Circuit protection structure and excitation fuse

Abstract

The invention provides a circuit protection structure and an excitation fuse, and relates to the technical field of low-voltage electric appliances. The circuit protection structure comprises a shell, an igniter, a piston and a conductive part, the igniter, the piston and the conductive part are arranged in the shell, a first cavity and a second cavity connected with the end of the first cavity are formed in the shell, the first cavity and the second cavity extend in the movement direction of the piston, and the igniter is located on the side, away from the second cavity, of the first cavity. The conductive part is located on the side, away from the first cavity, of the second cavity, the cross section area of the first cavity is kept unchanged, and the cross section area of the second cavity is larger than that of the first cavity; the piston comprises a first piston part, and the first piston part is matched with the first cavity before the conductive part is cut off by the piston; and after the conductive piece is cut off by the piston, the first piston part is separated from the first cavity, so that the first cavity is communicated with the second cavity. According to the circuit protection structure, the requirement on the strength of the shell can be reduced on the premise that the conductive piece is cut off.

Description

Technical Field

[0001] This application relates to the field of low-voltage electrical technology, and more specifically, to a circuit protection structure and an excitation fuse. Background Technology

[0002] The circuit protection structure is an important component of the excitation fuse product. Its main function is to promptly disconnect the protected circuit when a fault occurs. The circuit protection structure generally includes a housing, an igniter housed within the housing, a piston, and a conductive element. The conductive element is connected in series with the protected circuit. The igniter releases high-pressure gas into the explosion chamber housing the piston when an abnormal current occurs, pushing the piston to cut off the conductive element, thereby disconnecting the protected circuit.

[0003] In existing circuit protection structures, the explosion chamber within the housing is cylindrical, and correspondingly, the portion of the piston that seals against the explosion chamber is also cylindrical. Even after the piston cuts off the conductive components, the driving force provided by the high-pressure gas to the piston remains significant, resulting in a large impact force when the piston strikes the bottom of the housing within the explosion chamber. If the strength in this area of ​​the housing is insufficient, it can cause cracking, gas leakage, and affect the function of the arc-extinguishing structure. Therefore, existing circuit protection structures require extremely high strength in the area of ​​the housing corresponding to the bottom of the explosion chamber. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of the prior art by providing a circuit protection structure and an excitation fuse that can reduce the requirements for housing strength while ensuring the disconnection of conductive components.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: One aspect of this application provides a circuit protection structure, including: a housing, an igniter disposed within the housing, a piston, and a conductive element. The housing has a first cavity and a second cavity connected to an end of the first cavity. The first cavity and the second cavity extend along the movement direction of the piston. The igniter is located on the side of the first cavity away from the second cavity, and the conductive element is located on the side of the second cavity away from the first cavity. The cross-sectional area of ​​the first cavity remains unchanged, and the cross-sectional area of ​​the second cavity is larger than that of the first cavity. The piston includes a first piston portion. Before the piston cuts off the conductive element, the first piston portion engages with the first cavity. After the piston cuts off the conductive element, the first piston portion separates from the first cavity, so that the first cavity communicates with the second cavity.

[0006] Optionally, the piston may further include a second piston portion connected to the first piston portion, wherein the cross-sectional area of ​​the second cavity remains unchanged, and the second piston portion cooperates with the second cavity.

[0007] Optionally, the piston also includes a second piston portion connected to the first piston portion, and the housing also has a third cavity, which is connected to the end of the second cavity away from the first cavity. The cross-sectional area of ​​the third cavity remains unchanged, and the second piston portion cooperates with the third cavity.

[0008] Optionally, the housing also has a third cavity, which is connected to the end of the second cavity away from the first cavity. The cross-sectional area of ​​the third cavity is equal to the cross-sectional area of ​​the first cavity, and the third cavity mates with the first piston portion.

[0009] Optionally, the piston further includes a cutting portion connected to the side of the first piston portion facing the conductive element. The conductive element includes a fixed portion and a weak portion, with two adjacent fixed portions connected by the weak portion. The cutting portion is used to cut off the weak portion or to cut off the connection between the weak portion and the fixed portion.

[0010] Optionally, the piston can abut against the fixed part of the conductive element after the conductive element is cut off.

[0011] Optionally, the housing also has a mounting cavity, which is connected to the end of the first cavity. The cross-sectional area of ​​the mounting cavity is smaller than that of the first cavity, and the igniter is embedded in the mounting cavity.

[0012] Optionally, a first sealing ring is fitted onto the first piston portion, and the first sealing ring is used to achieve a sealing fit between the first piston portion and the first cavity.

[0013] Optionally, a first sealing ring is fitted onto the first piston portion to achieve a sealing fit between the first piston portion and the first cavity, and a third sealing ring is fitted onto the second piston portion to achieve a sealing fit between the second piston portion and the second cavity.

[0014] In another aspect of the embodiments of this application, an excitation fuse is provided, including the circuit protection structure as described in any of the above.

[0015] The beneficial effects of this application include: This application provides a circuit protection structure, including: a housing, an igniter disposed within the housing, a piston, and a conductive element. The housing has a first cavity and a second cavity connected to the end of the first cavity. The first and second cavities extend along the direction of piston movement. The igniter is located on the side of the first cavity away from the second cavity, and the conductive element is located on the side of the second cavity away from the first cavity. The cross-sectional area of ​​the first cavity remains constant, while the cross-sectional area of ​​the second cavity is larger than that of the first cavity. The piston includes a first piston portion. Before the piston cuts off the conductive element, the first piston portion engages with the first cavity. After the piston cuts off the conductive element, the first piston portion separates from the first cavity, thereby connecting the first cavity with the second cavity. This circuit protection structure, by providing a first and second cavity within the housing, divides the piston's movement process into at least two stages. In the first stage, the igniter generates high-pressure gas and releases it into the first cavity. The piston, propelled by the high-pressure gas, quickly and forcefully cuts off the conductive element. In the second stage, the high-pressure gas diffuses into the larger second cavity, rapidly reducing the pressure on the piston and gradually decreasing its kinetic energy. Upon reaching the final position, the impact on the piston's limiting structure is minimal. Even if the piston directly impacts the casing, the strength requirements for that part of the casing will be significantly reduced. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the circuit protection structure provided in the embodiments of this application when the piston is in its initial position; Figure 2 for Figure 1 A magnified view of a portion of point A in the middle; Figure 3 A schematic diagram of the circuit protection structure provided in this application embodiment when the piston is between the initial position and the intermediate position; Figure 4 A schematic diagram of the circuit protection structure provided in this application embodiment when the piston is in the middle position; Figure 5 One of the schematic diagrams of the circuit protection structure provided in the embodiments of this application when the piston is in the terminated position; Figure 6 One of the schematic diagrams of the circuit protection structure provided in the embodiments of this application when the piston is in the second stage; Figure 7A second schematic diagram of the circuit protection structure provided in this application embodiment when the piston is in the terminated position; Figure 8 A second schematic diagram of the circuit protection structure provided in this application embodiment when the piston is in the second stage; Figure 9 This is one of the schematic diagrams of the piston structure in the circuit protection structure provided in the embodiments of this application; Figure 10 This is a second schematic diagram of the piston structure in the circuit protection structure provided in the embodiments of this application.

[0018] Icons: 10 - Circuit protection structure; 11 - Housing; 111 - First cavity; 112 - Second cavity; 113 - Third cavity; 114 - Mounting cavity; 12 - Igniter; 13 - Piston; 131 - First piston section; 1311 - Gas storage cavity; 132 - Second piston section; 133 - First annular groove; 134 - Second annular groove; 135 - Third annular groove; 136 - Cut-off section; 14 - Conductive component; 141 - Fixing section; 142 - Weak section; 151 - First sealing ring; 152 - Second sealing ring; 153 - Third sealing ring. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. It should be noted that, unless otherwise specified, the various features in the embodiments of this application can be combined with each other, and the combined embodiments are still within the protection scope of this application.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] In existing circuit protection structures, the explosion chamber containing the piston within the housing is cylindrical, and correspondingly, the portion where the piston seals against the explosion chamber is also cylindrical. Even after the piston cuts off the conductive components, the driving force provided by the high-pressure gas to the piston remains significant, resulting in a large impact force when the piston strikes the bottom of the housing within the explosion chamber. If the strength in this area of ​​the housing is insufficient, it can cause cracking, gas leakage, and affect the function of the arc-extinguishing structure. Therefore, existing circuit protection structures require extremely high strength in the area of ​​the housing corresponding to the bottom of the explosion chamber.

[0025] To address the aforementioned technical problems, one aspect of the embodiments of this application is described below. Figure 1 and Figure 2 A circuit protection structure 10 is provided, comprising: a housing 11, an igniter 12 disposed within the housing 11, a piston 13, and a conductive element 14. The igniter 12 generates and releases high-pressure gas upon the occurrence of a fault. The high-pressure gas contacts the piston 13, driving the piston 13 to move towards and disconnect the conductive element 14. Both ends of the conductive element 14 are connected to the protected circuit; when the conductive element 14 is disconnected, the protected circuit is also broken.

[0026] Specifically, the housing 11 has a first cavity 111 and a second cavity 112 connected to the end of the first cavity 111. The first cavity 111 and the second cavity 112 extend along the direction of movement of the piston 13. The igniter 12 is located on the side of the first cavity 111 away from the second cavity 112, and the conductive element 14 is located on the side of the second cavity 112 away from the first cavity 111. The piston 13 is disposed in the first cavity 111 and the second cavity 112 and moves linearly within the first cavity 111 and the second cavity 112. The igniter 12, the first cavity 111, the second seal, and the conductive element 14 are distributed sequentially along the direction of movement of the piston 13. The cross-sectional area of ​​the first cavity 111 remains unchanged, and the cross-sectional area of ​​the second cavity 112 is larger than that of the first cavity 111. It should be noted that the cross-sectional area mentioned in this document refers to the area of ​​the cross section perpendicular to the direction of movement of the piston 13.

[0027] The piston 13 includes a first piston portion 131, which engages with a first cavity 111 and is movable within the first cavity 111 and a second cavity 112. Before the piston 13 cuts off the conductive element 14, the first piston portion 131 engages with the first cavity 111; after the piston 13 cuts off the conductive element 14, the first piston portion 131 moves completely into the second cavity 112 and separates from the first cavity 111, thereby connecting the first cavity 111 and the second cavity 112.

[0028] The movement of piston 13 consists of two stages. For the first stage, please refer to... Figures 2 to 4 The igniter 12 generates high-pressure gas and releases it into the first chamber 111. Driven by the high-pressure gas, the piston 13 moves from its initial position to its intermediate position until the conductive element 14 is completely cut off. During this process, the first piston portion 131 cooperates with the first chamber 111 to seal its outlet, preventing high-pressure gas from entering the second chamber 112. Because the cross-sectional area of ​​the first chamber 111 is small, the diffusion space provided by the first chamber 111 for the high-pressure gas is always small in the first stage. Therefore, the pressure on the piston 13 is always large, and the high-pressure gas provides sufficient force for the piston 13 to cut off the conductive element 14. For the second stage, please refer to... Figure 4 and Figure 5Driven by the high-pressure gas, piston 13 continues to move from the intermediate position to the endpoint. During this process, the first piston section 131 completely separates from the first chamber 111, and the first chamber 111 and the second chamber 112 become connected, allowing the high-pressure gas to enter the second chamber 112. Because the second chamber 112 has a larger cross-sectional area, the high-pressure gas can diffuse rapidly after entering it. Therefore, the pressure on piston 13 decreases rapidly in the second stage, and the kinetic energy of piston 13 gradually decreases. When it reaches the endpoint, the impact on the limiting structure of piston 13 is relatively small. Even if piston 13 directly impacts the housing 11, the strength requirements for that area of ​​the housing 11 are significantly reduced.

[0029] It should be noted that the outlet end of the igniter 12 should face the first cavity 111, so that the high-pressure gas generated by the igniter 12 can smoothly enter the first cavity 111 and push the piston 13 to move on the side of the piston 13 away from the conductive element 14. The structure of the igniter 12 is prior art, and will not be described in detail here.

[0030] To ensure that the piston 13 remains in contact with the first cavity 111 throughout the first stage of movement, the cross-sectional area and shape of the first cavity 111 remain constant; that is, the first cavity 111 is cylindrical (the cross-section is not limited to circular). Correspondingly, the cross-sectional area and shape of the first piston portion 131 of the piston 13 should also remain constant. It can be understood that the contact between the first piston portion 131 and the first cavity 111 means that the outer wall of the first piston portion 131 is in close contact with the inner wall of the first cavity 111 or there is only a small gap. Of course, the piston 13 may also include other piston portions, and the housing 11 may also have other cavities communicating with the first cavity 111 and the second cavity 112. This embodiment does not limit this, as long as the rapid release of high-pressure gas can be achieved in the second stage. The cross-sectional area of ​​the second cavity 112 can remain constant, or it can gradually increase or decrease, as long as the rapid release of high-pressure gas can be achieved without interfering with the movement of the piston 13.

[0031] When there are multiple protected circuits, a circuit protection structure 10 can be set for each protected circuit, or only one circuit protection structure 10 can be set. However, the housing 11 of the circuit protection structure 10 should be equipped with multiple sets of igniters 12, pistons 13 and conductive elements 14, and each set of igniters 12, pistons 13 and conductive elements 14 corresponds to one protected circuit.

[0032] Alternatively, please refer to Figures 2 to 5 The piston 13 also includes a second piston portion 132 connected to the first piston portion 131. The cross-sectional area of ​​the second cavity 112 remains unchanged, and the second piston portion 132 can cooperate with the second cavity 112.

[0033] At this point, in the first stage, the second piston 132 engages with the second cavity 112, while the first piston 131 engages with the first cavity 111 initially, then completely disengages from the first cavity 111, but still blocks the outlet of the first cavity 111. In the second stage, the first cavity 111 and the second cavity 112 are connected, and high-pressure gas enters the second cavity 112, while the second piston 132 still engages with the second cavity 112.

[0034] Please refer to the reference. Figure 6 Compared to the design without the second piston 132, the presence of the second piston 132 serves a sealing function, confining the high-pressure gas to the side of the second piston 132 away from the conductive element 14. Therefore, the high-pressure gas will not leak or leak in large quantities from the end of the second cavity 112 away from the first cavity 111.

[0035] It should be noted that, in order to ensure that the piston 13 remains in contact with the second cavity 112 throughout the second stage of movement, the cross-sectional area and cross-sectional shape of the second cavity 112 remain unchanged; that is, the second cavity 112 is cylindrical (the cross-section is not limited to being circular). Correspondingly, the cross-sectional area and cross-sectional shape of the second piston portion 132 of the piston 13 should also remain unchanged.

[0036] Alternatively, please refer to Figure 7 The piston 13 also includes a second piston portion 132 connected to the first piston portion 131. The housing 11 also has a third cavity 113. The third cavity 113 is connected to the end of the second cavity 112 away from the first cavity 111. The cross-sectional area of ​​the third cavity 113 remains unchanged. The second piston portion 132 cooperates with the third cavity 113.

[0037] In the first stage, the first piston 131 engages with the first cavity 111, then completely disengages from it, but still blocks the outlet of the first cavity 111. The second piston 132 is either entirely within the second cavity 112, entirely within the third cavity 113, or partially within both. In the second stage, the first cavity 111 and the second cavity 112 are connected, allowing high-pressure gas to enter the second cavity 112. The second piston 132 then engages with the third cavity 113. This design also confines the high-pressure gas to the side of the second piston 132 furthest from the conductive element 14, preventing leakage or excessive leakage of high-pressure gas from the end of the third cavity 113 furthest from the first cavity 111.

[0038] It should be noted that, in order to ensure that the piston 13 remains in contact with the third chamber 113 throughout the second stage of its movement, the cross-sectional area and shape of the third chamber 113 remain unchanged; that is, the third chamber 113 is cylindrical (the cross-section is not limited to being circular). Correspondingly, the cross-sectional area and shape of the second piston portion 132 of the piston 13 should also remain unchanged. The cross-sectional area of ​​the third chamber 113 can be greater than, less than, or equal to the cross-sectional area of ​​the first chamber 111. Simultaneously, the cross-sectional area of ​​the third chamber 113 can be less than or greater than the cross-sectional area of ​​the second chamber 112. Furthermore, the cross-sectional area of ​​the second chamber 112 is not limited; it can remain constant, or it can gradually increase or decrease, as long as it enables the rapid release of high-pressure gas without interfering with the movement of the piston 13.

[0039] Alternatively, please refer to Figure 8 The housing 11 also has a third cavity 113, which is connected to the end of the second cavity 112 away from the first cavity 111. The cross-sectional area of ​​the third cavity 113 is equal to the cross-sectional area of ​​the first cavity 111, and the third cavity 113 cooperates with the first piston part 131.

[0040] In the first stage, the first piston 131 engages with the first cavity 111, then completely disengages from it, but still blocks the outlet of the first cavity 111. In the second stage, the first cavity 111 and the second cavity 112 are connected, allowing high-pressure gas to enter the second cavity 112, where the first piston 131 engages with the third cavity 113. This design also confines the high-pressure gas within the second cavity 112, preventing leakage or excessive leakage from the end of the third cavity 113 away from the first cavity 111.

[0041] It should be noted that both the first cavity 111 and the third cavity 113 are cylindrical, and their cross-sectional areas and shapes are identical. Correspondingly, the first piston portion 131 of the piston 13 is also cylindrical.

[0042] Alternatively, please refer to Figure 3 A first sealing ring 151 is fitted on the first piston part 131. The first sealing ring 151 is used to achieve a sealing fit between the first piston part 131 and the first cavity 111.

[0043] Please refer to the reference. Figure 9 The first sealing ring 151 surrounds the first piston portion 131 and is clamped between the first piston portion 131 and the first cavity 111. Before the first piston portion 131 opens the outlet of the first cavity 111, the high-pressure gas will not leak into the second cavity 112, so that the high-pressure gas can provide greater driving force to the piston 13 in the first stage.

[0044] To facilitate the installation of the first sealing ring 151, optionally, the side wall of the first piston portion 131 is provided with a first annular groove 133, and the first sealing ring 151 is disposed in the first annular groove 133 and exposed in the first annular groove 133.

[0045] Please refer to Figure 8 If the first piston portion 131 also mates with the third cavity 113, the side wall of the first piston portion 131 may also be provided with a second sealing ring 152, which is used to achieve a sealing fit between the first piston portion 131 and the third cavity 113.

[0046] Optionally, the side wall of the first piston portion 131 is further provided with a second annular groove 134, and the second sealing ring 152 is disposed in the second annular groove 134 and exposed in the second annular groove 134.

[0047] Please refer to Figure 3 If the piston 13 further includes a second piston portion 132, a third sealing ring 153 can be fitted onto the second piston portion 132; if the second piston portion 132 mates with the second cavity 112, the third sealing ring 153 is used to achieve a sealed connection between the second piston portion 132 and the second cavity 112; please refer to Figure 7 If the second piston portion 132 mates with the third cavity 113, the third sealing ring 153 is used to achieve a sealed connection between the second piston portion 132 and the third cavity 113.

[0048] Optionally, the side wall of the second piston portion 132 is further provided with a third annular groove 135, and the third sealing ring 153 is disposed in the third annular groove 135 and exposed in the second annular groove 134.

[0049] Alternatively, please refer to Figure 2 The housing 11 also has a mounting cavity 114, which is connected to the end of the first cavity 111. The cross-sectional area of ​​the mounting cavity 114 is smaller than that of the first cavity 111. The igniter 12 is embedded in the mounting cavity 114.

[0050] The igniter 12 is embedded in the mounting cavity 114. The igniter 12 can seal the side of the first cavity 111 away from the second cavity 112, allowing the high-pressure gas generated by the igniter 12 to directly enter the first cavity 111 without leakage from the side away from the second cavity 112. The cross-sectional area of ​​the mounting cavity 114 is smaller than that of the first cavity 111, which facilitates the convergence of high-pressure gas and its smooth entry into the first cavity 111. This allows the high-pressure gas to provide a greater driving force to the piston 13 in the first stage.

[0051] Optionally, a gas storage chamber 1311 is provided on the end face of the first piston portion 131 away from the second piston portion 132, and the gas storage chamber 1311 corresponds to the gas outlet position of the igniter 12. The arrangement of the gas storage chamber 1311 makes it easier for high-pressure gas to drive the piston 13 to move in the initial position.

[0052] Alternatively, please refer to Figure 9 and Figure 10 The center lines of the first piston section 131 and the second piston section 132 coincide with each other. Both the first piston section 131 and the second piston section 132 are centrally symmetrical. This arrangement can make the force on the piston 13 more uniform.

[0053] Alternatively, please refer to Figure 2 and Figure 3 The piston 13 also includes a cutting portion 136, which is connected to the side of the first piston portion 131 facing the conductive member 14. The cutting portion 136 is the part of the piston 13 that contacts the conductive member 14 and is used to cut off the conductive member 14. It should be noted that if a second piston portion 132 exists, the first piston portion 131, the second piston portion 132, and the cutting portion 136 are distributed sequentially along the direction of movement of the piston 13.

[0054] To ensure the conductive element 14 can be easily cut off, the conductive element 14 includes a fixed portion 141 and a weak portion 142. Two adjacent fixed portions 141 are connected via the weak portion 142, and the ends of the two fixed portions 141 furthest from the weak portion 142 are respectively used to connect to the protected circuit. The cutting portion 136 is used to cut off the weak portion 142 or to cut off the connection between the weak portion 142 and the fixed portion 141. The weak portion 142 is more prone to fracture after being impacted than the fixed portion 141. The thickness of the weak portion 142 can be reduced locally or entirely to make it easier to cut off, or to make the connection between the weak portion 142 and the fixed portion 141 easier to cut off.

[0055] Optionally, the cross-sectional area of ​​the cut-off portion 136 gradually decreases along the direction of movement of the piston 13.

[0056] This design ensures that the cutting part 136 has sufficient strength and will not easily break when cutting the conductor. On the other hand, it also allows for a smaller contact area between the cutting part 136 and the conductive element 14, enabling greater pressure to be applied to the conductive element 14 so that it can be cut.

[0057] Optionally, the cutting portion 136 is connected to the side of the second piston portion 132 away from the first piston portion 131, and the cross-sectional area of ​​the cutting portion 136 is smaller than the cross-sectional area of ​​the second piston portion 132, so that the cutting portion 136 can move within the cavity where the second piston portion 132 is located before contacting the conductive member 14.

[0058] Alternatively, please refer to Figure 9 and Figure 10 The center lines of the first piston part 131 and the cutting part 136 coincide with each other. Both the first piston part 131 and the cutting part 136 are centrally symmetrical. This arrangement can make the force on the piston 13 more uniform.

[0059] Alternatively, please refer to Figure 5 The piston 13 can abut against the fixing part 141 of the conductive element 14 after the conductive element 14 is cut off. By using a conductive element to limit the piston 13 instead of using the housing 11 to limit it, the strength requirements of the housing 11 can be further reduced.

[0060] Optionally, at least one fixing portion 141 of the conductive member 14 extends to the side of the second cavity 112 away from the first cavity 111, and the end face of the second piston portion 132 can abut against the fixing portion 141.

[0061] When the end face of the second piston portion 132 abuts against the surface of the fixed portion 141, the fixed portion 141 applies a force to the piston 13 in the opposite direction of its movement, thereby stopping the piston 13. The fixed portion 141 and the second piston portion 132 are in surface contact, which allows the piston 13 to stop more smoothly and also avoids damage to the surface of the piston 13.

[0062] This embodiment also provides an excitation fuse, including the circuit protection structure 10 as described above.

[0063] This activated fuse has the same structure and beneficial effects as the circuit protection structure 10 in the foregoing embodiments. The structure and beneficial effects of the circuit protection structure 10 have been described in detail in the foregoing embodiments and will not be repeated here.

[0064] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A circuit protection structure, characterized in that, include: The housing (11), the igniter (12), the piston (13) and the conductive element (14) disposed within the housing (11), the housing (11) having a first cavity (111) and a second cavity (112) connected to the end of the first cavity (111), the first cavity (111) and the second cavity (112) extending along the direction of movement of the piston (13), the igniter (12) being located on the side of the first cavity (111) away from the second cavity (112), the conductive element (14) being located on the side of the second cavity (112) away from the first cavity (111), the cross-sectional area of ​​the first cavity (111) remaining unchanged, and the cross-sectional area of ​​the second cavity (112) being larger than the cross-sectional area of ​​the first cavity (111); The piston (13) includes a first piston portion (131). Before the piston (13) cuts off the conductive element (14), the first piston portion (131) cooperates with the first cavity (111). After the piston (13) cuts off the conductive element (14), the first piston portion (131) separates from the first cavity (111) so that the first cavity (111) communicates with the second cavity (112).

2. The circuit protection structure as described in claim 1, characterized in that, The piston (13) further includes a second piston portion (132) connected to the first piston portion (131), the cross-sectional area of ​​the second cavity (112) remains unchanged, and the second piston portion (132) cooperates with the second cavity (112).

3. The circuit protection structure as described in claim 1, characterized in that, The piston (13) further includes a second piston portion (132) connected to the first piston portion (131), and the housing (11) also has a third cavity (113). The third cavity (113) is connected to the end of the second cavity (112) away from the first cavity (111). The cross-sectional area of ​​the third cavity (113) remains unchanged, and the second piston portion (132) cooperates with the third cavity (113).

4. The circuit protection structure as described in claim 1, characterized in that, The housing (11) also has a third cavity (113), which is connected to the end of the second cavity (112) away from the first cavity (111). The cross-sectional area of ​​the third cavity (113) is equal to the cross-sectional area of ​​the first cavity (111), and the third cavity (113) can cooperate with the first piston part (131).

5. The circuit protection structure as described in claim 1, characterized in that, The piston (13) further includes a cutting portion (136), which is connected to the side of the first piston portion (131) facing the conductive member (14). The conductive member (14) includes a fixing portion (141) and a weak portion (142). Two adjacent fixing portions (141) are connected through the weak portion (142). The cutting portion (136) is used to cut off the weak portion (142) or to cut off the connection between the weak portion (142) and the fixing portion (141).

6. The circuit protection structure as described in claim 5, characterized in that, The piston (13) is able to abut against the fixing part (141) of the conductive element (14) after the conductive element (14) is cut off.

7. The circuit protection structure as described in claim 1, characterized in that, The housing (11) also has a mounting cavity (114), which is connected to the end of the first cavity (111). The cross-sectional area of ​​the mounting cavity (114) is smaller than that of the first cavity (111), and the igniter (12) is embedded in the mounting cavity (114).

8. The circuit protection structure as described in claim 1, characterized in that, A first sealing ring (151) is fitted on the first piston part (131), and the first sealing ring (151) is used to achieve a sealing fit between the first piston part (131) and the first cavity (111).

9. The circuit protection structure as described in claim 2, characterized in that, A first sealing ring (151) is fitted on the first piston part (131), and the first sealing ring (151) is used to achieve a sealing fit between the first piston part (131) and the first cavity (111). A third sealing ring (153) is fitted on the second piston part (132), and the third sealing ring (153) is used to achieve a sealing fit between the second piston part (132) and the second cavity (112).

10. An excitation fuse, characterized in that, Includes the circuit protection structure as described in any one of claims 1 to 9.

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