Super-near-distance multi-engine multi-point force transmission structure with super-large-diameter ball bottom

Abstract

The invention discloses a multi-engine multi-point force transmission structure with an ultra-large-diameter ball bottom and an ultra-close distance. The number of box bottom thrust flanges is consistent with the total number of engines and servo; the box bottom thrust flange is axially and uniformly distributed and fixedly arranged on the box bottom scalloped segment, and an annular rack lower frame is arranged on the box bottom thrust flange; a rack upper frame connected through a rod piece is arranged above the rack lower frame, engines and servo devices are installed on the rack upper frame at intervals, and the installation positions of the engines and the servo devices and the positions of two nearest box bottom thrust flanges below the engines and the servo devices form an isosceles triangle; wherein the thrust of each engine is divided into two paths through two engine thrust rods at the engine mounting position to be connected to the lower frame of the rack on two adjacent box bottom thrust flanges below, and the thrust of each servo is divided into two paths through three servo thrust rods at the servo mounting position; the two outer paths are connected to a rack lower frame connected to two box body thrust flanges below, the middle path is connected to the rack lower frame between the two box body thrust flanges, a servo thrust rod of the middle path is supported by an auxiliary support below the rack lower frame, and an anti-bending cover is fixedly arranged in the box bottom scalloped segment; and the box bottom thrust flange and the box bottom thrust flange are opposite and coaxial.

Description

Technical Field

[0001] The invention relates to a multi-point force transmission structure for multiple engines at ultra-large diameter spherical bottom (diameter greater than 5m) and ultra-close distance, belonging to the technical field of aerospace vehicle propellant tank structures. Background Art

[0002] Structural efficiency is one of the most important indicators pursued by the launch vehicle structural system. In order to improve the structural efficiency of the rocket, more and more rockets have adopted methods such as reducing the length of the shell and reducing the weight of unnecessary structural sections to reduce the rocket's takeoff weight. The propellant tank is a key component of the launch vehicle's power system and structural system. It plays the role of transmitting force, maintaining shape, storing and transporting propellants, etc., accounting for about 50-60% of the weight of the rocket body structure. The lightweight and reliability requirements of the tank are high.

[0003] Generally, the interstage of a traditional rocket is omitted, and the rocket engine is directly connected to the top of the tank bottom through a transition ring, and the engine thrust is directly transmitted by the tank bottom, so as to maximize the structural efficiency. It is known that such a technology is used to transmit the engine thrust to the ellipsoid tank bottom in a whole circle, and the ellipsoid tank bottom adopts an integrated forming bottom, and the tank bottom is partially thickened by a mold to increase the overall rigidity of the tank bottom. The disadvantage of this scheme is that it can only withstand a small engine thrust, generally a single engine; it is only suitable for tank bottoms with a small diameter, because the larger the diameter, the smaller the overall rigidity of the tank bottom. In order to meet the strength and rigidity requirements at the same time, the local thickness of the structure on the force transmission path of the tank bottom will be very large, the raw material cost and manufacturing cost will be very high, and the one-time molding has poor adaptability to other auxiliary structures. Summary of the invention

[0004] The technical problem solved by the present invention is to overcome the shortcomings of the prior art, provide a multi-point force transmission structure for multiple engines with an ultra-large diameter ball bottom and ultra-close distance, improve the force transmission efficiency of multiple engines, and reduce the raw material and manufacturing costs as much as possible.

[0005] The technical solution of the present invention is: a multi-point force transmission structure for multiple engines with super-large diameter spherical bottom and super-close distance, including: engine thrust rod, servo thrust rod, frame lower frame, box bottom thrust flange, auxiliary support, box bottom melon slice, anti-bending cover, frame upper frame;

[0006] The number of the thrust flanges at the bottom of the box is consistent with the total number of engines and servos; the axially evenly distributed and fixedly mounted on the melon flap at the bottom of the box, the annular frame bottom is mounted on the thrust flange at the bottom of the box; the frame bottom is above the frame bottom frame and is connected by rods, the engines and servos are installed on the frame bottom frame at intervals, and the installation position of each engine and servo forms an isosceles triangle with the two nearest frame bottom thrust flanges below; wherein the thrust of each engine is divided into two paths by the engine installation through two engine thrust rods and connected to the frame bottom frame on the two adjacent frame bottom thrust flanges below, and the thrust of each servo is divided into two paths by the servo installation through three servo thrust rods, the outer two paths are connected to the frame bottom frame on the two connected box body thrust flanges below, and the middle one path is connected to the frame bottom frame between the two box body thrust flanges, and the frame bottom frame where the middle servo thrust rod is located is supported by an auxiliary support, and the anti-bending cover is fixedly mounted inside the melon flap at the bottom of the box, opposite to the position of the box bottom thrust flange and the two are coaxial.

[0007] Preferably, a third rod is installed between the two engine thrust rods, the engine and the servo are connected by rods, a triangular unit is formed between the rods, and the third rod and the triangular unit are used for stiffness matching.

[0008] Preferably, the box bottom thrust flange comprises a circular flange and a dustpan-type mounting structure located at the center of the flange, and the dustpan-type mounting structure comprises two side brackets and an inclined mounting surface above the two side brackets.

[0009] Preferably, the circular flange is connected to the melon slices at the bottom of the box by welding, a central thickened area is provided on the mounting surface to increase the rigidity of the concentrated force transmission point, and a 40-45° chamfer is adopted between the central thickened area and the welding area to reduce stress concentration.

[0010] Preferably, the thrust of the engine and servo is transmitted axially from the upper frame of the frame within a smaller radius from the arrow axis to the lower frame of the frame within a larger radius through the smaller cone angle of the rod system. To improve structural efficiency, the busbar cone angle should not be greater than 30°.

[0011] Preferably, the anti-bending hood is a combined surface of a cone and a sphere, the bottom surface of the cone is welded inside the melon petals at the bottom of the box, the top of the cone is a spherical surface, the semi-cone angle of the cone is 60° to 64°, the maximum diameter of the cone is 1.2 to 1.4 times the diameter of the thrust flange weld, that is, the diameter of the circular flange, and the height of the anti-bending hood is 0.5 to 0.6 times the maximum diameter of the cone.

[0012] Preferably, the multiple box bottom melon segments are reinforced in both the circumferential and radial directions in the force transmission area, the width of the circumferential reinforcement ribs is at least 1.5 times the diameter of the box bottom thrust flange weld, and the width of the longitudinal reinforcement ribs only needs to meet the constraint conditions of the weld strength.

[0013] Preferably, the auxiliary support is a multi-rib corner box, and the direction of the ribs is parallel to the thrust direction of the engine.

[0014] Preferably, after the box bottom thrust flange is welded and the auxiliary support is bonded and assembled, the butt joint surface is milled flat at one time to ensure high-precision assembly with the lower frame of the rack, thereby achieving a force transmission effect.

[0015] The beneficial effects of the present invention compared with the prior art are:

[0016] The technical solution of the present invention is to directly connect multiple engine frames to the tank bottom. Through the integrated force transmission path design of the engine frame and the spherical tank bottom with multi-point connection, structural topology optimization and double-sided stiffness compensation design of the tank bottom, a multi-branch force transmission rod frame structure for uniforming engine thrust and servo thrust, a multi-point connection of the ultra-large diameter spherical tank bottom and a concentrated force diffusion structure are invented, thereby realizing ultra-close distance connection and force transmission between multiple engines and the ultra-large diameter and ultra-thin tank bottom.

[0017] Compared with the prior art, the present invention eliminates the transition force transmission section between the rocket engine and the tank, and adopts structural design schemes such as multi-point flange connection between the engine frame and the spherical tank bottom, auxiliary support, and double-sided stiffness compensation of the spherical bottom, which saves the weight of the connection structure and improves the structural efficiency.

[0018] The transition force transmission section in the prior art is generally an integral forged ring. The larger the tank diameter, the heavier the weight of the entire forged ring and the higher the cost. The entire tank bottom of the present invention has only a few flanges connected to the engine frame, auxiliary supports and anti-bending covers as weight increments. Compared with the forged ring, the structural weight is greatly reduced, and the flanges, auxiliary supports and anti-bending covers are all small structural parts. The manufacturing process is simple machining and sheet metal forming, and the manufacturing cost is also greatly reduced.

[0019] After the bottom of the tank is assembled, the mating surfaces of the thrust flange and the auxiliary support are milled flat at one time to ensure high-precision assembly with the engine frame. The assembly accuracy is theoretically equivalent to that of the transition force transmission section solution in the prior art, and in fact is better because the post-assembly processing can be adjusted in real time through precise measurement to compensate for the accumulated surface errors during the tank welding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 , 2 It is a schematic diagram of the structure of the present invention;

[0021] Figure 3 It is a schematic diagram of the structure of the thrust flange and anti-bending cover of the box bottom of the present invention;

[0022] Figure 4 This is a schematic diagram of the thrust flange at the bottom of the box of the present invention;

[0023] Figure 5It is a schematic diagram of the auxiliary support of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the embodiments.

[0025] The present invention eliminates the transition force transmission section between the super-large diameter rocket engine and the tank, and adopts structural design schemes such as multi-point flange connection between the engine frame and the spherical tank bottom, auxiliary support, and double-sided stiffness compensation of the spherical bottom, which saves the weight and cost of the connection structure and improves the structural efficiency. Figure 1 ~Attached Figure 5 As shown, the multi-point force transmission structure of multiple engines at an ultra-large diameter spherical bottom and an ultra-close distance is composed of the following parts: engine thrust rod 1, servo thrust rod 2, rack lower frame 3, box bottom thrust flange 4, auxiliary support 5, box bottom melon slice 6, anti-bending cover 7, and rack upper frame 8.

[0026] The engine thrust is divided into two paths by two thrust rods 1 through the frame lower frame 3 and connected to two box bottom thrust flanges 4 respectively, dispersing the thrust of one engine to two main force transmission lines. In order to match the stiffness, a third rod with a smaller diameter is installed between the two thrust rods. The angle between the third rod and the arrow axis is called the generatrix cone angle, recorded as angle 1.

[0027] The engine frame servo thrust is transmitted to the frame lower frame 3 by three servo thrust rods 2 in three ways, and is respectively connected to two box bottom thrust flanges 4 through the frame lower frame 3. The frame lower frame 3 is only in contact with the auxiliary support 5, wherein the diameter of the two thrust rods connected to the thrust flange 4 is slightly larger than the central thrust rod connected to the auxiliary support 5. While maintaining the main force transmission line, the auxiliary force transmission line is increased to improve the uniformity of the engine's force transmission to the box bottom. The angle between the central thrust rod and the arrow axis is called the generatrix cone angle, recorded as angle 2. Angle 1 and angle 2 are not necessarily equal.

[0028] The thrust flange 4 at the bottom of the box is connected to the melon slice 6 at the bottom of the box by welding. The flange 4 includes a circular flange and a dustpan-type mounting structure located at the center of the flange. The dustpan-type mounting structure includes two side brackets and an inclined mounting surface above the two side brackets. A central thickening area is set on the circular flange to improve the rigidity of the concentrated force transmission point. The central thickening area and the welding area are chamfered at an angle of 40 to 45 degrees to reduce stress concentration at the edge of the welding area. The thrust of the engine and servo is axially transmitted to the larger radius range of the lower frame of the frame through the smaller cone angle of the rod system in the upper frame of the frame within a smaller radius from the arrow axis. In order to improve the structural efficiency, the busbar cone angle should not be greater than 30 degrees.

[0029] The auxiliary support 5 only bears thrust and is connected to the box bottom melon segment 6 by bonding. The lower frame 3 of the rack is in contact with the auxiliary support 5. When the lower frame 3 of the rack is deformed by force, the auxiliary support 5 provides axial support.

[0030] The multiple box bottom melon segments 6 are reinforced in both the circumferential and radial directions in the force transmission area. The width of the circumferential reinforcement ribs is at least 1.5 times the diameter of the thrust flange 4 weld. The width of the longitudinal reinforcement ribs only needs to meet the constraint conditions of the weld strength. The thickness of the welding area is only slightly thickened to maintain the rigidity of the skeleton while meeting the weld strength conditions, thereby ensuring the overall lightweight of the melon segments.

[0031] The anti-bending cover 7 is welded and installed inside the bottom of the box, coaxial with the thrust flange 4 at the bottom of the box, and the outer surface is a combination of a cone and a sphere. The semi-cone angle α of the cone is 60-64°, and the maximum diameter D0 of the cone is optimally 1.2-1.4 times the diameter of the weld of the thrust flange 4. The height of the anti-bending cover 7 is 0.5-0.6 times the maximum diameter of the cone. This surface has a higher specific stiffness and has good anti-bending and anti-collapse effects.

[0032] The auxiliary support 5 is a multi-rib corner box, the rib direction is parallel to the engine thrust direction, and supports the lower frame 3 of the frame, while dispersing the concentrated force on the thrust flange 4 at the bottom of the box.

[0033] After the box bottom thrust flange is welded and the auxiliary support is bonded and assembled, the butt joint surface is milled flat at one time to ensure high-precision assembly with the lower frame 3 of the rack, thereby achieving a force transmission effect.

[0034] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A multi-point force transmission structure with multiple engines at super-large diameter and super-close distance at the bottom of a ball, characterized by include: Engine thrust rod, servo thrust rod, rack lower frame, box bottom thrust flange, auxiliary support, box bottom melon slice, anti-bending cover, rack upper frame; The number of the thrust flanges at the bottom of the box is consistent with the total number of engines and servos; the axially evenly distributed and fixedly mounted on the melon flap at the bottom of the box, the annular frame bottom is mounted on the thrust flange at the bottom of the box; the frame bottom is above the frame bottom frame and is connected by rods, the engines and servos are installed on the frame bottom frame at intervals, and the installation position of each engine and servo forms an isosceles triangle with the two nearest frame bottom thrust flanges below; wherein the thrust of each engine is divided into two paths by the engine installation through two engine thrust rods and connected to the frame bottom frame on the two adjacent frame bottom thrust flanges below, and the thrust of each servo is divided into two paths by the servo installation through three servo thrust rods, the outer two paths are connected to the frame bottom frame on the two connected box body thrust flanges below, and the middle one path is connected to the frame bottom frame between the two box body thrust flanges, and the frame bottom frame where the middle servo thrust rod is located is supported by an auxiliary support, and the anti-bending cover is fixedly mounted inside the melon flap at the bottom of the box, opposite to the position of the box bottom thrust flange and the two are coaxial.

2. The multi-point force transmission structure of multiple engines with super-large diameter and super-close distance at the bottom of a ball according to claim 1 is characterized by: A third rod is installed between the two engine thrust rods, the engine and the servo are connected by rods, a triangular unit is formed between the rods, and the third rod and the triangular unit are used for stiffness matching.

3. The multi-point force transmission structure of multiple engines with super-large diameter and super-close distance at the bottom of a ball according to claim 1 is characterized by: The box bottom thrust flange comprises a circular flange and a dustpan type mounting structure located at the center of the flange. The dustpan type mounting structure comprises two side brackets and an inclined mounting surface above the two side brackets.

4. The multi-point force transmission structure of multiple engines with super-large diameter and super-close distance at the bottom of a ball according to claim 3 is characterized by: The circular flange is connected to the melon slices at the bottom of the box by welding. A central thickened area is set on the installation surface to increase the rigidity of the concentrated force transmission point. The central thickened area and the welding area are chamfered at an angle of 40 to 45 degrees to reduce stress concentration.

5. The multi-point force transmission structure of multiple engines with super large diameter and super close distance at the bottom of a ball according to claim 3 is characterized by: The thrust of the engine and servo is transmitted axially in the upper frame of the frame within a smaller radius from the arrow axis through the smaller cone angle of the rod system to the larger radius range of the lower frame of the frame. In order to improve the structural efficiency, the busbar cone angle should not be greater than 30°.

6. The multi-point force transmission structure of multiple engines with super-large diameter and super-close distance at the bottom of a ball according to claim 3 is characterized by: The anti-bending hood is a combined surface of a cone and a sphere. The bottom surface of the cone is welded inside the melon segments at the bottom of the box. The top of the cone is a spherical surface. The semi-cone angle of the cone is 60° to 64°. The maximum diameter of the cone is 1.2 to 1.4 times the diameter of the thrust flange weld, that is, the diameter of the circular flange. The height of the anti-bending hood is 0.5 to 0.6 times the maximum diameter of the cone.

7. The multi-point force transmission structure of multiple engines with super-large diameter and super-close distance at the bottom of a ball according to claim 1 is characterized by: Multiple box bottom melon segments are reinforced in both circumferential and radial directions in the force transmission area. The width of the circumferential reinforcement ribs is at least 1.5 times the diameter of the box bottom thrust flange weld, and the width of the longitudinal reinforcement ribs only needs to meet the constraints of the weld strength.

8. The multi-point force transmission structure of multiple engines with super-large diameter and super-close distance at the bottom of a ball according to claim 1 is characterized by: The auxiliary support is a multi-rib corner box, and the direction of the ribs is parallel to the thrust direction of the engine.

9. The multi-point force transmission structure of multiple engines with super-large diameter and super-close distance at the bottom of a ball according to claim 1 is characterized by: After the box bottom thrust flange is welded and the auxiliary support is bonded and assembled, the docking surface is milled flat at one time to ensure high-precision assembly with the lower frame of the rack, thereby achieving a force transmission effect.

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