Double-layer arc extinguishing flat plate type fuse

Abstract

The invention relates to the technical field of circuit protection devices, in particular to a double-layer arc-extinguishing flat plate type fuse which comprises an insulating shell, a melt and a composite arc-extinguishing core, the melt is provided with a center fusing area and a terminal area which are integrally formed, and the composite arc-extinguishing core is arranged in the insulating shell and surrounds the center fusing area. A first arc extinguishing cavity for accommodating a gas production material is formed in the first arc extinguishing chamber to form a first arc extinguishing layer; and a second arc extinguishing cavity filled with an arc extinguishing medium is formed between the insulating shell and the composite arc extinguishing core body to form a second arc extinguishing layer. According to the invention, during breaking, high-pressure airflow can be quickly generated to suppress electric arcs in a segmented manner, and continuous cooling and insulation are realized by an external medium, so that the arcing time is greatly shortened, the internal pressure is effectively controlled, the shell is prevented from bursting, and the breaking capacity, safety and reliability of high-voltage and large-current faults are remarkably improved.

Description

A double-layer arc-extinguishing flat-plate fuse Technical Field

[0001] This invention relates to the field of circuit protection device technology, specifically to a double-layer arc-extinguishing flat fuse. Background Technology

[0002] As a key component in circuit protection, the fuse's core function is to quickly disconnect the circuit in the event of an overcurrent fault, thereby protecting the safety of downstream electrical equipment. With the continuous improvement of power system voltage levels and short-circuit capacity, higher requirements are placed on the breaking capacity and arc-extinguishing performance of fuses. Currently, common flat-plate fuses typically enhance the arc-extinguishing effect by placing a single type of arc-extinguishing material (such as quartz sand, silica gel, or silicate particles) within the insulating housing, and structurally employ a lead-out terminal directly connected to the fusible element to achieve melting and circuit isolation under fault current.

[0003] However, existing planar fuses still have the following obvious limitations in practical applications: On the one hand, the arc-extinguishing design of existing planar fuses is often relatively simple, and the suppression of arc mainly relies on the physical cooling and insulation effect of the filling material, lacking an effective control and segmented isolation mechanism for the generation and development of arc; on the other hand, existing planar fuses are limited by their arc-extinguishing capacity, and are prone to problems such as excessively long arcing time and rapid increase in internal pressure when interrupting high-energy fault currents, which may lead to shell rupture or even arcing, affecting not only the reliability of interruption but also posing a threat to the safety of surrounding equipment and personnel.

[0004] The above reasons together result in the insufficient breaking capacity of existing flat-plate fuses in high-voltage, high-current scenarios, making it difficult to quickly and completely disconnect fault current while ensuring safety and reliability. Summary of the Invention

[0005] To address the above technical problems, this invention provides a technical solution for a double-layer arc-extinguishing flat-plate fuse.

[0006] The technical problem solved by this invention can be achieved by the following technical solution: a double-layer arc-extinguishing flat fuse, comprising: an insulating shell; a fusible element having an integrally formed central fusing region and a terminal region, the central fusing region being located inside the insulating shell, and the terminal region being exposed outside the insulating shell; a composite arc-extinguishing core disposed inside the insulating shell and surrounding the central fusing region; wherein, a first arc-extinguishing cavity is formed inside the composite arc-extinguishing core, the first arc-extinguishing cavity containing a gas-generating material to form a first arc-extinguishing layer; a second arc-extinguishing cavity is formed between the insulating shell and the composite arc-extinguishing core, the second arc-extinguishing cavity being filled with an arc-extinguishing medium to form a second arc-extinguishing layer.

[0007] Preferably, the gas-generating material includes one or more of polytetrafluoroethylene, nylon, engineering plastic particles or fibers; the arc-quenching medium includes one or more of quartz sand, silicate ceramic particles, alumina microspheres, melamine, sulfur hexafluoride, and epoxy resin.

[0008] Preferably, the insulating housing includes an upper cover housing and a lower cover housing, which are fixedly connected by fasteners.

[0009] Preferably, the composite arc-extinguishing core includes: an upper seat body, detachably installed inside the upper cover housing; a lower seat body, detachably installed inside the lower cover housing; and two arc-extinguishing inner shells, which are respectively engaged on the upper and lower sides of the central melting area and located between the upper seat body and the lower seat body; the upper seat body, the lower seat body, and the two arc-extinguishing inner shells together form the first arc-extinguishing cavity.

[0010] Preferably, the upper cover shell has an upper cover groove, and the upper seat has an upper seat protrusion, which engages with the upper cover groove; the lower cover shell has a lower cover groove, and the lower seat has a lower seat protrusion, which engages with the lower cover groove; the arc-extinguishing inner shell is made of ceramic or engineering plastic, and the arc-extinguishing inner shell has an arc-extinguishing inner cover groove, which engages with the central melting area.

[0011] Preferably, the upper cover shell is provided with a half hole, the upper seat body is provided with an upper seat body through hole surface, the lower seat body is provided with a lower seat body through hole surface, and the arc-extinguishing inner shell is provided with an arc-extinguishing inner cover through hole surface; after assembly, the half hole, the upper seat body through hole surface, the lower seat body through hole surface, and the arc-extinguishing inner cover through hole surface together form a through hole for filling the second arc-extinguishing cavity with the arc-extinguishing medium.

[0012] Preferably, the upper cover housing is provided with a first limiting post and a first limiting hole on both sides, and the lower cover housing is provided with a second limiting post and a second limiting hole on both sides; during assembly, the first limiting post is inserted into the second limiting hole, and the second limiting post is inserted into the first limiting hole.

[0013] Preferably, there is a transition region between the central melting region of the melt and the terminal region, and a second mounting hole is provided on the transition region.

[0014] Preferably, the upper cover housing has a first mounting hole and the lower cover housing has a third mounting hole; during assembly, fasteners pass through the first mounting hole, the second mounting hole and the third mounting hole in sequence to fix the molten material to the insulating shell.

[0015] Preferably, the melt is a silver or copper alloy strip.

[0016] Beneficial effects: This invention forms a double-layered, complementary arc-extinguishing structure by setting up a composite arc-extinguishing core around the central melting area of ​​the melt, with a first arc-extinguishing cavity containing gas-generating material inside and a second arc-extinguishing cavity filled with arc-extinguishing medium outside the core. This structure can rapidly generate high-pressure airflow during the breaking process to suppress and cool the arc in stages. At the same time, the external medium provides sufficient insulation and continuous arc extinguishing effect, thereby significantly shortening the arcing time, effectively controlling the internal pressure and preventing the outer shell from bursting. This significantly improves the fuse's breaking capacity and safety reliability for high-voltage and high-current faults. Attached Figure Description

[0017] Figure 1 is a structural schematic diagram of the double-layer arc-extinguishing flat plate fuse of the present invention; Figure 2 is an exploded view of the structure of the double-layer arc-extinguishing flat plate fuse of the present invention; Figure 3 is a cross-sectional view of the structure of the double-layer arc-extinguishing flat plate fuse of the present invention; Figure 4 is a structural schematic diagram of the upper cover shell of the present invention; Figure 5 is a structural schematic diagram of the outer surface of the upper cover shell of the present invention; Figure 6 is a structural schematic diagram of the lower cover shell of the present invention; Figure 7 is a structural schematic diagram of the inner surface of the lower cover shell of the present invention; Figure 8 is a structural schematic diagram of the upper seat body of the present invention; Figure 9 is a structural schematic diagram of the lower seat body of the present invention; Figure 10 is a structural schematic diagram of the arc-extinguishing inner shell of the present invention.

[0018] Figure descriptions: 1. Insulating outer shell; 2. Molten material; 3. Rivet; 4. Through hole; 5. Upper seat; 6. Lower seat; 7. Arc-extinguishing inner shell; 8. Arc-extinguishing structure; 11. Upper cover shell; 111. Upper cover groove; 112. Half hole; 113. First mounting hole; 114. First limiting post; 115. First limiting hole; 116. First receiving through hole; 12. Lower cover shell; 121. Lower cover groove; 122. Third mounting hole ; 123, Second limiting post; 124, Second limiting hole; 125, Second receiving through hole; 21, Central fusion area; 22, Terminal area; 23, Transition area; 24, Second mounting hole; 51, Upper seat protrusion; 52, Upper seat through hole surface; 61, Lower seat protrusion; 62, Lower seat through hole surface; 71, Arc extinguishing inner cover groove; 72, Arc extinguishing inner cover through hole surface; 81, First arc extinguishing cavity; 82, Second arc extinguishing medium. Detailed Implementation

[0019] The technical solutions of the embodiments 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.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0021] The present invention will be further described below using an automotive-grade fuse with a rated voltage of 220VDC, a rated current of 650A, and a required breaking capacity of 50kA as an example, in conjunction with the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0022] Referring to Figures 1 to 3, the present invention provides a double-layer arc-extinguishing flat-plate fuse, comprising: an insulating shell 1; a fusible element 2, the fusible element 2 having an integrally formed central fusing region 21 and a terminal region 22, the central fusing region 21 being located inside the insulating shell 1, and the terminal region 22 being exposed outside the insulating shell 1; and a composite arc-extinguishing core 8, disposed inside the insulating shell 1 and surrounding the central fusing region 21; wherein, a first arc-extinguishing cavity 81 is formed inside the composite arc-extinguishing core 8, the first arc-extinguishing cavity 81 containing a gas-generating material to form a first arc-extinguishing layer; and a second arc-extinguishing cavity is formed between the insulating shell 1 and the composite arc-extinguishing core 8, the second arc-extinguishing cavity being filled with an arc-extinguishing medium 82 to form a second arc-extinguishing layer.

[0023] Specifically, in this embodiment of the invention, to address the problems of long arcing time, sudden increase in internal pressure, and insufficient breaking capacity of existing flat-plate fuses under high-energy fault currents, a double-layer arc-extinguishing cavity structure composed of a composite arc-extinguishing core is introduced to achieve segmented suppression and layer-by-layer extinguishing of the arc. The inner first arc-extinguishing layer rapidly generates a high-pressure airflow under the action of the arc to cool, impact, and segment the arc; the outer second arc-extinguishing layer provides durable insulation and arc extinguishing through the arc-extinguishing medium 82, thereby effectively shortening the arcing time, balancing the internal pressure, avoiding the risk of arcing or shell bursting, and significantly improving the safety and breaking reliability of the fuse in high-voltage, high-current scenarios.

[0024] Specifically, in practical applications, when an overcurrent fault occurs in the circuit, the central melting area 21 of the fuse 2 (i.e., the thinner fuse wire) melts rapidly and triggers an electric arc. The high temperature of the electric arc first acts on the composite arc-extinguishing core 8 surrounding it, causing the gas-generating material in the first arc-extinguishing cavity 81 to decompose rapidly, generating high-pressure gas that is injected into the arc channel. This process achieves initial arc extinguishing through the strong gas flow and cooling effect, while the generated gas pressure is also effectively constrained and utilized by the inner cavity of the shell. Subsequently, the residual arc energy is further absorbed by the arc-extinguishing medium 82 in the second arc-extinguishing cavity. Through the insulation, cooling, and separation effects between particles, the electric arc is completely extinguished and the circuit is reliably disconnected.

[0025] More specifically, referring to Figure 2, in this embodiment of the invention, the melt 2 is formed by stamping a single piece of conductive metal sheet, exhibiting a regular rectangular strip structure that is wide at both ends and narrow in the middle. Its main body adopts a centrally symmetrical design, which not only facilitates the uniform distribution of current but also ensures the stability and predictability of the melting behavior in the event of a fault.

[0026] The center of the melt 2 is precisely designed as a narrow region with a significantly reduced cross-section. This is the central melting region 21 of the fuse wire, which is the key part with the highest current density and is most likely to melt under overload.

[0027] The two ends of the melt 2 extend into large terminal areas 22. These areas are used not only for mechanical connection and electrical conduction with external circuits, but their increased cross-sectional area also ensures low contact resistance and temperature rise during normal operation. Each terminal area 22 is provided with at least one circular hole, which facilitates reliable and secure installation and fixing to external busbars or connecting bars by fasteners such as bolts or screws.

[0028] Accordingly, referring to Figure 1, the insulating housing 1 is a flat rectangular box-shaped structure used to house and protect all internal components, and its outer contour is adapted to the shape of the rectangular strip-shaped molten material 2. Arc-shaped openings matching the shape of the terminal areas 22 are provided on the side walls at both ends of this box-shaped structure, allowing the two terminal areas 22 of the molten material 2 to extend precisely from both ends of the insulating housing 1 and be exposed to the external environment for connection. The central molten area 21 and the entire double-layer arc-extinguishing structure are completely sealed inside the insulating cavity of the housing, thus achieving an integrated design of electrical isolation and mechanical protection.

[0029] In a preferred embodiment of the present invention, the melt 2 is a silver or copper alloy strip with a thickness of 1.5-2.0 mm.

[0030] Specifically, considering the comprehensive requirements of high voltage and high current application scenarios for melt conductivity, thermal stability and mechanical strength, in this embodiment of the invention, a silver or copper alloy strip with high conductivity is preferably used as melt 2, and its thickness is limited to the range of 1.5-2.0 mm.

[0031] Among them, silver material has extremely low resistivity and stable chemical properties, which can ensure low power consumption and long life under normal operating conditions. When a fault current occurs, it can achieve precise and rapid melting due to its rapid heat accumulation characteristics, creating favorable starting conditions for the subsequent arc extinguishing process.

[0032] Copper alloys, while ensuring good electrical conductivity, have higher mechanical strength and better economy. By adjusting the alloy composition, their melting point, tensile strength and resistance to arc erosion can be further optimized, thereby maintaining the integrity of the melt structure until complete breakage under complex working conditions.

[0033] This material selection enables the fuse 2 to work efficiently with the double-layer arc-extinguishing structure. The fuse 2 acts quickly to limit the peak value and duration of the short-circuit current, and then the double-layer arc-extinguishing structure quickly intervenes to safely break the circuit, thus ensuring the overall high breaking capacity, reliability and safety of the fuse.

[0034] As can be seen, the above design takes into account both low resistance loss and sufficient current-carrying cross-sectional area, ensuring that the temperature rise is controllable and the operation is reliable during normal operation. At the same time, the thickness provides a material basis and heat capacity conditions for the integrated central fusing area 21 (the thinner fuse), enabling it to quickly reach the melting point and form a break under fault current. The structural strength brought by the thickness also enhances the stability of the fuse 2 as a whole under high-temperature arc impact, laying a solid foundation for the effective coordinated action of the double-layer arc extinguishing structure, thereby improving the rapid breaking capability and short-circuit impact resistance of the entire fuse.

[0035] In a preferred embodiment of the present invention, the gas-generating material includes one or more of polytetrafluoroethylene, nylon, engineering plastic particles or fibers; the arc-extinguishing medium 82 includes one or more of quartz sand, silicate ceramic particles, alumina microspheres, melamine, sulfur hexafluoride, and epoxy resin.

[0036] Specifically, in order to construct a dual-layer collaborative mechanism that can achieve active, rapid, and reliable arc extinguishing to completely solve the problem of arcing and disconnection under high-energy fault current, in this embodiment of the invention, two functionally complementary arc extinguishing materials are placed in the first arc extinguishing cavity inside the composite arc extinguishing core 8 and the second arc extinguishing cavity between the insulating shell 1 and the composite arc extinguishing core 8, respectively. This forms a closely coordinated dual-layer structure in terms of physical space and functional timing, thereby achieving effective control over the entire process of arc generation and extinction, and ultimately obtaining a comprehensive effect of rapid current limiting, efficient cooling, and stable insulation.

[0037] Specifically, the gas-generating material constituting the first arc-extinguishing layer is selected from one or more organic materials with specific thermal decomposition characteristics, such as polytetrafluoroethylene (PTFE), nylon, or particles or fibers of special engineering plastics. This first arc-extinguishing layer, as an active reaction layer, tightly surrounds the central melting region 21 of the melt 2. Under the high temperature generated by the electric arc, these materials will rapidly decompose, producing a large amount of non-flammable inert gases (such as fluorocarbons, nitrogen, carbon dioxide, etc.). These gases form a strong arc-blowing effect in the cavity, which can generate a strong "arc-blowing" effect, actively driving the arc movement and dividing it, thereby achieving a rapid increase in arc voltage and initial current limiting in the first instance.

[0038] Accordingly, the arc-extinguishing medium constituting the second arc-extinguishing layer is selected from inorganic particulate materials with high heat capacity and high insulation strength, such as high-purity quartz sand (SiO2 content > 99.9%), silicate ceramic particles, alumina microspheres, melamine, sulfur hexafluoride, epoxy resin, etc., which have high thermal stability, high insulation strength, and excellent heat absorption and deionization properties. This second arc-extinguishing layer, as a steady-state absorption and insulation recovery layer, fills the second arc-extinguishing cavity between the insulating shell 1 and the composite arc-extinguishing core 8, covering the first arc-extinguishing layer. This layer not only effectively absorbs and dissipates the huge heat generated from the electric arc and the reaction of the first layer, but also further cools and divides the electric arc plasma by utilizing the interparticle gaps, and rapidly establishes a stable, highly insulating channel after the arc is extinguished to prevent arc reignition.

[0039] This design enables the first and second arc-extinguishing layers to form a synergistic relationship of "active impact + steady-state absorption" during the breaking process. The former reacts quickly first, achieving active impact and initial current limiting, while the latter subsequently plays its main role, providing continuous cooling and final insulation. The two layers are closely integrated in timing and function, together forming a highly efficient and reliable dual arc-extinguishing system, significantly improving the fuse's breaking capacity and safety.

[0040] In a preferred embodiment of the present invention, the insulating outer shell 1 includes an upper cover shell 11 and a lower cover shell 12, wherein the upper cover shell 11 and the lower cover shell 12 are fixedly connected by fasteners.

[0041] Specifically, in order to reliably encapsulate the internal melt 2, the composite arc-extinguishing core 8, and the arc-extinguishing medium 82, facilitate assembly, and ensure structural integrity and sealing during the breaking process, a split-shell design is adopted in this embodiment of the invention.

[0042] Specifically, referring to Figure 1, the insulating outer shell 1 is a flat rectangular box-shaped structure. Referring to Figures 2 and 3, this structure consists of two independent components, the upper cover shell 11 and the lower cover shell 12, which are firmly connected by fasteners (such as bolts, screws, rivets, etc.) arranged along their edges. Its flat rectangular shape not only occupies little space but also fits perfectly with the shape of the internal rectangular strip-shaped melt 2, achieving a compact layout.

[0043] The use of fasteners for fixed connection not only ensures the tight closure of the upper and lower cover shell mating surfaces, preventing leakage of the arc extinguishing medium, but also provides convenience for assembly and necessary maintenance, while ensuring the mechanical strength of the separation cavity when internal gas generation and pressurization are carried out.

[0044] The composite arc-extinguishing core 8 is located in the center of the shell. The first arc-extinguishing cavity 81 inside it (containing the gas-generating material) and the second arc-extinguishing cavity outside the core (filled with the arc-extinguishing medium 82) together constitute a complete double-layer arc-extinguishing structure.

[0045] This split-shell design encapsulates the complex internal arc-extinguishing structure within a robust and sealed insulating container, facilitating production assembly and quality control while providing a controlled and safe spatial environment for the arc extinguishing process. It is a key structural foundation for ensuring the high performance and high reliability of the entire fuse.

[0046] In a preferred embodiment of the present invention, the composite arc-extinguishing core 8 includes: an upper seat 5, detachably mounted on the inner side of the upper cover housing 11; a lower seat 6, detachably mounted on the inner side of the lower cover housing 12; and two arc-extinguishing inner shells 7, which are respectively engaged on the upper and lower sides of the central melting region 21 and located between the upper seat 5 and the lower seat 6; the upper seat 5, the lower seat 6, and the two arc-extinguishing inner shells 7 together form the first arc-extinguishing cavity 81.

[0047] Specifically, in order to efficiently and reliably construct a double-layer arc-extinguishing structure surrounding the central melting region 21 of the melt 2, facilitate the filling and replacement of gas-generating materials, and realize modular assembly of components, in this embodiment of the invention, the composite arc-extinguishing core 8 is designed as a split structure composed of an upper seat 5, a lower seat 6, and two arc-extinguishing inner shells 7.

[0048] Specifically, firstly, referring to Figure 4, a rectangular first receiving through hole 116 is provided in the central area of ​​the upper cover housing 11. Its size matches the outer contour of the upper seat 5. The upper seat 5 is installed and fitted into the first receiving through hole 116 through its mounting structure, thereby realizing its positioning and fixation inside the upper cover housing 11.

[0049] Similarly, referring to Figure 6, a corresponding rectangular second receiving through hole 125 is provided in the central region of the lower cover housing 12, and the lower seat 6 is installed in the second receiving through hole 125 in a similar manner.

[0050] Next, referring to Figure 2, the two arc-extinguishing inner shells 7 are tightly engaged on the upper and lower sides of the central melting region 21 of the melt 2 through a locking structure, and are located between the upper seat 5 and the lower seat 6.

[0051] Referring to Figure 8, the upper seat 5 is a rectangular box structure with a sealed top and an open bottom, providing support and enclosure for the structure below. Referring to Figure 9, the lower seat 6 is also a rectangular box structure with a sealed bottom and an open top, used to enclose from below. Referring to Figure 10, the arc-extinguishing inner shell 7 is a rectangular hollow frame structure with an internal cavity through which the molten material 2 passes. The rectangular outer frames of the upper seat 5, lower seat 6, and arc-extinguishing inner shell 7 are the same size and are stacked in the order of "upper seat 5 - two arc-extinguishing inner shells 7 - lower seat 6" from top to bottom. This stacking is mainly achieved by gravity, shell constraints, and close fit between the components, with simple spatial placement and alignment, thus simplifying the assembly steps.

[0052] Ultimately, they together construct a closed, precisely sized first arc-extinguishing cavity 81 around the central melting region 21 of the melt 2.

[0053] The aforementioned split and modular design not only facilitates assembly and filling of gas-generating materials, but also allows each part to be manufactured and replaced independently, improving production flexibility and maintenance convenience, while ensuring the accuracy and reliability of the first arc-extinguishing layer structure.

[0054] In a preferred embodiment of the present invention, the upper cover housing 11 is provided with an upper cover groove 111, and the upper seat body 5 is provided with an upper seat body protrusion 51, which engages in the upper cover groove 111; the lower cover housing 12 is provided with a lower cover groove 121, and the lower seat body 6 is provided with a lower seat body protrusion 61, which engages in the lower cover groove 121.

[0055] Specifically, the upper seat 5 and the lower seat 6 are key support structures for the composite arc-extinguishing core 8. In order to achieve precise positioning, prevent circumferential rotation, and maintain stability when subjected to internal pressure after assembly, the present invention adopts a locking positioning method in which protrusions and grooves cooperate with each other.

[0056] Specifically, referring to Figures 2 and 4, rectangular or trapezoidal upper cover grooves 111 facing inward are respectively formed around the inner wall of the first receiving through hole 116 of the upper cover housing 11. These grooves are evenly distributed along the hole wall. Referring to Figures 2 and 8, an outwardly protruding upper seat protrusion 51 is integrally formed around the corresponding position of the outer side wall of the upper seat 5. Its shape matches the upper cover groove 111. When the upper seat 5 is inserted into the first receiving through hole 116, these protrusions 51 will accurately fit into the corresponding grooves 111.

[0057] Similarly, referring to FIGS. 2, 6 and 7, a lower cover groove 121 is respectively formed around the inner wall of the second accommodation through hole 125 of the lower cover housing 12; referring to FIG. 9, at corresponding positions around the outer side wall of the lower seat body 6, a lower seat body protrusion 61 protruding outward is respectively provided. When assembling the lower seat body 6, its protrusion 61 will also snap into the lower cover groove 121.

[0058] The above-mentioned snap-fit of the protrusion and the groove realizes the non-rotating fixation and precise alignment of the upper and lower seat bodies in the housing mounting hole, ensures the structural stability of the first arc extinguishing cavity 81 enclosed by them, and can effectively transmit and disperse the force brought by the internal air pressure, enhancing the structural reliability of the entire composite arc extinguishing core.

[0059] As a preferred embodiment of the present invention, the arc extinguishing inner shell 7 is made of ceramic or engineering plastic. An arc extinguishing inner cover groove 71 is formed on the arc extinguishing inner shell 7, and the arc extinguishing inner cover groove 71 is engaged with the central fusing area 21.

[0060] Specifically, considering that the arc extinguishing inner shell 7 needs to be adjacent to the central fusing area 21 of the melt to construct an effective arc extinguishing cavity, its material must have excellent insulation, arc erosion resistance and high temperature stability. At the same time, reliable positioning with the melt needs to be achieved structurally. Based on this, in the embodiment of the present invention, the arc extinguishing inner shell 7 is preferably made of high purity alumina ceramic, high temperature resistant special engineering plastic (such as polyimide) or gas generating arc extinguishing coating and other materials. Alumina ceramic can effectively withstand the arc high temperature and maintain the structural integrity due to its extremely high insulation resistance, excellent high temperature strength and chemical inertness; special engineering plastics have excellent insulation, low density and good machining performance, which are convenient for making complex structures, and the heat resistance grade can meet the application requirements.

[0061] In addition, a special polymer coating with gas generating characteristics can also be coated or impregnated on the surface of the inner shell to strengthen the gas generating arc extinguishing effect in cooperation with the first arc extinguishing layer material when an arc occurs.

[0062] Furthermore, referring to FIG. 10, at the central positions of two opposite inner side walls of the arc extinguishing inner shell 7, an arc extinguishing inner cover groove 71 in the shape of "匚" and matching the thickness of the central fusing area 21 of the melt 2 is respectively formed. The opening side of the groove faces the central fusing area 21 of the melt, forming a three-sided surrounding engagement structure.

[0063] During assembly, referring to FIG. 2, the arc extinguishing inner cover grooves 71 of the two arc extinguishing inner shells 7 are respectively aligned from the up and down directions and snapped into both sides of the flat belt body of the central fusing area 21, so that the melt belt body is wrapped by the three sides of the groove and firmly limited, thereby realizing the precise and stable positioning of the arc extinguishing inner shell 7 on the melt 2.

[0064] This design not only ensures accurate and reliable positioning of the arc-extinguishing inner shell 7, but also guarantees electrical isolation between the first arc-extinguishing cavity 81 and the melt through its own insulation properties. At the same time, its high-temperature resistance ensures the structural integrity under arc impact, thus providing key physical structural support for the stable functioning of the first arc-extinguishing layer.

[0065] In a preferred embodiment of the present invention, the upper cover shell 11 is provided with a half hole 112, the upper seat 5 is provided with an upper seat through hole surface 52, the lower seat 6 is provided with a lower seat through hole surface 62, and the arc-extinguishing inner shell 7 is provided with an arc-extinguishing inner cover through hole surface 72; after assembly, the half hole 112, the upper seat through hole surface 52, the lower seat through hole surface 62, and the arc-extinguishing inner cover through hole surface 72 together form a through hole 4, which is used to fill the second arc-extinguishing cavity with the arc-extinguishing medium 82.

[0066] Specifically, in order to employ an efficient, reliable method that ensures dense filling, the granular arc-extinguishing medium 82 is filled into the second arc-extinguishing cavity formed between the insulating shell 1 and the composite arc-extinguishing core 8. In this embodiment of the invention, semi-cylindrical through-hole surfaces are designed on each of the separate components, and then aligned after final assembly, thereby forming a continuous vertical filling channel.

[0067] Specifically, firstly, referring to Figures 4 and 5, a semi-circular hole, namely a half-hole 112, is made inward at the four corners of the inner wall of the first receiving through hole 116 of the upper cover housing 11. The half-hole extends through the thickness direction of the upper cover housing.

[0068] Next, referring to Figure 8, a semi-cylindrical recess is formed at the corresponding positions of the four corners of the outer wall of the upper body 5, which is the through hole surface 52 of the upper body.

[0069] Meanwhile, referring to Figure 9, at the corresponding positions of the four corners of the outer wall of the lower body 6, a semi-cylindrical recess is also machined inward, which is the through hole surface 62 of the lower body.

[0070] Then, referring to Figure 10, for the two arc-extinguishing inner shells 7, a semi-cylindrical recess is also made at each of the four outer corners, namely the arc-extinguishing inner cover through hole surface 72.

[0071] In particular, considering that the lower body 6 needs to support the upper structure and bear the weight of the medium, its lower body through hole surface 62 is not completely through from top to bottom. Instead, a solid step of a certain height is designed at the bottom of its through hole surface structure. This step serves both as structural support and as a way to prevent the medium from leaking from the bottom when it is not sealed.

[0072] These semi-cylindrical surfaces distributed on each component are symmetrically arranged. After being stacked and aligned in the order of "upper cover shell 11 - upper seat 5 - two arc-extinguishing inner shells 7 - lower seat 6", the semi-cylindrical surfaces on adjacent components will be paired up in pairs, thereby forming four connected and complete cylindrical vertical through holes 4 at the four corners of the assembly (as shown in Figure 1). These through holes 4 constitute a filling channel from the outside of the outer shell to the inner second arc-extinguishing cavity.

[0073] Finally, the arc-extinguishing medium 82 (such as quartz sand) is fully and densely filled into the entire second arc-extinguishing cavity through the four through holes 4 using an automated vibration filling device.

[0074] After filling, high-temperature epoxy resin or silicone and other insulating sealants are used to seal and cure the half hole 112 on the top cover housing 11, ensuring that the medium does not leak out and achieving overall sealing and moisture protection.

[0075] In this way, the problem of filling the arc-extinguishing medium in the complex internal cavity is solved by the cleverly designed split-type filling channel structure, which ensures the uniformity and density of the second arc-extinguishing layer material, thereby guaranteeing its stable cooling and insulation performance.

[0076] In a preferred embodiment of the present invention, a transition region 23 is provided between the central melting region 21 of the melt 2 and the terminal region 22, and a second mounting hole 24 is provided on the transition region 23; a first mounting hole 113 is provided on the upper cover housing 11, and a third mounting hole 122 is provided on the lower cover housing 12; during assembly, fasteners pass through the first mounting hole 113, the second mounting hole 24 and the third mounting hole 122 in sequence to fix the melt 2 to the insulating shell 1.

[0077] Specifically, considering that the melt 2 is subjected to huge electrodynamic force and thermal shock when it breaks, it is necessary to ensure its absolute position stability within the shell and to establish a low-resistance, highly reliable electrical connection. Based on this, in this embodiment of the invention, by adding a transition region 22 and adopting a fastening connection method that penetrates the shell, the melt 2 is firmly integrated into the internal structure of the insulating shell 1.

[0078] Specifically, referring to Figure 2, a transition region 23 is provided on both sides of the melt 2 between the central melting region 21 and the terminal region 22. The width of the transition region 23 is between the central melting region 21 and the terminal region 22, which plays the role of smoothing the cross-sectional area, optimizing the current distribution and reducing local hot spots.

[0079] Each transition region 23 is provided with a second mounting hole 24, which is a circular through hole for subsequent mechanical fixing. This symmetrical design not only ensures the balance of the structure, but also ensures the stability of the molten material within the shell and the symmetry of the current path.

[0080] Accordingly, referring to Figures 2 and 4, the width side of the upper cover housing 11 is slightly lower than the height side, forming an engaging step that matches the thickness of the transition region 23, allowing the transition region 23 to be embedded and positioned therein. Simultaneously, two circular first mounting holes 113 are respectively provided on the step surfaces on both sides of this width, their positions precisely aligned with the second mounting holes 24 on the melt 2.

[0081] Referring to Figures 6 and 7, the lower cover housing 12 adopts the same design as the upper cover housing 11, and a third mounting hole 122 is opened at the corresponding position, so that together with the first mounting hole 113 and the second mounting hole 24, a coaxial mounting channel is formed through the upper and lower housings and the melt.

[0082] More specifically, referring to Figure 1, in this embodiment of the invention, rivets 3 are preferably used as fasteners. The three mounting holes are all designed to match the rivet holes. Through the riveting process, the rivets 3 can permanently and firmly fasten the upper cover housing 11, the transition area 23 of the melt 2 and the lower cover housing 12 into one, while forming a connection point with excellent electrical conductivity.

[0083] As can be seen, through the above structural design, the melt 2 is rigidly fixed inside the insulating shell, effectively resisting short-circuit electrodynamic forces, ensuring the stability of the electrical connection and current carrying capacity, while simplifying the overall assembly process and enhancing the mechanical and electrical reliability of the product under harsh working conditions.

[0084] In a preferred embodiment of the present invention, the upper cover housing 11 is provided with a first limiting post 114 and a first limiting hole 115 on both sides, and the lower cover housing 12 is provided with a second limiting post 123 and a second limiting hole 124 on both sides respectively; during assembly, the first limiting post 114 is inserted into the second limiting hole 124, and the second limiting post 123 is inserted into the first limiting hole 115.

[0085] Specifically, considering that before the final permanent fastening with rivets 3 is performed, it is necessary to ensure the precise pre-positioning of the upper cover housing 11 and the lower cover housing 12 in the plane and vertical direction to prevent misalignment, facilitate assembly, and ensure the centering of the internal arc-extinguishing structure, in this embodiment of the invention, a set of complementary column-hole limiting structures is designed on the housing.

[0086] Specifically, referring to Figure 4, two cylindrical first limiting posts 114 are respectively provided on one long side wall inside the upper cover housing 11, and two circular first limiting holes 115 are respectively provided on the opposite long side wall.

[0087] Accordingly, referring to Figures 6 and 7, the design of the long side wall inside the lower cover housing 12 is completely complementary to that of the upper cover housing 11. Specifically, on the side of the upper cover housing 11 where the first limiting hole 115 is provided, two cylindrical second limiting posts 123 are provided, and on the side of the upper cover housing 11 where the first limiting post 114 is provided, two circular second limiting holes 124 are provided.

[0088] During assembly, simply align and fasten the upper cover housing 11 and the lower cover housing 12, and the limiting posts on both sides will automatically insert into the corresponding limiting holes, thereby achieving rapid and accurate pre-positioning of the two, ensuring the regularity of the internal cavity after the housing is closed and the accurate position of each component (especially the composite arc extinguishing core 8).

[0089] This pinhole-fitting limiting design greatly simplifies the assembly process, improves production efficiency, and provides a stable foundation for subsequent riveting and fastening. It is an important auxiliary structure to ensure the consistency and reliability of product structure.

[0090] The above-mentioned fuse can be rigorously tested and verified according to standards such as IEC 60127, UL 248-1, and ISO8820-5. Its specific performance is as follows: First, in the ultimate breaking capacity test at 220VDC and an expected short-circuit current of 50kA, the fuse achieved a full breaking time of ≤4ms, which is significantly improved compared to the typical value of 8-15ms for traditional single quartz sand-filled fuses of the same specification.

[0091] Furthermore, its current limiting characteristics are also excellent. Under a 50kA short-circuit condition, the allowable energy (I²t) is ≤ 50,000A²s, which is only about 1 / 3 to 1 / 4 of that of the traditional solution, thereby greatly reducing the electrical and thermal stress of faults on downstream circuits.

[0092] Secondly, it exhibits excellent insulation performance after disconnection, with an insulation resistance of up to 100 MΩ measured at 220VDC. This fully demonstrates the effectiveness of the double-layer arc-extinguishing structure, ensuring that there are no residual conductive channels after a fault.

[0093] Furthermore, in terms of safety and reliability, the external arc test showed excellent performance: in the 50kA breaking test, the cotton paper placed 50mm from the fuse terminal showed no signs of ignition or burning, and the product did not crack or have any fragments ejected, verifying its excellent safety protection capabilities.

[0094] Furthermore, the product's lifespan and operational consistency are equally outstanding. After 100,000 cycles of rated current (650A) switching, its temperature rise change is <5%; and after 10 cycles of rated breaking capacity (50kA) testing on the same batch of products, its breaking time standard deviation is <0.3ms, demonstrating its long-term stability and high operational reliability.

[0095] Finally, environmental adaptability tests showed that after temperature cycling tests from -40°C to 125°C and high-temperature and high-humidity tests at 85°C / 85%RH, the degradation of all key performance parameters was within 3%. Simultaneously, high-speed video observation at 100,000 frames per second directly confirmed the effectiveness of the dual-layer arc extinguishing mechanism: the arc is forcibly divided and cooled by the ceramic inner cover in the initial stage (0-1ms), and subsequently (1-4ms) the arc plasma is efficiently injected into the dense quartz sand medium and completely extinguished.

[0096] In summary, this invention innovatively introduces a double-layer arc-extinguishing structure composed of a composite arc-extinguishing core, which closely coordinates the first arc-extinguishing layer that actively generates gas and the second arc-extinguishing layer that absorbs gas in a steady state in terms of physical space and functional timing. Combined with a precision inner shell structure made of high-purity ceramic or engineering plastic and a precisely fillable graded arc-extinguishing medium, this invention constructs a high-performance circuit protection scheme that integrates rapid active current limiting, efficient segmented arc extinguishing, and reliable pressure management.

[0097] Compared with the prior art, the present invention has the following significant advancements: performance leap: it achieves an order-of-magnitude improvement in breaking speed and current limiting capability, significantly reduces the total breaking time to the millisecond level, and significantly reduces the allowable energy, reaching an industry-leading breaking performance level.

[0098] Intrinsic safety: Through controllable gas generation and optimized structural design, the internal pressure during the separation process is actively managed and safely released, fundamentally eliminating the phenomena of shell rupture and dangerous arcing, and the safety is revolutionaryly enhanced.

[0099] Process controllability: Its dual-layer synergistic mechanism of "active impact + steady-state absorption" enables dynamic and segmented optimized control of the entire life cycle of arc generation, development, extinction and insulation recovery, making the arc extinguishing process more thorough and the action characteristics more stable and reliable.

[0100] Easy to manufacture: While maintaining the compact shape and basic structure of traditional planar fuses, functional upgrades are made, mainly relying on mature material filling and packaging processes. It has good process inheritance and large-scale production feasibility, providing a practical technical path for the widespread application of high-performance circuit protection.

[0101] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A double-layer arc-extinguishing flat-plate fuse, characterized in that, include: An insulating shell (1); a melt (2), the melt (2) having an integrally formed central melting region (21) and a terminal region (22), the central melting region (21) being located inside the insulating shell (1), and the terminal region (22) being exposed outside the insulating shell (1); a composite arc-extinguishing core (8), disposed inside the insulating shell (1) and surrounding the central melting region (21); wherein, a first arc-extinguishing cavity (81) is formed inside the composite arc-extinguishing core (8), the first arc-extinguishing cavity (81) containing gas-generating material to form a first arc-extinguishing layer; a second arc-extinguishing cavity is formed between the insulating shell (1) and the composite arc-extinguishing core (8), the second arc-extinguishing cavity being filled with an arc-extinguishing medium (82) to form a second arc-extinguishing layer.

2. The double-layer arc-extinguishing flat-plate fuse according to claim 1, characterized in that, The gas-generating material includes one or more of polytetrafluoroethylene, nylon, engineering plastic particles or fibers; the arc-extinguishing medium (82) includes one or more of quartz sand, silicate ceramic particles, alumina microspheres, melamine, sulfur hexafluoride, and epoxy resin.

3. A double-layer arc-extinguishing flat-plate fuse according to claim 1, characterized in that, The insulating housing (1) includes an upper cover housing (11) and a lower cover housing (12), which are fixedly connected by fasteners.

4. A double-layer arc-extinguishing flat-plate fuse according to claim 3, characterized in that, The composite arc-extinguishing core (8) includes: an upper seat (5), which is detachably installed on the inner side of the upper cover shell (11); a lower seat (6), which is detachably installed on the inner side of the lower cover shell (12); and two arc-extinguishing inner shells (7), which are respectively engaged on the upper and lower sides of the central melting area (21) and located between the upper seat (5) and the lower seat (6); the upper seat (5), the lower seat (6) and the two arc-extinguishing inner shells (7) together form the first arc-extinguishing cavity (81).

5. A double-layer arc-extinguishing flat-plate fuse according to claim 4, characterized in that, The upper cover shell (11) has an upper cover groove (111), and the upper seat body (5) has an upper seat body protrusion (51), which engages with the upper cover groove (111); the lower cover shell (12) has a lower cover groove (121), and the lower seat body (6) has a lower seat body protrusion (61), which engages with the lower cover groove (121); the arc-extinguishing inner shell (7) is made of ceramic or engineering plastic, and the arc-extinguishing inner shell (7) has an arc-extinguishing inner cover groove (71), which engages with the central melting area (21).

6. A double-layer arc-extinguishing flat-plate fuse according to claim 4, characterized in that, The upper cover housing (11) is provided with a half hole (112), the upper seat body (5) is provided with an upper seat body through hole surface (52), the lower seat body (6) is provided with a lower seat body through hole surface (62), and the arc-extinguishing inner shell (7) is provided with an arc-extinguishing inner cover through hole surface (72). After assembly, the half hole (112), the upper seat body through hole surface (52), the lower seat body through hole surface (62), and the arc-extinguishing inner cover through hole surface (72) together form a through hole (4) for filling the second arc-extinguishing cavity with the arc-extinguishing medium (82).

7. A double-layer arc-extinguishing flat-plate fuse according to claim 3, characterized in that, The upper cover housing (11) is provided with a first limiting post (114) and a first limiting hole (115) on both sides respectively, and the lower cover housing (12) is provided with a second limiting post (123) and a second limiting hole (124) on both sides respectively; during assembly, the first limiting post (114) is inserted into the second limiting hole (124), and the second limiting post (123) is inserted into the first limiting hole (115).

8. A double-layer arc-extinguishing flat-plate fuse according to claim 3, characterized in that, The melt (2) has a transition region (23) between the central melting area (21) and the terminal area (22), and a second mounting hole (24) is provided on the transition region (23).

9. A double-layer arc-extinguishing flat-plate fuse according to claim 8, characterized in that, The upper cover housing (11) has a first mounting hole (113), and the lower cover housing (12) has a third mounting hole (122). During assembly, fasteners pass through the first mounting hole (113), the second mounting hole (24), and the third mounting hole (122) in sequence to fix the melt (2) to the insulating shell (1).

10. A double-layer arc-extinguishing flat-plate fuse according to claim 1, characterized in that, The melt (2) is a silver or copper alloy strip.

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