JPH0733354Y2 - Fuse resistor - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse resistor for cutting off an excessive current flowing through various devices to protect circuit components, and particularly to prevent an arc discharge through the excessive current when the overcurrent is cut off. The present invention relates to a fuse resistor capable of preventing and surely interrupting an excessive current.

[0002]

2. Description of the Related Art Conventionally, a wire or plate-shaped current fuse made of an alloy of lead, tin or the like has been used as a safety mechanism for protecting circuit components in various devices from excessive voltage. A current exceeding the specified value flows and melts, thereby interrupting the current.

[0003]

However, in the above-described conventional current fuse, in addition to the fact that the fusing characteristics are likely to vary depending on the surrounding conditions, when an excessive voltage is applied across the fused fuse, In some cases, an arc discharge is generated between the ends of the blown fuse, and the overcurrent cannot be interrupted. Further, once this arc discharge is generated, it is difficult to extinguish the arc because the discharge sustaining voltage is low, and further carbon dioxide and the like in the atmospheric components are electrolyzed by the arc discharge and carbon having good conductivity is scattered around,
It also adheres to the vicinity of the ends of the cut fuses to deteriorate the insulation resistance.

Therefore, there exists a current fuse in which arc extinguishing powder such as ceramic powder for preventing generation of arc discharge is enclosed in a glass tube together with a fuse. However, although the current fuse containing the arc-extinguishing powder can certainly prevent the generation of arc discharge, the arc-extinguishing powder does not generate the heat generated in the fuse when an overcurrent to be blown flows. There is a problem in that it escapes to the outside due to conduction, which makes it impossible to obtain desired fusing characteristics.

Therefore, it is conceivable to use arc-extinguishing gas instead of the arc-extinguishing powder having heat conductivity, but it is necessary to seal the container in an airtight state in order to enclose the arc-extinguishing gas. As such a sealing material, low melting point glass, silver solder, solder, etc. are usually melted and used. However, since the fused sealing materials are all at high temperature, the fuse itself in the container may be fused by this heat.

The present invention has been devised in view of the above-mentioned points, and does not generate an arc discharge when an overcurrent is interrupted,
Moreover, it is an object of the present invention to realize a fuse resistor capable of reliably interrupting an overcurrent without changing a desired interrupting characteristic.

[0007]

In order to achieve the above-mentioned object, a fuse resistor of the present invention is a heating resistor film that generates thermal shock by continuous overcurrent application to an insulating substrate that is crushed by thermal shock. And a pair of electrodes are connected to the side edges of the heating resistance film and enclosed in an airtight container together with an arc extinguishing gas, and external terminals are connected to the electrodes, respectively. It is characterized by being derived outside.

[0008]

[Function] An insulating substrate that is crushed by thermal shock is coated with a heating resistance film that generates thermal shock when a continuous overcurrent is applied, and a pair of electrodes is connected to the side edges of the heating resistance film. Is enclosed with the arc extinguishing gas in an airtight container,
By connecting external terminals to the electrodes and leading them to the outside of the airtight container, first, when an overcurrent flows through the heating resistance film, the thermal shock causes the insulating substrate to shatter. When an excessive voltage is still applied between the cut heating resistance films, an arc discharge is about to be generated between the ends of the cut heating resistance films, but the arc-extinguishing gas is generated in the airtight container. Since it is enclosed, the overcurrent is cut off without generating an arc discharge. Further, since the arc extinguishing gas is difficult to conduct the heat generation of the heat generating resistance film generated by the overcurrent, the arc extinguishing gas does not change the current interruption characteristic.

[0009]

1 is an exploded perspective view of a fuse resistor showing a fuse resistor of the present invention. In the figure, 1 is a fuse resistor, which is made of a ceramic such as alumina, forsterite, steatite or the like, and has an insulating substrate 2 having a thickness of 0.1 to 1.0 mm. A heating resistance film 3 made of paste or the like having a resistance value of about 0.05 to 1.0 Ω is adhered, and a pair of extraction electrodes 4 made of an electrically good conductor such as Ag / Pd-based paste is attached to both ends of the heating resistance film 3. , 4 are adhered and formed, and the extraction electrodes 4, 4 are led out to both side edges of the insulating substrate 2 to form external terminal connection portions 4a, 4a. The external terminal connection portions 4a, 4a are provided with iron-nickel. The external terminals 5, 5 made of an alloy, 4-2-6 alloy, Dumet wire, etc. are fixed by soldering or the like. Then, the extraction electrodes 4 and 4 excluding the external terminal connection portions 4a and 4a, and the heating resistance film 3
Is covered with a protective film 6 made of lead-free glass such as borosilicate glass or bismuth glass to a thickness of 10 μm to 100 μm, thereby preventing the occurrence of creeping discharge that is likely to occur in the exposed energized portion.

The insulating substrate 2 to which the external terminals 5 and 5 are connected in this manner is vertically sandwiched between the enclosures 7 and 7 made of ceramic such as forsterite or glass or the like, and the external terminals 5 and 5 are enclosed. , 7 outside, the outer edges of the envelopes 7, 7 are sealed with frit glass or the like to form the airtight container 8. Although not particularly shown, arc-extinguishing gases such as sulfur hexafluoride (SF ₆ ) and nitrogen (N ₂ ) are previously enclosed in the airtight container 8.

The fuse resistor 1 of the present invention having the above structure
Built into the input stage of the power supply and signal in various equipment, when a continuous overcurrent flows from this equipment to the outside,
First, this continuous overcurrent flows through the heat generating resistance film 3 of the fuse resistor 1 to generate a thermal shock and crush the insulating substrate 2. As a result, the heat generating resistance film 3 is cut to block an overcurrent passing through the heat generating resistance film 3, and the arc extinguishing gas described above generates an arc discharge between the ends of the cut heat generating resistance film 3. To prevent overcurrent.

[0012]

As described in detail above, according to the fuse resistor of the present invention, a heat generating resistance film that generates a thermal shock due to continuous overcurrent application is attached to an insulating substrate that is crushed by a thermal shock. , A pair of electrodes were connected to the side edges of the heating resistance film, and this was enclosed in an airtight container together with an arc extinguishing gas, and external terminals were connected to the electrodes and led out to the outside of the airtight container. Therefore, first, when an overcurrent flows through the heating resistance film, the insulating substrate is crushed by the thermal shock, and if an excessive voltage is still applied between the cut heating resistance films, the cut heating resistance film An arc discharge tends to be generated between the ends, but since the arc extinguishing gas is enclosed in the airtight container, an arc discharge is not generated and the overcurrent is ensured without changing the desired breaking characteristics. To shut off.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a fuse resistor of the present invention.

[Explanation of Codes] 1 Fuse resistor 2 Insulating substrate 3 Heating resistance film 4 Extraction electrode 7 Envelope 8 Airtight container

Claims (1)

[Scope of utility model registration request] 1. An insulating substrate that is crushed by thermal shock is coated with a heating resistance film that generates thermal shock when a continuous overcurrent is applied, and a pair of electrodes is connected to a side edge of the heating resistance film. A fuse resistor characterized in that it is enclosed in an airtight container together with an arc extinguishing gas, and external terminals are connected to the electrodes and led out to the outside of the airtight container.