A hybrid fuse

Abstract

A hybrid fuse includes a first fuse, a breaking assembly and a second fuse arranged in a housing, the first fuse includes a first conductor, a first fuse body and a conducting plate arranged in series; the housing includes an upper housing, a middle housing and a lower housing, the middle housing is provided with a composite arc channel plate, the upper housing is provided with a composite support plate, the conducting plate and the first conductor are arranged on the composite arc channel plate, the composite arc channel plate is provided with a guide groove, and the lower housing is provided with an arc extinguishing chamber; the composite arc channel plate is provided with an isolation cover arranged outside the breaking assembly, the isolation cover, the conducting plate, the composite arc channel plate, the guide groove and the arc extinguishing chamber located at the bottom of the isolation cover form a cutting closed space for the breaking assembly to break down, the part of the housing inside the arc extinguishing chamber and outside the isolation cover forms an inner cavity where the first fuse is arranged, the second fuse is arranged in the inner cavity where the first fuse is arranged, and the inner cavity where the first fuse is arranged is filled with arc extinguishing medium. The present application can reduce the volume, prevent explosion, simplify the process of components and facilitate assembly and production.

Description

Technical Field

[0001] This invention belongs to the field of circuit protection, and more specifically relates to a hybrid fuse. Background Technology

[0002] Traditional fuses rely on Joule heating to melt the internal fusible element and use quartz sand filler to extinguish the arc, and are widely used in electronic power systems. For semiconductor devices, protection devices with millisecond-level rapid disconnection capabilities are needed for effective protection. For wind, solar, and energy storage systems with chemical batteries, there are situations where power generation is extremely low on cloudy days but short-circuit faults occur simultaneously, requiring rapid circuit disconnection for high fault currents. This necessitates protection devices with extremely high and low overload protection capabilities to minimize the damage caused by faults. For traditional high-voltage, low-rated-current fuses, arc-extinguishing sand alone can extinguish the arc within milliseconds. However, higher-power circuits require fuses with larger rated values. With higher rated currents, the required amount of fusible element increases to handle the normally large operating current, making it difficult to disconnect within milliseconds under high voltage and high fault current conditions. Existing high-rated-current traditional fuses also cannot provide protection against extremely low fault currents. To address this, a main current path is formed by connecting a fuse capable of handling a large current and a cutting device in series. The cutting device is driven by explosives. This path is simultaneously connected in parallel to a high-resistance branch formed by an external high-voltage arc-extinguishing fuse with a smaller rated value. This, along with a current monitoring module and a module that triggers the explosives with a signal, forms a new hybrid fuse, which has been applied to the power system. This type of product achieves the above protection objectives in terms of function, but it has problems such as loose structure (many parts), large size, and high cost.

[0003] Hybrid fuses, especially those combining explosive-driven switches and fuses, are categorized into externally triggered and self-triggered types. Both incorporate an explosive-driven device to cut off the conductor path. Currently, most of these products are custom-designed individual units that use explosive gas generation to break the copper busbar conductor. Some have the gas generation unit located outside the hybrid fuse (because it's easier to damage the casing during explosion and also facilitates replacement), while others, although located inside the casing, still have the gas generation unit and its arc-extinguishing chamber unit as separately detachable units without effective protection. Furthermore, the gas generation chamber component of the breaking assembly experiences high internal gas pressure upon triggering, making the casing prone to explosion and causing breaking failure. With the gas generation unit located externally, the exploding casing can easily affect external components of the fuse, posing a danger to the external environment, and increasing the product's size. These risks are particularly pronounced in miniaturized products. Currently, these products are increasingly being used in wind, solar, and energy storage systems. The original design of these systems used ordinary fuses, and the available space for their installation could not be expanded to accommodate the larger fuses. Therefore, to balance global business competition, a hybrid fuse that is small in size, reliable in structure, and has a good cost performance is needed. Summary of the Invention

[0004] The purpose of this invention is to provide a hybrid fuse that is smaller in size, has a reliable structure, is safe and explosion-proof, has simplified components, is simple to manufacture and easy to assemble.

[0005] To achieve the above objectives, the solution of the present invention is: A hybrid fuse includes a first fuse, a tripping assembly, and a second fuse housed within a housing. The first fuse comprises a first conductor, a first fusible element, and a conductive plate. The tripping assembly is located above the conductive plate. The first conductor is connected in series with the conductive plate via the first fusible element. The second fuse is connected in parallel with the branch containing the first fuse. When the circuit is normally conducting, most of the current flows through the first fuse, while a small portion flows through the branch containing the second fuse. When a fault current occurs, the first fusible element melts and arcs, simultaneously generating an electrical signal to trigger the tripping assembly to cut off the conductive plate. The current is then transferred to the branch containing the second fuse, which then melts and breaks the fault current. The shell has a cavity, and the shell includes an upper shell, a middle shell and a lower shell. The middle shell has a composite arc plate, the upper shell has a composite support plate, a conductive plate and a first conductor are mounted on the composite arc plate, and the breaking assembly includes a gas generator and a piston. The composite arc plate is provided with a guide groove that can guide the piston to move downward. The lower shell is provided with an arc extinguishing chamber corresponding to the guide groove. When the piston has not yet moved downward, it is limited above the conductive plate. An isolation cover is installed above the composite arc plate, which can be placed outside the breaking assembly. The interior of the isolation cover, together with the conductive plate at its bottom, the composite arc plate, the guide groove, and the arc-extinguishing chamber of the lower shell, constitutes the cutting closed space for the breaking assembly to perform downward cutting. The part of the internal cavity of the shell located outside the isolation cover and the cutting closed space forms the inner cavity where the first fuse is located. The second fuse is located in the inner cavity where the first fuse is located. The inner cavity where the first fuse is located is filled with arc-extinguishing medium. Furthermore, the composite support plate is located above the composite arc plate. The composite support plate has a first through-hole through which the piston can pass. The isolation shell forms a shell with a bottom opening. A gas-generating chamber is formed inside the isolation shell. The top of the isolation shell has a top groove for accommodating the gas generator. The piston is inserted into the isolation shell and pushed downward by the driving force generated by the gas generator. The piston passes downward through the first through-hole to the conductive plate. The guide groove is located on the side of the composite arc plate corresponding to the breaking assembly. The composite arc plate has a first partition that separates the side with the guide groove from the side located in the inner cavity of the first fuse. The arc-extinguishing chamber is located on the side of the lower shell corresponding to the breaking assembly. The lower shell has a second partition that separates the side with the arc-extinguishing chamber from the side located in the inner cavity of the first fuse. When the middle shell and the lower shell are connected, the first partition and the second partition combine to form a lower baffle wall. The lower baffle wall isolates the cut-off closed space and the inner cavity of the first fuse.

[0006] Furthermore, the first bottom cavity is defined as the side of the inner cavity where the first fuse is located in the lower shell. The second fuse is mounted in the middle shell or in the first bottom cavity. The outer side of the second fuse is filled with an arc-extinguishing medium, which is quartz sand.

[0007] Furthermore, the second fuse includes an insulating shell with end caps at both ends, a fusible element connected between the two end caps along the length of the insulating shell, and the insulating shell is filled with an arc-extinguishing medium; the two ends of the first fuse are defined as a first end electrode and a second end electrode, respectively, and one end cap of the second fuse is connected to the portion of the first end electrode located inside the cavity of the first fuse through a metal conductive sheet, and the other end cap is connected to the portion of the second end electrode located inside the shell cavity through a metal conductive sheet.

[0008] Furthermore, the second fuse is mounted inside the middle shell and located above the composite support plate. The composite support plate has two side through holes for the metal conductive sheet to pass through. After the metal conductive sheet passes through and is installed, the side through holes are sealed with epoxy resin. The first bottom cavity is provided with multiple sets of support pillars, each support pillar is supported between the bottom surface of the composite arc plate and the bottom plate of the lower shell, and there is a gap between the multiple sets of support pillars. The first bottom cavity is filled with arc extinguishing medium.

[0009] Furthermore, both the upper shell and the middle shell are hollow shells. The composite arc plate is located near the top of the middle shell, and the outer wall of the middle shell forms a retaining edge on the outer periphery of the composite arc plate. The composite support plate is located at the bottom of the upper shell. The bottom surface of the composite support plate is provided with a protruding strip that can be embedded in the inner side of the retaining edge for limiting. The composite support plate and the composite arc plate are interlocked when the upper shell and the middle shell are connected and combined. The first conductor and the conductive plate connected to the composite arc plate are located between the two protruding strips and also between the composite support plate and the composite arc plate. The composite support plate is provided with a first through-hole for the piston to pass through and a second through-hole for communicating with the arc-extinguishing medium of the middle shell. The isolation cover is located inside the upper shell. The bottom of the isolation cover is located on the composite support plate and outside the first through-hole. A sealing gasket or sealant is provided between the bottom of the isolation cover and the composite support plate. The composite arc plate is provided with a third through-hole that communicates with the lower shell in the area corresponding to the first conductor, the first fusible element, and the conductive plate in the cavity where the first fuse is located. Furthermore, in the composite arc plate, two sets of positioning pins are protruding in the area outside the third through-hole, corresponding to the positions of the first conductor and the conductive plate, respectively. The first conductor and the conductive plate are respectively provided with positioning through holes corresponding to the positioning pins. When the positioning pins are inserted into the positioning through holes, the first conductor and the conductive plate are positioned on the composite arc plate.

[0010] Furthermore, the composite arc plate has a boss at the position of the punching component, and the isolation cover is located above the boss. At least two first connecting holes are provided around the boss. The composite support plate is located on top of the boss. The composite support plate has a second connecting hole corresponding to each of the first connecting holes. The cover of the isolation cover has a third connecting hole corresponding to the first connecting hole. The isolation cover, the composite support plate, and the composite arc plate are fastened together by passing screws through the third connecting hole, the second connecting hole, and the first connecting hole in sequence.

[0011] Furthermore, the boss has a limiting groove located above the guide groove for the conductive plate to be embedded and limited. The two sides of the boss form notches for the conductive plate to pass through. The conductive plate fits into the notches to form a stop, and the stop seals and stops on the notches.

[0012] Furthermore, the piston includes a piston head and a blade. The bottom of the piston head is provided with at least one blade for cutting the conductive plate. The composite arc plate is provided with guide grooves corresponding to the number of blades. The guide grooves are matched with the shape of each blade. The conductive plate is provided with a pre-cutting part located below the blade. After the blade moves downward past the pre-cutting part, it inserts into the guide groove. The downward-moving blade cuts the pre-cutting part. There is a partition wall between adjacent guide grooves. The part of the conductive plate corresponding to the breaking component is mounted on the partition wall, and the pre-cutting part is located between the partition walls.

[0013] With the above structure, the hybrid fuse of the present invention combines a first fuse and a second fuse, enabling rapid response and reliable disconnection in case of circuit abnormalities. The first conductor and conductive plate are fixed and limited within the space where the composite arc plate and composite support plate are interlocked inside the housing. The lower shell integrates the arc-extinguishing chamber and the chamber of the first fuse and is interlocked with the middle shell, simplifying the number of components and structure and improving production efficiency. Furthermore, heat dissipation is achieved through direct contact with fillers such as quartz sand via a third through-hole, facilitating miniaturization. After the cutting components are independently isolated within the housing cavity of the hybrid fuse, a third... The inner cavity of the first fuse is divided into two parts. The second fuse is located in the same cavity as the first fuse, which reduces the volume and maximizes the filling space of the fuse, thus achieving better cooling and arc extinguishing. At the same time, the second fuse is a complete fuse, which is convenient for installation. It will not damage the hybrid fuse housing in the event of a fault current. The outer exterior of the entire punching assembly, including the isolation cover, is protected by the superposition of quartz sand and the hybrid fuse housing, which makes it less likely to burst and fail when the punching assembly is gas driven. The overall structure is reliable, safe and explosion-proof, which improves product quality and safety. Attached Figure Description

[0014] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a structural exploded view of the present invention; Figure 3 This is a schematic diagram of the structure of the present invention (with the top cover of the upper shell removed). Figure 4 This is a schematic diagram of the structure of the present invention (with part of the upper shell removed). Figure 5 This is a cross-sectional view of the present invention (with the top shell removed); Figure 6 This is a schematic diagram of the structure of the middle shell of the present invention; Figure 7 This is a schematic diagram of the structure of the middle shell of the present invention (showing the bottom); Figure 8 This is a schematic diagram of the upper shell structure of the present invention; Figure 9 This is a schematic diagram of the upper shell structure of the present invention (showing the bottom).

[0015] Label Explanation: Cut off enclosed space A; Cavity B where the first fuse is located; First fuse 1; First terminal electrode 1a; Second terminal electrode 1b; First conductor 11; First positioning through hole 111; First melt 12; Conductive plate 13; Second positioning through hole 131; 132; 133; Second fuse 2; Insulating housing 21; End cap 22; Fusible element 23; Metal conductive sheet 24; Breaking assembly 3; Gas generator 31; Piston 32; Piston head 321; Blade 322; Upper shell 4; Composite support plate 40; Protrusion 41; First through hole 42; Second through hole 43; Top cover 44; Support frame 45; Side through hole 46; Second connecting hole 47; 5. Middle shell; 50. Composite arc plate; 51. Guide groove; 52. First partition plate; 53. First support column; 54; through-hole 541; locating pin 55; boss 56; first connecting hole 561; Limiting groove 562; Notch 563; Partition wall 57; Third through hole 58; Lower shell 6; Arc extinguishing chamber 61; Second partition 62; First bottom cavity 63; Second support column 64; Isolation housing 71; Top recess 711; Third connection hole 712; Sealing gasket 72; Fourth connecting hole 721. Detailed Implementation

[0016] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0017] Combination Figures 1 to 9As shown, this invention discloses a hybrid fuse, comprising a first fuse 1, a tripping assembly 3, and a second fuse 2 housed within a casing. The first fuse 1 includes a first conductor 11, a first fusible element 12, and a conductive plate 13. The first conductor 11 is connected in series with the first fusible element 12 and the conductive plate 13. The second fuse 2 is connected in parallel with the branch containing the first fuse 1. The tripping assembly 3 is located above the conductive plate 13. When the circuit is normally conducting without fault current, most of the current flows through the first fuse 1, while a small portion flows through the branch containing the second fuse 2 (the second fuse has a higher resistance). When a fault current occurs, the first fusible element 12 melts and arcs, simultaneously generating an electrical signal to trigger the tripping assembly 3 to cut the conductive plate 13. The current flowing through the first fuse 1 is transferred to the branch containing the second fuse 2, and the second fuse 2 melts, interrupting the fault current. The first fusible element 12 may have multiple through holes 111 forming a narrow neck, facilitating arc initiation for both high and low overload fault currents. With the above structure, under normal circuit conditions, the current mainly flows through the low-impedance branch where the first fuse 1 is located, thus maintaining low loss during normal operation. When the circuit malfunctions, the first fuse 12 melts and arcs first due to abnormal current, simultaneously generating an electrical signal that triggers the tripping assembly 3 to cut off the conductive plate 13. At this time, the current in the branch where the first fuse 1 is located is forced to transfer to the branch where the second fuse 2 is located. The total current surges after the transfer, exceeding the rated value of the second fuse 2, causing it to melt rapidly and form final protection. In this way, regardless of whether the first fuse 1 melts and arcs under high or low fault current, the fault current in the circuit is ultimately cut off by the high-voltage, low-rated second fuse through the first fuse 12, the tripping assembly 3, and the second fuse 2. This achieves miniaturization of the high-voltage, high-rated-current fuse and enables protection against both high and low fault currents. Its main principle is that when the rated operating current is large under normal conditions, it is mainly borne by the branch where the first fuse is located. When a fault current occurs, it is transferred to the high-voltage, low-rated fuse, that is, the second fuse with a higher resistance value, to limit the current and cut off the fault current of the circuit, so as to achieve fast and safe disconnection.

[0018] In this embodiment, the housing of the hybrid fuse is square, with a cavity formed inside. The housing includes an upper shell 4, a middle shell 5, and a lower shell 6. The upper shell 4 (including a detachable top cover 44), the middle shell 5, and the lower shell 6 can be locked together by multiple bolts and nuts. In this invention, the middle shell 5 has a composite arc plate 50, the upper shell 4 has a composite support plate 40, the conductive plate 13 and the first conductor 11 are mounted on the composite arc plate 50, the breaking assembly 3 includes a gas generator 31 and a piston 32, the composite arc plate 50 is provided with a guide groove 51 to guide the piston 32 to move downward, the lower shell 6 is provided with an arc-extinguishing chamber 61 corresponding to the lower part of the guide groove 51, and the piston 32 is limited above the conductive plate 13 before it moves downward. An isolation cover 71, which can be installed above the composite arc plate 50 and can be placed outside the punching assembly 3, is installed above the composite arc plate 50. The guide groove 51 is located below the isolation cover 71. The interior of the isolation cover 71, together with the conductive plate 13 at its bottom, the composite arc plate 50, the guide groove 51, and the arc-extinguishing chamber 61 of the lower shell 6, constitutes the cutting closed space A for the punching assembly 3 to perform downward cutting. The part of the internal cavity of the shell located outside the isolation cover 71 and the cutting closed space A forms the inner cavity B where the first fuse is located. The second fuse 2 is located in the inner cavity B where the first fuse is located. The inner cavity B where the first fuse is located is filled with an arc-extinguishing medium (not shown in the figure). The arc-extinguishing medium can be a medium with arc-extinguishing and cooling effects, such as quartz sand. Specifically, when the upper shell 4 is connected to the middle shell 5, the composite support plate 40 is located above the composite arc plate 50. The composite support plate 40 has a first through-hole 42 through which the piston 32 can pass, and the first through-hole 42 is contained within the cut-off closed space A. The isolation cover 71 forms a cover with a bottom opening. The interior of the isolation cover 71 forms a gas-generating chamber. The top of the isolation cover 71 has a top groove 711 for accommodating the gas generator 31. The signal connector 4 in the gas generator 31 protrudes from the top of the isolation cover 71. The piston 32 is inserted into the isolation cover and pushed downward by the driving force generated by the gas generator 31. The piston 32 passes downward through the first through-hole to the conductive plate 13. The guide groove 51 is located on the side of the composite arc plate 50 corresponding to the breaking assembly 3. The composite arc plate 50 has a first partition 52 that separates the side with the guide groove 51 from the side located in the inner cavity B where the first fuse is located. The arc-extinguishing chamber 61 is located on one side of the lower shell 6 corresponding to the breaking assembly 3. The lower shell 6 has a second partition 62 that separates the side with the arc-extinguishing chamber 61 from the side located in the cavity B where the first fuse is located. When the middle shell 5 and the lower shell 6 are connected, the first partition 52 and the second partition 62 combine to form a lower baffle wall, which isolates the cut-off enclosed space A and the cavity B where the first fuse is located. The first partition 52 and the second partition 62 can be stacked vertically or form a covering. In this embodiment, the length of the first partition 52 is greater than that of the second partition 62. When the middle shell 5 and the lower shell 6 are stacked vertically, the first partition 52 faces the cavity B where the first fuse is located, and the second partition 62 can be abutted behind the first partition 52, so that the cut-off enclosed space A is isolated in the lower shell 6. The isolation housing 71 independently encloses the gas generator 31 and piston 32 of the breaking assembly 3. The downward stroke space of the piston 32 is also combined with the arc-extinguishing chamber 61 in the lower shell through the composite arc channel plate 50 to form an independent cutting-off closed space A. The cutting-off closed space A is not affected by the arc-extinguishing medium. Since the isolation housing 71 is surrounded by the arc-extinguishing medium (quartz sand, etc.), the fully filled arc-extinguishing medium is restricted by the shell of the hybrid fuse. The isolation housing 71 is fixed by the external quartz sand and other filling materials and the shell, as well as by the absorption of impact force by the quartz sand. When the breaking assembly 3 is working, the interlocking between the quartz sand particles on the outside of the isolation housing 71 breaks under the action of impact force to form a new interlocking process, absorbing the impact energy. After the superimposed protection of quartz sand and the hybrid fuse shell, the isolation housing 71 is not easy to burst and fail, which also improves the reliability and safety of the product, and enhances the product quality and safety.

[0019] The first bottom cavity 63 is defined as the side of the inner cavity B where the first fuse is located in the lower shell 6. The second fuse 2 can be installed in the middle shell 5 or the first bottom cavity 63. The outer side of the second fuse 2 is filled with arc-extinguishing medium. That is, in the inner cavity B where the first fuse is located, two cavities are formed with the composite arc duct plate 50 as the boundary. The cavity where the second fuse 2 is not installed will be filled with arc-extinguishing medium. The arc-extinguishing medium can be quartz sand.

[0020] The second fuse 2 includes an insulating shell 21 with end caps 22 at both ends. The insulating shell 21 can be a fiberglass composite tube or a ceramic tube. A fusible element 23 is provided along the length of the insulating shell 21 and connected between the end caps 22. The fusible element 23 can also be bent into shape. The insulating shell 21 is filled with an arc-extinguishing medium, which can also be quartz sand. The two ends of the first fuse 1 are defined as a first end electrode 1a and a second end electrode 1b, respectively. In this embodiment, the end of the first conductor 11 away from the conductive plate 13 is the first end electrode 1a, and the opposite end of the conductive plate 13 near the shell wall is the second end electrode 1b. One end cap 22 of the second fuse 2 is connected to the portion of the first end electrode 1a located inside the cavity B of the first fuse through a metal conductive sheet 24, and the other end cap 22 is connected to the portion of the second end electrode 1b located inside the shell cavity through a metal conductive sheet 24, so that the second fuse 2 and the branch where the first fuse 1 is located are connected in parallel and located inside the shell of the hybrid fuse. In the second fuse 2, the inner fusible element 23 is surrounded by a composite tube of glass fiber cloth with strong heat resistance and explosion resistance, which improves the heat resistance, heat insulation and explosion resistance. When the hybrid fuse interrupts high fault current, the high arc energy of the fusible element 23 of the second fuse 2 is less likely to damage the casing of the hybrid fuse, especially when the hybrid fuse uses an engineering plastic casing with low heat resistance. The overall structure of the second fuse 2, compared to a structure with only a single fuse element, allows for direct connection of the customized second fuse, which also facilitates the production and installation of the hybrid fuse and improves efficiency.

[0021] Combination Figure 2 and 6 to Figure 9As shown, both the upper shell 4 and the middle shell 5 are hollow shells. The composite arc plate 50 is located near the top of the middle shell 5, and the outer side wall of the middle shell 5 forms a retaining edge 54 on the outer periphery of the composite arc plate 50. The retaining edge 54 has an outlet 541 through which the first conductor 11 and conductive plate 13 can pass, facilitating the electrical connection between the first fuse 1 and external components. The composite support plate 40 is located at the bottom of the upper shell 4. The bottom surface of the composite support plate 40 has a protruding strip 41 that can be embedded in the inner side of the retaining edge 54 for limiting, so that the composite support plate 40 and the composite arc plate 50 can be interlocked when the upper shell 4 and the middle shell 5 are connected and combined. The first conductor 11 and conductive plate 13 connected to the composite arc plate 50 are located between the two protruding strips 41 and also between the composite support plate 40 and the composite arc plate 50. The composite support plate 40 is also provided with a second through-hole 43 that communicates with the arc-extinguishing medium of the middle shell 5. The isolation cover 71 is located inside the upper shell 4, and the bottom of the isolation cover 71 is located on the composite support plate 40 and outside the first through-hole 42. A sealing gasket or sealant is provided between the bottom of the isolation cover 71 and the composite support plate 40. In this embodiment, it is a sealing gasket 72. The sealing gasket 72 can ensure the seal when the isolation cover 71 is connected to the upper shell 4. The mounting surface of the isolation cover 71 can also be coated with sealant such as epoxy resin to achieve complete isolation and prevent the quartz sand in the inner cavity B where the first fuse is located from entering the internal space of the breaking assembly 3.

[0022] The composite arc plate 50 has a third through-hole 58 in the region of the inner cavity B where the first fuse is located, corresponding to the first conductor 11, the first molten element 12 and the conductive plate 13. The third through-hole 58 is connected to the first bottom cavity 63. The three third through-holes 58 can ensure that the arc extinguishing medium can contact the molten element and electrode contained in the first fuse 1 when it is located in the inner cavity B where the first fuse is located, and encapsulate a larger mass of arc extinguishing medium, which is beneficial for heat dissipation.

[0023] In this embodiment, the second fuse 2 is mounted inside the middle shell 5 and located above the composite support plate 40. The upper shell 4 also includes a detachably connected top cover 44. The upper shell 4 also has a support frame 45 for mounting the insulating shell 21 of the second fuse 2. The support frame 45 is located on the side of the second through-hole 43 and on the top surface of the composite support plate 40. The composite support plate 40 also has two side through-holes 46 for the metal conductive sheet 24 to pass through. After the metal conductive sheet 24 has passed through and been installed, the side through-holes 46 can be sealed with epoxy resin. Furthermore, multiple sets of support pillars can be provided in the first bottom cavity 63. Each support pillar is supported between the bottom surface of the composite arc plate 50 and the bottom plate of the lower shell 6 to increase structural stability. There is a spacing between the multiple sets of support pillars, and the first bottom cavity 63 is filled with arc-extinguishing medium. In this embodiment, the bottom of the composite arc track plate 50 has multiple first support pillars 53 protruding downwards towards the lower shell 6, with a spacing between adjacent first support pillars 53. Multiple second support pillars 64 protrude from the interior of the lower shell 6, corresponding to the first support pillars 53. When the middle shell 5 and the lower shell 6 are connected, the first support pillars 53 abut against and are supported on the corresponding second support pillars 64. The first bottom cavity 63 is filled with arc-extinguishing medium. The combination of the first support pillars 53 and the second support pillars 64 forms a support for the middle shell 5. The support pillars create a hollow section, which, compared to sheet-like or block-shaped support components, does not affect the filling of the first bottom cavity 63 with arc-extinguishing medium. Alternatively, the first support pillars 53 on the composite arc track plate 50 can be deformed into an independent bracket directly placed in the lower shell 6, eliminating the second support pillars 64 on the lower shell 6. If the second fuse 2 is housed in the first bottom cavity 63, multiple spaced brackets can also protrude from the top of the composite support plate 40, with each bracket abutting against the inner wall of the top cover 44 for support.

[0024] Because the composite support plate 40 and the composite arc plate 50 are configured with through holes (second through hole 43 and third through hole 58, etc.) around the fusible element (first conductor 11, first fusible element 12 and part of the conductive plate 13) in the first fuse 1, the metal parts inside the first fuse 1 can directly contact and wrap a larger mass of arc-extinguishing medium (quartz sand), which will help dissipate heat from the metal fuse piece of the first fuse 1. This allows the minimum conductive cross-sectional area of ​​the fusible element of the first fuse 1 to be made smaller, while still achieving the ability to achieve the rated current of normal load. At the same time, when a sudden short circuit current occurs, it can melt and trigger the arc more sensitively than structures that require a larger conductive cross-sectional area of ​​the fuse piece to be wrapped with a small amount of quartz sand or not wrapped with quartz sand. For low fault currents, because the fusible element is designed with conventional solder low eutectic effect points, after long-term heat accumulation, it is protected by quartz sand coverage, resulting in less solder oxidation, and can also melt and trigger the arc. Thus, the hybrid fuse of this structure design can achieve faster identification and protection for lower overload currents in the circuit.

[0025] A cavity B containing the first fuse is formed within the inner cavity of the housing, and a second fuse 2 is placed within the inner cavity B containing the first fuse, forming a composite structure in which one fuse cavity contains another fuse. The entire breaking assembly is also built into the inner cavity of the housing, reducing the volume and maximizing the filler space of the fuse, thereby achieving better cooling and arc extinguishing effects.

[0026] In the composite arc plate 50, two sets of positioning pins 55 are provided in the area outside the third through-hole 58, corresponding to the positions of the first conductor 11 and the conductive plate 13. In this embodiment, each set has two positioning pins 55. Positioning holes are provided on the first conductor 11 and the conductive plate 13 respectively, corresponding to the positioning pins 55. The positioning hole on the first conductor is defined as the first positioning through hole 111, and the positioning through hole on the conductive plate 13 is defined as the second positioning through hole 131. When the positioning pins 55 are inserted into the corresponding positioning through holes, the first conductor 11 and the conductive plate 13 are positioned on the composite arc plate 50. The first conductor 11 and the conductive plate 13 are positioned on the composite arc plate 50 by the positioning pin 55, which realizes their tensile, compressive and bending resistance, and facilitates production and assembly. At the same time, it is also conducive to the stable fixing of the distance between the first conductor 11 and the conductive plate 13. Since the two fixing points are designed to be set as close as possible, the fluctuation of the distance between the two copper busbar electrode endpoints caused by the different coefficients of thermal expansion and contraction of the plastic shell and the electrode copper busbar (first conductor 11 and conductive plate 13) due to the temperature change of the working environment can be reduced. This helps to reduce the cyclic bending force of the fusible element of the first fuse caused by the external temperature change, improve the product life and resistance to thermal cycling, so as to adapt to the wind, solar and energy storage system in areas with large day and night temperature differences.

[0027] In addition, the composite arc plate 50 has a boss 56 at the position of the punching component 3, and the isolation cover 71 is located above the boss 56. The boss 56 has at least two first connecting holes 561 around its circumference. The composite support plate 40 is located on top of the boss 56. The composite support plate 40 has a second connecting hole 47 located above each of the first connecting holes 561. The cover of the isolation cover 71 has a third connecting hole 712 located above the first connecting hole 561. A fourth connecting hole 721 can also be provided on the sealing gasket 72. The isolation cover 71, the composite support plate 40 and the composite arc plate 50 can be connected by passing screws (not shown in the figure) through the third connecting hole 712, the fourth connecting hole 721, the second connecting hole 47 and the first connecting hole 561 in sequence. The boss 56 may be provided with a limiting groove 562 for the conductive plate 13 to be embedded and limited. The limiting groove 562 is located above the guide groove 51, and the first connecting hole 561 is located outside the limiting groove. The two sides of the boss 56 form notches 563 for the conductive plate 13 to pass through. The conductive plate 13 can cooperate with the notch 563 to form a stop part 132. The stop part 132 can seal and stop the conductive plate 13 on the notch 563 when it is limited to the composite arc plate 50, ensuring that the conductive plate 13 forms a separation when it enters the cut-off closed space A. Through the above connection structure, the conductive plate 13 passing between the composite support plate 40 and the composite arc plate 50 is fastened to the isolation cover 71, which can improve the insulation isolation strength between the breaking assembly 3 and the conductor 13 to be cut and the outside world, which is beneficial to ensure good electrical safety even after the product is miniaturized.

[0028] The piston 32 includes a piston head 321 and a blade 322. The bottom of the piston head 321 is provided with at least one blade 322 for cutting the conductive plate 13. The composite arc plate 50 is provided with guide grooves 51 corresponding to the number of blades 322. The guide grooves 51 are fitted with the shape of each blade 322, thus preventing the piston 32 from deviating during its downward movement. The conductive plate 13 may have a pre-cutting portion 133 located below the blades 322. The blades 322 pass downwards past the pre-cutting portion 133 and insert into the guide grooves 51, cutting off the pre-cutting portion 133 as they move downwards. There is a partition wall 57 between adjacent guide grooves 51. The partition wall 57 can form a guide and also form a separation in the cavity. The top of the partition wall 57 is recessed with a fixing hole (not shown in the figure). The part of the conductive plate 13 corresponding to the breaking component 3 is mounted on the partition wall 57. The pre-breaking part 133 is located between the partition walls 57. The conductive plate 13 may be provided with a fixing hole (not shown in the figure). The conductive plate 13 is positioned by passing screws through the fixing holes on the conductive plate and the partition wall in sequence.

[0029] In this embodiment, the bottom of the piston head 321 is provided with three parallel blades 322, and the composite arc plate 50 is provided with three corresponding guide grooves 51. At least one protrusion (not shown in the figure) can be provided on the outer surface of the blades 322 in the piston 32, and the boss 56 is provided with a limiting notch for limiting the protrusion. The piston 32 is limited on the middle shell 5 by the protrusion, so that the blades 322 do not contact the conductive plate 13 when the piston is not thrusting downwards, and the protrusion can be deflected when the piston 32 thrusts downwards. After the conductive plate 13 is broken by the downward thrusting blades 322, it enters the guide groove 51 and can be bent and squeezed into the pre-set gap in the guide groove (not shown in the figure). The guide groove 51, together with the arc extinguishing chamber 61, not only guides the conductive plate 13 (copper busbar) but also improves the cooling and extinguishing speed of the arc after the arc is cut off, and accelerates the transfer of all current to the fuse 2 for fusing protection.

[0030] With the above structure, the hybrid fuse of the present invention has the following advantages: (1) The hybrid fuse combines the first fuse and the second fuse to form a product with low power consumption, large rated value and can safely disconnect and protect against high and low fault currents, even low fault currents as low as 1.2 times the rated current, while also taking into account faster disconnection protection when the fault current is high. (2) The hybrid fuse is formed by combining the upper shell, middle shell and lower shell to form a shell with an inner cavity. The middle shell has a composite arc track plate, the upper shell has a composite support plate, and the lower shell integrates the arc extinguishing chamber and the chamber of the first fuse and is fitted with the middle shell. The first conductor and the conductive plate are limited in the space where the composite arc track plate and the composite support plate are fitted together. The composite arc track plate integrates the arc ignition and arc extinguishing guide groove after the arc breaking component is cut, the limiting, support and fixing of the first fuse as a whole, and the shell into one. These reduce the number of parts, simplify the corresponding number of molds and improve production efficiency. (3) After the fuse breaking assembly and the arc extinguishing chamber are isolated as a whole in the housing cavity of the hybrid fuse, the outer cavity of the first fuse is formed. The second fuse is set in the cavity of the first fuse, forming a composite structure in which the inner cavity of one fuse contains another fuse, which reduces the volume and maximizes the filling space of the fuse; and heats up through direct contact with the third through-hole and fillers such as quartz sand, achieving better cooling and arc extinguishing effect, which is conducive to product miniaturization.

[0031] (4) The second fuse is a complete fuse. Its fusible element is located inside the insulating shell and is filled with arc-extinguishing medium. It can be easily installed inside the shell of the hybrid fuse. At the same time, since the outside of the insulating shell is also filled with quartz sand, the hybrid fuse shell will not be damaged when a fault current occurs. In addition, the outer periphery of the entire breaking assembly is wrapped with arc-extinguishing medium (quartz sand). The isolation shell is fixed by the external quartz sand and absorbed by the impact force of the quartz sand. After the superimposed protection of the quartz sand and the shell of the hybrid fuse, the breaking assembly is not easy to burst and fail when the gas is driven to work. The overall structure is reliable, safe and explosion-proof, which improves the product quality and safety.

[0032] The above embodiments and figures are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A hybrid fuse, comprising a first fuse, a tripping assembly, and a second fuse disposed within a housing, wherein the first fuse includes a first conductor, a first fusible element, and a conductive plate, the tripping assembly is located above the conductive plate, the first conductor is connected in series with the conductive plate via the first fusible element, and the second fuse is connected in parallel with the branch containing the first fuse; when the circuit is normally conducting, most of the current flows through the first fuse, and a small portion of the current flows through the branch containing the second fuse; when a fault current occurs, the first fusible element melts and arcs, simultaneously generating an electrical signal to trigger the tripping assembly to cut off the conductive plate, the current is transferred to the branch containing the second fuse, and the second fuse melts and interrupts the fault current; characterized in that: The shell has a cavity, and the shell includes an upper shell, a middle shell and a lower shell. The middle shell has a composite arc plate, the upper shell has a composite support plate, a conductive plate and a first conductor are mounted on the composite arc plate, and the breaking assembly includes a gas generator and a piston. The composite arc plate is provided with a guide groove that can guide the piston to move downward. The lower shell is provided with an arc extinguishing chamber corresponding to the guide groove. When the piston has not yet moved downward, it is limited above the conductive plate. An isolation cover is installed above the composite arc plate, which can be placed outside the breaking assembly. The interior of the isolation cover, together with the conductive plate at its bottom, the composite arc plate, the guide groove, and the arc-extinguishing chamber of the lower shell, constitutes the cutting closed space for the breaking assembly to perform downward cutting. The part of the internal cavity of the shell located outside the isolation cover and the cutting closed space forms the inner cavity where the first fuse is located. The second fuse is located in the inner cavity where the first fuse is located. The inner cavity where the first fuse is located is filled with arc-extinguishing medium.

2. A hybrid fuse as described in claim 1, characterized in that: The composite support plate is located above the composite arc plate. The composite support plate has a first through-hole through which the piston can pass. The isolation shell forms a shell with a bottom opening. The interior of the isolation shell forms a gas-generating chamber. The top of the isolation shell has a top groove for accommodating the gas generator. The piston is inserted into the isolation shell and pushed downward by the driving force generated by the gas generator. The piston passes downward through the first through-hole to the conductive plate. The guide groove is located on the side of the composite arc plate corresponding to the breaking assembly. The composite arc plate has a first partition that separates the side with the guide groove from the side located in the inner cavity of the first fuse. The arc-extinguishing chamber is located on the side of the lower shell corresponding to the breaking assembly. The lower shell has a second partition that separates the side with the arc-extinguishing chamber from the side located in the inner cavity of the first fuse. When the middle shell and the lower shell are connected, the first partition and the second partition combine to form a lower baffle wall. The lower baffle wall isolates the cut-off closed space and the inner cavity of the first fuse.

3. A hybrid fuse as described in claim 1, characterized in that: The first bottom cavity is defined as the side of the inner cavity where the first fuse is located in the lower shell. The second fuse is mounted in the middle shell or the first bottom cavity. The outer side of the second fuse is filled with an arc-extinguishing medium, which is quartz sand.

4. A hybrid fuse as described in claim 1 or 3, characterized in that: The second fuse includes an insulating shell with end caps at both ends. A fusible element is provided inside the insulating shell along its length and connected between the two end caps. The insulating shell is filled with an arc-extinguishing medium. The two ends of the first fuse are defined as a first end electrode and a second end electrode, respectively. One end cap of the second fuse is connected to the part of the first end electrode located inside the cavity of the first fuse through a metal conductive sheet. The other end cap is connected to the part of the second end electrode located inside the shell cavity through a metal conductive sheet.

5. A hybrid fuse as described in claim 4, characterized in that: The second fuse is mounted inside the middle shell and located above the composite support plate. The composite support plate has two side through holes for metal conductive sheets to pass through. After the metal conductive sheets have passed through and the installation is completed, the side through holes are sealed with epoxy resin. The first bottom cavity has multiple sets of support pillars, each of which is supported between the bottom surface of the composite arc plate and the bottom plate of the lower shell. There is a gap between the multiple sets of support pillars, and the first bottom cavity is filled with arc extinguishing medium.

6. A hybrid fuse as described in claim 1 or 2, characterized in that: Both the upper shell and the middle shell are hollow shells. The composite arc plate is located near the top of the middle shell. The outer side wall of the middle shell forms a retaining edge on the outer periphery of the composite arc plate. The composite support plate is located at the bottom of the upper shell. The bottom surface of the composite support plate has a protruding strip that can be embedded in the inner side of the retaining edge for limiting. The composite support plate and the composite arc plate are interlocked when the upper shell and the middle shell are connected and combined. The first conductor and the conductive plate connected to the composite arc plate are located between the two protruding strips and also between the composite support plate and the composite arc plate. The composite support plate has a second through-hole that communicates with the middle shell for the arc extinguishing medium. The isolation cover is located inside the upper shell. The bottom of the isolation cover is located on the composite support plate and outside the first through-hole. A sealing gasket or sealant is provided between the bottom of the isolation cover and the composite support plate. The composite arc plate has a third through-hole that communicates with the lower shell in the area corresponding to the first conductor, the first fusible element, and the conductive plate in the cavity where the first fuse is located.

7. A hybrid fuse as described in claim 6, characterized in that: In the composite arc plate, two sets of positioning pins are provided in the area outside the third through-hole, corresponding to the positions of the first conductor and the conductive plate. The first conductor and the conductive plate are respectively provided with positioning through holes corresponding to the positioning pins. When the positioning pins are inserted into the positioning through holes, the first conductor and the conductive plate are positioned on the composite arc plate.

8. A hybrid fuse as described in claim 6, characterized in that: The composite arc plate has a boss at the position of the punching component, and the isolation cover is located above the boss. At least two first connecting holes are provided around the boss. The composite support plate is located on top of the boss. The composite support plate has a second connecting hole corresponding to each of the first connecting holes. The cover of the isolation cover has a third connecting hole corresponding to the first connecting hole. The isolation cover, the composite support plate, and the composite arc plate are fastened together by passing screws through the third connecting hole, the second connecting hole, and the first connecting hole in sequence.

9. A hybrid fuse as described in claim 8, characterized in that: The boss has a limiting groove located above the guide groove for the conductive plate to be embedded and limited. The two sides of the boss form notches for the conductive plate to pass through. The conductive plate fits into the notches to form a stop, and the stop seals and stops on the notches.

10. A hybrid fuse as described in claim 1, characterized in that: The piston includes a piston head and a blade. The bottom of the piston head is provided with at least one blade for cutting the conductive plate. The composite arc plate is provided with guide grooves corresponding to the number of blades. The guide grooves are matched with the shape of each blade. The conductive plate is provided with a pre-cutting part located below the blade. After the blade moves downward past the pre-cutting part, it inserts into the guide groove and cuts the pre-cutting part. There is a partition wall between adjacent guide grooves. The part of the conductive plate corresponding to the punching component is mounted on the partition wall, and the pre-cutting part is located between the partition walls.

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