A surface mount fuse

Abstract

This invention relates to the field of fuse technology, specifically a surface-mount fuse, comprising an insulating shell and a molten metal element. The insulating shell has side cavities and an inner platform. The side cavities are located at both ends of the inner platform. A narrow cavity communicating with the side cavities is located within the inner platform, and the cross-sectional area of ​​the side cavities is larger than that of the narrow cavity. The molten metal element is disposed through the narrow cavity, with both ends of the molten metal element positioned within the side cavities. The surface-mount fuse of this invention has advantages such as high breaking capacity, lead-free design, simple manufacturing process, and low cost. The design of the insulating shell in this invention incorporates four arc-extinguishing mechanisms: the rapid cooling effect of the high thermal conductivity of quartz sand on the electric arc; increased mechanical strength and impact resistance due to the thicker wall in the middle of the shell; arc-extinguishing effect of arc-extinguishing gas generated by the high-temperature ablation of the shell surface; and increased cross-sectional area of ​​the inner holes at both ends of the shell to provide pressure relief space. These mechanisms improve the breaking capacity of the product.

Description

Technical Field

[0001] This invention relates to the field of fuse technology, specifically to a surface-mount fuse. Background Technology

[0002] A fuse mainly consists of a fusible element and an insulator that supports or protects the fusible element. The fusible element is made of a low-melting-point metal material or paste, using metal wire or sheet electrodes, and is connected in series in the protected circuit. When the circuit or equipment in the circuit is overloaded or malfunctions, the fusible element heats up and melts instantaneously, thus cutting off the circuit and protecting the circuit or equipment. With the miniaturization of fuses, the safety of the fusible element during breaking has gradually become one of the key factors to consider in product applications. At the moment of breaking a short circuit due to excessive fault current, a powerful electric arc is generated on the fusible element. If there is no material nearby to extinguish this arc, the fuse may burn or even explode. This could damage other valuable components in the circuit, or even cause a fire due to the arc igniting, endangering personal safety.

[0003] In addition to generating a large amount of heat energy, the melt also experiences two forms of pressure during the breaking process: the pulse-like explosion pressure generated at the moment of melt vaporization and arc ignition, and the arc pressure generated throughout the entire arcing process. Conventional arc-extinguishing materials can generally reduce the impact of heat energy generated during melt breaking by undergoing physical and chemical changes such as pyrolysis, melting, evaporation, sublimation, and erosion under high-temperature heat flow, causing mass loss on the material surface. However, due to the presence of high temperatures, conventional arc-extinguishing materials such as quartz sand, silica gel, thermosetting resins, and glass coatings often lack the elastic buffering capacity against explosion pressure. The pyrolysis gases generated by the arc-extinguishing components can further increase the internal pressure of the arc-extinguishing device, thus easily causing fuse failure during continuous arcing. Summary of the Invention

[0004] To address the above shortcomings, the purpose of this invention is to provide a surface-mount fuse.

[0005] This invention provides the following technical solution:

[0006] A surface-mount fuse includes an insulating shell and a molten metal element. The insulating shell has a side cavity and an inner platform. The side cavity is located at both ends of the inner platform. The inner platform has a narrow cavity communicating with the side cavity. The cross-sectional area of ​​the side cavity is larger than the cross-sectional area of ​​the narrow cavity.

[0007] The molten metal is disposed throughout the narrow cavity, with both ends of the molten metal placed in the side cavities.

[0008] As a preferred technical solution for surface-mount fuses, the inner platform and the insulating shell are integrally formed.

[0009] As a preferred technical solution for surface-mount fuses, the inner platform is embedded in the insulating housing and welded in place.

[0010] As a preferred technical solution for surface-mount fuses, the cross-sectional shape of the side cavity is circular or square.

[0011] As a preferred technical solution for surface-mount fuses, the cross-sectional shape of the narrow cavity is circular or square.

[0012] As a preferred technical solution for surface-mount fuses, the narrow cavity and side cavity are filled with arc-extinguishing material.

[0013] As a preferred technical solution for a surface-mount fuse, the insulating housing is provided with end electrode caps at both ends, the outer side of the insulating housing is provided with a protrusion, the inner wall of the end electrode cap is provided with a cavity, and the protrusion is embedded in the cavity.

[0014] As a preferred technical solution for a surface-mount fuse, the end electrode cap includes an inner cap and an outer cap, the cavity is disposed on the inner cap, the inner cap is fitted onto the end of the insulating shell, and the outer cap is fitted onto the outside of the inner cap.

[0015] As a preferred technical solution for a surface-mount fuse, the end electrode cap is provided with solder, and the solder connects the inner cap and the end of the molten metal.

[0016] As a preferred technical solution for surface-mount fuses, the insulating shell is injection molded from a high-temperature resistant thermosetting resin material, and 20wt% to 40wt% of glass fiber is added to the resin material; the arc-extinguishing material is 80-120 mesh quartz sand.

[0017] The beneficial effects of this invention are as follows: The surface-mount fuse of this invention has advantages such as high breaking capacity, lead-free design, simple manufacturing process, and low cost. The design of the insulating shell in the surface-mount fuse of this invention incorporates four arc-extinguishing mechanisms: the rapid cooling effect of the high thermal conductivity of quartz sand on the electric arc; the increased mechanical strength and impact resistance due to the thicker wall in the middle of the shell; the arc-extinguishing effect of arc-extinguishing gas generated by the high-temperature ablation of the shell surface; and the increased cross-sectional area of ​​the inner holes at both ends of the shell to provide pressure relief space. These mechanisms improve the breaking capacity of the product. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0019] Figure 1 This is a schematic cross-sectional view of the device of the present invention;

[0020] Figure 2 This is a cross-sectional structural diagram of the separate design of the inner platform and the insulating shell in this invention;

[0021] Figure 3 This is a schematic diagram of a side cavity in the insulating shell of the present invention;

[0022] Figure 4 This is another structural schematic diagram of the side cavity in the insulating shell of the present invention;

[0023] Figure 5 This is a schematic diagram of the end electrode cap in this invention;

[0024] In the figure: 1. Insulating shell, 2. Molten metal, 11. Side cavity, 12. Inner platform, 13. Narrow cavity, 14. Arc extinguishing material, 3. End electrode cap, 15. Protrusion, 31. Concave cavity, 33. Inner cap, 34. Outer cap, 32. Solder. Detailed Implementation

[0025] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of one or more embodiments of the present invention.

[0026] It should be noted that the steps of the corresponding methods in other embodiments are not necessarily performed in the order shown and described in this invention. In some other embodiments, the methods may include more or fewer steps than those described in this invention. Furthermore, a single step described in this invention may be broken down into multiple steps in other embodiments; and multiple steps described in this invention may be combined into a single step in other embodiments.

[0027] Please refer to Figures 1 to 5 As shown, a surface-mount fuse includes an insulating housing 1 and a molten metal 2. The insulating housing 1 has a side cavity 11 and an inner platform 12. The side cavity 11 is located at both ends of the inner platform 12. The inner platform 12 has a narrow cavity 13 that communicates with the side cavity 11. The cross-sectional area of ​​the side cavity 11 is larger than the cross-sectional area of ​​the narrow cavity 13. The molten metal 2 is disposed through the narrow cavity 13, and both ends of the molten metal 2 are placed in the side cavity 11.

[0028] It should be noted that the insulating shell 1 is injection molded from a high-temperature resistant thermosetting resin material, including one or more of polyphenylene sulfide, polyimide, polyether ether ketone, and polysulfone. 20wt% to 40wt% of glass fiber is added to the resin material to improve the mechanical strength of the insulating shell and prevent the insulating shell from being damaged by the explosive pressure impact generated when the fuse product breaks.

[0029] Furthermore, the narrow cavity 13 and side cavity 11 of the insulating shell 1 form a constricted design with large ends and small middle. Under the premise of ensuring that the middle part of the insulating shell 1 has sufficient wall thickness to improve its mechanical strength and can generate gas under the action of high temperature electric arc to extinguish the electric arc, the space of the side cavity 11 at both ends of the insulating shell 1 is enlarged to relieve or disperse the impact of the explosion pressure generated by the melt breaking on the end electrode caps 3 at both ends, and to prevent the risk of cap removal.

[0030] Furthermore, the molten metal 2 extends in the side cavity 11.

[0031] The molten metal 2 is a metal wire or sheet made of silver, copper or their alloys, and may optionally be coated with a surface coating such as silver or tin.

[0032] Reference Figure 1 The inner platform 12 and the insulating shell 1 are integrally formed.

[0033] Reference Figure 2 The inner platform 12 is embedded in the insulating shell 1 and welded in place.

[0034] Reference Figure 3 and Figure 4 The cross-sectional shape of the side cavity 11 is circular or square; the cross-sectional shape of the narrow cavity 13 is circular or square.

[0035] The narrow cavity 13 and the side cavity 11 are filled with arc-extinguishing material 14.

[0036] The arc-extinguishing material 14 is preferably made of quartz sand with a mesh size of 80 to 120, so that it can be easily filled even when the product volume is small.

[0037] Furthermore, the insulating shell 1 is provided with end electrode caps 3 at both ends, and the outer side of the insulating shell 1 is provided with protrusions 15. The inner wall of the end electrode cap 3 is provided with a cavity 31, and the protrusions 15 are embedded in the cavity 31. The end electrode cap 3 includes an inner cap 33 and an outer cap 34. The cavity 31 is provided on the inner cap 33. The inner cap 33 is fitted onto the end of the insulating shell 1, and the outer cap 34 is fitted onto the outside of the inner cap 33.

[0038] The end electrode cap 3 is divided into two parts: an inner cap 33 and an outer cap 34. The inner cap 33 is tightly bonded to the end of the insulating shell 1 by mechanical pressing, and the outer cap 34 is installed on the outside of the inner cap 33 by mechanical pressing, so as to ensure good electrical connection between the inner and outer caps and the molten metal.

[0039] Furthermore, a protrusion can be formed at a certain position on two opposite surfaces or four sides of the insulating shell 1. Correspondingly, a cavity 31 is formed at the corresponding position of the end electrode cap 3. When the inner cap 33 is installed, the protrusion 15 is pressed into the cavity 31, which can greatly improve the bonding strength of the end electrode cap 3 of the product.

[0040] The end electrode cap 3 is provided with solder 32, which connects the inner cap 33 and the end of the molten metal 2.

[0041] Solder 32 is preferably a lead-free solder with components such as tin-copper or tin-silver-copper to meet RoHS requirements.

[0042] The above are merely preferred embodiments of one or more embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of the present invention should be included within the protection scope of one or more embodiments of the present invention.

Claims

1. A surface-mount fuse, characterized in that, It includes an insulating shell (1) and a molten metal (2). The insulating shell (1) is provided with a side cavity (11) and an inner platform (12). The side cavity (11) is located at both ends of the inner platform (12). The inner platform (12) is provided with a narrow cavity (13). The narrow cavity (13) is connected to the side cavity (11). The cross-sectional area of ​​the side cavity (11) is larger than the cross-sectional area of ​​the narrow cavity (13). The molten metal (2) is disposed through the narrow cavity (13), and both ends of the molten metal (2) are placed in the side cavities (11); The insulating shell (1) is provided with end electrode caps (3) at both ends, and the outer side of the insulating shell (1) is provided with protrusions (15). The inner wall of the end electrode caps (3) is provided with cavities (31), and the protrusions (15) are embedded in the cavities (31). The end electrode cap (3) includes an inner cap (33) and an outer cap (34). The cavity (31) is disposed on the inner cap (33). The inner cap (33) is fitted onto the end of the insulating shell (1), and the outer cap (34) is fitted onto the outside of the inner cap (33). The end electrode cap (3) is provided with solder (32), which connects the inner cap (33) and the end of the molten metal (2); The narrow cavity (13) and the side cavity (11) are filled with arc-extinguishing material (14). The insulating shell is injection molded from a high-temperature resistant thermosetting resin material, to which 20wt%~40wt% of glass fiber is added. The arc-extinguishing material is quartz sand of 80-120 mesh. The solder (32) is tin-copper or tin-silver-copper.

2. The surface-mount fuse according to claim 1, characterized in that, The inner platform (12) is integrally formed with the insulating shell (1).

3. The surface-mount fuse according to claim 1, characterized in that, The inner platform (12) is embedded in the insulating shell (1) and welded in place.

4. The surface-mount fuse according to claim 2 or 3, characterized in that, The cross-sectional shape of the side cavity (11) is circular or square.

5. The surface-mount fuse according to claim 4, characterized in that, The cross-sectional shape of the narrow cavity (13) is circular or square.

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