Medium-high voltage DC temperature fuse

Abstract

This invention relates to the field of circuit fuse technology, and particularly to a medium- and high-voltage DC temperature fuse, which includes a housing, a main circuit, a tripping mechanism, an arc-extinguishing circuit, and a cutter disposed within the housing. The tripping mechanism is used to cut off the main circuit conduction when a preset operating temperature is reached. The arc-extinguishing circuit is connected in parallel to the main circuit and includes a first fuse and a second fuse connected in series with different fusing characteristics. The cutter is located on the movement trajectory of the tripping mechanism. The tripping mechanism cuts off the main circuit to form a double break when the temperature is too high, thereby weakening the arc-initiating conditions. At the same time, the different fusing characteristics of the first fuse and the second fuse are used to achieve graded arc extinguishing. Under low current or no current conditions, the arc-extinguishing circuit is mechanically forcibly cut off by the cutter linked by the slider, thereby achieving reliable interruption across the entire current range, from no-load to rated short-circuit current, covering various fault conditions such as overload, short circuit, and no-load over-temperature, thus expanding the product's applicable scenarios.

Description

Technical Field

[0001] This invention relates to the field of circuit fuse technology, and in particular to a medium- and high-voltage DC temperature fuse. Background Technology

[0002] A thermal fuse, as an over-temperature protection element, quickly cuts off the circuit when the protected electronic device overheats due to an abnormal fault, reaching the fuse's melting point to protect the circuit. However, when thermal fuses are used in medium- to high-voltage DC circuits, because DC current lacks a natural zero-crossing point, the sensing element gradually melts as it absorbs heat. The spring continuously releases until it pushes open the contact wire and the movable electrode. At the moment the contact wire and electrode separate, the voltage can easily break down the air medium, forming a continuous electric arc. This can cause the contact wire and the movable electrode to weld together directly, preventing the spring from pushing the movable electrode open and resulting in the thermal fuse's protective function failing.

[0003] To address this challenge, some existing thermal fuses incorporate parallel arc-extinguishing circuits at both ends. After the thermal fuse melts, current flows to the arc-extinguishing circuit, which then melts, thus improving the arc-extinguishing effect. Conventional thermal fuses are mostly used in low-voltage AC applications, limiting their application range, and their DC breaking speed needs to be improved.

[0004] It should be noted that the information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] To address the technical problem of existing thermal fuses being prone to disconnection failure due to electric arcing in medium and high voltage DC scenarios, this invention provides a medium and high voltage DC thermal fuse, which includes: case; The main circuit is located inside the housing; A tripping mechanism is used to cut off the conduction of the main circuit along a preset trajectory when the temperature reaches a preset operating temperature; An arc-extinguishing circuit is connected in parallel with the main circuit, and the arc-extinguishing circuit includes at least a first fuse and a second fuse connected in series and having different fusing characteristics. It also includes a cutter, which corresponds to the first fuse and / or the second fuse, and the cutter is located on the movement trajectory of the tripping mechanism.

[0006] Based on the above, the medium- and high-voltage DC temperature fuse provided by the present invention forms a double break by cutting off the main circuit when the temperature is too high through the tripping mechanism to weaken the arc initiation conditions. At the same time, it realizes graded arc extinguishing by utilizing the different fusing characteristics of the first fuse and the second fuse. Under low current or no current conditions, the arc extinguishing circuit is mechanically forcibly cut off by the slider linkage cutter, thereby realizing reliable interruption of the entire current range, that is, from no-load to rated short-circuit current, covering a variety of fault conditions such as overload, short circuit, no-load over-temperature, etc., and expanding the application scenarios of the product. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships in the drawings described below are based on the direction in which the components are drawn in the figures.

[0008] Figure 1 This is a schematic diagram of the structure of a medium-high voltage DC thermal fuse according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the exploded structure of a medium-high voltage DC thermal fuse according to an embodiment of the present invention; Figure 3 This is a top view schematic diagram of a medium-high voltage DC temperature fuse provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the main circuit and arc extinguishing circuit provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the slider provided in an embodiment of the present invention; Figure 6 This is an exploded view of the tripping mechanism provided in an embodiment of the present invention; Figure 7 , Figure 8 This is a schematic diagram of the assembly structure of the slider bolt and the linkage part from different perspectives according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of a drainage guide channel provided in an embodiment of the present invention; Figure 10 This is a schematic diagram of the arc extinguishing circuit provided in an embodiment of the present invention; Figure 11 for Figure 3 A magnified schematic diagram of the structure at point N.

[0009] Reference numerals: 10-House; 11-Top cover; 12-Base plate; 13-Drainage guide channel; 14-Shear groove; 141-Anti-detachment step; 20-Main circuit; 21-Intermediate electrode; 211-Limiting part; 22-First electrode; 23-Second electrode; 24-First spring; 25-Second spring; 26-Contact; 30-Triggering mechanism; 31-Slider; 311-Groove; 312-Stepped part; 313-Cone 32-First elastic element; 33-Limiting component; 331-Slider bolt; 3311-Protrusion; 3312-Step portion; 332-Second elastic element; 333-Linkage part; 3331-Blind hole; 334-Third elastic element; 335-Temperature sensor; 336-Protrusion; 40-Arc extinguishing circuit; 41-Connecting terminal; 42-First fuse; 43-Second fuse; 50-Cutter; 51-Anti-detachment protrusion Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0010] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Additionally, the term "comprising" and any variations thereof mean "at least comprising."

[0011] To address the technical problem of existing thermal fuses easily failing due to arcing in medium- and high-voltage DC scenarios, or to achieve at least one or more of the aforementioned advantages, an embodiment of the present invention provides a medium- and high-voltage DC thermal fuse. As shown in the figure, the thermal fuse includes... case; The main circuit is located inside the housing; A tripping mechanism is used to cut off the conduction of the main circuit along a preset trajectory when the temperature reaches a preset operating temperature; An arc-extinguishing circuit is connected in parallel with the main circuit, and the arc-extinguishing circuit includes at least a first fuse and a second fuse connected in series and having different fusing characteristics. It also includes a cutter, which corresponds to the first fuse and / or the second fuse, and the cutter is located on the movement trajectory of the tripping mechanism.

[0012] Furthermore, the main circuit includes a first electrode, a second electrode, and a bridging electrode. The bridging electrode consists of a first spring and a second spring disposed opposite to each other, and the first spring and the second spring are electrically connected to the first electrode and the second electrode, respectively. The main circuit also includes an intermediate electrode, which is disposed between the first reed and the second reed along a first direction, and contacts the first reed and the second reed respectively to form a contact and conduct electricity.

[0013] Furthermore, the tripping mechanism includes a slider, a first elastic element, and a limiting component. The slider is sleeved on the intermediate electrode, with one end of the slider abutting against the housing and the other end abutting against the contact point. The limiting component is engaged with the outer surface of the slider, and the limiting component has a second elastic element in a stored state built in it.

[0014] Furthermore, the end of the slider that abuts against the contact point has a conical structure.

[0015] Furthermore, the intermediate electrode is provided with a limiting part, the slider is provided with a stepped part, and the first elastic element is sleeved on the intermediate electrode, with one end abutting the limiting part and the other end abutting the stepped part in an energy storage state.

[0016] Furthermore, the outer surface of the slider is provided with a groove, and the limiting component is provided with a protrusion, which is embedded in the groove.

[0017] Furthermore, the limiting component includes a slider bolt, a linkage part, and a temperature sensor. The slider bolt is slidably disposed within the housing along a second direction for locking / releasing the slider. A protrusion is provided on the outer surface of both the slider bolt and the linkage part, and the two protrusions abut together and overlap at least in a third direction. The linkage part can slide relative to the slider bolt along the third direction for locking / releasing the slider bolt. The temperature sensor is positioned below the linkage part along the third direction. Wherein, the first direction, the second direction, and the third direction are perpendicular to each other in three-dimensional space.

[0018] Furthermore, the linkage part is provided with a blind hole, and a third elastic element is built into the blind hole. The third elastic element is placed between the linkage part and the housing and is in a compressed state; the other end of the linkage part abuts against the temperature sensing element.

[0019] Furthermore, the arc-extinguishing circuit also includes multiple connection terminals, and the first fuse and the second fuse are connected in series through the multiple connection terminals and then connected in parallel to the main circuit; The fusing cross-sectional area of ​​the first fuse is greater than that of the second fuse.

[0020] Furthermore, The housing is provided with a shearing groove, and the cutter is slidably disposed in the shearing groove. The inner wall of the shearing groove is provided with an anti-detachment step, and the side of the cutter is provided with an anti-detachment protrusion. The anti-detachment protrusion cooperates with the anti-detachment step. The cutting blade front end has a convex clearance structure, and the first fuse and / or the second fuse are placed inside the convex clearance structure; When the slider slides along the first direction to a preset stroke, it contacts the cutter and pushes the cutter to slide, thereby cutting off the first fuse and / or the second fuse.

[0021] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application and through various specific implementation methods.

[0022] Example 1 Please see Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of a medium-high voltage DC thermal fuse according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the exploded structure of a medium-high voltage DC thermal fuse according to an embodiment of the present invention.

[0023] As shown in the figure, the temperature fuse includes a housing 10, a main circuit 20, a tripping mechanism 30, and an arc-extinguishing circuit 40. The housing 10 serves as the mounting base for the overall structure, and has multiple positioning grooves and mounting cavities inside. Its upper and lower surfaces are respectively covered by an upper cover 11 and a base plate 12, which together form a closed protective cavity to accommodate and fix the various functional components.

[0024] Preferably, the housing 10 and the top cover 11 can be made of high-strength, high-insulation, and high-temperature resistant plastic materials, or ceramic materials, or metal and non-metal materials with effective surface insulation treatment, depending on the requirements.

[0025] The main circuit 20 is housed within the casing 10, serving as the core circuit for normal current carrying and disconnection. Please refer to... Figure 2 See Figure 4 , Figure 5 The main circuit 20 includes an intermediate electrode 21, a first electrode 22, and a second electrode 23. The intermediate electrode 21 is fixedly installed inside the housing 10 along a first direction (X), and its shape can be cylindrical, polygonal strip, or other structures. In this embodiment, the intermediate electrode 21 is preferably a flat rectangular strip structure, which is beneficial for forming a conductive circuit with low contact resistance.

[0026] The first electrode 22 and the second electrode 23 are symmetrically arranged on both sides of the intermediate electrode 21. The ends of the first electrode 22 and the second electrode 23 away from the intermediate electrode 21 extend outwards from the housing 10 to form terminals for connection to the protected circuit, while the ends facing the intermediate electrode 21 are respectively connected to bridging electrodes. In this embodiment, the bridging electrodes are preferably the first spring 24 and the second spring 25.

[0027] The first spring 24 and the second spring 25 can be made of materials such as beryllium copper, tin-phosphor bronze, or stainless steel plated with silver, possessing good elasticity and conductivity. They are riveted to the first electrode 22 and the second electrode 23 respectively using rivets or other methods. Contacts 26 are welded to the free ends of both the first spring 24 and the second spring 25. The contacts 26 can be tin-plated or silver-plated. In this embodiment, silver-plated contacts are preferred, which can effectively reduce contact resistance and decrease Joule temperature rise during normal operation.

[0028] When the main circuit 20 is turned on, the elastic preload of the first spring 24 and the second spring 25 can ensure stable contact between the contact 26 and the intermediate electrode 21, avoiding poor contact under vibration conditions. Of course, the contact 26 can also be welded to both sides of the intermediate electrode 21 to ensure stable circuit connection, and the melting point of the solder joint between the contact 26 and the intermediate electrode 21 should be lower than the melting point of the temperature sensor 335.

[0029] When the circuit malfunctions, the solder joint between contact 26 and intermediate electrode 21 melts, and under the push of tripping mechanism 30, contact 26 is disconnected from intermediate electrode 21.

[0030] Of course, it should be noted that the cross-sectional specifications of the intermediate electrode 21, the first electrode 22 and the second electrode 23 can be selected according to the rated current. This case does not impose any restrictions on this. For example, the design standard is that the temperature rise during normal operation should not exceed 25K, so as to avoid the normal current-carrying temperature rise triggering the temperature sensor to malfunction.

[0031] The tripping mechanism 30 includes a slider 31, a first elastic element 32, and a limiting component 33. The slider 31 and the first elastic element 32 are respectively sleeved on the intermediate electrode 21. The limiting component 33 is used to limit the slider 31 to remain in a locked state, and when a preset operating temperature is reached, the slider 31 is released to cut off the conduction of the main circuit 20.

[0032] In specific implementation, please combine Figure 2 See Figures 5-9 The slider 31 is fitted onto the intermediate electrode 21, with one end abutting against the housing 10 and the other end abutting against the contact 26. It can slide along the first direction guided by the intermediate electrode 21, serving as the direct execution component for disconnecting the main circuit 20.

[0033] like Figure 5 , Figure 6 As shown, the outer surface of the slider 31 is provided with a groove 311, which engages with the limiting component 33 to keep the slider 31 in a locked state. Preferably, the slider 31 can also be made of high-strength, high-insulation, high-temperature resistant plastic materials, ceramics, etc., which have good insulation properties to ensure that after breakage, the slider 31 body can withstand the voltage between the intermediate electrode 21 and the double breaks of the first electrode 22 and the second electrode 23, without penetrating breakdown.

[0034] Furthermore, the intermediate electrode 21 is provided with a limiting part 211, and the slider 31 is provided with a stepped part 312. When the first elastic member 32 is sleeved on the intermediate electrode 21, one end abuts against the limiting part 211 and the other end abuts against the stepped part 312, serving as a power source to push the slider 31 to slide along the first direction.

[0035] The first elastic element 32 can be made of highly elastic stainless steel and can be in the shape of a circular elastic element or a square spring. In this embodiment, a square spring is preferred, which is used in conjunction with a rectangular strip-shaped intermediate electrode 21 as a guide. Compared with a circular spring, the thrust axis of the square spring is more stable and will not generate torsional torque. The thrust can be applied evenly to the slider 31, reducing the lateral friction between the slider 31 and the intermediate electrode 21, improving the smoothness of sliding, and ensuring that the slider 31 can evenly push open the first spring 24 and the second spring 25, so as to achieve synchronous breaking of the two fracture surfaces. This avoids the problems of arc deviation and uneven pressure distribution caused by the separation delay on one side, improves the consistency of breaking, and achieves the purpose of pressure distribution and weakening the conditions for arc initiation. At the same time, the square spring can provide greater elastic force in the same volume, ensuring that the slider 31 has sufficient breaking speed and impact energy.

[0036] In a more preferred embodiment, the thrust of the first elastic element 32 is 15N, which ensures reliable breakage while taking into account the lifespan of the mechanism and the volume of the product.

[0037] When the slider 31 is in the locked state, the first elastic element 32 is in the energy storage state, and the first electrode 22 and the second electrode 23 respectively contact the intermediate electrode 21 to form a conductive circuit.

[0038] When the preset operating temperature is reached, the limiting component 33 releases the slider 31, which slides along the first direction guided by the intermediate electrode 21 under the elastic potential energy of the first elastic element 32. This squeezes the first spring 24 and the second spring 25 to separate from the intermediate electrode 21, cutting off the conduction of the main circuit 20. Simultaneously, the two contacts 26 separate from the intermediate electrode 21, forming a double electrical break. This ensures that the voltage at the moment of breakage is evenly distributed to the two breaks, with the pressure on a single break being only half of the rated voltage. The electric field strength between the breaks is reduced by 50% compared to the original voltage, thus weakening the arc-initiating conditions at the source and effectively reducing the probability and energy of arcing. The main circuit 20 is then cut off.

[0039] Preferably, the slider 31 forms a cone-shaped structure 313 facing the front ends of the first spring 24 and the second spring 25. Preferably, the angle α of the cone-shaped structure 313 is 120° to balance the overall size of the fuse and the resistance when the slider 31 breaks the main circuit 20.

[0040] Preferably, the width and wall thickness (the wall thickness between the intermediate electrode 21 and any one side contact 26) of the slider 31 can be designed to match the insulation withstand voltage of the material. Specifically, when the slider 31 is embedded in the relative area between the two contacts 26 after breaking the main circuit 20, the width of the slider 31 is greater than the product's preset safe creepage distance, and the wall thickness is sufficient to ensure that the slider 31 body can withstand the voltage between the intermediate electrode 21 and the first electrode 22, and between the intermediate electrode 21 and the second electrode 23 after the break, without causing a through-break.

[0041] Based on the above, such as Figures 6-9 As shown, the limiting component 33 includes a slider 331, a second elastic element 332, a linkage part 333, a third elastic element 334, and a temperature sensor 335.

[0042] In specific implementation, Figure 6 , Figure 7 Taking the sliding direction of slider 31 as an example, if the sliding direction of slider 31 is taken as the first direction (X), then slider bolt 331 is slidably disposed in the housing 10 along the second direction (Y) for locking / releasing slider 31. The second elastic member 332 is coaxially disposed between slider 31 and slider bolt 331, and the two ends of the second elastic member 332 abut against the housing 10 and slider bolt 331 respectively, for pushing slider bolt 331 to slide away from slider 31 along the second direction, so as to release slider 31 and cut off the conduction of main circuit 20.

[0043] The slider bolt 331 has a protrusion 3311 facing the slider 31 and corresponding to the groove 311. By inserting the protrusion 3311 into the groove 311, the slider 31 is limited and kept in a locked state. When the slider bolt 331 is pushed by the second elastic member 332, causing the protrusion 3311 to disengage from the groove 311, the slider 31 is released to perform a cutting action.

[0044] Preferably, such as Figure 8 As shown, the slider bolt 331 has a stepped portion 3312 below the end facing the slider 31, and the protrusion 3311 is engaged in the groove 311.

[0045] The temperature sensor 335 is located below the linkage part 333. Preferably, the linkage part 333 and the temperature sensor 335 are coaxially arranged along the third direction (Z). The outer surfaces of the slider bolt 331 and the linkage part 333 are each provided with a protrusion 336. When in the locked state, the two protrusions 336 are in contact with each other and overlap at least in the third direction.

[0046] The linkage 333 has a blind hole 3331 on the side away from the temperature sensor 335. The third elastic member 334 is located in the blind hole 3331 and its two ends abut against the upper cover 11 and the blind hole 3331 respectively, for pushing the linkage 333 to slide in a third direction.

[0047] Furthermore, the side of the temperature sensor 335 furthest from the linkage part 333 comes into contact with the base plate 12. The base plate 12 can be a metal material with effective surface insulation treatment, possessing good insulation and thermal conductivity, and is able to transfer the heat of the protected circuit to the temperature sensor 335.

[0048] In specific implementations, the temperature sensor 335 can be of organic or alloy type, and its shape can be designed in various forms such as cylinder, cube, cuboid, solid or hollow tube. This embodiment preferably uses a cylindrical structure. The temperature sensor 335 can be processed and formed through processes such as casting, injection molding, or extrusion: organic type temperature sensors can be made of polymer materials with stable melting temperatures, such as general organic materials, plastics, engineering plastics, and special plastics; alloy type temperature sensors can be made of fusible temperature-sensing alloy materials.

[0049] Better, such as Figure 9 As shown, the base plate 12 and the housing 10 together form a drainage channel 13 for the flow of the molten temperature sensor 335. This allows the temperature sensor 335 to melt and flow through the drainage channel 13 when the preset operating temperature is reached, triggering the tripping mechanism 30 to perform a cutting-off action, thereby cutting off the conduction of the main circuit 20 and achieving the purpose of circuit protection.

[0050] Under normal operating conditions, the temperature sensor 335 is in a solid state, supporting the linkage part 333 to compress the third elastic element 334 to store energy, and through the protrusion 336 on the outer surface of the linkage part 333 and the protrusion 336 on the outer surface of the slider bolt 331, it fits and engages with the second elastic element 332, so that the protrusion 3311 is embedded in the groove 311, restricting the sliding of the slider 31 and keeping the slider 31 in a locked state.

[0051] When the temperature reaches the preset operating temperature, the temperature sensor 335 absorbs heat and melts into a liquid state, losing its support for the linkage 333. Under the pushing force of the third elastic member 334, the linkage 333 slides downward along the third direction, squeezing the molten liquid into the drainage guide groove 13. After the linkage 333 moves downward, the protrusion 336 on its outer surface separates from the protrusion 336 on the outer surface of the slider bolt 331. Under the push of the second elastic member 332, the slider bolt 331 exits outward along the second direction, releasing the locking of the slider 31. The slider 31 then slides along the first direction under the elastic potential energy of the first elastic member 32, and the front cone structure 313 pushes open the contact between the first spring 24, the second spring 25 and the intermediate electrode 21 to cut off the conduction of the main circuit 20.

[0052] Better to, with Figure 6 Taking the example shown, the first direction, the second direction, and the third direction are perpendicular to each other in three-dimensional space. That is, the sliding direction of slider 31, the sliding direction of slider bolt 331, and the sliding direction of linkage 333 are perpendicular to each other in three-dimensional space, forming a three-axis orthogonal tripping linkage layout. This makes the motion vectors of each component independent of each other, and the driving force is transmitted along its own axis. There is no motion jamming caused by component forces. At the same time, the three actions are transmitted sequentially without action interference, ensuring the smoothness and response speed of the tripping process.

[0053] More preferably, to avoid the problem of false triggering of the tripping circuit due to aging and shrinkage of the temperature sensor 335, the overlap height h between the protrusion 336 on the outer surface of the linkage part 333 and the protrusion 336 on the outer surface of the slider bolt 331 in the third direction is not less than the height difference between the original height of the temperature sensor 335 and the height at which the tripping is triggered by melting, and not greater than the original height of the temperature sensor 335. For example, 1.5 mm. Of course, the overlap height h can be adjusted according to the actual selected temperature sensor 335, all within the protection scope of this application. Based on the above, in order to further enhance the arc extinguishing and breaking capability, an arc extinguishing circuit 40 is connected in parallel at both ends of the main circuit 20.

[0054] In specific implementation, combined with Figure 3 See Figure 10 , Figure 11The arc-extinguishing circuit 40 includes multiple connection terminals 41, a first fuse 42, and a second fuse 43. The multiple connection terminals 41 are respectively fixed on the housing 10. The first fuse 42 and the second fuse 43 are connected in series through the multiple connection terminals 41 and then connected in parallel between the first electrode 22 and the second electrode 23 to form an arc-extinguishing circuit 40 in parallel with the main circuit 20.

[0055] The first fuse 42 has a larger fusing cross-sectional area than the second fuse 43, meaning the diameter of the first fuse 42 is larger than the diameter of the second fuse 43, so that the first fuse 42 and the second fuse 43 have different fusing characteristics. Preferably, the surface of the second fuse 43 can be coated with arc-extinguishing paste to enhance the arc-extinguishing effect. Of course, the different fusing characteristics of the first fuse 42 and the second fuse 43 can also be achieved by adjusting their materials.

[0056] Under high current conditions, the arc-extinguishing circuit 40 adopts a graded fusing mechanism: At the instant the main circuit 20 is interrupted, the parallel arc-extinguishing circuit 40 provides a low-impedance freewheeling path for the current, rapidly transferring the current to the arc-extinguishing circuit 40. This significantly reduces the current value at the main circuit break, and combined with the voltage divider effect of the double break, further weakens the arc energy at the contact 26, fundamentally preventing the contact 26 from failing due to welding or breakage. At this time, the second fuse 43, with a smaller melting cross-sectional area, melts first due to concentrated Joule heat, interrupting the current for the first time and consuming some of the arc energy. The first fuse 42 melts after the second fuse 43, completing the secondary arc extinguishing, significantly reducing the arc energy of a single fuse and preventing a high-energy arc from breaking through the casing 10 or causing continuous arcing.

[0057] Under low current or no current conditions, after the main circuit 20 is disconnected, the Joule heat generated by the current flowing into the arc extinguishing circuit 40 is insufficient to make the second fuse 43 / first fuse 42 reach the melting temperature and melt on its own, which will cause the auxiliary circuit to continue to conduct and thus lose its protective function.

[0058] Therefore, the temperature fuse also includes a cutter 50. The cutter 50 is located on the movement trajectory of the slider 31. In a specific implementation, as... Figure 11 As shown, the housing 10 has a shearing groove 14 inside. The cutter 50 is slidably disposed in the shearing groove 14. The inner wall of the shearing groove 14 has an anti-detachment step 141. The side of the cutter 50 has an anti-detachment protrusion 51. The anti-detachment protrusion 51 cooperates with the anti-detachment step 141 to achieve anti-detachment and limit the cutter 50, so as to avoid the problem of the cutter 50 detaching or shifting.

[0059] Preferably, such as Figure 10 As shown, the front end of the cutter 50 has a convex clearance structure with an upward protrusion and a downward abutment. The first fuse 42 and / or the second fuse 43 pass through this convex clearance structure and are located below the protrusion.

[0060] When the slider 31 slides along the first direction to the preset stroke, the conical structure 313 will abut against the cutter 50 and push the cutter 50 to slide towards the first fuse 42 and / or the second fuse 43. The mechanical shearing force will force the first fuse 42 and / or the second fuse 43 to be cut off. In this way, under low current or no current conditions, the Joule heat generated by the current flowing into the arc extinguishing circuit 40 is insufficient to make the second fuse 43 / first fuse 42 reach the melting temperature and melt itself, thus cutting off the arc extinguishing circuit 40. This achieves reliable interruption across the entire current range, from no-load to rated short-circuit current, covering various fault conditions such as overload, short circuit, and no-load overheating, greatly expanding the product's applicable scenarios.

[0061] Preferably, the number of cutters 50 can be greater than one, and can be adjusted according to actual needs. The setting position can also be adjusted according to actual needs to ensure that the temperature fuse can safely cut off the arc extinguishing circuit after the main circuit is disconnected, even when there is a small current or no current.

[0062] Of course, it should be noted that when only one cutter 50 is set, the aforementioned "preset stroke" needs to be designed in conjunction with the diameters of the first fuse 42 and the second fuse 43 to ensure that under high current conditions, the second fuse 43 and the first fuse 42 melt before the slider 31 reaches the preset stroke. That is, when the cutter 50 is only set at the first fuse 42, the second fuse 43 melts before the first fuse 42 cuts; or when the cutter 50 is only set at the second fuse 43, the first fuse 42 cuts before the second fuse 43. By setting the disconnection sequence of the arc extinguishing circuit 40, the arc extinguishing effect can be further improved.

[0063] In another embodiment not specifically shown, the tripping mechanism 30 may not include the slider 31, but the first elastic element 32 directly abuts against the contact point 26; when the temperature sensing element 335 melts, the first elastic element 32 is released to push the first spring 24 and the second spring 25 to cut off the conduction of the main circuit 20, and pushes the cutter 50 to cut off the first fuse 42 and / or the second fuse 43 when the preset stroke is reached.

[0064] Example 2 This embodiment provides a method for assembling a thermal fuse, used for assembling the medium- and high-voltage DC thermal fuse described in the above embodiment, specifically including the following steps: Place the temperature sensor 335 into the receiving hole of the housing 10, and cover the bottom plate 12 so that the bottom plate 12 contacts the bottom surface of the temperature sensor 335. At the same time, the bottom plate 12 and the housing 10 enclose to form a drainage channel 13, thus completing the assembly of the temperature sensor 335. The first elastic element 32 and the slider 31 are sequentially placed on the intermediate electrode 21. Then the whole assembly is installed into the housing 10 in the first direction and fixed. The smoothness of the slider 31 is manually tested to ensure that there is no jamming. Insert the slider bolt 331, which is fitted with the second elastic element 332, into the corresponding position of the housing 10, and press the slider 31 to the designated locking position so that the protrusion 3311 is engaged in the groove 311; Insert the linkage 333 above the temperature sensor 335, so that the block 336 of the linkage 333 pushes the block 336 of the slider bolt 331 to keep it locked, and the bottom is completely in contact with the top surface of the temperature sensor 335. The overlap height h meets the design requirements. Then, put the third elastic element 334 into the blind hole 3331. The three connecting terminals 41 of the first fuse 42 and the second fuse 43 are installed into the housing 10, and the first fuse 42 and the second fuse 43 are in a taut state. The cutter 50 is installed in the position corresponding to the first fuse 42 and / or the second fuse 43. Arc extinguishing paste is applied to the second fuse 43 or the first fuse 42. The first electrode 22 riveted with the first spring 24 and the second electrode 23 riveted with the second spring 25 are respectively installed into the corresponding positions of the housing 10, so that the contact 26 on the first spring 24 and the contact 26 on the second spring 25 are respectively pressed into the intermediate electrode 21. After the top cover 11 is fitted onto the housing 10, ultrasonic welding is performed to seal the parts and complete the overall assembly.

[0065] In summary, the medium- and high-voltage DC temperature fuse provided by this invention forms a double break by cutting off the main circuit when the temperature exceeds the limit, thereby weakening the conditions for arc initiation. At the same time, it utilizes the different fusing characteristics of the first and second fuses to achieve graded arc extinguishing. Under low-current or no-current conditions, the arc extinguishing circuit is mechanically forcibly cut off by a slider-linked cutter, thereby achieving reliable interruption across the entire current range, from no-load to rated short-circuit current. This covers various fault conditions such as overload, short circuit, and no-load over-temperature, expanding the product's applicable scenarios.

[0066] Although this document uses terms such as main circuit and arc-extinguishing circuit frequently, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

[0067] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the 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.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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; and these 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 the present invention.

Claims

1. A medium- and high-voltage DC temperature fuse, characterized in that: include case; The main circuit is located inside the housing; A tripping mechanism is used to cut off the conduction of the main circuit along a preset trajectory when the temperature reaches a preset operating temperature; An arc-extinguishing circuit is connected in parallel with the main circuit, and the arc-extinguishing circuit includes at least a first fuse and a second fuse connected in series and having different fusing characteristics. It also includes a cutter, which corresponds to the first fuse and / or the second fuse, and the cutter is located on the movement trajectory of the tripping mechanism.

2. The medium- and high-voltage DC temperature fuse according to claim 1, characterized in that: The main circuit includes a first electrode, a second electrode, and a bridging electrode. The bridging electrode consists of a first spring and a second spring arranged opposite to each other. The first spring and the second spring are electrically connected to the first electrode and the second electrode, respectively. The main circuit also includes an intermediate electrode, which is disposed between the first reed and the second reed along a first direction, and contacts the first reed and the second reed respectively to form a contact and conduct electricity.

3. The medium- and high-voltage DC temperature fuse according to claim 2, characterized in that: The tripping mechanism includes a slider, a first elastic element, and a limiting component. The slider is sleeved on the intermediate electrode, with one end of the slider abutting against the housing and the other end abutting against the contact point. The limiting component is engaged with the outer surface of the slider, and the limiting component has a second elastic element in a stored state built in it.

4. The medium- and high-voltage DC temperature fuse according to claim 3, characterized in that: The end of the slider that abuts against the contact point has a conical structure.

5. The medium- and high-voltage DC temperature fuse according to claim 3, characterized in that: The intermediate electrode is provided with a limiting part, the slider is provided with a stepped part, and the first elastic element is sleeved on the intermediate electrode, with one end abutting the limiting part and the other end abutting the stepped part in an energy storage state.

6. The medium- and high-voltage DC temperature fuse according to claim 3, characterized in that: The outer surface of the slider is provided with a groove, and the limiting component is provided with a protrusion, which is embedded in the groove.

7. The medium- and high-voltage DC temperature fuse according to claim 6, characterized in that: The limiting component includes a slider bolt, a linkage part, and a temperature sensing element. The slider bolt is slidably disposed in the housing along a second direction for locking / releasing the slider. The outer surfaces of the slider bolt and the linkage part are each provided with a protrusion, and the two protrusions are abutted and overlap at least in a third direction. The linkage part can slide relative to the slider bolt along the third direction for locking / releasing the slider bolt. The temperature sensor is positioned below the linkage unit along the third direction; Wherein, the first direction, the second direction, and the third direction are perpendicular to each other in three-dimensional space.

8. The medium- and high-voltage DC temperature fuse according to claim 7, characterized in that: The linkage part is provided with a blind hole, and a third elastic element is built into the blind hole. The third elastic element is placed between the linkage part and the housing and is in a compressed state; the other end of the linkage part abuts against the temperature sensing element.

9. The medium- and high-voltage DC temperature fuse according to claim 1, characterized in that: The arc extinguishing circuit also includes multiple connection terminals. The first fuse and the second fuse are connected in series through the multiple connection terminals and then connected in parallel to the main circuit. The fusing cross-sectional area of ​​the first fuse is greater than that of the second fuse.

10. The medium- and high-voltage DC temperature fuse according to claim 1, characterized in that: The housing is provided with a shearing groove, and the cutter is slidably disposed in the shearing groove. The inner wall of the shearing groove is provided with an anti-detachment step, and the side of the cutter is provided with an anti-detachment protrusion. The anti-detachment protrusion cooperates with the anti-detachment step. The cutting blade front end has a convex clearance structure, and the first fuse and / or the second fuse are placed inside the convex clearance structure; When the slider slides along the first direction to a preset stroke, it contacts the cutter and pushes the cutter to slide, thereby cutting off the first fuse and / or the second fuse.

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