Temperature fuse with over-current protection function
By optimizing the resistance value of the temperature fuse electrode and selecting material, using the temperature resistance self-excitation effect, rapid response and protection when lithium-ion batteries are overcurrent is achieved, the problem of traditional fuses not responding in time is solved, and the heat generation and power consumption are maintained at low during normal operation.
Patent Information
- Application Number
- CN202421321176.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-11
- Publication Date
- 2025-03-25
- Estimated Expiration
- 2034-06-11
AI Technical Summary
Traditional alloy-type temperature fuses increase the temperature and transmit speed when lithium-ion batteries are overcurrent, resulting in failure to respond in time, which may cause the battery to catch fire or explode. At the same time, the current fuse resistance value of conventional small rated current value is large, resulting in excessive heat generation and excessive power consumption.
A temperature fuse with overcurrent protection function is designed, and by optimizing the resistance value of the electrode, the resistance value near the melting core side is high and the resistance value far away from the melting core side is low. Using high resistivity temperature coefficient material, the temperature resistance self-excitation effect is used to melt the melting core through its own temperature rise in the overcurrent state of small multiples, achieving rapid cut-off.
When working at rated current, the heating and power consumption are small and it works normally; in the overcurrent state of small multiples, it can respond quickly and achieve the disconnection of the melt core, providing dual protection of overcurrent and overtemperature.
Smart Images
Figure CN222672953U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of fuses, in particular to a temperature fuse with an overcurrent protection function. Background Art
[0002] Lithium-ion batteries have the advantages of high capacity density, high average output voltage, and fast charge and discharge. They are currently widely used in various small handheld electronic devices. Due to the inherent characteristics of lithium-ion batteries, if overcharge, overdischarge or overcurrent occurs during the charging or discharging process, the battery temperature will rise sharply, causing battery damage or even explosion. In order to improve the safety of the battery, lithium-ion batteries are usually equipped with a fuse. When overcurrent occurs, the fuse will cut off the battery circuit to avoid harm.
[0003] The insurance device of lithium-ion battery mainly adopts alloy type temperature fuse. Alloy type temperature fuse has been widely used in recent years because it cannot be reset after actuation, has high actuation temperature accuracy and high reliability. Conventional alloy type temperature fuse has built-in alloy type temperature sensor. When the external temperature is transferred to the alloy type temperature sensor and reaches its melting point, the alloy quickly shrinks to the pins on both sides with the help of the surface tension of the flux, causing the circuit to be cut off.
[0004] Traditional alloy-type temperature fuses work by sensing external temperature. When lithium-ion batteries are overcurrented, the temperature rises and is not transmitted to the temperature fuse quickly enough. There is a possibility that the temperature fuse fails to respond in time and the battery has caught fire or even exploded. In order to prevent lithium batteries from outputting excessive current for a long time, it is necessary to connect a current fuse in series in the circuit. However, conventional current fuses with small rated current values have large resistance values, which can lead to unfavorable conditions such as excessive heat generation and excessive power consumption. If the resistance value of the fuse is directly reduced, there is the problem that the heat generated in the case of small multiple overcurrent is too small to reach the melting temperature of the fuse core.
[0005] It should be noted that the information disclosed in this background technology section is only intended to increase the understanding of the overall background of the utility model, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to a person skilled in the art. Utility Model Content
[0006] The utility model provides a temperature fuse with an overcurrent protection function. The temperature fuse comprises a first electrode, a second electrode, a fuse core and a packaging layer. The first electrode has a first end and a second end opposite to each other, the second electrode has a third end and a fourth end opposite to each other, and the two sides of the fuse core are respectively connected to the first electrode and the second electrode. The packaging layer covers the fuse core, the first electrode and the second electrode. Among them, the first end of the first electrode is closer to the fuse core than the second end, and the third end of the second electrode is closer to the fuse core than the fourth end. The first electrode has a first resistance value and a second resistance value at the first end and the second end, respectively, and the second electrode has a third resistance value and a fourth resistance value at the third end and the fourth end, respectively, the first resistance value is greater than the second resistance value, and the third resistance value is greater than the fourth resistance value.
[0007] Furthermore, the first electrode and the second electrode are made of a material with a high temperature coefficient of resistivity, and the temperature coefficient of resistivity of the first electrode and the second electrode is ≥0.003aR / °C.
[0008] Furthermore, the first resistance is equal to the third resistance.
[0009] Furthermore, looking down from the top of the temperature fuse toward the fuse core, the first width of the first electrode at the first end is smaller than the second width of the first electrode at the second end, and the third width of the second electrode at the third end is smaller than the fourth width of the second electrode at the fourth end.
[0010] Furthermore, a cross-sectional area of the first electrode at the first end is smaller than a cross-sectional area of the first electrode at the second end, and a cross-sectional area of the second electrode at the third end is smaller than a cross-sectional area of the second electrode at the fourth end.
[0011] Furthermore, the cross-sectional area of the first electrode at the first end is smaller than half of the cross-sectional area of the first electrode at the second end, and the cross-sectional area of the second electrode at the third end is smaller than half of the cross-sectional area of the second electrode at the fourth end.
[0012] Furthermore, the first resistance is at least twice the second resistance, and the third resistance is at least twice the fourth resistance.
[0013] Furthermore, the temperature fuse also includes a flux structure, the flux structure covers the fuse core, and the encapsulation layer covers the flux structure.
[0014] Furthermore, the first electrode has a first inclined surface at the first end, and the second electrode has a second inclined surface at the third end.
[0015] Furthermore, through holes are provided on the first end and the third end; the end face of the through hole on the first end away from the second end is flush with the end face of the first end or has a certain distance, and the end face of the through hole on the third end away from the fourth end is flush with the end face of the third end or has a certain distance.
[0016] Furthermore, the minimum distance between the first electrode and the second electrode is ≥0.3 mm.
[0017] Furthermore, the connection mode between the fuse core and the first electrode is butt joint or overlap joint, and the connection mode between the fuse core and the second electrode is butt joint or overlap joint.
[0018] Furthermore, the encapsulation layer is a shell, and the material of the shell includes UV resin.
[0019] The utility model provides a temperature fuse with overcurrent protection function. By optimizing the resistance of the electrode, the resistance of the side close to the fuse core is high, and the resistance of the side far from the fuse core is low. On the basis of overtemperature protection, the temperature fuse can generate less heat and power consumption when working under the rated current, and work normally; it can also melt the fuse core by increasing its own temperature rise under the overcurrent state of small multiples, so that the fuse core is disconnected. Specifically, when the working current passes normally, although the heat generation of the side with high resistance is slightly higher than that of the surrounding, it can be dissipated by conducting heat to the outside through the electrode, and the whole fuse is still in a suitable temperature state. When the overcurrent is small multiples, because the electrode has a large resistivity temperature coefficient, the heat generated by the overcurrent is partially dissipated to the surrounding area (such as dissipating to the PCB board and alloy), and the remaining heat increases its own temperature, thereby increasing its own resistivity. After the resistivity increases, more heat is generated, and the heat is further dissipated to the surrounding area, forming a temperature resistance self-excitation effect, so that the fuse relies on its own heating to achieve rapid disconnection and rapid response to overcurrent abnormal industrial control. At the same time, the alloy temperature sensor can sense the external ambient temperature. When the ambient temperature is too high, it will operate and cut off the circuit to achieve dual protection against over-current and over-temperature.
[0020] Other features and beneficial effects of the utility model will be described in the subsequent description, and some of the technical features and beneficial effects can be obviously derived from the description, or can be understood by implementing the utility model. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the embodiments of the utility model 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, some of the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0022] Figure 1A It is a schematic diagram of the structure of the thermal fuse provided by the first embodiment of the utility model;
[0023] Figure 1B yes Figure 1A Explosion diagram of
[0024] Figure 2 It is a schematic diagram of the top view of the thermal fuse provided by the first embodiment of the utility model;
[0025] Figure 3A It is a schematic diagram of the structure of a thermal fuse provided by the second embodiment of the utility model;
[0026] Figure 3B yes Figure 3A Explosion diagram of
[0027] Figure 4 It is a schematic diagram of the top view of the thermal fuse provided by the third embodiment of the utility model;
[0028] Figure 5 It is a schematic diagram of the top view of the thermal fuse provided by the fourth embodiment of the utility model;
[0029] Figure 6 1 is a schematic diagram of a top view of a thermal fuse provided in a fifth embodiment of the present utility model;
[0030] Figure 7 It is a schematic diagram of the top view of the thermal fuse provided by the sixth embodiment of the utility model.
[0031] Reference numerals:
[0032] 10-first electrode; 101-first end; 102-second end; 103-first structure; 104-second structure; 20-second electrode; 201-third end; 202-fourth end; 203-third structure; 204-fourth structure; 30-fusible core; 40-fluxing structure; 50-encapsulation layer; 60-thin film layer; W1-first width; W2-second width; W3-third width; W4-fourth width. DETAILED DESCRIPTION
[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all of the embodiments; the technical features designed in different implementation modes of the utility model described below can be combined with each other as long as they do not conflict with each other; based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.
[0034] In the description of the present utility model, it should be understood that the terms "center", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more. In addition, the term "including" and any variation thereof all mean "at least including".
[0035] See also Figure 1A , Figure 1B and Figure 2 , Figure 1A It is a schematic diagram of the structure of the temperature fuse provided by the first embodiment of the utility model. Figure 1B yes Figure 1A Schematic diagram of the explosion, Figure 2 1 is a schematic diagram of the top view of the thermal fuse provided by the first embodiment of the utility model. It should be noted that: Figure 2 The flux structure 40 and the encapsulation layer 50 are omitted. Figure 2 The relationship among the first electrode 10 , the second electrode 20 and the fuse 30 is mainly illustrated.
[0036] To achieve at least one of the above advantages or other advantages, the first embodiment of the present invention provides a thermal fuse with overcurrent protection function. As shown in the figure, the thermal fuse includes a first electrode 10, a second electrode 20 and a fuse core 30, a flux structure 40 and an encapsulation layer 50.
[0037] The first electrode 10 has a first end 101 and a second end 102 relative to each other. The second electrode 20 has a third end 201 and a fourth end 202 relative to each other. Taking the figure as an example, the first end 101 is the right end of the first electrode 10, the second end 102 is the left end of the first electrode 10, the third end 201 is the left end of the second electrode 20, and the fourth end 202 is the right end of the second electrode 20. The first electrode 10 and the second electrode 20 can use a metal with a larger temperature coefficient of resistivity, so that when the temperature rises, the resistivity of the electrode is also higher, and the more heat is generated after the current passes. Optionally, the temperature coefficient of resistivity of the first electrode 10 and the second electrode 20 is ≥0.003aR / ℃. Optionally, the materials of the first electrode 10 and the second electrode 20 include nickel, cobalt, silver, copper, gold and alloys or composite metal materials thereof, that is, the alloys and composite metal materials can be alloys and composite metal materials including at least one of nickel, cobalt, silver, copper, gold, etc. Preferably, the materials of the first electrode 10 and the second electrode 20 are nickel and its alloys or composite materials. The nickel material has a high temperature coefficient of resistivity and the best self-excitation effect of temperature resistance. This self-excitation effect effectively ensures that the overcurrent protection temperature fuse is safely turned on under normal working current. When there is an overcurrent, the temperature on one side close to the fuse 30 rises significantly, and the fuse 30 is quickly cut off with the help of the flux after being heated.
[0038] The two sides of the fusible core 30 are connected to the first electrode 10 and the second electrode 20 respectively, that is, the connection mode between the fusible core 30 and the first electrode 10 and the second electrode 20 is butt joint. The fusible core 30 can be made of fusible alloy. In this embodiment, the first electrode 10 and the second electrode 20 are arranged symmetrically, the two electrodes are arranged horizontally, and the fusible core 30 is welded between the first electrode 10 and the second electrode 20.
[0039] The flux structure 40 covers the fusible core 30. The flux structure 40 uses a flux cutter, and the surface tension of the flux cutter helps the fusible core 30 to quickly shrink toward the electrodes on both sides when it melts, thereby cutting off the circuit. The encapsulation layer 50 covers the flux structure 40, part of the first electrode 10 and part of the second electrode 20, and can provide encapsulation protection. The material of the encapsulation layer 50 can include UV glue, resin, etc. In some embodiments, the flux structure 40 may not be provided, and the fusible core 30 is covered by the encapsulation layer 50. In some embodiments, the encapsulation layer 50 is a shell, and the material of the shell may include UV resin.
[0040] The first end 101 of the first electrode 10 is closer to the fuse 30 than the second end 102, and the third end 201 of the second electrode 20 is closer to the fuse 30 than the fourth end 202. The first electrode 10 has a first resistance and a second resistance at the first end 101 and the second end 102, respectively, and the second electrode 20 has a third resistance and a fourth resistance at the third end 201 and the fourth end 202, respectively. By optimizing the resistance of the electrodes, the first resistance is greater than the second resistance, and the third resistance is greater than the fourth resistance, that is, the resistance of the electrode 10 / 20 close to the fuse 30 is high, and the resistance of the side away from the fuse 30 is low, so that the temperature fuse can work normally with less heat and power consumption when working under the rated current on the basis of over-temperature protection; it can also melt the fuse 30 by increasing its own temperature rise under a small multiple of over-current state, so that the fuse 30 is disconnected. Specifically, when the working current passes normally, although the heat generated by the side with high resistance is slightly higher than the surrounding area, it can dissipate heat through the electrode to the outside, and the entire fuse is still in a suitable temperature state. When the overcurrent is small, because the electrode has a large temperature coefficient of resistivity, the heat generated by the overcurrent is partially dissipated to the surrounding area (such as to the PCB board and alloy), and the remaining heat will increase its own temperature, thereby increasing its own resistivity. After the resistivity increases, more heat is generated, and the heat is further dissipated to the surrounding area, forming a temperature resistance self-excitation effect, so that the fuse can quickly cut off by its own heating and quickly respond to overcurrent abnormal industrial control. Due to the presence of the temperature sensor of the fuse core 30, the fuse can also sense the external ambient temperature and act, and has dual protection effects of overcurrent and overtemperature.
[0041] In some embodiments, when looking down from the top of the temperature fuse toward the fuse core 30, the first width W1 of the first electrode 10 at the first end 101 is smaller than the second width W2 of the first electrode 10 at the second end 102, and the third width W3 of the second electrode 20 at the third end 201 is smaller than the fourth width W4 of the second electrode 20 at the fourth end 202. With this arrangement, a narrow diameter structure is formed in the area with a smaller width, so that the cross-sectional area at the narrow diameter position is reduced, the resistance is increased, and the heat is increased, which helps to make the fuse quickly blow when there is a small multiple of overcurrent, and quickly respond to overcurrent abnormal industrial control. Optionally, the second width W2 is at least 1.1 times the first width W1, and the fourth width W4 is at least 1.1 times the third width W3. In some embodiments, the resistance value at the narrow diameter structure accounts for more than 30% of the resistance value of the electrode where it is located.
[0042] In some embodiments, the cross-section of the first end 101 of the first electrode 10 and the third end 201 of the second electrode 20 may be an "I" shape, that is, the first width W1 and the third width W3 are variable values. Optionally, the first width W1 may be the minimum width at the first end 101 of the "I" shape, and the third width W3 may be the minimum width at the third end 201 of the "I" shape. This is not shown in the figure.
[0043] Furthermore, since the first electrode 10 and the second electrode 20 have a certain thickness, the cross-sectional areas of the two electrodes in the length direction are not the same (such as an "I"-shaped electrode), and the performance of the fuse to quickly cut off by relying on its own heating can be improved by reducing the cross-sectional areas of the first end 101 and the third end 201. In other words, by making the cross-sectional area of the first electrode 10 at the first end 101 smaller than the cross-sectional area of the first electrode 10 at the second end 102, and the cross-sectional area of the second electrode 20 at the third end 201 smaller than the cross-sectional area of the second electrode 20 at the fourth end 202, the performance of the fuse to quickly cut off by relying on its own heating can be improved, and a rapid response to overcurrent abnormal industrial control can be achieved. Optionally, the cross-sectional area of the first electrode 10 at the first end 101 is smaller than half of the cross-sectional area of the first electrode 10 at the second end 102, and the cross-sectional area of the second electrode 20 at the third end 201 is smaller than half of the cross-sectional area of the second electrode 20 at the fourth end 202. It should be noted that the cross-sectional area is a cross-sectional area perpendicular to the direction of current flow, which can be a cross-sectional area of the first electrode 10 at the third end 201. Figure 2 On this basis, a section line is made along the width direction to obtain the cross section.
[0044] In some embodiments, the first resistance is equal to the third resistance, so that the temperature of the first electrode 10 and the second electrode 20 at one end close to the fuse 30 can rise synchronously as much as possible to avoid overheating. In some embodiments, the first resistance is at least twice the second resistance, and the third resistance is at least twice the fourth resistance.
[0045] In some embodiments, when looking down from the top of the temperature fuse toward the fuse core 30, the area of the first end 101 accounts for 5% to 35% of the area of the first electrode 10; the area of the third end 201 accounts for 5% to 35% of the area of the second electrode 20, thereby improving the performance of the fuse to achieve rapid cutting off by relying on its own heat, and realizing rapid response to overcurrent abnormal industrial control.
[0046] In some embodiments, to ensure that the fuse core 30 can be safely blown, the minimum distance between the first electrode 10 and the second electrode 20 is ≥0.3 mm.
[0047] Further, through holes are provided on the first end 101 and the third end 201. The end surface of the through hole on the first end 101 away from the second end 102 is flush with the end surface of the first end 101 or has a certain distance, and the end surface of the through hole on the third end 202 away from the fourth end 202 is flush with the end surface of the third end 201 or has a certain distance. In the illustrated embodiment, the right end surface of the through hole on the first end 101 is flush with the end surface of the first end 101, and the left end surface of the through hole on the third end 201 is flush with the end surface of the third end 201.
[0048] See also Figure 3A and Figure 3B , Figure 3A is a schematic diagram of the structure of a temperature fuse provided by a second embodiment of the present invention, Figure 3B yes Figure 3A Schematic diagram of the explosion. Figure 1A As for the temperature fuse shown in the figure, the difference of this embodiment is mainly that the connection mode of the fuse core 30 and the first electrode 10 and the second electrode 20 is overlapped. That is, the fuse core 30 is arranged on the first electrode 10 and the second electrode 20, and the flux structure 40 is encapsulated by the film layer 60, that is, the encapsulation layer 50 here adopts the film layer 60, and the upper and lower edges of the film layer 60 are welded by hot pressing or ultrasonic welding to make the inside in a sealed state. In addition, a film layer 60 composite or coated with hot melt adhesive can also be used to achieve rapid encapsulation at low temperature.
[0049] See also Figure 4 , Figure 4 Schematic diagram of the top view of the thermal fuse provided by the third embodiment of the utility model. Figure 2 As for the temperature fuse shown in the figure, the difference of this embodiment is mainly that the fuse core 30 is overlapped on the first electrode 10 and the second electrode 20, which is more convenient for welding.
[0050] See also Figure 5 , Figure 5 Schematic diagram of the top view of the thermal fuse provided by the fourth embodiment of the utility model. Figure 2 As for the temperature fuse shown in FIG. 1 , the difference of this embodiment is mainly that the through holes on the first electrode 10 and the second electrode 20 are not connected to the fuse core 30. That is, the end face of the through hole on the first end 101 away from the second end 102 is spaced apart from the end face of the first end 101, and the end face of the through hole on the third end 202 away from the fourth end 202 is spaced apart from the end face of the third end 201.
[0051] See also Figure 6 , Figure 6 Schematic diagram of the top view of the thermal fuse provided by the fifth embodiment of the utility model. Figure 2As for the temperature fuse shown in FIG. 1 , the difference of this embodiment is mainly that: the first electrode 10 has a first inclined surface at the first end 101, the second electrode 20 has a second inclined surface at the third end 201, and the fuse 30 also has an inclined surface. By designing the inclined surface, the cross-sectional area of the fuse 30 is increased, the resistance of the fuse 30 is reduced, and thus the total resistance of the fuse is reduced. Of course, in other embodiments, the resistance of the fuse 30 can also be reduced by increasing the width of the fuse 30 perpendicular to the current direction.
[0052] See also Figure 7 , Figure 7 Schematic diagram of the top view of the thermal fuse provided by the sixth embodiment of the utility model. Figure 2 As for the temperature fuse shown in the figure, the difference of this embodiment is mainly that: the first electrode 10 forms a first structure 103 and a second structure 104 at the first end 101 and the second end 102, respectively, and the second electrode 20 forms a third structure 203 and a fourth structure 204 at the third end 201 and the fourth end 202, respectively. The first electrode 10 and the second electrode 20 are made of composite materials, the first end 101 and the third end 201 are high resistivity materials, and the second end 102 and the fourth end 202 are low resistivity materials, that is, compared with the material of the first structure 103 and the material of the second structure 104, the material of the first structure 103 is a high resistivity material, and the material of the second structure 104 is a low resistivity material. Compared with the material of the third structure 203 and the material of the fourth structure 204, the material of the third structure 203 is a high resistivity material, and the material of the fourth structure 204 is a low resistivity material. For example, nickel is used as the high resistivity material and copper is used as the low resistivity material. However, the present invention is not limited thereto. The high resistivity material and the low resistivity material are relative to each other. It is only necessary to ensure that the resistivity of the high resistivity material is higher than that of the low resistivity material.
[0053] An embodiment of the present invention also provides a method for preparing a thermal fuse, which comprises the following steps:
[0054] S110: punching out the first electrode 10 and the second electrode 20 on the carrier tape, wherein the first electrode 10 and the second electrode 20 are designed to have a narrow diameter structure on one side close to the fuse core 30 .
[0055] S120: Welding the molten core 30 at the end between the first electrode 10 and the second electrode 20 by laser welding, resistance welding, thermal welding or other processes.
[0056] S130: forming a layer of flux on the surface of the fuse core 30 by coating, spraying or screen printing.
[0057] S140: After the flux is cooled and formed, the overall structure (the overall structure includes the flux, the first electrode 10, the second electrode 20 and the fuse 30) is sent into a transparent mold through a carrier tape.
[0058] S150: The transparent mold gate is injected with light-curing glue, and UV light passes through the transparent mold to cure the glue into shape.
[0059] S160: After light curing, demoulding is carried out, the fuse and carrier are cut and separated, and then packaged and put into storage after marking and testing.
[0060] An embodiment of the present invention further provides a method for preparing a thermal fuse, which comprises the following steps:
[0061] S210: punching out a plurality of pairs of first electrodes 10 and second electrodes 20 on the carrier tape, wherein the first electrodes 10 and the second electrodes 20 are designed to have a narrow diameter structure on one side close to the fuse 30, and the two electrodes are completely cut off from the carrier tape, and the two electrodes after punching are positioned on the first material tray.
[0062] S220: The molten core 30 is formed into slices and loaded onto a second material tray through a flexible tray or online slicing process.
[0063] S230 : buckle the first material tray and the second material tray, push the sliding block of the second material tray, so that the molten core 30 falls between the first electrode 10 and the second electrode 20 .
[0064] S240: welding the molten core 30 to the ends of the first electrode 10 and the second electrode 20 by using laser welding, resistance welding, thermal welding or other processes.
[0065] S250: forming a layer of flux on the surface of the fuse core 30 by coating, spraying or screen printing.
[0066] S260: After the flux is cooled and formed, the overall structure on the material tray (the overall structure includes the flux, the first electrode 10, the second electrode 20 and the fusible core 30) is transferred to the transparent mold bottom tray.
[0067] S270: Cover the transparent mold upper plate, inject light-curing glue through the gate, and UV light passes through the transparent mold to cure the glue into shape.
[0068] S280: After light curing, demoulding is carried out, and finally after marking, testing and other operations, the product is packaged and put into storage.
[0069] In some embodiments, the fuse core 30 coated with the flux and the ends of the two electrodes 10 / 20 are wrapped with a light-curing resin through a molding casting process, and the mold is made of a transparent material, and UV light passes through the mold to cure the resin inside. The mold material can be Teflon, silicone, etc. That is, the material of the transparent mold includes Teflon or silicone.
[0070] In some embodiments, the fusible core 30 and the flux can be packaged using a film layer, and the edges of the upper and lower film layers are welded by heat pressing or ultrasonic welding to make the inside of the two layers in a sealed state; or, a film layer composite or coated with hot melt adhesive is used to package in a low temperature environment. Furthermore, the connection method of the fusible core 30 and the first electrode 10 and the second electrode 20 can be butt joint or overlap joint, and the overlap joint method is preferred in the case of low thickness.
[0071] In summary, the utility model provides a temperature fuse with overcurrent protection function, which optimizes the resistance of the electrode so that the resistance of the side close to the fuse 30 is high and the resistance of the side away from the fuse 30 is low, so that the temperature fuse can work normally under the rated current with low heat and power consumption on the basis of over-temperature protection; it can also melt the fuse 30 by increasing its own temperature rise under the overcurrent state of small multiples, so that the fuse 30 is disconnected. Specifically, when the working current passes normally, although the heat generated by the side with high resistance is slightly higher than the surrounding, it can be dissipated by conducting heat to the outside through the electrode, and the whole fuse is still in a suitable temperature state. When the overcurrent is small, because the electrode has a large resistivity temperature coefficient, the heat generated by the overcurrent is partially dissipated to the surrounding area (such as dissipating to the PCB board and alloy), and the remaining heat increases its own temperature, thereby increasing its own resistivity. After the resistivity increases, more heat is generated, and the heat is further dissipated to the surrounding area, forming a temperature resistance self-excitation effect, so that the fuse relies on its own heating to achieve rapid disconnection and rapid response to overcurrent abnormal industrial control.
[0072] 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 utility model 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.
[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.
Claims
1. A thermal fuse with overcurrent protection function, characterized in that: The thermal fuse comprises: a first electrode having opposing first and second ends; a second electrode having opposing third and fourth ends; A fusible core, two sides of which are respectively connected to the first electrode and the second electrode; an encapsulation layer, covering the fuse core, a portion of the first electrode, and a portion of the second electrode; Among them, the first end of the first electrode is closer to the fuse core than the second end, the third end of the second electrode is closer to the fuse core than the fourth end, the first electrode has a first resistance value and a second resistance value at the first end and the second end respectively, the second electrode has a third resistance value and a fourth resistance value at the third end and the fourth end respectively, the first resistance value is greater than the second resistance value, and the third resistance value is greater than the fourth resistance value.
2. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The temperature coefficient of resistivity of the first electrode and the second electrode is ≥0.003aR / °C.
3. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The first resistance is equal to the third resistance.
4. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: Looking down from the top of the temperature fuse toward the fuse core, the first width of the first electrode at the first end is smaller than the second width of the first electrode at the second end, and the third width of the second electrode at the third end is smaller than the fourth width of the second electrode at the fourth end.
5. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The cross-sectional area of the first electrode at the first end is smaller than the cross-sectional area of the first electrode at the second end, and the cross-sectional area of the second electrode at the third end is smaller than the cross-sectional area of the second electrode at the fourth end.
6. The thermal fuse with overcurrent protection function according to claim 5, characterized in that: The cross-sectional area of the first electrode at the first end is smaller than half of the cross-sectional area of the first electrode at the second end, and the cross-sectional area of the second electrode at the third end is smaller than half of the cross-sectional area of the second electrode at the fourth end.
7. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The first resistance is at least twice the second resistance, and the third resistance is at least twice the fourth resistance.
8. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The temperature fuse further includes a flux structure, the flux structure covers the fuse core, and the packaging layer covers the flux structure.
9. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The first electrode has a first inclined surface at the first end, and the second electrode has a second inclined surface at the third end.
10. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: Through holes are provided on the first end and the third end; the end face of the through hole on the first end away from the second end is flush with or has a certain distance from the end face of the first end, and the end face of the through hole on the third end away from the fourth end is flush with or has a certain distance from the end face of the third end.
11. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The minimum distance between the first electrode and the second electrode is ≥0.3 mm.
12. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The connection mode of the fusible core and the first electrode is butt joint or overlap joint, and the connection mode of the fusible core and the second electrode is butt joint or overlap joint.
13. The thermal fuse with overcurrent protection function according to claim 1, characterized in that: The packaging layer is a shell, and the material of the shell includes UV resin.