Hot melting cutter

Abstract

The invention relates to the technical field of hot melting cutters, in particular to a hot melting cutter and a battery module. The hot melting cutter comprises a first electrode, a second electrode, a fusible conductor and a heating body, and the first electrode and the second electrode are arranged at an interval; the fusible conductor is bridged between the first electrode and the second electrode; the heating body is located below the fusible conductor, the heating body is provided with a protruding face protruding in the direction close to the fusible conductor, the fusible conductor wraps at least part of the protruding face of the heating body, and the wrapped part of the heating body is tightly attached to the fusible conductor. Through the structural design of the heating body and the fusible conductor, the fusing effect can be effectively improved, and then the performance of the hot melting cutter is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal fuse cutouts, and in particular to a thermal fuse cutout. Background Art

[0002] The controlled thermal cutout is an overcurrent and overvoltage protection component, usually used for lithium-ion battery packs as secondary protection, so that it can act in time when it is exposed to overcurrent and overcharging risks, effectively reducing the fire and explosion caused by lithium-ion battery faults such as overcharging, overdischarging and short circuit, and keeping the damage to circuits and devices in the smallest possible area.

[0003] At present, the existing thermal cutoffs usually use a sheet-shaped heating sheet and a sheet-shaped fusible conductor mounted between the main circuit electrodes to heat and fuse the fusible conductor, thereby cutting off the circuit connection of the main circuit electrodes to achieve protection. However, the existing thermal cutoffs still have the limitations of the heating sheet not gathering heat, short creepage distance due to space limitations, and poor controlled fusing effect, and cannot be used in situations with higher precision and higher safety requirements. Summary of the invention

[0004] The present invention provides a thermal cutoff and a battery module, which can solve at least one problem in the background technology to improve the fusing effect of the thermal cutoff, thereby effectively improving product performance.

[0005] In a first aspect, an embodiment of the present invention provides a thermal fuse cutoff, which comprises at least: a first electrode, a second electrode, a fusible conductor, and a heating element; the first electrode and the second electrode are arranged at an interval; the fusible conductor is connected between the first electrode and the second electrode; the heating element is located below the fusible conductor; the heating element has a convex surface convex toward the fusible conductor, the fusible conductor wraps at least a portion of the convex surface of the heating element and the wrapped portion of the heating element is in close contact with the fusible conductor.

[0006] In some embodiments, the heating element includes a heating body and a heating pad, the heating body is formed with a heating contact surface on a side facing the fusible conductor, and the raised surface is located on the heating contact surface.

[0007] In some embodiments, the raised surface includes at least one of a single arc surface, multiple arc surfaces, multiple planes, and a combination of an arc surface and a plane; the fuse portion has a fusible contact surface formed on the side facing the heating element, and the heating element is in close contact with the fusible contact surface; the fusible contact surface includes a concave shape composed of at least one of a single arc surface, multiple arc surfaces, multiple planes, and a combination of an arc surface and a plane.

[0008] In some embodiments, a heating electrode is further included, wherein the heating electrode is located on one side of the heating element and is electrically connected to the heating element.

[0009] In some embodiments, the connecting part includes a fuse part and a connecting part, the connecting part includes a first connecting part and a second connecting part, the first connecting part and the second connecting part extend to both sides from the fuse part, the first connecting part is electrically connected to the first electrode, the second connecting part is electrically connected to the second electrode, and the first connecting part and the second connecting part are planar.

[0010] In some embodiments, the heating body is in the shape of a hollow column, a cylinder, a quasi-cylindrical column, a polygonal column, or a column consisting of one or more curved surfaces and / or planes.

[0011] In some embodiments, a flux is further included, and the flux is located on a surface of the fusible conductor on a side away from the heating element.

[0012] In some embodiments, it also includes a shell, which includes an upper shell and a lower shell, the upper shell and the lower shell are fixedly connected, and the lower shell is formed with a heating element accommodating portion; the heating element accommodating portion includes a plurality of limit blocks, and the heating element is clamped between the plurality of limit blocks.

[0013] In some embodiments, the shell further comprises a first electrode accommodating groove and a second electrode accommodating groove which penetrate the shell.

[0014] In some embodiments, the thermal cutoff further includes a sealing strip, the thickness of the sealing strip in the middle is thinner than the thickness at both ends; the sealing strip is arranged at one end of the first electrode close to the fusible conductor, and / or the sealing strip is arranged at one end of the second electrode close to the fusible conductor.

[0015] The thermal fuse cutoff provided by the present invention can enhance the heat collection effect of the heating element and increase the creepage distance through the structural design of the heating element and the fusible conductor, thereby effectively improving the fusing effect and further improving the performance of the thermal fuse cutoff.

[0016] Other features and advantages of the present invention will be set forth in the following description, and in part will be apparent from the description, or may be learned by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A three-dimensional exploded schematic diagram of a thermal cutoff provided by an embodiment of the present invention; Figure 2 A top partial cross-sectional view of a thermal fuse cutout provided by an embodiment of the present invention; Figure 3 A front cross-sectional view of a thermal fuse cutout provided by an embodiment of the present invention; Figures 4 to 10 Schematic diagrams of different modified embodiments of the fusible conductor provided by the present invention; Fig.11 Schematic diagram of the structure of the lower shell in the embodiment of the present invention.

[0019] Reference numerals: 10 - heating element; 11 - heating body; 12 - heating pad; 13 - heating electrode; 10a - heating contact surface; 20 - fusible conductor; 21 - fuse part; 22 - first connection part; 23 - second connection part; 20a - fusible contact surface; 31 - first electrode; 32 - second electrode; 40 - outer shell; 41 - upper shell; 42 - lower shell; 40a - first electrode accommodating groove; 40b - second electrode accommodating groove; 40c - heating electrode accommodating groove; 40d - heating element accommodating part; 50 - sealing strip; 60 - flux. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that all terms (including technical terms and scientific terms) used in the present invention have the same meanings as those generally understood by ordinary technicians in the field to which the present invention belongs, and should not be understood as limitations on the present invention; it should be further understood that the terms used in the present invention should be understood to have the same meanings as these terms in the context of this specification and in the relevant fields, and should not be understood in an idealized or overly formal sense, unless explicitly defined in this invention.

[0022] See also Figure 1 to Figure 3The present invention provides a thermal fuse cutout, which at least includes a first electrode 31, a second electrode 32, a heating element 10, and a fusible conductor 20. The first electrode 31 and the second electrode 32 are arranged at intervals; the fusible conductor 20 is bridged between the first electrode 31 and the second electrode 32, so that the fusible conductor 20 is electrically connected to the first electrode 31 and the second electrode 32 respectively to form a main circuit that is mutually conductive; the heating element 10 is in contact with the fusible conductor 20, and the heating pad 12 is located between the heating body 11 and the fusible conductor 20.

[0023] Its working principle is: when overvoltage occurs, the heating element 10 generates heat to cause the fusible conductor 20 above it to melt, thereby cutting off the main circuit. At the same time, when overcurrent occurs, the fusible conductor 20 itself generates heat and melts, thereby cutting off the main circuit.

[0024] In specific implementation, the first electrode 31 and the second electrode 32 are respectively formed of conductive materials such as Ag and Cu. In addition, it is preferred that a Ni / Au coating, a Ni / Pd coating, a Ni / Pd / Au coating or the like is applied on the surface of the first electrode 31 and the second electrode 32 by plating treatment to prevent the first electrode 31 and the second electrode 32 from being oxidized, and at the same time, to prevent the melting of the fusible conductor 20 from ablating the first electrode 31 and the second electrode 32. Preferably, the first electrode 31 and the second electrode 32 each include a first end, a second end and a narrow portion connecting the first end and the second end. The first end is used for electrical contact with the fusible conductor 20, and the second end is used for circuit connection of the main circuit. A structure with a smaller cross-sectional area is formed between the first end, the second end and the narrow portion by grooving or cutting part of the metal or reducing the thickness, so as to increase the resistance of the electrode end, increase the heat at the location more quickly, and achieve faster cutting.

[0025] The heating element 10 includes a heating body 11 and a heating pad 12 located on the heating body 11. The heating body 11 is made of insulating material, such as ceramic material, and a resistor is arranged inside the heating body 11. The heating pad 12 is made of a high melting point metal material, such as copper, silver, nickel and the like, and the specific material is set according to actual needs.

[0026] The fusible conductor 20 is preferably a low melting point metal material, such as a Pb-free solder of the SnAgCu system, a BiPbSn alloy, a BiPb alloy, a BiSn alloy, a SnPb alloy, a PbIn alloy, a ZnAl alloy, an InSn alloy, a PbAgSn alloy, etc. Of course, the fusible conductor 20 can also be a structure containing a high melting point metal and a low melting point metal. The specific configuration is based on actual needs, and the present embodiment is not limited thereto.

[0027] Furthermore, in order to control the heating of the heating element 10, the thermal fuse cutoff in this embodiment also includes a heating electrode 13, which is located on one side of the heating element 10 and is electrically connected to the heating element 10, so as to control the heating of the heating element 10 through the heating electrode 13 when the thermal fuse cutoff needs to be activated, thereby achieving the melting of the fusible conductor 20.

[0028] In order to solve the problem that the controlled fusing effect of the existing thermal fuse cutout is still poor, the present embodiment improves the structure of the heating element 10 and the fusible conductor 20. Specifically, the heating element 10 has a convex surface that convexes toward the fusible conductor 20, and the fusible conductor 20 wraps at least part of the convex surface of the heating element 10, and the wrapped part of the heating element 10 is close to the fusible conductor 20. The wrapping here means that the fusible conductor 20 at least partially surrounds and fits the convex surface to form a structure with a surrounding convex surface, and the surrounding and fitting part has a certain height and its slope changes, rather than just the fit of two planes.

[0029] By setting at least part of the surface of the heating element 10 as a convex surface, the contact area between the heating element 10 and the fusible conductor 20 can be increased in the effective space. At the same time, when the heating element 10 is heating, due to the presence of the convex surface and the wrapping of the fusible conductor 20, the heat of the heating element 10 can be more concentrated on the contact position between the convex surface and the fusible conductor 20, which effectively enhances the heat gathering effect of the heating element 10, so that the fusible conductor 20 can quickly absorb heat, thereby improving the controlled fusing effect and the response speed of the thermal fuse cutoff.

[0030] Preferably, the heating element 10 includes a heating body 11 and a heating pad 12, wherein the heating body 11 is formed with a heating contact surface 10a on the side facing the fusible conductor 20; the raised surface is located on the heating contact surface 10a, and the heating pad 12 at least covers the raised surface of the heating contact surface 10a and is in close contact with the fusible conductor 20.

[0031] In a specific implementation, the heating contact surface 10a is defined as the surface of the heating body 11 facing the fusible conductor 20, and at least part of the surface of the heating contact surface 10a is a convex surface that convexes toward the direction close to the fusible conductor 20. That is, part or all of the surface of the heating contact surface 10a is a convex surface. Among them, the convex surface can be located at one position or multiple positions on the heating contact surface 10a. That is, there can be one or more convex surfaces on the heating contact surface 10a. In this embodiment, the convex surface is preferably located in the middle of the heating contact surface 10a, and more preferably the convex surfaces are evenly and symmetrically distributed on the heating contact surface 10a. The non-heating contact surface portion of the heating body 10 can be designed into any shape as needed, and is not limited here.

[0032] In addition, the heating pad 12 is disposed between the heating contact surface 10a having the convex surface and the fusible conductor 20, which can effectively increase the distance between the first electrode 31 and the second electrode 32, thereby effectively improving the insulation withstand voltage capability after disconnection.

[0033] Preferably, the convex surface comprises a convex shape composed of at least one of a single curved surface, multiple curved surfaces, multiple planes, and a combination of curved surfaces and planes. Figure 4~Figure 7 The raised surface on the heating contact surface 10a is a curved surface. Figure 8 , Fig. 9 The raised surface of the heating contact surface 10a is a combination of multiple planes. Fig.10 The convex surface of the heating contact surface 10a is a combination of an arc surface and a plane, etc. The heating pad 12 at least covers the convex surface of the heating contact surface 10a. Therefore, the shape of the heating pad 12 is adapted to the shape of the convex surface or the heating contact surface 10a, and it also has a convex shape protruding toward the side of the fusible alloy. The specific structure can be referred to as shown in the attached drawings, and will not be repeated here.

[0034] Furthermore, the fusible conductor 20 is formed with a fusible contact surface 20a on the side facing the heating element 10, and the heating element 10 is closely attached to the fusible contact surface 20a. When the heating element 10 generates heat concentrated on the convex surface, it can be quickly transferred to the fusible contact surface 20a through the heating pad 12, thereby effectively melting the fusible conductor 20. Preferably, the fusible contact surface 20a includes a concave shape composed of a single arc surface, multiple arc surfaces, multiple planes, or a combination of an arc surface and a plane. For example Figure 4~Figure 7 The middle fusible contact surface 20a is an arc-shaped concave shape. Figure 8 , Fig. 9 The middle fusible contact surface 20a is a concave shape composed of multiple planes. Fig.10 The fusible contact surface 20a is a concave shape of a combination of an arc surface and a plane, etc. That is, the shape of the fusible contact surface 20a can be matched with the shape of the heating pad 12 and the heating contact surface 10a, and can be reasonably designed according to actual needs.

[0035] It should be noted that the structures of the heating contact surface 10a and the fusible contact surface 20a given in the drawings of the specification are merely examples, and the present embodiment is not limited thereto. Moreover, those skilled in the art may, based on the concept of the invention, also design the heating contact surface 10a and the fusible contact surface 20a into other structures that can increase the contact area between the heating element 10 and the fusible conductor 20 or can make the heat of the heating element 10 more concentrated at the contact position with the fusible conductor 20, all of which fall within the protection scope of the present invention.

[0036] Based on the above, preferably, the heating body 11 is in the shape of a hollow column, a cylinder, a quasi-cylindrical column, a polygonal column, or a column consisting of one or more arc surfaces and / or planes; the cross section of the heating body 11 is a regular polygon, a ring, or an ellipse, etc. For example Figure 4 The heating body 11 is cylindrical. Figure 5 The heating body 11 is a hollow column. Figure 6 The heating body 11 is in the shape of an elliptical column. Figure 8 The heating body 11 is a polygonal column. Figure 7 , Fig. 9 , Fig.10 The heating body 11 is a columnar structure formed by a curved surface and a flat surface. Preferably, the heating body 11 is an axisymmetric structure to ensure uniform heat conduction. In addition, the overall structure of the heating body 11 can also be any other strip structure, which is specifically designed according to actual application requirements, and this embodiment is not limited thereto.

[0037] In this embodiment, the heating element 10 is preferably cylindrical, the heating contact surface 10a is an arc surface matching the cylindrical heating element 10, and the fusible contact surface 20a is an arc surface with a curvature less than or equal to the heating contact surface 10a, so as to facilitate contact with the heating pad 12 on the heating contact surface 10a. Preferably, the arc radius of the fusible contact surface 20a is greater than the arc radius of the heating contact surface 10a.

[0038] In an optional embodiment, the fusible conductor 20 includes a fuse part 21 and a connecting part, and the connecting part is electrically connected to the first electrode 31 and the second electrode 32 respectively; the fuse part 21 and the connecting part are not on the same horizontal plane; the shape of the heating pad 12 matches the fuse part 21 and is close to the fuse part 21. That is, there is a height difference between the fuse part 21 and the connecting part. Through this arrangement, when the fuse part 21 is melted, the creepage distance can be increased due to the height difference, and the connection of the fusible conductor 20 between the two electrodes can be quickly cut off, further improving the breaking capacity of the thermal fuse cutoff.

[0039] Further, the connection portion of the fusible conductor 20 includes a first connection portion 22 and a second connection portion 23, wherein the first connection portion 22 and the second connection portion 23 extend from the fuse portion 21 to both sides, the first connection portion 22 is electrically connected to the first electrode 31, and the second connection portion 23 is electrically connected to the second electrode 32. In this embodiment, the first connection portion 22 and the second connection portion 23 are preferably planar, so as to better achieve contact with the first electrode 31 and the second electrode 32.

[0040] In an optional embodiment, the thermal fuse cutoff further includes a flux 60, which is located on a surface of the fusible conductor 20 away from the heating element 10. By providing the flux 60, the oxide layer on the surface of the fusible conductor 20 can be activated at high temperature, and the fusible conductor 20 is provided with a contraction tension, so that the thermal fuse cutoff can be more easily melted.

[0041] In other optional embodiments, the thermal fuse cutoff further comprises a housing 40. A cavity is formed inside the housing 40 to accommodate the fusible conductor 20, the heating element 10, and the ends of the first electrode 31 and the second electrode 32. Further, the housing 40 comprises an upper housing 41 and a lower housing 42, wherein the upper housing 41 and the lower housing 42 are fixedly connected, wherein the upper housing 41 and the lower housing 42 can be connected by, for example, rivets, and epoxy resin or sealant can be filled between the upper housing 41 and the lower housing 42 to achieve sealing of the thermal fuse cutoff. Preferably, the lower housing 42 is formed with a heating element accommodating portion 40d; the heating element accommodating portion 40d comprises a plurality of stop blocks, and the heating element 10 is clamped between the plurality of stop blocks. The stop blocks are integrally formed with the lower housing 42. The specific structure of the stop blocks can be designed according to the structure of the heating element 10, so that the heating element 10 can be restricted between the stop blocks and will not be displaced. This embodiment is not limited to the structure shown in the drawings of the specification.

[0042] Furthermore, the shell 40 is also formed with a plurality of interfaces that penetrate the inside and outside to facilitate the circuit to be led out. After the shell 40 is assembled with the internal components of the thermal cutoff, the interfaces can be sealed with epoxy resin to protect the thermal cutoff.

[0043] See also Fig.11 In this embodiment, the shell 40 is preferably further formed with a first electrode accommodating groove 40 a and a second electrode accommodating groove 40 a penetrating the shell 40 .

[0044] Specifically, the first electrode 31 is embedded in the first electrode receiving groove 40a, and the second electrode 32 is embedded in the second electrode receiving groove 40a, and the first electrode 31 can be fixed in the first electrode receiving groove 40a by epoxy resin, and the second electrode 32 can be fixed in the second electrode receiving groove 40a. The structures of the first electrode receiving groove 40a and the second electrode receiving groove 40a can be designed to match the actual structures of the first electrode 31 and the second electrode 32.

[0045] The thermal cut-off device further includes a sealing strip 50, which is disposed at the first electrode accommodating groove 40a of the first electrode 31 close to one end of the fusible conductor 20, and / or, the sealing strip 50 is disposed at the second electrode accommodating groove 40a of the second electrode 32 close to one end of the fusible conductor 20. The sealing strip 50 is a soft insulating material, such as a silicone strip. Preferably, the thickness of the sealing strip 50 in the middle is thinner than that at both ends. By designing the sealing strip 50 to be thin in the middle and thick on both sides, it is beneficial to buffer the pressure relief. In this embodiment, the upper shell 41 is preferably provided with a sealing groove, and the sealing strip 50 is assembled on the sealing groove.

[0046] The design of the sealing strip 50 not only achieves dustproof and waterproof effects, but also plays an exhaust role during disconnection, thereby achieving pressure relief inside the thermal cutoff, effectively protecting surrounding components, and improving the reliability of the thermal cutoff under overload conditions.

[0047] Preferably, the housing 40 is further formed with a heating electrode receiving groove 40c penetrating the housing 40. The heating electrode 13 is embedded in the heating electrode receiving groove 40c, and the heating electrode 13 can also be fixed in the heating electrode receiving groove 40c by epoxy resin.

[0048] It should be noted that, based on the above concept, according to different actual requirements of the thermal fuse cutout, those skilled in the art may also set other internal components on the thermal fuse cutout, all of which fall within the protection scope of the present invention.

[0049] The present invention also provides a battery module, which uses a thermal fuse as described in any of the above embodiments. The thermal fuse designed in this scheme is applied to the battery module. When the battery module has an overcurrent, the current passing through the fusible conductor 20 will cause the fusible conductor 20 to heat up and fuse due to the internal resistance inside the fusible conductor 20, thereby passively cutting off the conduction circuit; when the battery module is at risk of overcharging, the thermal fuse is turned on, and heat is generated by the thermal fuse. This heat can cause the fusible conductor 20 to fuse quickly under the action of the flux 60, thereby cutting off the conduction circuit between the first electrode 31, the second electrode 32 and the heating pad 12. The fusing action of the above-mentioned thermal fuse can kick out the out-of-control part of the module to prevent further expansion of the out-of-control range, effectively reduce the fire and explosion of the battery module due to overcharging, over-discharging or short circuit, and control the damage of the circuit and device to the smallest possible area.

[0050] In summary, the thermal fuse cutoff and battery module provided by the present invention can not only enhance the heat collection effect of the heating element, increase the creepage distance, and effectively improve the fusing effect through the structural design of the heating element 10 and the fusible conductor 20, but also effectively improve the insulation withstand voltage capacity after disconnection, thereby improving the controllability and reliability of the thermal fuse cutoff.

[0051] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, without having to solve all the technical problems listed in the prior art or background technology at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation on the claim.

[0052] Although the terms such as heating element, heating pad, first electrode, second electrode, fusible conductor, heating contact surface, fuse, fusible contact surface, heating electrode, heating pad, sealing strip, flux, shell, etc. are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention; the terms "first", "second", etc. (if any) in the description and claims of the embodiments of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A thermal cutoff device, characterized in that: include: A first electrode and a second electrode, wherein the first electrode and the second electrode are arranged at an interval; a fusible conductor connected between the first electrode and the second electrode; A heating element located below the fusible conductor; The heating element has a convex surface convex toward the fusible conductor, the fusible conductor wraps at least a portion of the convex surface of the heating element, and the wrapped portion of the heating element is in close contact with the fusible conductor.

2. The thermal cutoff according to claim 1, characterized in that: The heating element comprises a heating body and a heating pad. The heating body is formed with a heating contact surface on a side facing the fusible conductor, and the convex surface is located on the heating contact surface.

3. The thermal cutoff according to claim 1, characterized in that: The raised surface includes at least one of a single arc surface, multiple arc surfaces, multiple planes, and a combination of an arc surface and a plane; the fusible conductor is formed with a fusible contact surface on the side facing the heating element, and the heating element is tightly attached to the fusible contact surface; the fusible contact surface includes a concave shape composed of at least one of a single arc surface, multiple arc surfaces, multiple planes, and a combination of an arc surface and a plane.

4. The thermal cutoff according to claim 1, characterized in that: It also includes a heating electrode, which is located on one side of the heating element and is electrically connected to the heating element.

5. The thermal cutoff according to claim 1, characterized in that: The fusible conductor includes a fuse part and a connecting part, the connecting part includes a first connecting part and a second connecting part, the first connecting part and the second connecting part extend from the fuse part to both sides, the first connecting part is electrically connected to the first electrode, the second connecting part is electrically connected to the second electrode, and the first connecting part and the second connecting part are planar.

6. The thermal cutoff according to claim 2, characterized in that: The heating body is in the shape of a hollow column, a cylinder, a quasi-cylindrical column, a polygonal column, or a column consisting of one or more curved surfaces and / or planes.

7. The thermal cutoff according to claim 1, characterized in that: It also includes a flux, which is located on a surface of the fusible conductor on a side away from the heating element.

8. The thermal cutoff according to claim 1, characterized in that: It also includes a shell, which includes an upper shell and a lower shell, the upper shell and the lower shell are fixedly connected, and the lower shell is formed with a heating element accommodating portion; the heating element accommodating portion includes a plurality of limit blocks, and the heating element is clamped between the plurality of limit blocks.

9. The thermal cutoff according to claim 8, characterized in that: The shell is also formed with a first electrode accommodating groove and a second electrode accommodating groove which penetrate the shell.

10. The thermal cutoff according to claim 1, characterized in that: The thermal cutoff includes a sealing strip, the thickness of the sealing strip in the middle is thinner than that at both ends; the sealing strip is arranged at one end of the first electrode close to the fusible conductor, and / or the sealing strip is arranged at one end of the second electrode close to the fusible conductor.

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