CN100361237C - A piezoresistor with arc extinguishing and flame retardant function - Google Patents

Abstract

The invention relates to a piezoresistor. The piezoresistor has a housing and a piezoresistor main body enclosed in the housing. There is a gap between the inner wall of the housing and the outer wall of the piezoresistor main body to form an accommodation cavity. The cavity is filled with insulating non-combustible fibers and constitutes an insulating non-combustible fiber layer wrapping the main body of the piezoresistor. The insulating non-combustible fiber of this product is more convenient to fill and seal into the shell, so that the processing of the product is more convenient. The insulating non-combustible fiber layer adopted in the present invention has better flexibility, and has a stronger ability to absorb bursting kinetic energy, and can play a better buffering role, which is beneficial to ensure that the shell is not damaged.

Description

A piezoresistor with arc extinguishing and flame retardant function

technical field

The invention relates to a piezoresistor.

Background technique

As a surge protection component, varistors are widely used in various electronic devices. During use, it is found that when the external surge energy exceeds the withstand capacity of the varistors, the varistors will be broken down and short-circuited. In the actual circuit, the varistor is often connected between the live line and the neutral line of the power supply. When a short circuit occurs, the instantaneous energy is very large, and local high temperature will be generated at the breakdown damage, which may wrap the outside of the varistor ceramic substrate. The insulating and moisture-proof wrapping layer (usually made of organic materials such as epoxy resin as the main material) ignites, and in severe cases, it may cause fires in electrical equipment such as air conditioners.

In response to this potential safety hazard, some technical measures have been used to prevent the occurrence of fire accidents. For example, the applicant once disclosed a piezoresistor with an arc-extinguishing and flame-retardant function in Chinese utility model patent ZL200420033754.9. The main body of the varistor, the main body of the varistor is composed of a varistor ceramic substrate and an insulating coating layer encapsulating the varistor ceramic substrate, and two separate internal electrodes are arranged on the surface of the varistor ceramic substrate , a first lead-out electrode and a second lead-out electrode are connected to the main body of the varistor, and one end of the first lead-out electrode and the second lead-out electrode is respectively conductively connected to two internal electrodes on the surface of the varistor ceramic substrate, The other ends of the first lead-out electrode and the second lead-out electrode pass through the insulating encapsulation layer and extend to the outside of the insulating housing, which is characterized in that there is a gap between the inner wall of the insulating housing and the outer wall of the piezoresistor body And a closed powder containing chamber is formed, and the insulating non-combustible powder is filled in the powder containing chamber to form an insulating non-combustible powder layer wrapping the main body of the piezoresistor. The technical solution given by this patent is extremely simple but effective. It solves the long-standing technical problems in the field of piezoresistor manufacturing. The manufacturing cost of the product does not increase much, and it can effectively prevent electrical damage caused by arc discharge. Combustion accidents can be avoided, and the transfer of high heat to the shell can be alleviated, and the damage caused by the bursting of the ceramic body can be reduced, and users can also easily make it match with existing circuit boards. In addition, in the above-mentioned patent, a further improvement scheme of setting air holes on the shell wall of the shell is also given, so as to release the high-heat gas generated in the shell in time when the piezoresistor breaks down and short-circuits, so that even if a thinner or The lower-strength housing can also prevent the housing from bursting when the piezoresistor is broken down and short-circuited, thereby helping to reduce the production cost of the product.

Although the technical solution given by the above-mentioned patent has many advantages, recent studies have shown that the technical solution of the above-mentioned patent can also be optimized, so as to further avoid the damage caused by the explosion of the porcelain body and simplify the structure of the product. Accordingly, the production process of the product is simplified, and the production cost of the product is reduced.

Contents of the invention

The object of the present invention is to improve the structure of the above-mentioned existing piezoresistor, so as to further avoid the damage caused by the bursting of the ceramic body and simplify the structure of the product.

The varistor of the present invention has a housing and a varistor main body accommodated in the housing. The varistor main body is composed of a varistor ceramic substrate and an insulating coating layer encapsulating the varistor ceramic substrate. The surface of the pressure-sensitive ceramic substrate is provided with two separated internal electrodes, and the first lead-out electrode and the second lead-out electrode are connected to the main body of the varistor, one end of the first lead-out electrode and the second lead-out electrode One end is conductively connected to two internal electrodes on the surface of the pressure-sensitive ceramic substrate respectively, the other end of the first lead-out electrode and the other end of the second lead-out electrode pass through the insulating encapsulation layer and extend out of the housing, There is a gap between the inner wall of the housing and the outer wall of the piezoresistor main body to form an accommodating chamber, which is characterized in that the accommodating chamber is filled with insulating non-combustible fibers to form an insulating non-combustible fiber layer wrapping the main body of the varistor.

In the present invention, said insulating non-combustible fiber is a non-conductive and non-combustible fiber, such as common and cheap asbestos fiber or aluminum silicate fiber, alumina fiber, silica fiber, glass fiber, etc. fiber and more. The insulating non-combustible fiber can be in the form of filaments or flocs, and can also be an insulating non-combustible fiber fabric woven into a net or other shapes.

In addition, in the present invention, an exhaust port can also be provided on the shell wall of the housing, so as to release the high-heat gas generated in the housing when the varistor breaks down and short-circuits, so as to avoid as much as possible when the varistor breaks down and short-circuits. Explosion occurs, and with regard to the basic technical solution of the present invention, an exhaust port may not be provided on the shell wall of the housing, which is similar to the aforementioned existing products.

In the present invention, the insulating non-combustible powder layer in the aforementioned existing products is essentially replaced by the insulating non-combustible fiber layer. This substitution can produce the following positive effects:

1. When the varistor is short-circuited and broken down, sometimes the ceramic body will burst, and the hot ceramic body fragments will fly around, causing great damage. Compared with the insulating non-combustible powder layer, the insulating non-combustible fiber layer used in the present invention has better flexibility, its ability to absorb burst kinetic energy is stronger, and it can play a better buffering role, which is beneficial to ensure that the shell is not damaged .

2. After adopting the scheme of the present invention, the flexibility and mutual pulling shape of the insulating non-combustible fiber layer can also better prevent damage caused by flying fragments of the porcelain body.

3. When making products, silky, flocculent, and net-like insulating non-combustible fibers are easier to fill and seal into the shell than discrete insulating non-combustible powders, so that the processing of the product is more convenient.

4. When an exhaust port for releasing high-heat gas is provided on the casing, the shape and size of the exhaust port are no longer limited, which is also beneficial to the production of the product. In the present invention, it is even possible to directly adopt an open housing (this can be considered as having a large exhaust port on the housing), at this time, it is only necessary to bond or set a limiting structure (such as a limiting structure). Steps or limit protrusions) and other fixing methods are enough to fix the insulating non-combustible fiber layer in the housing so that it will not fall out of the housing. When making the aforementioned existing products, the aperture of the vent and the particle size of the powder in the insulating non-combustible powder layer must be properly selected so that the powder will neither leak from the vent nor block the vent.

Therefore, compared with the technical solutions given in the aforementioned existing patents, the technical solution of the present invention can further avoid the damage caused by the cracking of the porcelain body, and can simplify the structure of the product, correspondingly simplify the production process of the product, and reduce the production cost of the product. cost.

The content of the present invention is further described in conjunction with the following examples, but the content of the present invention is not limited to the content involved in the examples.

Description of drawings

FIG. 1 is a schematic structural diagram of a piezoresistor in Embodiment 1.

FIG. 2 is a cross-sectional view along line A--A of FIG. 1 .

Fig. 3 is a B--B sectional view of Fig. 1 .

Fig. 4 is a C--C sectional view of Fig. 1 .

FIG. 5 is a schematic structural diagram of the piezoresistor in Embodiment 2.

Fig. 6 is a D--D sectional view of Fig. 5 .

FIG. 7 is a schematic structural diagram of a piezoresistor in Embodiment 3.

FIG. 8 is a sectional view along E-E of FIG. 7 .

Detailed ways

Embodiment 1: As shown in Figures 1 to 4, the varistor in this embodiment has a housing 1 and a varistor main body 2 contained in the housing, and the varistor main body 2 is made of a varistor ceramic substrate 3 and the insulating coating layer 4 that wraps the pressure-sensitive ceramic substrate 3, two separate internal electrodes 5, 6 are arranged on the surface of the pressure-sensitive ceramic substrate 3, and are connected to the main body of the varistor 2 There are a first lead-out electrode 7 and a second lead-out electrode 8, one end of the first lead-out electrode 7 and one end of the second lead-out electrode 8 respectively conduct electricity with the two internal electrodes 5, 6 on the surface of the pressure-sensitive ceramic substrate 3 connection, the other end of the first lead-out electrode 7 and the other end of the second lead-out electrode 8 pass through the insulating encapsulation layer 4 and extend out of the housing 1, the inner wall of the housing 1 is connected to the varistor main body 2 There is a gap between the outer walls of the outer walls and constitutes an accommodating cavity, which is characterized in that the accommodating cavity is filled with insulating non-combustible fibers to form an insulating non-combustible fiber layer 9 that wraps the varistor main body 2 .

In this embodiment, the insulating non-combustible fiber layer 9 is an asbestos fiber layer. The adopted asbestos fiber layer has the advantages of low price, good flame retardant effect, dense and flexible fiber layer, and stronger ability to absorb bursting kinetic energy.

Embodiment 2: As shown in Figures 5 and 6, the piezoresistor in this embodiment is similar to that of Embodiment 1, the difference is that in this embodiment, a cavity is provided on the housing 1 so that the housing cavity is connected to the outside of the housing 1. connected exhaust port 10. In order to release the high-heat gas generated in the casing 1 as soon as possible when the piezoresistor is broken down and short-circuited. In addition, the insulating non-combustible fiber layer 9 used is an aluminum silicate fiber layer.

Embodiment 3: As shown in Figures 7 and 8, the piezoresistor in this embodiment is similar to that of Embodiment 2, that is, the housing 1 is still provided with an exhaust port that communicates the housing chamber with the outside of the housing 1 10. The difference is that in this embodiment, a casing with an open top is directly used, and the opening at the top of the casing can be regarded as a large exhaust port 10 opened on the casing.

In this embodiment, the insulating non-combustible fiber layer 9 can be fixed in the casing 1 by setting the limiting flange 11 on the upper edge of the open inner wall, so that it will not come out of the casing 1 .

Of course, the insulating non-combustible fiber layer can also be fixed in the casing by bonding or setting other limiting structures (such as limiting steps or limiting protrusions) and other fixing methods.

As far as the present utility model is concerned, the above-mentioned exhaust port 10 can also be opened in the rest of the housing 1, thus constituting a new embodiment.

Claims (4)

1. A varistor with arc extinguishing and flame retardant function, which has a housing and a varistor main body contained in the housing. The varistor main body is composed of a varistor ceramic substrate and a varistor ceramic substrate wrapped It is composed of an insulating coating layer sealed, two separate internal electrodes are arranged on the surface of the varistor ceramic substrate, and a first lead-out electrode and a second lead-out electrode are connected to the main body of the varistor, and the first lead-out electrode One end of the electrode and one end of the second lead-out electrode are electrically connected to the two internal electrodes on the surface of the pressure-sensitive ceramic substrate respectively, and the other end of the first lead-out electrode and the other end of the second lead-out electrode pass through the insulating envelope layer and extend to the outside of the shell, there is a gap between the inner wall of the shell and the outer wall of the piezoresistor body to form a housing chamber, which is characterized in that the housing chamber is filled with insulating non-combustible fibers and constitutes a pressure-sensitive Insulating non-combustible fiber layer wrapped around the body of the resistor. 2. The piezoresistor according to claim 1, characterized in that an exhaust port is opened on the housing to connect the accommodating cavity with the outside of the housing. 3. The varistor according to claim 1 or 2, characterized in that the insulating non-combustible fiber layer is an asbestos fiber layer. 4. The varistor according to claim 1 or 2, characterized in that the insulating non-combustible fiber layer is an aluminum silicate fiber layer.

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