Miniature fuse capable of cutting electric arc

Abstract

The invention discloses a small fuse capable of cutting an electric arc. The small fuse comprises an insulating tube, end cap electrodes located at the two ends of the insulating tube and a fuse body located in the insulating tube. Wherein the inner wall of the insulating tube is provided with grooves or bulges, so that a plurality of areas with different depths are formed on the inner wall of the insulating tube, a grid type design of the inner wall of the insulating tube is formed, a plurality of grids are used for rapidly cutting a high-temperature long electric arc generated during high-voltage breaking into a plurality of short electric arcs connected in series, and the total voltage drop of the electric arc is remarkably improved in the cutting process; the current is strongly inhibited.

Description

Technical Field

[0001] This invention relates to the field of miniature fuse technology. Background Technology

[0002] A miniature fuse is an electronic device used to protect circuits, acting as an "automatic switch." When the current in the circuit exceeds a specified value, the fuse melts its fusible element through the heat it generates, thus breaking the circuit and protecting the circuit and electrical equipment from damage. Fuses are widely used in high and low voltage power distribution and control systems, as well as various electrical equipment and household appliances, as short-circuit and overcurrent protection devices. They are simple in structure, easy to use, and feature high breaking capacity, high short-circuit current limiting capability, fast breaking speed, and high reliability.

[0003] Miniature fuses, as core protective components in modern electrical systems, ensure safe circuit operation through precise current control mechanisms. Their core functions can be summarized in the following three aspects:

[0004] 1. Real-time blocking of abnormal current to prevent equipment damage and fire risks.

[0005] When a circuit experiences an overload or short circuit causing the current to exceed a safe threshold, the high-precision fusible element inside the fuse (such as a silver-based alloy or composite material) rapidly melts based on the Joule heating effect, cutting off the current path within milliseconds. This rapid response characteristic not only prevents problems such as insulation burnout and electronic component breakdown caused by overheating of wires, but also effectively prevents arcing sparks generated by short-circuit current, significantly reducing the probability of fire. For example, in the high-voltage battery system of new energy vehicles, miniature fuses can cut off the DC power instantly when the battery pack is short-circuited, preventing thermal runaway and explosion accidents.

[0006] II. Ensuring System Stability and Operational Security

[0007] After cutting off a faulty circuit, a fuse creates a physical isolation point, allowing maintenance personnel to safely troubleshoot faulty equipment and avoid the risks of live operation. Simultaneously, its precise fusing characteristic acts only on the faulty branch, preventing a power outage of the entire power supply system. This makes it particularly suitable for scenarios with extremely high requirements for power continuity, such as data centers and communication base stations. For example, in the DC distribution cabinet of a 5G base station, a surface-mount miniature fuse can isolate a single faulty power module, ensuring continuous power supply to other modules.

[0008] III. Adapting to Miniaturization and Complex Environment Requirements

[0009] Miniature fuses, with ceramic housings or epoxy resin encapsulation, can be reduced to the size of surface-mount components, allowing them to be embedded in high-density integrated circuit boards and providing overcurrent protection for microelectronic products such as smartphones and wearable devices. Their high-temperature resistant, dustproof, and moisture-proof design can withstand harsh environments with frequent vibrations and drastic temperature differences, such as automotive engine compartments and industrial machinery, maintaining stable performance within a range of -55°C to 125°C. For example, in aerospace equipment, high-voltage miniature fuses can continuously protect the circuitry of navigation systems in low-pressure, high-radiation environments.

[0010] Through these multiple protection mechanisms, miniature fuses achieve a balance between miniaturized device protection and complex system reliability while ensuring circuit safety. Currently, high-voltage DC systems in fields such as new energy vehicles, photovoltaics, and energy storage require high-voltage (≥600V) fuses to address short-circuit or overload risks; scenarios such as rail transportation, aerospace, and shipbuilding require fuses that can withstand extreme voltages and are lightweight to meet safety protection needs in complex environments. Furthermore, high-voltage power transmission and distribution, smart grids, and renewable energy grid integration place higher demands on the withstand voltage and arc-extinguishing efficiency of fuses, necessitating miniaturized designs to adapt to compact equipment spaces. Summary of the Invention

[0011] To address the above problems, the purpose of this invention is to provide a miniature fuse capable of cutting electric arcs, thereby improving the withstand voltage and breaking capacity of the miniature fuse by efficiently extinguishing high-current electric arcs.

[0012] To achieve the above-mentioned objectives, the miniature fuse capable of cutting electric arcs of the present invention can adopt the following technical solution:

[0013] A small arc-cutting fuse includes an insulating tube, end cap electrodes at both ends of the insulating tube, and a fusible element located inside the insulating tube and connected to the end cap electrodes respectively. At least one inner wall of the insulating tube is provided with grooves or protrusions to form several regions of varying depths on the inner wall of the insulating tube.

[0014] Furthermore, the melt is a filamentous melt with the same diameter throughout.

[0015] Furthermore, the melt includes a plurality of wide segments and a plurality of narrow segments connected sequentially along the length of the melt, with each narrow segment connected between two adjacent wide segments; at least one insulating tube has a plurality of grooves on its inner wall, each groove corresponding to a narrow segment, such that the projection of the narrow segment on the inner wall of the insulating tube is at least partially located within the range of the corresponding groove.

[0016] Furthermore, the insulating tube has a square cross-section, and both inner walls facing each other are provided with grooves. The grooves on the two inner walls are arranged facing each other and are the same size.

[0017] Furthermore, the insulating tube is filled with an arc-quenching material that encapsulates the molten material, and the arc-quenching material completely fills the groove.

[0018] Furthermore, the cross-section of the groove is U-shaped, V-shaped, or square.

[0019] Furthermore, the melt is a filamentous melt with the same diameter throughout, and at least one protrusion is provided on the inner wall of at least one insulating tube.

[0020] Furthermore, the melt includes a plurality of wide segments and a plurality of narrow segments connected sequentially along the length of the melt, with each narrow segment connected between two adjacent wide segments; at least one insulating tube has a plurality of protrusions on its inner wall, each protrusion corresponding to a narrow segment, such that the projection of the narrow segment on the inner wall of the insulating tube is at least partially located within the range of the corresponding protrusion.

[0021] Furthermore, the insulating tube has a square cross-section, and both inner walls facing each other in the insulating tube are provided with protrusions. The protrusions on the two inner walls are arranged facing each other and are the same size.

[0022] Furthermore, the insulating tube is filled with an arc-quenching material that encapsulates the molten material, and the arc-quenching material completely fills the cavity.

[0023] Beneficial Effects: Compared with existing technologies, the technical solution of this invention uses grooves or protrusions to form several regions of varying depths on the inner wall of the insulating tube, creating a grid-like design. Multiple grids rapidly cut the high-temperature, long electric arc generated during high-voltage interruption into multiple short arcs connected in series. This segmentation process significantly increases the total voltage drop of the arc and strongly suppresses current. If arc-extinguishing materials are further added, the thermal conductivity of the grids and the properties of the arc-extinguishing materials quickly absorb the heat of the arc, rapidly cooling the high-temperature ionized gas. Under this dual effect, by limiting current through voltage rise and accelerating deionization through physical cooling, the arc is difficult to reignite after the current crosses zero, thus efficiently and reliably extinguishing high-current arcs in a very short time, achieving high breaking capacity, and effectively limiting the damage of arc energy to the system. Attached Figure Description

[0024] Figure 1 This is a three-dimensional perspective view of the arc-cutting miniature fuse of Embodiment 1;

[0025] Figure 2 This is a schematic diagram showing the relative positions of the fuse wire and the groove in the small arc-cutting fuse of Embodiment 1;

[0026] Figure 3 This is a three-dimensional perspective view of the arc-cutting miniature fuse of Embodiment 2;

[0027] Figure 4 This is a schematic diagram showing the relative positions of the fuse wire and the groove in the small arc-cutting fuse of Embodiment 2.

[0028] Figure 5 This is a perspective view of the arc-cutting miniature fuse of Embodiment 3.

[0029] Figure 6 This is a half-sectional schematic diagram of a small arc-cutting fuse according to Embodiment 3.

[0030] Figure 7 This is a perspective view of a small arc-cutting fuse according to Embodiment 4.

[0031] Figure 8 This is a half-sectional schematic diagram of a small arc-cutting fuse according to Embodiment 4. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] Please combine Figure 1 and Figure 2 As shown, this embodiment discloses a small arc-cutting fuse, including an insulating tube 1, end cap electrodes 2 located at both ends of the insulating tube 1, and a molten material 3 located inside the insulating tube 1 and connected to the end cap electrodes 2 respectively. The molten material 3 is a filamentous molten material with a constant diameter. The inner wall of the insulating tube 1 is recessed with grooves 4. In this embodiment, the insulating tube 1 has a square cross-section, and both facing inner walls of the insulating tube 1 are provided with grooves 4. These grooves 4 create a grid structure on the inner wall of the insulating tube 1.

[0035] The grid design formed by this groove mainly serves the following purposes:

[0036] 1. Physical arc segmentation: Forced path interruption. The groove inside the insulating tube forms a physical barrier (grid-like structure) in the melting area of ​​the molten material. When the molten material melts and vaporizes under overcurrent, what is initially formed is a continuous long arc that runs through the entire melting area. As it expands and enters the groove, it will inevitably be cut and blocked by the steps formed at the edge of the groove. This is equivalent to forcibly dividing the original long arc into multiple short arcs connected in series.

[0037] 2. Series Short Arc Effect (Increased Arc Voltage): Each segmented short arc is an independent arc segment, and each short arc segment has its own cathode voltage drop region and anode voltage drop region (these are the main contributors to the voltage across the arc, almost unrelated to the current). When multiple short arcs are connected in series, the total arc voltage is equal to the sum of the voltage drops of all the short arc segments.

[0038] Simplified explanation of the formula: Varc total ≈ N*(Vcathode + Vanode) + E*Ltotal

[0039] Note: N: Number of short arc segments

[0040] Vcathode / V_anode: Near-polar voltage drop of each segment.

[0041] E: Electric field strength of the arc column

[0042] Ltotal: Total arc length, but near-electrode voltage drop is dominant.

[0043] Even if the total arc length Ltotal remains unchanged (or even increases slightly), increasing the number of series segments N can significantly increase the total arc voltage, Varc total. For example, dividing a long arc into 10 short arcs connected in series can increase the total voltage several times.

[0044] Ohm's Law effect (suppressing current):

[0045] According to Ohm's law for circuits: I = (Vsource - Varc) / Rcircuit), the loop current I is determined by the power supply voltage Vsource and the loop impedance (mainly the arc resistance Rarc).

[0046] The sharp increase in the total arc voltage Varc total is equivalent to having a large reverse voltage source connected in series in the fault circuit, which directly cancels out a large part of the power supply voltage Vsource. The current I in the fault circuit is forced to decrease rapidly, and the decrease in current means a reduction in the arc input energy.

[0047] 3. Forced Cooling and Surface Effect (Accelerated Deionization): The heat dissipation area increases dramatically, and the insulating tube wall of each groove becomes a heat dissipation surface for the electric arc. After segmentation, the contact area between the electric arc and the insulating tube increases significantly. In this embodiment, high-efficiency thermally conductive ceramics (such as 95% alumina) can be selected. This material has excellent thermal conductivity and can quickly conduct away the huge heat generated by the electric arc. Surface cooling and deionization: When the high-temperature electric arc plasma (metal vapor + ionized gas) comes into contact with the relatively low-temperature ceramic wall, the temperature drops sharply, the degree of thermal ionization decreases (particle kinetic energy decreases, recombination probability increases), charged particles (electrons, ions) directly collide with the wall and recombine, and metal vapor rapidly condenses and deposits on the ceramic surface, reducing the source of conductive particles in the arc channel. Limiting the arc diameter: The narrow space of the groove restricts the expansion of the electric arc plasma, increases its density, which is conducive to collisions and recombination between particles, and causes the resistivity of each short arc segment to increase sharply (cooling reduces charge carriers), further suppressing the current and accelerating the extinction of the arc.

[0048] 4. Electrodynamic effect (assisted segmentation): At the moment of segmentation, a huge short-circuit current flows through the arc. Under the action of the arc's own magnetic field, the current generates an electrodynamic force (Lorentz force). This electrodynamic force tends to push the (relatively soft and movable) arc plasma toward the wall formed by the ceramic groove, accelerating the contact and segmentation process between the arc and the wall.

[0049] 5. Synergy with arc-quenching materials (such as silica sand): For high-breaking capacity fuses, silica sand filler is used to fill the inside of the ceramic tube. The groove structure can work synergistically with silica sand: the grooves divide the arc, and the silica sand fills the gaps in the grooves, providing additional cooling surface area and mechanical compression / confining effect, further accelerating the cooling and deionization of the arc.

[0050] Therefore, the advantages of the arc-cutting miniature fuse in this embodiment compared to traditional miniature fuses are as follows:

[0051] 1. Improved heat dissipation capacity: Traditional small fuses rely solely on the surface of the casing for heat dissipation, resulting in high temperature rise during continuous operation and easy material aging. This invention's grid design increases the heat dissipation area and quickly dissipates heat.

[0052] 2. The arc extinguishing efficiency is improved. Traditional small fuses rely on a single chamber filled with arc extinguishing material for arc extinguishing. The arc is prone to be concentrated in a local area and the shell is easily eroded by the high temperature of the arc. The grid design breaks the arc into multiple short arc segments, and the arc extinguishing medium is filled more evenly, which greatly improves the success rate of breaking.

[0053] 3. Overcurrent protection accuracy is improved. Traditional small fuses have a large fusing threshold error, which can easily lead to insufficient protection or malfunction. The grid design structure can reduce the fusing threshold error and improve the overcurrent protection accuracy by controlling the thermal interaction between the groove and the fusible element.

[0054] In addition to improving the withstand voltage and breaking capacity of miniature fuses, this technical solution also provides other functions, including enhanced vibration and shock resistance. Compared to the rigid connection between the fusible element and electrode in traditional miniature fuses, which is prone to breakage in 10-2000Hz vibration environments, the grid design in this embodiment, through the use of arc-shaped transitions at the four corners of the groove and the superimposed toughening coating on the inner wall of the insulating tube, disperses and buffers vibration energy through the insulating tube body, reducing the amplitude between the fusible element and the electrode fixed on the ceramic tube. This significantly reduces the failure rate of the internal and external electrode connection caused by vibration, thereby improving the product's vibration and shock resistance.

[0055] Additionally, optionally, a self-healing nanomaterial coating (such as a toughened zirconia resin coating) can be impregnated or coated on the surface of the insulating tube grid. When the grid is subjected to arc erosion or physical damage, the nanoparticles in the coating will automatically gather and recombine at the damaged location, filling the tiny cracks and gaps, restoring the physical and electrical insulation properties of the grid, extending the service life of the insulating tube (especially in high temperature and high stress scenarios) and resisting the high-energy impact at the moment of breakage.

[0056] Example 2

[0057] Please combine Figure 3 and Figure 4 As shown, this embodiment discloses a small arc-cutting fuse, including an insulating tube 1, end cap electrodes 2 located at both ends of the insulating tube 1, and a fusible element 3 located inside the insulating tube 1 and connected to the end cap electrodes 2 respectively. The fusible element 3 includes several wide segments 5 and several narrow segments 6 connected sequentially along its length, with each narrow segment 6 connected between two adjacent wide segments 5. The inner wall of the insulating tube 1 is provided with several grooves 4, each groove 4 corresponding to a narrow segment 6, such that the projection of the narrow segment 6 on the inner wall of the insulating tube is at least partially within the range of the corresponding groove 4. These grooves 4 form a grid structure on the inner wall of the insulating tube 1. In this embodiment, under the same material, the resistance of the narrow segment 6 is higher than that of the wide segment 5. Therefore, when the fusible element 3 melts, the narrow segment 6 melts first, and the narrow segment 6 closer to the middle of the fusible element melts more easily. Therefore, in this embodiment, grooves 4 are correspondingly provided on three narrow segments 6 near the middle of the fusible element, so that the continuous long arc generated at the melting point can first enter the area of ​​the groove 4. The number, depth, width, and cross-sectional shape (U-shaped, V-shaped, square, etc.) of the grooves 4 can all be selected through experiments to set groove parameters that meet the requirements of different fuses. Furthermore, in this embodiment, grooves 4 are provided on both inner walls of the insulating tube 1 that face each other, and the grooves 4 on the two inner walls are arranged facing each other and are the same size.

[0058] Similar to the main function of the grid design formed by the grooves described in Embodiment 1, the multiple grooves 4 in this Embodiment 2 are also for dividing the generated long electric arc. Since there are multiple grooves 4, the electric arc can be divided into multiple short arcs to improve the withstand voltage and breaking capacity of the miniature fuse, and improve the heat dissipation capacity of the high heat generated by the fuse.

[0059] Example 3

[0060] Please combine Figure 5 and Figure 6As shown, the miniature fuse provided in this embodiment has a structure that is largely the same as that in Embodiment 1. The difference is that the groove in Embodiment 1 is removed and replaced with at least one protrusion 7 on the inner wall of the insulating tube. The protrusion is also designed to form a grid-like structure. When the filamentary fuse 3 melts, the long arc is cut into several short arcs by the side edges of the protrusion 7.

[0061] Example 4

[0062] The miniature fuse provided in this embodiment has a structure largely the same as that in Embodiment 2. The difference is that the groove in Embodiment 1 is removed, and instead, several protrusions 7 are provided on the inner wall of the insulating tube. A cavity is formed between two adjacent protrusions 7. Each protrusion 7 corresponds to a narrow segment 6, such that the projection of the narrow segment 6 on the inner wall of the insulating tube is at least partially within the range of the corresponding protrusion 7. The protrusions 7 are also provided to form a grid-like structure. When the narrow segment of the fuse melts, the long arc is cut into several short arcs by the side edges of the protrusions 7.

Claims

1. A miniature fuse capable of cutting an electric arc, comprising an insulating tube, end cap electrodes located at both ends of the insulating tube, and a fusible element located inside the insulating tube and connected to the end cap electrodes respectively, characterized in that: At least one insulating tube has grooves or protrusions on its inner wall, which creates several areas of varying depths on the inner wall of the insulating tube.

2. The miniature fuse capable of cutting electric arcs as described in claim 1, characterized in that, The melt is a filamentous melt with the same diameter throughout.

3. The miniature fuse capable of cutting electric arcs as described in claim 1, characterized in that, The melt includes several wide segments and several narrow segments connected sequentially along the length of the melt, with each narrow segment connected between two adjacent wide segments; at least one insulating tube has several grooves on its inner wall, each groove corresponding to a narrow segment, such that the projection of the narrow segment on the inner wall of the insulating tube is at least partially located within the range of the corresponding groove.

4. The miniature arc-cutting fuse as described in claim 2 or 3, characterized in that, The insulating tube has a square cross-section, and two inner walls facing each other are provided with grooves. The grooves on the two inner walls are arranged facing each other and are the same size.

5. The miniature fuse capable of cutting electric arcs as described in claim 4, characterized in that, The insulating tube is filled with an arc-quenching material that encapsulates the molten material, and the arc-quenching material completely fills the groove.

6. The miniature arc-cutting fuse as described in claim 2 or 3, characterized in that, The cross-section of the groove is U-shaped, V-shaped, or square.

7. The miniature fuse capable of cutting electric arcs as described in claim 1, characterized in that, The melt is a filamentous melt with the same diameter throughout, and at least one protrusion is provided on the inner wall of at least one insulating tube.

8. The miniature fuse capable of cutting electric arcs as described in claim 1, characterized in that, The melt includes several wide segments and several narrow segments connected sequentially along the length of the melt, with each narrow segment connected between two adjacent wide segments; at least one insulating tube has several protrusions on its inner wall, each protrusion corresponding to a narrow segment, such that the projection of the narrow segment on the inner wall of the insulating tube is at least partially located within the range of the corresponding protrusion.

9. The miniature fuse capable of cutting electric arc as described in claim 7 or 8, characterized in that, The insulating tube has a square cross-section, and both inner walls facing each other are provided with protrusions. The protrusions on the two inner walls are arranged facing each other and are the same size.

10. The miniature fuse capable of cutting electric arcs as described in claim 9, characterized in that, The insulating tube is filled with an arc-quenching material that encapsulates the molten material, and the arc-quenching material completely fills the cavity.

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