Thermal protection type piezoresistor

Abstract

The utility model discloses a thermal protection type piezoresistor which comprises a piezoresistor body, the two sides of the piezoresistor body are electrically connected with a first wire pin and a second wire pin respectively, and one side of the piezoresistor body is further connected with a third wire pin. The third lead pin is electrically connected with the second lead pin through a thermal fuse, and the thermal fuse is of a tubular structure. According to the thermal protection type piezoresistor, compared with a hard shell design, the overall size and the shell cost are reduced; and compared with an explosion-proof coating design, the risk that the coating bursts after the thermal fuse is subjected to high-temperature hot melting is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of varistors, in particular to a thermal protection type varistor. Background Technique

[0002] Varistors are one of the commonly used components in electronic circuits and are used to prevent other components from being damaged by overvoltage. When an electronic circuit is affected by too much overvoltage, the varistor may malfunction and its performance may decline. Seriously, the varistor may break down or burn itself, which may cause damage to other surrounding components. In the current technology, there is a varistor with thermal protection function, usually with a thermal fuse attached in the current loop. The thermal fuse is close to the varistor component. When the current in the circuit is too large and causes high temperature, the thermal fuse will melt and break to achieve open circuit protection to prevent overheating damage. In order to more effectively protect the varistor from breakdown or burning, the most common method is to add a protective housing outside, but this will increase the cost. Therefore, subsequently, an explosion-proof coating is used to replace the protective housing. As the temperature of the varistor increases, the flux of the thermal fuse will vaporize, and seriously, the explosion-proof coating will be broken by these gases. Content of the Utility Model

[0003] The technical problem to be solved by the utility model is: to solve the problems existing in the above background technique, a thermal protection type varistor is provided, which reduces the overall volume and housing cost compared with the hard shell design; compared with the explosion-proof coating design, it avoids the risk of coating explosion after the thermal fuse is melted by high temperature.

[0004] The technical solution adopted by the utility model to solve its technical problems is: a thermal protection type varistor, including a varistor body, with a first wire pin and a second wire pin electrically connected to both sides of the varistor body respectively. A third wire pin is also connected to one side of the varistor body. The third wire pin and the second wire pin are electrically connected through a thermal fuse, and the thermal fuse is a tubular structure.

[0005] Further specifically defined, in the above technical solution, an insulating gasket is provided on one side of the varistor body, and the third wire pin is connected to the insulating gasket.

[0006] Further specifically defined, in the above technical solution, an insulating sleeve is provided outside the thermal fuse.

[0007] Further specifically defined, in the above technical solution, the thermal fuse is an integrally formed structure or a press-formed structure.

[0008] Further specifically defined, in the above technical solution, the thermal fuse is cylindrical, square columnar, hollow columnar or spring-shaped.

[0009] More specifically defined, in the above technical solution, the hot melt wire has a neck region with a reduced inner diameter.

[0010] More specifically defined, in the above technical solution, the hollow accommodation space of the tubular structure of the hot melt wire contains a soldering flux.

[0011] More specifically defined, in the above technical solution, the hot melt wire is in a spring shape. One end of the hot melt wire is welded to the second wire pin, and the other end is welded to the third wire pin. When any one of the welding points at both ends of the hot melt wire is disconnected or the wire is broken in the middle, the hot melt wire quickly breaks through the elastic force.

[0012] More specifically defined, in the above technical solution, the insulating sleeve has an accommodation space for the hot melt wire to slide.

[0013] The beneficial effects of the present utility model are as follows: The thermal protection type varistor provided by the present utility model has a tubular hot melt wire, which reduces the overall volume and the cost of the outer shell compared with the hard shell design; compared with the explosion-proof coating design, it avoids the risk of coating explosion after the hot melt wire is melted at high temperature. Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0015] Figure 1 is a structural schematic diagram of the present utility model;

[0016] Figure 2 is a structural schematic of the hot melt wire Figure 1 ;

[0017] Figure 3 is a structural schematic of the hot melt wire Figure 2 ;

[0018] Figure 4 is a structural schematic of the hot melt wire Figure 3 。

[0019] The reference numerals in the drawings are: 1, varistor body; 2, first wire pin; 3, second wire pin; 4, hot melt wire; 41, neck region; 5, third wire pin; 6, insulating gasket. Detailed Embodiments

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0021] In the description of the present utility model, it should be understood that the orientation or positional relationships indicated by the terms "one side", "the other side", "both sides", "between", "middle part", "upper end", "lower end", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0022] In the description of the present utility model, it should be noted that unless otherwise clearly specified and limited, the terms "set" and "connect" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0023] See Figures 1 to 4 , the thermal protection type varistor of the present utility model includes a varistor body 1. A first wire pin 2 and a second wire pin 3 are electrically connected to both sides of the varistor body 1 respectively. Specifically, the varistor body 1 is welded to the first wire pin 2, and the varistor body 1 is welded to the second wire pin 3. A third wire pin 5 is further connected to one side of the varistor body 1. Specifically, an insulating gasket 6 is provided on one side of the varistor body 1, and the third wire pin 5 is connected to the insulating gasket 6. The third wire pin 5 and the second wire pin 3 are electrically connected through a heat fuse 4, and the heat fuse 4 is a tubular structure. The hollow accommodating space of the tubular structure of the heat fuse 4 has a soldering flux. Since the tubular shape of the heat fuse 4 has a hollow accommodating space, it can ensure that when the heat fuse is melted at high temperature, there is enough internal cohesive flow space and the molten heat fuse will not overflow. That is, when the heat fuse 4 is in a tubular shape, the molten liquid will have enough internal cohesion and flow space.

[0024] Specifically, the thermal protection type varistor includes a varistor body 1, a first wire pin 2 and a second wire pin 3 electrically connected to both sides of the varistor body 1 respectively, an insulating gasket 6 provided on one side of the varistor body 1, and a third wire pin 5 electrically connected to the second wire pin 3 through a thermal fuse 4 on the insulating gasket 6. Preferably, the thermal fuse 4 is in a tubular shape. The composition of the thermal fuse 4 is: tin-silver-copper ternary eutectic point at 217°C; 96.5 / 3.5 tin-silver, by weight, eutectic point at 221°C and 99.3 / 0.7 tin-copper eutectic point at 227°C. The thermal fuse 4 has a neck region 41 with a reduced inner diameter. Specifically, the tubular thermal fuse 4 has a neck region 41 with a reduced inner diameter. When heated and shrunk inward, this neck region 41 melts and breaks faster, which can accelerate the reaction time.

[0025] Wherein, an insulating sleeve is provided outside the thermal fuse 4. Adding an additional insulating sleeve outside the thermal fuse 4 can provide an extra layer of protection. Specifically, an insulating sleeve can be sleeved outside the thermal fuse 4. The insulating sleeve can be made of inorganic materials, such as: ceramic materials, or plastics, such as thermoplastic sleeves, and the sleeve can further have heat shrinkability. The hollow accommodation space of the tubular structure of the thermal fuse 4 has a soldering flux. Specifically, the tubular thermal fuse 4 has a cavity, and this cavity has an accommodation space, and a soldering flux, such as: rosin, can be filled in this accommodation space. The thermal fuse 4 is an integrally formed structure or a compression-molded structure. For example: the integrally formed structure is by wire drawing, and the compression-molded structure is in a sheet-like curled shape. The thermal fuse 4 is a cylindrical, square-columnar or other shaped hollow column. For example: the hollow column is in a spring shape.

[0026] Of course, the thermal protection type varistor can also be designed into other structures. For example: the thermal fuse 4 is designed in a spring shape and arranged in the accommodation space of the insulating sleeve. The thermal fuse 4 is in a spring shape. One end of the thermal fuse 4 is welded to the second wire pin 3, and the other end of the thermal fuse 4 is welded to the third wire pin 5. When any one of the welding points at both ends of the thermal fuse 4 is disconnected or disconnected from the middle, the thermal fuse 4 quickly disconnects through the elastic force. The insulating sleeve has an accommodation space for the thermal fuse 4 to slide. That is to say, the two end points of the spring-shaped thermal fuse 4 are welded to the pins, and the temperatures of the two welding points can be different. When one of the welding points is disconnected, it can be disconnected through the elastic force of the spring. If the thermal fuse 4 is disconnected from the middle, it can also be quickly disconnected through the elastic force, and through the accommodation space of the insulating sleeve, the spring-shaped thermal fuse 4 has a sliding space.

[0027] For this thermal protection type varistor, the thermal fuse 4 is in a tubular shape. Compared with the hard shell design, it reduces the overall volume and the cost of the shell; compared with the explosion-proof coating design, it avoids the risk of coating bursting after the thermal fuse is melted at high temperature.

[0028] The above are only the preferred specific embodiments of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model, according to the technical solution of the present utility model and its inventive concept, making equivalent substitutions or changes should be covered within the protection scope of the present utility model.

Claims

1. A thermally protected varistor, characterized in that: It includes a varistor body (1), with a first wire pin (2) and a second wire pin (3) electrically connected to both sides of the varistor body (1) respectively. A third wire pin (5) is also connected to one side of the varistor body (1). The third wire pin (5) is electrically connected to the second wire pin (3) through a heat fuse (4), and the heat fuse (4) is a tubular structure.

2. The thermally protected varistor according to claim 1, wherein: An insulating gasket (6) is arranged on one side of the varistor body (1), and the third wire pin (5) is connected to the insulating gasket (6).

3. The thermally protected varistor according to claim 1, characterized in that: An insulating sleeve is arranged outside the heat fuse (4).

4. The thermally protected varistor according to claim 1, characterized in that: The heat fuse (4) is an integrally formed structure or a compression-molded structure.

5. The thermally protected varistor according to claim 1, wherein: The heat fuse (4) is cylindrical, square-columnar, hollow-columnar or spring-shaped.

6. The thermal protection type varistor according to claim 1, wherein: The heat fuse (4) has a neck region (41) with a reduced inner diameter.

7. The thermally protected varistor according to claim 1, characterized in that: The hollow accommodation space of the tubular structure of the heat fuse (4) has a soldering flux.

8. The thermally protected varistor according to claim 5, characterized in that: The heat fuse (4) is spring-shaped. One end of the heat fuse (4) is welded to the second wire pin (3), and the other end of the heat fuse (4) is welded to the third wire pin (5). When any one of the welding points at both ends of the heat fuse (4) is disconnected or it is disconnected from the middle, the heat fuse (4) quickly disconnects through elastic force.

9. The thermally protected varistor according to claim 3, wherein: The insulating sleeve has an accommodation space for the heat fuse (4) to slide.

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