A spherical bellows type large angle high pressure universal joint

Abstract

The application discloses a spherical corrugated pipe type large-angle high-pressure universal joint and relates to the technical field of airplane high-pressure pipes; in order to solve the problems of small compensation angle, limited pressure resistance, poor vibration resistance and fatigue reliability of the existing flexible joint, the following technical scheme is provided: a spherical corrugated pipe is arranged, outer cylinders are symmetrically arranged at the two ends of the spherical corrugated pipe, a connecting ring is arranged on the outer cylinder, and a welding ring is movably connected to the two ends of the spherical corrugated pipe; the connecting ring is rotatably connected with the two outer cylinders through a pin shaft and is locked and fixed by connecting screws; the application can work in a high-pressure environment and has a large-angle compensation capacity; meanwhile, the application has a compact structure, good vibration resistance and fatigue resistance, adopts a full-metal structure, is resistant to high temperature and has a reduced maintenance rate.

Description

Technical Field

[0001] This invention relates to the field of high-pressure conduit technology for aircraft, specifically to a spherical corrugated pipe type high-angle universal joint. Background Technology

[0002] In modern aircraft piping systems, particularly environmental control systems (ECS), hydraulic systems, and fuel systems, flexible connections are crucial. These connections need to compensate for angular, axial, or lateral displacements caused by airframe deformation, engine vibration, thermal expansion and contraction, and installation tolerances, while maintaining reliable sealing performance under harsh conditions of high temperature and high pressure. As aircraft performance improves, the power density of their internal systems continues to increase, leading to increasingly higher operating pressures and temperatures in piping systems, which places even greater demands on flexible connection technology.

[0003] Currently, the industry mainly adopts the following technical solutions to achieve flexible pipeline connections:

[0004] Spherical joint: This joint allows the pipeline to change angles within a certain range by utilizing the relative rotation between the sphere and the shell. Its sealing is typically achieved by a sealing ring placed between the sphere and the shell. The advantage of this design is its relatively simple structure, but its angle compensation capability is limited, generally with a maximum angular displacement not exceeding 7°. More importantly, its sealing performance and structural strength are difficult to meet the requirements of high-pressure systems, limiting its application mainly to low-pressure piping systems.

[0005] Metal bellows compensators: Due to their inherent elasticity, metal bellows can absorb axial, lateral, and angular displacements in pipelines. However, under pressure, traditional unrestrained bellows generate enormous axial pressure thrust, which acts directly on the fixed supports of the pipeline system, placing a significant burden on the system's structural design. To balance this thrust, complex tie rod or hinge structures are typically required, but this limits their multidimensional compensation capabilities.

[0006] Split-type flexible joint with clamp: This type of joint typically consists of a split clamp, a sealing ring, and a sleeve. It has a simple structure and is easy to install. It can effectively absorb vibration and displacement in pipeline systems. However, its core sealing components are mostly made of polymer materials such as rubber, which significantly limits its pressure resistance, temperature resistance, and service life. Especially in high-temperature environments, the sealing material is prone to aging and failure, posing safety hazards.

[0007] To overcome the aforementioned shortcomings, some technical solutions attempt to combine bellows with universal hinge structures. For example, Chinese utility model patent CN203703441U discloses a bellows-type universal joint. This solution involves welding connecting pipes to both ends of the bellows, and connecting a hinge ring fixed on the connecting pipe to a universal ring via a pin, forming a universal joint to achieve angle compensation. Although this solution provides a solution approach, analysis reveals the following deficiencies:

[0008] Reliability issues: Its structural design is not strong enough to withstand complex vibration loads, making it prone to fatigue damage and resulting in poor reliability.

[0009] Insufficient compensation angle: The hinge ring and universal ring structure designed for this product still cannot achieve a large enough angle compensation range, which cannot meet the requirements of the new generation of aircraft piping systems for large-angle flexible connections.

[0010] In summary, when existing technologies are applied to large-diameter, high-pressure, and large-angle compensated aviation pipeline systems, they generally suffer from problems such as small compensation angle, weak pressure-bearing capacity, poor reliability, complex structure, or additional burden on the system, making it difficult to simultaneously meet the requirements of modern aviation equipment for high performance, miniaturization, and high reliability. Summary of the Invention

[0011] The purpose of this invention is to provide a spherical bellows type large-angle high-pressure universal joint to solve the problems of existing joints having small compensation angle, limited pressure resistance, poor vibration and fatigue reliability, and complex structure.

[0012] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0013] A spherical corrugated pipe type large-angle high-pressure universal joint includes a spherical corrugated pipe, with outer cylinders symmetrically sleeved at both ends of the outer side of the spherical corrugated pipe, and connecting rings provided on the outer cylinders. Welding rings are movably connected to both ends of the spherical corrugated pipe.

[0014] The connecting ring is rotatably connected to the two outer cylinders via a pin and is locked in place by connecting screws.

[0015] Furthermore, the outer cylinder has a cylindrical barrel structure, and the thickness of the part of the outer cylinder connected to the pin is greater than the thickness of other parts of the outer cylinder. The mating surface of the two outer cylinders has an "S" shaped fitting structure.

[0016] Furthermore, two mounting holes are provided at the protruding position of the "S"-shaped fitting structure on the outer cylinder mating surface. After the two outer cylinders are combined, the four mounting holes are located on the same plane.

[0017] Furthermore, the inner diameter of the spherical bellows is the same, while the outer diameter varies in a gradient.

[0018] Furthermore, an adjustable washer ring is provided between the connecting ring and the outer cylinder.

[0019] Furthermore, the connecting screw is threaded to the pin; the head of the connecting screw is provided with a wedge-shaped slope, which causes the tail of the pin to deform and expand during assembly, thereby fixing the pin to the outer cylinder.

[0020] Furthermore, the welding ring and the end of the spherical bellows are sealed together using resistance welding.

[0021] Furthermore, the material of the spherical corrugated pipe is austenitic stainless steel or high-temperature alloy.

[0022] The present invention has the following beneficial effects:

[0023] This invention combines a spherical bellows with an "S"-shaped fitted outer cylinder, achieving both large-angle compensation and high-pressure bearing capacity, thus overcoming the performance bottlenecks of existing technologies. Furthermore, the variable wall thickness design of the outer cylinder and the unique wedge-shaped screw locking pin structure significantly enhance the joint's vibration and fatigue resistance, improving the overall structural reliability. The application of an all-metal structure and high-temperature alloy materials, combined with welded seals, ensures excellent high-temperature resistance and sealing performance, reducing maintenance requirements. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of a spherical corrugated pipe type large-angle high-pressure universal joint according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the outer cylinder structure of a spherical corrugated pipe type large-angle high-pressure universal joint according to an embodiment of the present invention;

[0026] Figure 3 This is a cross-sectional schematic diagram of a spherical corrugated pipe type high-angle universal joint according to an embodiment of the present invention;

[0027] Figure 4 This is a cross-sectional view of the connecting ring of a spherical corrugated pipe type large-angle high-pressure universal joint according to an embodiment of the present invention;

[0028] Figure 5 for Figure 4 Enlarged structural diagram at point A in the middle.

[0029] Figures 1 to 5 The reference numerals in the attached drawings are respectively: 1-spherical bellows, 2-outer cylinder, 3-connecting ring, 4-welding ring, 5-connecting screw, 6-adjustable washer ring, 7-pin. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please refer to Figure 1 This embodiment provides a spherical bellows type large-angle high-pressure universal joint, which includes a spherical bellows 1. Two outer cylinders 2 are symmetrically fitted at both ends of the outer side of the spherical bellows 1. A connecting ring 3 is provided on the outside of the two outer cylinders 2 to connect the two outer cylinders 2 into a single universal hinge. Furthermore, welding rings 4 are movably connected to both ends of the spherical bellows 1 for docking with external pipes.

[0032] In this embodiment, the spherical bellows 1 is specially designed with a uniform inner diameter and a gradient outer diameter. This spherical design optimizes the stress distribution under pressure and bending moment, reduces local stress concentration, and thus enhances its high-pressure resistance, bending moment resistance, and instability resistance compared to traditional bellows. The material of the spherical bellows 1 is preferably austenitic stainless steel or a high-temperature alloy to meet the requirements of high-temperature operating conditions.

[0033] As attached Figure 2 As shown, the outer cylinder 2 is a cylindrical barrel structure. Its mating surface, i.e., the side where the two outer cylinders 2 approach each other, adopts an "S"-shaped fitting structure. This "S"-shaped design increases the relative rotation space between the two outer cylinders 2, thereby achieving a greater angle compensation capability. To further improve the vibration resistance and fatigue resistance of the joint, the outer cylinder 2 adopts a variable wall thickness design, that is, the part connected to the pin 7 is thicker than other parts. Mounting holes are respectively provided at the protruding positions of the "S"-shaped structure on the mating surface of the two outer cylinders 2. When the two outer cylinders 2 are combined, all mounting holes are located on the same plane, ensuring the smooth installation and precise alignment of the subsequent pin 7.

[0034] Details are as attached Figure 3-4 As shown, the connecting ring 3 is rotatably connected to the two outer cylinders 2 by four pins 7 and four connecting screws 5. To ensure smooth rotation and uniform radial clearance between the connecting ring 3 and the outer cylinder 2, an adjustable washer ring 6 is also provided between them.

[0035] As attached Figure 5As shown, the connecting screw 5 is threaded to the tail of the pin 7. The head of the connecting screw 5 has a wedge-shaped bevel. During assembly, when the connecting screw 5 is tightened, the wedge-shaped bevel at its head presses against the tail of the pin 7, causing it to deform and expand slightly, thereby firmly fixing the pin 7 to the mounting hole of the outer cylinder 2. This design not only ensures a reliable connection but also effectively eliminates the thrust generated by the pressure of the conduit system.

[0036] The assembly and specific working process of this invention are as follows:

[0037] The pin 7 is initially installed on the two outer cylinders 2, and then the two outer cylinders 2 are combined and fitted onto the outside of the spherical bellows 1. Next, an adjustable washer 6 is inserted into the pin 7, and a connecting ring 3 is fitted onto the outer cylinder 2, so that the hole of the connecting ring 3 is concentric with the hole of the outer cylinder 2. Subsequently, the connecting screw 5 is threaded onto the pin 7 and tightened, using the wedge-shaped slope principle described above to fix the entire universal hinge structure together.

[0038] After the universal hinge structure is assembled, the welding ring 4 is inserted into the inner hole of the end of the spherical bellows 1, with a small clearance fit between the two. Finally, the welding ring 4 and the end of the spherical bellows 1 are sealed together by resistance welding (e.g., resistance seam welding).

[0039] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A spherical corrugated pipe type large-angle high-pressure universal joint, characterized in that, It includes a spherical corrugated pipe (1), with an outer cylinder (2) symmetrically sleeved at both ends of the outer side of the spherical corrugated pipe (1), a connecting ring (3) provided on the outer cylinder (2), and welding rings (4) movably connected to both ends of the spherical corrugated pipe (1); The connecting ring (3) is rotatably connected to the two outer cylinders (2) by a pin (7) and locked by a connecting screw (5); the outer cylinder (2) is a cylindrical barrel structure, and the thickness of the part of the outer cylinder (2) connected to the pin (7) is greater than the thickness of other parts of the outer cylinder (2). The mating surface of the two outer cylinders (2) is an "S"-shaped fitting structure; two mounting holes are provided at the protruding position of the "S"-shaped fitting structure of the mating surface of the outer cylinder (2). After the two outer cylinders (2) are combined, the four mounting holes are located on the same plane; the inner diameter of the spherical corrugated pipe (1) is the same, and the outer diameter varies in a gradient; an adjustable washer ring (6) is provided between the connecting ring (3) and the outer cylinder (2); the connecting screw (5) is threadedly connected to the pin (7); the head of the connecting screw (5) is provided with a wedge-shaped slope. During assembly, the wedge-shaped slope causes the tail of the pin (7) to deform and expand, thereby fixing the pin (7) to the outer cylinder (2).

2. The spherical corrugated pipe type large-angle high-pressure universal joint according to claim 1, characterized in that, The welding ring (4) and the end of the spherical bellows (1) are sealed together by resistance welding.

3. The spherical corrugated pipe type large-angle high-pressure universal joint according to claim 1, characterized in that, The material of the spherical corrugated pipe (1) is austenitic stainless steel or high-temperature alloy.

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