Piston structure and pyrotechnic cutout

Abstract

This utility model relates to the field of fireworks cut-off technology, and particularly to a piston structure and a fireworks cut-off device. The piston structure includes a first part and a second part connected to the first part. The first part is an axially extending columnar structure with an elliptical radial cross-sectional shape. A groove for receiving gas impact is provided on the end face of the first part away from the second part, and the axial extension direction of the groove is consistent with the axial direction of the first part. The radial cross-sectional shape of the groove is circular. Through the above design, the gas flow path and kinetic energy conversion efficiency driven by the piston can be optimized, effectively and quickly cutting off the circuit in a short time and avoiding arcing of the main electrode.

Description

Technical Field

[0001] This utility model relates to the field of circuit protection technology, and in particular to a piston structure and a smoke cut-off device. Background Technology

[0002] While pyrotechnic fuses are widely used in circuit protection, their working principle primarily involves using a gas generator to produce thrust and push a piston structure to cut off the main circuit electrodes, thus achieving protection. Therefore, the piston structure, as a crucial component, mainly functions to seal the high-pressure gas, ensuring that all the high-pressure gas acts on the piston, transferring kinetic energy through it.

[0003] However, the existing piston structure still has bottlenecks in achieving energy conversion and kinetic energy release, making it difficult to quickly cut off the circuit and avoid arcing of the main electrode in a short period of time. Utility Model Content

[0004] This invention provides a piston structure and a pyrotechnic cutter, which can solve at least one problem in the background art to optimize the design and improve the performance of the pyrotechnic cutter.

[0005] In a first aspect, this utility model embodiment provides a piston structure, including a first part and a second part connected to the first part, wherein the first part is a columnar structure extending along the axial direction and its radial cross-sectional shape is elliptical;

[0006] The first part has a groove on its end face away from the second part for receiving gas impact, and the axial extension direction of the groove is consistent with the axial direction of the first part; the radial cross-sectional shape of the groove is circular.

[0007] In some embodiments, the ratio of the major axis dimension W1 of the first portion to the minor axis dimension W2 of the first portion is between 1.2:1 and 1.8:1; the ratio of the axial depth d1 of the groove to the axial height d2 of the first portion is between 1 / 3 and 1 / 2.

[0008] In some embodiments, the ratio of the axial depth d1 of the groove to the axial height d2 of the first portion is between 1 / 3 and 1 / 2.

[0009] In some embodiments, the ratio of the maximum radial cross-sectional area of ​​the first portion to the maximum radial cross-sectional area of ​​the groove is between 3.5 and 4.0, or the ratio of the maximum radial cross-sectional area of ​​the first portion to the maximum radial cross-sectional area of ​​the groove is 3.84:1.

[0010] In some embodiments, a piston cutter is formed at the end of the second portion away from the first portion, and the end face of the piston cutter has a convex structure.

[0011] In some embodiments, the second portion is axially connected to the first portion; the second portion extends along the radial major axis of the first portion to form a strip structure, and its width along the radial minor axis of the first portion is smaller than the major axis dimension of the first portion; a boss and / or reinforcing ribs are provided at the connection between the second portion and the first portion.

[0012] In some embodiments, the radial cross-sectional diameter of the groove varies with the depth of the groove.

[0013] This utility model provides a firework cutter, including: a housing with a stroke cavity formed inside, a driving device, main circuit electrodes, and a piston structure as described in any of the above embodiments;

[0014] The main circuit electrode is inserted into the stroke cavity of the housing, and the piston structure is located in the stroke cavity and on one side of the main circuit electrode; one end of the driving device is placed in the groove, and when the driving device generates high-pressure gas, the piston structure moves in the stroke cavity to break the main circuit electrode, so that the main circuit electrode forms at least one break.

[0015] In some embodiments, at least a portion of the radial cross-sectional shape of the travel cavity is an ellipse adapted to the first portion, and the average wall thickness of the housing along the major axis of the radial cross-section of the travel cavity is greater than the average wall thickness of the housing along the minor axis of the radial cross-section of the travel cavity.

[0016] In some embodiments, the device further includes a melt connected in parallel with the main circuit electrode; the housing also has an arc-extinguishing cavity; at least a portion of the melt is located within the arc-extinguishing cavity, which is filled with an arc-extinguishing medium.

[0017] In some embodiments, a melt pusher is further included, and the housing also has a movable cavity communicating with the stroke cavity. The melt self-extinguishing arc cavity extends through the movable cavity, and the melt pusher is located in the movable cavity. After the piston structure moves in the stroke cavity to break the main circuit electrode, the piston structure continues to move to push the melt pusher to move in the movable cavity and thus cut off the melt.

[0018] The piston structure provided by this utility model can better adapt to the internal spatial layout of the pyrotechnic cutter by optimizing the shape and structure of the piston structure and the groove, thereby improving space utilization and structural strength, optimizing the gas flow path and kinetic energy conversion efficiency driven by the piston, reducing turbulence and energy loss, and effectively generating a pressure difference driving effect, improving kinetic energy release efficiency, accelerating the rapid cut-off of the circuit in a short time and avoiding arcing of the main electrode.

[0019] Furthermore, the piston structure can be further optimized by limiting the ratio of the radial cross-sectional area of ​​the first part of the piston structure and the recess, thereby maximizing energy harvesting and optimizing kinetic energy release. It also helps balance mechanical strength and energy conversion efficiency to adapt to different application scenarios.

[0020] Other features and beneficial effects of this invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing this invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 A perspective view of a piston structure provided in an embodiment of this utility model;

[0023] Figure 2 This is a front view of a piston structure provided in an embodiment of the present invention;

[0024] Figure 3 This is a top view of a piston structure provided in an embodiment of the present invention;

[0025] Figure 4 An exploded perspective view of a fireworks cutter provided in an embodiment of this utility model;

[0026] Figure 5 A cross-sectional view of a pyrotechnic cutter provided in an embodiment of this utility model;

[0027] Figure 6 A 3D view of the main circuit electrodes;

[0028] Figure 7 A three-dimensional view of the melt pusher;

[0029] Figure 8 A three-dimensional diagram of the melt;

[0030] Figure 9 for Figure 5 A magnified view of part A in the image;

[0031] Figure 10 This is a partial cross-sectional view of a fireworks cutter provided in an embodiment of the present invention;

[0032] Figure 11 A partial bottom perspective view of a fireworks cutter provided in an embodiment of this utility model;

[0033] Figure 12 This is a partial exploded perspective view of a fireworks cutter provided in an embodiment of the present invention.

[0034] Figure label:

[0035] 10. Piston structure; 11. First part; 11a. Sealing groove; 12. Second part; 12a. Piston cutter; 12b. Support leg; 12c. Limiting block; 12d. Boss; 12f. Reinforcing rib; 13. Groove; 20. Shell; 20a. Stroke cavity; 20b. Moving cavity; 201b. Slit; 20c. Arc extinguishing cavity; 201c. First region; 202c. Second region; 20d. First gap; 20e. Second gap; 20f. Positioning post; 21. Upper shell; 22. Middle shell; 23. Cover shell; 24. Lower shell; 25. Isolation barrier 26. Inner sleeve; 27. Inner plate; 28. Pressure plate; 30. Drive device; 40. Main circuit electrode; 40a. Disconnect weak section; 40b. Limiting hole; 40c. Limiting protrusion; 22a. Limiting support; 40c. Sealing structure; 50. Melt; 50a. Melt-breaking weak section; 501a. First pre-melting through hole; 502a. Second pre-melting through hole; 50b. Cutting weak section; 501b. Outer protrusion; 50c. Slot; 60. Sealing element; 70. Melt pusher; 71. Support; 72. Fixing part; 73. Protruding column; 74. Protruding ridge. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. The technical features designed in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0037] In the description of this utility model, it should be noted that all terms used in this utility model (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model pertains, and should not be construed as limiting this utility model; it should be further understood that the terms used in this utility model should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this utility model.

[0038] Example 1

[0039] Please see Figures 1-3 This utility model provides a piston structure, which includes a first part 11 and a second part 12 connected to the first part 11;

[0040] The piston structure 10 is made of insulating material and includes a first part 11 and a second part 12 that are connected to each other. When the piston structure 10 is used in a pyrotechnic cutter, the groove 13 of the first part 11 is positioned towards the high-pressure gas release end of the drive device 30.

[0041] The first part 11 is an axially extending columnar structure with an elliptical radial cross-section. Compared to the traditional circular radial cross-section, it offers greater flexibility. The elliptical design maintains compactness in spatially constrained directions (such as the longer width direction) while increasing the area in directions allowing for extension (such as the shorter width direction), achieving local area optimization and improved energy harvesting efficiency. Specifically, the piston surface area of ​​a traditional circular radial cross-section design is uniform, while the piston area of ​​an elliptical design varies. Therefore, when high-pressure gas pushes the piston, the elliptical piston, compared to the circular piston, exhibits advantages. Firstly, the dimensional difference between its longer and shorter widths allows for a more uneven force distribution, which facilitates rapid gas expansion across the piston surface, filling a larger piston area and thus improving energy harvesting efficiency. Secondly, compared to the linear gas flow of a circular piston structure, the elliptical piston structure guides the high-pressure gas to form a specific nonlinear flow path. This path helps reduce turbulence and energy loss during gas flow, making it easier to achieve rapid energy filling and expansion, thereby improving energy harvesting efficiency. Furthermore, due to the differences in cross-sectional shape and area of ​​the elliptical piston structure, different pressures will be formed in different areas when high-pressure gas acts on the piston structure. This pressure difference can generate additional driving force to propel the piston structure 10, enhancing its kinetic energy. The pressure difference driving effect also allows the elliptical piston structure 10 to generate greater kinetic energy conversion efficiency under the same gas pressure. Simultaneously, when the elliptical piston structure is applied to the stroke cavity 20a with the same elliptical cross-section in the pyrotechnic switcher, compared to a circular piston structure applied to the same stroke cavity, it can guide the high-pressure gas to form a spiral flow path, while also reducing turbulent energy loss. Compared to a cylindrical cavity, it can effectively improve gas filling efficiency. Moreover, its combined application allows the piston channel to become a large elliptical cavity after the main circuit electrode 40 is cut off, facilitating the rapid release of residual gas pressure after the main circuit electrode 40 is cut off, avoiding the risk of structural damage due to pressure accumulation, thereby improving the reliability and safety of the equipment.

[0042] For further information, please refer to [link / reference]. Figure 3The ratio of the major axis dimension W1 to the minor axis dimension W2 of the first portion 11 is between 1.2:1 and 1.8:1 to ensure that the piston structure 10 can both guide the movement well and withstand the pressure of high-pressure gas. Specifically, if the ratio is too high, although the piston area can be further increased, its mechanical strength will decrease and it will be prone to deformation under high pressure. If the ratio is too low, although the structural stability will be enhanced, the energy harvesting efficiency will decrease. Therefore, this embodiment can effectively balance mechanical strength and energy harvesting efficiency through its ratio limitation. In particular, when the piston structure 10 is used in high-frequency vibration or thermal expansion applications (such as thermal expansion pyrotechnic cutters), this ratio limitation allows for expansion margins in the minor axis, reducing frictional losses caused by thermal deformation. The ratio of the major axis dimension W1 to the minor axis dimension W2 can be 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, etc. For example, the major axis is 24mm and the minor axis is 16mm, with a ratio of 1.5:1.

[0043] At least one sealing groove 11a is provided on the outer peripheral surface of the first part 11 along the circumferential direction, and a sealing element 60 is fitted in the sealing groove 11a. When the piston structure 10 is installed in the pyrotechnic cutter, the sealing element 60 seals the contact surface between the outer peripheral surface of the piston structure 10 and the pyrotechnic cutter, so as to ensure that all the high-pressure gas released by the drive device 30 acts on the piston structure 10.

[0044] The first portion 11 has a groove 13 on its end face away from the second portion 12. The axial extension direction of the groove 13 is consistent with the axial direction of the first portion 11, and the radial cross-sectional shape of the groove 13 is circular. The groove 13 is used to receive the impact of high-pressure gas and convert it into the kinetic energy of the piston structure 10.

[0045] In this embodiment, the radial cross-sectional diameter of the groove 13 preferably varies with the depth of the groove 13. That is, the radial cross-sectional diameter of the groove 13 is not completely constant (i.e., not cylindrical), but rather the radial cross-sectional diameter along the depth direction decreases (i.e., the axial cross-section is arc-shaped) or the radial cross-sectional diameter along the depth direction remains constant and then decreases (i.e., the axial cross-section is U-shaped), which is beneficial for guiding airflow.

[0046] By designing the radial cross-sectional shape of the recess 13, the vortex effect generated by the high-pressure gas in the recess 13 can reduce the friction of the gas adhering to the combustion gases, lower the starting frictional resistance of the piston structure 10, guide the airflow to concentrate towards the piston axis, reduce lateral energy loss, and accelerate the response speed. Specifically, the circular diameter D of the maximum radial cross-section of the recess 13 is smaller than the minor axis dimension W2. For example, if the minor axis dimension W2 is 16mm, the circular diameter D is 10mm. The combination of the elliptical piston structure 10 and the circular recess 13 further reduces the frictional resistance between the piston structure 10 and surrounding components, improves kinetic energy conversion efficiency, and allows the circular recess 13 to serve as a micro-channel for gas flow, helping the high-pressure gas to more evenly propel the piston structure 10. Due to the presence of the circular recess 13, the wall thickness of local areas on the surface of the piston structure 10 can be adjusted more flexibly to adapt to the mechanical challenges of high-pressure, high-speed operating environments. This design allows for a thicker wall thickness design within a limited space while maintaining the strength of the piston structure 10, thereby improving the durability and reliability of the piston structure 10.

[0047] In this embodiment, the ratio of the maximum radial cross-sectional area of ​​the first portion 11 to the maximum radial cross-sectional area of ​​the groove 13 is preferably between 3.5 and 4.0. More preferably, the ratio of the maximum radial cross-sectional area of ​​the first portion 11 to the maximum radial cross-sectional area of ​​the groove 13 is 3.84:1. Please refer to [link / reference]. Figure 4 The maximum radial cross-sectional area of ​​the first part 11 is S2, and the maximum radial cross-sectional area of ​​the groove 13 is S1.

[0048] The aforementioned area ratio design ensures that the elliptical piston can more effectively capture and concentrate energy when the drive device 30 triggers and generates high-pressure gas. The high-pressure gas first enters the recess 13. Because the area of ​​the ellipse is much larger than the area of ​​the recess 13, the gas can quickly fill and expand throughout the entire elliptical cavity as it propels the piston forward, thereby maximizing energy harvesting. Simultaneously, the piston structure 10 with this area ratio, applied to the stroke cavity 20a with a matching shape, also helps to quickly release residual gas pressure after the main electrode sheet is cut off, avoiding structural damage caused by pressure accumulation.

[0049] Its working principle is as follows: When the piston structure 10 is applied to the pyrotechnic cutter, the high-pressure gas generated by the drive device 30 first enters the groove 13. Since the maximum radial cross-sectional area of ​​the first part 11 is more than 3.5 times the maximum radial cross-sectional area of ​​the groove 13, the high-pressure gas rapidly fills and expands to the entire surface of the piston structure 10 facing the groove 13 under pressure, forming a pressure difference driving effect. The high-pressure gas can be more effectively captured and concentrated by the piston structure 10. This increases the effective force-bearing area of ​​the gas pushing the piston, thereby efficiently converting the gas into the kinetic energy of the piston, pushing the piston to move at high speed along the axial direction (the speed can reach more than 1.5 times that of a traditional circular piston design).

[0050] Further, please refer to Figure 2 The ratio of the axial depth d1 of the recess 13 to the axial height d2 of the first part 11 is between 1 / 3 and 1 / 2. In the design of the recess 13 and the piston structure 10, if the ratio is too small, there will be insufficient space for gas to accumulate in the recess 13, which may lead to insufficient kinetic energy and reduced breaking efficiency of the piston structure 10. If the ratio is too large, it will increase the frictional resistance of gas flow, which is not conducive to the effective collection of energy. Therefore, by limiting the ratio of the depth of the recess 13 to the height of the first part 11 and combining the area ratio of the two, this embodiment can improve the energy conversion efficiency of the piston structure 10 and reduce energy loss without changing the initial kinetic energy provided by the drive device 30. This ensures that the piston structure 10 obtains sufficient kinetic energy to quickly and efficiently cut off the main circuit electrode 40, while also effectively guaranteeing the mechanical strength of the structure.

[0051] Please continue reading. Figure 1 , Figure 2 The second part 12 is axially connected to the first part 11 and can be integrally formed. The second part 12 extends along the radial major axis of the first part 11 to form a strip structure, and its width along the radial minor axis of the first part 11 is smaller than the major axis dimension of the first part 11. This design further saves space, allowing more of the kinetic energy of the high-pressure gas to be released within the space of the piston structure 10. More preferably, a boss 12d and / or a reinforcing rib 12f are provided at the connection between the second part 12 and the first part 11 (i.e., at the abrupt change in the radial cross-section of the piston structure 10) to enhance the strength of the piston structure 10 and prevent stress damage to the abrupt cross-section during high-pressure impact.

[0052] Please see Figure 2The second part 12 has a piston cutter 12a formed at one end away from the first part 11. The end face of the piston cutter 12a has a convex structure to perform the action of cutting off the main circuit electrode 40. The convex structure can be a V-shape, inverted trapezoid, inverted V-shape, or triangular structure with an impact blade surface. The shape and structure of the piston cutter 12a can be determined according to requirements. Furthermore, the second part 12 also has legs 12b located at both ends of the piston cutter 12a and extending axially away from the first part 11. The legs 12b protrude from the piston cutter 12a in the axial direction away from the first part 11 so that, when applied to the pyrotechnic cutter, they can push the melt pusher 70 to move within the movable cavity 20b. The legs 12b can be one or more designs, and their specific structure can be reasonably adjusted according to actual needs. Preferably, a limiting block 12c is also provided on the side of the second part 12. When the piston structure 10 is used in a pyrotechnic cutter, the design of the limiting block 12c can restrict the piston structure 10 to move only within the stroke chamber 20a.

[0053] To effectively illustrate the role and effect of the piston structure 10 in the pyrotechnic shut-off device, this embodiment conducts a multiphysics coupled simulation analysis experiment to verify the energy harvesting efficiency and pressure release stability of the piston structure 10. The simulation experiment uses the Navier-Stokes equations as a fluid dynamics model to analyze gas flow and employs an energy loss formula to analyze the energy harvesting status.

[0054] Specifically, the Navier-Stokes equations are: In the formula, ρ is the gas density, u is the velocity vector, p is the pressure, μ is the dynamic viscosity, and F is the volume force. Its boundary conditions include an inlet peak pressure of 1~2 MPa (triggered by drive device 30), an outlet free flow (ambient pressure 0 MPa), and a piston material of PPA (polyphthalamide). The energy loss formula is... In the formula, the energy loss (ΔE) during gas flow is related to the rate of change of the cross-sectional area of ​​the flow channel (S2 / S1), where S2 is the maximum radial cross-sectional area of ​​the first part 11 and S1 is the maximum radial cross-sectional area of ​​the groove 13. This represents the flow velocity of the high-pressure gas entering the groove 13, expressed in m / s. This energy loss formula can be used to minimize ΔE through S2 / S1, while simultaneously ensuring that the gas diffusion rate matches the pressure release rate.

[0055] Furthermore, the simulation experiment was conducted using ANSYS Fluent (CFD simulation), with an unstructured mesh, a boundary layer refinement of 3 layers, and a mesh quality > 0.8. The physical models employed were the k-ε turbulence model (high-speed airflow region, velocity > 100 m / s) and the laminar flow model (low-speed region, velocity < 50 m / s). Based on the above design, the simulation experiment utilized the elliptical piston structure 10 designed in this embodiment to analyze the impact of the area ratio on performance under the same conditions through simulations of different area ratios. Specific simulation results are shown in the table below:

[0056]

[0057] As shown in the table above, when the ratio of the maximum radial cross-sectional area of ​​the first part 11 to the maximum radial cross-sectional area of ​​the groove 13 increases from 2.5:1 to 4.2:1, the energy conversion efficiency increases from 68.3% to 92.1%. Furthermore, when the ratio is 3.84:1, the energy conversion efficiency is 89.7%, the pressure release time is 13ms, and the structural stability rating is A+. Therefore, this ratio represents the optimal balance between energy conversion efficiency and stability. In addition, although energy conversion efficiency is also high (over 90%) when the ratio is greater than 3.84:1 (e.g., 4.0:1, 4.1:1, and 4.2:1), there are potential risks to structural stability at these ratios. In particular, when the ratio exceeds a critical point (e.g., above 4.0:1), the PPA material may experience creep risk under high pressure (stress > 50MPa), which could lead to a decrease in the performance of the pyrotechnic cutter or even failure. Therefore, although the energy conversion efficiency is higher at these ratios, they are not suitable as the optimal balance point due to structural stability limitations. In summary, a ratio of 3.84:1 achieves the optimal balance between energy conversion efficiency, pressure release time, and structural stability. Therefore, it is determined to be the A+ optimal balance point for pyrotechnic cut-off device design.

[0058] The data in the table above are based on ANSYS Fluent multiphysics coupling simulation, with mesh independence verification error <2% and physical model error <5%.

[0059] It should be noted that the structural stability ratings for piston structure 10 in the table are based on simulation characterization of the structure under various operating conditions. The rating criteria for this embodiment are as follows:

[0060] A- (Good Stability) indicates good structural stability in simulation experiments, but slight creep risk or deformation may exist under extreme conditions (such as when the area ratio is close to the critical point); A (Better Stability) indicates that the design exhibits excellent structural stability under various operating conditions, with creep risk and deformation within acceptable ranges; A+ (Optimal Stability) indicates that the design exhibits outstanding structural stability in simulation experiments, with extremely low creep risk and deformation, and also achieving an optimal balance in terms of energy conversion efficiency and pressure release time. This is the ideal state of the design, indicating that the design has achieved optimal solutions in multiple key performance indicators.

[0061] B- (Local stress concentration) indicates that there is a problem of local stress concentration in the design, which may increase the risk of structural damage or failure under high pressure. B (Slight deformation) indicates that the design exhibits slight deformation in simulation experiments. Although it does not affect the overall function, it may mean that the performance will be degraded in long-term use or under extreme conditions. B+ (Acceptable stability) indicates that the design exhibits acceptable structural stability overall, but may require additional monitoring and maintenance under certain specific conditions (such as high temperature, high pressure, etc.).

[0062] Meanwhile, this simulation experiment also uses a traditional circular piston to analyze the impact of the area ratio on performance by simulating different area ratios under the same conditions. The specific simulation results are shown in the table below:

[0063]

[0064] As can be seen from the above, compared with the experimental results of the elliptical piston structure (i.e., the first part of the radial cross-section is elliptical), the performance parameters of the traditional circular piston structure (i.e., the first part of the radial cross-section is circular) are generally lower. Furthermore, as the ratio increases, the performance gap between the circular and elliptical piston structures gradually widens, which verifies the expected trend in the design of this embodiment.

[0065] Example 2

[0066] Please see Figure 4 , Figure 5 This utility model embodiment also provides a fireworks cutter, which includes at least: a housing 20 with a stroke cavity 20a formed inside, a driving device 30, a main circuit electrode 40, and a piston structure 10. The specific structure and variant design of the piston structure 10 can be referred to the description in Embodiment 1, and will not be repeated here.

[0067] The housing 20 may be made of a high-strength, pressure-resistant insulating material. Preferably, the housing 20 includes an upper housing 21, a middle housing 22, a cover housing 23, and a lower housing 24 that are detachably connected in sequence. The upper housing 21 and the middle housing 22 enclose each other, forming a travel cavity 20a inside. The cover housing 23 and the lower housing 24 enclose each other, forming a movable cavity 20b and an arc-extinguishing cavity 20c inside. A sealing assembly is provided between the movable cavity 20b and the arc-extinguishing cavity 20c. Preferably, the upper housing 21 and the middle housing 22, the middle housing 22 and the cover housing 23, and the cover housing 23 and the lower housing 24 can be aligned and fitted by corresponding limiting protrusions 40c or limiting grooves to facilitate assembly. Further, the housing 20 is provided with a reinforcing structure, which includes at least one of an inner plate 27, an inner sleeve 26, and a pressure plate 28 embedded in the housing 20. Preferably, the reinforcing structure is made of metal to enhance the strength of the housing 20 and effectively reduce the impact of high-pressure gas on the housing 20.

[0068] The axial direction of the stroke cavity 20a is consistent with the axial direction of the first part 11, and its cavity shape should be an elliptical shape adapted to the design of the first part 11. That is, if the radial cross section of the first part 11 is elliptical, then at least a portion of the radial cross section of the stroke cavity 20a is an elliptical shape adapted to the first part 11, and the sealing element 60 is provided at the contact position between the stroke cavity 20a and the first part 11 to prevent gas leakage.

[0069] Preferably, the average wall thickness of the housing 20 along the major axis of the radial section of the stroke cavity 20a is greater than the average wall thickness of the housing 20 along the minor axis of the radial section of the stroke cavity 20a. For example, if the major axis dimension W1 of the piston structure 10 is 24 mm and the minor axis dimension W2 is 16 mm, then the wall thickness of the stroke cavity 20a along the major axis of the radial section of the housing 20a can be designed to be 7 mm, and the wall thickness of the stroke cavity 20a along the minor axis of the radial section of the housing 20a can be designed to be 3 mm. Compared with the traditional circular stroke cavity 20a, this wall thickness limitation design can effectively achieve miniaturization and improve space utilization while ensuring structural strength.

[0070] In this embodiment, the use of an elliptical stroke cavity 20a in conjunction with an elliptical first part 11 and a circular groove 13 not only optimizes the flow of high-pressure gas and improves the kinetic energy conversion efficiency, but also provides additional space utilization advantages for the wall thickness design of the stroke cavity 20a. This allows for a thicker wall design within a limited space, effectively adapting to the mechanical challenges of high-pressure and high-speed working environments, and improving the durability and reliability of the structure.

[0071] The main circuit electrode 40 is inserted into the stroke cavity 20a of the housing 20, and the piston structure 10 is located in the stroke cavity 20a and on one side of the main circuit electrode 40. When the driving device 30 generates high-pressure gas, the piston structure 10 moves in the stroke cavity 20a to break the main circuit electrode 40, so that the main circuit electrode 40 forms at least one break.

[0072] In this embodiment, the preferred driving device 30 is an electric starter connected to an external circuit. When the electric starter is triggered, it generates instantaneous high-pressure gas through a chemical reaction inside. The high-pressure gas first fills the groove 13 so that the energy is concentrated in the groove 13 rather than acting directly on the entire surface, thereby driving the piston structure 10 to move at a high speed. At the same time, the gas energy can be smoothly guided by the groove 13 to the end face of the piston structure 10 facing the driving device 30. This guiding effect allows the gas energy to be more effectively converted into the kinetic energy of the piston structure 10, rather than generating turbulence or energy dissipation inside the piston. This allows the piston structure 10 to move at high speed in the stroke cavity 20a to break the main circuit electrode 40, so that the main circuit electrode 40 forms at least one break, thereby cutting off the current flow in the main circuit circuit and effectively realizing the circuit protection function.

[0073] Optionally, please refer to Figure 6 The main circuit electrode 40 is provided with at least one weak break section 40a. The driving device 30 drives the piston structure 10 to cut off the weak break section 40a of the main circuit electrode 40 to form a fracture. The structure of the weak break section 40a includes, but is not limited to, notches, through holes, and local thinning structures on the main circuit electrode 40, which are narrow-aperture designs with a reduced cross-sectional area along the width direction compared to other positions. The weak break section 40a is located on the main circuit electrode 40 within the stroke cavity 20a and is directly opposite the piston cutter 12a of the piston structure 10, so that when the piston structure 10 moves at high speed to the main circuit electrode 40, the piston cutter 12a can quickly cut off the weak break section 40a. In this embodiment, the weak break section 40a preferably includes a strip-shaped inverted V-shaped notch located in the middle and along the width direction of the main circuit electrode 40, and an elongated through hole located in the middle and along the length direction of the main circuit electrode 40. This design is more conducive to the main circuit electrode 40 bearing force, facilitating rapid cutting.

[0074] Furthermore, to effectively prevent the main circuit electrode 40 from shifting or tilting after being cut, thus affecting the overall structure, in this embodiment, the main circuit electrode 40 has a limiting structure that is limited and connected to the housing 20. The limiting structure can be at least one of one or more limiting holes 40b, limiting protrusions 40c, or limiting grooves. When the limiting structure is a limiting hole 40b, the limiting hole 40b is located inside the main circuit electrode 40, and the housing 20 extends a limiting support 22a. The limiting hole 40b of the main circuit electrode 40 is sleeved on the limiting support 22a to effectively achieve horizontal radial limiting. When the limiting structure is a limiting protrusion 40c or a limiting groove (not shown in the figure), the limiting protrusion 40c or the limiting groove is located on the side of the main circuit electrode 40. Similarly, the housing 20 has a matching limiting groove or limiting protrusion 40c located near the side of the main circuit electrode 40. The cooperation of these two structures effectively achieves horizontal radial limiting.

[0075] Optionally, the main circuit electrode 40 is provided with a sealing structure 40c on the sides of the opposite ends of the travel cavity 20a to prevent external moisture or impurities or internal air pressure from entering or leaving the opposite ends of the main circuit electrode 40 and affecting its function.

[0076] Please continue reading. Figure 5 The pyrotechnic cut-off device also includes a melt 50 connected in parallel with the main circuit electrode 40; the housing 20 also has an arc-extinguishing cavity 20c inside; at least a portion of the melt 50 is located in the arc-extinguishing cavity 20c, and the arc-extinguishing cavity 20c is filled with an arc-extinguishing medium.

[0077] Specifically, when the driving device 30 triggers the generation of high-pressure gas to move the piston structure 10 to break the main circuit electrode 40, since the melt 50 is connected in parallel with the main circuit electrode 40, the current on the main circuit electrode 40 is transferred to the melt 50 to form a new path. Under high current carrying conditions, at the moment the main circuit electrode 40 is broken, the melt 50 melts due to excessive current, thus achieving high current carrying circuit protection. Through the above design of the melt 50, the arc-extinguishing chamber 20c, and the arc-extinguishing medium, the generation of an electric arc when the main circuit electrode 40 is broken can be effectively avoided. At the same time, the electric arc generated by the melting of the melt 50 is absorbed in the arc-extinguishing chamber 20c, thereby effectively improving the breaking capacity and enhancing the performance reliability and safety of the device.

[0078] Furthermore, the pyrotechnic cutter also includes a melt pusher 70, and the housing 20 further has a movable cavity 20b communicating with the stroke cavity 20a. The melt 50 extends through the self-extinguishing arc cavity 20c into the movable cavity 20b, and the melt pusher 70 is located in the movable cavity 20b. After the piston structure 10 moves in the stroke cavity 20a to break the main circuit electrode 40, under low current conditions, the piston structure 10 continues to move to push the melt pusher 70 to move in the movable cavity 20b, thereby cutting off the melt 50.

[0079] For specific implementation details, please refer to [link / reference]. Figure 7 The melt pusher 70 includes a support 71 extending axially towards the piston structure 10 and a fixing part 72 connected to the support 71. The fixing part 72 has at least one protrusion 73 on the side facing the melt 50. The melt 50 also has a slot 50c located in the movable cavity 20b and cooperating with the protrusion 73; the protrusion 73 is sleeved in the slot 50c. That is, during assembly, the support 71 of the melt pusher 70 corresponds to the support leg 12b of the piston structure 10, so that when the piston structure 10 moves, the support leg 12b pushes against the support 71, thereby driving the melt 50 cutting structure to move, and thus realizing the cutting of the melt 50. In this embodiment, the total cross-sectional area of ​​the support leg 12b of the piston structure 10 is preferably less than or equal to the total cross-sectional area of ​​the support 71 of the melt pusher 70, preferably in a ratio of 0.9 to 1, so as to ensure that the piston accurately aligns with the melt pusher 70, thereby driving the melt pusher 70 to move. The specific working principle is as follows: when the piston structure 10 moves to the point of cutting off the main circuit electrode 40, the piston structure 10 drives the support leg 12b to continue moving, so that the support leg 12b contacts the support body 71 and thus pushes the entire melt pusher 70 to move synchronously, thereby achieving the cutting off of the melt 50. Furthermore, the slot 50c of the melt 50 is fitted onto the protrusion 73 of the melt pusher 70, thereby effectively limiting the position of the melt 50 while more effectively driving the melt pusher 70 to achieve the cutting action on the melt 50. Preferably, the side of the melt pusher 70 also has a protruding ridge 74 to effectively limit the furthest point of the melt pusher 70's movement within the movable cavity 20b.

[0080] In some embodiments, please refer to Figure 8 The melt 50 has at least one set of several melt-breaking weak sections 50a spaced apart and at least one set of several cut-off weak sections 50b spaced apart. At least one set of melt-breaking weak sections 50a is located in the arc-extinguishing cavity 20c; at least one set of cut-off weak sections 50b is located in the arc-extinguishing cavity 20c or between the arc-extinguishing cavity 20c and the movable cavity 20b.

[0081] In practical implementation, the fusing weak section 50a and the cutting weak section 50b can be narrow-diameter designs with a reduced cross-sectional area along the width direction of the melt 50, such as circular through holes, elongated through holes, notches, or locally thinned structures, compared to other locations. By designing the fusing weak section 50a and the cutting weak section 50b in the arc-extinguishing cavity 20c, the arc-extinguishing effect can be effectively achieved when the melt 50 is cut off.

[0082] Optionally, please refer to Figure 9 A slit 201b is provided between the fixed part 72 and the movable cavity 20b, and the width of the slit 201b is less than or equal to 2.5 times the thickness of the melt 50. This design effectively shortens the arc path and energy. Specifically, if the width of the slit 201b is too large, it will prolong the free path of the arc between the fracture surfaces, increasing the accumulation of arc energy and the risk of reignition. Therefore, this embodiment greatly shortens the arc path and reduces the accumulation of arc energy by limiting the width of the slit 201b, thereby reducing the risk of arc reignition.

[0083] During the melting and breaking of the molten metal 50, the generation of an electric arc is unavoidable, especially under high current and high voltage conditions. The traditional method of filling the arc-extinguishing cavity 20c with an arc-extinguishing medium still has insufficient arc-extinguishing capability. For the above issues, please refer to... Figure 10 In this embodiment, the internal structure of the arc-extinguishing cavity 20c is effectively improved to enhance the arc-extinguishing capability.

[0084] Specifically, the housing 20 has at least one isolation baffle 25 extending into the arc-extinguishing cavity 20c, which does not completely separate the arc-extinguishing cavity 20c. The design of the isolation baffle 25 not only increases the contact area between the arc and the arc-extinguishing medium, allowing the molten material 50 to bypass the isolation baffle 25 and thus extinguishing the arc more quickly, but also effectively extends and segments the arc path, effectively dividing the arc during its propagation around the isolation baffle 25, thereby further accelerating arc cooling and energy loss. Furthermore, while optimizing the spatial layout, it also helps reduce the risk of arc reignition.

[0085] The isolation barriers 25 can be symmetrically or staggered along the melting path of the melt 50. For example, in this embodiment, the isolation barriers 25 extend from the axial sidewalls (i.e., the upper and lower walls) of the self-extinguishing arc cavity 20c towards the center of the cavity. Alternatively, the isolation barriers 25 can also extend from the radial sidewalls (i.e., the left and right walls) of the self-extinguishing arc cavity 20c towards the center of the cavity. The specific positions and numbers can be reasonably set according to actual needs. For example, in low-voltage, low-current scenarios, 1 to 2 isolation barriers 25 can be set; in high-voltage, high-current scenarios, the number of isolation barriers 25 can be increased to 3 to 4. This multi-level segmentation further extends the arc path while effectively saving space.

[0086] The isolation barrier 25 is made of a material with high insulation, high temperature resistance and arc erosion resistance, and its shape includes but is not limited to strip-shaped flat plate, strip-shaped wavy, sawtooth, etc. The specific design is reasonably set according to actual needs, and this embodiment does not limit it.

[0087] Preferably, please refer to Figure 10 The arc-extinguishing cavity 20c has a first gap 20d and a second gap 20e formed on its sidewall. The end of the melt 50 extends from the first port to be connected in parallel with the main circuit electrode 40. The second gap 20e connects the arc-extinguishing cavity 20c and the movable cavity 20b. The melt 50 passes through the arc-extinguishing cavity 20c and the movable cavity 20b respectively via the second gap 20e. The isolation baffle 25 divides the arc-extinguishing cavity 20c into at least a first region 201c where the first gap 20d is located and a second region 202c where the second gap 20e is located. The first region 201c and the second region 202c are connected.

[0088] In specific implementation, the first gap 20d is used to draw out the molten material 50. The drawn-out molten material 50 can be connected in parallel with the main circuit electrode 40 via a connecting electrode, or it can be directly connected in parallel with the main circuit electrode 40. The first gap 20d is frustum-shaped. The second gap 20e is used to connect the arc-extinguishing chamber 20c and the active chamber 20b. To effectively prevent the arc from entering the active chamber 20b, in this embodiment, the second gap 20e should be adapted to the width of the molten material 50 to allow the molten material 50 to pass through and to prevent the arc-extinguishing medium from overflowing.

[0089] In this embodiment, the design of using the isolation baffle 25 to separate the area containing the first gap 20d and the area containing the second gap 20e is more conducive to the movement of the melt 50 within a limited space, extending the path of the arc during the cutting process. Simultaneously, it allows for better heat exchange between the arc and the surrounding medium as the arc propagates along the path, enabling the arc to be extinguished more quickly. Preferably, the end of the isolation baffle 25 extending into the arc-extinguishing cavity 20c is at a different horizontal height from the location of the second gap 20e, further improving the arc-extinguishing efficiency.

[0090] Further, please refer to Figure 10 , Figure 11The housing 20 also has at least one positioning post 20f extending into the arc-extinguishing cavity 20c. The positioning post 20f is located on the side of the melt pusher 70 and in the arc-extinguishing cavity 20c. In this case, a set of positioning posts 20f is provided on each side. The melt 50 has at least one set of several spaced-apart cutting weak sections 50b, and at least one set of cutting weak sections 50b is located in the arc-extinguishing cavity 20c. The cutting weak section 50b includes a positioning through hole, which is sleeved on the positioning post 20f. The side wall of the positioning through hole away from the melt pusher 70 abuts against the positioning post 20f, thereby ensuring that the fracture of the melt 50 is formed in the arc-extinguishing cavity 20c outside the active cavity 20b. The positioning post 20f has a conical columnar structure, and the positioning through hole is elongated.

[0091] In this embodiment, the cooperation between the positioning post 20f of the housing 20 and the positioning through hole of the melt 50 ensures that the melt is cut at a predetermined position, namely at the positioning through hole, thus improving the accuracy and stability of the cut. Specifically, the melt pusher 70, driven by the piston structure 10, moves the melt 50 within the movable cavity 20b. As the melt 50 moves downwards, the positioning post 20f located at the positioning through hole 50b applies a force in the opposite direction to the melt 50 until the melt 50 is broken, ultimately cutting off the current at the positioning through hole.

[0092] In specific implementation, this embodiment preferably uses an elongated slotted hole as the positioning through hole, and a positioning post 20f with a conical column structure is disposed at one end of the elongated slotted hole. This arrangement results in a relatively large contact area between the positioning post 20f and the positioning through hole, which helps to disperse the stress generated during the cutting process, prevents displacement or deformation of the melt 50 due to stress concentration during the cutting impact, and improves the stability and accuracy of the cutting process.

[0093] Meanwhile, the positioning post 20f of the conical column structure has a gradually changing shape along its axis, and its cross-section is adapted to the positioning through hole. This can better guide the melt 50 into the predetermined position and achieve precise positioning. Moreover, its stable support can prevent the melt 50 from shaking or shifting before cutting. In addition, it helps to maintain the stable combustion of the electric arc during the cutting process, accelerates the cooling of the electric arc and energy dissipation, thereby improving the cutting effect.

[0094] In an alternative implementation, please continue reading. Figure 8 The cross-sectional area of ​​the narrow path between adjacent weak fusion segments 50a along the width direction is smaller than the cross-sectional area of ​​the narrow path between adjacent weak severance segments 50b along the width direction.

[0095] This design allows the weak section 50a of the melt 50 to be accelerated and automatically melted under the action of current, while the weak section 50b of the melt 50 is pulled apart under the action of the melt pusher 70 and the positioning post 20f, effectively realizing a multi-stage disconnection mechanism and improving the high breaking capacity of the pyrotechnic cutter.

[0096] In another alternative implementation, please refer to [link / reference needed]. Figure 8 The weak section 50a includes a plurality of first pre-melting through holes 501a near the end of the partition stop and a plurality of second pre-melting through holes 502a away from the end of the partition stop. The transverse cross-sectional area of ​​the narrow diameter between adjacent first pre-melting through holes 501a is smaller than that between adjacent second pre-melting through holes 502a, and the number of first pre-melting through holes 501a is greater than the number of second pre-melting through holes 502a. Because the first pre-melting through holes 501a have a small transverse cross-sectional area, high current density, large heat generation, and fast heat accumulation, their melting speed is fast, and they are more easily melted preferentially. That is, the first pre-melting through holes 501a near the partition stop are melted preferentially compared to the second pre-melting through holes 502a away from the partition stop. The disconnection time difference can be designed by adjusting the number and / or width of the narrow apertures, so that the arc is preferentially segmented under the action of the isolation barrier, achieving multi-stage arc extinguishing and further accelerating the extinction of the arc.

[0097] For better results, please continue reading. Figure 8 An external protrusion 501b is provided at the edge of the positioning through hole. The narrow diameter of the external protrusion 501b is the smallest compared to other locations of the positioning through hole, resulting in more concentrated stress and making it easier to break. By setting the external protrusion 501b, the location of the mechanical fracture can be more accurately determined, further ensuring that the fracture forms in the arc-extinguishing cavity 20c outside the movable cavity 20b, thus ensuring the arc-extinguishing effect.

[0098] Preferably, the linear movement distance of the melt pusher 70 within the movable cavity 20b is greater than or equal to 3.0 mm. This limitation effectively ensures that when the positioning through hole is broken by the melt pusher 70, its breakage position is located within the arc extinguishing cavity 20c.

[0099] In one implementation, please refer to Figure 12 The bottom of the movable cavity 12b is provided with a limiting part 201c, and the bottom sides of the melt pusher 70 are provided with protruding ribs 74, which overlap the limiting part 201c. Through the design of the protruding ribs 74 and the limiting part 201c, the movement distance of the melt pusher 70 can be effectively limited, and the fracture surface of the melt 50 after being pulled apart can be further controlled to be in the arc extinguishing cavity 20c, so as to avoid the melt pusher 70 causing excessive displacement of the melt 50 and thus failing to ensure that the fracture surface is accurately located in the arc extinguishing cavity 20c.

[0100] It should be noted that, based on the above concept, and depending on the actual needs of the pyrotechnic cutter, those skilled in the art may also add other internal components to the pyrotechnic cutter, all of which fall within the protection scope of this utility model.

[0101] In summary, the piston structure and pyrotechnic cutter provided by this utility model, through the specific structural and parameter limitations of the piston structure and the design of the specific structure of the pyrotechnic cutter, not only improve the breaking capacity and response speed of the pyrotechnic cutter, but also effectively enhance the reliability, safety and service life of the pyrotechnics, and have good application prospects.

[0102] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of this utility model can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0103] Although this document frequently uses terms such as piston structure, first part, second part, groove, piston cutter, housing, upper shell, middle shell, lower shell, drive device, main circuit electrode, melt, seal, and melt pusher, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any additional limitation would contradict the spirit of this utility model. The terms "first," "second," etc. (if present), in the description, claims, and accompanying drawings of the embodiments of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A piston structure, characterized in that: It includes a first part and a second part connected to the first part. The first part is a columnar structure extending along the axial direction and has an elliptical radial cross-sectional shape. The first part has a groove on its end face away from the second part for receiving gas impact, and the axial extension direction of the groove is consistent with the axial direction of the first part; the radial cross-sectional shape of the groove is circular.

2. The piston structure according to claim 1, characterized in that: The ratio of the major axis dimension W1 of the first part to the minor axis dimension W2 of the first part is between 1.2:1 and 1.8:1; the ratio of the axial depth d1 of the groove to the axial height d2 of the first part is between 1 / 3 and 1 / 2.

3. The piston structure according to claim 1, characterized in that: The ratio of the maximum radial cross-sectional area of ​​the first part to the maximum radial cross-sectional area of ​​the groove is between 3.5 and 4.0, or the ratio of the maximum radial cross-sectional area of ​​the first part to the maximum radial cross-sectional area of ​​the groove is 3.84:

1.

4. The piston structure according to claim 1, characterized in that: The second part has a piston cutter formed at the end away from the first part, and the end face of the piston cutter has a convex structure.

5. The piston structure according to claim 1, characterized in that: The second part is axially connected to the first part; the second part extends along the radial major axis of the first part to form a strip structure, and the width along the radial minor axis of the first part is smaller than the major axis dimension of the first part; a boss and / or reinforcing ribs are provided at the connection between the second part and the first part.

6. The piston structure according to claim 1, characterized in that: The radial cross-sectional diameter of the groove varies with the depth of the groove.

7. A fireworks cut-off device, characterized in that, include: The device includes a housing with an internal stroke cavity, a drive unit, main circuit electrodes, and a piston structure as described in any one of claims 1-6. The main circuit electrode is inserted into the stroke cavity of the housing, and the piston structure is located in the stroke cavity and on one side of the main circuit electrode; one end of the driving device is placed in the groove, and when the driving device generates high-pressure gas, the piston structure moves in the stroke cavity to break the main circuit electrode, so that the main circuit electrode forms at least one break.

8. The smoke cutter according to claim 7, characterized in that: At least a portion of the radial cross-sectional shape of the travel cavity is an ellipse adapted to the first portion, and the average wall thickness of the housing along the major axis of the radial cross-section of the travel cavity is greater than the average wall thickness of the housing along the minor axis of the radial cross-section of the travel cavity.

9. The fireworks cutter according to claim 7, characterized in that: It also includes a melt connected in parallel with the main circuit electrode; the housing also has an arc-extinguishing cavity; at least a portion of the melt is located in the arc-extinguishing cavity, which is filled with an arc-extinguishing medium.

10. The smoke cutter according to claim 9, characterized in that: It also includes a melt pusher, and the housing further has a movable cavity communicating with the stroke cavity, the melt self-extinguishing arc cavity extending through the movable cavity, and the melt pusher located in the movable cavity; After the piston structure moves within the stroke chamber to break the main circuit electrode, the piston structure continues to move to push the melt pusher within the active chamber, thereby cutting off the melt.

Images