Excitation fuse

Abstract

The application discloses an excitation fuse which can reduce product appearance layers and improve product strength when separating an arc passage shell and an arc extinguishing chamber shell. The excitation fuse comprises a top cover, an upper shell, a lower shell, a middle shell, a gas generating device, a piston and a conductor. The top cover, the upper shell and the lower shell are sequentially connected from top to bottom through screw locking, buckle connection and the like, the conductor is clamped between the upper shell and the lower shell and is kept relatively fixed with the upper shell and the lower shell. The lower surface of the upper shell is concavely provided with a movable cavity, the piston is movably fitted in the movable cavity, and the gas generating device is arranged at the top of the movable cavity. The upper surface of the lower shell is concavely provided with a mounting cavity, the bottom of the mounting cavity is concavely provided with an arc extinguishing cavity, and the middle shell is embedded in the mounting cavity. The upper surface of the middle shell is flush with the upper surface of the lower shell and is provided with a guide channel penetrating to the lower surface of the middle shell. The upper surface of the lower shell is further provided with a blocking wall embedded in the upper shell for prolonging an arc path.

Description

Technical Field

[0001] This invention belongs to the field of power control and circuit protection technology, and specifically refers to an excitation fuse. Background Technology

[0002] An activated fuse is a fast circuit breaking protection device widely used in power control and circuit protection. An activated fuse generally consists of an upper housing, a lower housing, a gas generator, a piston, and a conductor. Its basic working principle is as follows: A cavity is provided inside the upper housing, within which the gas generator, piston, and conductor are housed. The conductor can be connected to the external circuit requiring protection. When a fault current occurs in the circuit, the gas generator receives an external excitation signal, generates and releases high-pressure gas, which drives the piston to move. The piston cuts off the conductor, thereby quickly disconnecting the circuit and protecting the circuit and equipment.

[0003] To achieve better arc extinguishing performance, some existing excitation fuses employ a technical solution where the arc channel (the gap between the middle shell and the piston) and the arc extinguishing chamber work together. In this solution, because the thickness of the piston pin is much smaller than the width of the arc extinguishing chamber, it is impossible to integrate the arc channel and the arc extinguishing chamber into the same housing component. Therefore, they need to be separated into two independent housing components—the middle shell for forming the arc channel and the lower shell for forming the arc extinguishing chamber. However, while this split structure provides good arc extinguishing performance, it also creates new problems: visually, the separation increases the overall number of layers in the product, resulting in a less compact structure and a less appealing appearance. More importantly, the height of the housing layer containing the arc channel (i.e., the middle shell) is usually relatively small, making this layer a weak point in the overall strength of the product. It is prone to breakage under high-pressure gas impact or external mechanical stress, significantly reducing the overall structural strength of the product. Therefore, how to improve the overall strength of the product without increasing the number of layers while ensuring arc extinguishing performance has become a pressing technical problem to be solved in the structural design of excitation fuses. Summary of the Invention

[0004] The main objective of this invention is to provide an excitation fuse that can effectively improve the overall structural strength of the product without increasing the overall number of layers, while separating the arc channel housing (middle shell) and the arc extinguishing chamber housing (lower shell).

[0005] To achieve the above objectives, the solution of the present invention is: An excitation fuse includes a top cover, an upper shell, a lower shell, a middle shell, a gas generator, a piston, and a conductor. The top cover, upper shell, and lower shell are connected sequentially from top to bottom by means of screws, snap-fit ​​connections, etc. The conductor is sandwiched between the upper shell and the lower shell and remains relatively fixed to the upper and lower shells. The lower surface of the upper shell has a recessed movable cavity, in which the piston is movably fitted, and the gas generator is located at the top of the movable cavity. The upper surface of the lower shell has a recessed mounting cavity, and the bottom of the mounting cavity has a recessed arc-extinguishing cavity. The middle shell is embedded in the mounting cavity. The upper surface of the middle shell is flush with the upper surface of the lower shell and has a guide channel extending to the lower surface of the middle shell. The upper surface of the lower shell also has a baffle wall embedded in the upper shell to extend the arc path.

[0006] After adopting the above technical solution, the present invention has the following technical effects: (1) By recessing the mounting cavity on the upper surface of the lower shell, the present invention can completely enclose the middle shell inside the product without showing additional layers in appearance, thereby avoiding the increase in the overall number of layers of the product due to the split structure, resulting in a more compact and beautiful appearance.

[0007] (2) The upper surface of the middle shell is flush with the upper surface of the lower shell, so that the middle shell is completely embedded in the lower shell, which overcomes the problem that the number of product appearance layers must be increased in order to separate the arc channel and the arc extinguishing chamber in the prior art.

[0008] (3) After the middle shell with relatively low strength is embedded in the mounting cavity of the lower shell, the side wall of the mounting cavity can form circumferential support for the middle shell. In actual application, even if it is subjected to the impact of high pressure gas or external mechanical stress, the middle shell is not easy to break, which significantly improves the overall structural strength of the product.

[0009] (4) The arc-extinguishing chamber recessed at the bottom of the mounting cavity is connected to the guide channel of the middle shell, which not only ensures the independent functional zoning of the arc-ignition channel and the arc-extinguishing chamber, but also realizes the compact integration of the two in terms of structure, taking into account both excellent arc-extinguishing performance and overall structural strength.

[0010] In a preferred embodiment, the lower surface of the middle shell is provided with a positioning protrusion, and the bottom of the mounting cavity is provided with a positioning groove for the positioning protrusion to be inserted. Through the interlocking of the positioning protrusion and the positioning groove, rapid and accurate positioning can be achieved when the middle shell is inserted into the mounting cavity, ensuring that the guide channel of the middle shell is precisely aligned with the arc-extinguishing cavity below.

[0011] In a preferred embodiment, the middle shell and the sidewall of the mounting cavity are fitted with a clearance fit.

[0012] In a preferred embodiment, the conductor extends along the length of the lower shell, and the upper surface of the middle shell is recessed with a groove for the conductor to pass through. The upper end of the guide channel communicates with the bottom of the groove. The upper surface of the lower shell has protruding baffles on both sides of the mounting cavity along its length. The lower surface of the upper shell has recessed grooves for the baffles to be embedded in. By protruding baffles on both sides of the mounting cavity of the lower shell and embedding them in the grooves of the upper shell, the mating surface between the upper and lower shells is increased, improving the sealing and anti-misalignment capabilities of the shell connection. Furthermore, the presence of the baffles causes the arc path to become less straight as it spreads from the conductor's fracture point to the arc-extinguishing cavity, requiring it to bypass the baffle. This effectively extends the contact path and time between the arc and the inner wall of the shell and the arc-extinguishing material, allowing for more thorough cooling and deionization of the arc, accelerating arc extinguishing, and improving the product's arc-extinguishing and breaking capabilities.

[0013] Furthermore, the surface of the baffle wall is in clearance fit with the inner wall of the groove.

[0014] Meanwhile, the distance between the ends of the baffles along the length of the lower shell is greater than the distance between the side walls of the movable cavity along the length of the lower shell. This dimensional relationship ensures that the electric arc generated from the break in the conductor must first pass through the baffles, regardless of which direction it spreads, thus avoiding the possibility of the electric arc "bypassing" the baffles and reliably extending the arc path.

[0015] In a preferred embodiment, the top of the movable cavity is recessed with a movable groove, and the gas generating device is installed within the movable groove. A circular annular wall protrudes from the upper surface of the piston. The wall is movably fitted within the movable groove, and a ring of ribs protrudes from its outer circumference. The ribs are interference-fitted with the inner wall of the movable groove. Thus, the interference-fit ribs create a sealed fit between the piston's wall and the movable groove of the upper shell. The wall and the movable groove together form a sealed chamber. After the gas generating device is activated, the high-pressure gas is confined within this sealed chamber, ensuring that the gas pressure can efficiently act on the piston, propelling it downwards rapidly. During this process, metal particles and fragments mixed in with the high-pressure gas are effectively confined within the sealed chamber, adhering to the inner wall, bottom surface, and inner wall of the movable groove, preventing them from entering the "arc space" between the piston pin and the conductor. This solution has three important effects: First, it prevents metal debris from entering the arc space, which could lead to reignition or the formation of a conductive path, thus ensuring the reliability of arc extinguishing. Second, it prevents debris from adhering to the cut surface or pin surface of the conductor, thereby reducing insulation resistance and ensuring that the insulation strength of the product meets the requirements after operation. Third, the enclosure prevents the energy generated by the gas generator from spreading outwards, instead concentrating it within the enclosure and applying it entirely to the upper part of the piston, thus improving energy utilization.

[0016] Furthermore, the piston has protruding pins on its lower surface, and the lower end of each pin has a shearing edge. The conductor has a neck opposite to the shearing edge, and the conductor at the neck is thinner, making it easier to cut. The guide channel is opposite to the pins. The cross-sectional area of ​​the neck is smaller than other parts of the conductor, effectively reducing the shearing force required for cutting, allowing the conductor to break quickly and accurately at a predetermined position. The number of pins, necks, guide channels, and arc-extinguishing chambers can be set to two sets to improve the functional stability of the product.

[0017] In a preferred embodiment, the arc-extinguishing chamber is filled with an arc-extinguishing material, including but not limited to quartz sand and glass microspheres. The arc-extinguishing material filling the arc-extinguishing chamber can strongly cool and deionize the arc after it enters the chamber, accelerating the dissipation of arc energy, shortening the arc burning time, and further improving the product's breaking capacity and arc-extinguishing performance.

[0018] In a preferred embodiment, the conductor is made of a conductive metal, such as copper or silver; the top cover, upper shell, lower shell, middle shell, and piston are all made of insulating plastics, such as polybutylene terephthalate (PBT) or polyamide (PA, nylon). Attached Figure Description

[0019] Figure 1 This is an overall perspective view of a specific embodiment of the present invention.

[0020] Figure 2 Overall explosion of a specific embodiment of the present invention Figure 1 .

[0021] Figure 3 Overall explosion of a specific embodiment of the present invention Figure 2 .

[0022] Figure 4 This is a cross-sectional view of the upper shell of a specific embodiment of the present invention.

[0023] Figure 5 This is a bottom view of the upper shell of a specific embodiment of the present invention.

[0024] Figure 6 This is a cross-sectional view of the lower shell of a specific embodiment of the present invention.

[0025] Figure 7 This is a top view of the lower shell of a specific embodiment of the present invention.

[0026] Figure 8 This is a cross-sectional view of the middle shell in a specific embodiment of the present invention.

[0027] Figure 9 This is a cross-sectional view of the piston according to a specific embodiment of the present invention.

[0028] Figure 10 This is a perspective view of the piston according to a specific embodiment of the present invention.

[0029] Figure 11 This is a cross-sectional view of a specific embodiment of the present invention in its conventional state.

[0030] Figure 12 This is a cross-sectional view of the broken state according to a specific embodiment of the present invention.

[0031] Figure 13 This is a schematic diagram of the arc path in a specific embodiment of the present invention.

[0032] Explanation of icon numbers: 1-Top cover; 2-Upper shell; 21-Moving cavity; 21a-Side wall spacing; 22-Insertion groove; 23-Moving groove; 3-Lower shell; 31-Mounting cavity; 32-Arc extinguishing cavity; 33-Positioning groove; 34-Baffle; 34a-End spacing; 4-Middle shell; 41-Positioning protrusion; 42-Guide channel; 43-Groove; 5-Gas generating device; 6-Piston; 61-Enclosure wall; 62-Rib; 63-Pin; 64-Shearing edge; 7-Conductor; 71-Neck; 8-Arc extinguishing material. Detailed Implementation

[0033] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0034] like Figures 1 to 3 As shown, this invention provides an activated fuse, comprising a top cover 1, an upper shell 2, a lower shell 3, a middle shell 4, a gas generating device 5, a piston 6, and a conductor 7. The top cover 1, upper shell 2, and lower shell 3 are connected sequentially from top to bottom, and can be detachably fixed by means of screws, snap-fit ​​connections, etc., for ease of assembly and maintenance. The conductor 7 is sandwiched between the upper shell 2 and the lower shell 3, and remains relatively fixed to them. The conductor 7 extends along the length of the lower shell 3, with both ends protruding outside the shell for connection to external circuits requiring protection; therefore, both ends of the conductor 7 can be provided with connection holes for connecting wires.

[0035] like Figure 4 and Figure 5 As shown, the lower surface of the upper shell 2 is recessed with a movable cavity 21, in which the piston 6 is movably fitted, and the piston 6 can reciprocate in the vertical direction within the movable cavity 21. The top of the movable cavity 21 is further recessed with a movable groove 23, in which a gas generating device 5 is installed. The gas generating device 5 is used to receive external excitation signals, generate and release high-pressure gas to drive the piston 6. The lower surface of the upper shell 2 is also recessed with a groove 22 for engaging with the baffle 34 on the lower shell 3.

[0036] like Figure 6 and Figure 7 As shown, the upper surface of the lower shell 3 is recessed with a mounting cavity 31, and the bottom of the mounting cavity 31 is further recessed with an arc-extinguishing cavity 32. The arc-extinguishing cavity 32 can be filled with arc-extinguishing material 8 (such as... Figure 11 , Figure 12 As shown, the arc-extinguishing material 8 can be an insulating material with cooling and deionization effects, such as quartz sand or glass microspheres, to accelerate the extinction of the electric arc. A positioning groove 33 is also recessed at the bottom of the mounting cavity 31 to cooperate with the positioning protrusion 41 on the middle shell 4, achieving accurate positioning of the middle shell 4. Baffle walls 34 protrude from both sides of the upper surface of the lower shell 3 along the length of the mounting cavity 31. The baffle walls 34 are used to extend the arc path and improve the arc-extinguishing effect.

[0037] like Figure 8 As shown, the middle shell 4 is embedded in the mounting cavity 31, and the upper surface of the middle shell 4 is flush with the upper surface of the lower shell 3. The middle shell 4 is provided with a guide channel 42 extending to the lower surface of the middle shell 4. The guide channel 42 is opposite to the pin 63 of the piston 6 and is used to guide the pin 63 to move downward and enter the arc extinguishing cavity 32. When the fuse is activated to trigger the melting function, the gap between the pin 63 and the guide channel 42 serves as the arc ignition channel. The upper surface of the middle shell 4 is also recessed with a groove 43 for the conductor 7 to pass through. The upper end of the guide channel 42 is connected to the bottom of the groove 43. The lower surface of the middle shell 4 is provided with a positioning protrusion 41. The positioning protrusion 41 is embedded in the positioning groove 33 at the bottom of the mounting cavity 31 to achieve rapid and accurate positioning between the middle shell 4 and the lower shell 3. The middle shell 4 and the side wall of the mounting cavity 31 are preferably fitted with a small clearance or a zero clearance, which facilitates assembly and allows the side wall of the mounting cavity 31 to provide good circumferential support for the middle shell 4.

[0038] like Figure 9 and Figure 10 As shown, the upper surface of the piston 6 is provided with a circular annular wall 61, which is movably fitted within the movable groove 23 of the upper shell 2. A ring of ribs 62 protrudes from the outer periphery of the wall 61, and the ribs 62 are press-fitted with the inner wall of the movable groove 23. Thus, after the piston 6 is installed into the upper shell 2 and in place, a sealed chamber is formed between the wall 61 and the movable groove 23, and the press-fit of the ribs 62 ensures the sealing of this chamber. The lower surface of the piston 6 is provided with protruding pins 63, and the lower end of the pins 63 is provided with a shearing edge 64, which is used to cut the conductor 7. The number of pins 63 can be set according to actual needs; in this embodiment, two sets are preferred to improve the functional stability of the product.

[0039] The conductor 7 is made of a conductive metal, such as copper, silver, or a copper-silver alloy, which has good electrical conductivity and mechanical strength. The conductor 7 has a neck 71 opposite to the shearing blade 64. The thickness of the conductor at the neck 71 is smaller than other parts of the conductor 7, resulting in a smaller cross-sectional area. This effectively reduces the shearing force required for cutting, allowing the conductor 7 to break quickly and accurately at the predetermined position. The top cover 1, upper shell 2, lower shell 3, middle shell 4, and piston 6 are all made of insulating plastic, such as polybutylene terephthalate (PBT) or polyamide (PA, nylon), which has good electrical insulation and mechanical strength and is easy to process using injection molding.

[0040] The working principle of this invention is as follows: (I) Figure 11 The diagram shows a cross-sectional view of the excitation fuse of the present invention in its normal state (non-operational state). In this state, the conductor 7 passes completely between the upper shell 2 and the lower shell 3. The movable cavity 21 and the arc-extinguishing cavity 32 are located above and below the conductor 7, respectively. The piston 6 is located at the upper part of the movable cavity 21. A predetermined gap is maintained between the lower end (shear blade 64) of the lead 63 and the neck 71 of the conductor 7. The conductor 7 is in a conductive state, and the circuit operates normally. The gas generating device 5 is installed inside the movable slot 23. The enclosure wall 61 and the movable slot 23 are sealed together by ribs 62, forming a closed chamber.

[0041] (II) When a fault current occurs in the circuit, the gas generator 5 receives an external excitation signal and activates, generating a large amount of high-pressure gas. Due to the interference fit between the rib 62 and the inner wall of the movable groove 23, the sealed chamber formed by the enclosure 61 and the movable groove 23 has good sealing performance. The high-pressure gas is confined within this sealed chamber and will not leak to other areas. The pressure of the high-pressure gas pushes the piston 6 to move downward rapidly. During this process, metal particles and fragments mixed in with the high-pressure gas are effectively confined inside the sealed chamber, adhering to the inner wall and bottom surface of the enclosure 61 and the inner wall of the movable groove 23, preventing them from entering the "arc space" between the pin 63 of the piston 6 and the conductor 7. This avoids the problem of metal debris entering the arc space and causing the arc to reignite or form a conductive path, and also prevents debris from adhering to the cut surface of the conductor 7 or the surface of the pin 63, thus reducing the insulation resistance and ensuring that the insulation strength of the product meets the requirements after activation.

[0042] (III) Driven by high-pressure gas, piston 6 continues to descend, pin 63 passes through the guide channel 42 of the middle shell 4, and the shearing edge 64 contacts the constricted neck 71 of the conductor 7. Because the cross-sectional area of ​​the constricted neck 71 is small, the shearing edge 64 can quickly cut the conductor 7 at the constricted neck 71 with a small shearing force, forming a physical break and thus disconnecting the circuit. Afterward, piston 6 continues to move downward until it reaches its travel limit. At this point, the lower end of pin 63 enters the arc-extinguishing cavity 32, such as... Figure 12 As shown.

[0043] (IV) At the instant the conductor 7 is cut, an electric arc will be generated at the break point. The arc will spread outward along the break point of the conductor 7 and the gaps between the components. Figure 13 As shown, since the upper surface of the lower shell 3 has protruding baffles 34 on both sides along the length of the mounting cavity 31, and the baffles 34 are embedded in the grooves 22 of the upper shell 2, when the arc spreads from the break of the conductor 7 to the arc-extinguishing cavity 32, the arc path is no longer straight, but needs to bypass the baffles 34. The end spacing 34a of the baffles 34 in the length direction is greater than the side wall spacing 21a of the movable cavity 21 in the length direction. This dimensional relationship ensures that the arc generated from the break of the conductor 7 must first pass through the baffles 34 regardless of which direction it spreads, avoiding the possibility of the arc "bypassing" the baffles 34, thus reliably extending the arc path. The extension of the arc path greatly increases the contact path and time between the arc and the inner wall of the shell and the arc-extinguishing material 8 in the arc-extinguishing cavity 32, the arc is cooled and deionized more fully, the energy is dissipated rapidly, and the arc is finally extinguished in the arc-extinguishing cavity 32.

[0044] In summary, this invention achieves the effect of separating the arc-extinguishing channel shell (middle shell 4) and the arc-extinguishing chamber shell (lower shell 3) without increasing the overall number of layers of the product by recessing the mounting cavity 31 on the upper surface of the lower shell 3 and embedding the middle shell 4 within the mounting cavity 31, making the upper surface of the middle shell 4 flush with the upper surface of the lower shell 3. At the same time, the sidewall of the mounting cavity 31 provides circumferential support for the middle shell 4, improving the overall structural strength of the product. By setting the baffle 34 to extend the arc path and by forming a sealed chamber through the interference fit between the rib 62 and the movable groove 23 to restrict metal debris from entering the arc space, the arc-extinguishing performance and insulation strength after operation of the product are effectively improved.

[0045] The above embodiments and figures are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. An activated fuse, comprising a top cover, an upper shell, a lower shell, a middle shell, a gas generating device, a piston, and a conductor; wherein the top cover, upper shell, and lower shell are connected sequentially from top to bottom, and the conductor is sandwiched between the upper shell and the lower shell; a movable cavity is recessed on the lower surface of the upper shell, the piston is movably fitted within the movable cavity, and the gas generating device is disposed at the top of the movable cavity; characterized in that: The upper surface of the lower shell is recessed with a mounting cavity, and the bottom of the mounting cavity is recessed with an arc-extinguishing cavity. The middle shell is embedded in the mounting cavity. The upper surface of the middle shell is flush with the upper surface of the lower shell and is provided with a guide channel that extends to the lower surface of the middle shell. The upper surface of the lower shell is also provided with a baffle wall embedded in the upper shell to extend the arc path.

2. The excitation fuse according to claim 1, characterized in that: The lower surface of the middle shell is provided with a positioning protrusion, and the bottom of the mounting cavity is provided with a positioning groove for the positioning protrusion to be inserted.

3. The excitation fuse according to claim 1, characterized in that: The middle shell and the side wall of the mounting cavity are fitted with a clearance fit.

4. The excitation fuse according to claim 1, characterized in that: The conductor extends along the length of the lower shell; the upper surface of the lower shell has protruding baffles on both sides of the mounting cavity along the length of the lower shell; the lower surface of the upper shell has recessed grooves for the baffles to be embedded.

5. The excitation fuse according to claim 4, characterized in that: The surface of the baffle wall is in clearance fit with the inner wall of the groove.

6. The excitation fuse according to claim 4, characterized in that: The distance between the ends of the baffles along the length of the lower shell is greater than the distance between the side walls of the movable cavity along the length of the lower shell.

7. The excitation fuse according to claim 1, characterized in that: The top of the movable cavity is recessed with a movable groove, and the gas generating device is installed in the movable groove; the upper surface of the piston is provided with a ring of surrounding wall; the surrounding wall is movably fitted in the movable groove, and its outer circumferential surface is provided with a ring of ribs, the ribs being interference fit with the inner wall of the movable groove.

8. The excitation fuse according to claim 7, characterized in that: The piston has protruding pins on its lower surface, and the lower end of the pins has a shearing edge; the conductor has a constricted neck opposite to the shearing edge; the guide channel is opposite to the pins.

9. The excitation fuse according to claim 1, characterized in that: The arc-extinguishing cavity is equipped with arc-extinguishing material.

10. The excitation fuse according to claim 1, characterized in that: The conductor is made of conductive metal; the top cover, upper shell, lower shell, middle shell and piston are all made of insulating plastic.

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