Resin encapsulated lightning stroke surge protector with thermal fusing protection

Abstract

The utility model relates to a resin-encapsulated lightning stroke surge protector with thermal fusing protection, which comprises a pressure-sensitive chip, a first electrode layer, a second electrode layer and a thermal fusing wire, and is characterized in that the first electrode layer is arranged at the upper end of the pressure-sensitive chip, and the second electrode layer is arranged at the lower end of the pressure-sensitive chip; a first pin is arranged on the first electrode layer, an insulating spacer is arranged on the first electrode layer, a second pin is arranged on the insulating spacer, the thermal fuse wire is arranged on the insulating spacer, and one end of the thermal fuse wire is electrically connected with one end of the second pin. The other end of the thermal fuse wire is electrically connected with the first electrode layer and one end of the first pin through a low-melting-point welding spot; the second electrode layer is provided with a third pin, and one end of the third pin is electrically connected with the second electrode layer. According to the utility model, open circuit can be carried out after the temperature rises to a set temperature, thereby avoiding open fire.

Description

Technical Field

[0001] The utility model relates to the technical field of surge protectors, and particularly to a resin-encapsulated lightning surge protector with thermal fuse protection. Background Art

[0002] A varistor is a resistive element with non-linear volt-ampere characteristics. Its main function is to unload transient overvoltage in a circuit to protect other components in the circuit. The varistor is connected in parallel with the protected component in the circuit. When the normal circuit voltage is normal, the impedance of the varistor body is very high and the power consumption is very low, and it is in a non-operating servo state, having almost no impact on the circuit. When a voltage higher than the working threshold of the varistor appears in the circuit, the resistance value of the varistor chip body will rapidly decrease, so as to absorb the energy of the overvoltage and convert it into heat and dissipate it, thereby protecting the electronic components at the rear end of the line from damage by overvoltage.

[0003] The varistor can withstand instantaneous overvoltage and can return to the non-operating servo state, but continuous long-term overvoltage will cause the temperature of the varistor body to rise continuously, which may cause the encapsulation layer of the varistor to catch fire and burn; therefore, it is necessary to solve the problem that the varistor causes open fire combustion due to long-term continuous overvoltage, self-heat accumulation, and rising body temperature. Content of the Utility Model

[0004] The utility model aims to solve at least one of the above technical problems in the prior art to a certain extent. For this reason, an object of the utility model is to provide a resin-encapsulated lightning surge protector with thermal fuse protection, which can cut off the circuit after the temperature rises to a set temperature and avoid causing open fire.

[0005] The technical solution for the utility model to solve the above technical problems is as follows: A resin-encapsulated lightning surge protector with thermal fuse protection includes a varistor chip, a first electrode layer, a second electrode layer, and a thermal fuse. The first electrode layer is fixedly disposed on the upper end of the varistor chip, and the second electrode layer is fixedly disposed on the lower end of the varistor chip;

[0006] A first lead is fixedly disposed on the first electrode layer, an insulating gasket is fixedly disposed on the first electrode layer, a second lead is fixedly disposed on the insulating gasket, the thermal fuse is fixedly disposed on the insulating gasket, one end of the thermal fuse is electrically connected to one end of the second lead, the other end of the second lead extends and deviates from the varistor chip, the other end of the thermal fuse is electrically connected to the first electrode layer and one end of the first lead through a low-melting-point solder joint, and the other end of the first lead extends and deviates from the varistor chip;

[0007] A third pin is fixedly arranged on the second electrode layer. One end of the third pin is electrically connected to the second electrode layer, and the other end of the third pin extends and deviates from the varistor chip.

[0008] The beneficial effects of the present utility model are as follows: The third pin, the second electrode layer, the varistor chip, the first electrode layer, the low-melting-point solder joint, the thermal fuse, and the first pin can withstand instantaneous overvoltage. Also, by utilizing the low-melting-point characteristics of the low-melting-point solder joint and the thermal fuse, after the temperature of the varistor chip continuously rises to the set temperature, the low-melting-point solder joint becomes in a molten state, and the thermal fuse deforms and disconnects from the first electrode layer to form an open circuit, avoiding the occurrence of open flames.

[0009] On the basis of the above technical solution, the present utility model can be further improved as follows.

[0010] Further, the thermal fuse is of a hollow structure, and the inside of the thermal fuse is filled with a low-melting-point solid flux.

[0011] The beneficial effect of adopting the above further solution is that the low-melting-point solid flux is heated to become in a molten state and flows out, causing the thermal fuse to shrink and deform towards its hollow structure, thereby disconnecting the thermal fuse from the first electrode layer to form an open circuit and avoiding continuous temperature rise and ignition of the varistor chip.

[0012] Further, the second pin is fixedly connected to the insulating gasket through a fixing glue.

[0013] The beneficial effect of adopting the above further solution is that the fixing glue can stabilize the second pin, is not easy to age, and prolongs the service life of the surge protector.

[0014] Further, an insulating encapsulation layer is wrapped on the varistor chip. The insulating encapsulation layer wraps the first electrode layer, the second electrode layer, the thermal fuse, the low-melting-point solder joint, and the insulating gasket. The insulating encapsulation layer also wraps the ends of the first pin, the second pin, and the third pin on the varistor chip.

[0015] The beneficial effect of adopting the above further solution is that by using the insulating encapsulation layer to wrap the varistor chip, the first electrode layer, the second electrode layer, the thermal fuse, the first pin, the insulating gasket, the second pin, the low-melting-point solder joint, and the third pin, moisture-proof, moisture-resistant, and electrical insulation functions of the surge protector are realized. Description of the Drawings

[0016] Figure 1 It is a top view of a resin-encapsulated lightning surge protector with thermal fuse protection according to the present utility model;

[0017] Figure 2 It is a bottom view of a resin-encapsulated lightning surge protector with thermal fuse protection according to the present utility model;

[0018] Figure 3 This is a schematic structural diagram of a resin-encapsulated lightning surge protector with thermal fuse protection for the present utility model.

[0019] In the attached drawings, the list of components represented by each reference numeral is as follows:

[0020] 1. Varistor chip, 2. First electrode layer, 3. Second electrode layer, 4. Thermal fuse, 5. First lead, 6. Insulating gasket, 7. Second lead, 8. Low-melting-point solder joint, 9. Third lead, 10. Insulating encapsulation layer. Specific embodiments

[0021] The principles and features of the present utility model will be described below in conjunction with the attached drawings. The examples given are only for explaining the present utility model and are not intended to limit the scope of the present utility model.

[0022] As Figures 1 to 3 shown, a resin-encapsulated lightning surge protector with thermal fuse protection includes a varistor chip 1, a first electrode layer 2, a second electrode layer 3, and a thermal fuse 4. The first electrode layer 2 is fixedly disposed on the upper end of the varistor chip 1, and the second electrode layer 3 is fixedly disposed on the lower end of the varistor chip 1;

[0023] A first lead 5 is fixedly provided on the first electrode layer 2, an insulating gasket 6 is fixedly provided on the first electrode layer 2, a second lead 7 is fixedly provided on the insulating gasket 6, the thermal fuse 4 is fixedly disposed on the insulating gasket 6, one end of the thermal fuse 4 is electrically connected to one end of the second lead 7, the other end of the second lead 7 extends and deviates from the varistor chip 1, the other end of the thermal fuse 4 is electrically connected to the first electrode layer 2 and one end of the first lead 5 through a low-melting-point solder joint 8, and the other end of the first lead 5 extends and deviates from the varistor chip 1;

[0024] A third lead 9 is fixedly provided on the second electrode layer 3, one end of the third lead 9 is electrically connected to the second electrode layer 3, and the other end of the third lead 9 extends and deviates from the varistor chip 1.

[0025] In the specific application of this embodiment, due to lightning strikes or electromagnetic induction, etc., a momentary high voltage will be generated in the circuit. The high voltage will cause the varistor chip 1 to change from a high-resistance state to a low-resistance state. The high voltage is discharged in sequence through the third lead 9, the second electrode layer 3, the varistor chip 1, the first electrode layer 2, the low-melting-point solder joint 8, the thermal fuse 4, and the first lead 5, thereby protecting the components at the rear end;

[0026] When a fault occurs in the circuit, causing the voltage to continuously exceed the maximum operating voltage that the varistor chip 1 can withstand, the temperature of the varistor chip 1 will continuously rise, and the heat will be conducted to the low-melting solder joint 8 and the thermal fuse 4 through the first electrode layer 2; after the low-melting solder joint 8 and the thermal fuse 4 absorb enough heat from the varistor chip 1 and reach their melting points, they start to become molten. After the low-melting solder joint 8 melts, it diffuses to the surrounding area, and the flux inside the thermal fuse 4 flows out due to heat, causing the thermal fuse 4 to deform, so that the thermal fuse 4 is disconnected from the first electrode layer 2 to form an open circuit, cutting off the voltage and preventing the varistor chip 1 from continuously heating up and catching fire.

[0027] In this embodiment, the third pin 9, the second electrode layer 3, the varistor chip 1, the first electrode layer 2, the low-melting solder joint 8, the thermal fuse 4 and the first pin 5 can withstand instantaneous overvoltage. Also, by utilizing the low-melting-point characteristics of the low-melting solder joint 8 and the thermal fuse 4, after the temperature of the varistor chip 1 continuously rises to the set temperature, the low-melting solder joint 8 becomes molten, and the thermal fuse 4 deforms and is disconnected from the first electrode layer 2 to form an open circuit, avoiding the occurrence of open flames.

[0028] In the above embodiment, the thermal fuse 4 is a hollow structure, and the thermal fuse 4 is filled with a low-melting-point solid flux.

[0029] During specific application, after the temperature of the varistor chip 1 continuously rises to the set temperature, the low-melting-point solid flux inside the thermal fuse 4 becomes molten and flows out of the thermal fuse 4, causing the thermal fuse 4 to return to a hollow shape. Under the action of air pressure and surface tension, the thermal fuse 4 shrinks and deforms towards its hollow structure, so that the thermal fuse 4 is disconnected from the first electrode layer 2 to form an open circuit, preventing the varistor chip 1 from continuously heating up and catching fire;

[0030] In addition, the melting point of the low-melting solder joint 8 is lower than the melting point of the low-melting-point solid flux inside the thermal fuse 4, and the low-melting solder joint 8 and the thermal fuse 4 form a eutectic point at low temperature, thereby improving the thermal fuse response speed of the thermal fuse 4.

[0031] In the above embodiment, the second pin 7 is fixedly connected to the insulating gasket 6 through a fixing glue.

[0032] During specific application, the material of the fixing glue is insulating silicone or polyamide, and it does not age after being resistant to temperature for a long time above 105°C. It is used to install and fix the second pin 7 and the insulating gasket 6, making the second pin 7 stable on the insulating gasket 6, not easy to age, and extending the service life of the surge protector.

[0033] In the above embodiments, an insulating encapsulation layer 10 is wrapped on the varistor chip 1, and the insulating encapsulation layer 10 wraps the first electrode layer 2, the second electrode layer 3, the thermal fuse 4, the low melting point solder joint 8 and the insulating gasket 6. The insulating encapsulation layer 10 also wraps the ends of the first lead 5, the second lead 7 and the third lead 9 on the varistor chip 1.

[0034] In specific applications, the material of the insulating encapsulation layer 10 is epoxy resin with a softening point less than 80 °C. The insulating encapsulation layer 10 is used to wrap the varistor chip 1, the first electrode layer 2, the second electrode layer 3, the thermal fuse 4, the first lead 5, the insulating gasket 6, the second lead 7, the low melting point solder joint 8 and the third lead 9, so as to achieve moisture and humidity protection and electrical insulation for the surge protector.

[0035] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A resin-encapsulated lightning surge protector with thermal fuse protection, characterized in that: It includes a varistor chip (1), a first electrode layer (2), a second electrode layer (3) and a thermal fuse (4). The first electrode layer (2) is fixedly placed at the upper end of the varistor chip (1), and the second electrode layer (3) is fixedly placed at the lower end of the varistor chip (1). A first lead (5) is fixedly arranged on the first electrode layer (2). An insulating gasket (6) is fixedly arranged on the first electrode layer (2). A second lead (7) is fixedly arranged on the insulating gasket (6). The thermal fuse (4) is fixedly placed on the insulating gasket (6). One end of the thermal fuse (4) is electrically connected to one end of the second lead (7). The other end of the second lead (7) extends and deviates from the varistor chip (1). The other end of the thermal fuse (4) is electrically connected to the first electrode layer (2) and one end of the first lead (5) through a low-melting-point solder joint (8). The other end of the first lead (5) extends and deviates from the varistor chip (1). A third lead (9) is fixedly arranged on the second electrode layer (3). One end of the third lead (9) is electrically connected to the second electrode layer (3). The other end of the third lead (9) extends and deviates from the varistor chip (1).

2. The resin-encapsulated lightning surge protector with thermal fuse protection according to claim 1, characterized in that: The thermal fuse (4) is of a hollow structure, and a low-melting-point solid flux is filled in the thermal fuse (4).

3. The resin-encapsulated lightning surge protector with thermal fuse protection according to claim 1, characterized in that: The second lead (7) is fixedly connected to the insulating gasket (6) through a fixing glue.

4. The resin-encapsulated lightning surge protector with thermal fuse protection according to claim 1, characterized in that: The varistor chip (1) is wrapped with an insulating encapsulation layer (10). The insulating encapsulation layer (10) wraps the first electrode layer (2), the second electrode layer (3), the thermal fuse (4), the low-melting-point solder joint (8) and the insulating gasket (6). The insulating encapsulation layer (10) also wraps the ends of the first lead (5), the second lead (7) and the third lead (9) on the varistor chip (1).

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