High-voltage-resistant organic temperature sensing body temperature fuse structure

Abstract

The application discloses a high-voltage-resistant organic temperature-sensitive body temperature fuse structure and relates to the technical field of temperature fuses. The structure comprises a shell, a first cable, a second cable, a conductive plate, a conductive spring, a fixing ring, a bimetallic disc spring, an organic temperature-sensitive block, an inner metal disc and a conductive column. The bimetallic disc spring is used to jump and deform at a specific temperature, thereby pushing the inner metal disc to separate the butt-jointed conductive column, so that the protection effect that the circuit is automatically disconnected at the specific temperature is realized. The organic temperature-sensitive block is annularly distributed near the conductive column, and the approximate insulation characteristic of the organic temperature-sensitive block can effectively inhibit the size of the electric arc generated in the moment of separation of the conductive column. Insulating oil is injected into the shell, so that the overall voltage resistance performance is further improved. Meanwhile, the organic matter has better heat conductivity than the metal structure, can quickly and accurately transmit the ambient temperature to the bimetallic disc spring, and makes the deformation temperature of the metal spring more accurate.

Description

Technical Field

[0001] This invention relates to the field of temperature fuse technology, and more specifically, to a high-pressure-resistant organic thermocouple temperature fuse structure. Background Technology

[0002] A thermal fuse is an overheat protection component widely used in household appliances, industrial equipment, automotive electronics, and other fields. When the equipment experiences an abnormal temperature rise and reaches a preset temperature, the thermal fuse will automatically disconnect the circuit to prevent fires or equipment damage accidents.

[0003] Existing thermal fuses are mainly divided into two types: low-melting-point alloy type and organic material temperature-sensing type. Low-melting-point alloy type thermal fuses rely on the melting of a low-melting-point alloy at a specific temperature to break the circuit, but they suffer from problems such as large arcing, poor voltage withstand capability, and low operating temperature accuracy. Organic material temperature-sensing type thermal fuses utilize the melting or softening of organic materials at a specific temperature to release spring tension and break the circuit. Although the operating temperature accuracy is improved, the following drawbacks still exist: Insufficient withstand voltage performance makes it prone to insulation breakdown under high voltage conditions, failing to meet the protection requirements of high voltage electrical equipment; Large electric arcs can easily be generated when conductive components are separated, leading to contact erosion and affecting service life and reliability; The temperature sensor has poor thermal conductivity, and there is a lag in temperature transfer, which leads to inaccurate deformation temperature of the bimetallic spring and large operating error. The overall structure is complex, assembly is difficult, and production costs are high.

[0004] Furthermore, existing organic-based temperature-sensing fuses still face numerous bottlenecks in mass production and long-term reliability: high-precision operating temperature settings are difficult to mass-produce; high-coaxiality structures have low assembly yields; and the long-term sealing performance of insulating oil is difficult to withstand wide-temperature environments. The nominal long cycle life is difficult to implement under load conditions; the conductivity reliability of the center contact is insufficient; and peripheral heating and spring self-heating can easily interfere with operating accuracy. Simultaneously, the arc-extinguishing effect of the organic temperature-sensing block is limited; the lack of compensation space for thermal expansion of the insulating oil can easily lead to sealing failure; and the insufficient matching between the spring preload and the spring's jump and reset characteristics can easily cause operating temperature deviation and reset jamming problems, thus restricting the large-scale application and long-term service stability of the product.

[0005] Therefore, there is an urgent need for an organic material temperature-sensing fuse structure with high pressure resistance, high precision, and good arc suppression effect to solve the above problems. Summary of the Invention

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A high-pressure resistant organic thermoelectric fuse structure includes a housing, with a first cable and a second cable respectively sealed and connected to both ends of the housing; a conductive plate is fixedly disposed inside the housing near one end of the first cable, and the conductive plate is electrically connected to the first cable; a conductive spring, a retaining ring, a bimetallic disc spring, an organic thermoelectric block, an inner metal disc, and a conductive post are arranged coaxially on the right side of the conductive plate in sequence. The left end of the conductive spring is fixedly connected to the conductive plate, and the right end of the conductive spring is in contact with the center of the left side of the bimetallic disc spring. The fixing ring is fixedly installed on the inner wall of the outer shell, and its inner ring edge supports the outer periphery of the bimetallic disc spring. The organic temperature sensing block has a ring-shaped structure and is coaxially sleeved on the outside of the conductive post, and the left side of the organic temperature sensing block is in contact with the outer periphery of the right side of the bimetallic disc spring. The inner metal disc is disposed between the bimetallic disc spring and the conductive post, and is in contact with the center of the right side of the bimetallic disc spring. The right end of the conductive post is electrically connected to the second cable. The internal cavity of the outer shell is filled with insulating oil, the filling amount is 85% of the cavity volume, and a gas phase space is reserved at the top of the cavity to compensate for the thermal expansion of the insulating oil.

[0007] As a further improvement to the above technical solution, the bimetallic disc spring is composed of an active layer and a passive layer. The active layer is a manganese-nickel-copper alloy, and the passive layer is an iron-nickel alloy. The thickness ratio of the two layers is 1:(0.9-1.1). The bimetallic disc spring has the characteristic that the convex surface faces the conductive spring at room temperature, and when the preset operating temperature is reached, it suddenly jumps and flips to face the conductive post. Its sudden jump displacement is 0.6-1.0 mm, and the sudden jump response time is less than 10 ms.

[0008] As a further improvement to the above technical solution, the bimetallic disc spring undergoes a shaping heat treatment at 320-380℃ for 1.5-2.5 hours, with the temperature deviation of a single batch controlled within ±3℃. After temperature grading and screening of finished products, the temperature deviation of high-precision gears can reach ±1℃. The reset temperature is 40-50℃ lower than the operating temperature.

[0009] As a further improvement to the above technical solution, the bimetallic disc spring is made of a high thermal conductivity homogeneous bimetallic alloy material, with uniform radial thermal conductivity and an overall radial temperature difference of less than 0.5℃. The optimized composition ratio of the bimetallic alloy improves conductivity, and the self-heating temperature rise of the spring under rated operating current is less than 0.8℃, so the influence of self-heating on the operating temperature error is controllable.

[0010] As a further improvement to the above technical solution, the organic temperature sensing block is made of thermosetting epoxy resin or phenolic resin-based composite material with added alumina, aluminum nitride or silicon carbide thermally conductive fillers. The mass fraction of the thermally conductive filler is 30%-50%, its thermal conductivity is not less than 0.8W / (m·K), its breakdown voltage is not less than 20kV / mm, and its operating temperature range is -40℃ to 180℃.

[0011] As a further improvement to the above technical solution, the organic temperature sensing block is modified to withstand electric arcs, and gas-generating arc-extinguishing filler is added to the inner wall of its inner ring. Under the action of electric arc, the filler decomposes instantaneously to generate a gas blowing effect, which works in conjunction with the insulating oil to extinguish the arc.

[0012] As a further improvement to the above technical solution, the inner diameter of the organic temperature sensing block is 0.1-0.3 mm larger than the outer diameter of the conductive post, the thickness of the organic temperature sensing block is 2-5 mm, and the outer diameter of the organic temperature sensing block is interference-fitted with the inner diameter of the shell, with an interference amount of 0.05-0.15 mm.

[0013] As a further improvement to the above technical solution, the insulating oil is No. 25 transformer oil, No. 45 transformer oil, or methyl silicone oil, with a breakdown voltage of not less than 35kV / 2.5mm, a kinematic viscosity of 10-40mm² / s at 40℃, and a flash point of not less than 140℃; an anti-aging stabilizer is added to the insulating oil to improve its long-term service stability.

[0014] As a further improvement to the above technical solution, the diameter of the inner metal disc is 30%-50% of the diameter of the bimetallic disc spring. The left side of the inner metal disc is in center contact with the right side of the bimetallic disc spring. The right contact surface of the inner metal disc is a spherical structure. The sphericity is optimized to match the flatness of the end face of the conductive post. Combined with the preload of the conductive spring, the effective contact area is increased, the contact resistance is stabilized within 0.3mΩ, and the contact pressure is 5-15N.

[0015] As a further improvement to the above technical solution, the conductive spring is made of beryllium bronze or tin bronze, with a wire diameter of 0.3-0.6 mm, a free length of 8-12 mm, a compression of 2-4 mm at room temperature, and a preload of 5-15 N. The preload of the conductive spring and the critical jump stress of the bimetallic disc spring are optimized through parameter matching, and the influence of the preload on the operating temperature is controlled within ±0.5℃. The thrust of the conductive spring throughout its stroke and the reset reaction force of the bimetallic disc spring are matched through mechanical selection, and the thrust of the spring is always greater than the reset reaction force of the spring throughout its stroke, thus avoiding reset jamming.

[0016] As a further improvement to the above technical solution, the fixing ring is made of 95% alumina ceramic or polytetrafluoroethylene. The inner diameter of the fixing ring is 0.5-1.0 mm smaller than the diameter of the bimetallic disc spring. The outer circle of the fixing ring is interference-fitted with the inner wall of the outer shell, and the interference amount is 0.1-0.2 mm.

[0017] As a further improvement to the above technical solution, the outer shell is made of 95% alumina ceramic or borosilicate glass, with a wall thickness of 0.8-1.5mm, a length of 20-30mm, and an inner diameter of 6-10mm. The two ends of the outer shell are sealed to the first and second cables with epoxy resin sealant containing toughening agents and adhesion promoters. The thermal expansion coefficient of the sealant matches the interface between the outer shell and the cables, and it can pass a wide temperature cycle leakage test from -40℃ to 180℃. The thickness of the sealant is 0.5-1.0mm.

[0018] As a further improvement to the above technical solution, the contact surfaces of the conductive plate, conductive pillar and inner metal disc are all coated with a thick silver alloy, with a coating thickness of 3-8 μm and a surface roughness Ra of no more than 1.6 μm.

[0019] As a further improvement to the above technical solution, the internal components of the shell are assembled using a coaxial positioning tooling press-fit process, and each part is selected and grouped according to dimensional tolerances, with an assembly coaxiality yield of not less than 95%.

[0020] A method of using the above-mentioned high-pressure resistant organic thermal fuse structure includes the following steps: S1. Pre-installation inspection: Remove the thermal fuse and visually inspect the casing for cracks or damage, and check the first and second cables for breaks or damaged insulation. Use a multimeter to measure the resistance between the first and second cables and confirm that the resistance is less than 0.1Ω. Check the sealing parts for cracks and ensure that there is no leakage of internal insulating oil. S2. Circuit connection: Connect the thermal fuse in series to the main circuit of the electrical equipment to be protected. The connection ends of the first and second cables are connected to the equipment wires by soldering. The soldering temperature is controlled at 260-300℃ and the soldering time does not exceed 3 seconds. After the soldering is completed, heat shrink tubing is sleeved on the connection part for insulation protection. S3. Fixed installation: Fix the thermal fuse to the surface of the heating element of the electrical equipment, ensuring that the distance between the organic temperature sensing block and the heating element is no more than 5mm; use clips or high-temperature resistant tape to fix it, and avoid mechanical squeezing or impact on the thermal fuse; S4. Functional Verification: After installation, power on the device to test its normal operation. Use a hot air gun to evenly heat the thermal fuse to the preset operating temperature to confirm that the device is powered off. Wait for the temperature to drop below the reset temperature to confirm that the device is powered on again. S5. Routine maintenance: Check the appearance and connection status of the thermal fuse every 6 months and perform a functional test once a year; if the casing is damaged, the insulating oil leaks, or it cannot disconnect or reset normally, replace it with the same model immediately.

[0021] Beneficial effects of the present invention Compared with the prior art, the present invention has the following significant advantages: 1. Significantly improved withstand voltage performance: This invention adopts a composite insulation structure of ceramic or glass shell and internal insulating oil, which improves the power frequency withstand voltage capability from 1.2-1.8kV of the existing technology to more than 3.5kV, and the withstand voltage level can reach more than AC250V / 10A, which can meet the protection requirements of high voltage electrical equipment.

[0022] 2. Significantly improved operating temperature accuracy: This invention uses an annular organic temperature sensing block with added high thermal conductivity filler, whose thermal conductivity is 2-3 times that of traditional metal temperature sensing structures. It can quickly and evenly transfer the ambient temperature to the bimetallic disc spring, reducing the operating temperature error from ±3.1-±5.2℃ in the existing technology to within ±1.8℃, making temperature protection more accurate and reliable.

[0023] 3. Excellent arc suppression effect: This invention reduces the arc duration from 42-85ms in the prior art to less than 8ms and the arc peak voltage from 380-620V to 120V through the physical barrier of the annular organic temperature sensing block, the air blowing effect of the gas-generating filler on the inner wall, and the chemical arc extinguishing effect of the insulating oil. This effectively avoids the occurrence of contact erosion and adhesion.

[0024] 4. Significantly extended service life: Thanks to the excellent arc suppression effect and the synergistic optimization of thick silver alloy contacts and anti-aging insulating oil, the load-bearing cycle life of this invention can reach more than 8,000 times, which is more than 6 times that of traditional low melting point alloy type thermal fuses and more than 2 times that of traditional organic material temperature sensing type thermal fuses.

[0025] 5. Fast response speed: This invention utilizes the instantaneous jump deformation characteristics of the bimetallic disc spring, and the circuit disconnection response time is only 15ms, which can quickly cut off the circuit in the early stage of abnormal temperature rise and provide more timely overheat protection.

[0026] 6. Simple structure and easy assembly: The invention has a compact overall structure and a small number of parts. With the coaxial positioning tooling press-fitting and parts sorting and assembly process, the assembly yield can reach more than 95%, the production cost is low, and it is suitable for large-scale industrial production.

[0027] 7. High feasibility for mass production and comprehensive coverage of precision levels: Through the process route of shaping heat treatment + finished product temperature classification and screening, the conventional level can stably achieve batch delivery of ±3℃, and the high-precision level can produce ±1℃ products on a large scale, taking into account both cost and high-end needs, and adapting to different application scenarios.

[0028] 8. Strong long-term sealing and environmental adaptability: The optimized sealant formula matches the interfacial thermal expansion coefficient and can pass the wide temperature cycle leakage test from -40℃ to 180℃; the reserved gas phase space compensates for the thermal expansion of insulating oil, solving the industry pain point of sealing failure under high temperature environment.

[0029] 9. High precision and strong anti-interference capability: The high thermal conductivity homogeneous spring material eliminates the influence of the temperature gradient of the outer heating, the optimized conductivity of the alloy controls the self-heating temperature rise, and the precise matching of the spring preload and the sudden stress further reduces mechanical interference, ensuring the long-term stability of the operating temperature in multiple dimensions.

[0030] 10. Comprehensive upgrade in conductivity and reset reliability: The spherical contact design increases the effective area of ​​the center contact, and the contact resistance is stabilized within 0.3mΩ; the matching of reset mechanical parameters eliminates the risk of jamming, and the stability and safety of the product in long-term operation are comprehensively improved. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure assembly of the present invention; Figure 2 This is a schematic diagram of the internal structure of the present invention under normal temperature conduction state; Figure 3 This is a schematic diagram of the internal structure of the present invention in the disconnected state when the operating temperature is reached; Figure 4 This is a three-dimensional structural diagram of the organic temperature sensing block in this invention; Figure 5 This is a schematic diagram of the layered structure of the bimetallic disc spring in this invention; Figure 6 This is the equivalent circuit diagram of the present invention; Figure 7 This is a flowchart illustrating the method of using the thermal fuse of the present invention.

[0032] The labels in the diagram represent the following: 1. Outer shell; 2. First cable; 3. Second cable; 4. Conductive plate; 5. Conductive spring; 6. Retaining ring; 7. Bimetallic disc spring; 8. Organic temperature sensing block; 9. Inner metal disc; 10. Conductive post. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1: Please refer to Figures 1-6 As shown, this embodiment provides a high-voltage-resistant organic thermal fuse structure, including a housing 1. The housing 1 is made of 95% alumina ceramic material, with a wall thickness of 1.0 mm, a length of 25 mm, and an inner diameter of 8 mm, exhibiting excellent insulation performance, high-temperature resistance, and mechanical strength. The two ends of the housing 1 are respectively sealed with epoxy resin sealant to a first cable 2 and a second cable 3, with a sealant thickness of 0.8 mm. The sealant contains 10% by mass of polyurethane toughening agent and 5% by mass of silane adhesion promoter, resulting in good thermal expansion coefficient matching with the interface of the ceramic housing and copper cables. No insulating oil leakage was observed after 100 cycles of testing from -40℃ to 180℃.

[0035] A conductive plate 4 is fixedly installed inside the outer casing 1 near one end of the first cable 2. The conductive plate 4 is made of silver-plated copper alloy with a plating thickness of 5μm. The conductive plate 4 is electrically connected to the first cable 2 by soldering. On the right side of the conductive plate 4, a conductive spring 5, a retaining ring 6, a bimetallic disc spring 7, an organic temperature sensing block 8, an inner metal disc 9, and a conductive post 10 are arranged coaxially in sequence. In this embodiment, the internal components are assembled by press-fitting using coaxial positioning fixtures. Each part is divided into 3 groups according to dimensional tolerances for assembly, and the coaxiality yield rate reaches 96%.

[0036] The conductive spring 5 is made of beryllium bronze with a wire diameter of 0.4 mm, a free length of 10 mm, a compression of 3 mm at room temperature, and provides a preload of 10 N. The left end of the conductive spring 5 is fixedly connected to the conductive plate 4 by welding, and the right end of the conductive spring 5 contacts the center of the left side of the bimetallic disc spring 7, ensuring good electrical contact between the bimetallic disc spring 7, the inner metal disc 9, and the conductive post 10. In this embodiment, the 10 N preload and the critical jump stress of the bimetallic disc spring 7 are optimized through simulation matching, and the temperature deviation caused by the preload fluctuation is ±0.3℃; at the same time, the minimum thrust of the conductive spring 5 throughout its stroke is 6 N, which is greater than the maximum reset reaction force of the bimetallic disc spring 7 (4.2 N), eliminating the risk of jamming during the reset process.

[0037] The retaining ring 6 is made of 95% alumina ceramic, and its outer circle is interference-fitted with the inner wall of the outer shell 1 with an interference of 0.15mm. It is fixedly installed on the inner wall of the outer shell 1. The inner diameter of the retaining ring 6 is 7mm, which is 0.5mm smaller than the diameter of the bimetallic disc spring 7. It is used to support the outer periphery of the bimetallic disc spring 7 and prevent it from shifting during deformation.

[0038] The bimetallic disc spring 7 is composed of an active layer and a passive layer, with the active layer being a manganese-nickel-copper alloy (thermal expansion coefficient 20×10). -6 / ℃), the passive layer is an iron-nickel alloy (thermal expansion coefficient 2×10). -6 / ℃), both layers are 0.1mm thick, with a total thickness of 0.2mm and a diameter of 7.5mm. The bimetallic disc spring 7 undergoes a shaping heat treatment at 350℃ for 2 hours to eliminate internal residual stress. The temperature deviation of a single batch is controlled within ±3℃, and after screening by temperature grading of finished products, the temperature deviation of high-precision gear operation can reach ±1℃. Its preset operating temperature is 125℃, the reset temperature is 80℃, the jump displacement is 0.8mm, and the jump response time is less than 10ms.

[0039] In this embodiment, the bimetallic disc spring 7 is made of a high thermal conductivity homogeneous bimetallic alloy with a radial thermal conductivity ≥45W / (m·K). The overall radial temperature difference of the spring is 0.3℃, and peripheral heating has no significant impact on the operating accuracy. After optimizing the alloy composition ratio, the overall resistivity of the spring is ≤8.5×10⁻⁶. -8 The temperature rise due to self-heating is 0.6℃ at a rated current of 10A, which has a negligible impact on the operating temperature error. The surface of the bimetallic disc spring 7 is plated with silver alloy with a thickness of 5μm to improve conductivity and corrosion resistance.

[0040] The organic temperature sensing block 8 has a ring-shaped structure and is coaxially sleeved on the outside of the conductive post 10. The organic temperature sensing block 8 is made of epoxy resin-based composite material with 40% alumina thermally conductive filler added by mass, with a thermal conductivity of 1.2 W / (m·K), a breakdown voltage of 25 kV / mm, and an operating temperature range of -40℃ to 180℃. The organic temperature sensing block 8 undergoes arc-resistant modification treatment, and its inner ring wall is uniformly mixed with 8% melamine-based gas-generating arc-extinguishing filler. Under the action of an electric arc, it instantly decomposes to generate high-pressure gas blowing, which works in conjunction with the transformer oil to extinguish the arc. The organic temperature sensing block 8 has an inner diameter of 3.2 mm, which is 0.2 mm larger than the outer diameter of the conductive post 10; a thickness of 3 mm; and an outer diameter of 8 mm, which is interference-fitted with the inner diameter of the outer shell 1 with an interference amount of 0.1 mm. The left side of the organic temperature sensing block 8 contacts the outer periphery of the right side of the bimetallic disc spring 7, enabling rapid transfer of ambient temperature to the bimetallic disc spring 7.

[0041] The inner metal disc 9 is made of silver-plated copper alloy with a plating thickness of 5μm and a diameter of 3mm, which is 40% of the diameter of the bimetallic disc spring 7. The inner metal disc 9 is positioned between the bimetallic disc spring 7 and the conductive post 10, with its left side in center contact with the right side of the bimetallic disc spring 7. Its right end face is a spherical structure with a radius of 15mm, which mates with the flat end face of the conductive post 10. Combined with a 10N spring preload, the effective contact area is increased by 30%, the contact resistance is stabilized below 0.25mΩ, and the contact pressure is 10N. The inner metal disc 9 can disperse the force of the bimetallic disc spring 7, ensuring uniform force on the conductive post 10 and improving conductivity.

[0042] The conductive post 10 is made of silver-plated copper alloy with a plating thickness of 5μm, a diameter of 3mm, and a length of 10mm. The right end of the conductive post 10 is electrically connected to the second cable 3 by soldering. The surface roughness Ra of the conductive plate 4, the conductive post 10, and the inner metal disc 9 is all 1.6μm, which can effectively reduce contact resistance and improve conductivity.

[0043] The internal cavity of the outer casing 1 is filled with No. 25 transformer oil, filling 85% of the cavity volume. A 15% gas phase space is reserved at the top of the cavity to compensate for the thermal expansion of the insulating oil up to 120℃, eliminating the risk of seal failure. The No. 25 transformer oil has a breakdown voltage of 40kV / 2.5mm, a kinematic viscosity of 25mm² / s at 40℃, and a flash point of 145℃. The oil contains 2% by mass of phenolic anti-aging stabilizer to improve long-term service stability. The insulating oil not only significantly improves overall insulation performance but also plays a role in heat dissipation and arc extinguishing.

[0044] The working principle of this embodiment is as follows: At room temperature, the bimetallic disc spring 7 maintains a stable state with its convex surface facing the conductive spring 5. The preload provided by the conductive spring 5 presses it firmly against the fixing ring 6. The bimetallic disc spring 7 is in close contact with the conductive post 10 through the inner metal disc 9, and the circuit is in a conductive state. The current sequentially passes through the first cable 2, the conductive plate 4, the conductive spring 5, the bimetallic disc spring 7, the inner metal disc 9, the conductive post 10, and the second cable 3 to form a loop.

[0045] When the ambient temperature rises to 125℃, heat is rapidly transferred to the bimetallic disc spring 7 through the outer shell 1 and the organic temperature-sensing block 8. Because the coefficient of thermal expansion of the active layer is much greater than that of the passive layer, the elongation of the active layer is greater than that of the passive layer, causing the internal stress inside the bimetallic disc spring 7 to gradually increase. When the internal stress exceeds the critical stability value of the disc structure, the bimetallic disc spring 7 undergoes a sudden jump and flip, with the convex surface facing the conductive post 10 and the center moving 0.8mm to the right. This pushes the inner metal disc 9 to the right, causing the inner metal disc 9 to quickly separate from the conductive post 10, breaking the circuit. At the moment of separation, the annular organic temperature-sensing block 8 forms a physical barrier, the gas-generating filler on the inner wall decomposes to produce a blowing effect, and the internal insulating oil rapidly cools and extinguishes the arc. This triple action effectively prevents contact erosion.

[0046] When the ambient temperature drops below 80℃, the internal stress direction inside the bimetallic disc spring 7 reverses, causing it to suddenly flip again, with the convex surface facing the conductive spring 5 once more. Under the preload of the conductive spring 5, the inner metal disc 9 re-contacts the conductive post 10, and the circuit returns to a conductive state. Since the spring's thrust throughout its entire stroke is always greater than the spring's reset reaction force, the reset process is smooth and without jamming.

[0047] Example 2: Figure 7 As shown, this embodiment details the usage method of the high-pressure-resistant organic thermal fuse structure described in Embodiment 1 above, specifically including the following steps: S1. Before installation, remove the thermal fuse and visually inspect the outer casing 1 for cracks or damage, and check the first cable 2 and the second cable 3 for breaks or damage to the insulation layer. Use a multimeter to measure the resistance between the first cable 2 and the second cable 3. Under normal conditions, the resistance should be less than 0.1Ω to confirm that the circuit is conducting. Check the sealant for cracks and ensure that there is no leakage of internal insulating oil.

[0048] S2. Circuit connection: Connect the thermal fuse in series to the circuit of the electrical equipment that needs protection. Ensure that the connection ends of the first cable 2 and the second cable 3 are firmly connected to the wires of the equipment circuit by soldering. The soldering temperature is controlled at 260-300℃ and the soldering time does not exceed 3 seconds to prevent the bimetallic disc spring 7 from deforming prematurely or the organic temperature sensing block 8 from aging due to high temperature. After the soldering is completed, put heat shrink tubing on the connection part for insulation protection.

[0049] S3. Fixed installation: Fix the thermal fuse near the heating component of the electrical equipment to ensure that the organic temperature sensing block 8 can directly sense the temperature of the heating component. The fixing method can be clip fixing or high-temperature resistant tape wrapping fixing. During installation, avoid mechanical squeezing or impact on the thermal fuse to prevent deformation of the bimetallic disc spring 7 or damage to the internal structure.

[0050] S4. Functional verification: After installation, power on the electrical equipment to confirm that the equipment is working properly; then use a hot air gun to evenly heat the outer shell 1 of the thermal fuse. When the temperature rises to the preset operating temperature, such as 125°C, observe whether the equipment is powered off to confirm that the thermal fuse can disconnect the circuit normally; when the temperature drops to the reset temperature, such as below 80°C, observe whether the equipment is powered on again to confirm that the thermal fuse can reset normally.

[0051] S5. Routine maintenance and replacement: Regularly check the appearance and connection status of the thermal fuse, and perform a functional test every 6 months. When the thermal fuse has a damaged casing, leaking insulating oil, or fails to disconnect or reset normally, it should be replaced with the same model of thermal fuse immediately. When replacing, the main power supply of the equipment should be disconnected first, and the operation should be carried out after the equipment has completely cooled down.

[0052] Example 3: This example provides a detailed description of the structure and working principle of the bimetallic disc reed 7: The bimetallic disc spring 7 is the core actuating element of the thermal fuse of this invention, and its structure is as follows: The bimetallic disc spring 7 is made of two metal alloys with significantly different coefficients of thermal expansion, an active layer and a passive layer, tightly bonded together by a hot-rolling composite process. The active layer is made of a manganese-nickel-copper alloy with a coefficient of thermal expansion of approximately 20 × 10⁻⁶. -6 / ℃, the passive layer is made of iron-nickel alloy with a thermal expansion coefficient of approximately 2×10. -6 / ℃, the thickness ratio of the two alloy layers is 1:1.

[0053] The composite metal strip is precision stamped into a disc-shaped structure with a diameter of 8mm, a thickness of 0.2mm, a radius of curvature of 15mm at room temperature, and a convex height of 0.5mm. The bimetallic disc spring 7, after stamping, undergoes a shaping heat treatment at 350℃ for 2 hours to eliminate internal residual stress and ensure stable sudden deformation characteristics. The temperature deviation of a single batch is controlled within ±3℃, and products with an accuracy of ±1℃ can be obtained after finished product grading and screening. The surface of the bimetallic disc spring 7 is coated with silver alloy with a coating thickness of 5-8μm to improve its conductivity and corrosion resistance.

[0054] The working principle of the bimetallic disc reed 7 is based on the difference in the thermal expansion coefficients of the two metal alloys and the sudden-jump mechanical properties of the disc structure: At room temperature: The bimetallic disc spring 7 remains stable with its convex surface facing the conductive spring 5. The preload provided by the conductive spring 5 presses it tightly against the fixing ring 6. The bimetallic disc spring 7 is in close contact with the conductive post 10 through the inner metal disc 9, and the circuit is in a conductive state. At this time, the internal stress inside the bimetallic disc spring 7 is in a state of equilibrium.

[0055] Heating Process: When the ambient temperature rises, heat is rapidly transferred to the bimetallic disc spring 7 through the outer shell 1 and the organic temperature sensing block 8. Because the coefficient of thermal expansion of the active layer is much greater than that of the passive layer, the elongation of the active layer is greater than that of the passive layer, causing the bimetallic disc spring 7 to bend and deform, and the internal stress gradually increases. The high thermal conductivity homogeneous alloy material ensures uniform radial temperature of the spring, preventing significant temperature differences from forming during peripheral heating; the optimized alloy conductivity results in extremely low self-heating temperature rise under rated current, which does not interfere with the operating temperature determination. When the temperature rises to the preset operating temperature, the internal stress exceeds the critical stability value of the disc structure, causing the bimetallic disc spring 7 to momentarily jump and flip, with the convex surface facing the conductive post 10.

[0056] Circuit disconnection: After the bimetallic disc spring 7 suddenly jumps and flips, its center moves to the right by about 0.8 mm, pushing the inner metal disc 9 to the right, causing the inner metal disc 9 to quickly separate from the conductive post 10, thus disconnecting the circuit. The entire jump process takes less than 10 ms, and the action is rapid and reliable; at the moment of separation, the gas-generating filler and insulating oil work together to extinguish the arc, effectively preventing the aggravation of contact arcing.

[0057] Cooling Reset: When the ambient temperature drops below the reset temperature, the internal stress direction inside the bimetallic disc spring 7 reverses, causing a sudden jump and flip, with the convex surface facing the conductive spring 5 again. Under the preload of the conductive spring 5, the inner metal disc 9 re-contacts the conductive post 10, and the circuit returns to conduction. The spring's thrust throughout its entire stroke is always greater than the spring's reset reaction force, preventing reset jamming.

[0058] Example 4: This example provides a high-pressure resistant organic thermal fuse structure, which is basically the same as that in Example 1, except that: The organic temperature sensing block 8 is made of phenolic resin-based composite material with 35% aluminum nitride thermally conductive filler, with a thermal conductivity of 1.5 W / (m·K) and a breakdown voltage of 22 kV / mm; the inner ring inner wall is filled with aluminum hydroxide gas-generating arc-quenching filler with a filler mass fraction of 10%.

[0059] The insulating oil is made of methyl silicone oil, with a breakdown voltage of 38kV / 2.5mm, a kinematic viscosity of 20mm² / s at 40℃, and a flash point of 300℃; the oil contains a composite anti-aging stabilizer.

[0060] The preset operating temperature of the bimetallic disc spring 7 is 135℃, and the reset temperature is 90℃.

[0061] The performance test results of this embodiment show that its operating temperature error is ±1.5℃, power frequency withstand voltage is 3.6kV, arc duration is 7ms, and load cycle life is 10,000 times. All performance indicators are better than those of Embodiment 1, and it is particularly suitable for the protection of high-voltage electrical equipment in high-temperature environments.

[0062] Example 5: This example provides a high-pressure resistant organic thermal fuse structure, which is basically the same as that in Example 1, except that: The outer casing 1 is made of borosilicate glass with a wall thickness of 1.2 mm; The retaining ring 6 is made of polytetrafluoroethylene; The conductive spring 5 is made of tin bronze and has a preload of 8N. The bimetallic disc spring 7 has a diameter of 8mm and a sudden displacement of 0.9mm.

[0063] The performance test results of this embodiment show that its power frequency withstand voltage is 3.4kV, the operating temperature error is ±1.9℃, the arc duration is 9ms, and the load cycle life is 8500 cycles. It can meet the protection requirements of general high-voltage electrical equipment, and the production cost is lower, making it suitable for mass civilian applications.

[0064] Comparative Example 1 To verify the technical effectiveness of the high-pressure-resistant organic thermal fuse structure of the present invention, this embodiment selects two typical thermal fuses in the prior art as comparative examples and conducts performance comparison tests with Embodiment 1 of the present invention under the same test conditions.

[0065] Comparative Example 1-1: A commercially available low-melting-point alloy thermal fuse, model RH125, rated voltage AC250V, rated current 5A, and nominal operating temperature 125℃.

[0066] Comparative Examples 1-2: Commercially available traditional organic temperature-sensitive fuse, model TF125, rated voltage AC250V, rated current 7A, nominal operating temperature 125℃.

[0067] Example 1 of the present invention: A high-pressure resistant organic thermal fuse prepared according to the technical solution of the present invention has a rated voltage of AC250V, a rated current of 10A, and a nominal operating temperature of 125℃.

[0068] 1. Test conditions All tests were conducted under standard conditions of 25℃±2℃ and 45%-55% relative humidity. Testing equipment included: a high and low temperature alternating test chamber (accuracy ±0.5℃), a power frequency withstand voltage tester, a high-speed arc tester, a high-precision temperature recorder (sampling frequency 100Hz), and a digital multimeter (accuracy 0.01Ω). All samples were conditioned for 24 hours under standard conditions before testing.

[0069]

[0070] As can be seen from the data in the table above, Embodiment 1 of the present invention is significantly superior to the two conventional thermal fuses in the prior art in all key performance indicators: Withstand voltage performance: This invention improves the power frequency withstand voltage capability from 1.2-1.8kV in the existing technology to 3.5kV through a composite insulation structure of ceramic shell and internal insulating oil. It completely solves the problem of insulation breakdown of traditional thermal fuses under high voltage environment and can meet the protection requirements of AC250V / 10A and above high voltage electrical equipment.

[0071] Operating temperature accuracy: This invention uses a high thermal conductivity organic temperature sensing block 8, combined with a high thermal conductivity homogeneous spring and optimized conductivity design. Its thermal conductivity is 2-3 times that of traditional metal temperature sensing structures, which can quickly and uniformly transfer the ambient temperature to the bimetallic disc spring 7, reducing the operating temperature error from ±3.1-±5.2℃ in the prior art to ±1.8℃, significantly improving the accuracy of temperature protection.

[0072] Arc suppression effect: This invention reduces the arc duration from 42-85ms in the prior art to 8ms and the arc peak voltage from 380-620V to 120V through the physical barrier of the annular organic temperature sensing block, the air blowing effect of the gas-generating filler and the chemical arc extinguishing effect of the insulating oil. This effectively avoids the occurrence of contact erosion and adhesion.

[0073] Service life and response speed: Thanks to the excellent arc suppression effect, thick silver alloy contacts and anti-aging oil design, the load cycle life of this invention exceeds 8,000 times, which is more than 6 times that of traditional low melting point alloy type and more than 2 times that of traditional organic material temperature sensing type; at the same time, by utilizing the instantaneous jump deformation characteristics of bimetallic disc spring 7, the circuit disconnection response time is only 15ms, which can quickly cut off the circuit in the early stage of abnormal temperature rise and provide more reliable overheat protection.

[0074] Furthermore, this invention addresses the core pain points of mass production implementation through process optimization: coaxial tooling press-fitting and parts assembly achieve an assembly yield of over 95%; shaping heat treatment and graded screening balance the mass production efficiency of conventional grades with the supply capacity of high-precision grades; and sealant optimization and thermal expansion compensation design ensure long-term service reliability. The overall solution combines technological advancement with engineering feasibility, making it suitable for large-scale industrial applications.

[0075] Withstand voltage performance: This invention improves the power frequency withstand voltage capability from 1.2-1.8kV in the existing technology to 3.5kV through a composite insulation structure of ceramic shell and internal insulating oil. It completely solves the problem of insulation breakdown of traditional thermal fuses under high voltage environment and can meet the protection requirements of AC250V / 10A and above high voltage electrical equipment.

[0076] Operating temperature accuracy: This invention uses a high thermal conductivity organic temperature sensing block 8, whose thermal conductivity is 2-3 times that of traditional metal temperature sensing structures. It can quickly and uniformly transfer the ambient temperature to the bimetallic disc spring 7, reducing the operating temperature error from ±3.1-±5.2℃ in the prior art to ±1.8℃, which significantly improves the accuracy of temperature protection.

[0077] Arc suppression effect: This invention reduces the arc duration from 42-85ms in the prior art to 8ms and the arc peak voltage from 380-620V to 120V through the dual action of physical barrier of the annular organic temperature sensing block 8 and chemical arc extinguishing of insulating oil, effectively avoiding contact erosion and adhesion.

[0078] Service life and response speed: Thanks to the excellent arc suppression effect, the cyclic operation life of this invention exceeds 10,000 times, which is more than 8 times that of traditional low melting point alloy type and more than 2.8 times that of traditional organic material temperature sensing type; at the same time, by utilizing the instantaneous jump deformation characteristics of bimetallic disc spring 7, the circuit disconnection response time is only 15ms, which can quickly cut off the circuit in the early stage of abnormal temperature rise and provide more reliable overheat protection.

[0079] Compared with existing technologies, this invention solves multiple technical problems of traditional thermal fuses, such as insufficient voltage resistance, low operating temperature accuracy, poor arc suppression effect, and short service life, through innovative structural design. The overall performance is comprehensively improved, and it has significant technological progress and outstanding beneficial effects.

[0080] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended technical solutions and their equivalents.

Claims

1. A high-pressure-resistant organic thermal fuse structure, characterized in that: The device includes an outer shell (1), with a first cable (2) and a second cable (3) sealed and connected to both ends of the outer shell (1); a conductive plate (4) is fixedly installed inside the outer shell (1) near the end of the first cable (2), and the conductive plate (4) is electrically connected to the first cable (2); a conductive spring (5), a fixing ring (6), a bimetallic disc spring (7), an organic temperature sensing block (8), an inner metal disc (9), and a conductive post (10) are arranged coaxially on the right side of the conductive plate (4). The left end of the conductive spring (5) is fixedly connected to the conductive plate (4), and the right end is in contact with the center of the left side of the bimetallic disc spring (7); the fixing ring (6) is fixedly installed on the inner wall of the outer shell (1) to support the edge of the bimetallic disc spring (7); the organic temperature sensing block (8) is coaxially sleeved in a ring on the outside of the conductive post (10), and its left side is in contact with the right side of the bimetallic disc spring (7); the inner metal disc (9) is disposed between the bimetallic disc spring (7) and the conductive post (10); the right end of the conductive post (10) is electrically connected to the second cable (3); the internal cavity of the outer shell (1) is filled with insulating oil.

2. The high-pressure resistant organic thermal fuse structure according to claim 1, characterized in that: The bimetallic disc spring (7) is made of two metal alloys with different coefficients of thermal expansion. It has the characteristic that the convex surface faces the conductive spring (5) at room temperature and jumps and flips to face the conductive post (10) when the preset operating temperature is reached. The bimetallic disc spring (7) is subjected to a heat treatment of 320-380℃ for 1.5-2.5h. The operating temperature deviation of a single batch is controlled within ±3℃. After the finished product temperature is graded and screened, the high-precision gear operating temperature deviation can reach ±1℃.

3. The high-pressure resistant organic thermal fuse structure according to claim 2, characterized in that: The organic temperature sensing block (8) is made of thermosetting epoxy resin or phenolic resin-based composite material with added thermally conductive filler. Its thermal conductivity is not less than 0.8 W / (m·K) and its breakdown voltage is not less than 20 kV / mm. The organic temperature sensing block (8) is modified to withstand electric arcs. The inner wall of the inner ring is filled with gas-generating arc-extinguishing filler. Under the action of electric arc, it can generate a gas blowing effect and synergistically extinguish the arc with the insulating oil.

4. The high-pressure resistant organic thermal fuse structure according to claim 3, characterized in that: The inner diameter of the organic temperature sensing block (8) is 0.1-0.3 mm larger than the outer diameter of the conductive column (10), and the thickness is 2-5 mm. The outer diameter matches the inner diameter of the outer shell (1).

5. The high-pressure resistant organic thermal fuse structure according to claim 4, characterized in that: The insulating oil is transformer oil or silicone oil with a breakdown voltage of not less than 35kV / 2.5mm and a kinematic viscosity of 10-40mm² / s at 40℃. The insulating oil contains an anti-aging stabilizer, and the filling amount is 85% of the internal cavity volume of the shell (1). A gas phase space is reserved at the top of the cavity to compensate for the thermal expansion of the insulating oil.

6. The high-pressure resistant organic thermal fuse structure according to claim 1, characterized in that: The diameter of the inner metal disc (9) is smaller than that of the bimetallic disc spring (7), and its left side is in contact with the center of the right side of the bimetallic disc spring (7). The right contact surface is a spherical structure. The contact surfaces of the conductive plate (4), the inner metal disc (9) and the conductive post (10) are coated with a thick silver alloy. Combined with the preload of the conductive spring (5), the effective contact area can be increased and the contact resistance is stabilized within 0.3mΩ.

7. The high-pressure resistant organic thermal fuse structure according to claim 1, characterized in that: The conductive spring (5) is made of beryllium bronze or tin bronze, with a compression of 2-4 mm at room temperature and a preload of 5-15 N. The preload of the conductive spring (5) is matched with the critical jump stress of the bimetallic disc spring (7), and the effect of the preload on the operating temperature is controlled within ±0.5℃. The spring thrust is always greater than the reset reaction force of the bimetallic disc spring (7) throughout its stroke, thus avoiding reset jamming.

8. The high-pressure resistant organic thermal fuse structure according to claim 1, characterized in that: The fixing ring (6) is made of ceramic or high-temperature resistant engineering plastic. Its inner diameter is smaller than that of the bimetallic disc spring (7). The outer circle is interference-fitted with the inner wall of the outer shell (1). The components inside the outer shell are assembled using a coaxial positioning tooling press-fit process. Each part is selected and matched according to the dimensional tolerance. The coaxiality of the assembly is not less than 95%.

9. The high-pressure resistant organic thermal fuse structure according to claim 1, characterized in that: The outer shell (1) is made of ceramic or glass. The two ends of the outer shell (1) are sealed to the first cable (2) and the second cable (3) by epoxy resin sealant with added toughening agent and adhesion promoter. The thermal expansion coefficient of the sealant matches the connection interface and can pass the wide temperature cycle leakage test of -40℃ to 180℃ to ensure that the internal insulating oil does not leak.

10. The high-pressure-resistant organic thermal fuse structure according to claim 1, characterized in that: The conductive plate (4), conductive pillar (10) and inner metal disc (9) are all made of silver-plated copper or brass, with a surface roughness Ra of no more than 1.6 μm; the bimetallic disc spring (7) is made of a high thermal conductivity homogeneous bimetallic alloy material, with an overall radial temperature difference of less than 0.5℃; and the bimetallic alloy has been optimized in terms of composition ratio, with a self-heating temperature rise of less than 0.8℃ under rated current.

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