Axisymmetric air inlet throat area conversion structure

Abstract

The invention discloses an axial symmetry air inlet channel throat area conversion structure which comprises an air inlet channel throat adjusting mechanism and a center cone outer skin. The air inlet channel throat adjusting mechanism comprises a fixed block fixed to the position, close to the inner wall of the throat, of the air inlet channel, a sliding push rod assembly installed in the fixed block and a supporting assembly, the fixed block is fixed to the position, close to the inner wall of the throat, of the air inlet channel, and a movable groove, a threaded groove and an adjusting hole are sequentially formed in the fixed block from an inlet of the air inlet channel to the throat. The first sliding disc and the second sliding disc are pushed and pulled through the sliding push rod assembly so that the large supporting plate assembly and the small supporting plate assembly can be unfolded and folded in sequence, then the hollow compression section on the center cone outer skin is expanded, the hollow connecting section is driven to slide on the fixing block, the throat area of the air inlet channel is adjusted, and then the air inlet flow is controlled; the air inlet channel can stably work in a wide flight Mach number range, and meanwhile the structure is simple, practical and convenient to control.

Description

Technical Field

[0001] The present invention relates to the technical field of ramjet inlets, and particularly to an axisymmetric inlet throat area conversion structure. Background Art

[0002] Future aerospace vehicles are capable of spanning a wide range of speeds (0 - 8 Mach) and altitudes (0 - 50 km), enabling them to perform various missions under different conditions, including taking off from the ground, achieving hypersonic flight, entering orbit, or returning to the ground. To meet such broad operating requirements, the vehicle requires a stable and efficient propulsion system that can adapt to various environmental conditions.

[0003] Currently, to address this challenge, multi - mode air - breathing engines are commonly used. These engines combine the characteristics of rockets, turbojets, and ramjets to provide continuous power support throughout the flight envelope. For example, the rocket - based combined cycle engine includes several key modes, such as the ejector mode, subsonic combustion ramjet mode, supersonic combustion ramjet mode, and pure rocket mode. Since the requirements for the engine flow path design in these different modes vary significantly and even conflict with each other, the use of variable - structure inlets has become an effective solution. By changing the geometry of the inlet to adapt to the engine's requirements at different stages, the entire propulsion system can operate efficiently over a wide range of speeds and altitudes. Most of the current inlet profile deformation adjustment structures are applied to rectangular - section inlets and are not suitable for circular - section inlets. Using them on circular - section inlets affects the engine's performance and reduces its operating efficiency.

[0004] To address the above - mentioned deficiencies in the prior art, an axisymmetric inlet throat area conversion structure needs to be designed. Summary of the Invention

[0005] The purpose of the present invention is to propose an axisymmetric inlet throat area conversion structure to address the drawbacks existing in the prior art.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an axisymmetric air inlet throat area conversion structure, which is fixed on the inner wall of the air inlet, including an air inlet throat adjustment mechanism and a central cone outer skin; the air inlet throat adjustment mechanism includes a fixed block fixed on the inner wall of the air inlet near the throat, a sliding push rod assembly installed in the fixed block, and a support assembly, the fixed block is fixed on the inner wall of the air inlet throat near the air inlet, and its interior is sequentially provided with a movable groove, a threaded groove and an adjustment hole in the order from the air inlet entrance to the throat; the central cone outer skin includes a solid fixed section, a hollow compression section and a hollow connecting section, the solid fixed section is conically arranged at the air inlet entrance, its large mouth end is riveted to one end of the hollow compression section, the other end of the hollow compression section is riveted to one end of the hollow connecting section, the other end of the hollow connecting section is sleeved on the fixed block, and the hollow compression section includes a plurality of elastic arc surfaces and telescopic concave strips riveted on the elastic arc surfaces for connecting the plurality of elastic arc surfaces, The telescopic concave strip includes an expanded state and a retracted state. In the expanded state, it is an arc-shaped and the arc surface is flush with the arc surface of the elastic arc surface. In the retracted state, it is a triangle protruding toward the support assembly, so that the hollow compression section can be expanded to reduce the throat area of ​​the air inlet duct and retracted to expand the throat area of ​​the air inlet duct; the support assembly includes a connecting rod assembly and a fixed disk, a first sliding disk, a second sliding disk and a threaded disk arranged on the sliding push rod assembly in sequence from the air inlet entrance to the throat; the connecting rod assembly includes a large support plate assembly and a small support plate assembly, the large support plate assembly is hinged to the fixed disk and the first sliding disk, the small support plate assembly is hinged to the fixed disk and the second sliding disk, the sliding push rod assembly pushes and pulls the first sliding disk and the second sliding disk so that the large support plate assembly and the small support plate assembly respectively realize the expanded and retracted states, thereby opening the hollow compression section on the outer skin of the center cone, driving the hollow connecting section to slide on the fixed block, and the threaded disk passes through the movable groove and is threadedly connected to the threaded groove.

[0007] Furthermore, the large support plate assembly includes a plurality of first connecting rods, a second connecting rod, a large triangular joint and a large support plate, the large triangular joint including a flat end and two round ends; one end of the plurality of first connecting rods is evenly distributed near the edge of the fixed plate and hinged thereto, and the other end is hinged to a flat end of the large triangular joint, a round end of the large triangular joint is hinged to one end of the second connecting rod, and the other round end is hinged to the large support plate, and the other end of the second connecting rod is evenly distributed near the edge of the first sliding plate and hinged thereto.

[0008] Furthermore, the small support plate assembly includes a plurality of third connecting rods, a fourth connecting rod, a small triangular joint and a small support plate, the small triangular joint includes a flat end and two round ends; one end of the third connecting rod is evenly distributed near the edge of the fixed plate and hinged thereto, the other end is hinged to a flat end of the small triangular joint, a round end of the small triangular joint is hinged to one end of the fourth connecting rod, the other round end is hinged to the small support plate, and the other end of the fourth connecting rod is evenly distributed near the edge of the second sliding plate and hinged thereto.

[0009] Furthermore, the sliding push rod assembly includes a fixed screw, a plurality of sliding rods and an electric push rod; one end of the fixed screw is threadedly connected to the solid fixed section, and the other end is threadedly connected to the fixed disk. One end of the sliding rod is fixedly connected to the fixed disk, penetrates through the first sliding disk and the second sliding disk, and the other end is fixedly connected to the threaded disk. The push rod of the electric push rod sequentially penetrates through the adjustment hole, the threaded disk, the second sliding disk and the first sliding disk, and a first limit nut is arranged on the extended part. On the push rod of the electric push rod, a first push nut, a second limit nut and a second push nut are sequentially fixed near the first limit nut. The first limit nut and the first push nut are respectively located on both sides of the first sliding disk, and the second limit nut and the second push nut are respectively located on both sides of the second sliding disk. Moreover, the distance between the first limit nut and the first push nut corresponds to the moving stroke of the large support plate assembly, and the distance between the second limit nut and the second push nut corresponds to the moving stroke of the small support plate assembly.

[0010] Furthermore, a gap is provided between the large support plate and the small support plate, and the length of the fourth connecting rod is greater than the length of the second connecting rod, so that the moving stroke of the small support plate assembly is less than the moving stroke of the large support plate assembly.

[0011] Furthermore, a plurality of rotating shaft seats are threadedly connected to the fixed disk, the first sliding disk and the second sliding disk. The first connecting rod, the second connecting rod, the third connecting rod and the fourth connecting rod are respectively hinged to the fixed disk, the first sliding disk and the second sliding disk through the rotating shaft seats.

[0012] Furthermore, the telescopic concave strip is made of rubber, and both the hollow compression section and the hollow connection section are made of elastic metal.

[0013] Furthermore, the shape of the fixed block is adapted to the inner wall shape of the air inlet passage, the shapes of the hollow compression section and the hollow connection section are both adapted to the inner wall shape of the air inlet passage, the shape of the large support plate is adapted to the inner wall shape of the hollow compression section, and the shape of the small support plate is adapted to the shape after the telescopic concave strip is unfolded.

[0014] Furthermore, limit protrusions are provided on the round ends at the joints of the large triangular joint and the second connecting rod, and on the round ends at the joints of the small triangular joint and the fourth connecting rod.

[0015] Beneficial effects:

[0016] 1. The present invention utilizes a sliding push rod assembly to push and pull a first sliding disk and a second sliding disk, enabling the large support plate assembly and the small support plate assembly to be unfolded and contracted successively, thereby expanding the hollow compression section on the outer skin of the central cone, driving the hollow connection section to slide on the fixed block to adjust the throat area of the air inlet duct, and further controlling the air intake flow rate. The air inlet duct can operate stably within a relatively wide range of flight Mach numbers. It can make up for the support gap after the change of the throat area of the circumferential air inlet duct, achieve a smooth transition between different unfolded and contracted states, and continuously and stably operate before and after the change of the air intake throat area. By setting an elastic arc surface and telescopic concave strips, dual-state reversible adjustment is realized. At the same time, the control device has a simple and practical structure, simple and convenient control, and high feasibility in engineering applications.

[0017] 2. The present invention arranges the large support plate assembly and the small support plate assembly to be unfolded and contracted successively, so that there is no interference between the unfolding and contraction of the large support plate assembly and the small support plate assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a three-dimensional structural schematic diagram of the present invention installed in the air inlet duct;

[0019] Figure 2 is a three-dimensional structural schematic diagram of the air inlet duct throat area conversion structure of the present invention;

[0020] Figure 3 is a three-dimensional structural schematic diagram of the fixed block and the interior of the outer skin of the central cone of the present invention;

[0021] Figure 4 is a three-dimensional structural schematic diagram of the support assembly of the present invention;

[0022] Figure 5 is a connection schematic diagram of the large support plate assembly and the small support plate assembly of the present invention;

[0023] Figure 6 is a three-dimensional structural schematic diagram of the sliding push rod assembly of the present invention;

[0024] Figure 7 is a three-dimensional structural schematic diagram of the contracted state of the large support plate assembly and the small support plate assembly of the present invention;

[0025] Figure 8 is a schematic diagram of the contracted state after the large support plate assembly and the small support plate assembly of the present invention are assembled with the outer skin of the central cone;

[0026] Figure 9 is a three-dimensional structural schematic diagram of the unfolded state of the large support plate assembly and the small support plate assembly of the present invention;

[0027] Figure 10 is a schematic diagram of the unfolded state after the large support plate assembly and the small support plate assembly of the present invention are assembled with the outer skin of the central cone;

[0028] In the figure:

[0029] 11. Fixed block; 12. Sliding push rod assembly; 121. Fixed screw; 122. Sliding rod; 123. Electric push rod; 13. Support assembly; 131. Fixed disk; 132. First sliding disk; 133. Second sliding disk; 134. Threaded disk; 135. Large support plate assembly; 1351. First connecting rod; 1352. Second connecting rod; 1353. Large triangular joint; 1354. Large support plate; 136. Small support plate assembly; 1361. Third connecting rod; 1362. Fourth connecting rod; 1363. Small triangular joint; 1364. Small support plate; 2. Center cone outer skin; 21. Solid fixed section; 22. Hollow compression section; 22a. Elastic arc surface; 22b. Telescopic concave strip; 23. Hollow connection section. Detailed implementation manners

[0030] 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] Referring to Figures 1-10 , in order to achieve the above object, the present invention adopts the following technical solutions: An axisymmetric inlet throat area conversion structure, as Figures 2-3As shown in the figure, it is fixed on the inner wall of the intake duct and includes an intake duct throat adjustment mechanism and the outer skin 2 of the center cone; the intake duct throat adjustment mechanism includes a fixed block 11 fixed on the inner wall of the intake duct near the throat, a sliding push rod assembly 12 installed in the fixed block 11, and a support assembly 13. The fixed block 11 is fixed on the inner wall of the intake duct near the throat. The shape of the fixed block 11 is adapted to the shape of the inner wall of the intake duct. An activity groove, a threaded groove, and an adjustment hole are successively formed inside it in the order from the intake duct inlet to the throat; the outer skin 2 of the center cone includes a solid fixed section 21, a hollow compression section 22, and a hollow connection section 23. The solid fixed section 21 is conical and arranged at the intake duct inlet. Its large end is riveted to one end of the hollow compression section 22. The other end of the hollow compression section 22 is riveted to one end of the hollow connection section 23. The other end of the hollow connection section 23 is sleeved on the fixed block 11. The shapes of the hollow compression section 22 and the hollow connection section 23 are both adapted to the shape of the inner wall of the intake duct. And the hollow compression section 22 includes a number of elastic arc surfaces 22a and telescopic concave strips 22b riveted on the elastic arc surfaces 22a for connecting a number of elastic arc surfaces 22a. The telescopic concave strips 22b are made of rubber. The telescopic concave strips 22b include an unfolded state and a contracted state. The unfolded state is circular arc-shaped and the arc surface is flush with the arc surface of the elastic arc surface 22a. The contracted state is a triangle protruding towards the support assembly 13, so that the hollow compression section 22 can expand to reduce the area of the intake duct throat and contract to increase the area of the intake duct throat. Both the hollow compression section 22 and the hollow connection section 23 are made of elastic metal; As Figure 4 shown in the figure, the support assembly 13 includes a connecting rod assembly and a fixed disk 131, a first sliding disk 132, a second sliding disk 133, and a threaded disk 134 that are successively arranged on the sliding push rod assembly 12 in the order from the intake duct inlet to the throat; the connecting rod assembly includes a large support plate assembly 135 and a small support plate assembly 136. The large support plate assembly 135 is hinged to the fixed disk 131 and the first sliding disk 132. The small support plate assembly 136 is hinged to the fixed disk 131 and the second sliding disk 133. The sliding push rod assembly 12 pushes and pulls the first sliding disk 132 and the second sliding disk 133 so that the large support plate assembly 135 and the small support plate assembly 136 respectively achieve the unfolded and contracted states, and then expand the hollow compression section 22 on the outer skin 2 of the center cone, driving the hollow connection section 23 to slide on the fixed block 11. The unfolding and contraction of the large support plate assembly 135 and the small support plate assembly 136 do not interfere with each other during the successive unfolding and contraction. The threaded disk 134 passes through the activity groove and is threadedly connected to the threaded groove.

[0032] Install this device in the body. By using the sliding push rod assembly 12 to push and pull the first sliding disk 132 and the second sliding disk 133, the large support plate assembly 135 and the small support plate assembly 136 are respectively expanded and contracted successively, so as to expand the hollow compression section 22 on the central cone outer skin 2, drive the hollow connection section 23 to slide on the fixed block 11, adjust the inlet throat area, and then control the inlet air flow, so that the inlet can work stably within a wide range of flight Mach numbers. Compared with other inlet throat adjustment mechanisms, the present invention can make up for the support gap after the change of the inlet throat area of the circumferential inlet, has the advantages of realizing a smooth transition between different expanded and contracted states and continuously stable operation before and after the change of the inlet throat area, and realizes double-state reversible adjustment by setting the elastic arc surface 22a and the telescopic concave strip 22b. It solves the limitation that the current inlet profile adjustment structure is only applicable to the rectangular cross-section inlet. At the same time, the control device has a simple and practical structure, simple and convenient control, and high engineering application feasibility.

[0033] As Figures 4-5 shown, among them, the large support plate assembly 135 is used to expand the hollow compression section 22 on the central cone outer skin 2. The large support plate assembly 135 includes a number of first connecting rods 1351, second connecting rods 1352, large triangular joints 1353 and a large support plate 1354. The large triangular joint 1353 includes a flat end and two round ends. The shape of the large support plate 1354 is adapted to the inner wall shape of the hollow compression section 22; one ends of a number of first connecting rods 1351 are evenly distributed and hinged to the fixed disk 131 near the edge, and the other ends are hinged to a flat end of the large triangular joint 1353. One round end of the large triangular joint 1353 is hinged to one end of the second connecting rod 1352, and the other round end is hinged to the large support plate 1354. The other ends of the second connecting rods 1352 are evenly distributed and hinged to the first sliding disk 132 near the edge.

[0034] The small support plate assembly 136 is used to support the telescopic concave strip 22b in the hollow compression section 22 of the central cone outer skin 2. The small support plate assembly 136 includes a number of third connecting rods 1361, fourth connecting rods 1362, small triangular joints 1363 and small support plates 1364. The small triangular joint 1363 includes a flat end and two round ends. The shape of the small support plate 1364 is adapted to the shape of the telescopic concave strip 22b after expansion. One end of the third connecting rod 1361 is evenly distributed and hinged to the fixed disk 131 near the edge, and the other end is hinged to a flat end of the small triangular joint 1363. One round end of the small triangular joint 1363 is hinged to one end of the fourth connecting rod 1362, and the other round end is hinged to the small support plate 1364. The other end of the fourth connecting rod 1362 is evenly distributed and hinged to the second sliding disk 133 near the edge. Limiting protrusions are provided on the round ends at the connection of the large triangular joint 1353 and the second connecting rod 1352, and on the round ends at the connection of the small triangular joint 1363 and the fourth connecting rod 1362. One end of the large triangular joint 1353 and the small triangular joint 1363 is set as a flat end, and the other two ends are round ends. The limiting protrusions are arranged to form a constraint with the round rod end faces of the second connecting rod 1352 and the fourth connecting rod 1362, which can prevent getting stuck at a dead point or the rod from folding back during the movement process.

[0035] Moreover, in order to prevent interference between the large support plate 1354 and the small support plate 1364 during the movement process, a gap is provided between the large support plate 1354 and the small support plate 1364. The length of the fourth connecting rod 1362 is greater than the length of the second connecting rod 1352, so that the movement stroke of the small support plate assembly 136 is less than the movement stroke of the large support plate assembly 135. It can realize the priority to push the large support plate assembly 135 to expand, so that the force acts on the elastic metal of the hollow compression section 22 of the central cone outer skin 2, prompting the folded telescopic concave strip 22b to expand. Then the small support plate assembly 136 expands to support the telescopic concave strip 22b, completing the expansion of the hollow compression section 22 of the central cone outer skin 2. When contraction is required, the small support plate assembly 136 will contract first, and then the large support plate assembly 135 will contract, so that there will be no interference in the expansion and contraction of the large support plate assembly 135 and the small support plate assembly 136.

[0036] Such as Figure 6As shown in the figure, the sliding push rod assembly 12 includes a fixed screw 121, several sliding rods 122, and an electric push rod 123. One end of the fixed screw 121 is threadedly connected to the solid fixed section 21, and the other end is threadedly connected to the fixed disk 131 to ensure its stability. One end of the sliding rod 122 is fixedly connected to the fixed disk 131, penetrates through the first sliding disk 132 and the second sliding disk 133, enabling the first sliding disk 132 and the second sliding disk 133 to slide on the sliding rod 122, and the other end is fixedly connected to the threaded disk 134. The push rod of the electric push rod 123 sequentially penetrates through the adjustment hole, the threaded disk 134, the second sliding disk 133, and the first sliding disk 132, and a first limit nut is provided on the extended part. A first push nut, a second limit nut, and a second push nut are sequentially arranged on the push rod of the electric push rod 123 near the first limit nut. The first limit nut, the first push nut, the second limit nut, and the second push nut are all axially positioned with the push rod of the electric push rod 123 by using set screws, facilitating the adjustment of the positions of the four nuts. The first limit nut and the first push nut are respectively located on both sides of the first sliding disk 132, the second limit nut and the second push nut are respectively located on both sides of the second sliding disk 133, and the distance between the first limit nut and the first push nut corresponds to the moving stroke of the large support plate assembly 135, and the distance between the second limit nut and the second push nut corresponds to the moving stroke of the small support plate assembly 136.

[0037] For the convenience of hinging, several rotating shaft seats are threadedly connected to the fixed disk 131, the first sliding disk 132, and the second sliding disk 133. The first connecting rod 1351, the second connecting rod 1352, the third connecting rod 1361, and the fourth connecting rod 1362 are all hinged to the fixed disk 131, the first sliding disk 132, and the second sliding disk 133 through the rotating shaft seats.

[0038] The specific working principle of the present invention is as follows:

[0039] As Figures 7-8 shown in the figure, when the throat area of the intake passage needs to be increased, the electric push rod 123 is pulled back. Under the action of the elastic deformation force of the outer skin 2 of the center cone, it is urged that the first push nut always abuts against the first sliding disk 132, and the second push nut always abuts against the second sliding disk 133 and they are retracted together until after retracting to the original position of the large support plate assembly 135, the electric push rod 123 continues to be pulled back and move a certain stroke, making the first limit nut contact the first sliding disk 132, and the second limit nut contact the second sliding disk 133, pulling the first sliding disk 132 and the second sliding disk 133 to ensure that they return to the original position, completing all the contraction work, as Figure 8 shown in the figure.

[0040] As Figures 9-10As shown in the figure, when the throat area of the inlet needs to be reduced, the electric push rod 123 is pushed to make the first push nut on its push rod contact the first sliding disk 132, prompting the large support plate assembly 135 to unfold. The outer skin 2 of the center cone expands outward under the action of the large support plate 1354, and the hollow compression section 22 undergoes elastic deformation, causing the elastic arc surface 22a to slowly unfold and drive the telescopic concave strip 22b to unfold accordingly. After the push rod of the electric push rod 123 moves a certain distance, the second push nut contacts the second sliding disk 133, pushing the small support plate assembly 136 to unfold. Since the length of the fourth connecting rod 1362 in the small support plate assembly 136 is greater than the length of the second connecting rod 1352 in the large support plate assembly 135, it can achieve the same support height with less travel, realizing the support after the telescopic concave strip 22b unfolds. Along with the increase in the hollow compression section 22 of the outer skin 2 of the center cone, the outer skin 2 of the center cone needs to move axially. The hollow connecting section 23 is slidably connected to the fixed block 11 to compensate for this part of the travel. After the set travel of the electric push rod 123 ends, all the unfolding work can be completed simultaneously, as Figure 10 shown

[0041] In actual use, due to the possible dead point effect during the movement of the large support plate assembly 135 or the small support plate assembly 136, or excessive friction at each hinge and sliding point, the first push nut and the second push nut may not always press against the first sliding disk 132 and the second sliding disk 133. Therefore, during the retraction of the electric push rod 123, the first limit nut pulls the first sliding disk 132 to move. After moving a certain distance, the second limit nut pulls the second sliding disk 133 to move, resulting in the phenomenon that the large support plate assembly 135 contracts first and the small support plate assembly 136 contracts later.

[0042] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An axisymmetric inlet throat area conversion structure fixed on the inner wall of the inlet duct, characterized in that: The invention comprises an air inlet throat adjustment mechanism and a center cone outer skin (2); the air inlet throat adjustment mechanism comprises a fixed block (11) fixed on the inner wall of the air inlet near the throat, a sliding push rod assembly (12) installed in the fixed block (11) and a support assembly (13); the fixed block (11) is fixed on the inner wall of the air inlet near the throat, and a movable groove, a threaded groove and an adjustment hole are arranged in the fixed block (11) in sequence from the air inlet entrance to the throat; The central cone outer skin (2) comprises a solid fixed section (21), a hollow compression section (22) and a hollow connecting section (23). The solid fixed section (21) is conically arranged at the inlet of the air inlet, and its large mouth end is riveted to one end of the hollow compression section (22). The other end of the hollow compression section (22) is riveted to one end of the hollow connecting section (23). The other end of the hollow connecting section (23) is sleeved on the fixed block (11), and the hollow compression section (22) comprises a plurality of elastic The arc surface (22a) and a telescopic concave strip (22b) riveted on the elastic arc surface (22a) for connecting a plurality of elastic arc surfaces (22a), the telescopic concave strip (22b) comprising an expanded state and a contracted state, the expanded state being an arc shape with the arc surface flush with the arc surface of the elastic arc surface (22a), and the contracted state being a triangle protruding toward the support assembly (13), so that the hollow compression section (22) can be expanded to reduce the throat area of ​​the air inlet duct and contracted to expand the throat area of ​​the air inlet duct; The support assembly (13) comprises a connecting rod assembly and a fixed disk (131), a first sliding disk (132), a second sliding disk (133) and a threaded disk (134) which are arranged on the sliding push rod assembly (12) in sequence from the inlet to the throat; the connecting rod assembly comprises a large support plate assembly (135) and a small support plate assembly (136), wherein the large support plate assembly (135) is hinged to the fixed disk (131) and the first sliding disk (132), and the small support plate assembly (136) is hinged to the fixed disk (131) and the first sliding disk (132). ) is hinged with the fixed plate (131) and the second sliding plate (133), and the sliding push rod assembly (12) pushes and pulls the first sliding plate (132) and the second sliding plate (133) so that the large support plate assembly (135) and the small support plate assembly (136) can be respectively expanded and contracted, thereby expanding the hollow compression section (22) on the outer skin (2) of the center cone, driving the hollow connection section (23) to slide on the fixed block (11), and the threaded plate (134) passes through the movable groove and is threadedly connected with the threaded groove.

2. The inlet throat area conversion structure according to claim 1, characterized in that: The large support plate assembly (135) includes a plurality of first connecting rods (1351), a second connecting rod (1352), a large triangular joint (1353) and a large support plate (1354), wherein the large triangular joint (1353) includes a flat end and two round ends; one end of the plurality of first connecting rods (1351) is evenly distributed near the edge of the fixed plate (131) and is hinged thereto, and the other end is hinged to a flat end of the large triangular joint (1353); one round end of the large triangular joint (1353) is hinged to one end of the second connecting rod (1352), and the other round end is hinged to the large support plate (1354); the other end of the second connecting rod (1352) is evenly distributed near the edge of the first sliding plate (132) and is hinged thereto.

3. The inlet throat area conversion structure according to claim 2, characterized in that: The small support plate assembly (136) includes a plurality of third connecting rods (1361), a fourth connecting rod (1362), a small triangular joint (1363) and a small support plate (1364), wherein the small triangular joint (1363) includes a flat end and two round ends; one end of the third connecting rod (1361) is evenly distributed near the edge of the fixed plate (131) and is hinged thereto, and the other end is hinged to a flat end of the small triangular joint (1363); one round end of the small triangular joint (1363) is hinged to one end of the fourth connecting rod (1362), and the other round end is hinged to the small support plate (1364); the other end of the fourth connecting rod (1362) is evenly distributed near the edge of the second sliding plate (133) and is hinged thereto.

4. The inlet throat area conversion structure according to claim 1, characterized in that: The sliding push rod assembly (12) comprises a fixed screw rod (121), a plurality of sliding rods (122) and an electric push rod (123); one end of the fixed screw rod (121) is threadedly connected to the solid fixed section (21), and the other end is threadedly connected to the fixed disk (131); one end of the sliding rod (122) is fixedly connected to the fixed disk (131), passes through the first sliding disk (132) and the second sliding disk (133), and the other end is fixedly connected to the threaded disk (134); the push rod of the electric push rod (123) passes through the adjustment hole, the threaded disk (134), the second sliding disk (133) and the first sliding disk (132) in sequence. A first limiting nut is provided on the extended portion, and a first pushing nut, a second limiting nut and a second pushing nut are fixed in sequence on the push rod of the electric push rod (123) near the first limiting nut. The first limiting nut and the first pushing nut are respectively located on both sides of the first sliding disk (132), and the second limiting nut and the second pushing nut are respectively located on both sides of the second sliding disk (133). The distance between the first limiting nut and the first pushing nut corresponds to the moving stroke of the large support plate assembly (135), and the distance between the second limiting nut and the second pushing nut corresponds to the moving stroke of the small support plate assembly (136).

5. The inlet throat area conversion structure according to claim 3, characterized in that: A gap is provided between the large support plate (1354) and the small support plate (1364), and the length of the fourth connecting rod (1362) is greater than the length of the second connecting rod (1352), so that the moving stroke of the small support plate assembly (136) is smaller than the moving stroke of the large support plate assembly (135).

6. The inlet throat area conversion structure according to claim 2, characterized in that: The fixed plate (131), the first sliding plate (132) and the second sliding plate (133) are all threadedly connected with a plurality of rotating shaft seats, and the first connecting rod (1351), the second connecting rod (1352), the third connecting rod (1361) and the fourth connecting rod (1362) are all hinged to the fixed plate (131), the first sliding plate (132) and the second sliding plate (133) through the rotating shaft seats.

7. The inlet throat area conversion structure according to claim 1, characterized in that: The telescopic groove (22b) is made of rubber, and the hollow compression section (22) and the hollow connecting section (23) are both made of elastic metal.

8. The inlet throat area conversion structure according to claim 2, characterized in that: The shape of the fixing block (11) is compatible with the shape of the inner wall of the air inlet duct, the shapes of the hollow compression section (22) and the hollow connecting section (23) are compatible with the shape of the inner wall of the air inlet duct, the shape of the large support plate (1354) is compatible with the shape of the inner wall of the hollow compression section (22), and the shape of the small support plate (1364) is compatible with the shape of the telescopic groove (22b) after expansion.

9. The inlet throat area conversion structure according to claim 3, characterized in that: A limiting protrusion is provided on the circular end of the connection between the large triangular joint (1353) and the second connecting rod (1352), and on the circular end of the connection between the small triangular joint (1363) and the fourth connecting rod (1362).

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