JPH0347244Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is an electric circuit mainly using semiconductor elements, which has a relatively small capacity (for example, a rated current value of 1 ampere to 15 amperes) that protects the element from overcurrent. This invention relates to the structure of a so-called quick-acting current-limiting fuse that is agile in operation.

The structure of a conventional fast-acting current-limiting fuse is, as shown in FIG. A thin copper wire lead wire 7 is wound and fixed around both ends of a supporting rod 6 made of an insulating material, as shown in FIG. It is well known that a fusible body with support rods, in which a fusible body 3 is stretched and fixed by solder 20, is disposed in an insulating cylinder 2 together with an arc extinguishing agent 5.

However, the above method had the following drawbacks.

(1) The item A in Figure 1 uses a fusible wire material with an ultra-fine wire diameter, so there are many wire breakages during assembly, and the soldering process requires skill, and the finished product is susceptible to vibrations and
It is also vulnerable to mechanical stress such as impact.

(2) The one shown in Figure 1 (b) is mass-produced because the process of winding and fixing thin copper wire lead wires around both ends of the support rod and the process of stretching a fusible wire rod in this gap and fixing it by soldering are time-consuming. I can't.

Furthermore, depending on the rated current value, some properties cannot be obtained unless the wire soluble material is wound around the support rod, and it is difficult to control the number of times of winding, resulting in a lot of loss in production.

(3) What is common to both A and B in Figure 1 is that there is a JISC6575 standard for fast-acting fuses, and this standard specifies the characteristic symbol SH or SL (the former is for overcurrent of 200% of the rated current). Within 0.5 seconds, the latter is 1 at an overcurrent of 250% of the rated current.
In order to satisfy this requirement, the fuselable material must be extremely thin and have a relatively long effective length. The electrical resistance increases, and when the rated current is applied, the temperature of the fuse body due to the heat generated by the fusible material rises extremely high, and even a fuse with a small rated capacity reaches a high temperature.

(4) It has been proven that, theoretically, the shorter the length of the fusible body, the more rapid cutting performance can be achieved, but conventional products, on the other hand, have a long effective length of the fusible body. Therefore, there is almost no margin for obtaining a fusing time that satisfies the specifications for the characteristic symbols SH and SL, and there is also a concern that the stipulated time may be exceeded due to variations in the wire fusible material, wire diameter, wire length, etc.

In addition, in terms of cutting performance, if the effective length of the wire fusible material is long, even if a thin wire with a cross-sectional area smaller than 0.25 mm in diameter is used, the total length of the stretched fusible material will be As the melting occurs all at once, the arc beam generated by the increase in the arc voltage within the cylinder continues in the straight direction of the fusible material and reaches the cup-shaped caps at both ends, causing holes in the caps and making them unbreakable. Easy to do.

The present invention was developed in view of the above-mentioned drawbacks, and uses a fusible material with an effective length of 2.5 mm to provide reliable rapid cutting performance, extremely low electrical resistance and temperature rise, and has excellent cutting performance. The object of the present invention is to provide a fast-acting current-limiting fuse that is resistant to mechanical stress and is easy to manufacture.

The details of the present invention will be explained below based on one embodiment. Note that common parts in the figures have the same part numbers.

FIG. 2A shows a heat-resistant insulating sheet 11 made of, for example, a silicone resin laminate and having a length L. Copper foil tape 12 with adhesive is attached to both ends of the heat-resistant insulating sheet 11 with an extra length 12a,
12b and the blank part 1 of the insulating sheet 11
1a and 11b, and a small hole 1 with a diameter of 2 mm is formed in the center (1/2L) of the front and back surfaces of the copper foil tape 12.
1c at equal intervals, and then cut them at points P ₁ to Pn to have a predetermined width W to form the strips shown in Figure B,
Small hole 1 in the center of this strip (1/2L of total length L)
The wire fusible body 3 is inserted through 1c, and the copper foil tape 12 is inserted.
A fusible material holding substrate A as shown in FIG. 3A is formed on one end of the front and back surfaces of the substrate with solder 20, respectively.
FIG.
c and are fixed in an S-shape at intervals of approximately 2.5 mm.

FIG. 4 is a perspective view showing the assembly process of the quick-acting current-limiting fuse according to the present invention. In FIG. One end 12a of the foil tape 12 is inserted into the rectangular hole 4a of the washer 4, bent and closed.
As shown in FIG.
The other end 12b is inserted into the rectangular hole 4'a of the washer 4' and closed by bending. Next, as shown in FIG. Base 1,
By heating the bottom surfaces 1a and 1'a of 1' and fitting them together, a quick-acting current-limiting fuse having a structure for obtaining an electrical connection as shown in FIG. 2 is completed. FIG. 5 shows a vertical cross-sectional view of the inside.

As described above, the quick-acting current-limiting fuse of the present invention is
Since the wire fusible material 3 used electrically is stretched at extremely short intervals of approximately 2.5 mm, the electrical resistance value is small, and the temperature rise during energization is also low, making it easy to handle in low overload and disconnection areas. Fast cutting performance is obtained, and in the short-circuited area where a large current passes and the wire fusible material 3 inserted through the hole 11c in the center of the fusible material holding substrate A melts instantly, the arc generated at that time is not filled. It is suppressed by the arc extinguishing agent 5 and disappears only in the circumferential region of the hole 11c in the center of the substrate A, and does not persist to the cup-shaped caps at both ends, resulting in a good current limiting effect.

The results of the shear test show that the surface of the copper foil tape 12 in the circumferential area of the hole 11c in the center of the substrate A is insulated because the periphery of the hole 11c is melted concentrically by the melting arc of the fusible body 3. The sheet 11 is not carbonized by heat at all, has good insulation resistance after being cut, and is safe. Furthermore, mechanically and structurally, the wire fusible body 3 is supported and fixed on the fusible body holding substrate A, so it is strong and has a long life in terms of vibration resistance and impact resistance.
A highly reliable product can be obtained.

Further, both ends 12a and 12b of the substrate A placed in the insulating cylinder 2 together with the arc extinguishing agent 5 are cup-shaped caps to which solder 20 is welded in advance via washers 4 and 4' because the solder has extremely good wettability. 1 and 1' are securely soldered and connected from the inside, making the fast-cutting shape electrically stable and aesthetically pleasing as the solder 20 is not exposed on the end surfaces of the cup-shaped caps 1 and 1'. It has advantages such as being able to provide a flowing fuse.

[Brief explanation of drawings]

Figures 1A and 1B are longitudinal cross-sectional views of a conventional quick-acting current-limiting fuse, Figure 2A is a perspective view of an insulating sheet with adhesive-coated copper foil pasted, and Figure 2B is a cut-out view of the insulating sheet. FIG. 3A is a perspective view of a fusible material holding substrate used in the quick-acting type current limiting fuse of the present invention, FIG. 3B is a cross-sectional view of A, and FIG. A perspective view showing the assembly process of the current limiting fuse.
FIG. 5 shows a longitudinal cross-sectional view of a completed quick-acting current-limiting fuse of the present invention. Part number 1 is a cup-shaped cap, 2 is an insulating cylinder, 3 is a wire soluble material, 4 is a washer, 5 is an arc extinguisher, 6 is a support rod, 7
11 is a lead wire, 11 is an insulating sheet, 12 is a copper foil with adhesive, 20 is solder, and 21 is an adhesive.

Claims (1)

[Scope of utility model registration request] A strip of adhesive-coated copper foil tape 12 is pasted on both sides of a heat-resistant insulating sheet 11 in a predetermined pattern with blank areas 11a and 11b, and has a total length L and a width W, and a strip that is 1/1/2 of the total length of this strip. A small hole 11c with a diameter of 2 mm is drilled at the position 2L, and the wire fusible body 3 is inserted through this small hole 11c, and the effective length is approximately
A fusible material holding substrate A is fixed to one end of the front and back surfaces of the copper foil tape 12 with a solder 20 while maintaining an interval of 2.5 mm, and this substrate A.
The insulating tube 2 is filled with an arc extinguishing agent 5 filled inside the insulating tube 2, both ends of the insulating tube 2 are closed with washers 4, 4', and the cup-shaped caps 1, 1' are filled. A quick-acting current-limiting fuse that features a structure that allows electrical connection by fitting the fuse.