Multi-layer corrugated pipe, vacuum arc-extinguishing chamber and vacuum circuit breaker

Abstract

The invention belongs to the field of corrugated pipes, and discloses a multi-layer corrugated pipe, a vacuum arc extinguish chamber and a vacuum circuit breaker.The multi-layer corrugated pipe comprises a multi-layer corrugated pipe body, a first connecting flange and a second connecting flange, one end of the first connecting flange is welded to the multi-layer corrugated pipe body in an argon arc welding mode, and the other end of the first connecting flange is welded to the multi-layer corrugated pipe body in an argon arc welding mode; the other end is in brazed connection with a movable conducting rod of the vacuum arc-extinguishing chamber; one end of the second connecting method is welded with the multi-layer corrugated pipe body in an argon arc welding manner, and the other end of the second connecting method is brazed with a movable end cover plate of the vacuum arc-extinguishing chamber, so that the multi-layer corrugated pipe is uniformly stressed in a long-stroke movement process, and a local stress concentration phenomenon caused by asymmetric assembly is effectively inhibited; the problem that the mechanical life of the vacuum arc-extinguishing chamber is shortened due to poor welding of the multi-layer corrugated pipe body is solved, a gap is reserved between the lower end face of the fourth connecting piece and the multi-layer corrugated pipe body, direct contact between the first connecting flange and the first wave of the multi-layer corrugated pipe body is avoided, and the mechanical life of the multi-layer corrugated pipe is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of bellows and relates to a multi-layer bellows, a vacuum interrupter and a vacuum circuit breaker. Background Art

[0002] As power systems rapidly evolve toward higher voltages, larger capacities, and smarter systems, high-voltage switchgear is placing increasingly stringent performance demands on vacuum interrupters. As key components for rapid circuit interruption and reliable isolation, vacuum interrupters must maintain stable insulation and arc-extinguishing capabilities under high voltages, high currents, long travel distances, and complex operating conditions. However, in high-voltage, high-current applications, traditional single-layer bellows structures, due to limitations in the material's mechanical and geometric properties, struggle to meet the technical requirements of these new vacuum interrupters.

[0003] Due to the increased contact spacing, complex electric field distribution, and long-stroke motion requirements of high-voltage, high-current vacuum interrupters, bellows must maintain high vacuum tightness while also possessing enhanced axial stiffness, fatigue resistance, and structural stability. Single-layer bellows are susceptible to buckling instability or elastic failure due to the repeated deformation and stress concentration caused by long-stroke motion in high-pressure gas environments, such as high-pressure sealing tests or operating conditions with complex pressure fluctuations. This degrades the vacuum chamber's sealing performance, leading to the risk of air leakage in the interrupter, which directly shortens its mechanical life and electrical reliability.

[0004] To address the above issues, a multi-layer bellows structure is used instead of a single-layer design. Multi-layer bellows enhance radial stiffness and axial load-bearing capacity through a laminated structure, and utilize an interlayer stress dispersion mechanism to enhance fatigue resistance, significantly improving the mechanical stability of high-voltage, high-current vacuum interrupters under long-stroke conditions. However, due to the increased number of layers, complex structure, and differences in material thickness, the welding process of multi-layer bellows faces new challenges: if the process parameters of traditional welding methods for single-layer bellows, such as laser welding, electron beam welding, or vacuum brazing, are used, microscopic defects in the weld seam can easily occur due to uneven heat input, poor interlayer fusion, or residual stress concentration, leading to seal failure or shortened mechanical life. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a multi-layer bellows, a vacuum arc chamber and a vacuum circuit breaker, wherein a first connecting flange and a second connecting flange are installed at both ends of the multi-layer bellows body, one end of the first connecting flange is fixedly connected to the multi-layer bellows body by argon arc welding, and the other end is fixedly connected to the moving conductive rod of the vacuum arc chamber by brazing, one end of the second connecting flange is fixedly connected to the multi-layer bellows body by argon arc welding, and the other end is fixedly connected to the moving end cover of the vacuum arc chamber by brazing, so as to avoid the problem of air leakage or reduced mechanical life due to unreliable connection quality at both ends of the multi-layer bellows.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a multi-layer bellows, comprising a multi-layer bellows body, a first connecting flange and a second connecting flange; protrusions are provided at both axial ends of the multi-layer bellows body; the first connecting flange is provided at one end of the multi-layer bellows body, one end of the first connecting flange is fixedly connected to the multi-layer bellows body, and the other end is used to be fixedly connected to the moving conductive rod of the vacuum arc chamber; the second connecting flange is provided at the other end of the multi-layer bellows body, one end of the second connecting flange is fixedly connected to the multi-layer bellows body, and the other end is used to be fixedly connected to the moving end cover plate of the vacuum arc chamber; the first connecting flange and the second connecting flange are hollow structures.

[0007] Furthermore, the first connecting flange includes a first connecting member, a second connecting member, a third connecting member and a fourth connecting member arranged in sequence from the inside to the outside, the inner ring of the first connecting member is sleeved on the outer ring of the multi-layer corrugated pipe body, the first connecting member, the second connecting member, the third connecting member and the fourth connecting member are an integral structure, and the lower end surfaces of the first connecting member, the second connecting member, the third connecting member and the fourth connecting member are located on the same horizontal line.

[0008] Furthermore, the thickness of the first connecting member is 0.3-3 mm, the thickness of the second connecting member is 1-20 mm, and the thickness of the fourth connecting member is 2-10 mm.

[0009] Furthermore, the distance between the upper end surface of the first connecting member and the upper end surface of the second connecting member is 1-5mm; the distance between the upper end surface of the first connecting member and the upper end surface of the third connecting member is 1-4mm; the distance between the upper end surface of the third connecting member and the upper end surface of the fourth connecting member is 0.8-5mm.

[0010] Furthermore, the gap between the lower end surface of the fourth connecting member and the multi-layer corrugated pipe body is 0.5-5 mm.

[0011] Furthermore, the second connecting flange includes a fifth connecting member, a sixth connecting member, a seventh connecting member and an eighth connecting member arranged in sequence from the inside to the outside, the inner ring of the fifth connecting member is sleeved on the outer ring of the multi-layer corrugated pipe body, the fifth connecting member, the sixth connecting member, the seventh connecting member and the eighth connecting member are an integral structure, and the lower end surfaces of the fifth connecting member, the sixth connecting member, the seventh connecting member and the eighth connecting member are located on the same horizontal line.

[0012] Furthermore, the first connecting flange and the second connecting flange have the same structural dimensions.

[0013] Furthermore, the first connecting flange and the second connecting flange are made of stainless steel.

[0014] The present invention also provides a vacuum interrupter, comprising a shell, a movable conductive rod movably mounted on the shell, and a multi-layer bellows fixed on the movable conductive rod; the multi-layer bellows is the multi-layer bellows mentioned above.

[0015] The present invention also provides a vacuum circuit breaker, comprising a vacuum interrupter and an operating mechanism; the vacuum interrupter comprises an outer shell, a movable conductive rod movably mounted on the outer shell, and a multi-layer bellows fixed on the movable conductive rod; the operating mechanism is transmission-connected to the movable conductive rod; the multi-layer bellows is the above-mentioned multi-layer bellows.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a multi-layer bellows, wherein a first connecting flange and a second connecting flange are symmetrically arranged at both ends of the multi-layer bellows body, one end of the first connecting flange is welded to the multi-layer bellows body by argon arc welding, and the other end is brazed to the movable conductive rod of the vacuum arc chamber; one end of the second connecting flange is welded to the multi-layer bellows body by argon arc welding, and the other end is brazed to the movable end cover plate of the vacuum arc chamber, thereby reliably connecting the multi-layer bellows to the vacuum arc chamber, which not only simplifies the complexity of the manufacturing process, but also ensures that the multi-layer bellows is subjected to uniform force during long-stroke movement, effectively suppresses the local stress concentration phenomenon caused by asymmetric assembly, and avoids the problem of reduced mechanical life of the vacuum arc chamber due to poor welding of the multi-layer bellows body.

[0017] The present invention provides a multi-layer corrugated pipe, wherein the first connecting flange and the second connecting flange have the same structural dimensions, the first connecting flange includes a first connecting piece, a second connecting piece, a third connecting piece and a fourth connecting piece; the second connecting flange includes a fifth connecting piece, a sixth connecting piece, a seventh connecting piece and an eighth connecting piece; the lower end surfaces of the first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece are located on the same horizontal line, and the gap between the lower end surface of the fourth connecting piece and the multi-layer corrugated pipe body is 0.5-5mm, thereby avoiding direct contact between the first connecting flange and the first wave of the multi-layer corrugated pipe body, ensuring that the multi-layer corrugated pipe body and the first connecting flange are connected only by a protrusion, which is beneficial to improving the mechanical life of the multi-layer corrugated pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a cross-sectional view of a multi-layer corrugated pipe according to the present invention.

[0019] Reference numerals: 1-Multi-layer corrugated pipe body; 2-First connecting flange; 3-Second connecting flange. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0021] Example 1 The present invention provides a multi-layer bellows, comprising a multi-layer bellows body 1, a first connecting flange 2 and a second connecting flange 3; protrusions are provided at both axial ends of the multi-layer bellows body 1; the first connecting flange 2 is provided at one end of the multi-layer bellows body 1, one end of the first connecting flange 2 is fixedly connected to the multi-layer bellows body 1, and the other end is used to be fixedly connected to the moving conductive rod of the vacuum interrupter; the second connecting flange 3 is provided at the other end of the multi-layer bellows body 1, one end of the second connecting flange 3 is fixedly connected to the multi-layer bellows body 1, and the other end is used to be fixedly connected to the moving end cover of the vacuum interrupter; the first connecting flange 2 and the second connecting flange 3 are hollow structures.

[0022] like Figure 1 As shown, the multilayer bellows body 1 is welded to the vacuum interrupter by installing a first connecting flange 2 and a second connecting flange 3 at each end of the multilayer bellows body 1. The first connecting flange 2 and the second connecting flange 3 utilize identical structural dimensions and are symmetrically arranged at the axial ends of the multilayer bellows body 1. This not only simplifies the complexity of the manufacturing process but also ensures uniform force distribution during long-stroke movement of the multilayer bellows. This effectively suppresses local stress concentration caused by asymmetric assembly and avoids the reduction in the mechanical life of the vacuum interrupter due to poor welding of the multilayer bellows body.

[0023] Specifically, the first connecting flange 2 and the second connecting flange 3 have the same structure, with the shorter end being the upper end and the longer end being the lower end. The lower end of the first connecting flange 2 is welded to the end of the multi-layer bellows body 1 via argon arc welding, and the other end is brazed to the movable conductive rod of the vacuum interrupter. The second connecting flange 3 is provided at the other end of the multi-layer bellows body 1. The lower end of the second connecting flange 3 is welded to the rear end of the multi-layer bellows body 1 via argon arc welding, and the other end is brazed to the movable end cover of the vacuum interrupter, thereby reliably connecting the multi-layer bellows body 1 to the vacuum interrupter.

[0024] The bellows body 1 is configured as a multi-layer structure, which is beneficial to improving the overall toughness of the bellows body 1, thereby improving the fatigue strength of the bellows body 1, and is beneficial to extending the service life of the bellows body.

[0025] TIG welding uses an inert gas, such as argon, as a shielding agent, effectively isolating the weld pool from contamination by reactive gases like oxygen and nitrogen in the air. This prevents defects like porosity and slag inclusions in the weld seam when welding easily oxidized materials like stainless steel and nickel-based alloys, significantly improving weld density and airtightness, meeting the stringent high-vacuum sealing requirements of vacuum interrupters.

[0026] TIG welding precisely controls heat input by adjusting current, voltage, and welding speed, thereby minimizing the heat-affected zone (HAZ). For multi-layer bellows structures, low heat input effectively suppresses interlayer deformation, warping, or grain coarsening caused by overheating, thus avoiding the loss of mechanical strength caused by thermal stress concentration.

[0027] Brazing achieves this by melting and wetting the surface of the base metal with a filler metal, such as a brazing filler metal. During the brazing process, the base metal remains unchanged; only the filler metal, such as a silver-, copper-, or nickel-based alloy, melts at a temperature below the base metal's melting point. This significantly reduces heat input, preventing grain coarsening, deformation, or mechanical property degradation in the multi-layer bellows, first connecting flange, or second connecting flange caused by high temperatures.

[0028] Brazing uses capillary action to evenly fill the gaps between joints with liquid filler metal, forming a smooth, continuous interface. Compared to the raised seams of fusion welding, brazed joints lack significant geometric changes, effectively reducing stress concentration, improving fatigue resistance, and extending mechanical life.

[0029] Both axial ends of the multi-layer corrugated pipe body 1 are provided with protrusions, the outer diameters of which match the inner diameters of the first connecting flange 2 and the second connecting flange 3. In this embodiment, the inner diameters of the first connecting flange 2 and the second connecting flange 3 are 60-150 mm.

[0030] The first connecting flange 2 includes, from the inside out, a first connecting member, a second connecting member, a third connecting member, and a fourth connecting member. These members are integrally structured and fixed to the end of the multi-layer bellows body 1. It should be noted that the lower ends of the first, second, third, and fourth connecting members are located on the same horizontal line. This ensures that there is no tilting moment between the flange and the arc-extinguishing chamber housing during installation to avoid local seal failure.

[0031] The thickness of the first connecting member is 0.3-3 mm, that is, Figure 1The "A" in the figure covers the full range of vacuum interrupter requirements from 12-145kV, eliminating the need to develop specialized connectors for different voltage levels and reducing tooling costs. When the thickness of the first connector is 0.3-1mm, TIG welding can utilize a precision welding mode with a low current of 20-80A and a short arc length of 1-2mm to achieve controlled penetration and avoid burn-through of the base material or thermal deformation between layers of the bellows caused by excessive heat input. For first connectors 1-3mm thick, TIG welding in pulsed mode with a peak current of 100-150A and a base current of 30-50A can enhance the tensile strength of the joint.

[0032] The thickness of the second connecting member is 1-20 mm, that is, Figure 1 The B in the figure can significantly reduce the risk of deformation caused by thermal stress during argon arc welding, ensure the sealing and conductivity of the brazing interface, and improve the consistency of the overall electrical performance of the arc extinguishing chamber. In addition, the 1-20mm thick second connector covers a variety of needs from lightweight support structures to heavy conductive components, and the thickness can be flexibly selected according to the power level of the arc extinguishing chamber. For example, a thin specification of 1-5mm can be used to achieve a lightweight design in low-voltage scenarios, while a thick specification of 10-20mm can be used in high-voltage scenarios to enhance the conductive cross-section and mechanical strength, taking into account performance optimization and material cost balance under different working conditions.

[0033] The thickness of the third connecting member is Figure 1 The thickness of C is not limited and can be adjusted accordingly according to actual conditions.

[0034] The thickness of the fourth connecting member is 2-10 mm, that is, Figure 1 The D in the figure not only enables high-precision positioning surface machining through mechanical processes such as milling and grinding, but also avoids deformation during clamping due to excessive thinness (thickness <2mm) or redundant positioning structures due to excessive thickness (thickness >10mm). Using 10mm thick connectors in 110-145kV arc extinguishing chambers allows for further improvement in joint sealing through multi-layer brazing processes, such as stacking 2-3 layers of brazing filler metal. Combined with helium mass spectrometry leak detection, this meets the stringent requirements of UHV equipment. Using 2-5mm thick connectors in 12-35kV arc extinguishing chambers allows for weight reduction by 20%-30% through hollowing-out designs, such as grid-like structures, while maintaining structural strength in the brazing area.

[0035] The distance between the upper end surface of the first connecting member and the upper end surface of the second connecting member is 1-5 mm, that is, Figure 1 The H in the figure uses a precision welding mode with a low current of 20-80A and a short arc length of 1-2mm to achieve precise penetration control within a gap of 1-5mm, avoiding burning through thin materials or damaging the interlayer structure of the bellows. It uses a pulsed argon arc welding peak current of 100-150A and a base current of 30-50A to improve the stability of the molten pool within a gap of 1-5mm, ensuring the tensile strength of the joint and welding efficiency.

[0036] The distance between the upper end surface of the first connecting member and the upper end surface of the third connecting member is 1-4 mm, that is, Figure 1 In J, the first connector with a thickness of 0.3-3mm is sensitive to heat and requires rapid heat dissipation; the third connector has no limit on thickness and can be used as a heat dissipation carrier. In summary, the 1-4mm gap forms a thermal buffer zone through physical isolation, reducing the direct thermal impact of the argon arc welding heat source on the brazing area.

[0037] The distance between the upper end surface of the third connecting member and the upper end surface of the fourth connecting member is 0.8-5mm, that is, Figure 1 The K in the brazing process and the 0.8-5mm gap can form a thermal stress buffer zone, reducing the interface cracks caused by thermal shrinkage differences during the brazing cooling process.

[0038] The lower end surfaces of the first, second, third, and fourth connectors are located on the same horizontal line. The gap between the lower end surface of the fourth connector and the multi-layer bellows body 1 is 0.5-5mm, preventing direct contact between the first connecting flange 1 and the first wave of the multi-layer bellows body 1. This ensures that the multi-layer bellows body 1 and the first connecting flange are connected only by a protrusion, which is beneficial for improving the mechanical life of the multi-layer bellows. If the gap between the lower end surface of the fourth connector and the multi-layer bellows body 1 is less than 0.5mm, direct contact between the first wave of the multi-layer bellows body 1 and the first connecting flange 1 will cause micro-wear during mechanical vibration or opening and closing operations, resulting in thinning of the multi-layer bellows wall thickness or even cracking.

[0039] The second connecting flange 3 has the same structural dimensions as the first connecting flange 2 , except that the first connecting flange 2 is installed at the end of the multi-layer corrugated pipe body 1 , and the second connecting flange 3 is installed at the tail of the multi-layer corrugated pipe body 1 .

[0040] The second connecting flange 3 includes a fifth connecting member, a sixth connecting member, a seventh connecting member and an eighth connecting member arranged in sequence from the inside to the outside, the inner ring of the fifth connecting member is sleeved on the outer ring of the multi-layer corrugated pipe body 1, the fifth connecting member, the sixth connecting member, the seventh connecting member and the eighth connecting member are an integral structure, and the lower end surfaces of the fifth connecting member, the sixth connecting member, the seventh connecting member and the eighth connecting member are located on the same horizontal line.

[0041] The fifth connecting member corresponds to the first connecting member, the sixth connecting member corresponds to the second connecting member, the seventh connecting member corresponds to the third connecting member, and the eighth connecting member corresponds to the fourth connecting member.

[0042] The first connecting flange 2 and the second connecting flange 3 are made of stainless steel, specifically, 022Cr17Ni12Mo2 (316L) or 06Cr19Ni10 (304) stainless steel.

[0043] In summary, the present invention provides a multilayer bellows, which achieves high-reliability welding by installing a first connecting flange 2 and a second connecting flange 3 at each end of the multilayer bellows. This structure creates a dual-rigidity transition weld structure. This significantly improves the weld's airtightness and mechanical load-bearing capacity, effectively avoiding the degradation of the arc extinguishing chamber's mechanical life due to bellows deformation mismatch and weld metallurgical defects in traditional welding processes. The axial impact stress generated by the arc extinguishing chamber's opening and closing operation is dispersed from the thin-walled region of the multilayer bellows body 1 to the thick-walled regions of the first connecting flange 2 and the second connecting flange 3, reducing residual stress in the weld and suppressing stress corrosion cracking.

[0044] Example 2 The present invention also provides a vacuum arc chamber, comprising an outer shell, a movable conductive rod movably mounted on the outer shell, and a multi-layer bellows fixed on the movable conductive rod; the multi-layer bellows comprises a multi-layer bellows body 1, a first connecting flange 2 and a second connecting flange 3; protrusions are provided at both axial ends of the multi-layer bellows body 1; the first connecting flange 2 is arranged at one end of the multi-layer bellows body 1, one end of the first connecting flange 2 is fixedly connected to the multi-layer bellows body 1, and the other end is used to be fixedly connected to the movable conductive rod of the vacuum arc chamber; the second connecting flange 3 is arranged at the other end of the multi-layer bellows body 1, one end of the second connecting flange 3 is fixedly connected to the multi-layer bellows body 1, and the other end is used to be fixedly connected to the movable end cover of the vacuum arc chamber; the first connecting flange 2 and the second connecting flange 3 are hollow structures.

[0045] Example 3 The present invention also provides a vacuum circuit breaker, comprising a vacuum interrupter and an operating mechanism; the vacuum interrupter comprises a housing, a movable conductive rod movably mounted on the housing, a multi-layer bellows fixed on the movable conductive rod, and the operating mechanism is transmission-connected to the movable conductive rod. The multi-layer bellows comprises a multi-layer bellows body 1, a first connecting flange 2, and a second connecting flange 3; protrusions are provided at both axial ends of the multi-layer bellows body 1; the first connecting flange 2 is provided at one end of the multi-layer bellows body 1, one end of the first connecting flange 2 is fixedly connected to the multi-layer bellows body 1, and the other end is used to be fixedly connected to the movable conductive rod of the vacuum interrupter; the second connecting flange 3 is provided at the other end of the multi-layer bellows body 1, one end of the second connecting flange 3 is fixedly connected to the multi-layer bellows body 1, and the other end is used to be fixedly connected to the movable end cover of the vacuum interrupter; the first connecting flange 2 and the second connecting flange 3 are hollow structures.

[0046] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

Claims

1. A multi-layer corrugated pipe, characterized in that: It comprises a multi-layer bellows body (1), a first connecting flange (2) and a second connecting flange (3); The multi-layer bellows body (1) is provided with protrusions at both axial ends; the first connecting flange (2) is provided at one end of the multi-layer bellows body (1), one end of the first connecting flange (2) is fixedly connected to the multi-layer bellows body (1), and the other end is used for fixedly connecting to the movable conductive rod of the vacuum interrupter; the second connecting flange (3) is provided at the other end of the multi-layer bellows body (1), one end of the second connecting flange (3) is fixedly connected to the multi-layer bellows body (1), and the other end is used for fixedly connecting to the movable end cover of the vacuum interrupter; the first connecting flange (2) and the second connecting flange (3) are hollow structures.

2. The multi-layer corrugated tube according to claim 1, characterized in that: The first connecting flange (2) includes a first connecting member, a second connecting member, a third connecting member and a fourth connecting member arranged in sequence from the inside to the outside, the inner ring of the first connecting member is sleeved on the outer ring of the multi-layer corrugated pipe body (1), the first connecting member, the second connecting member, the third connecting member and the fourth connecting member are an integrated structure, and the lower end surfaces of the first connecting member, the second connecting member, the third connecting member and the fourth connecting member are located on the same horizontal line.

3. The multi-layer corrugated tube according to claim 2, characterized in that: The thickness of the first connecting member is 0.3-3 mm, the thickness of the second connecting member is 1-20 mm, and the thickness of the fourth connecting member is 2-10 mm.

4. The multi-layer corrugated tube according to claim 2, characterized in that: The distance between the upper end surface of the first connecting member and the upper end surface of the second connecting member is 1-5 mm; The distance between the upper end surface of the first connecting member and the upper end surface of the third connecting member is 1-4 mm; The distance between the upper end surface of the third connecting member and the upper end surface of the fourth connecting member is 0.8-5 mm.

5. The multi-layer corrugated tube according to claim 2, characterized in that: The gap between the lower end surface of the fourth connecting piece and the multi-layer corrugated pipe body (1) is 0.5-5 mm.

6. The multi-layer corrugated tube according to claim 2, characterized in that: The second connecting flange (3) includes a fifth connecting member, a sixth connecting member, a seventh connecting member and an eighth connecting member arranged in sequence from the inside to the outside, the inner ring of the fifth connecting member is sleeved on the outer ring of the multi-layer corrugated pipe body (1), the fifth connecting member, the sixth connecting member, the seventh connecting member and the eighth connecting member are an integrated structure, and the lower end surfaces of the fifth connecting member, the sixth connecting member, the seventh connecting member and the eighth connecting member are located on the same horizontal line.

7. The multi-layer corrugated tube according to claim 6, characterized in that: The first connecting flange (2) and the second connecting flange (3) have the same structural dimensions.

8. The multi-layer corrugated tube according to claim 7, characterized in that: The first connecting flange (2) and the second connecting flange (3) are made of stainless steel.

9. A vacuum interrupter, characterized in that: The invention comprises a shell, a movable conductive rod movably mounted on the shell, and a multi-layer corrugated tube fixed on the movable conductive rod; the multi-layer corrugated tube is the multi-layer corrugated tube according to any one of claims 1 to 8.

10. A vacuum circuit breaker, characterized in that: It comprises a vacuum interrupter and an operating mechanism; the vacuum interrupter comprises an outer shell, a movable conductive rod movably mounted on the outer shell, a multi-layer bellows fixed on the movable conductive rod, and the operating mechanism is transmission-connected to the movable conductive rod; the multi-layer bellows is the multi-layer bellows described in any one of claims 1-8.

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