Contact structure with active vacuum arc dispersing function based on inner phase change driving

Abstract

The application discloses a contact structure with active vacuum arc dispersing function based on internal phase change driving, which comprises a static side contact piece, a static side conductive rod fixedly connected with the static side contact piece, a dynamic side contact piece oppositely arranged with the static side contact piece, and a dynamic side conductive rod fixedly connected with the dynamic side contact piece, wherein arc dispersing devices are arranged in the static side contact piece and the dynamic side contact piece, and the two arc dispersing devices are symmetrically arranged with the radial center line of the contact structure as the symmetric axis. The arc dispersing device is a hollow sealing structure, the side close to the contact surface is a flexible metal diaphragm, the inside is filled with liquid low-boiling point working medium, and the bottom is provided with a capillary core structure made of porous sintered material. The contact structure can drive the phase change of the built-in working medium by the energy of the arc itself, generate transient mechanical pulse to make the arc root continuously move on the anode surface, thereby destroy the stable heat conduction of the arc to the local anode, inhibit the anode ablation from the source, and improve the anti-ablation ability and service life of the vacuum switch.

Description

Technical Field

[0001] This invention belongs to the field of vacuum switch technology, specifically relating to a contact structure with active vacuum arc dissipation function based on internal phase change drive. Background Technology

[0002] In a vacuum switch, the vacuum arc contracts as it moves from the cathode to the anode. When the breaking current exceeds a certain critical value, the arc plasma flow in the arc column region cannot uniformly cover the anode surface. The arc root on the anode surface contracts into one or several tiny regions under the influence of electromagnetic and thermal fields. At this point, these regions experience extremely high energy injection, with a power density reaching 10^6 kilometres per second. 8 -10 10 W / m². Under this energy, the anode surface temperature rises rapidly and exceeds the material's melting point, causing the anode to melt. When the energy is high enough, the anode temperature even approaches or reaches its boiling point, accompanied by droplet splashing and violent vaporization. The splashed metal droplets leave ablation pits in the center of the contact, while the ejected material condenses around the pits, forming a porous and loose molten layer structure. This violent phase transition process directly leads to two serious consequences: firstly, a net loss of contact material, manifested as the deepening and expansion of the ablation pits, which directly shortens the electrical life of the contact; secondly, deterioration of the contact surface morphology and composition, with slag and splashes making the surface rough and uneven, reducing insulation recovery strength, and potentially causing insulation degradation or re-breakdown after repeated operations.

[0003] To address the long-standing technical challenge of anodic ablation, researchers have explored various technical approaches. Among them, contact material optimization is a fundamental and widely used solution. Currently, copper-chromium composite materials are commonly used. In this system, the copper matrix ensures excellent conductivity of the contact, while chromium particles significantly improve the contact's resistance to arc erosion. However, the performance improvement potential of this material system is limited. More importantly, material optimization is essentially a passive protection method. It increases the material's tolerance threshold but cannot change the fundamental mode of concentrated arc energy injection. When faced with higher breaking capacity requirements or frequent operation, the ablation phenomenon of CuCr contacts is still unavoidable.

[0004] Another important technical approach is magnetic field control. Its principle is to apply an external or self-generated magnetic field to cause the arc root to rotate at high speed on the contact surface, thereby dispersing energy over a larger area. Specifically, the transverse magnetic field generates tangential electromagnetic force through a specially grooved contact structure, driving the arc along the surface; the longitudinal magnetic field, generated by a coil structure or special contact arm, is parallel to the arc axis to confine the plasma and maintain its diffusion pattern. Although magnetic field control technology has good diffusion effects, arc contraction is still difficult to avoid during high-capacity breaking. Furthermore, its system structure is relatively complex, requiring high design and manufacturing precision. In particular, longitudinal magnetic field contacts typically involve multi-component assembly, which not only increases manufacturing costs but also introduces potential mechanical reliability risks.

[0005] In summary, existing technologies share common shortcomings: they either passively improve the tolerance of the anode material or attempt to disperse energy but are structurally complex and have limited effectiveness. Currently, there is a lack of a fundamental solution that can actively and directly disrupt the stable energy transfer of the arc spot to the anode, and is structurally simple, requires no external source, and can adapt to the arc energy. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and propose a contact structure with active vacuum arc dissipation function based on internal phase change drive. The internal working fluid phase change is driven by the energy of the arc itself, generating transient mechanical pulses that cause the arc root to move continuously on the anode surface, thereby disrupting the stable heat conduction of the arc to the anode, inhibiting anode ablation from the source, and improving the ablation resistance and service life of the vacuum switch.

[0007] The technical solution adopted in this invention is a contact structure with active vacuum arc dispersing function based on internal phase change drive, including a stationary contact plate, a stationary conductive rod fixedly connected to the stationary contact plate, a moving contact plate opposite to the stationary contact plate, and a moving conductive rod fixedly connected to the moving contact plate. An arc dispersing device is provided inside both the stationary contact plate and the moving contact plate, and the two arc dispersing devices are symmetrically arranged with the radial center line of the contact structure as the axis of symmetry.

[0008] The invention is further characterized by:

[0009] The arc dispersing device is a hollow sealed structure, which is located close to the working surface of the contact, with the surface 0.8–1.2 mm away from the working surface of the contact.

[0010] The arc dispersing device has a flexible metal diaphragm near the contact surface, which is filled with a liquid low-boiling-point working fluid, and a capillary wick structure made of porous sintered material at the bottom.

[0011] The boiling point of the low-boiling working fluid is lower than the melting point of the anode substrate material, and is between 800K and 1600K, and its physicochemical properties are stable.

[0012] The filling volume of the low-boiling-point working fluid is 25%-35% of the effective volume of the cavity.

[0013] The flexible metal diaphragm has a thickness of 0.4-0.5 mm and is made of beryllium copper alloy, Hastelloy, special stainless steel or titanium alloy with an elastic modulus of 100-200 GPa and fatigue strength >300 MPa.

[0014] The capillary core structure is made of sintered copper powder, sintered stainless steel powder, metal foam or microporous ceramic material, with a porosity of 45%-55%.

[0015] The specific preparation method of the arc dispersal device is as follows:

[0016] Cavities are machined inside the stationary and moving contact plates. A capillary wick structure is placed at the bottom of the cavity. A low-boiling-point working fluid is injected into the cavity through a precision liquid injection system, and the injection volume is controlled to be 25%–35% of the effective volume of the cavity. The periphery of the flexible metal diaphragm is welded to the inner wall of the cavity through vacuum brazing, electron beam welding or laser welding.

[0017] The beneficial effects of this invention are:

[0018] (1) The method of the present invention differs from the passive material tolerance and magnetic field controlled arc mode. It sets up a built-in arc dispersing device in the contact structure, uses the energy of the arc itself to drive the phase change of the low boiling point working fluid, generates transient mechanical pulses, causes deformation of the contact center, and thus makes the arc root move uniformly on the anode surface, directly destroying the stable heat conduction between the arc and the anode, avoiding local overheating, and taking preventive intervention from the source of ablation, significantly reducing the anode ablation phenomenon, avoiding serious damage such as melting, splashing and vaporization of the anode surface material, thereby improving the switch's ablation resistance and service life;

[0019] (2) This invention uses mature processes such as vacuum brazing to construct a closed system. The working fluid (such as gallium indium tin alloy) is condensed and refluxed through a capillary structure and reused repeatedly. It is lossless and has stable physical and chemical properties, ensuring long-term reliable operation. In addition, the arc dissipation device is integrated inside the contact, which does not require additional increase in the overall volume of the switch. The core components (flexible metal diaphragm, capillary structure, sealed cavity) all use mature materials and processes in the current industrial field (such as CuCr contact substrate, vacuum brazing). The design and manufacturing costs are controllable, the mechanical reliability and engineering feasibility are high, and there is no additional assembly risk.

[0020] (3) The contact structure of the present invention does not require external energy or complex control components. It relies entirely on the energy of the electric arc itself and its own structure to complete the adaptive cycle of "heat absorption - working fluid phase change - surface vibration - system reset". It has a fast response speed (millisecond-level triggering) and is adapted to the dynamic evolution characteristics of the electric arc.

[0021] (4) Simulation and theoretical calculation verification show that under a 20kA breaking current condition, the anode ablation depth can be reduced from 150μm to 20μm, significantly reducing the net loss of contact material and extending the electrical life of the contacts. In addition, the contact structure of this invention also avoids the problems of rough contact surface and large damage to the molten pool morphology caused by arc ablation of traditional contacts, maintains the flatness of the anode working surface, reduces the risk of insulation deterioration or re-breakdown after multiple operations, and improves the breaking success rate of vacuum circuit breakers. Furthermore, for scenarios with higher breaking capacity requirements or frequent operation, compared with the defects of traditional CuCr contacts that are still prone to ablation, this structure effectively adapts to harsh working conditions through an active intervention mechanism, expanding the application range of vacuum switches. Attached Figure Description

[0022] Figure 1 This is an axial sectional view of the contact structure of the present invention;

[0023] Figure 2 This is an axial sectional view of the arc dispersing device in the contact structure of the present invention;

[0024] Figure 3 This is a schematic diagram illustrating the working principle of the arc dispersing device in the contact structure of the present invention. Figure 1 ;

[0025] Figure 4 This is a schematic diagram illustrating the working principle of the arc dispersing device in the contact structure of the present invention. Figure 2 ;

[0026] Figure 5 A curve showing the temperature comparison of the vacuum contact anode center before and after the arc dispersal device is installed. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] Example 1:

[0029] This invention is based on a contact structure with active vacuum arc dissipation function driven by internal phase change, such as... Figure 1 As shown, it includes a stationary contact piece, a stationary conductive rod fixedly connected to the stationary contact piece, a moving contact piece disposed opposite to the stationary contact piece, and a moving conductive rod fixedly connected to the moving contact piece. An arc dispersing device is provided inside both the stationary and moving contact pieces. The arc dispersing devices are disposed close to the working surface of the contact, and the two arc dispersing devices are symmetrically arranged with the radial center line of the contact structure as the axis of symmetry.

[0030] like Figure 2 As shown, the arc dispersing device is a hollow, sealed cuboid structure, but it can also be cylindrical or other structures. It is located directly below the working surface of the contact, with its upper surface 0.8–1.2 mm below the working surface. The side of the arc dispersing device closest to the contact surface is a flexible metal diaphragm filled with a liquid low-boiling-point working fluid, and its bottom has a capillary wick structure made of porous sintered material. (See diagram below.) Figure 3 and Figure 4 As shown, when a vacuum circuit breaker interrupts a large current, the low-boiling-point working fluid is heated to a superheated state and vaporized under the action of high-density heat flux, forming a pulsed vapor pressure in the sealed cavity. This drives the flexible metal diaphragm to produce a rapid, slight upward deformation, transmitting transient mechanical pulses to the contact working surface. This "jump" action breaks the thermal-electrical balance at the arc root and forces the arc root to shift, thereby changing the stable heat conduction of the arc to the anode. Before severe ablation of the anode material occurs, it actively disperses potential concentrated ablation points, thus inhibiting severe local ablation of the anode. In addition, the capillary wick structure achieves rapid and efficient reflux of the condensed liquid working fluid to the area below the diaphragm through capillary action.

[0031] The boiling point of the low-boiling-point working fluid should be lower than the melting point of the anode matrix material to ensure timely phase change during arc heating. This invention uses a liquid gallium-indium-tin alloy with a boiling point of 1573K, but other working fluids with boiling points between 800K and 1600K can also be used. The working fluid should maintain stable physicochemical properties during cyclic use, meaning it should not easily burn or explode at high temperatures and should not chemically react with the matrix material, ensuring long-term reliable operation of the contact structure. The filling volume of the low-boiling-point working fluid is 25%-35% of the effective cavity volume to ensure that the phase change energy conversion efficiency matches the arc heating process.

[0032] The arc dispersal device has a sealed environment inside, ensuring that the low-boiling-point working fluid inside follows the law of conservation of mass throughout its entire life cycle and does not suffer loss, thereby achieving repeatable and sustainable recycling.

[0033] The thickness of the flexible metal diaphragm is 0.4-0.5 mm. Furthermore, to ensure that the diaphragm's protruding displacement can deform the anode contact surface to move the arc root without damaging the device due to excessive deformation, the mechanical properties are limited: the elastic modulus is controlled between 100-200 GPa, and the fatigue strength is higher than 300 MPa. The material used to prepare the flexible metal diaphragm can be beryllium copper alloy, Hastelloy, special stainless steel, or titanium alloy, all within this performance range. The diaphragm structure is not limited to a flat surface shape; it can be designed as a pre-stressed corrugated or dish-shaped structure to optimize displacement characteristics. The flexible metal diaphragm is metallurgically bonded to the surrounding substrate of the cavity through vacuum brazing (or electron beam welding, laser welding). The distance between its outer surface and the working surface of the contact is 0.8–1.2 mm, forming a reliable sealing interface.

[0034] The capillary wick structure is located at the bottom of the cavity and is made of sintered copper powder, sintered stainless steel powder, metal foam or microporous ceramic. Its structure can be a sintered column, metal mesh or fiber sintered material with a porosity of 45%-55%. It is laid at the bottom of the cavity and, through its strong capillary force, ensures that after the phase change working fluid condenses, regardless of the spatial orientation of the contacts (including the case where the device is inverted, i.e., the heating area is above), the liquid working fluid can be actively and reliably pumped back to the heating area below the diaphragm, realizing the continuous circulation of the working fluid.

[0035] The width, radius, depth, and other dimensions of the cavity can be adaptively adjusted according to different current ratings and contact sizes.

[0036] Example 2:

[0037] Based on Example 1, the working principle of the contact structure of the present invention is as follows:

[0038] like Figure 3 , Figure 4As shown, when a vacuum circuit breaker interrupts a large current, the moving and stationary contacts separate and ignite a vacuum arc. When the highly concentrated anode spot resides on the working surface above the arc dissipation device, the high-density heat flux generated is transmitted into the cavity through the flexible metal diaphragm in a very short time. This causes the low-boiling-point working fluid adjacent to the diaphragm to be instantly heated to a superheated state and vaporized. The phase change process of the working fluid creates a pulsed vapor pressure in the sealed cavity. This pressure is sufficient to overcome the elasticity of the flexible diaphragm, driving it to produce a rapid, slight upward convex deformation. This causes continuous high-frequency, slight fluctuations on the contact surface. The surface fluctuations change the geometry of the contact surface and also cause continuous changes in the electric field distribution and heat flux density on the anode surface. Consequently, the arc spot cannot maintain stable thermal and electron emission at a fixed position. This synergistic effect of multiple physics fields deprives the arc spot of its stable environment. When it attempts to remain in a certain location, surface fluctuations in that area interrupt heat accumulation by altering the local heat flux density distribution. Meanwhile, morphological changes in adjacent areas provide new potential attachment points, forcing the arc root to continuously migrate across the anode surface, forming a "wandering" motion pattern. This disperses the concentrated energy input over a larger area and time span on the contact surface. Because the residence time of the arc spot at each location is significantly shortened, no single point on the anode surface can accumulate enough heat to cause severe ablation, thus suppressing concentrated ablation at its source. After the arc moves away or the current crosses zero, the heat source disappears, the vapor inside the cavity condenses through heat conduction, the pressure drops sharply, and the flexible metal diaphragm recovers its flatness under its own elasticity. Simultaneously, the capillary wick structure uses its capillary pumping action to return the condensed liquid working fluid to the bottom of the cavity, preparing for the next arc thermal effect. The entire process is an adaptive cyclic process driven entirely by the arc's own energy.

[0039] Example 3:

[0040] Based on Example 1, the present invention provides a contact structure with active vacuum arc dissipation function driven by internal phase change, which is specifically prepared by the following method:

[0041] Step 1: Prepare stationary and moving side contact pieces using CuCr50 alloy, and connect their bottoms to the corresponding conductive rods by threads or welding; process a cuboid cavity below the working surface of the contact.

[0042] Step 2, preparation of capillary core structure: Select 100-mesh copper powder, press and sinter at 850-950℃, hold for 50-70 minutes to form a porous structure layer with a porosity of 45%-55%, and fix it at the bottom of the cavity.

[0043] Step 3: In an inert gas atmosphere, liquid gallium indium tin alloy is injected into the cavity through a precision liquid injection system, and the injection volume is controlled to be 25%–35% of the effective volume of the cavity, so as to achieve optimized matching between the working fluid phase change characteristics and the electric arc heating process.

[0044] Step 4: Select a flexible beryllium copper alloy diaphragm with a thickness of 0.4–0.5 mm, and apply it to a vacuum level higher than 5 × 10⁻⁶. -3 In an environment of Pa, silver-based brazing filler metal is used to perform vacuum brazing at 700-800℃ to achieve hermetic encapsulation of the diaphragm and the cavity substrate processed in step 1.

[0045] Step 5, Performance Verification and Debugging

[0046] The airtightness of the encapsulated contact structure was tested, and the working fluid phase change response speed and diaphragm displacement were verified through on / off tests to ensure that the diaphragm can generate a displacement of not less than 100μm within 3ms under a 20kA breaking current condition, which meets the requirement of causing deformation of the contact surface to move the arc root.

[0047] Throughout the arc ablation process, the arc dispersing device provides continuous protection through a complete cyclic mechanism: From the initial state, when the arc first forms a spot on the anode surface, the device immediately enters the working medium heating stage, transferring arc energy to the working medium through heat conduction; subsequently, it enters the phase change triggering stage, where the working medium undergoes controlled vaporization at a suitable temperature, generating precisely controlled pulse pressure; next, it enters the mechanical intervention stage, where the sudden movement of the flexible diaphragm directly disrupts the stable adhesion of the arc spot; followed by the system reset stage, where pressure release and working medium recirculation are completed during the arc action interval; finally, it enters the cycle preparation stage, making full preparations to cope with subsequent arc actions. This complete mechanism ensures that the device can function continuously and stably throughout the entire arc ablation process, effectively suppressing the melting and ablation development of the anode surface through preventative mechanical intervention, thereby significantly improving the breaking performance and service life of the vacuum circuit breaker.

[0048] The theoretical explanation of the feasibility and effectiveness of the contact structure of this invention is as follows:

[0049] The method of this invention is feasible. First, from a thermodynamic perspective, the violent vaporization of low-boiling-point liquids upon heating by absorbing latent heat is a well-established physical mechanism. This invention innovatively introduces this principle into a vacuum arc environment, directly utilizing the high-density heat flow generated by the arc itself as energy input, resulting in a direct and efficient energy transfer path. Under actual operating conditions, the vacuum arc heat flow can rapidly vaporize the low-boiling-point working fluid within milliseconds, generating a driving pressure of several thousand Pascals. This pressure level is sufficient to overcome the elastic deformation of the flexible diaphragm and drive its operation. Second, regarding the working fluid circulation, the capillary wick structure used in the arc dissipation device draws inspiration from heat pipe technology widely used in aerospace thermal control and electronic heat dissipation. This technology has been thoroughly verified, demonstrating that porous capillary materials can achieve automatic and efficient circulation of the working fluid through stable capillary action. In the contact of this invention, this capillary wick structure ensures that the liquid working fluid can be reliably pumped back to the heat source area below the diaphragm after each operation, thereby achieving continuous and stable circulation. Finally, in terms of manufacturing processes, the acquisition and maintenance of a high vacuum environment, as well as high-airtightness packaging processes (such as vacuum brazing), are mature technologies in the vacuum circuit breaker manufacturing industry. The beryllium copper alloy flexible diaphragm, CuCr contact substrate, and related brazing processes used in this invention all possess good vacuum compatibility and process adaptability, thus effectively guaranteeing the realization of the core of the device—the closed-loop system—at the manufacturing level.

[0050] This invention generates high-frequency, micro-amplitude fluctuations on the anode contact surface, continuously altering the adhesion environment of the arc spot and preventing it from remaining stably in any one location. This forces the arc root to continuously move along the working surface before the anode surface temperature reaches the material's melting point, dispersing concentrated heat from the energy input source. This fundamentally changes the anode energy transmission distribution, suppressing the peak temperature in the anode region below the threshold for severe ablation. The significant reduction in ablation directly translates to an extended electrical life. Simultaneously, this technology effectively maintains the flatness of the anode working surface, which is beneficial for maintaining higher insulation recovery strength, thereby further improving the circuit breaker's breaking success rate.

[0051] Example 4:

[0052] In this embodiment, the substrate of the stationary and moving contact plates of the contact structure is made of CuCr alloy material, and both are cylindrical structures with a diameter of 60mm and a thickness of 5mm.

[0053] A rectangular sealed cavity measuring 18mm × 18mm × 2mm is provided below the working surface of the contact plate. A flexible beryllium copper alloy diaphragm with a thickness of 0.5mm is welded to the top of the cavity using a vacuum brazing process. The distance between the surface of the diaphragm and the working surface of the contact plate is 1mm. The determination of these structural parameters is based on the design requirement that the ablation depth does not exceed 1mm. This ensures that the arc dispersal device can intervene in time and provide effective protection before the ablation develops to a dangerous level.

[0054] The low-boiling-point working fluid is selected as liquid gallium indium tin alloy, with a boiling point of 1573K, lower than the melting point of the contact material CuCr50 (1745K). The filling amount is precisely calculated and determined to be 30% of the effective cavity volume, i.e., 0.194mL. The capillary core structure is made of 100-mesh copper powder through a sintering process, with the thickness controlled at 0.5mm and the porosity maintained at 50% to ensure good capillary action.

[0055] This embodiment also prepared a conventional contact structure, which does not have an arc dissipation device, and the rest of the structure is the same as the contact in this embodiment.

[0056] A 20kA breaking current cycle test was performed on the contacts of this embodiment and the conventional contacts. The results are as follows:

[0057] After 100 switching operations, the working surface of the contact in this embodiment showed no obvious ablation pits, and the surface roughness remained below Ra0.8μm; after the same test, the conventional contact showed obvious ablation pits, and the roughness increased to above Ra3.2μm.

[0058] Insulation recovery strength test shows that the insulation strength of the contact in this embodiment recovers to 90% of the initial value within 10ms after breaking, while the traditional contact only recovers to 65%, proving that the contact of the present invention can effectively maintain insulation performance.

[0059] Example 5:

[0060] This embodiment verifies the effectiveness of the arc dispersal device during its operation through theoretical calculations:

[0061] Considering the lack of accurate vapor pressure data for liquid gallium indium tin alloy in the high-temperature region in the published literature, and the fact that the actual electric arc process is a highly transient and non-equilibrium process, this embodiment, based on engineering rationality and conservative design principles, presets the saturated vapor pressure of liquid gallium indium tin alloy near its boiling point to be 0.5 MPa.

[0062] Based on a preset working pressure, the expected elastic displacement of a 0.5mm thick beryllium copper alloy diaphragm was calculated and analyzed. The small-deflection thin-plate bending theory was adopted, using the formula ω_max = α × (P × a) for the center deflection of a square thin plate with four fixed sides. 4 The calculation is performed using (E×h³), where the coefficient α = 0.044 and the pressure P = 0.5×10⁻⁶. 6 Given a beryllium copper alloy diaphragm with a side length of a = 0.018 m, an elastic modulus E = 1.28 × 10¹¹ Pa, and a thickness h = 0.0005 m, detailed calculations yield a central deflection ω_max = 0.144 mm. This result satisfies the conditions for the small deflection theory, and the calculated ratio of deflection to diaphragm thickness is 0.288, which is less than 0.3, thus verifying the applicability of the theory.

[0063] Stress analysis of the diaphragm was performed under the same operating conditions. The maximum stress σ_max = β × (P × a²) / h² was calculated using the formula for a square thin plate with four fixed sides, where the coefficient β = 0.5. Other parameters were kept consistent with the displacement calculation, ultimately yielding a maximum stress σ_max = 324 MPa. This stress level is significantly lower than the yield strength of beryllium copper alloy (1100 MPa), indicating that the structural design has a sufficient safety margin.

[0064] Detailed calculations of diaphragm displacement and stress demonstrated that, at a preset working pressure of 0.5 MPa, the design using a 0.5 mm thick beryllium copper diaphragm can generate an effective displacement of 0.144 mm while ensuring that the working stress of 324 MPa remains within a safe range. The displacement magnitude is sufficient to effectively prevent stable arc spot residence by continuously altering the microstructure and electric field distribution of the anode surface, while the stress level ensures the integrity of the device and prevents damage due to excessive stress. The actual working pressure can be controlled using conventional engineering techniques such as adjusting the working fluid filling amount.

[0065] Example 6:

[0066] This embodiment uses the professional finite element analysis software COMSOL Multiphysics to establish a simulation model to verify the effectiveness of the arc dispersal device of the present invention.

[0067] In terms of model construction, two comparative simulation models were established: a traditional anode model and the anode model of the present invention. The traditional anode model adopts a solid cylindrical structure; the anode model of the present invention has a rectangular sealed cavity structure with dimensions of 18mm×18mm×2mm set 1mm below the anode working surface.

[0068] The key parameters of both models are set based on actual working conditions: the anode contact substrate material is CuCr50 alloy, and the structure is designed as a cylinder with a diameter of 60mm and a thickness of 5mm. The simulation conditions are: breaking current of 20kA, total simulation time of 10ms, using a transient solver with a time step of 0.1ms to meet the requirements for accurate analysis of the dynamic characteristics of the arc.

[0069] Mesh generation was performed using a physics-controlled method, with localized mesh refinement in the arc-affected region and around the cavity structure. The minimum element size was 0.02 mm, and the maximum element size was 1 mm, with the overall mesh quality maintained above 0.7. Mesh independence verification confirmed that the impact of mesh density on key calculation results was less than 1.5%, ensuring the reliability of the simulation results.

[0070] In terms of the physical field setup, the simulation model couples multiple physical modules: the heat conduction module includes the electric arc heat source and the latent heat of phase change. Based on existing research data, the arc heat flux density under a 20kA breaking current condition is taken as 1.2 × 10⁻⁶. 9 W / m²; the fluid dynamics module uses a laminar flow model and includes phase change interface tracking functionality; the solid mechanics module is based on a linear elastic model and is used to analyze the deformation behavior of flexible diaphragms. A fully bidirectional coupling relationship is established between all physical fields.

[0071] In the boundary condition settings, the contact base is set as a 300K isothermal boundary, and the convective heat dissipation effect is considered on the outer surface. For structural constraints, the periphery of the diaphragm is set as a fixed boundary, and the internal wall of the cavity is subject to pressure loads. Key material parameters are set using experimentally measured values: CuCr50 has a thermal conductivity of 110 W / (m·K) and a specific heat capacity of 380 J / (kg·K); beryllium copper alloy has an elastic modulus of 128 GPa and a yield strength of 1100 MPa; and the latent heat of vaporization of liquid gallium indium tin alloy is taken as 285 kJ / kg.

[0072] Simulation results are as follows Figure 5 As shown, the conventional anode without an arc-dissipating device reaches the melting point of CuCr50 (1745K) at its center approximately 4ms after arc initiation, and reaches its maximum temperature (approximately 2800K) at approximately 7ms. In contrast, under the same operating conditions, the peak surface temperature of the anode structure with the arc-dissipating device of this invention is consistently and effectively suppressed below the melting point of CuCr50 material. This indicates that the arc-dissipating device can effectively control the anode surface temperature, significantly reducing melting and preventing severe ablation caused by intense vaporization. Particularly noteworthy is that the anode of this invention provides effective intervention 3ms after the onset of ablation, much earlier than the 4ms required for the material to reach its melting point, demonstrating its excellent preventative protective characteristics.

[0073] In summary, this embodiment, through specific structural design parameters and rigorous theoretical calculations and simulation analysis, fully demonstrates that the arc dissipation device of this invention can effectively suppress anodic ablation under 20kA breaking conditions, significantly improving the breaking performance and service life of the vacuum circuit breaker. The structural arrangement of the device ensures effective early intervention while maintaining an ablation depth of no more than 1mm, demonstrating significant engineering application value.

Claims

1. A contact structure with active vacuum arc dissipation function based on internal phase change drive, characterized in that, It includes a stationary contact piece, a stationary conductive rod fixedly connected to the stationary contact piece, a moving contact piece disposed opposite to the stationary contact piece, and a moving conductive rod fixedly connected to the moving contact piece. An arc dispersing device is provided inside both the stationary contact piece and the moving contact piece, and the two arc dispersing devices are symmetrically arranged with the radial center line of the contact structure as the axis of symmetry. The arc dispersing device is a hollow sealed structure, which is located close to the working surface of the contact, with the surface 0.8–1.2 mm away from the working surface of the contact. The arc dispersing device has a flexible metal diaphragm near the contact surface, which is filled with a liquid low-boiling-point working fluid, and a capillary core structure made of porous sintered material is provided at the bottom.

2. The contact structure with active vacuum arc dissipation function based on internal phase change drive according to claim 1, characterized in that, The boiling point of the low-boiling working fluid is between 800K and 1600K, and its physicochemical properties are stable.

3. The contact structure with active vacuum arc dissipation function based on internal phase change drive according to claim 1, characterized in that, The filling volume of the low-boiling-point working fluid is 25%-35% of the effective volume of the cavity.

4. The contact structure with active vacuum arc dissipation function based on internal phase change drive according to claim 1, characterized in that, The flexible metal diaphragm has a thickness of 0.4-0.5 mm and is made of beryllium copper alloy, Hastelloy, special stainless steel or titanium alloy with an elastic modulus of 100-200 GPa and fatigue strength >300 MPa.

5. The contact structure with active vacuum arc dissipation function based on internal phase change drive according to claim 1, characterized in that, The capillary core structure is made of sintered copper powder, sintered stainless steel powder, metal foam or microporous ceramic material, and its porosity is 45%-55%.

6. The contact structure with active vacuum arc dissipation function based on internal phase change drive according to claim 1, characterized in that, The specific preparation method of the arc dispersal device is as follows: Cavities are machined inside the stationary and moving contact plates. A capillary wick structure is placed at the bottom of the cavity. A low-boiling-point working fluid is injected into the cavity through a precision liquid injection system, and the injection volume is controlled to be 25%–35% of the effective volume of the cavity. The periphery of the flexible metal diaphragm is welded to the inner wall of the cavity through vacuum brazing, electron beam welding or laser welding.

Images