Three-terminal fuse

Abstract

A three-terminal fuse comprises a heating resistor, an insulating layer, an intermediate electrode and a fusible alloy sheet which are sequentially arranged on a substrate from bottom to top, a fluxing agent is coated on the fusible alloy sheet, and a high-viscosity silicone oil layer is further coated on the upper surface of the fluxing agent. The viscosity of the high-viscosity silicone oil layer ranges from 20,000 cs to 1,000,000 cs. According to the utility model, the retention state of the fluxing agent on the fusible alloy sheet can be ensured, the efficiency and the reliability of timely fusing of the fuse link are ensured, and the stability and the high-current pulse impact resistance of the fuse are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit protection elements, and more particularly to a three-terminal fuse with high stability and high current pulse impact resistance. Background Art

[0002] Three-terminal fuses provide overcurrent and overvoltage protection for high-energy batteries, particularly lithium-ion batteries. Serving as secondary protection for large-capacity lithium-ion batteries in electric vehicles, these fuses are required to withstand 20 high-current pulses of 700-1500A, 800 microseconds, without opening. Existing products struggle to meet this requirement.

[0003] The existing three-terminal fuse usually has a heating element on a ceramic substrate, covered with a glass insulating layer, a heating element electrode, and a pair of electrodes on both sides. An alloy melt sheet is welded on the heating element electrode, and the alloy melt sheet is coated with flux. Its main function is to change the surface tension of the liquid alloy when the alloy melts, and to remove the alloy oxides, causing it to shrink rapidly to achieve the purpose of rapid cutting. The retention of the flux on the fusible alloy sheet will affect the operation speed and reliability. For the flux coated on the alloy melt sheet, in a high temperature environment, such as during reflow soldering, the flux melts into liquid and flows, making the flux coating on the surface of the alloy melt sheet uneven and may not be able to maintain its original position. The effective flux on the alloy melt sheet is reduced, affecting the timely melting of the fuse element, and reducing its efficiency and reliability.

[0004] In view of this, the designer of this invention has deeply considered the many shortcomings and inconveniences caused by the imperfect structural design of the existing three-terminal fuse, and actively researched, improved and trial-produced it to develop and design this creation. Utility Model Content

[0005] The purpose of the utility model is to provide a three-terminal fuse, which can ensure that the flux is retained on the fusible alloy sheet, ensure the efficiency and reliability of the fuse body to melt in time, and improve the stability of the fuse and its ability to withstand high current pulse impact.

[0006] In order to achieve the above objectives, the solution of the present invention is:

[0007] A three-terminal fuse comprises a heating resistor, an insulating layer, an intermediate electrode and a fusible alloy sheet arranged in sequence from bottom to top on a substrate, the fusible alloy sheet is coated with a flux, and the upper surface of the flux is also coated with a layer of high-viscosity silicone oil.

[0008] Furthermore, the viscosity of the high-viscosity silicone oil layer ranges from 20,000 cs to 1,000,000 cs.

[0009] Furthermore, the viscosity of the high viscosity silicone oil layer ranges from 50,000 cs to 500,000 cs.

[0010] Furthermore, the viscosity of the high-viscosity silicone oil layer ranges from 100,000 to 300,000 cs.

[0011] Furthermore, the high viscosity silicone oil is methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, methylchlorophenyl silicone oil, methylethoxy silicone oil, methyltrifluoropropyl silicone oil, methylvinyl silicone oil, methylhydroxy silicone oil, ethyl hydrogen silicone oil, hydroxy hydrogen silicone oil or cyanide silicone oil.

[0012] Furthermore, a pair of main electrodes are formed on the substrate on both sides of the heating resistor. The two main electrodes are located on both sides of the middle electrode. One end of the heating resistor is connected to the head of the middle electrode, and the other end is connected to a heating electrode terminal. The insulating layer covers the heating resistor.

[0013] Furthermore, both sides of the fusible alloy sheet are welded to the two main electrodes, and the middle of the fusible alloy sheet is welded to the middle electrode. The middle electrode is T-shaped, and the head of the middle electrode is connected to one side of the inner electrode of the heating resistor.

[0014] Furthermore, the insulating layer is a glass glaze insulating layer, and the substrate is a ceramic substrate.

[0015] Furthermore, an upper cover is provided above the substrate.

[0016] With the above-described structure, the three-terminal fuse of the present invention utilizes a layer of high-viscosity silicone oil coated on the flux surface, which helps to keep the flux fixed in its original area during high-temperature melting and prevent it from flowing away. This ensures that the flux remains on the fusible alloy sheet, preventing it from affecting the timely melting, performance, and reliability of the fuse link. This improves the fuse's stability, resistance to high-current pulse shocks, and breaking capacity. Furthermore, the high-temperature-resistant, stable, high-viscosity silicone oil coating the flux surface prevents oxidation and enhances product stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the three-dimensional structure of the utility model (the upper cover is omitted, showing part of the heating resistor and part of the flux);

[0018] Figure 2 It is a top view schematic diagram of the utility model;

[0019] Figure 3 It is a cross-sectional schematic diagram of the present utility model. DETAILED DESCRIPTION

[0020] In order to further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0021] Combine Figures 1 to 3As shown, the utility model discloses a three-terminal fuse, which includes a heating resistor 2, an insulating layer 3, an intermediate electrode 4 and a fusible alloy sheet 5 arranged in sequence from bottom to top on the upper surface of a substrate 1, and a flux 6 is coated on the fusible alloy sheet 5. The flux 6 can help the fusible alloy sheet 5 to melt faster. This is a prior art and will not be described in detail here. Among them, a pair of main electrodes 7 can also be provided on the substrate 1 on both sides of the heating resistor 2. The two main electrodes 7 are respectively located on both sides of the intermediate electrode 4. One end of the heating resistor 2 is connected to the head of the intermediate electrode 4, and the other end is connected to a heating electrode terminal 9. The heating electrode terminal 9 is located on the substrate 1 and can be located on the bottom surface of one side of the heating resistor 2. The insulating layer 3 covers the heating resistor 2, forming an insulation separation between it and the intermediate electrode on the insulating layer 3. The two sides of the fusible alloy sheet 5 are welded to the two main electrodes 7, and the fusible alloy sheet is also welded to the intermediate electrode 4, so that the middle part of the fusible alloy sheet 5 is welded to the intermediate electrode 4. In this embodiment, the middle electrode 4 is T-shaped, with its tip connected to one side of the inner electrode of the heating resistor 2. The insulating layer 3 can be a glass glaze insulating layer, which provides both insulation and thermal conductivity. The substrate 1 can be a ceramic substrate. An upper cover 11 is also provided above the substrate 1, housing the components of the three-terminal fuse.

[0022] The main improvement of the present invention is that a layer of heat-conducting medium is also coated on the upper surface of the flux 6, and the heat-conducting medium is a high-viscosity silicone oil layer 8. The high-viscosity silicone oil layer 8 has a high viscosity, and coating the upper surface of the flux 6 can make the flux 6 less likely to flow.

[0023] Specifically, the viscosity of the high-viscosity silicone oil layer ranges from 20,000 cs to 1,000,000 cs. Preferably, the viscosity of the high-viscosity silicone oil layer ranges from 50,000 cs to 500,000 cs. More preferably, the viscosity of the high-viscosity silicone oil layer ranges from 100,000 cs to 300,000 cs. The high-viscosity silicone oil can be methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, methylchlorophenyl silicone oil, methylethoxy silicone oil, methyltrifluoropropyl silicone oil, methylvinyl silicone oil, methylhydroxy silicone oil, ethyl hydrogen silicone oil, hydroxy hydrogen silicone oil, or cyanide silicone oil. Preferably, the high-viscosity silicone oil can be methyl silicone oil.

[0024] Due to its high-temperature resistance, excellent thermal conductivity, and low viscosity-temperature coefficient, high-viscosity silicone oil exhibits minimal viscosity change at high temperatures and is less prone to flow. Therefore, it reliably secures the flux in its original location, preventing it from dispersing freely. This ensures that the flux 6 remains on the fusible alloy sheet 5. Furthermore, any heat generated by a transient pulse current can be dispersed through this layer of high-viscosity silicone oil, thereby improving the fuse's ability to withstand pulse currents. Furthermore, since this layer of high-viscosity silicone oil covers the melt (fusible alloy sheet 5), its high insulation and high-temperature resistance means that when the melt is melted by current, the arc generated by the high-viscosity silicone oil is isolated and weakened when passing through it, thereby enhancing the fuse's breaking capacity. Another benefit is that the high-temperature-resistant and stable high-viscosity silicone oil coating the flux prevents direct contact with air, preventing oxidation in prolonged high-temperature environments and improving product stability.

[0025] The above embodiments and drawings do not limit the product form and style of the present invention. Any appropriate changes or modifications made by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present invention.

Claims

1. A three-terminal fuse, characterized in that: The substrate is provided with a heating resistor, an insulating layer, an intermediate electrode and a fusible alloy sheet in sequence from bottom to top. The fusible alloy sheet is coated with a flux, and the upper surface of the flux is also coated with a high-viscosity silicone oil layer.

2. A three-terminal fuse according to claim 1, characterized in that: The viscosity of the high viscosity silicone oil layer ranges from 20,000 cs to 1,000,000 cs.

3. A three-terminal fuse according to claim 2, characterized in that: The viscosity of the high viscosity silicone oil layer ranges from 50,000 cs to 500,000 cs.

4. A three-terminal fuse as claimed in claim 3, characterized in that: The viscosity of the high viscosity silicone oil layer ranges from 100,000 to 300,000 cs.

5. A three-terminal fuse according to any one of claims 1 to 4, characterized in that: The high viscosity silicone oil is methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, methylchlorophenyl silicone oil, methylethoxy silicone oil, methyltrifluoropropyl silicone oil, methylvinyl silicone oil, methylhydroxy silicone oil, ethyl hydrogen silicone oil, hydroxy hydrogen silicone oil or cyanide silicone oil.

6. A three-terminal fuse according to claim 1, characterized in that: A pair of main electrodes are formed on the substrate on both sides of the heating resistor. The two main electrodes are located on both sides of the middle electrode. One end of the heating resistor is connected to the head of the middle electrode, and the other end is connected to a heating electrode terminal. The insulating layer covers the heating resistor.

7. A three-terminal fuse according to claim 6, characterized in that: The two sides of the fusible alloy sheet are welded to the two main electrodes, and the middle of the fusible alloy sheet is welded to the middle electrode. The middle electrode is T-shaped, and the head of the middle electrode is connected to one side of the inner electrode of the heating resistor.

8. The three-terminal fuse according to claim 1, characterized in that: The insulating layer is a glass glaze insulating layer, and the substrate is a ceramic substrate.

9. The three-terminal fuse according to claim 1, wherein: An upper cover is also provided above the base plate.

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