Excitation fuse with pressure reduction and exhaust structure

Abstract

The utility model relates to the field of circuit protection, in particular to an excitation fuse with a pressure reduction and exhaust structure, which comprises a shell, and an electronic ignition device, a piston, a conducting bar and a fuse structure which are sequentially positioned in a cavity of the shell, the fuse structure is connected to the conducting bar in parallel, a displacement channel penetrating through the two ends is formed in the fuse structure, and a melt cutter assembly is arranged in the displacement channel in a clearance fit mode; a melt of the fuse structure passes through the displacement channel and is located on a displacement path of the melt cutter assembly. A pressure relief airflow channel is arranged in the shell and communicated with a gap between the melt cutter assembly and the displacement channel. High-temperature and high-pressure gas generated by an electric arc when a melt is disconnected can be decompressed and cooled through the pressure relief gas flow channel, when the gas pressure is high enough after decompression and cooling, the high-pressure gas can be discharged to the outside of the shell through the exhaust port for decompression and cooling, and the strength requirement of the shell is reduced through decompression and cooling.

Description

Technical Field

[0001] The present invention belongs to the field of circuit protection, specifically relates to circuit protection in the fields of power control and electric vehicles, and more particularly refers to an excitation fuse with a pressure reduction and exhaust structure for circuit protection. Background Art

[0002] The main products for circuit overcurrent protection are thermal fuses and excitation fuses. Currently, there is an excitation fuse on the market and its application range is gradually expanding. The excitation fuse is a circuit protection structure that quickly cuts off the conductive bar to form an insulation break. Its general structure is as follows: Figure 1 : Electronic ignition device 101, upper shell 102, piston 103, sealing ring 104, conductive bar 105, melt 106, arc extinguishing medium 107, lower shell 108, melt upper cutter 109, melt lower cutter 110, melt protection shell 111, the upper shell cavity is arranged with the electronic ignition device and the piston from top to bottom, the conductive bar is arranged between the upper shell and the lower shell, and the melt, melt cutter assembly (melt upper cutter and melt lower cutter) and arc extinguishing medium are arranged in the lower shell; when disconnection is required, external force is used to first break the conductive bar and then disconnect the melt. The main problem is that there is no pressure reduction and exhaust channel for the high-temperature and high-pressure gas generated by the arc, which has a serious impact on disconnection.

[0003] Figure 1The working principle of the excitation fuse is as follows: the excitation fuse is connected in series in the circuit. When the vehicle is in normal working condition, the current flows through the conductive bar of the excitation fuse, and the product can be regarded as a conductor. When the fault current is small, the electronic ignition device is triggered by an electric signal to generate high-pressure gas, which first pushes the piston to break the weak part of the conductive bar to form a fracture. The fault current is completely transferred to the fuse connected in parallel with the conductive bar. Since the fault current is small, the heat generated at the narrow diameter of the melt is not enough to melt the narrow diameter and extinguish the arc. Therefore, the piston continues to move downward and then acts on the melt, so that the pre-break of the melt is completely interrupted in the arc extinguishing medium to achieve arc extinguishing; when the fault current is large, the electronic ignition device is triggered by an electric signal to generate high-pressure gas, which first pushes the piston to break the weak part of the conductive bar to form a fracture. The fault current is completely transferred to the melt connected in parallel with the conductive bar. Since the fault current is large, it passes through the narrow diameter of the melt. Heat is generated, and the narrow diameter of the melt begins to melt. At this time, the arc current decreases. As the piston continues to move downward, it acts on the melt again, causing the pre-break of the melt to be elongated in the arc extinguishing medium until it is broken. The arc length increases accordingly until the arc is extinguished. When the fault current is very large, the electronic ignition device is triggered by an electrical signal to generate high-pressure gas, which first pushes the piston to break the weak part of the conductive bar to form a fracture. The fault current is completely transferred to the melt in parallel with the conductive bar. Since the fault current is very large, a large amount of heat is generated at the narrow diameter of the melt, and the narrow diameter of the melt quickly melts. The arc extinguishing medium participates in extinguishing the arc, and the arc is quickly extinguished. Then the piston continues to move downward to break the pre-break of the melt, forming a physical fracture to ensure insulation after the fracture.

[0004] Although this excitation fuse has some improvements over thermal fuses and earlier excitation fuses that used air breaks to extinguish arcs, it also has the following shortcomings: the high temperature and high-pressure gas generated by the arc can easily cause the shell to crack, affecting disconnection and causing damage to surrounding equipment; to prevent the risk of cracking, it is necessary to increase the shell wall thickness or use higher-performance materials, which leads to increased costs. Summary of the Invention

[0005] The purpose of the present invention is to provide an excitation fuse with a pressure reducing and pressure relief exhaust structure, which adopts a pressure relief air flow channel designed for pressure reducing and pressure relief in the protective shell of the excitation fuse, so that the high-temperature and high-pressure gas pressure generated by the electric arc can reduce the pressure and temperature of the high-pressure gas through the pressure relief air flow channel to cool the electric arc; and the large volume space of the pressure relief air flow channel is utilized to achieve the function of reducing pressure and cooling the high-temperature and high-pressure gas.

[0006] To achieve the above objectives, the present invention provides a technical solution that is an excitation fuse with a pressure reducing and exhausting structure, comprising: a housing, and an electronic ignition device, a piston, a conductive bar, and a fuse structure sequentially located in a cavity of the housing; the fuse structure is connected in parallel to the conductive bar, a displacement channel is defined in the fuse structure, the displacement channel passes through both ends of the fuse structure in the displacement direction of the piston, and a melt cutter assembly is provided in the displacement channel in a clearance fit manner; the melt of the fuse structure passes through the displacement channel and is located on the displacement path of the melt cutter assembly; the electronic ignition device can release a driving force in response to a trigger signal, driving the piston to disconnect the conductive bar, and then driving the melt cutter assembly to disconnect the melt;

[0007] A pressure relief air flow channel is also provided in the housing, and the pressure relief air flow channel is communicated with the gap between the melt cutter assembly and the displacement channel.

[0008] Preferably, the pressure relief air flow channel is arranged between the two ends of the shell in the displacement direction of the piston and the melt disconnection assembly, and is located in the shell on the outer peripheral side of the cavity where the electronic ignition device, the piston and the fuse structure are located; a pressure relief gap is provided between the shell and one end of the fuse structure facing the end position of the melt cutter assembly, and the pressure relief gap is respectively communicated with one end of the pressure relief air flow channel facing the end position of the melt cutter assembly, and the gap between the displacement channel and the melt cutter assembly.

[0009] Preferably, at least one pressure relief cavity is further provided in the housing between the two ends of the housing in the displacement direction of the piston and the melt disconnect assembly and located on the outer peripheral side of the cavity where the electronic ignition device, the piston and the fuse structure are located, and the pressure relief cavity is connected to the pressure relief air flow channel.

[0010] Preferably, an exhaust port is provided on the outer side wall of the shell, and the exhaust port is communicated with an end of the pressure relief air flow channel away from the end position of the melt cutter assembly.

[0011] Preferably, the other end of the pressure relief air flow channel where the melt cutter assembly terminates is located in the housing outside the cavity where the electronic ignition device is located.

[0012] Preferably, a pressure relief valve is provided at the exhaust port.

[0013] Preferably, the pressure relief valve is a thin film structure, closing the exhaust port.

[0014] Preferably, the shell includes a first shell, a second shell, a third shell and a protective cover which are spliced ​​in sequence; the electronic ignition device is arranged in the first shell, the piston is arranged in the second shell, the fuse structure is arranged in the third shell, and the pressure relief gap is arranged between the fuse structure and the protective cover; the pressure relief airflow channel is arranged in the third shell, or in the third shell and the second shell, or in the third shell, the second shell and the first shell; at least one pressure relief cavity is provided in one of the first shell, the second shell and the third shell or in any two or more of them on one side of the pressure relief airflow channel.

[0015] Preferably, the pressure relief cavity is located on one or two end surfaces of the first shell, the second shell and the third shell, and the pressure relief cavity is formed by a pressure relief groove provided on the end surface.

[0016] Preferably, one end of the pressure relief air flow channel away from the protective cover and the exhaust port are respectively located on the end surface of the second shell facing the first shell, and the exhaust port is communicated with the pressure relief air flow channel.

[0017] Preferably, an accommodating groove is provided on the end face of the second shell facing the first shell, the first shell is arranged in the accommodating groove, and a pressure cover is provided on the end face of the first shell located outside the shell, and the pressure cover is connected to the second shell to fix the first shell; the pressure relief air flow channel extends to the end face of the second shell in contact with the pressure cover, and the pressure relief cavity is provided on the end face of the first shell facing the pressure cover, and a pressure relief gap is provided between the first shell and the pressure cover from the pressure relief cavity to the outer side face of the shell, and the pressure relief gap is respectively communicated with the pressure relief cavity and the pressure relief air flow channel provided on the end face of the first shell facing the pressure cover.

[0018] Preferably, a circle of annular pressure relief groove is provided at the end face of the second shell located outside the first shell facing the pressure cover, and the annular pressure relief groove is connected to the pressure relief airflow channel; the pressure relief cavity on the end face of the second shell facing the pressure cover, and the pressure relief cavity on the end face of the first shell facing the pressure cover, the pressure cover outside the first shell, the second shell and the pressure cover, and the second shell and the first shell are clearance fit.

[0019] Preferably, the shell is provided with bolt mounting holes that pass through both ends of the piston displacement direction, and the bolts are passed through the bolt mounting holes in a clearance fit manner to fix the shell; the pressure relief air flow channel or the pressure relief cavity is connected to the gap between the bolt mounting hole and the bolt.

[0020] Preferably, a cutter pushing device is provided between the fuse structure and the third shell, the melt cutter assembly protrudes from the fuse structure toward one end of the conductive row and forms a support for the cutter pushing device, and the cutter pushing device can be driven to move when the piston is displaced, and the cutter pushing device drives the melt cutter assembly to move.

[0021] Preferably, a buffer pad is provided in the pressure relief gap between the fuse structure and the protective cover, and the displacement channel is provided corresponding to the buffer pad.

[0022] The present invention includes a pressure relief airflow channel and a pressure relief cavity in the housing, so that the high-temperature, high-pressure gas generated by the arc is discharged into the pressure relief airflow channel and the pressure relief cavity through the gap between the melt cutter assembly and the displacement channel for decompression and cooling. The pressure of the high-temperature, high-pressure gas is rapidly reduced to a level that the plastic housing can withstand, and the gas temperature is also rapidly cooled to a safe range. In extreme cases, if the pressure of the gas after decompression is still too high and there is a possibility of damaging the housing, an exhaust port is added to the edge of the housing to discharge the cooled high-pressure gas outside the housing, thereby further reducing the pressure and venting the gas.

[0023] This invention ensures that the high-temperature, high-pressure gas pressure generated by the internal arc during interruption does not damage the overall structure of the excitation fuse. It also ensures that the high-temperature, high-pressure gas is properly decompressed, cooled, and, when necessary, discharged. This prevents arc leakage caused by decompression of the housing, as well as degradation of the internal insulation performance and creepage distance of the excitation fuse. It also reduces the design difficulty of the housing structure, lowers manufacturing costs, and enhances the fuse's interrupting performance and safety reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of an existing excitation fuse.

[0025] Figure 2 It is a structural schematic diagram of the present invention at the initial position.

[0026] Figure 3 yes Figure 2 Schematic diagram of the structure after the action.

[0027] Figure 4 yes Figure 3 Schematic diagram of gas flow after operation.

[0028] Figure 5 It is a schematic diagram of the three-dimensional appearance structure of one specific structure of the present invention.

[0029] Figure 6 yes Figure 5 Schematic diagram of the three-dimensional partial cross-sectional structure.

[0030] Figure 7 yes Figure 5 Schematic diagram of the cross-sectional structure viewed along the direction perpendicular to the conductive bar.

[0031] Figure 8 yes Figure 5 Schematic diagram of the cross-sectional structure along the length direction of the conductive bar.

[0032] Figure 9 It is a three-dimensional partial cross-sectional structural schematic diagram of another specific structure of the present invention.

[0033] Figure 10 yes Figure 9 Schematic diagram of the cross-sectional structure viewed along the direction perpendicular to the conductive bar.

[0034] Figure 11 yes Figure 9 Schematic diagram of the cross-sectional structure along the length direction of the conductive bar.

[0035] Reference numerals:

[0036] Electronic ignition device 101, upper housing 102, piston 103, sealing ring 104, conductive bar 105, melt 106, arc extinguishing medium 107, lower housing 108, melt upper cutter 109, melt lower cutter 110, melt protection shell 111;

[0037] Electronic ignition device 201, first housing 202, pressure relief groove 202a, piston 203, second housing 204, conductive bar 205, third housing 206, cutter pusher 207, melt 208, protective cover 209, melt lower cutter 210, melt protection shell 211, arc extinguishing medium 212, melt upper cutter 213, melt protection shell cover 214, pressure relief airflow channel 215, exhaust port 216;

[0038] Electronic ignition device 301, first housing 302, pressure relief groove 302a, piston 303, sealing ring 304, second housing 305, pressure relief groove 305a, conductive bar 306, cutter pusher 307, upper melt cutter 308, arc extinguishing cushion 309, arc extinguishing medium 310, lower melt cutter 311, protective cover 312, melt 313, melt protection shell 314, third housing 315, melt protection shell cover 316, pressure relief airflow channel 317, bolts 318, exhaust port 319;

[0039] Electronic ignition device 401, pressure cover 402, first shell 403, second shell 404, sealing ring 405, piston 406, conductive bar 407, third shell 408, melt protection shell 409, protective cover 410, arc extinguishing buffer pad 411, arc extinguishing medium 412, melt lower cutter 413, melt 414, melt upper cutter 415, cutter pushing device 416, melt protection shell cover 417, pressure relief air flow channel 418, annular pressure relief groove 419, tubular pressure relief groove 420, tubular pressure relief groove 421, exhaust port 422. DETAILED DESCRIPTION

[0040] The excitation fuse with a pressure reducing and exhausting structure of the present invention comprises: a housing, and an electronic ignition device, a piston, a conductive bar, and a fuse structure sequentially located in a cavity of the housing; the fuse structure is connected in parallel to the conductive bar, and a displacement channel is provided in the fuse structure, the displacement channel penetrating both ends of the fuse structure in the direction of piston displacement, and a melt cutter assembly is disposed in the displacement channel in a clearance fit manner; the melt of the fuse structure passes through the displacement channel and is located on the displacement path of the melt cutter assembly; the electronic ignition device can release a driving force in response to a trigger signal, driving the piston to disconnect the conductive bar, and then driving the melt cutter assembly to disconnect the melt;

[0041] A pressure relief air flow channel is also provided in the shell, and the pressure relief air flow channel is communicated with the gap between the melt cutter assembly and the displacement channel.

[0042] The excitation fuse with a pressure reducing and exhaust structure of the present invention has a clearance fit between the displacement channel on the fuse structure connected in parallel to the conductive bar and the melt cutter assembly. A pressure relief airflow channel is provided in the shell and outside the cavity where the electronic ignition device, the piston and the fuse structure are located. A pressure relief gap is provided between the end of the fuse structure away from the piston and the end of the shell. The pressure relief airflow channel, the pressure relief gap, and the gap between the displacement channel and the melt cutter assembly are connected in sequence, so that when the melt of the fuse structure is disconnected, the high-pressure gas generated by the arc enters the pressure relief airflow channel for pressure relief, reducing the gas pressure and the impact energy of the high-pressure gas generated by the arc on the shell, thereby preventing the shell from cracking due to impact. Therefore, in order to improve the pressure reduction effect, a pressure relief cavity that does not affect the disconnection of the conductive bar and the melt and an exhaust port provided on the outside of the shell can also be provided in the shell. The gas pressure is further reduced by the pressure relief cavity connected to the pressure relief airflow channel. On this basis, the exhaust port can also discharge the high-pressure gas generated by the arc to the outside of the shell through the pressure relief airflow channel. Therefore, to improve the pressure relief effect, the pressure relief airflow channel should be as long as possible, and the number and volume of the pressure relief cavities should be as large as possible. The exhaust port should be located at the end closest to the electronic ignition device, away from the fuse structure. This prevents the arc from flying out of the housing through the exhaust port when the exhaust port is close to the fuse structure. The pressure relief airflow channel and pressure relief cavity are designed to ensure that they do not interfere with the disconnection of the conductive bar and the fuse, ensuring the required strength of the housing, while also not increasing the housing volume and preventing the arc from flying out of the housing.

[0043] The pressure relief airflow channel can be a pressure relief chamber formed in the middle of the housing wall thickness, or alternatively, a pressure relief chamber formed through a special structure. This pressure relief chamber can be connected via a pressure relief gap at the end of the displacement channel away from the piston. This arrangement simplifies the structure, makes the dimensions more compact, and reduces the risk of high-pressure gas leakage, making it safer and more reliable. Furthermore, by locating the pressure relief channel outside the piston path, the pressure relief path is longer, improving arc extinguishing performance and reducing arcing during the melt-breaking process.

[0044] Figures 2 to 4 It is a schematic diagram of the principle structure of the excitation fuse with a pressure reducing and exhausting structure of the present invention, including an electronic ignition device 201, a first shell 202, a piston 203, a second shell 204, a conductive bar 205, a third shell 206, a cutter pushing device 207, a melt 208, a protective cover 209, a melt lower cutter 210, a melt protection shell 211, an arc extinguishing medium 212, a melt upper cutter 213, and a melt protection shell cover 214.

[0045] The electronic ignition device 201 is a gas generating device that can be activated according to a trigger signal (current signal or voltage signal) to release high-pressure gas as a driving force.

[0046] The piston 203 is made of an insulating material. The upper melt cutter 213 and the lower melt cutter 210 are also made of an insulating material. To reduce production costs, the first, second, and third shells, as well as the protective cover, are all integrally formed using injection molding. The melt 208 is provided with a narrow neck for fusing and a weak point that serves as a pre-break to reduce mechanical strength. The melt 208 can be mechanically severed at the pre-break.

[0047] The first shell 202 , the second shell 204 , the third shell 206 , and the protective cover 209 are connected in sequence to form a shell structure.

[0048] An electronic ignition device 201 is disposed in the first housing 202 . The electronic ignition device 201 seals the cavity of the first housing 202 in which it is located, thereby preventing high-pressure gas released by the electronic ignition device 201 from leaking out of the first housing 202 .

[0049] A piston 203 is disposed within the second housing 204. A sealing ring is provided at the contact surface between the piston 203 and the second housing 204, forming a sealed cavity between the piston 203 and the electronic ignition device 201. Limiting bumps are provided on opposite sides of the end surface of the piston 203 facing the first housing 202. These limiting bumps are positioned between the contacting end surfaces of the second housing 204 and the first housing 202, forming a limiting structure that defines the initial position of the piston 203. When the piston needs to move, the connection between the piston 203 and the limiting bumps is disconnected, and after overcoming the limiting structure, the piston 203 moves.

[0050] The conductive bar 205 is arranged between the second shell 204 and the third shell 206. In this embodiment, two conductive bars 205 are arranged at an insulating interval. One end of the two conductive bars located outside the shell is connected as a whole to form a common connection end, and the other end is an independent connection end. The two conductive bars can be connected to different circuits respectively. Conductive bar impact ends are respectively provided at the positions of the pistons 203 corresponding to the two conductive bars 205, and a melt impact end is provided at the position of the piston 203 between the two conductive bar impact ends. The melt impact end protrudes from the two conductive bar impact ends. The third shell 206 is provided with a displacement space for the conductive bar 205 after disconnection, and a through hole for the melt impact end of the piston 203 to pass through. The through hole passes through the third shell 206.

[0051] A weak point is defined on conductive bar 205, where it corresponds to the impact end of piston 203, to reduce mechanical strength. This creates a pre-break in conductive bar 205. When the piston's impact end strikes the bar, the bar breaks at the pre-break. The weak point is a groove extending across the width of conductive bar 205, such as a U- or V-shaped groove, to facilitate disconnection.

[0052] Slide grooves are provided on the inner walls of the piston 203 that are in contact with the second and third housings. The piston 203 moves along the slide grooves, ensuring that the piston 203 will not rotate but will only move linearly when it is impacted again.

[0053] A melt protection shell 211 and a melt protection shell cover 214 are disposed in the cavity between the third housing 206 and the protective cover 209. The melt protection shell cover 214 covers the melt protection shell 211, sealing the melt protection shell 211 and forming a sealed cavity within the melt protection shell 211. The melt protection shell 211 is located on one side of the protective cover 209, and the melt protection shell cover 214 is positioned near the conductive bar 205. Displacement channels are defined through the melt protection shell 211 and the melt protection shell cover 214, extending through the melt protection shell 211 and the melt protection shell cover 214. The displacement direction of the displacement channel is the same as that of the piston. The sealed cavity between the melt protection shell 211 and the melt protection shell cover 214 on both sides of the displacement channel is filled with an arc-extinguishing medium 212.

[0054] The protective cover 209 has a box-like structure, with a cavity remaining between the protective cover 209 and the melt protection shell 211. A cavity also remains between the third shell 206 and the melt protection shell cover plate 214. The cavity between the protective cover 209 and the melt protection shell 211 and the cavity between the third shell 206 and the melt protection shell cover plate 214 are connected via a displacement channel. A rubber pad or Myler sheet is installed at the bottom of the protective cover 209, facing the displacement channel, to cushion impacts.

[0055] Melt 208 passes between the melt protection shell 211 and the melt protection shell cover 214, through the arc-extinguishing medium 212, and through the displacement channel. Both ends of melt 208 pass through the third shell 206 to connect electrically to the conductive bar 205, placing melt 208 in parallel with the conductive bar 205. The resistance of the melt is much greater than the resistance of the conductive bar. The melt is provided with a narrow neck and a weak disconnection point that reduces mechanical strength. The narrow neck is a pre-break for thermal melting, and the weak disconnection point is a pre-break designed to facilitate mechanical disconnection of the melt. The weak disconnection point can be a notch on either side of the melt or a groove on the surface of the melt that runs through the width of the melt. The narrow neck and pre-break on the melt are located in the arc-extinguishing medium. Each conductive bar 205 has a melt 208 connected in parallel. The two melts 208 are insulated and separated by a gap between the arc-extinguishing medium and the displacement channel. Melt 208, melt protection shell 211, arc-extinguishing medium 212, and melt protection shell cover 214 form a fuse structure, which is equivalent to a fuse structure connected in parallel to conductive bar 205, disposed between the third housing and the protective cover. As needed, multiple arc-extinguishing chambers filled with arc-extinguishing medium can be formed within melt protection shell 211 and melt protection shell cover 214. The two melts 208 do not need to be disposed in the same arc-extinguishing chamber, but both melts 208 must pass through the displacement channel.

[0056] An upper melt cutter 213 and a lower melt cutter 210 are disposed in the displacement channel. The melt 208 in the displacement channel is clamped between the upper melt cutter 213 and the lower melt cutter 210. The upper melt cutter 213 and the lower melt cutter 210 are clearance-fitted with the displacement channel. The upper melt cutter 213 and the lower melt cutter 210 form a melt cutter assembly.

[0057] Position-limiting bumps are positioned on opposite sides of the end of the lower melt cutter 210 adjacent to the upper melt cutter 213. These bumps engage grooves on either side of the displacement channel, limiting the position of the lower melt cutter 210 while also supporting the upper melt cutter 213. The end of the upper melt cutter 213 facing the conductive bar 205 protrudes from the melt protection shell cover 214 and is located in the cavity between the melt protection shell cover 214 and the third shell 206. A cutter pusher 207 is located in the cavity between the melt protection shell cover 214 and the third shell 206. The cutter pusher 207 is positioned between the end of the upper melt cutter 213 and the third shell 206 and is supported by the end of the upper melt cutter 213. In the initial position, there is space for displacement between the cutter pusher 207 and the melt protection shell cover 214. The cutter pushing device 207 corresponds to a through hole on the third housing 206 for the melt impact end 203b of the piston 203 to pass through.

[0058] Pressure relief airflow channels 215 that are interconnected and pass through both ends of the second and third shells can be provided on the third shell 206 and the second shell 204, respectively, outside the chamber where the electronic ignition device 201 is located, the chamber where the piston 203 is located, and the chamber where the cutter pusher 207 is located. The pressure relief airflow channels 215 are connected to the cavity between the third shell 206 and the protective cover 209. At least one pressure relief groove 202a is provided on the end surface of the first shell 202 outside the chamber where the electronic ignition device 201 is located, facing the second shell 204, to form a pressure relief cavity. The pressure relief groove 202a is connected to the pressure relief airflow channel 215. When multiple pressure relief grooves 202a are provided, the pressure relief grooves 202a are connected to each other. The connection is achieved by providing a groove on the end surface of the first shell 202 that passes through all the pressure relief grooves. A gap is left between the groove and the end surface of the second shell 204 to form a connecting channel.

[0059] To further relieve pressure, an exhaust port 216 is provided on the outer sidewalls of the first and second shells 202 and 204, between the contact surfaces. A thin film structure is provided at the exhaust port 216, serving as a pressure relief valve. A groove is provided at the contact surface between the second and first shells, forming a vent. One end of the vent is connected to the exhaust port 216, and the other end is connected to the pressure relief airflow channel 215. If the high-temperature, high-pressure gas, after decompression, is still sufficiently high to potentially cause the shell to crack, the pressurized gas can break through the thin film structure of the pressure relief valve and be discharged directly to the outside of the shell, further relieving pressure and cooling the gas.

[0060] Working principle:

[0061] During normal current flow, current flows through the conductive bar 205 , and the resistance of the fuse 208 is much greater than the resistance of the conductive bar 205 , so almost no current flows through the fuse 208 .

[0062] When an overload, short circuit or abnormal situation occurs, the electronic ignition device 201 operates according to the trigger signal, releasing high-pressure gas as a driving force to drive the piston 203 to move. The conductive bar impact end of the piston 203 first disconnects the conductive bar 205, and then the current flows through the melt 208. Then the piston 203 continues to move. The melt impact end of the piston 203 drives the cutter pushing device 207 to move. The cutter pushing device 207 drives the upper melt cutter 213 and the lower melt cutter 210 to overcome the limit of the limit protrusion and move, pulling off the melt 208. The fracture position of the broken melt 208 is located in the arc extinguishing medium.

[0063] Arc extinguishing principle:

[0064] When the busbar is disconnected, most of the current is transferred to the fuse. When the busbar is completely disconnected, the current flowing through it is very small, so the arc generated after the busbar is disconnected is very small. When the current is fully transferred to the fuse and flows through it, it melts, or it mechanically breaks at the same time as the fuse melts. Because the narrow neck of the fuse and the pre-break (the weak point of the mechanical break) are both located within the arc-extinguishing medium, the arc-extinguishing medium participates in extinguishing the arc.

[0065] Pressure relief air flow path, see Figure 4 , the direction indicated by the arrow is the direction of gas flow:

[0066] When the melt is disconnected in the arc-extinguishing chamber filled with an arc-extinguishing medium, the arc generated will produce high-temperature, high-pressure gas. After the melt is pulled apart, a through hole is generated at the displacement channel through which the melt passes. The high-temperature, high-pressure gas enters the gap between the melt cutter assembly and the displacement channel through the through hole. Because the cutter pusher presses against the fuse structure when the melt is pulled apart and is compressed by the high-pressure gas released by the electronic ignition device, the high-temperature, high-pressure gas generated by the arc will flow in the direction of low gas pressure. That is, the high-temperature, high-pressure gas generated by the arc will enter the cavity between the third shell and the protective cover through the gap between the melt cutter assembly and the displacement channel, and then enter the pressure relief gas flow channel and the pressure relief groove to reduce pressure and cool down. Because the volume of the pressure relief groove and the pressure relief gas flow channel is dozens to hundreds of times larger than the volume of the gap between the melt cutter assembly and the displacement channel, the pressure of the high-temperature, high-pressure gas is quickly reduced to a level that the plastic shell can withstand, and the gas temperature is also quickly cooled to a safe range. In extreme cases, if the gas pressure after decompression is still too high and may damage the shell, the gas with relatively high pressure after cooling can break through the pressure relief valve, connecting the exhaust port to the outside world, and the gas is discharged to the outside of the shell through the exhaust port, further realizing the function of decompression and exhaust.

[0067] Advantages of this embodiment:

[0068] When the excitation fuse is disconnected, the high-temperature, high-pressure gas generated by the internal arc can be depressurized and cooled through the pressure relief airflow channel and the pressure relief groove, thereby achieving reasonable decompression and cooling of the high-temperature, high-pressure gas and discharging it to the outside when necessary, ensuring that the overall structure of the excitation fuse is not damaged.

[0069] The use of an excitation fuse solution with a pressure-reducing and exhaust structure reduces or even eliminates the risk of shell cracking. The fuse design does not require additional wall thickness to ensure shell strength, nor does it require the use of higher-performance materials. This reduces the design difficulty of the shell structure and also reduces manufacturing costs.

[0070] This avoids arc leakage caused by pressure damage to the shell, as well as the degradation of the internal insulation performance of the excitation fuse and the reduction of the creepage distance, thereby reducing the difficulty of designing the shell's airtightness;

[0071] Due to the addition of pressure reducing and exhaust structures, the requirements for structural strength and sealing are reduced, so that after the product has been used for a long time and aged, the breaking performance and safety reliability of the fuse are significantly improved.

[0072] The excitation fuse with a pressure reducing and exhausting structure can prevent the high-temperature arc from spraying out of the shell and damaging the surrounding devices, thereby improving the protection level.

[0073] The technical solution is now described in detail with reference to preferred embodiments. The directional words in the specification are limited to the directions shown in the drawings and do not constitute a limitation on the technical solution of the present invention.

[0074] Figures 5 to 8 It is a specific structural form of an excitation fuse with a pressure reducing and exhausting structure, including an electronic ignition device 301, a first shell 302, a piston 303, a sealing ring 304, a second shell 305, a conductive bar 306, a cutter pushing device 307, an upper melt cutter 308, an arc extinguishing buffer 309, an arc extinguishing medium 310, a lower melt cutter 311, a protective cover 312, a melt 313, a melt protection shell 314, a third shell 315, and a melt protection shell cover 316.

[0075] The first shell 302, the second shell 305, the third shell 315 and the protective cover 312 are connected in sequence to form a sealed shell structure, and the bolts 318 are passed through the bolt mounting holes of the first shell 302, the second shell 305, the third shell 315 and the protective cover 312 and then locked and fixed.

[0076] The electronic ignition device 301 is installed in the first shell 302, enclosing the cavity of the first shell 302 in which it is located. The piston 303 is arranged in the second shell 305, and a circle of grooves is provided on the outer peripheral surface where the piston 303 contacts the inner wall of the cavity of the second shell 305. A sealing ring 304 is provided in the groove to seal the contact surface between the piston 303 and the second shell 305. A groove is provided on the end surface of the piston 303 corresponding to the end where the driving force of the electronic ignition device 301 is released. A slide groove for linear displacement of the piston 203 is provided in the second shell and the third shell, and ridges provided in the slide groove are provided on both sides of the piston 303 corresponding to the slide groove. The piston 303 is the same as in Example 1, and has an impact end for disconnecting the conductive bar 306 and an impact end for disconnecting the melt.

[0077] The conductive bar 306 is located between the second housing 305 and the third housing 315 , and the conductive bar structure is the same as that in the first embodiment.

[0078] The fuse protection shell cover 316 , the fuse protection shell 314 , the arc extinguishing medium 310 , and the fuse 313 form a fuse structure.

[0079] A melt protection shell cover plate 316 and a melt protection shell 314 are disposed between the third housing 315 and the protective cover 312. An arc-extinguishing cushion 309 is disposed between the melt protection shell 314 and the protective cover 312. Displacement channels on the melt protection shell cover plate 316 and the melt protection shell 314 are positioned directly opposite the arc-extinguishing cushion 309. After the melt 313 passes through the arc-extinguishing medium and the displacement channels, its ends are electrically connected to the conductive bar via bolts. The melt protection shell cover plate 316 has a concave structure, with the cutter pusher 307 located in a groove in the melt protection shell cover plate 316. The upper and lower melt cutters 308 and 311 are located in the displacement channels of the fuse structure and clamp the melt 313. The upper and lower melt cutters 308 and 311 are clearance-fitted with the displacement channels. The end of the upper cutter 308 of the melt protrudes from the bottom of the groove in the melt protection shell cover 316, supporting the cutter pusher 307 and placing it against the third shell 315. Through-holes are provided in the third shell 315 at locations corresponding to the piston's conductive bar impact end and the melt impact end. A nesting groove 307a is provided in the cutter pusher 307 at the location corresponding to the pre-breakage of the conductive bar 306. When the conductive bar 306 is broken by the conductive bar impact end of the piston 303, the broken portion of the conductive bar 306 is driven by the conductive bar impact end of the piston 303 and placed in the nesting groove 307a, providing support for the broken portion of the conductive bar.

[0080] On the outer peripheral side of the melt protection shell 314, the third shell 315 and the second shell 305 outside the chamber where the piston 303 is located are respectively provided with pressure relief airflow channels 317 that are interconnected and pass through the second shell and the third shell. On the docking surface of the second shell 305 and the first shell 302, a plurality of pressure relief grooves (302a, 305a) that are interconnected are respectively provided to form a pressure relief cavity. The pressure relief grooves (302a, 305a) are connected to the pressure relief airflow channel 317, and the pressure relief airflow channel 317 is connected to the cavity between the protective cover 312 and the third shell. A plurality of pressure relief grooves are also provided on the end surface of the third shell 315 facing the protective cover to form a pressure relief cavity. The pressure relief grooves on the third shell are connected to the cavity between the third shell and the protective cover, and are connected to the pressure relief airflow channel. The gap between the bolt 318 and the bolt mounting hole is connected to the pressure relief groove and.

[0081] An exhaust port 319 is located outside the interface between the first and second shells. A pressure relief valve, a thin film structure, is fixed to the exhaust port 319 and seals the exhaust port. A vent groove is formed at the interface between the first and second shells. When the chessboard cover is docked with the second shell, the vent groove forms an exhaust hole. One end of the exhaust hole communicates with the exhaust port and the other end communicates with the pressure relief airflow channel 317. When gas pressure reaches a certain value, it breaks through the thin film structure at the pressure relief valve, opening the exhaust port and allowing gas to be discharged to the exterior of the shells through the vent, reducing pressure and cooling the temperature.

[0082] Its working principle and arc extinguishing principle are the same as Figures 2 to 4 Working principle.

[0083] Its pressure relief air flow path:

[0084] During the melt separation and arc extinguishing process, the high-temperature, high-pressure gas generated by the arc in the arc extinguishing chamber flows through the gap between the displacement channel and the upper and lower melt cutters 311, into the gap between the protective cover 312 and the third housing. The high-temperature, high-pressure gas then enters the pressure relief groove of the third housing for pressure relief and cooling. Simultaneously, the high-temperature, high-pressure gas flows sequentially through the third housing 315 and the pressure relief gas flow channel 317 in the second housing 305, entering the interconnected pressure relief grooves of the first and second housings 302, 305 for pressure relief and cooling. The combined volume of the pressure relief grooves and the pressure relief gas flow channel of the first, second, and third housings is tens to hundreds of times greater than the volume of the gap between the displacement channel and the upper and lower melt cutters. Therefore, the pressure of the high-temperature, high-pressure gas generated by the arc is rapidly reduced to a level that the plastic housing can withstand, and the gas temperature is also rapidly cooled to a safe range. When the gas pressure rapidly decreases to a lower value, insufficient to damage the membrane at the pressure relief valve, the membrane at the pressure relief valve remains intact.

[0085] In extreme cases, if the gas pressure after decompression is still too high and may damage the shell, the pressure of the cooled high-pressure gas can break through the membrane at the pressure relief valve, so that the pressure relief air flow channel inside the shell is connected to the outside of the shell, and the pressure is directly relieved to the outside of the shell. Through the setting of the pressure relief valve, the pressure relief valve becomes the weak point of the shell structure. When the gas pressure is high, the weak point of the pressure relief valve will be broken first, avoiding the possibility of cracking the shell and causing impact on external equipment.

[0086] At the same time, the cooled high-pressure gas can also be discharged to the outside of the shell through the bolt mounting holes at the first shell and the mounting gaps between the bolts, thereby achieving the function of reducing pressure and exhausting.

[0087] Secondly, a diaphragm can be added to the exhaust port of the first shell 302 as a pressure relief valve, which can ensure airtightness and also ensure that the diaphragm automatically opens to relieve pressure under a certain pressure.

[0088] Figures 9 to 11 It is another specific structural form of an excitation fuse with a pressure reducing and exhausting structure, including an electronic ignition device 401, a pressure cover 402, a first shell 403, a second shell 404, a sealing ring 405, a piston 406, a conductive bar 407, a third shell 408, a melt protection shell 409, a protective cover 410, an arc extinguishing buffer pad 411, an arc extinguishing medium 412, a melt lower cutter 413, a melt 414, a melt upper cutter 415, a cutter pushing device 416, and a melt protection shell cover 417.

[0089] Figures 9 to 11 The structure is basically the same as Figures 5 to 8 The difference is that the first shell is replaced by the combination of the pressure cover 402 and the first shell 403.

[0090] A receiving groove is defined on the end surface of the second housing 404 facing the gland 402, and the cavity containing the piston 406 communicates with the receiving groove. One end of the gland 402 is positioned in the receiving groove of the second housing 404 and is secured to the second housing 404 by the first housing 403. The electronic ignition device 401 is positioned on the gland 402 and secured to the gland 402 by the first housing 403. The chamber containing the driving force release end of the electronic ignition device 401 communicates with the chamber containing the end surface of the piston 406 facing the electronic ignition device 401.

[0091] A pressure relief air flow channel 418 communicating with each other is provided on the second shell 404 and the third shell 408 . The pressure relief air flow channel 418 is communicated with the cavity between the protective cover 410 and the third shell 408 .

[0092] An annular pressure relief groove 419 connected to the pressure relief airflow channel 418 is provided on the end surface of the second shell 404 outside the chamber where the electronic ignition device 401 is located, facing the first shell 403. A tubular pressure relief groove 420 is provided on the end surface of the second shell outside the cavity where the electronic ignition device and the piston are located, where it contacts the pressure cover 402. The tubular pressure relief groove 420 is connected to the annular pressure relief groove 419 through the assembly gap between the second shell 404 and the side wall of the pressure cover 402. A tubular pressure relief groove 421 is provided on the pressure cover 402 outside the cavity where the electronic ignition device 401 is located. The tubular pressure relief groove 421 is connected to the annular pressure relief groove 419 through the assembly gap between the pressure cover 402 and the first shell 403. A tubular pressure relief groove is also provided on the end surface of the third shell facing the protective cover. The pressure relief groove on the third shell is connected to the cavity between the third shell and the protective cover, and is connected to the pressure relief airflow channel.

[0093] A plurality of pressure relief vents 422 are provided at intervals on the end surface of the second housing 404 outside the annular pressure relief groove 419. The pressure relief vents 422 are connected to the annular pressure relief groove 419. A pressure relief film structure is provided at the pressure relief vents 422 to seal the pressure relief vents.

[0094] Its pressure relief air flow path:

[0095] During the melt breaking and arc extinguishing process, the high-temperature, high-pressure gas generated by the arc passes through the gap between the upper melt cutter, the lower melt cutter and the displacement channel into the gap between the protective cover and the third shell, and then enters the annular pressure relief groove 419 and the tubular pressure relief groove through the pressure relief air flow channel 418 for pressure relief and cooling.

[0096] In extreme cases, when the gas pressure inside the shell after pressure relief and cooling is still large enough to cause damage to the shell, the gas pressure breaks through the pressure relief film at the pressure relief outlet 422 and directly releases pressure to the outside of the shell.

[0097] In summary, the present invention aims to:

[0098] A pressure relief airflow channel is provided in the shell of an excitation fuse in which a fuse structure is connected in parallel to the conductive bar and the melt of the fuse structure needs to be disconnected by a melt cutter assembly, so as to reduce the pressure and temperature of the high-temperature and high-pressure gas generated by the arc in the arc extinguishing chamber after the melt is disconnected, so that the pressure reaches a value below the safe pressure value that the shell can withstand. Therefore, inside the shell, it is necessary to increase the volume of the pressure relief space as much as possible without affecting the normal operation of the excitation fuse. It can be seen from the above embodiments that the volume of the pressure relief space is increased by lengthening the length of the pressure relief airflow channel. At the same time, under the principle of meeting the strength of the shell, one or more pressure relief cavities connected to the pressure relief airflow channel are provided inside the shell to further increase the volume of the pressure relief space and reduce pressure and cool down.

[0099] As a response measure in extreme situations, a film-type pressure relief valve is set on the outside of the shell, and the pressure relief valve is connected to the pressure relief air flow channel. When the gas pressure passing through the above-mentioned pressure relief air flow channel and the incisor cavity is not enough to reduce the gas pressure to a safe pressure value, the gas pressure can break through the film at the pressure relief valve and discharge the high-pressure gas directly to the outside of the shell, thereby achieving the purpose of quickly reducing the gas pressure and cooling the gas, thereby protecting the shell and protecting the equipment and circuits around the excitation fuse.

Claims

1. An excitation fuse with a pressure reducing and exhausting structure, characterized in that: The invention comprises: a housing, and an electronic ignition device, a piston, a conductive bar, and a fuse structure sequentially located in a cavity of the housing; the fuse structure is connected in parallel to the conductive bar, a displacement channel is provided on the fuse structure, the displacement channel passes through both ends of the fuse structure in the displacement direction of the piston, and a melt cutter assembly is provided in the displacement channel in a clearance fit manner; the melt of the fuse structure passes through the displacement channel and is located on the displacement path of the melt cutter assembly; the electronic ignition device can release a driving force according to a trigger signal, driving the piston to disconnect the conductive bar, and then driving the melt cutter assembly to disconnect the melt; A pressure relief air flow channel is also provided in the housing, and the pressure relief air flow channel is communicated with the gap between the melt cutter assembly and the displacement channel.

2. The excitation fuse according to claim 1, characterized in that The pressure relief air flow channel is provided between the two ends of the housing in the displacement direction of the piston and the fuse disconnect assembly, and is located in the housing on the outer peripheral side of the cavity where the electronic ignition device, the piston and the fuse structure are located; A pressure relief gap is provided between one end of the fuse structure facing the end position of the melt cutter assembly and the shell, and the pressure relief gap is respectively communicated with one end of the pressure relief airflow channel facing the end position of the melt cutting assembly and the gap between the displacement channel and the melt cutter assembly.

3. The excitation fuse according to claim 2, characterized in that At least one pressure relief cavity is further provided in the housing between the two ends of the housing in the displacement direction of the piston and the melt disconnect assembly and located on the outer peripheral side of the cavity where the electronic ignition device, the piston and the fuse structure are located. The pressure relief cavity is communicated with the pressure relief air flow channel.

4. The excitation fuse according to claim 2, characterized in that An exhaust port is provided on the outer side wall of the shell, and the exhaust port is communicated with one end of the pressure relief air flow channel away from the end position of the melt cutter assembly.

5. The excitation fuse according to claim 4, characterized in that The other end of the pressure relief air flow channel where the melt cutter assembly terminates is located in the housing outside the cavity where the electronic ignition device is located.

6. The excitation fuse according to claim 4, characterized in that A pressure relief valve is provided at the exhaust port.

7. The excitation fuse according to claim 6, characterized in that The pressure relief valve is a thin film structure and closes the exhaust port.

8. The excitation fuse according to claim 4, characterized in that The shell includes a first shell, a second shell, a third shell and a protective cover which are spliced ​​together in sequence; the electronic ignition device is arranged in the first shell, the piston is arranged in the second shell, the fuse structure is arranged in the third shell, and the pressure relief gap is arranged between the fuse structure and the protective cover; the pressure relief airflow channel is arranged in the third shell, or in the third shell and the second shell, or in the third shell, the second shell and the first shell; at least one pressure relief cavity is arranged in one of the first shell, the second shell and the third shell on one side of the pressure relief airflow channel, or in any two or more of them.

9. The excitation fuse according to claim 8, characterized in that The pressure relief cavity is located on one or two end surfaces of the first shell, the second shell and the third shell, and the pressure relief cavity is formed by a pressure relief groove provided on the end surface.

10. The excitation fuse according to claim 9, characterized in that One end of the pressure relief air flow channel away from the protective cover and the exhaust port are respectively located on the end surface of the second shell facing the first shell, and the exhaust port is communicated with the pressure relief air flow channel.

11. The excitation fuse according to claim 10, characterized in that: An accommodating groove is provided on the end face of the second shell facing the first shell, the first shell is provided in the accommodating groove, and a pressure cover is provided on the end face of the first shell located outside the shell, the pressure cover is connected to the second shell and fixes the first shell; the pressure relief air flow channel extends to the end face of the second shell in contact with the pressure cover, the pressure relief cavity is provided on the end face of the first shell facing the pressure cover, and a pressure relief gap is provided between the first shell and the pressure cover from the pressure relief cavity to the outer side face of the shell, and the pressure relief gap is respectively communicated with the pressure relief cavity and the pressure relief air flow channel provided on the end face of the first shell facing the pressure cover.

12. The excitation fuse according to claim 11, characterized in that The second shell located on the outside of the first shell is provided with a circle of annular pressure relief grooves at the end face facing the pressure cover, and the annular pressure relief grooves are connected with the pressure relief air flow channel; the pressure relief cavity on the end face of the second shell facing the pressure cover, and the pressure relief cavity on the end face of the first shell facing the pressure cover, the pressure cover outside the first shell, the second shell and the pressure cover, and the second shell and the first shell are clearance fit.

13. The excitation fuse according to any one of claims 1 to 12, characterized in that: The shell is provided with bolt mounting holes that pass through both ends of the piston in the displacement direction, and the bolts are passed through the bolt mounting holes in a clearance fit manner to fix the shell; the pressure relief air flow channel or the pressure relief cavity is connected to the gap between the bolt mounting hole and the bolt.

14. The excitation fuse according to any one of claims 8 to 12, characterized in that: A cutter pushing device is provided between the fuse structure and the third shell. The melt cutter assembly protrudes from the fuse structure toward one end of the conductive bar and supports the cutter pushing device. When the piston is displaced, the cutter pushing device can be driven to move, and the cutter pushing device drives the melt cutter assembly to move.

15. The excitation fuse according to any one of claims 8 to 12, characterized in that: A buffer pad is provided in the pressure relief gap between the fuse structure and the protective cover, and the displacement channel is provided corresponding to the buffer pad.

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