JPH0453102A - Surge absorber with safety function - Google Patents

Abstract

PURPOSE:To avoid ignition of a varistor element and a circuit to be protected by a method wherein a low melting point metal element is melted by heat from the varistor element and separated by the shrinkage of a heat-shrinkable insulating tube and the heat shrinkable insulating tube which is an insulator isolates the separated parts of the low melting point metal element from each other. CONSTITUTION:A surge absorber is composed of a varistor element which has an inner surface having a coaxial cylindrical shape and has an electrode on its outer surface, a low melting point metal element connected electrically to the electrode on the outer surface in series and heat-shrinkable insulating tubes 28 which cover the varistor element so as to prevent the electrode on the outer surface from electrical contact and which separate the low melting point metal element by its shrinkage. If a continuous overvoltage is applied, the varistor element 21 gradually generates heat and the heat is transmitted to a low melting point metal element 25 through the heat-conducting insulating layer 24 such as a glass layer to melt the element 25. At the same time, a plurality of the heat-shrinkable insulating tubes 38 and 38a are made to shrink and separate the melted low melting temperature metal element 25. The insulating tubes isolate the separated parts of the low melting temperature metal element 25 from each other to break an overcurrent applied to the varistor element without an arc discharge.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a surge absorber with a security function to protect equipment from surge voltage caused by lightning, etc. The present invention relates to a surge absorber with a security function, which includes a surge absorbing element and an element that interrupts overcurrent to prevent a protected circuit from igniting.

2. Description of the Related Art Conventionally, this type of surge absorber has rarely been constructed as shown in FIG. 6 (for example, there is a surge absorber as shown in Japanese Patent Application Laid-open No. 76551/1983). In Fig. 6, 1 is a disc-shaped surge absorbing element, 2& and 2
Denoted by b is an electrode provided on both sides of the electrode, and an elastic lead wire 3.4 is connected to the electrode 2a with a low melting point solder 5.
The lead wire 6 is connected to the electrode 2b with high melting point solder (not shown). Furthermore, the leads 3, 4.6 are connected to the support 7.
are connected and fixed to connection terminals 8, 9, and 10, respectively.

It is structured as above, and once it is absorbed (in the mind),
Below, I will explain about move A1. The world's birth control vessel is used as shown in Figure 7. 1 inch, that is, the connection end -
Connect terminals 8 and 9 to power supply 11, and connect terminal j! -9, 10 are connected to the protected circuit 12 t'-Zp =, ・A, and normally 4., ``connection end - f s + '' is short-circuited, connection end 8 is connected to the protected circuit 12.
, 9 has a high resistance and is close to open.
When a surge voltage occurs in the power supply line, the resistance of the absorption element T1 becomes low, and the connection and terminals 8 and 9 become almost short-circuited, and the surge current flows through the protected circuit 122. ] instead, it flows between the connecting ends J-8 and J-9 and absorbs +1-.

This I〒! In the l path, if a continuous overvoltage is applied to the power supply input, the continuous overcurrent = - diabsorption element:
``Flow 1 at 1, thermal absorption element 1 generates!'' 7, and low melting point solder 5 melts +71, Figure 8 shows the elasticity i.
' The lead acids 3 and 4 are separated from the voltage f12a as shown by the arrows, i+, -1,1- absorbing element R1 and the protected circuit 12.
is cut off from the power supply 11.

Problems to be solved by the invention in the M method In such a conventional configuration, when a continuous overcurrent flows through the surge absorber, the low melting point)... The wire is not connected i1: 'i'' (-) The electrode that was there also separates, but it is a large current (?) - Story 1. Between the electric rod and the wire Arc discharge occurs (-, 1. from overcurrent, 1.).
1. The problem is that the absorbing elements I can ignite without being able to do so. 5. The present invention solves these problems. The purpose is to completely block the absorption element -f. , Problems and Solutions for ∆kO Solving this Problem - ``To solve this problem, the present invention has a concentric cylindrical shape 17, an inner surface and a varimetal element body having electrodes on each side. , the electrodes on the outer surface of the lower body of the varistor are electrically connected to the +M row (-'r plate connection 77), the low melting point metal element, and the electrodes and the electrodes on the outer surface of the varistor body are connected to the L row.

The outer surface of the varistor element is covered with air so that the low-melting point metals', ij, and l elements adhere tightly to the outer surface of the varistor element. Due to the heat generation of Rinuta's body, ・"te-contraction L1. J',',”,,,
It consists of a heat-shrinkable insulating material that fuses the low melting point metal element. In this configuration, if a continuous overvoltage is applied to the security device T1 thermal absorber, a continuous overcurrent will flow to the varistor body, causing the above-mentioned varistor accumulation. Body heat generation [2. Due to the heat of the body>1 low melting point metal element melts,
Then, by shrinking the heat-shrinkable insulating tube 1,
- The low melting point metal element is melted, and the overcurrent is completely cut off by the heat-shrinkable insulating duplex with an insulator and (5') thick heat-shrinkable insulation duplex. ,1
Prevents ignition of the varistor body and initial protection circuit.
can be done. 2 Embodiments Below, embodiments of the present invention will be explained with reference to the drawings.71. , FIG. 1 shows the security function according to the first embodiment of the present invention.
1 is a top view showing the structure of the surge absorber, and Fig. 2-1 is a perspective view showing the structure of the surge absorber. In Fig. 2, 21 is a concentric cylindrical 17 varistor, 22.2
22L is the outer surface of the varistor body 21.

The picture electrodes 22. of the varistor body 21 are connected to the electrodes 23, 23 and 2sai, and the j connection lead wires provided on the inner surface. , 22a. Reference numeral 24 is an insulating material made of an inorganic, non-metallic material such as glass, and coats the entire (or part) of the surface of the varistor body 210. , 25 is a low melting point metal element 7, such as a eutectic solder wire made of tin or lead.One end of this low melting point metal element 2b and the connecting lead wire 23 are connected to each other by caulking 26, for example.
The other end of the low-melting point metal element 26 and the connecting lead wire 27 are connected by, for example, a caulking 26a. A heat-shrinkable insulating duplex whose circumference shrinks to be smaller than the outer circumference of the varistor element body 21 is used so that the surface of the insulator 240 that is collapsing on the surface of the varistor element body 21 and the low melting point metal element 25 are in close contact with each other. Cover us and fix L -1" 1, 1
No: 1. The product of the present invention is a low melting point metal when melting! −′element 2
6. Shatterproof and moisture-proof effect? ], the connecting lead wires 23, 23&, 27 may be cased with an insulating resin or the like so that the 9-5 ends of the wires 23 and 27 are left open, and at least the area around the low melting point metal element 25 is hollow. There are many, but
These are not shown in FIGS. 1 and 2.

The operation of the surge absorber with security function configured as described above will be explained below. Here, this surge absorber with safety function is used as shown in FIG. In Fig. 3, 29 is a power supply or signal source, which is connected to the connection leads 23a and 27 of the surge absorber with safety function, and 3o is a protected circuit, which is connected to the connection leads 23, 23&. . Normally, there is a short circuit between the connection lead wire 23 and the connection lead wire 27, and a high resistance state between the connection lead wire 23 and the connection lead wire 23m, which is close to an open state. Now, if a surge voltage occurs in the power supply line or signal line, the varistor element body 21 will have low resistance, and the connection lead wire 23 and the connection lead wire 23 & will be in a state close to short circuit, and the surge current will be The surge does not flow through the circuit 30 but flows between the connection lead wire 23 and the connection lead wire 231L, and the surge is absorbed.

In this circuit, when a continuous overvoltage is applied to the power supply line or signal line due to contact with high voltage lines, a continuous overcurrent flows to the varistor body 21, and the varistor body 21
gradually generates heat, and this heat is transferred to the low melting point metal element 25 by the insulator 24, such as glass, which has good thermal conductivity.
The low melting point metal element 25 melts. At the same time, the heat-shrinkable insulating tube 28 contracts in the radial direction, and the molten low-melting point metal element 25 spreads in the radial direction of the heat-shrinkable insulating tube 28 -\
The low melting point metal element 25 is pushed out by the contraction force of
is separated into two parts with a heat-shrinkable insulating tube 28 in between. In other words, the overcurrent flowing through the varistor body 21 is completely eliminated without arc discharge after the low melting point metal element 25 is separated by the intervention of the heat-shrinkable insulating tube 28, which is an insulator, into the low melting point metal element 25. is blocked by. Therefore, the varistor body 21 stops generating heat, and ignition can be prevented.

As described above, the surge absorber with security function of this embodiment has the effect of preventing the varistor element body 21 and the protected circuit 30 from igniting due to continuous overvoltage.

Next, a second embodiment of the present invention will be explained with reference to FIGS. 4 and 5. FIG. 4 is a front view showing the structure of a surge absorber with a security function according to a second embodiment of the present invention, and FIG. 5 is a perspective view showing the structure of a surge absorber with a security function according to the second embodiment. It is. The difference from the first embodiment is that heat-shrinkable insulating tubes are provided at two locations at a predetermined interval. In Figures 4 and 5, 3
1 is a concentric cylindrical varistor body; 32 and 321 are electrodes provided on the outer and inner surfaces of the varistor body 31; 33 and 331L are connecting lead wires; connected directly to. Reference numeral 34 is an insulator made of an inorganic non-metallic material such as glass, and coats the entire (or part) of the surface of the varistor body 31. Reference numeral 35 is a low melting point metal element such as a eutectic solder wire of tin or lead, and one end of this low melting point metal element 35 and the connection lead wire 33 are connected, for example, by caulking 36, and the low melting point metal element 35 is The other end and the connecting lead wire 37 are connected to each other by, for example, caulking 36a. 38. 38a is a heat-shrinkable insulating tube whose inner periphery shrinks to a smaller size than the outer periphery of the varistor body 31 due to heat, and the tube 38a is a heat-shrinkable insulating tube whose inner periphery shrinks to a smaller size than the outer periphery of the varistor body 31. 35
They are covered and fixed at predetermined intervals so that they are in close contact with each other.

The function of the surge absorber with security function configured in this way is similar to that of the first embodiment, but compared to the first embodiment, the heat-shrinkable insulating tube is fixed at two locations, so the Since the melting point metal element has two fusing points, the insulation distance becomes longer, and continuous overcurrent can be more reliably interrupted. Further, it is possible to reduce the variation in time until melting occurs.

In the examples of the present invention, glass, which is one of the inorganic and nonmetallic materials, was used as the insulator coating the surface of the varistor body, but the insulator is not limited to this. In addition, a eutectic wire of tin and lead was used as a low melting point metal element, but the low melting point metal element is not limited to this.Furthermore, a heat shrink tube was used in one or two places. Although it is fixed, it goes without saying that the number of fixing points is not limited.

However, in the embodiment of the present invention, the entire (or part) surface of the varistor body is coated with an insulating material, and the surface of the insulating material is in close contact with the low melting point metal element. It is also possible to omit this element and have a structure in which a portion of the outer surface of the varistor body without electrodes and a low melting point metal element are directly in close contact with each other. However, in this case, it is necessary to make the gap between the electrode on the outer surface of the varistor body and the low-melting point metal element wider than in the case of a configuration in which an insulator is interposed, and therefore the electrode area must be made smaller. Therefore, it is necessary to pay attention to the fact that the characteristics such as the amount of surge tilt are low.

Effects of the Invention According to the present invention, as described in 1-4, the varistor element body has a concentric cylindrical shape and has electrodes on the inner and outer surfaces, respectively;
A low melting point metal element electrically connected in parallel with the electrode of the varistor element on the 1st side of the varistor body; The outer surface of the varistor element body and the low melting point metal element are sifted so that they are in close contact with each other to prevent connection, and the heat that causes the varistor element body to shrink due to heat generated by the varistor element body and melt and melt the low melting point metal element The structure of the varistor element and the circuit to be protected can be effectively prevented from igniting due to continuous overvoltage.

[Brief explanation of the drawing]

Fig. 1 is an iE view showing the structure of the first embodiment of the surge absorber with security function according to the present invention, Fig. 2 is a perspective view showing the structure according to the same embodiment, and Fig. 3 is the same implementation. 4 is a front view showing a structure according to a second embodiment of the present invention, FIG. 6 is a perspective view showing a structure according to the same embodiment, and FIG. 6 is a conventional surge absorber. FIG. 7 is a circuit diagram showing an example of the use of the surge absorber, and FIG. 8 is a front view showing the surge absorber in operation. 21.31 ... Ballista element body, 22, 22a. 32.32a... Electrode, 24.34... Insulator, 26.3.5... Low melting point metal element, 28,
38. 381! L: Heat shrinkable insulation tube. Name of agent: Patent attorney Shigemu Awano and 1 other person//
Barista Sorin

Claims (3)

[Claims] (1) A varistor element having a concentric cylindrical shape and having electrodes on its inner and outer surfaces, a low melting point metal element electrically connected in series with the electrodes on the outer surface of the varistor element, and the varistor element. Covering the varistor body so that the outer surface of the varistor body and the low melting point metal element are in close contact with each other so as not to be electrically connected to the electrodes provided on the outer surface of the body;
A surge absorber with a security function includes a heat-shrinkable insulating tube that contracts due to heat generated by the varistor body and melts the low-melting point metal element. (2) The surge absorber with a security function according to claim 1, wherein the varistor body has a part or all of its surface coated with an insulating material. (3) The surge absorber with a security function according to claim 1, wherein two or more heat-shrinkable insulating tubes are provided at a predetermined interval.