JPH0513205A - Overcurrent and overvoltage protective element - Google Patents

Abstract

PURPOSE:To simultaneously replace a fuse and a varistor and to reduce their mounting space. CONSTITUTION:A first electrode 7 and a second electrode 8 are formed on one face of a sheetlike varistor base 6 so as to be separated by a prescribed distance; a third electrode 9 is formed on the rear in a position faced with the second electrode 8. A fuse piece (a fusible body) 10 is connected across the first and second electrodes 7, 8. Since a varistor is constituted between the electrodes 8, 9 by this constitution, the fuse and the varistor are formed as an integrated element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent and overvoltage protection element, and more specifically, it is used in various electric appliances such as household air conditioners and heating appliances, and in particular fuses and varistors are integrated. The present invention relates to an overcurrent and overvoltage protection device.

[0002]

2. Description of the Related Art FIG. 7 is an explanatory view of a conventional example.
Is a fuse, 2 is a varistor, 3 is a power plug, and 4 is a device body.

Conventionally, for example, in a home air conditioner or a heating device, there is a device used at AC100V, and an AC2
Some equipment used at 00V. As described above, when a large number of electric devices having different operating voltages are used, a mistake may occur in connecting to a power source having a voltage higher than the operating voltage of the devices.

For example, if a device whose operating voltage is AC100V (or 200V) is mistakenly set to AC200V (or 4),
If it is connected to a power source of 00V), the device may be damaged or burned.

In order to prevent such an accident, the electric equipment as described above has the structure shown in FIG. That is, the fuse 1 for overcurrent protection and the varistor 2 for overvoltage protection were provided between the device body 4 and the plug 3 for power supply.

Since the electric device of this structure can protect against overcurrent and overvoltage, even if a voltage higher than the originally used voltage is applied, only the fuse or varistor is damaged or burnt out, and the device body 4 It is possible to prevent damage and burnout accident.

[0007]

SUMMARY OF THE INVENTION The above-mentioned conventional devices have the following problems. (1) For example, when an overcurrent flows in an electric device or an overvoltage is applied, the varistor causes a large current to flow to the ground side, and the fuse or varistor is burned or destroyed. In such a case, it is necessary to replace the fuse or varistor with a new one.

By the way, in a normal case, when the fuse is burned due to an overcurrent, the varistor is often deteriorated. Therefore, it is necessary to replace the varistor with a new one when replacing the fuse.

However, since the fuse and the varistor are separate parts, the fuse may be replaced with a new one and the varistor may be forgotten. In such a case, since the deteriorated varistor is used, deterioration of the varistor gradually progresses, and eventually thermal runaway may occur, leading to a burnout accident of the device body.

(2) The fuse and the varistor are separate parts, and their mounting locations are also different. Therefore, the required space becomes large, which has been an obstacle to miniaturization of electric devices. The present invention solves such conventional problems and enables replacement of a fuse and a varistor at the same time,
The purpose is to reduce the installation space.

[0011]

FIG. 1 is a principle view of the present invention, and FIG. 1A is a sectional view of an overcurrent and overvoltage protection element, and FIG. 1B.
Is an equivalent circuit of the element. In the figure, the same symbols as those in FIG. 7 indicate the same components. Further, 5 is an overcurrent overvoltage protection element, 6
Is a varistor element body, 7 is a first electrode, 8 is a second electrode, 9
Indicates a third electrode.

(1) The first electrode 7 and the second electrode 8 are provided on one surface of the plate-shaped varistor element body 6 at a predetermined distance, and the second electrode is formed on the other surface of the varistor element body 6. The third electrode 9 is provided at a position facing the electrode 8 of FIG. 1 to form a varistor between the second and third electrodes 8 and 9, and further between the first and second electrodes 7 and 8. By connecting the fuse piece (fusible body) 10, the fuse and the varistor were integrated to form an overcurrent and overvoltage protection element.

(2) In the above structure (1), the fuse piece 1
0 is composed of a chip type fuse. (3) In the above configuration (1) or (2), a groove is provided in the varistor element body 6 located between the second electrode 8 and the third electrode 9. (4) Each of the electrodes 7, 8 of the above configuration (1), (2), or (3),
The lead wire was attached to each No. 9.

(5) In the above configuration (1), (2), or (3), both ends of the varistor element body 6 are covered with the ends of the varistor element body 6 and extend from the upper surface to the lower surface. , An end electrode is provided, and one end electrode is
By connecting the other end electrode to the second electrode 8 by connecting the other end electrode to the electrode 7, the surface mounting element was obtained.

[0015]

The operation of the present invention based on the above construction will be described with reference to FIG. In the device shown in FIG. 1A, the first
1B, the position of the second electrode 8 is b, and the position of the third electrode 9 is c, the equivalent circuit of the overcurrent overvoltage protection element 5 is as shown in FIG. 1B.

As shown, a fuse 1 is placed between a and b.
Is connected, and the varistor 2 is connected between b and c to form an equivalent circuit. By doing so, an element in which the fuse and the varistor are integrated can be obtained.

When this element is used in a device that requires a fuse and a varistor, one element can provide overcurrent protection and overvoltage protection, and when the element 5 burns out or is destroyed, the fuse and varistor are also included. Can be exchanged at the same time. Further, by providing a groove in the element 5, the element 5
Can be downsized.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (Description of First Embodiment) FIGS. 2 and 3 are views showing a first embodiment of the present invention, FIG. 2 is a view showing an overcurrent overvoltage protection element, and FIG. 3 is a fuse piece (fusible body). ) Is an example.

In the figure, the same symbols as those in FIG. 1 indicate the same components.
Further, 11A, 11B and 11C are lead wires, 12 is a chip type fuse, 13 is an alumina substrate, and 14A and 14B are terminals.

First, the overcurrent and overvoltage protection device of the first embodiment will be described with reference to FIG. 2A is a plan view, FIG. 2B
FIG. 6 is a sectional view taken along line XY. As shown, one side of the plate-shaped varistor element body 6 is separated by a predetermined distance from the first side.
The electrode 7 and the second electrode 8 are provided. A third electrode 9 is provided on the other surface of the varistor element body 6 at a position facing the second electrode 8.

Since the second electrode 8 and the third electrode 9 are electrodes of the varistor, both electrodes have substantially the same size. Furthermore, between the first electrode 7 and the second electrode 8,
A fuse piece (fusible body) 10 is provided, and both ends of the fuse piece 10 are connected to the electrodes (7, 8) by soldering or the like.

The above first, second and third electrodes 7, 8, 9
Is formed of, for example, a thick film conductor (formed by printing). The lead wires 11A and 1A are respectively connected to the electrodes 7, 8 and 9.
1B and 11C are connected by soldering or the like.

In this way, the second and third electrodes 8,
A varistor is formed between the electrodes 9, and the fuse piece 10 is provided between the second electrode 8 and the first electrode 7, which is one of the electrodes.
Is connected, so that the fuse and the varistor are connected. Next, a specific example of the fuse piece (fusible body) will be described with reference to FIG. 3A shows a chip type, FIG. 3B shows a plate type, and FIG. 3C shows a linear type.

The chip type fuse 12 is an alumina substrate 1.
The fuse piece 10 is provided on the alumina substrate 3, and the terminals 14A and 14B are provided at both ends of the alumina substrate 13. When the chip-type fuse 12 is used in the device shown in FIG. 2, for example, the terminal 14A may be connected to the first electrode 7 and the terminal 14B may be connected to the second electrode 8.

The plate-shaped fuse piece is constructed as shown in FIG. 3B, and the linear fuse piece is shown in FIG. 3C.
It is configured as shown in. When these fuse pieces are used in the element shown in FIG. 2, one end of the fuse piece 10 may be connected to the first electrode 7 and the other end may be connected to the second electrode 8. In the case of the present embodiment, any of the above may be used as the fuse piece 10. It is also possible to use other fuse pieces.

(Explanation of the Second Embodiment) FIG. 4 is a view showing an overcurrent and overvoltage protection element of the second embodiment. FIG. 4A is a plan view and FIG. 4B is a sectional view taken along the line ST. In the figure, the same symbols as those in FIG. 2 indicate the same components. 16A and 16B indicate end electrodes.

The element of the second embodiment is an example of a surface mount type element. In this example, the first, second and third electrodes 7,
The arrangements of 8 and 9 and the fuse piece 10 are the same as in the first embodiment, but the configuration of the terminal portion is different.

As shown in the drawing, end electrodes 16A and 16B are provided at both ends of the varistor element body 6, the end electrode 16A is connected to the first electrode 7, and the end electrode 16B is connected to the second electrode 8. Connecting. However, the end electrode 16B and the third electrode 9 must be separated by a certain distance.

In this case, the end electrodes 16A and 16B are formed (printed) of, for example, thick film conductors. The first electrode 7
And the end electrode 16A, and the second electrode 8 and the end electrode 16B
May be formed continuously at the same time, but at this time, they are formed so as to cover the end portion of the varistor element body and extend from the upper surface to the lower surface.

When using this device, the end electrode 16
A and 16B are used as terminals on both ends, and the third electrode 9 is used as a terminal on the varistor side. For example, when the element is mounted on the motherboard, the end electrodes 16A, 16B and the third electrodes are formed on the wiring pattern on the motherboard.
The electrode 9 of is connected.

(Other Embodiments) The embodiments have been described above, but the present invention can be implemented as follows. Figure 5
6 is an overcurrent and overvoltage protection device of another embodiment (No. 1), FIG.
FIG. 6 is a diagram showing an overcurrent and overvoltage protection device (No. 2) of another embodiment. In the figure, the same symbols as those in FIGS. 2 to 4 indicate the same components. Moreover, 18 shows a groove.

Example 1 ... See FIG. 5 This example is a modification of the second embodiment shown in FIG. 4, and a groove 18 having a substantially semicircular cross section is formed in a part of the varistor element body 6. It was formed. The shape of the groove is not limited to a semicircular shape as long as it can increase the creepage distance.

This groove 18 is provided with the third electrode 9 and the end electrode 1.
6B and 6B. In this case, assuming that the thickness of the varistor element body 6 is d and the linear distance between the third electrode 9 and the end electrode 16B is x, the relationship of x> d is established when there is no groove between both electrodes. It is necessary to.

In this way, the creepage distance between the third and end electrodes can be increased, and the distance x can be made shorter than that of the second embodiment. Therefore, miniaturization of the element can be realized.

Example 2 ... See FIG. 6A This example is a modification of the example shown in FIG. 2 and is an example in which the fuse piece 10 is formed of a thick film (printing).

Example 3 ... See FIG. 6C This example is a modification of the example shown in FIG. 4, and is an example in which the fuse piece 10 is formed of a thick film (printing).

Example 4 The element 5 of each of the above examples is covered with an insulating resin. In this case, portions that will be external terminals (for example, lead wires 11A, 11B, 11C, end electrodes 16A, 1C)
Except for 6B and the third electrode 9), all other parts are covered with resin. [Example 5] For example, in the element shown in FIGS. 2 and 6B, the whole is molded with an insulating resin, and the lead wires 11A, 11
You may expose the front-end | tip part of B and 11C.

[0038]

As described above, the present invention has the following effects. (1) Since the fuse and varistor are integrated, the mounting space for them is reduced. Therefore, the size of the device can be reduced.

(2) Since the fuse and the varistor can be replaced at the same time, it is no longer necessary to replace the fuse and forget to replace the varistor as in the conventional case. Therefore, by using the deteriorated varistor, an accident such as burnout of the device can be prevented. (3) By providing a groove in the varistor element body, the size of the element can be further reduced.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a diagram showing an overcurrent and overvoltage protection device according to a first embodiment of the present invention.

FIG. 3 is a diagram showing an example of a fuse piece (fusible body).

FIG. 4 is a diagram showing an overcurrent and overvoltage protection device according to a second embodiment.

FIG. 5 is an overcurrent and overvoltage protection device according to another embodiment (No. 1).
It is the figure which showed.

FIG. 6 is an overcurrent and overvoltage protection device according to another embodiment (No. 2).
It is the figure which showed.

FIG. 7 is an explanatory diagram of a conventional example.

[Explanation of symbols]

5 Overcurrent overvoltage protection element 6 Barista body 7 First electrode 8 Second electrode 9 Third electrode

Claims (5)

[Claims] 1. A first electrode (7) and a second electrode (8) are provided on one side of a plate-shaped varistor element body (6) at a predetermined distance from each other, and at the same time, the varistor element body (6) is formed. On the other surface, a third electrode (9) is provided at a position facing the second electrode (8) to form a varistor between the second and third electrodes (8, 9). An overcurrent overvoltage protection element characterized in that a fuse and a varistor are integrated by connecting a fuse piece (fusible body) (10) between the first and second electrodes (7, 8). 2. A chip-type fuse (12) is used as the fuse piece (10).
The overcurrent and overvoltage protection device described. 3. A varistor element body (6) located between the second electrode (8) and the third electrode (9) is provided with a groove (1).
8) The overcurrent overvoltage protection device according to claim 1 or 2, further comprising: 4. The first, second and third electrodes (7,
8 and 9) to lead wires (11A, 11B, 11), respectively.
C) is attached, The overcurrent overvoltage protection element of Claim 1, 2 or 3 characterized by the above-mentioned. 5. End electrodes (16A, 16B) are provided at both ends of the varistor element body (6) so as to cover the ends of the varistor element body (6) and extend from the upper surface to the lower surface. By providing and connecting one end electrode (16A) to the first electrode (7) and the other end electrode (16B) to the second electrode (8), the surface mounting type 2. The device according to claim 1,
2. The overcurrent / overvoltage protection element according to 2 or 3.