JPH0249629Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an isolation structure between a fuse operation display device and a fuse element.

FIG. 1 shows an example of the structure of a conventional fuse and its operation display device, in which a fuse element 3 whose both ends are connected to the terminal member 1 is arranged in an insulating tube 2 whose both ends are closed with the terminal member 1. The display fuse element 4 is arranged so as to be electrically parallel to the fuse element 3. The operation display device 5 is installed so as to protrude outward from one terminal member 1. The area around the display fuse element 4 and the fuse element 3 except for the inside of the operation display device 5 is filled with granular arc extinguishing agent 6.

One end of the display fuse element 4 passes through an insulating sleeve 7 to insulate from the terminal member 1, enters a display device chamber 5a that is installed to protrude outward from the terminal member 1, and connects to one end of the display rod 5c. The end of the display rod 5c is fixed to the terminal member 1 in a state where the display rod 5c, which is always biased by the compression spring 5b in the direction of protruding from the display device chamber 5a, is held back through the transverse hole 5d provided in the display device chamber 5a. . The crimp sleeve 8 is crimped and fixed to the display fuse element 4 where the display fuse element 4 enters the insulating tube 2 from the insulating sleeve 7 in order to hold the display rod 5c in a restrained state against the compression spring 5b. be done.

The length of fuse element 3 and display fuse element 4 increases depending on the rated voltage of the fuse, and for high voltage fuses they are bent into a spiral or wave shape (not shown) to shorten the overall length of the fuse. This is taken into consideration.

Here, the terminal member 1 is made of copper,
The insulating tube 2 is made of porcelain, the fuse element 3 is made of silver, the display fuse element 4 is made of nichrome wire, the display device 5a is made of copper, the compression spring 5b is made of spring steel, the display rod 5c is made of brass, the arc extinguisher 6 is made of silica sand, and the insulating sleeve 7 is made of porcelain,
The crimp sleeve 8 is made of copper.

When an overcurrent flows through the fuse configured as described above, the fuse element 3 and the display fuse element 4 melt and arc, and the vaporized fuse element material diffuses between the particles of the arc extinguisher 6 and is cooled. to cut off the overcurrent. and display fuse element 4 in display device chamber 5a.
Even if it melts, it turns into steam and is blown away because it is in the air, and the display rod 5c is released from its hold and is pushed out from the display device chamber 5a by the force of the push spring 5b, as shown in FIG. 1B. Operates to indicate that the fuse has operated.

In the figure, dotted lines 3a and 4a indicate products formed between the fuse element 3 and the display fuse element 4 after the fuse element 3 and the display fuse element 4 are fused and the arc extinguisher 6 is present after the current is cut off.

The above-described fuse has the disadvantage that the operation display device 5 protrudes beyond the terminal member 1, resulting in a large external dimension. Therefore, the second
As shown in the figure, an operation display device 5 is often attached to the inner surface of one terminal member 1 and housed inside the fuse.

However, in this case, the fuse element 3 has no special support and maintains its position only by its own elasticity by bending it into a spiral or wave shape, so its position is unstable. If a sufficient distance is not maintained between the operation display device 5 and the fuse element 3, the fuse element 3 is likely to approach or come into contact with the operation display device 5.
When the fuse element melts, the operation display device 5 may be damaged by the heat, or a flash may occur between the tip X point of the operation display device 5 and the close Y point of the fuse element 3, causing the arc generated in the fuse element portion to The outer diameter of the insulating tube 2 of the fuse is made thicker than necessary because the length between the Y point and the end Z point is shortened, and a sufficient length cannot be obtained, resulting in a decrease in the cutting performance. The drawback is that you have to do it.

This invention attempts to eliminate the above-mentioned drawbacks of the conventional device by providing an isolation insulator on the outside and tip of the operation display device.

Hereinafter, a fuse in an embodiment of this invention will be explained based on FIG. In the figure, 1 to 8
Since it is similar to the conventional one shown in FIG. 2, the explanation will be omitted. Reference numeral 9 denotes an insulator attached to the outer tip of the operation display device 5. This insulator 9 has an outer diameter A that is at least twice as thick as the interval B required between the fuse element 3 and the operation display device 5, and a length C that is set so that the fuse element 3 is spirally wound. If it is bent into a wave shape, it is made longer than the winding pitch D, and if it is bent into a wave shape, it is made longer than the bending pitch (not shown).

Here, it is important that the length C of the insulator 9 is longer than the winding pitch D or bending pitch of the fuse element 3. If it is shorter than this, it will be one turn if it is wound in a spiral shape, or one turn if it is bent in a wave shape. In this case, the insulator 9 will enter into one wave and the isolation effect will be lost, so care must be taken. As for the material, porcelain is suitable in terms of heat resistance, but glass, resin, etc. are also effective.

Since the insulator 9 is configured as described above, even if the position of the fuse element 3 is unstable, it can be reliably isolated from the operation display device 5, and when the fuse element 3 is blown, the heat can be used to prevent the fuse element 3 from melting. It functions to prevent the operation display device 5 from being damaged and from causing a flashover between the fuse element 3 and the operation display device 5.

As described above, according to this invention, there is an insulating material at the end of the side through which the display fuse element of the operation display device passes through, which is thicker than the outer diameter of the operation display device and longer than the helical winding pitch or wave-shaped bending pitch of the fuse element. This has the effect of providing a fuse with excellent performance and small external dimensions.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing the configuration of a conventional fuse, respectively, where A is a cross-sectional view showing the state before operation, B is a cross-sectional view showing the state after operation, and FIG. 3 is a fuse in an embodiment of this invention. FIG. In the figure, 1 is a terminal member, 2 is an insulating cylinder, 3 is a fuse element, 4 is a display fuse element, 5
1 indicates an operation display device, 6 indicates an arc extinguisher, and 9 indicates an insulator. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] An insulating tube whose both ends are sealed with a terminal member and filled with arc extinguishing agent, and either a spiral or wavy shape whose both ends are connected to the terminal member and housed in the insulating tube. a fuse element, an operation display device having an indicator rod housed in a display device chamber disposed at one end of the insulating cylinder and urged outwardly by a compression spring; and a display fuse element that holds the display rod in the display chamber against the compression spring, the fuse being disposed at an outer end of the display chamber on the side through which the display fuse element penetrates. an outer diameter larger than an outer diameter of the display device chamber by at least a distance that can withstand a recovery voltage generated between the display device chamber and the fuse element when the fuse element is blown, and a helical winding of the fuse element. A fuse comprising an insulator having a length greater than either the pitch or the corrugated bent pitch.