JPS5937538B2 - Fuse - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the holding structure of fuses, particularly of fuse elements.

Figure 1 shows the typical structure of a conventional fuse.
A fuse element 3 whose both ends are connected to the terminal metals 1, 1 is disposed in a fuse cylinder 2 whose both ends are sealed with terminal metals 1, 1, and the fuse element 3 is embedded in an arc extinguisher 4. be done.

The length of the fuse element 3 is 2 of the length of the fuse tube 2.
It is normal for the fuse element 3 to be wound up to 3 times as much, so the fuse element 3 is wound into a spiral as shown in FIG.

As for the constituent materials, porcelain or resin tube is generally used for the fuse tube 2, copper for the terminal metal 1, silver for the fuse element 3, and granular silica sand of about 10 to 200 meshes for the arc extinguisher 4. ing.

In a fuse with such a structure, when an overcurrent flows, the fuse element 3 melts and generates an arc, and the vaporized fuse element material diffuses into the gap between the arc extinguishing agent 40 particles as shown by the arrow in Figure 2. At the same time, the arc extinguishing agent 4 is melted and cooled by its latent heat of melting to instantly become an insulator, thereby interrupting overcurrent.

After operation, a glassy molten product 34 with diffused fuse element material is formed as shown in FIG.

The size of this molten product varies depending on the design of the fuse element and arc quenching agent, but in a typical fuse, the diameter is large, ranging from 2 to 101 nm.

The temperature of the molten product when the fuse is operating is several thousand degrees Celsius, but because the heat conduction of the surrounding granular arc-extinguishing agent is low, the temperature of the fuse cylinder does not rise to that level and it is protected from destruction. .

However, if the fuse element is in contact with or close to the fuse tube and the molten product comes into contact with it, the fuse tube will crack due to heat shock in the case of porcelain, or it will catch fire and burst if it is a resin tube.

Now, considering the case where the fuse element is wound into a spiral shape as shown in FIG. 1 and disposed within the fuse cylinder, the position of the fuse element 3 is maintained by its own springiness.

Considering the force balance at the center point A of the fuse element in this case, as shown in Figure 4, there is a constant tension F due to the fuse element's own springiness in the length direction of the fuse element.
1 is acting, but if even a small external force F2 is applied in the radial direction due to vibration, impact, etc., a large displacement occurs to balance this.

It is easy to think that the arc extinguisher protects this displacement of the fuse element, but in reality, the arc extinguisher itself moves and circulates within the fuse cylinder due to vibrations, shocks, etc., and the fuse element easily moves through the arc extinguisher. It is something.

For this reason, it becomes unstable to maintain the radial position of the fuse element, so a considerable distance is required between the fuse element and the fuse tube, and the fuse tube needs to be thick. Fuse element storage efficiency deteriorates.

This invention was made by focusing on the above-mentioned drawbacks of the conventional technology, and the fuse is placed in a polygonal heat-resistant insulating tube (hereinafter referred to as an insulating tube). By storing the fuse element, a gap is created between the fuse element and the fuse tube so that the fuse element does not come into contact with the fuse tube, thereby providing a fuse that does not have the drawbacks of the conventional ones. be.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

5 and 6 show →1 of the present invention, FIG. 5 is a longitudinal cross-sectional view, and FIG. 6 is a machine cross-sectional view along the line Vl-■ in FIG. 5.

As shown in the figure, the structure is the same as the conventional one shown in FIG. 1, except that the fuse element 3 is placed in an insulating tube 5 having a triangular cross section and housed in the fuse tube 2.

The fuse element 3 is spirally wound, and the arc extinguisher 4 is filled inside and outside the insulating cylinder 5.

Next, the operation of this invention will be explained.

As explained in FIG. 4 above, a fuse whose fuse element is spirally wound and stretched by its own springiness becomes unstable in maintaining the position of the fuse element in the radial direction. As shown in FIG. 6, the two sides of the insulating cylinder 5, which has a triangular cross section, prevent the fuse element 30 from moving in the radial force direction, thereby preventing it from coming into contact with or approaching the fuse cylinder 2.

As a result, the molten product of the fuse element does not come into contact with the fuse cylinder 2 and damage it, unlike in the conventional case.

In this case, as shown in FIG.
Fuse element 3 with a winding diameter such that it is inscribed in the inner wall of
, the fuse element 3 becomes a triangular round cylinder 5.
It is held at the three sides of the fuse tube 2, does not move at all in the radial direction, and is always held at the center of the fuse tube 2, providing extremely stable performance.

The conditions for this are as follows, assuming that the inner diameter of the fuse tube 2 is D and the thickness of the insulating tube 5 is ignored.

Length of side of insulating tube 501 - Winding diameter of fuse element 30 - - The material of insulating tube 5 is such that the fuse element material vaporized by melting and arcing of fuse element 3 easily permeates the wall of insulating tube 5. As long as the arc extinguishing agent 4 has air permeability such that it can diffuse into the arc extinguishing agent 4 outside the insulating tube 5, the presence of the insulating tube 5 will have little effect on the breaking performance.

Therefore, it is better to have a thinner thickness as long as it has sufficient strength to prevent displacement of the fuse element.

Furthermore, it is more effective if the insulating tube 5 itself is made of a material that cools the arc by its latent heat of fusion and aids in the arc extinguishing action, similarly to the arc extinguishing agent 4.

There are tubes made of fibrous heat-resistant insulators that satisfy the above conditions, and it has been confirmed that good results can be obtained by using glass cross tubes as a typical example. There is.

In a fuse with such a configuration, overcurrent flows,
When the fuse element melts and generates an arc, the fuse element material evaporates and some of it is diffused into the gaps between the arc-extinguishing agent particles in the insulation cylinder, and also into the insulation cylinder. The remainder passes through the wall of the insulating tube and diffuses into the arc extinguishing agent outside the insulating tube, cools down, and instantly becomes an insulator to cut off the overcurrent.

After the operation, a molten product 4 is formed in which the arc extinguishing agent inside and outside the insulating cylinder and the components of the insulating cylinder are integrated, as shown in Fig. 8.
I can do 5.

In the above description, the insulating cylinder is explained using an example of a triangular cross section, but the invention is not limited to this. For example, an insulating cylinder having a rectangular shape as shown in FIG. You can also get the same effect.

However, if the number of angles increases too much, the shape gradually approaches a circle, and the effect of isolating the fuse element and the fuse tube becomes weaker, and in practical terms, a square shape is effective.

It is also possible to make a modification in which each side of the polygon is slightly curved inward, as shown in Figure 10, but in this case,
Although the effect of isolating the fuse element and the fuse tube is further achieved, there is a drawback that it is difficult to manufacture an insulating tube.

As described above, according to the present invention, since the fuse element does not come into contact with or approach the fuse tube and damage the fuse tube, the fuse tube can be made smaller and the storage efficiency of the fuse element can be improved. It is possible to obtain excellent practical effects.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the structure of a conventional fuse, Fig. 2 is a transverse sectional view explaining the operating process of the fuse, Fig. 3 is a transverse sectional view showing the state of the fuse after operation, and Fig. 4 is A vector diagram illustrating the force relationship for maintaining the position of the fuse element, FIG. 5 is a vertical sectional view showing the structure of the fuse of the present invention, and FIG. 6 is a sectional view 1 taken along the line VI-Vll of FIG.
The figure is a diagram explaining the ideal dimensional relationship of the structure of this invention,
FIG. 8 is a cross-sectional view showing the state of the fuse of the present invention after operation, and FIGS. 9 and 10 are cross-sectional views showing other different examples of the present invention. In the figure, 1 is a terminal metal, 2 is a fuse tube, 3 is a fuse element, 4 is an arc extinguisher, 5 is an insulating tube, and 34 and 45 are molten products. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A fuse tube whose both ends are closed by a pair of terminal metals and whose inner surface is approximately circular; a granular arc-extinguishing agent filled in the fuse tube; A helical fuse element is housed in the agent and has both ends electrically connected to the terminal metal, and a heat-resistant polygonal shape is provided between the fuse tube and the fuse element to prevent contact between the fuse tube and the fuse element. A fuse with an insulating tube. 2. The fuse according to claim 1, wherein the heat-resistant insulating tube has air permeability. 3. The fuse according to claim 1 or 2, wherein the heat-resistant insulating cylinder is made of a fibrous material. 4 Claim 3, characterized in that the heat-resistant insulating cylinder made of a fibrous material is a glass cloth tube.
Fuses listed in section.