzle moving body. The connecting hinge is fixed on the connecting hinge base of the nozzle moving body through the hinge upper base.

[0016] Preferably, the flexible vector nozzle further includes a height adjustment mechanism, which includes an adjustable knob and an adjustment backing plate. The adjustment backing plate is arranged in the actuator fixing groove and is provided with an adjustment backing plate hole. Correspondingly, an adjustable knob threaded hole is opened on the actuator fixing groove, and the lower end of the porous PVC gel flexible actuator contacts the adjustment backing plate; when the adjustable knob rotates in the adjustable knob threaded hole, the adjustable knob makes an axial displacement relative to the nozzle moving body, thereby pushing the adjustment backing plate to move up and down. By pressing the adjustment backing plate of the height adjustment mechanism, the initial installation gap is adjusted by the adjustable knob.

[0017] Preferably, to ensure that the moving body always has a fixed swing center during the swinging process and prevent the moving body from rotating along its own axis, a cross-axis structure is provided at the nozzle throat. The cross-axis sub-axis provided on the moving body cooperates with the cross-axis female hole to ensure that the moving body can only rotate relative to the axis of the cross-axis female hole; the cross-axis female hole cooperates with the cross-axis hole on the nozzle fixed body to ensure that the cross-axis mother can only rotate relative to the axis of the cross-axis hole on the nozzle fixed body; during assembly, the cross-axis hole and the cross-axis female hole are coaxially matched, the cross-axis female hole and the cross-axis sub-axis are coaxially matched, and the cross-axis female holes are orthogonal to each other. Therefore, the nozzle moving body only retains the freedom of rotation along two horizontal axes relative to the nozzle fixed body, restricting the other four degrees of freedom.

[0018] Beneficial effects

[0019] The porous PVC gel proposed by the present invention has the advantages of large output displacement, light weight, and simple preparation process. The PVC gel actuator in this design is located between the moving body and the fixed body to achieve the connection function; when the gel is electrified, it shrinks and deforms, driving the moving body to deflect relative to the fixed body to achieve the driving function; during the period when vector control is not required, if the aircraft receives a small disturbance, the actuator can act as a buffer to achieve the bearing function, making the flexible vector nozzle structure based on the porous polyvinyl chloride gel actuator more compact, with more perfect functions, and more conducive to the lightweight and miniaturization of the aircraft. Brief description of the drawings

[0020] Figure 1 Isometric view of the flexible vector nozzle of an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the preparation process and gel structure of the porous PVC gel of an embodiment of the present invention;

[0022] Figure 3 Shrinkage displacement test results of each gel sample of an embodiment of the present invention under different driving voltages;

[0023] Figure 4 Schematic diagram of the flexible actuator structure based on PVC gel of an embodiment of the present invention;

[0024] Figure 5 Isometric view of the nozzle moving body of an embodiment of the present invention;

[0025] Figure 6 Isometric view of the nozzle fixed body of an embodiment of the present invention;

[0026] Figure 7 Exploded view of the height adjustment mechanism of an embodiment of the present invention;

[0027] Figure 8Exploded assembly view of the cross shaft mechanism according to an embodiment of the present invention;

[0028] Figure 9 Exploded view of the connecting hinge according to an embodiment of the present invention;

[0029] Figure 10 Schematic diagram of the cross shaft female according to an embodiment of the present invention.

[0030] Reference numerals in the figure: 1, nozzle movable body, 1-1, convergent section of the nozzle movable body, 1-2, divergent section of the nozzle movable body, 1-3, connecting hinge base, 1-4, cross shaft sub-axis, 1-5, spherical structure, 2, connecting hinge, 2-1, upper hinge base, 2-2, lower hinge base, 2-3, hinge ball head, 2-4, hinge ball rod, 2-5, inner wall of the spherical groove, 3, porous PVC gel flexible actuator, 4, nozzle fixed body, 4-1, ear, 4-2, threaded hole for adjustable knob, 4-3, trunnion connection hole, 4-4, cross shaft hole, 4-5, nozzle throat, 4-6, actuator fixing groove, 5, height adjustment mechanism, 5-1, adjustable knob, 5-2, adjustment pad, 5-3, adjustment pad hole, 6, cross shaft mechanism, 6-1 cross shaft female axis, 6-2, cross shaft female hole. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] Embodiment 1

[0033] In this embodiment, a preparation process of porous PVC gel is disclosed. The present invention utilizes the uneven surface of sandpaper and proposes a new process that can generate bubbles and retain the bubbles inside the gel. The operation is convenient and the process is simple. The specific principle of bubble generation is as follows: After polyvinyl chloride, plasticizer, and tetrahydrofuran are mixed evenly, some polar molecules between polyvinyl chloride and the plasticizer interact with each other, and the fluidity of the mixed solution is poor. Therefore, when this solution is cast on the surface of sandpaper, the large surface tension makes the solution unable to completely fill the gaps on the surface of the sandpaper. After a period of time, a part of tetrahydrofuran volatilizes from the upper surface of the solution in direct contact with air, and a semi-solid film is formed on the surface; at this time, due to the action of gravity, the gel solution slowly enters the gaps on the surface of the sandpaper, and the bubbles in the gaps float upward; the upper film is relatively dense and does not allow bubbles with a large volume to pass through. Therefore, the bubbles are retained inside the gel solution; after all the tetrahydrofuran in the solution volatilizes, the gel is distributed with uniformly sized bubbles in the order of hundreds of micrometers.

[0034] As Figure 2 shown, the preparation process of the porous PVC gel includes the following steps:

[0035] 1) Weigh the reagents and continuously stir. Weigh three chemical reagents of polyvinyl chloride, plasticizer, and tetrahydrofuran with a mass ratio of 1:9:15. After mixing the three, continuously stir for more than 48 hours (the rotation speed of the magnetic stirrer is above 1000 r / min, and it is required that the conical flask is well sealed) to form a homogeneous and transparent solution;

[0036] 2) Cast the solution. Pour the uniformly stirred transparent solution onto a petri dish with waterproof sandpaper laid on the bottom surface according to the thickness calculation formula. It is required that the bottom surface of the petri dish is flat and kept horizontal;

[0037] 3) Volatilize and form. Place the transparent solution cast on the special petri dish in a fume hood and let it naturally volatilize for more than 48 hours to ensure that the tetrahydrofuran is completely volatilized;

[0038] 4) Demold. Use tools such as tweezers to take out the solidified gel from the petri dish.

[0039] Compared with the ordinary casting method, on the one hand, laying sandpaper on the surface of the petri dish can make the PVC gel after demolding have a rough surface structure; on the other hand, the gel solidifies from top to bottom. Therefore, the air in the sandpaper pores leaves the sandpaper and enters the gel solution under the action of buoyancy, and the already solidified gel on the upper layer prevents it from overflowing inside the gel, thus preserving it inside the volume, which also achieves the effect of reducing the gel stiffness. In view of the electro - actuation principle of PVC gel, the smaller the gel stiffness, the easier it is to deform under the action of the electric field force, and thus a larger displacement can be output. All in all, this casting process reduces the stiffness of PVC gel and improves its electro - actuation performance.

[0040] The mechanism of the electro - actuation characteristics of PVC gel is as follows: Under the action of the electric field force, the plasticizer molecules inside the PVC gel deflect or migrate directionally. Macroscopically, it is manifested that the volume of the gel on the cathode side decreases, the volume of the gel on the anode side increases, and the distance between the two electrodes on both sides of the gel decreases. During this process, the dielectric properties and structural stiffness of the gel are the two most important factors affecting its performance, and the two restrict each other. Therefore, adjusting the content of air bubbles inside the gel is a feasible research plan to improve its driving performance.

[0041] As Figure 3 shown, in this experiment, by changing the fineness of the sandpaper in the casting mold, the content of air bubbles inside the gel was changed, and thus the shrinkage displacement performance of the gel was changed.

[0042] Example 2

[0043] In this embodiment, a porous PVC gel flexible actuator is disclosed, which includes porous PVC gel prepared by the PVC gel preparation method disclosed in Embodiment 1, and also includes a driving unit cathode and a driving unit anode. The above-mentioned porous PVC gel flexible actuator is assembled in the order of "anode - gel - cathode - gel - anode... anode", as Figure 4 shown.

[0044] According to the electroactuation characteristics of porous PVC gel, a steel wire mesh with a mesh density of 8 meshes is used as the anode of the driving unit, and a copper foil with a thickness of 0.01 mm is used as the driving unit cathode to form a driving unit in the order of "anode - gel - cathode". Among them, the contraction displacement of the PVC gel driving unit corresponding to 36 - mesh sandpaper is 0.3 mm under a driving voltage of 600 V. Compared with the contraction displacement (0.17 mm) of the "smooth plane" - type PVC gel driving unit prepared by a traditional flat culture dish, it has increased by 76%.

[0045] The porous PVC actuator of this embodiment is composed of 14 steel wire mesh anodes, 13 copper foil cathodes and 26 layers of porous PVC gel in sequence, with an overall thickness of 38 mm. When driven by a voltage of 800 V, the actuator can output a displacement of 4.8 mm. Assembled on the nozzle, it can drive the nozzle moving body to swing about 5.4° relative to the nozzle fixed body.

[0046] When the power supply is energized, according to the above - mentioned actuation mechanism, a part of the volume of the PVC gel is embedded into the gaps of the steel wire mesh grid, resulting in a shortening of the distance between the copper foil and the steel wire mesh; when the power supply is disconnected, the PVC gel returns to its original position, and the distance between the copper foil and the steel wire mesh is restored. The changes in the distance between the electrodes are accumulated on the porous PVC gel flexible actuator 3, and the overall manifestation is the contraction and recovery in the thickness direction of the actuator.

[0047] Embodiment 3

[0048] This embodiment discloses a flexible vector nozzle based on a porous polyvinyl chloride gel actuator, which includes a nozzle moving body 1, a connecting hinge 2, a porous PVC gel flexible actuator 3, a nozzle fixed body 4, a height - adjusting mechanism 5 and a cross - shaft mechanism 6.

[0049] The nozzle moving body 1 (as Figure 5As shown in the figure, it is generally in the shape of an inverted wine glass, including the converging section 1-1 of the nozzle movable body and the diverging section 1-2 of the nozzle movable body. A connecting hinge base 1-3 (for cooperating with the connecting hinge 2) and a spherical structure 1-5 are provided on the converging section 1-1 of the nozzle movable body, and a cross-axis sub-axis 1-4 is provided on the spherical structure 1-5. Among them, the shapes of the converging section 1-1 of the nozzle movable body and the diverging section 1-2 of the nozzle movable body are designed in accordance with the Laval nozzle principle, which can convert the kinetic energy of part of the combustion gas flow into the power of the aircraft; the cross-axis sub-axis 1-4 cooperates with the cross-axis mother and the cross-axis hole to fix the swing center of the movable body; the function of the spherical structure 1-5 is to reduce stress concentration.

[0050] As the support structure of the entire nozzle, the nozzle fixed body 4 (as shown in Figure 6 the figure) is fixed to the aircraft fuselage to provide a reaction force for the actuator. When the porous PVC gel actuator 3 is energized and contracts, the nozzle movable body 1 swings, and the nozzle fixed body 4 remains stationary to generate a change in the thrust vector. The nozzle fixed body 4 mainly includes a nozzle throat 4-5 and an actuator fixing groove 4-6. A cross-axis hole 4-4 is opened on the nozzle throat 4-5, which is coaxially matched with the mother axis 6-1 of the cross-axis mechanism 6 to limit the nozzle movable body 1 to only retain the controllable swing degrees of freedom around two orthogonal axes. An ear 4-1 is provided on the actuator fixing groove 4-6, and an ear shaft connection hole 4-3 is opened in the center of the ear 4-1, which is used to install the entire nozzle structure on the aircraft to provide a mechanical connection point; an adjustable knob threaded hole 4-2 is used to cooperate with the height adjustment mechanism 5 to realize the height adjustment of the porous PVC gel actuator 3.

[0051] The nozzle movable body 1 and the nozzle fixed body 4 are assembled based on the cross-axis mechanism 6 to ensure that there is always a fixed swing center during the swinging process and prevent the movable body from rotating along its own axis. The cross-axis mechanism 6 includes a cross-axis mother axis 6-1, a cross-axis mother hole 6-2 and a cross-axis mother. The specific structure of the cross-axis mother is as shown in Figure 10 the figure. As shown in Figure 8 the figure, it is the assembly method of the nozzle movable body 1 and the cross-axis mother. The cross-axis sub-axis 1-4 on the nozzle movable body is coaxially matched with the cross-axis mother hole 6-2, and then this sub-assembly is assembled on the nozzle fixed body 4, where the cross-axis sub-axis 1-4 is designed on the outside of the transition part between the converging section 1-1 and the diverging section 1-2 of the nozzle movable body, as shown in Figure 6As shown in the figure. The cross-axis sub-shafts 1-4 are coaxially fitted with the cross-axis holes 4-4 of the nozzle throat 4-5 in the nozzle fixing body 4, and then the nozzle moving body 1 is assembled onto the nozzle fixing body 4 to restrict the nozzle moving body 1, only retaining the controllable swinging degrees of freedom around two orthogonal axes, fixing the position of the swing center, and avoiding unexpected displacement. In this embodiment, for the convenience of assembling the spherical structure and the spherical groove, the cross-axis mother, the nozzle fixing body 4 and the hinge lower base 2-2 are designed into a centrosymmetric and split structure. For example, the nozzle fixing body 4 is divided into two centrosymmetric parts. After assembling the nozzle moving body 1 and the cross-axis mother hole 6-2, the two parts of the nozzle fixing body are assembled together using fixing bolts and fixing nuts.

[0052] The porous PVC gel flexible actuator 3 is located between the moving body and the fixing body to achieve the connection function. The assembly method of the porous PVC gel flexible actuator 3 is as Figure 1 shown. As Figure 4 shown, the composite sandwich structure is arranged around the outside of the nozzle moving body 1. The lower end of the actuator contacts the height adjustment mechanism 5, and the upper end cooperates with the connecting hinge 2.

[0053] The height adjustment mechanism 5 includes an adjustable knob 5-1 and an adjustment backing plate 5-2. The adjustment backing plate 5-2 is provided with an adjustment backing plate hole 5-3, and the hole and shaft specifications are the same. The adjustable knob 5-1 cooperates with the adjustment backing plate 5-2, and the adjustment backing plate 5-2 is arranged in the actuator fixing groove 4-6. The assembly method of the adjustable knob 5-1, the adjustment backing plate 5-2 and the nozzle fixing body 4 is as Figure 7 shown. The adjustable knob 5-1 sequentially passes through the adjustable knob threaded hole 4-2 preset in the nozzle fixing body 4 and the adjustment backing plate hole 5-3. The upper end surface of the adjustment backing plate 5-2 contacts the porous PVC gel flexible actuator 3, and the lower end hole cooperates with the adjustable knob 5-1. When the adjustable knob 5-1 rotates in the adjustable knob threaded hole 4-2, the adjustable knob 5-1 makes an axial displacement relative to the nozzle moving body 1, thereby pushing the adjustment backing plate 5-2 to move up and down, adjusting the gap between the actuator and the nozzle fixing part, adjusting the height of the actuator, ensuring that the moving body remains horizontal in the initial state, and achieving the purpose of adjusting the up and down position of the flexible actuator 3.

[0054] The connecting hinge 2 includes upper and lower parts. The upper part is provided with three specific structures: a hinge ball head 2-3, a hinge ball rod 2-4, and a hinge upper base 2-1 connected in sequence. The lower part is provided with a hinge lower base 2-2, and the inner wall 2-5 of the spherical groove is embedded in the hinge lower base 2-2. The connecting hinge 2 converts the linear displacement of the flexible actuator into the swing of the nozzle movable body. The hinge ball head 2-3 cooperates with the inner wall 2-5 of the spherical groove in the lower part and has only three rotational degrees of freedom. Through relative rotation, the displacement output by the actuator can be converted into the swing of the movable body. The hinge ball head 2-3 is not a complete spherical structure. On the premise of ensuring the rotational function, the thickness of the hinge lower base is reduced, leaving more space for the actuator and increasing the output performance of the actuator. The hinge ball rod 2-4 pulls the hinge ball head 2-3 and the hinge upper base 2-1 apart by a certain distance, providing space for the relative rotation of the upper and lower parts. The hinge upper base 2-1 increases the contact area between the connecting hinge and the connecting hinge base, improving the structural stability.

[0055] Working mode:

[0056] First, the height adjustment mechanism 5 rotates the adjustable knob 5-1 to push the adjustment pad 5-2 to finely adjust the installation height of the actuator 3, compensating for the assembly error, ensuring that the initial state of the movable body 1 is horizontal, and avoiding uneven loading. After the porous PVC gel actuator 3 is powered on, under the action of the electric field, the plasticizer molecules inside it migrate directionally, causing the gel to creep directionally towards the anode side. Part of the volume enters the internal pores of the wire mesh, and the overall axial compression deformation occurs.

[0057] The compression deformation of the actuator is transmitted through the connecting hinge (as Figure 9 shown): The top pushes the hinge lower base 2-2 to move upward, driving the hinge ball head 2-3 to rotate in the spherical groove 2-5; the hinge ball rod 2-4 transmits the rotation to the base 1-3 of the nozzle movable body 1, driving the movable body to deflect around the cross-axis swing center (deflecting around the geometric center of the cross-axis mechanism), converting the linear displacement of the actuator into the swing of the movable body, and realizing the pitch / yaw swing of the nozzle expansion section 1-2.

[0058] The cross-axis mechanism 6 is matched with the cross-axis sub-axis 1-4 and the cross-axis female hole 6-2 at right angles, restricting the movable body to only retain two rotational degrees of freedom; the cross-axis hole 4-4 of the nozzle fixed body 4 is coaxially assembled with the mother axis 6-1 to ensure that the swing center position is fixed and the thrust vector direction is accurately controllable.

[0059] That is:

[0060] Power-on drive: Apply voltage → actuator contracts → hinge ball head rotates → movable body deflects → nozzle thrust direction changes;

[0061] Power-off reset: Voltage is withdrawn → gel returns to its original shape → hinge rotates in the opposite direction → movable body returns to its original position → thrust direction resets.

[0062] Finally, under the drive of the porous tube PVC gel flexible actuator 3, the nozzle movable body always swings with the geometric center of the cross shaft as the swing center, and only retains the degrees of freedom of rotation of the two axes orthogonal in the horizontal direction, improving the maneuverability of the aircraft.

[0063] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, such as the generation of bubbles by micro-structure casting, the drive, connection, and integrated design concept of the nozzle throat, the optimization of the flexible vector nozzle structure, and the simple adjustment of the geometric parameters of parts such as the nozzle movable body. These improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of porous PVC gel, characterized in that, It includes the following steps: 1) Weigh three chemical reagents, namely polyvinyl chloride, plasticizer and tetrahydrofuran, according to a certain mass ratio; 2) Mix and stir. Mix the above three reagents in the same conical flask and stir well; 3) Pour the evenly stirred transparent solution onto a special petri dish. The special petri dish includes a stainless-steel petri dish and waterproof sandpaper. Fix the sandpaper at the bottom of the petri dish so that the transparent solution contacts the rough surface of the sandpaper when the gel is poured; 4) Place the above petri dish in a fume hood and let it volatilize naturally until the tetrahydrofuran completely volatilizes, obtaining a porous PVC gel with a rough structure on the surface, while there are some bubbles preserved inside the gel and the structural stiffness is lower.

2. A porous PVC gel flexible actuator, characterized in that, It includes a porous PVC gel prepared by the preparation method of the porous PVC gel as described in Claim 1, and also includes a driving unit cathode and a driving unit anode. They are combined in the arrangement order of "anode - porous PVC gel - cathode - porous PVC gel - anode... anode" to form the porous PVC gel flexible actuator.

3. The porous PVC gel flexible actuator according to claim 2, characterized in that, The cathode is a copper foil and the anode is a wire mesh.

4. The porous PVC gel flexible actuator according to claim 3, wherein When the power supply is energized, a part of the volume of the PVC gel is embedded into the gaps of the wire mesh grid, and the distance between the copper foil and the wire mesh is shortened; When the power supply is disconnected, the PVC gel returns to its original position and the distance between the copper foil and the wire mesh is restored. The change in the distance between the electrodes is accumulated on the porous PVC gel flexible actuator, and the overall manifestation is the contraction and restoration in the thickness direction of the actuator.

5. A flexible vector nozzle based on a porous polyvinyl chloride gel actuator, characterized in that, It includes a nozzle moving body (1), a porous PVC gel flexible actuator (3) and a nozzle fixing body (4); The lower end of the porous PVC gel flexible actuator (3) is embedded in the actuator fixing groove (4-6) of the nozzle fixing body (4), and the upper end is connected to the nozzle moving body (1) through a connecting member, converting the linear displacement of the actuator into the swing of the moving body.

6. The flexible vector nozzle based on the porous polyvinyl chloride gel actuator according to claim 5, wherein The connecting member is a connecting hinge (2), which includes two parts, the upper part includes a hinge ball head (2-3), a hinge ball rod (2-4) and a hinge upper base (2-1) connected in sequence, the lower part includes a hinge lower base (2-2), and the inner wall of the spherical groove (2-5) is embedded in the hinge lower base (2-2). The hinge ball head (2-3) cooperates with the inner wall of the spherical groove (2-5) and has three degrees of freedom of rotation. Through relative rotation, the displacement output by the actuator can be converted into the swing of the moving body.

7. The flexible vector nozzle based on the porous polyvinyl chloride gel actuator according to claim 6, characterized in that, The upper end of the porous PVC gel flexible actuator (3) is fixedly connected to the hinge lower base (2-2) of the connecting hinge (2). A hinge base (1-3) is provided on the nozzle moving body (1). The connecting hinge (2) is fixed on the connecting hinge base (1-3) of the nozzle moving body (1) through the hinge upper base (2-1).

8. The flexible vector nozzle based on the porous polyvinyl chloride gel actuator according to claim 5, characterized in that, The flexible vector nozzle further includes a height adjustment mechanism (5). The height adjustment mechanism (5) includes an adjustable knob (5-1) and an adjustment backing plate (5-2). The adjustment backing plate (5-2) is arranged in the driver fixing groove (4-6) and is provided with an adjustment backing plate hole (5-3). Correspondingly, an adjustable knob threaded hole (4-2) is provided on the driver fixing groove (4-6). The lower end of the porous PVC gel flexible driver (3) contacts the adjustment backing plate (5-2). When the adjustable knob (5-1) rotates in the adjustable knob threaded hole (4-2), the adjustable knob (5-1) makes an axial displacement relative to the nozzle moving body (1), thereby pushing the adjustment backing plate (5-2) to move up and down. By pressing the adjustment backing plate (5-2) of the height adjustment mechanism (5), the initial installation clearance is adjusted by the adjustable knob (5-1).

9. The flexible vector nozzle based on the porous polyvinyl chloride gel actuator according to claim 5, characterized in that A cross-axis mechanism (6) is provided at the throat of the flexible vector nozzle. The nozzle moving body (1) and the nozzle fixed body (4) are assembled based on the cross-axis mechanism (6). The cross-axis mechanism (6) includes a cross-axis female shaft (6-1), a cross-axis female hole (6-2) and a cross-axis female. Correspondingly, a cross-axis male shaft (1-4) is provided at the throat of the nozzle moving body (1), and a cross-axis hole (4-4) is preset on the nozzle fixed body (4). The cross-axis female hole (6-1) is coaxially fitted with the cross-axis hole (4-4), and the cross-axis male shaft (1-4) is coaxially fitted with the cross-axis female hole (6-1), restricting all other degrees of freedom of the nozzle moving body (1) except for deflection around the geometric center of the cross-axis mechanism (6), thus realizing vector control.

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