Anti-interference fuse with electromagnetic shielding function

Abstract

The invention discloses an anti-interference fuse with an electromagnetic shielding function, and relates to the technical field of circuit protection equipment, the anti-interference fuse comprises a shielding shell assembly, an insulation isolation assembly and a melt cavity structure, the shielding shell assembly comprises a stainless steel tube and end covers screwed at the two ends of the stainless steel tube, the insulation isolation assembly comprises an annular insulation support arranged in the stainless steel pipe, the annular insulation support is connected with a shielding structure, and the shielding structure is electrically connected with any end cover. An external shielding layer is formed through the stainless steel pipe and the end covers at the two ends, the stainless steel pipe blocks external interference and external high-frequency electromagnetic interference through the metal shielding effect, a middle shielding layer is formed through the insulating isolation assembly and the annular insulating support, and a low-resistance grounding path is formed through the insulating isolation assembly and the shell grounding terminal. Residual interference passing through a gap of the stainless steel tube is attenuated, electromagnetic coupling of the stainless steel tube and the melt cavity structure is inhibited, and the problem that a traditional fuse is prone to misoperation due to electromagnetic interference is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit protection devices, and particularly to an anti-interference fuse with electromagnetic shielding function. Background Art

[0002] In the fields of modern industrial control, power electronic devices, aerospace, and new energy systems, the reliability and electromagnetic compatibility (EMC) of circuit protection devices have become core technical indicators. As a key component for overcurrent protection, the performance of fuses directly affects the safety and stability of the system. However, with the wide application of high-frequency switching power supplies, high-speed digital circuits, and wireless communication technologies, there is a large amount of electromagnetic interference (EMI) in the 10 kHz - 1 GHz frequency band in the circuit environment, including conducted interference and radiated interference, mainly from frequency converters, relays, radio frequency devices, and power grid harmonics.

[0003] The shielding design of existing fuses is mostly a single-layer metal shell or a plastic insulating housing, which can only resist low-frequency magnetic field interference (<10 kHz), and lacks effective protection against high-frequency electromagnetic pulses (such as electrostatic discharge, lightning surge) and broadband radiated interference. When the external electromagnetic interference intensity exceeds 50 V / m, an abnormal current (≥100 mA) is easily induced in the fuse element circuit, resulting in mis-fusing of the fuse or drift of the breaking characteristics. For example, in the control circuit of an industrial robot, the 10 - 100 MHz harmonic interference generated by the frequency converter can cause the action threshold deviation of a traditional fuse to exceed ±15%, leading to system shutdown failures.

[0004] When the fuse breaks the overload current, the arc generated by the vaporization of the fuse element (the temperature can reach above 3000 °C) will generate high-frequency electromagnetic radiation of 10 - 100 MHz, and the radiation intensity increases exponentially with the increase of the breaking current (when breaking a 10 kA current, the radiation field strength at 10 cm can reach 100 dBμV / m). This self-generated electromagnetic noise can cause signal distortion to precision components such as surrounding sensors and microcontrollers. Especially in a high-density integrated circuit board (PCB), the crosstalk generated by the breaking of adjacent fuses may cause the signal-to-noise ratio of the AD converter to drop by more than 20 dB, seriously affecting the control accuracy of the device. In view of this, the present invention is specifically proposed to solve the above technical problems. Summary of the Invention

[0005] The object of the present invention is to provide an anti-interference fuse with electromagnetic shielding function to solve the technical problem that the existing fuses lack effective protection against high-frequency electromagnetic pulses and broadband radiated interference.

[0006] The object of the present invention is to provide an anti-interference fuse with electromagnetic shielding function, including: Shielding housing assembly, the shielding housing assembly includes a stainless steel tube and end caps screwed to both ends of the stainless steel tube; Insulating isolation assembly, the insulating isolation assembly includes an annular insulating bracket disposed inside the stainless steel tube, a shielding structure is connected to the annular insulating bracket, and the shielding structure is electrically connected to any one of the end caps to form a low-impedance loop; Melt cavity structure, the melt cavity structure includes a ceramic insulating tube disposed inside the annular insulating bracket, electrode terminals are threadedly connected to both ends of the ceramic insulating tube, and the electrode terminals are used to connect to an external circuit so that a melting cavity is formed inside the ceramic insulating tube, and a fusing assembly is disposed in the melting cavity.

[0007] Further, a plurality of axial grooves are uniformly formed in the outer circumferential direction of the annular insulating bracket, and the axial grooves are formed along the thickness direction of the annular insulating bracket; The shielding structure includes spiral conductive bands disposed in each axial groove, and the spiral conductive bands are parallel to the length direction of the axial groove; A grounding terminal is disposed outside any one of the end caps, and a plurality of spiral conductive bands are electrically connected to the grounding terminal through wires.

[0008] Further, a central through hole is formed through the center of the end cap, an insulating sleeve is disposed inside the central through hole, the insulating sleeve is sleeved on the corresponding electrode terminal, and the electrode terminal penetrates out of the insulating sleeve.

[0009] Further, the outer peripheral wall of the stainless steel tube is nickel-plated.

[0010] Further, a plurality of screws connected by threads are uniformly disposed on the end face of the end cap, and one end of the screw away from the end cap is threadedly connected to the stainless steel tube; The screwed joint between the end cap and the stainless steel tube is sealed with an O-ring.

[0011] Further, the outer peripheral wall of the annular insulating bracket is in interference fit with the inner wall of the stainless steel tube, and the annular insulating bracket is located at the middle position of the stainless steel tube.

[0012] Further, the fusing assembly includes a flat belt disposed inside the ceramic insulating tube, and three fusing strips are uniformly welded on the flat belt; Copper pins are disposed at both ends of the flat belt, conductive holes are formed at one end of the electrode terminal close to the copper pins, and one end of the copper pin close to the electrode terminal is welded in the conductive hole.

[0013] Furthermore, a magnetic shielding ring is sleeved on the copper pin, and one side of the magnetic shielding ring away from the flat belt is adhered to the inside of the electrode terminal by high-temperature glue.

[0014] By adopting the above technical solutions, the present invention has the following beneficial effects: 1. Through the stainless steel tube and the end covers at both ends, a closed cavity is formed inside the stainless steel tube, forming an external shielding layer. The stainless steel tube blocks external interference and external high-frequency electromagnetic interference through the metal shielding effect, and at the same time provides mechanical protection for the insulation isolation components and the melt chamber structure.

[0015] 2. The insulating isolation component and the annular insulating bracket are set to form an intermediate shielding layer. The insulating isolation component and the shell grounding terminal form a low-resistance grounding path, which attenuates the residual interference passing through the gap of the stainless steel pipe and suppresses the electromagnetic coupling between the stainless steel pipe and the melt cavity structure, thus solving the problem that traditional fuses are susceptible to false operation due to electromagnetic interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are part of this application and are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings: Figure 1 A schematic diagram of the structure of an anti-interference fuse with electromagnetic shielding function provided in an embodiment of the present application; Figure 2 A schematic diagram of the structure of the anti-interference fuse with electromagnetic shielding function provided in an embodiment of the present application without the stainless steel tube; Figure 3 A schematic structural diagram of a fuse assembly of an anti-interference fuse with electromagnetic shielding function provided in an embodiment of the present application.

[0017] Figure numerals: 1. stainless steel tube; 2. end cap; 3. annular insulating bracket; 4. spiral conductive tape; 5. grounding terminal; 6. wire; 7. ceramic insulating tube; 8. electrode terminal; 9. flat tape; 10. fuse bar; 11. copper pin; 12. magnetic shielding ring; 13. insulating sleeve; 14. screw.

[0018] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0019] The specific implementation modes of the present invention are further described in detail with reference to the accompanying drawings.

[0020] See also Figures 1 to 3As shown, an embodiment of the present application provides an anti-interference fuse with electromagnetic shielding function, including: a shielding shell assembly, an insulating isolation assembly and a melt chamber structure, the shielding shell assembly includes a stainless steel tube 1 and end caps 2 screwed on both ends of the stainless steel tube 1, the insulating isolation assembly includes an annular insulating bracket 3 arranged inside the stainless steel tube 1, a shielding structure is connected to the annular insulating bracket 3, the shielding structure is electrically connected to any end cap 2 to form a low-impedance circuit, the melt chamber structure includes a ceramic insulating tube 7 arranged on the inner side of the annular insulating bracket 3, both ends of the ceramic insulating tube 7 are threadedly connected with electrode terminals 8, the electrode terminals 8 are used to connect to an external circuit so that a fuse chamber is formed inside the ceramic insulating tube 7, and a fuse assembly is arranged in the fuse chamber.

[0021] It should be noted that the fuse cavity is filled with nitrogen, which shortens the arc duration to less than 5ms. Combined with the high temperature resistance of the ceramic shell (≥300°C), the breaking capacity is increased to 10kA. The outer surface of the ceramic insulating tube 7 is coated with 300°C insulating paint to form an independent arc extinguishing cavity. The inert gas inhibits arc generation, and the ceramic material provides high temperature insulation. The electrode terminal 8 is a cylindrical structure made of oxygen-free copper.

[0022] In the above scheme, a closed cavity is formed inside the stainless steel tube 1 by the arrangement of the stainless steel tube 1 and the end covers 2 at both ends, forming an external shielding layer. The stainless steel tube 1 blocks external 10kHz-1GHz interference and external high-frequency electromagnetic interference through the metal shielding effect, and provides mechanical protection for the insulating isolation component and the melt chamber structure. A 360° grounding ring is formed by the arranged insulating isolation component and the annular insulating bracket 3 to constitute an intermediate shielding layer. The insulating isolation component and the shell grounding terminal form a low-resistance grounding path, which attenuates the residual interference passing through the gap of the stainless steel tube 1 and suppresses the electromagnetic coupling between the stainless steel tube 1 and the melt chamber structure, thereby solving the problem that the traditional fuse is susceptible to false operation due to electromagnetic interference.

[0023] In some possible implementations, see Figure 2 As shown, three axial grooves are evenly opened in the outer circumferential direction of the annular insulating support 3, and the axial grooves are opened along the thickness direction of the annular insulating support 3. The shielding structure includes a spiral conductive belt 4 arranged in each axial groove, and the spiral conductive belt 4 is parallel to the length direction of the axial groove. A grounding terminal 5 is arranged on the outside of any end cover 2, and multiple spiral conductive belts 4 are electrically connected to the grounding terminal 5 through a wire 6.

[0024] In the above scheme, when external interference enters the interior through material defects of the stainless steel tube 1 or coupling of the screw holes of the end cover 2, the spiral conductive belt 4 can quickly conduct the induced current into the earth in a skin effect manner (current density distribution along the axial groove is >80%), and attenuate the residual interference signal (attenuation ≥30dB), especially having a significant inhibitory effect on 10-100MHz common mode interference, solving the electromagnetic coupling problem between the traditional fuse housing and the melt cavity.

[0025] In some possible implementations, see Figure 1 and Figure 2 As shown, a central through hole is opened through the center of the end cover 2, an insulating sleeve 13 is arranged inside the central through hole, the insulating sleeve 13 is sleeved on the corresponding electrode terminal 8, and the electrode terminal 8 passes through the insulating sleeve 13, and the surface of the electrode terminal 8 is silver-plated to reduce the contact temperature rise (≤50K) and avoid fuse failure due to poor contact.

[0026] The outer wall of the stainless steel tube 1 is nickel-plated. After nickel plating, the equivalent conductivity of the surface of the stainless steel tube 1 is improved. In the 1GHz high frequency band, the skin depth is about 6.6μm, and the thickness of the nickel plating layer is 5-8μm, which completely covers the skin effect penetration range, so that the high-frequency current 10kHz-1GHz interference signal is mainly transmitted on the surface of the nickel layer, reducing the resistance loss of the stainless steel matrix, thereby enhancing the reflection loss and absorption loss of the stainless steel tube 1 to high-frequency radiation interference. At the same time, after nickel plating, a continuous conductive surface is formed on the surface of the stainless steel tube 1, eliminating electromagnetic scattering and gap leakage caused by surface unevenness.

[0027] In some possible implementations, see Figure 1 As shown, the end surface of the end cap 2 is evenly provided with a plurality of screws 14 connected by threads. The end of the screw 14 facing away from the end cap 2 is threadedly connected to the stainless steel pipe 1. The threaded connection between the end cap 2 and the stainless steel pipe 1 is sealed with an O-ring to achieve electrical insulation. The O-ring achieves IP65 waterproof and high air tightness (leakage rate ≤1×10⁻ 9 mbar・L / s), suitable for humid and dusty environments.

[0028] In some possible implementations, see Figure 2 As shown, the outer wall of the annular insulating support 3 is interference fit with the inner wall of the stainless steel tube 1, and the annular insulating support 3 is located in the middle of the stainless steel tube 1, which improves the assembly efficiency by 30%, supports rapid replacement of the melt chamber components, and reduces maintenance costs.

[0029] In some possible implementations, see Figure 3As shown, the fusing component includes a flat strip 9 disposed inside a ceramic insulating tube 7. Three fusing bars 10 are evenly welded onto the flat strip 9. Copper pins 11 are provided at both ends of the flat strip 9. A conductive hole is formed at one end of the electrode terminal 8 close to the copper pin 11. One end of the copper pin 11 close to the electrode terminal 8 is welded into the conductive hole, achieving rapid fusing under overload and reducing the arc energy at the fusing point.

[0030] In the above solution, the flat strip 9 is a silver alloy flat strip, the fusing bars 10 are nickel-chromium alloy fusing bars, and the diameter of the copper pin 11 is larger than the thickness of the flat strip 9, achieving rapid fusing under overload and reducing the arc energy at the fusing point. When the circuit is overloaded, the nickel-chromium alloy fusing bars 10 of the fusing component fuse first, causing the flat strip 9 to break quickly. The nitrogen gas inside the ceramic insulating tube 7 inhibits the expansion of the arc. The electrode terminal 8 ensures reliable transmission of the breaking signal through a low-resistance connection. At the same time, the ceramic insulating tube 7 prevents external contaminants from entering and affecting the performance of the melt cavity structure.

[0031] When the overload current passes through, the fusing bars 10 melt prior to the main body due to the resistance heating effect, forming an initial break point in the middle of the flat strip 9, which causes the flat strip 9 to neck and break quickly. This design makes the arc energy concentrated in the fusing point area, and the arc radiation intensity is reduced by 40% compared with the traditional melt with a uniform cross-section. The ceramic insulating tube 7 is filled with 80 kPa of nitrogen gas. When the arc is generated, the collision frequency between nitrogen molecules and the plasma increases significantly, accelerating the recombination of charged particles, reducing the arc voltage from 800 V in the traditional air environment to below 450 V, and shortening the arc duration from 10 ms to within 5 ms. At the same time, the ceramic insulating tube 7 quickly conducts out the arc energy through radial heat dissipation, avoiding cracking of the housing caused by local overheating.

[0032] In some possible implementation embodiments, as shown in Figure 3 As shown, a magnetic shielding ring 12 is sleeved on the copper pin 11. One side of the magnetic shielding ring 12 facing away from the flat strip 9 is pasted to the inner side of the electrode terminal 8 with high-temperature glue. The magnetic shielding ring 12 absorbs the high-frequency magnetic radiation generated when the fusing bars 10 fuse. By utilizing the complex characteristics of its high-frequency magnetic permeability, the magnetic shielding ring 12 converts the circular magnetic field generated when the flat strip 9 breaks into magnetic hysteresis loss, reducing the radiation field strength at 10 cm from 100 dBμV / m to below 70 dBμV / m. The close layout of the magnetic shielding ring 12 and the flat strip 9 realizes efficient absorption of near-field radiation.

[0033] This specific embodiment is only an explanation of the invention and is not a limitation of the invention. Those skilled in the art can make modifications without creative contributions to this embodiment according to their needs after reading this specification, but as long as they are within the protection scope of the invention, they are protected by the patent law.

Claims

1. An anti-interference fuse with electromagnetic shielding function, characterized in that, include: A shielding shell assembly, the shielding shell assembly comprising a stainless steel tube (1) and end caps (2) screwed to both ends of the stainless steel tube (1); An insulating isolation component, the insulating isolation component comprising an annular insulating support (3) arranged inside the stainless steel pipe (1), a shielding structure connected to the annular insulating support (3), the shielding structure being electrically connected to any of the end covers (2) to form a low impedance circuit; A melt chamber structure, the melt chamber structure comprising a ceramic insulating tube (7) arranged inside the annular insulating support (3), both ends of the ceramic insulating tube (7) being threadedly connected with electrode terminals (8), the electrode terminals (8) being used to connect to an external circuit, so that a fuse chamber is formed inside the ceramic insulating tube (7), and a fuse assembly is arranged in the fuse chamber.

2. The anti-interference fuse with electromagnetic shielding function according to claim 1, characterized in that The annular insulating support (3) is evenly provided with three axial grooves in the outer circumferential direction, and the axial grooves are provided along the thickness direction of the annular insulating support (3); The shielding structure comprises a spiral conductive strip (4) arranged in each of the axial slots, wherein the spiral conductive strip (4) is parallel to the length direction of the axial slot; A grounding terminal (5) is provided outside any of the end covers (2), and the plurality of spiral conductive strips (4) are electrically connected to the grounding terminal (5) via a wire (6).

3. The anti-interference fuse with electromagnetic shielding function according to claim 2, wherein A central through hole is formed through the center of the end cover (2), an insulating sleeve (13) is arranged inside the central through hole, the insulating sleeve (13) is sleeved on the corresponding electrode terminal (8), and the electrode terminal (8) passes through the insulating sleeve (13).

4. The anti-interference fuse with electromagnetic shielding function according to claim 3, characterized in that, The outer peripheral wall of the stainless steel tube (1) is nickel-plated.

5. The anti-interference fuse with electromagnetic shielding function according to claim 4, characterized in that, The end surface of the end cover (2) is evenly provided with a plurality of threaded screws (14), and the ends of the screws (14) facing away from the end cover (2) are threadedly connected to the stainless steel pipe (1); The threaded connection between the end cover (2) and the stainless steel tube (1) is sealed with an O-ring.

6. The anti-interference fuse with electromagnetic shielding function according to claim 5, characterized in that, The outer peripheral wall of the annular insulating support (3) is interference-fitted with the inner wall of the stainless steel pipe (1), and the annular insulating support (3) is located in the middle of the stainless steel pipe (1).

7. The anti-interference fuse with electromagnetic shielding function according to claim 6, characterized in that, The fuse assembly comprises a flat strip (9) arranged inside the ceramic insulating tube (7), and three sections of fuse strips (10) are uniformly welded on the flat strip (9); Copper pins (11) are provided at both ends of the flat strip (9), a conductive hole is provided at one end of the electrode terminal (8) close to the copper pin (11), and one end of the copper pin (11) close to the electrode terminal (8) is welded in the conductive hole.

8. The anti-interference fuse with electromagnetic shielding function according to claim 7, characterized in that, A magnetic shielding ring (12) is sleeved on the copper pin (11), and the side of the magnetic shielding ring (12) facing away from the flat belt (9) is adhered to the inner side of the electrode terminal (8) by means of high-temperature glue.

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