Fuse capable of breaking circuit at low-rate overcurrent

Abstract

The utility model relates to the technical field of fuses, in particular to a fuse capable of breaking a circuit at low-rate overcurrent. The fuse comprises a first electrode, a second electrode, a deformable conductive piece, a first melt and an elastic tripping device, a first end of the conductive piece is electrically connected with the first electrode, a second end of the conductive piece is electrically connected with a first end of the first melt through welding and fixing of low-melting-point metal, and the elastic tripping device is electrically connected with the conductive piece. The second end of the first melt is electrically connected with the second electrode, and when the low-melting-point metal is melted and softened under the action of overload current, the conductive piece deforms under the action of the elastic tripping device, so that the second end of the conductive piece is far away from the first end of the first melt. According to the utility model, under the condition of low-rate overload current, the fuse can timely disconnect a circuit, the risk of burnout of a device is avoided, external triggering is not needed, the structure is simple, and the realization is easy.

Description

Technical Field

[0001] The utility model belongs to the technical field of fuses, and in particular relates to a fuse capable of disconnecting a circuit at a low overcurrent rate. Background Art

[0002] The battery system of the energy storage system generally uses a lithium battery pack with high energy density. When a high energy density lithium battery short-circuits, it is very easy to cause a major safety accident. As the application of energy storage systems becomes more and more extensive, manufacturers are paying more and more attention to the safety of energy storage systems.

[0003] In order to avoid safety accidents in energy storage systems, the prior art generally sets corresponding fuses in the battery packs and each battery cluster in the energy storage system to protect the circuit. Generally, in order to avoid premature failure of the fuse, a certain margin is considered when selecting the fuse. Generally, the rated current of the selected fuse will be 1.5 to 2.5 times the maximum charge and discharge current of the normal battery cluster. For fuses with partial range disconnection, the safe disconnection current is generally more than 5 times the rated current of the fuse. Even for fuses with full range disconnection capacity, the minimum current for safe disconnection must be 2 times its rated current. In this case, when the battery cluster has a low-rate overload greater than the rated current of the fuse (such as less than 2 times the rated current), the fuse often cannot disconnect the circuit in time, resulting in safety accidents such as burning of the energy storage system, causing serious property losses. Summary of the invention

[0004] The utility model aims to provide a fuse capable of breaking a circuit at a low overcurrent rate to solve the above-mentioned technical problems.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a fuse that can interrupt a circuit at a low-rate overcurrent, comprising a first electrode, a second electrode, a deformable conductive member, a first fuse and an elastic release device, wherein the first end of the conductive member is electrically connected to the first electrode, the second end of the conductive member is electrically connected to the first end of the first fuse by welding and fixing with a low-melting-point metal, and the second end of the first fuse is electrically connected to the second electrode. When the low-melting-point metal melts and softens under the action of an overload current, the conductive member is deformed under the action of the elastic release device to make the second end of the conductive member move away from the first end of the first fuse.

[0006] Furthermore, the conductive element is a flexible conductive element.

[0007] Furthermore, the conductive member is a braided copper wire.

[0008] Furthermore, the elastic release device is implemented by a spring, and one end of the spring is fixedly connected to the second end of the conductive member.

[0009] Furthermore, it also includes a first shell, the conductive member and the first melt are arranged in the cavity of the first shell, and the first electrode and the second electrode extend out of the first shell.

[0010] Furthermore, a boss is provided in the cavity of the first shell, and the first end of the first melt is fixed on the boss.

[0011] Furthermore, it also includes a second melt, which is arranged in parallel with the conductive member and the first melt.

[0012] Furthermore, the current carrying capacity of the second melt is smaller than the current carrying capacity of the first melt.

[0013] Furthermore, it also includes a second shell, a third electrode and a fourth electrode. The second melt is arranged in the cavity of the second shell, and the two ends are electrically connected to the third electrode and the fourth electrode respectively. The third electrode and the fourth electrode extend out of the second shell, and the third electrode and the fourth electrode are electrically connected to the first electrode and the second electrode respectively.

[0014] Furthermore, the first melt and the second melt are both sheet-like structures, and a plurality of narrow necks are provided on the first melt and the second melt, and the plurality of narrow necks are spaced apart along the two end directions of the first melt and the second melt.

[0015] Furthermore, there are multiple first melts, and the multiple first melts are arranged in parallel.

[0016] Furthermore, the first melt and the second melt are surrounded by arc extinguishing medium.

[0017] Beneficial technical effects of the utility model:

[0018] The utility model provides a deformable conductive part and an elastic release device, wherein the conductive part and the first melt are fixed in series by welding with a low-melting-point metal. When a small overload current appears in the circuit, the low-melting-point metal melts and softens under the action of the small overload current, and the conductive part deforms under the action of the elastic release device to separate the conductive part from the first melt, thereby achieving the effect that the fuse can disconnect the circuit in time under the condition of a low-rate overload; when a large short-circuit current appears in the circuit, the current flows through the melt, and the melt melts and disconnects to cut off the circuit in time, thereby having the function of timely disconnection in the case of a small overload current and a large short-circuit current, thereby avoiding the risk of burning the device and avoiding property loss, and no external trigger is required, the structure is simple, and it is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use 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 ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a structural diagram of the first embodiment of the utility model;

[0021] Figure 2 This is a partial exploded view of the first embodiment of the utility model in which the arc extinguishing medium is omitted;

[0022] Figure 3 It is a partial structural diagram of the first embodiment of the utility model;

[0023] Figure 4 This is a cross-sectional view of the first embodiment of the utility model with the arc extinguishing medium omitted;

[0024] Figure 5 This is a structural diagram of the second embodiment of the present utility model;

[0025] Figure 6 This is a partial exploded view of the second embodiment of the utility model in which the arc extinguishing medium is omitted;

[0026] Figure 7 It is a partial exploded view of another perspective of the second embodiment of the utility model in which the arc extinguishing medium is omitted;

[0027] Figure 8 This is a cross-sectional view of the second embodiment of the present invention in which the arc extinguishing medium is omitted. DETAILED DESCRIPTION

[0028] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0029] The utility model is now further described in conjunction with the accompanying drawings and specific implementation methods.

[0030] Embodiment 1

[0031] like Figure 1-4 As shown, a fuse capable of breaking a circuit at a low overcurrent rate comprises a first electrode 1, a second electrode 2, a deformable conductive member 3, a first fuse 4, an elastic tripping device 5 and a first housing 6. The first end (i.e. Figure 2-4 The left end of the conductive member 3 is electrically connected to the first electrode 1, and the second end of the conductive member 3 (i.e. Figure 2-4 The right end of the first melt 4 (i.e. Figure 2-4 The left end in the figure) is electrically connected by welding and fixing with a low melting point metal 7, and the second end of the first melt 3 (i.e. Figure 2-4 The right end in the figure is electrically connected to the second electrode 2, and the elastic release device 5 is used to drive the conductive member 3 to deform when the low-melting-point metal 7 melts and softens under the action of the overload current, so that the second end of the conductive member 3 is away from the first end of the first melt 4.

[0032] In this specific embodiment, the first shell 6 is a rectangular parallelepiped structure, which is simple and compact, but is not limited thereto. In some embodiments, the structure of the first shell 6 can be set according to actual needs.

[0033] Specifically, in this embodiment, the first housing 6 includes an open housing body 61 and a cover plate 62, and the cover plate 62 is detachably covered on the opening of the housing body 61, which is easy to assemble and maintain. The cover plate 62 and the housing body 61 are fixed by screws 63, which has good stability and is easy to disassemble and assemble, but it is not limited to this. In some embodiments, the cover plate 62 and the housing body 61 can also be fixed by other fixing structures.

[0034] The first shell 6 can be made of high-strength pressure-resistant insulating materials such as melamine and ceramics. The first electrode 1, the second electrode 2, the deformable conductive member 3, the first melt 4 and the elastic release device 5 are arranged in the cavity of the first shell 6, and the first electrode 1 and the second electrode 2 extend to the left and right side walls of the first shell 6 along the length direction (with the first electrode 1 extending to the left and right side walls of the first shell 6 along the length direction). Figure 1-4 as a direction reference) to facilitate electrical connection in subsequent use.

[0035] In this specific embodiment, the first electrode 1 and the second electrode 2 are both L-shaped sheet structures, and the outer ends of the first electrode 1 and the second electrode 2 are respectively located outside the left and right side walls of the first shell 6, as connecting electrodes between the fuse and the external circuit, and the inner ends of the first electrode 1 and the second electrode 2 are respectively located inside the left and right side walls of the first shell 6, and the first electrode 1 and the second electrode 2 are both locked and fixed to the shell body 61 by screws, with good stability and easy disassembly, but not limited to this. The first electrode 1 and the second electrode 2 are preferably made of copper material, with high melting point, high conductivity, large rated current, low resistance and low power consumption, meeting the large current requirements, but not limited to this. In some embodiments, the first electrode 1 and the second electrode 2 can also be implemented by other metal materials.

[0036] In this specific embodiment, the first end of the conductive member 3 is electrically connected to the inner end of the first electrode 1 by welding, which has good firmness and electrical connection performance, but is not limited to this. In some embodiments, the first end of the conductive member 3 and the inner end of the first electrode 1 can also be fixedly electrically connected by other electrical connection methods.

[0037] Preferably, in this specific embodiment, the conductive member 3 is a flexible conductive member with a simple structure, easy to implement, and small deformation force, which reduces the elastic reset force requirement of the elastic release device 5 and has high reliability, but is not limited to this. In some embodiments, the conductive member 3 may also be other deformable structures, such as a hinge-type conductive member, a rotatable conductive member and other structures.

[0038] In this specific embodiment, the conductive member 3 is preferably a copper braided wire, which is beneficial to reducing the elastic reset force of the elastic release device 5, and has high conductivity, low resistance and low power consumption. Of course, in some embodiments, the conductive member 3 can also be implemented by other flexible and highly conductive metal bodies, such as a flexible conductor composed of multiple layers of copper sheets stacked together.

[0039] In this specific embodiment, the elastic release device 5 is implemented by a spring, more specifically a tension spring 51, which has a simple structure, is easy to implement, has low cost, and high reliability, but is not limited to this. In some embodiments, the elastic release device 5 can also be implemented by other elastic release devices such as compression springs and spring clips.

[0040] One end (right end) of the tension spring 51 is fixedly connected to the second end of the conductive member 3. Specifically, the right end of the tension spring 51 and the second end of the conductive member 3 are fixedly connected to the conductive fixing member 8 by high melting point solder, which is easy to process and has good stability, thereby improving reliability, but is not limited thereto. The other end (left end) of the tension spring 51 is fixed to the inner wall of the shell body 61 and is in a tensioned state. The tension spring 51 can be fixed to the inner wall of the shell body 61 by means of a hook or the like.

[0041] In this specific embodiment, the number of conductive members 3 is preferably two, and the two conductive members 3 are arranged in parallel on opposite sides of the tension spring 51, so that the structure is more evenly stressed and the stability and reliability are improved, but it is not limited to this. In some embodiments, the number of conductive members 3 can also be one or more than two.

[0042] Preferably, the left end of the stretch spring 51 is insulated from the first electrode 1 to ensure that the elastic state of the stretch spring 51 is not affected by the heating of the current, thereby ensuring the effectiveness of the elastic force in the low-rate and high-rate breaking processes.

[0043] Of course, in some embodiments, the elastic release device 5 and the conductive member 3 may also be implemented by elastically deformable conductive members.

[0044] In this specific embodiment, the conductive fixing member 8 is electrically connected to the first end of the first melt 4 by welding the low melting point metal 7, so that the second end of the conductive member 3 and the first end of the first melt 4 are electrically connected by welding the low melting point metal 7. In this specific embodiment, the low melting point metal 7 is a tin alloy, which is easy to implement and has low cost, but is not limited to this. In some embodiments, the low melting point metal 7 can also be implemented by other existing low melting point metals.

[0045] The first melt 4 can be made of copper, silver, aluminum or copper-based alloy, silver-based alloy, aluminum-based alloy or copper-silver composite material, etc., which has a high melting point and high electrical conductivity. After being made into a melt, compared with other melt materials of the same size, it has a large rated current, low resistance and low power consumption, and can easily meet the requirements of high breaking current capacity, but is not limited to this.

[0046] In this specific embodiment, the first melt 4 is a sheet structure, and is arranged in a undulating manner from the first end to the second end, so that the straight length of the first melt 4 is greater than the length of the shell body 61; and a plurality of narrow necks 41 are provided on the first melt 4, and the narrow necks 41 are arranged at intervals along the two ends of the first melt 4, thereby improving the breaking capacity of the first melt 4, with a fast breaking speed, stable performance, and high safety. Specifically, in this embodiment, the narrow neck 41 is formed by arranging a plurality of through holes arranged at intervals on the first melt 4.

[0047] The second end of the first melt 3 is welded to the second electrode 2 for electrical connection, which has good stability and conductivity, but is not limited thereto. In some embodiments, the first melt 3 and the second electrode 2 may also be an integrated structure, which has fewer parts and is easy to assemble.

[0048] In some embodiments, there may be multiple first fuses 4 , and multiple first fuses 4 are arranged in parallel, which is beneficial to improving the short-circuit breaking capacity of the fuse under high voltage and high current.

[0049] In this specific embodiment, a boss 611 is provided in the cavity of the shell body 61, the first melt 4 is arranged in the cavity of the shell body 61 located on the right side of the boss 611, and the first end of the first melt 4 is fixed on the boss 611, so that the first end of the first melt 4 is more stable. Preferably, the first end of the first melt 4 is fixed on the boss 611 by screw locking, and is pressed by the pressing block 6111, but it is not limited to this. In some embodiments, the boss 611 can also be replaced by a conductive plate (such as a copper plate), the conductive plate is fixed in the cavity of the shell body 61, the second end of the conductive member 3 is riveted to the conductive fixing member 8, the right end of the spring 51 is fixed by a buckle on the conductive fixing member 8, the conductive fixing member 8 is electrically connected to one side of the conductive plate through a low melting point metal, and the first melt 4 is electrically connected to the other side of the conductive plate.

[0050] Furthermore, the cavity on the right side of the boss 611 is filled with an arc extinguishing medium (not shown in the figure), so that the periphery of the first melt 4 is filled with the arc extinguishing medium, further improving the arc extinguishing ability. In this specific embodiment, the arc extinguishing medium is quartz sand, which is easy to implement and low in cost, but is not limited to this.

[0051] Working principle:

[0052] When a small overload current (low-rate overload current, such as less than 2 times the rated current) appears in the circuit and flows through the first electrode 1 and the second electrode 2 of the fuse, the conductive part 3 and the first melt 4 generate heat and transfer the heat to the low-melting-point metal 7. When the temperature reaches the melting point of the low-melting-point metal 7, its strength drops sharply. At this time, the tension spring 51 in the stretched state contracts, pulling the second end of the conductive part 3 back to the left so that the second end of the conductive part 3 is separated from the first melt 4, effectively disconnecting the circuit. When a short-circuit current (large overload current) appears in the circuit, a large short-circuit current flows through the first electrode 1 and the second electrode 2 of the fuse, and the first melt 4 quickly disconnects and cuts off the circuit under the action of the short-circuit current. The purpose of protecting the circuit is achieved.

[0053] Embodiment 2

[0054] like Figure 5-8 As shown, the difference between this embodiment and the first embodiment is that: this embodiment further includes a third electrode 201, a fourth electrode 202, a second shell 203 and a second melt 204, and the left and right ends of the second melt 204 (with Figure 7 and 8 The third electrode 201 and the fourth electrode 202 are respectively electrically connected to the third electrode 201 and the fourth electrode 202 (as a direction reference). Preferably, the left and right ends of the second melt 204 are respectively welded to the third electrode 201 and the fourth electrode 202 for electrical connection, which has good stability and conductivity, but is not limited thereto. The third electrode 201 and the fourth electrode 202 are respectively electrically connected to the first electrode 1 and the second electrode 2, so that the second melt 204 is arranged in parallel with the conductive member 3 and the first melt 4, further improving the breaking capacity of low-rate overload, and at the same time having the breaking capacity of large current short circuit.

[0055] In some embodiments, the second melt 204 and the third electrode 201 and the fourth electrode 202 may also be an integrated structure with fewer parts and easy assembly.

[0056] The second melt 204 can be made of copper, silver, aluminum or copper-based alloy, silver-based alloy, aluminum-based alloy or copper-silver composite material, etc., which has a high melting point and high electrical conductivity. After being made into a melt, compared with other melt materials of the same size, it has a large rated current, low resistance and low power consumption, and can easily meet the requirements of high breaking current capacity, but is not limited to this.

[0057] In this specific embodiment, the second melt 204 is a sheet structure, and is arranged in a high and low manner from the left end to the right end, so that the straight length of the second melt 204 is greater than the length of the second shell 203; and the second melt 204 is provided with a plurality of narrow necks 2041, and the narrow necks 2041 are arranged at intervals along the two ends of the second melt 204, thereby improving the breaking capacity of the second melt 204, with a fast breaking speed, stable performance, and high safety. Specifically, in this embodiment, the narrow neck 2041 is formed by arranging a plurality of through holes arranged at intervals on the second melt 204.

[0058] In this specific embodiment, the second housing 203 is an open rectangular parallelepiped structure, which is simple and compact, but is not limited to this. In some embodiments, the structure of the second housing 203 can be set according to actual needs. The second housing 203 is fixedly arranged on the first housing 6 and the opening of the second housing 203 is covered on the outer surface of the cover plate 62 and is closed by the cover plate 62. The structure is simple and the first housing 6 and the second housing 203 are separated, but is not limited to this. The second housing 203 and the first housing 6 are fixed by screws, which has good stability and is easy to disassemble and assemble, but is not limited to this.

[0059] The second shell 203 can be made of high-strength pressure-resistant insulating materials such as melamine and ceramics. The third electrode 201, the fourth electrode 202 and the second melt 204 are arranged in the cavity of the second shell 203, and the third electrode 201 and the fourth electrode 202 extend out of the left and right side walls of the second shell 203 along the length direction, respectively, to facilitate electrical connection in subsequent use. The second melt 204 is separated from the conductive member 3 and the first melt 4 and arranged in different cavities to further improve the breaking capacity, but it is not limited to this.

[0060] In this specific embodiment, the third electrode 201 and the fourth electrode 202 are both L-shaped sheet structures. The outer ends of the third electrode 201 and the fourth electrode 202 are respectively located outside the left and right side walls of the second shell 203, as connecting electrodes between the fuse and the external circuit. The inner ends of the third electrode 201 and the fourth electrode 202 are respectively located inside the left and right side walls of the second shell 203. The third electrode 201 and the fourth electrode 202 are both locked and fixed to the second shell 203 by screws, with good stability and easy disassembly and assembly, but not limited to this. The third electrode 201 and the fourth electrode 202 are preferably made of copper material, with high melting point, high conductivity, large rated current, low resistance and low power consumption, meeting the large current requirements, but not limited to this. In some embodiments, the third electrode 201 and the fourth electrode 202 can also be implemented by other metal materials.

[0061] In this specific embodiment, the outer end of the third electrode 201 is electrically connected to the outer end of the first electrode 1, and they together serve as one electrode of the fuse. The outer end of the fourth electrode 202 is electrically connected to the outer end of the second electrode 2, and they together serve as another electrode of the fuse. This facilitates subsequent wiring and has a simpler structure. It increases the strength of the electrode and is not easy to break, and is easy to manufacture. However, it is not limited to this. In some embodiments, the third electrode 201 and the first electrode 1 can be implemented by the same electrode, and the fourth electrode 202 and the second electrode 2 can be implemented by the same electrode.

[0062] Preferably, in this specific embodiment, the current carrying capacity of the second fuse 204 is smaller than the current carrying capacity of the first fuse 4 , which is beneficial for the second fuse 204 to quickly disconnect the circuit when a small current is overloaded.

[0063] Furthermore, the cavity of the second shell 203 is filled with an arc extinguishing medium (not shown in the figure), so that the arc extinguishing medium is filled around the second melt 204, further improving the arc extinguishing ability. In this specific embodiment, the arc extinguishing medium is quartz sand, which is easy to implement and low in cost, but is not limited to this.

[0064] Working principle:

[0065] When a small overload current appears in the circuit and flows through the fuse, the conductive member 3 and the first melt 4 generate heat and transfer the heat to the low-melting-point metal 7. When the temperature reaches the melting point of the low-melting-point metal 7, its strength drops sharply. At this time, the tension spring 51 in the stretched state contracts, pulling the second end of the conductive member 3 back to the left so that the second end of the conductive member 3 is separated from the first melt 4. Since the second melt 204 is still in the conducting state, no arc is generated during the separation process of the conductive member 3 and the first melt 4. When the overload current continues to exist, since the conductive member 3 and the first melt 4 have been disconnected, and the current carried by the second melt 204 is less than that of the first melt 4, the second melt 204 quickly melts and cuts off the circuit, thereby achieving the function of disconnecting the circuit under a small rate overload current. Therefore, the disconnection capacity of this embodiment can be significantly better than that of the first embodiment.

[0066] When a large short-circuit current appears in the circuit and flows through the fuse, since the short-circuit current is much larger than the carrying capacity of the first fuse 4 and the second fuse 204 in the fuse, the first fuse 4 and the second fuse 204 can quickly and safely cut off the circuit.

[0067] The utility model can realize the effect that the fuse can disconnect the circuit in time under the condition of low-rate overload, thereby avoiding the risk of burning of components and avoiding property loss, and no external triggering is required, the structure is simple, and it is easy to implement.

[0068] Although the present invention has been specifically demonstrated and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes may be made to the present invention in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A fuse capable of breaking a circuit at a low rate overcurrent, characterized in that: It includes a first electrode, a second electrode, a deformable conductive part, a first melt and an elastic release device, wherein the first end of the conductive part is electrically connected to the first electrode, the second end of the conductive part is electrically connected to the first end of the first melt by being fixed by welding with a low-melting-point metal, and the second end of the first melt is electrically connected to the second electrode. When the low-melting-point metal melts and softens under the action of an overload current, the conductive part is deformed under the action of the elastic release device so that the second end of the conductive part is away from the first end of the first melt.

2. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 1, characterized in that: The conductive element is a flexible conductive element.

3. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 2, characterized in that: The conductive member is a braided copper wire.

4. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 2, characterized in that: The elastic release device is implemented by a spring, one end of the spring is fixedly connected to the second end of the conductive member.

5. The fuse capable of breaking a circuit at a low overcurrent rate according to any one of claims 1 to 4, characterized in that: It also includes a first shell, the conductive member and the first melt are arranged in the cavity of the first shell, and the first electrode and the second electrode extend out of the first shell.

6. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 5, characterized in that: A boss is provided in the cavity of the first shell, and the first end of the first melt is fixed on the boss.

7. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 1, characterized in that: It also includes a second melt, which is arranged in parallel with the conductive member and the first melt.

8. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 7, characterized in that: The current carrying capacity of the second melt is less than the current carrying capacity of the first melt.

9. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 7 or 8, characterized in that: It also includes a second shell, a third electrode and a fourth electrode. The second melt is arranged in the cavity of the second shell, and the two ends are electrically connected to the third electrode and the fourth electrode respectively. The third electrode and the fourth electrode extend out of the second shell, and the third electrode and the fourth electrode are electrically connected to the first electrode and the second electrode respectively.

10. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 7 or 8, characterized in that: The first melt and the second melt are both sheet-like structures. The first melt and the second melt are provided with a plurality of narrow necks, which are spaced apart along the two end directions of the first melt and the second melt.

11. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 10, characterized in that: There are multiple first melts, and the multiple first melts are arranged in parallel.

12. The fuse capable of breaking a circuit at a low overcurrent rate according to claim 7 or 8, characterized in that: The first melt and the second melt are surrounded by arc extinguishing medium.

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