A hot melt disconnector and protection circuit
By designing the non-welding and welding areas of the fusible alloy in the thermomelting cutter to have unequal cross-sectional areas, the problem of inconsistent melting positions is solved, achieving synchronous and reliable melting, and reducing cost and volume.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- XIAMEN SET ELECTRONICS CO LTD
- Filing Date
- 2025-06-20
- Publication Date
- 2026-06-16
Smart Images
Figure CN224366819U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of thermosetting cutters, and in particular to a thermosetting cutter and its protection circuit. Background Technology
[0002] Controlled thermal fuses are surface-mount products typically used in lithium-ion battery packs as secondary protection. They activate promptly in the event of overcurrent or overcharge risks, effectively reducing the risk of fires and explosions caused by overcharging, over-discharging, and short circuits, thus minimizing damage to circuits and components. Existing battery pack protection circuits often use multiple controlled thermal fuses connected in parallel to handle high current or overvoltage situations. However, when multiple thermal fuses are connected in parallel for protection, some fuse elements may fail to blow in time, and the breakage positions of the fuse elements may be inconsistent. This allows current to continue flowing through the unblown fuse elements, affecting the reliability of the protection circuit.
[0003] To address this issue, existing technologies typically employ the addition of unidirectional diodes for unidirectional control. While this method can limit current flow to some extent and reduce the likelihood of fuses failing to blow in time, it introduces new problems. Firstly, adding unidirectional diodes undoubtedly increases circuit cost and the overall product price. Secondly, the additional diodes occupy circuit board space, increasing the size of the protection circuit and hindering miniaturization and integration. More importantly, adding unidirectional diodes does not fundamentally solve the problem of some fuses failing to blow in time, and the reliability of the protection circuit remains unreliable. Utility Model Content
[0004] This utility model provides a thermoplastic cutter that can solve at least one problem in the background art to improve the consistency of the position of the melt cut of the thermoplastic cutter and improve product performance.
[0005] This invention provides a thermoforming cutter, which includes at least a heating element and a fusible alloy. The heating element includes at least a heating pad located on its surface and a first electrode and a second electrode located on opposite sides along the length of the heating pad. The fusible alloy is located on the heating element and is welded to the heating pad by solder. The first electrode is connected to the second electrode via the fusible alloy. The fusible alloy has a welding area located in the middle and in contact with the heating pad, and a first non-welding area and a second non-welding area located on either side of the welding area and not in contact with the heating pad. The total cross-sectional area of the first non-welding area along a plane parallel to the X-plane is not equal to the total cross-sectional area of the second non-welding area along a plane parallel to the X-plane. The X-plane is defined as the plane formed by the intersection of the length direction and the thickness direction of the heating pad.
[0006] In some embodiments, the first non-welded area includes a first fused area that is not in contact with the first electrode or the second electrode; the second non-welded area includes a second fused area that is not in contact with the first electrode or the second electrode; the total cross-sectional area of the first fused area along the X-plane is not equal to the total cross-sectional area of the second fused area along the X-plane.
[0007] In some embodiments, when viewed from above the thermoplastic cutter toward the fusible alloy, the shapes of the first non-welded area and the second non-welded area are asymmetrically distributed with respect to the fusible alloy along a centerline parallel to the X-plane; or, when viewed from above the thermoplastic cutter toward the fusible alloy, the shapes of the first melt-cut area and the second melt-cut area are asymmetrically distributed with respect to the fusible alloy along a centerline parallel to the X-plane.
[0008] In some embodiments, the first non-welded area and / or the second non-welded area are provided with a notch recessed toward the interior of the fusible alloy; or, the first melting area and / or the second melting area are provided with a notch recessed toward the interior of the fusible alloy; the location of the notch forms a minimum cross-sectional area parallel to the X-plane.
[0009] In some embodiments, the first non-welded area and / or the second non-welded area are provided with at least one through groove; or, the first fused area and / or the second fused area are provided with at least one through groove; the location of the through groove has a minimum cross-sectional area parallel to the X plane.
[0010] In some embodiments, the first non-welded area and / or the second non-welded area are provided with a notch recessed toward the interior of the fusible alloy and at least one through groove; or, the first melt-breaking area and / or the second melt-breaking area are provided with a notch recessed toward the interior of the fusible alloy and at least one through groove.
[0011] In some embodiments, when viewed from above the thermoplastic cutter toward the fusible alloy, the notch is rectangular, V-shaped, trapezoidal, or arc-shaped.
[0012] In some embodiments, the minimum cross-sectional area of the welded area along the X-plane is greater than the minimum cross-sectional area of the first non-welded area or the second non-welded area along the X-plane.
[0013] In some embodiments, the device further includes a housing and a fluxing agent, the fluxing agent being located above the welding area on the surface of the fusible alloy away from the heating element; the housing has an internal cavity to accommodate the fluxing agent and the fusible alloy between the housing and the heating element.
[0014] This utility model also provides a protection circuit, including multiple parallel-connected thermoplastic cutters, wherein the thermoplastic cutters are as described in any of the above embodiments; in all parallel-connected thermoplastic cutters, the total cross-sectional area of the first non-welded area or the second non-welded area near the current input side along the X-plane is greater than the total cross-sectional area of the second non-welded area or the first non-welded area near the current output side along the X-plane; or, in all parallel-connected thermoplastic cutters, the total cross-sectional area of the first non-welded area or the second non-welded area near the current input side along the X-plane is less than the total cross-sectional area of the second non-welded area or the first non-welded area near the current output side along the X-plane.
[0015] The thermoelectric cutter provided by this utility model has a design that makes the cross-sectional area of the fusible alloy different at different positions. This design ensures that the side with the smaller total cross-sectional area absorbs energy and forms a melt first while ensuring current carrying capacity. This makes the melt-breaking position of each thermoelectric cutter located at a fixed position on the same side, thereby ensuring that each thermoelectric cutter can melt simultaneously. This ensures that the circuit can be disconnected in time when there is overcurrent or overvoltage, and improves the reliability of the thermoelectric cutter.
[0016] Other features and beneficial effects of this invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing this invention. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0018] Figure 1 This is a three-dimensional exploded view of a thermoelectric cutter provided in an embodiment of the present invention;
[0019] Figure 2 A top view schematic diagram of the connection between the heating element and the fusible alloy provided in an embodiment of this utility model;
[0020] Figure 3 This is a cross-sectional view of a thermoplastic cutter provided in an embodiment of the present invention;
[0021] Figures 4 to 14 Schematic diagrams of different modified embodiments of the fusible alloy provided by this utility model;
[0022] Figure 15 An equivalent current diagram of the current formed when the fusible alloys of each thermal switch in the protection circuit provided in an embodiment of the present invention melt on the same side;
[0023] Figure 16 This is an equivalent current diagram of the random melting of the fusible alloy of each thermoelectric cutter on different sides in a conventional protection circuit.
[0024] Figure label:
[0025] 10 – Heating element; 11 – Heating pad; 12 – First electrode; 13 – Second electrode; 20 – Fusible alloy; 201 – Welding area; 202 – First non-welding area; 203 – Second non-welding area; 202a – First fusing area; 203a – Second fusing area; 21 – Notch; 22 – Through groove; 30 – Flux for fusing; 40 – Outer shell. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. The technical features designed in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.
[0027] In the description of this utility model, it should be noted that all terms used in this utility model (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model pertains, and should not be construed as limiting this utility model; it should be further understood that the terms used in this utility model should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this utility model.
[0028] Please see Figures 1-3 This utility model provides a thermoplastic cutter, which includes at least a heating element 10 and a fusible alloy 20. The fusible alloy 20 is located on the heating element 10. The heating element 10 includes at least a heating pad 11 located on the surface of the heating element 10 and a first electrode 12 and a second electrode 13 located on opposite sides along the length direction of the heating pad 11. The fusible alloy 20 is connected to the first electrode 12, the second electrode 13, and the heating pad 11 to form an interconnected circuit.
[0029] For details, please refer to Figure 1 The heating element 10 also includes a heating body and an internal resistor (not shown in the figure). Preferably, the resistors within the heating element 10 are concentrated below the heating pad 11, allowing the heating pad 11 to quickly absorb heat and increase the melting speed of the fusible alloy 20. The heating body is made of an insulating material, such as ceramic, and contains an internal resistor. During an overvoltage, the heating element 10 heats up, causing the fusible alloy 20 above the heating pad 11 to melt, thus cutting off the conductive circuit. Simultaneously, during an overcurrent, the fusible alloy 20 heats up and melts, also cutting off the conductive circuit. The ends of the first electrode 12 and the second electrode 13 are mounted on the surface of the heating element 10. The first electrode 12, the second electrode 13, and the heating pad 11 are each coated with a metal layer, which can be made of tin, silver, gold, etc. By configuring the heating element, resistor, first electrode 12, second electrode 13, and fusible alloy 20 as described above, the heat transfer path is shortened, and the heat transfer is faster and more efficient. This also prevents the first electrode 12, second electrode 13, and resistor attached to the surface of the heating element 10 from breaking down again after the current path is cut off at high temperatures, thereby improving the efficiency of heat transfer.
[0030] The fusible alloy 20 is soldered to the heating pad 11 using solder. The fusible alloy 20 is preferably a low-melting-point fusible alloy 20. (See also...) Figure 2 The fusible alloy 20 has a welding area 201 located in the center and in contact with the heating pad 11, and a first non-welding area 202 and a second non-welding area 203 located on both sides of the welding area 201 and not in contact with the heating pad 11. The total cross-sectional area of the first non-welding area 202 along a plane parallel to the X-plane is not equal to the total cross-sectional area of the second non-welding area 203 along the same plane. The X-plane is defined as the plane formed by the intersection of the length direction and the thickness direction of the heating pad 11.
[0031] It should be noted that the heating pad 11 can be arranged parallel to or at a certain angle along its length within the width range between the first electrode 12 and the second electrode 13. The length direction of the heating pad 11 is not consistent with the current flow direction between the first electrode 12 and the second electrode 13. In this embodiment, it is preferable that the length direction of the heating pad 11 is perpendicular to the current flow direction between the first electrode 12 and the second electrode 13, for example... Figure 2 The X-direction in the diagram represents the length direction of the heating pad 11, and the Y-direction represents the current flow direction between the first electrode 12 and the second electrode 13. It should also be noted that the thickness direction of the heating pad 11 refers to the direction perpendicular to the surface of the heating pad 11, for example... Figure 3 The Z-direction shown in the figure represents the thickness direction of the heating pad 11. Therefore, the "X-plane" here is defined as the plane formed by the intersection of the length direction (X-direction) and the thickness direction (Z-direction) of the heating pad 11. Further, the first non-welded area 202 and the second non-welded area 203 can be cut along a plane parallel to the X-plane to form a series of cross-sections. The "total cross-sectional area of the first non-welded area 202 along the plane parallel to the X-plane" refers to the sum of the cross-sectional areas of all cross-sections formed by the first non-welded area 202 parallel to the X-plane. Similarly, the "total cross-sectional area of the second non-welded area 203 along the plane parallel to the X-plane" refers to the sum of the cross-sectional areas of all cross-sections formed by the second non-welded area 203 parallel to the X-plane.
[0032] Specifically, the fusible alloy 20 includes a welded area 201 and a non-welded area. The non-welded area includes a first non-welded area 202 and a second non-welded area 203. In this embodiment, the total cross-sectional areas of the first non-welded area 202 and the second non-welded area 203 can be made unequal along the X-plane by creating through slots, cutting off parts of the alloy, or reducing the thickness in the first non-welded area 202 and / or the second non-welded area 203.
[0033] With the above configuration, when the fusible alloy 20 melts, the soldered area is less likely to tear because the middle part of the fusible alloy 20 is soldered to the heating pad 11 via solder paste. This locks the tear (break) location to two non-soldering areas. Furthermore, due to the difference in the total cross-sectional area of the non-soldering areas of the fusible alloy 20, the non-soldering area with the smaller total cross-sectional area forms the fuse opening and absorbs energy first, thus melting preferentially. This mechanism ensures that each thermoelectric cutter can melt synchronously in the same non-soldering area. In other words, this design makes the fuse opening position of multiple thermoelectric cutters connected in parallel in the protection circuit deterministic when they melt, effectively avoiding randomness in the melting process and preventing the risk that some fuse elements will not melt in time. This fundamentally solves the problem that some fuse elements cannot melt in time due to inconsistent fuse openings, significantly improving the reliability of the thermoelectric cutter. At the same time, by optimizing the design of the fusible alloy 20, the need to add additional protectors or increase the rated current value can be avoided, thereby reducing costs.
[0034] Furthermore, the cross-sectional area of the welding zone 201 may be completely or partially consistent along all sections parallel to the X-plane. That is, the cross-sectional area of the welding zone 201 may remain unchanged or be without a narrow diameter, or the cross-sectional area may be altered by creating a narrow diameter through a through-hole, a partially penetrating groove, cutting off a portion of the alloy, or reducing the thickness. The specific shape and structure are rationally set according to actual needs. For example... Figure 2 The cross-sectional area of the welding area 201 shown remains unchanged, as follows: Figure 4 The cross-sectional area of the welded area 201 shown is changed. In this embodiment, it is preferable that the cross-sectional area of the welded area 201 remains unchanged, while the total cross-sectional area of the non-welded areas on both sides is different, thereby ensuring that the non-welded area on one side absorbs more heat and forms a fusion fracture, and the area where the fusion fracture is formed is determined and unique.
[0035] In a preferred embodiment, please refer to Figure 5 A notch 21 is provided only in the first non-welded area 202 to ensure that the total cross-sectional area of the first non-welded area 202 is smaller than the total cross-sectional area of the second non-welded area 203, and the fusion break location appears at the notch 21 in the first non-welded area 202. The first non-welded area 202 includes a first fusion break area 202a that does not contact the first electrode 12 or the second electrode 13; the second non-welded area 203 includes a second fusion break area 203a that does not contact the first electrode 12 or the second electrode 13. The total cross-sectional area of the first fusion break area 202a along the X-plane is not equal to the total cross-sectional area of the second fusion break area 203a along the X-plane.
[0036] It should also be noted that, similarly, the first fusing zone 202a can be cut into a series of cross-sections along a plane parallel to the X-plane. Here, "the total cross-sectional area of the first fusing zone 202a along a plane parallel to the X-plane" refers to the sum of the cross-sectional areas of all cross-sections formed by the first fusing zone 202a along the X-plane. The "minimum cross-sectional area of the second fusing zone 203a along a plane parallel to the X-plane" refers to the sum of the cross-sectional areas of all cross-sections formed by the second fusing zone 203a along the X-plane.
[0037] In specific implementation, the total cross-sectional area of the first non-welded area 202 along the length direction parallel to the heating pad 11 can be made unequal to the total cross-sectional area of the second non-welded area 203 along the length direction parallel to the heating pad 11 by opening through slots, incompletely penetrating grooves, cutting off part of the alloy, or reducing the thickness at the first melting zone 202a and / or the second melting zone 203a. For example Figure 5 , Figure 6 Different variations of the fusible alloy 20 shown employ methods such as creating a through groove 22, cutting off a portion of the alloy, or a combination of both.
[0038] By setting the cross-sectional area relationship between the first fusing zone 202a and the second fusing zone 203a as described above, the structure of the fusible alloy 20 can be effectively adjusted. Furthermore, when the fusible alloy 20 melts, the different cross-sectional areas within it ensure that multiple thermoplastic cutters can melt synchronously in the same fusing zone, thereby preventing the risk of some fuse elements failing to melt in time and improving the reliability of the fuse.
[0039] Further, please refer to Figures 4 to 14 Viewed from above the thermoplastic cutter toward the fusible alloy 20, the shapes of the first non-welding area 202 and the second non-welding area 203 are asymmetrically distributed relative to the fusible alloy 20 along a centerline parallel to the X-plane; or, viewed from above the thermoplastic cutter toward the fusible alloy 20, the shapes of the first melting area 202a and the second melting area 203a are asymmetrically distributed relative to the fusible alloy 20 along a centerline parallel to the X-plane.
[0040] Specifically, the plane of a conventional fusible alloy 20 is generally axisymmetric to facilitate uniform heat transfer to all parts of the fusible alloy 20. However, when the conventional shape of the fusible alloy 20 is applied to a thermoplastic cutter, its melting point is random. This can easily lead to inconsistencies in the melting points between different thermoplastic cutters when multiple thermoplastic cutters are connected in parallel, resulting in the risk that some thermoplastic cutters may not be melted in time. Figure 16 As shown.
[0041] Therefore, unlike the conventional axisymmetric fusible alloy 20, this embodiment achieves an asymmetrical distribution relative to the fusible alloy 20 along a centerline parallel to the X-plane by altering the shapes of the first non-welding area 202 and the second non-welding area 203, or by altering the shapes of the first melting area 202a and the second melting area 203a. This design effectively addresses the aforementioned shortcomings of conventional fusible alloy 20 applications. The centerline of the fusible alloy 20 along the X-plane refers to a reference line parallel to the X-plane and passing through the geometric center of the fusible alloy 20. This reference line is generally located within the central welding area 201, for example... Figure 4 The dotted line A shown in the diagram.
[0042] Based on the above, please refer to further information. Figures 4 to 14 Viewed from above the thermoplastic cutter towards the fusible alloy 20, the shapes of the first non-welding area 202 and the second non-welding area 203 are symmetrically distributed with respect to the fusible alloy 20 along a centerline perpendicular to the X-plane; or, viewed from above the thermoplastic cutter towards the fusible alloy 20, the shapes of the first melting area 202a and the second melting area 203a are symmetrically distributed with respect to the fusible alloy 20 along a centerline perpendicular to the X-plane. Here, the centerline of the fusible alloy 20 along the X-plane refers to a reference line perpendicular to the X-plane and passing through the geometric center of the fusible alloy 20. This reference line generally passes through the central welding area 201, for example... Figure 4 The dotted line B shown in the diagram.
[0043] This design not only solves the problem of randomness in the melting point, but also helps to evenly transfer the heat on the heating element 10 to the melting point, so that the fusible alloy 20 can reach the melting point more synchronously at the melting point position along the X direction, ensuring the consistency and reliability of the melting.
[0044] Preferably, please refer to Figure 4 , Figure 14 The minimum cross-sectional area of the soldering area 201 along the X-plane is greater than the minimum cross-sectional area of the first non-soldering area 202 or the second non-soldering area 203 along the X-plane. In specific implementation, the above setting can further improve the fusing effect. At the same time, since solder paste is soldered between the soldering area 201 and the heating pad 11, it effectively ensures that when the total cross-sectional areas of the non-soldering areas are not equal, the fusing point will first appear in the non-soldering area with the smaller total cross-sectional area rather than in the soldering area, thereby ensuring fusing consistency and shortening the fusing time.
[0045] In an alternative embodiment, please refer to Figure 2 , Figures 4-8The first non-welded area 202 and / or the second non-welded area 203 are provided with a notch 21 that is recessed toward the interior of the fusible alloy 20; or, the first melting area 202a and / or the second melting area 203a are provided with a notch 21 that is recessed toward the interior of the fusible alloy 20; the notch 21 is located at a minimum cross-sectional area parallel to the X plane.
[0046] Specifically, the notch 21 can be formed only at both ends of the non-welded area or at both ends of the fusion zone, or it can be formed at one end of the non-welded area or the fusion zone. There can be one or more notches 21, and their specific number, shape, size and position design can be reasonably adjusted according to actual needs and specific current rating and fusing requirements to ensure that it can be quickly and reliably fusing when overcurrent occurs. No further restrictions are imposed here.
[0047] By designing the notch 21, the cross-sectional area of the fusible alloy 20 at the notch 21 position can be reduced, thereby achieving a discrepancy between the total cross-sectional areas of the first non-welded area 202 and the second non-welded area 203, or between the total cross-sectional areas of the first melting area 202a and the second melting area 203a. Furthermore, the notch 21 of the fusible alloy 20 can be cut and shaped using methods such as laser cutting, chemical etching, or machining, resulting in low manufacturing costs.
[0048] Furthermore, to ensure the uniformity of the melting of the fusible alloy 20, the notch 21 is preferably designed to be axisymmetric. As an example, the notch 21 can be rectangular, V-shaped, trapezoidal, arc-shaped, or any combination of lines and surfaces. For example... Figure 2 , Figure 4 , Figure 5 The central notch 21 has an inwardly concave V-shaped structure. Figure 6 The central notch 21 has an inwardly concave rectangular structure. Figure 7 The central notch 21 has an inwardly concave U-shaped structure. Figure 8 The central notch 21 has an inwardly concave trapezoidal and arc-shaped structure. Of course, according to this concept, the notch 21 can also be designed into other regular axisymmetric shapes, and the embodiments disclosed herein are not limited thereto.
[0049] In another alternative embodiment, please refer to Figures 9-11 The first non-welded area 202 and / or the second non-welded area 203 are provided with at least one through groove 22; or, the first fusion area 202a and / or the second fusion area 203a are provided with at least one through groove 22; the through groove 22 is located at a position that forms a minimum cross-sectional area parallel to the X plane.
[0050] Specifically, to ensure the uniformity of the fusible alloy 20 during the melting process, the shape of the through-slot 22 in top view is preferably an axisymmetric shape. As an example, the shape of the through-slot 22 in top view can be circular, rectangular, racetrack-shaped, or other regular shapes. For example, Figure 9 The through-slot 22 is racetrack shaped. Figure 10 , Figure 11 The through-slot 22 is circular. The shape, number, and spacing between the through-slots 22 can be reasonably designed according to the actual size of the fusible alloy 20, and are not limited here.
[0051] By providing through grooves 22 on the fusible alloy 20 as described above, the total cross-sectional areas of the first non-welded area 202 and the second non-welded area 203 are not equal, or the total cross-sectional areas of the first melting area 202a and the second melting area 203a are not equal.
[0052] In other alternative embodiments, please refer to Figures 12-14 The first non-welded area 202 and / or the second non-welded area 203 are provided with a notch 21 recessed toward the interior of the fusible alloy 20 and at least one through groove 22; or, the first melting area 202a and / or the second melting area 203a are provided with a notch 21 recessed toward the interior of the fusible alloy 20 and at least one through groove 22. That is, the welded area 201 or the melting area may be provided with both a notch 21 and a through groove 22 to improve the breaking capacity.
[0053] Better, such as Figure 1 or Figure 3 As shown, the thermoplastic cutter may further include a housing 40 and a flux 30. The flux 30 is located above the welding area 201 on the surface of the fusible alloy 20 away from the heating element 10. By providing the flux 30, the oxide layer on the surface of the fusible alloy 20 can be activated at high temperatures, and tension is provided to prevent the fusible alloy 20 from shrinking. A cavity is formed inside the housing 40 to accommodate the flux 30 and the fusible alloy 20 between the housing 40 and the heating element 10. The housing 40 may include a shell and a cover, which are detachably and fixedly connected to secure the internal components of the thermoplastic cutter within the housing 40. Preferably, the surface of the housing 40 has several interfaces to facilitate wiring. After the housing 40 is assembled with the internal components of the thermoplastic cutter, the interfaces can be sealed with epoxy resin to protect the thermoplastic cutter.
[0054] It should be noted that, based on the above concept, and depending on the actual needs of the thermomelt cutter, those skilled in the art may also add other internal components to the thermomelt cutter, all of which fall within the protection scope of this utility model.
[0055] This utility model also provides a protection circuit, including multiple parallel-connected thermoplastic cutters. The thermoplastic cutters are those described in any of the above embodiments. That is, the non-welding areas at different locations of the fusible alloy 20 in each thermoplastic cutter employ the aforementioned design with unequal total cross-sectional areas.
[0056] Among all the parallel-connected thermoplastic cutters, the total cross-sectional area of the first non-welded area 202 or the second non-welded area 203 near the current input side along the X-plane is greater than the total cross-sectional area of the second non-welded area 203 or the first non-welded area 202 near the current output side along the X-plane; or, among all the parallel-connected thermoplastic cutters, the total cross-sectional area of the first non-welded area 202 or the second non-welded area 203 near the current input side along the X-plane is less than the total cross-sectional area of the second non-welded area 203 or the first non-welded area 202 near the current output side along the X-plane.
[0057] Specifically, when multiple thermoplastic cutters are installed in parallel in a protection circuit, the total cross-sectional area of the first non-welded area 202 of all the parallel thermoplastic cutters along the X-plane is greater than the total cross-sectional area of the second non-welded area 203 along the X-plane, or the total cross-sectional area of the first non-welded area 202 of all the parallel thermoplastic cutters along the X-plane is less than the total cross-sectional area of the second non-welded area 203 along the X-plane. That is, it is ensured that the minimum total cross-sectional area of each thermoplastic cutter is located either in the non-welded area on the current input side or in the non-welded area on the current output side. When current or overvoltage occurs in the circuit, a fusible link will be formed at the minimum total cross-sectional area of all the parallel thermoplastic cutters and will be preferentially melted, ensuring that the circuit is disconnected faster and more promptly.
[0058] For example Figure 15 The diagram shown is the equivalent current diagram of the fusible alloy 20 of each thermoelectric switch in the protection circuit provided in this embodiment when it melts on the same side. It shows that the current path of the three thermoelectric switches is formed by the current input side (i.e., the non-welded area on one side of the fusible alloy 20) of each thermoelectric switch, and the current flow path can be melted simultaneously more quickly. For example... Figure 16 The diagram shows the equivalent current generated when the fusible alloy 20 of each thermoelectric cutter randomly melts on different sides in a conventional protection circuit. Each thermoelectric cutter may form a fusible contact point in the non-welded area on different sides, making it easier for the current flow path to be difficult to interrupt in time. That is, if conventional thermoelectric cutters are connected in parallel in the protection circuit, the random melting positions of the fusible contacts can easily lead to inconsistent melting times for each thermoelectric cutter, causing some to fail to melt in time. This allows current to continue flowing through the unmelted fuse elements, resulting in protection failure.
[0059] Therefore, by improving the fusible alloy of the thermoelectric cutter and applying it to the protection circuit, the out-of-control part can be kicked out of the module in a timely and effective manner, preventing the further expansion of the out-of-control range, effectively reducing the possibility of protection circuit failure, and keeping the damage to the circuit and devices within the smallest possible area.
[0060] It should also be noted that the thermal fuse cutters and protection circuits provided in the above embodiments can be widely used in various electronic devices requiring overcurrent or overvoltage protection, such as mobile phones, laptops, electric vehicles, and electric bicycles. By ensuring the consistency of the break at the time of melting, the reliability of the protection circuit is improved, and the risk of equipment damage due to protection failure is reduced.
[0061] In summary, the thermosetting cutter and battery module provided by this utility model, through the structural design of the fusible alloy, ensure the consistency of the fracture surface during melting, avoiding the problem of random fractures occurring when multiple thermosetting cutters are connected in parallel, resulting in some thermosetting cutters failing to cut off in time. This design not only improves the reliability of the protection circuit but also reduces costs, and has broad application prospects.
[0062] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of this utility model can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.
[0063] Although this document frequently uses terms such as heating element, heating pad, first electrode, second electrode, fusible alloy, welding area, first non-welding area, second non-welding area, first melting zone, second melting zone, through groove, notch, flux, and shell, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any kind of additional limitation would contradict the spirit of this utility model. The terms "first," "second," etc. (if present), in the description, claims, and accompanying drawings of the embodiments of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.
[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.
Claims
1. A thermoforming cutter, characterized in that, include: A heating element; the heating element includes at least a heating pad located on the surface of the heating element and a first electrode and a second electrode located on opposite sides along the length direction of the heating pad; A fusible alloy is located on the heating element and welded to the heating pad by solder; the first electrode is connected to the second electrode through the fusible alloy; the fusible alloy has a welding area located in the middle and in contact with the heating pad, and a first non-welding area and a second non-welding area located on both sides of the welding area and not in contact with the heating pad; The total cross-sectional area of the first non-welded area along the X-plane is not equal to the total cross-sectional area of the second non-welded area along the X-plane; the X-plane is defined as the plane formed by the intersection of the length direction of the heating pad and the thickness direction of the heating pad.
2. The thermosetting cutter according to claim 1, characterized in that: The first non-welded area includes a first fusion-break area that is not in contact with the first electrode or the second electrode; the second non-welded area includes a second fusion-break area that is not in contact with the first electrode or the second electrode. The total cross-sectional area of the first fusing zone along the plane parallel to the X is not equal to the total cross-sectional area of the second fusing zone along the plane parallel to the X.
3. The thermosetting cutter according to claim 2, characterized in that: Viewed from above the thermoplastic cutter toward the fusible alloy, the shapes of the first non-welded area and the second non-welded area are asymmetrically distributed with respect to the fusible alloy along a centerline parallel to the X-plane; or, viewed from above the thermoplastic cutter toward the fusible alloy, the shapes of the first melting area and the second melting area are asymmetrically distributed with respect to the fusible alloy along a centerline parallel to the X-plane.
4. The thermosetting cutter according to claim 2, characterized in that: The first non-welded area and / or the second non-welded area are provided with a notch that is recessed toward the interior of the fusible alloy; or, the first melting area and / or the second melting area are provided with a notch that is recessed toward the interior of the fusible alloy; the location of the notch forms a minimum cross-sectional area parallel to the X-plane.
5. The thermosetting cutter according to claim 2, characterized in that: The first non-welded area and / or the second non-welded area are provided with at least one through groove; or, the first fused area and / or the second fused area are provided with at least one through groove; the location of the through groove forms a minimum cross-sectional area parallel to the X plane.
6. The thermosetting cutter according to claim 2, characterized in that: The first non-welded area and / or the second non-welded area are provided with a notch recessed toward the interior of the fusible alloy and at least one through groove; or, the first melt-breaking area and / or the second melt-breaking area are provided with a notch recessed toward the interior of the fusible alloy and at least one through groove.
7. The thermosetting cutter according to claim 4 or 6, characterized in that: Viewed from above the fusible alloy, the notch is rectangular, V-shaped, trapezoidal, or arc-shaped.
8. The thermosetting cutter according to claim 1, characterized in that: The minimum cross-sectional area of the welded area along the X-plane is greater than the minimum cross-sectional area of either the first or the second non-welded area along the X-plane.
9. The thermosetting cutter according to claim 1, characterized in that: It also includes a housing and a fluxing agent, the fluxing agent being located above the welding area on the surface of the fusible alloy away from the heating element; a cavity is formed inside the housing to accommodate the fluxing agent and the fusible alloy between the housing and the heating element.
10. A protection circuit, characterized in that: It includes multiple parallel-connected thermoplastic cutters, wherein the thermoplastic cutters are thermoplastic cutters as described in any one of claims 1-9; In all parallel thermoelectric cut-off devices, the total cross-sectional area of the first or second non-welded area near the current input side along the plane parallel to the X is greater than the total cross-sectional area of the second or first non-welded area near the current output side along the plane parallel to the X. Alternatively, in all parallel thermowelding cutters, the total cross-sectional area of the first or second non-welded area near the current input side along the X-plane is smaller than the total cross-sectional area of the second or first non-welded area near the current output side along the X-plane.