JPH0116279Y2 - - Google Patents

Description

[Detailed description of the invention] Technical field This invention arranges an upper electrode and a relay electrode at both the upper and lower ends of an insulating outer cylinder, connects both electrodes with a fuse element wound around an insulating core, and The present invention relates to a current limiting fuse provided with a lower electrode connected to the relay electrode via a conductive plate, and a protective cover that covers the lower end of the insulating outer cylinder so as to cover the relay electrode.

Purpose The purpose of this invention is to provide a protective cover that prevents a fuse element wound around an insulating core from loosening in the counter-winding direction and from unnecessarily winding in the winding direction when assembling a current limiting fuse.

Embodiment Hereinafter, an embodiment embodying this invention will be described with reference to FIGS. 1 to 5.

An upper electrode fitting 3 having an upper contact blade 2 projecting thereon is fitted and fixed to the upper end (right end in FIG. 1) of the insulating outer cylinder 1 of the current limiting fuse F. A lower electrode fitting 4 is fixed to the center of the insulating outer cylinder 1, and a lower contact blade 5 is formed from the lower electrode fitting 4 and projects in the same direction as the upper contact blade 2.

The lower electrode fitting 4 is provided with a connecting portion 6 that protrudes toward the lower end of the insulating outer cylinder 1, and one end of a conductive plate 7 bent in a stepped manner is connected to the connecting portion 6 with a screw 8. The other end of the conductive plate 7 extends along the outer periphery of the insulating outer cylinder 1 toward its lower end, and is integrally formed with a ring-shaped relay electrode 9 that abuts against the lower end surface of the insulating outer cylinder 1. .

Further, an engaging piece 10 extending along the outer periphery of the insulating outer cylinder 1 is provided protrudingly provided on the side of the relay electrode 9 180 degrees opposite to the conductive plate 7 . That is, by arranging the conductive plate 7 and the engaging piece 10 in a clamping manner to the lower end of the insulating outer cylinder 1, the center of the circular insertion hole 16 formed at the center of the relay electrode 9 is insulated. Outer cylinder 1
The center of the axis is aligned with the center of the axis.

An insulating core 11 is housed in the axial direction of the insulating outer cylinder 1, and a fuse element 12 whose upper end is connected to the upper electrode fitting 3 is wound around the outer periphery of the insulating core 11. The fuse element 12 has a small current shield section 14 provided in the center and covered with an arc-extinguishing tube 13 made of fluororesin, etc., and a large current consisting of silver elements connected to both ends of the small current shield section 14. It is composed of a bow section 15.

The lower end of the fuse element 12 is located at the fifth
As shown in the figure, it is welded to the outer surface of the relay electrode 9 through a notch 17 formed in the insertion hole 16 of the relay electrode 9 at a position close to the conductive plate 7. Arc-extinguishing sand 19 is filled between the insulating outer cylinder 1 and the insulating core 11 and in the through hole 18 of the insulating core 11.

A display tube 20 whose inner end is fixed to the end of the insulating core 11 is inserted into the insertion hole 16 of the relay electrode 9,
It is fixed to the outer surface of the relay electrode 9 by a flange 21 at the outer end. The flange 21 has a locking part 22 formed by a cut and a recess 23, and the connecting part 12a of the lower end of the fuse element 12 in the relay electrode 9 corresponds to the recess 3. ing.

The lower end of the insulating outer cylinder 1 is covered with a cap-shaped protective cover 24 made of an insulating material. The inner bottom surface of the protective cover 24 is adhesively fixed to the flange 21 of the display tube 20 in a watertight manner via a water-resistant seal 25 such as a double-sided adhesive tape, and a tapered guide surface 26a is provided at the inner peripheral edge of the protective cover 24 at its center. A protrusion hole 26 is provided therethrough.

Further, the conductive plate 7 is provided on the inner peripheral surface of the protective cover 24.
and the longitudinal direction (vertical direction) corresponding to the engaging piece 10
A pair of engagement grooves 27 are recessed in such a way that both 7 and 10 can be engaged therein and have the same length in the longitudinal direction, thereby preventing the protective cover 24 from rotating in the circumferential direction. An epoxy resin adhesive 28 is filled between the protective cover 24 and the lower end of the insulating outer cylinder 1 in a watertight manner.

A display rod 29 whose outer end can protrude from the protrusion hole 26 of the protective cover 24 is housed in the display tube 20, and a flange 30 of the display rod 29 which can be locked on the inner surface of the peripheral edge of the protrusion hole 26 and a display. A spring 32 is interposed between protrusions 31 on the inner periphery of the inner end of the cylinder 20 to urge the display rod 29.

As shown in FIG. 3, the high resistance wire 33 is connected to the intermediate electrode 9 by having one end wound and hooked to the locking portion 22 of the flange 21 of the display tube 20. The same high resistance wire 33 is connected to the display tube 2 from the connection part.
It passes through the outside of the display tube 20 and is first wound and hooked a suitable number of times to one of a pair of hooks 34 and 35 formed at the inner end of the display tube 20. From there, it passes through the stop hole 36 formed at the center of the protrusion 31 at the inner end of the display tube 20, inserts the inner end of the display rod 29 in the completely retracted state, and from there passes through the stop hole 36 again to insert the other end. It is wound and fixed around the hook part 35 and is crimped and connected 38 within the base end of the insulating core 11 to the spiral part 37 connected to the upper electrode fitting 3 . The portion of the high-resistance wire 33 housed in the display tube 20 is tensioned by the repulsive force of the spring 32, and the two tensioned portions are connected to conical stop plugs 39 that are fitted into the stop holes 36. It is held between the protrusion 31. A recess 40 at the inner end of the display cylinder 20 formed by the protrusion 31 and stopper 39 is filled with an epoxy resin adhesive 41 in a watertight manner.

To explain the assembly of this current-limiting fuse F, the upper electrode fitting 3 and the lower electrode fitting 4 are fixed to the upper end and center part of the insulating outer cylinder 1, and the relay electrode 9 is attached to the insulating outer cylinder 1.
The conductive plate 7 and the engaging piece 1 are placed in contact with the lower end surface of the
0 is arranged in a clamping manner on the outer periphery of the insulating outer cylinder 1, and the upper end of the conductive plate 7 is connected to the connecting portion 6 of the lower electrode fitting 4 with 8 screws (see FIG. 4).

A high resistance wire 33 is wired in advance to the insulating core 11 and the display tube 20 as shown in FIGS. 2 and 3, and the fuse element 12 is wound around the outer periphery of the insulating core 11 and the display tube 20, which are assembled and fixed together. The fuse element 12 wound as described above is inserted into the insulating outer cylinder 1 through the insertion hole 16 of the intermediate electrode 9, with the insulating core 11 facing first.

Then, the upper end of the fuse element 12 is connected to the upper electrode fitting 3, and the lower end thereof is connected to the outer surface of the relay electrode 9 via the recess 17. Thereafter, a waterproof seal 25 such as double-sided adhesive tape is attached to the outer surface of the flange 21 of the display tube 20. Then, the protective cover 24 is inserted into the engaging groove 27 of the conductive plate 7.
The lower end portion of the insulating outer cylinder 1 is covered with the engaging piece 10. Therefore, the relay electrode 9 is brought into contact with the lower end surface of the insulating outer cylinder 1 via the protective cover 24, the water-resistant seal 25, and the flange 21 of the display cylinder 20. When the protective cover 24 is mounted on the insulating outer cylinder 1, the inner bottom surface of the protective cover 24 is fitted so that the recess 23 in the flange 21 of the display cylinder 20 corresponds to the connection part 12a of the fuse element 12 of the relay electrode 9. On the other hand, the flange 21 of the display tube 20
shall be adhered and fixed with the water-resistant seal 25.

Therefore, the protective cover 24 and the display tube 20 are fixed to each other as described above, and the conductive plate 7 and the engagement piece 10 are engaged in the engagement groove 27 of the protective cover 24, so that the protective cover 24 is attached to the insulating outer tube 1. The display tube 2 is fixed to the protective cover so that it cannot rotate in the circumferential direction.
0 and the insulating core 11 fixed to the display tube 20 are also accommodated in the insulating outer tube 1 without being rotated in the circumferential direction of the insulating outer tube 1.

Further, since both ends of the fuse element 12 are connected to the upper electrode fitting 3 and the relay electrode 9, respectively, the fuse element 12 does not move in the winding direction or in the counter-winding direction with respect to the insulating core 11 during assembly.

After the protective cover 24 is attached to the lower end of the insulating outer cylinder 1 in this manner, an epoxy resin adhesive 28 is filled between the protective cover 24 and the insulating outer cylinder 1 in a watertight manner. Thereafter, arc-extinguishing sand 19 is filled into the insulating core 11 and the insulating outer cylinder 1 through the opening (not shown) of the upper electrode fitting 3, and the opening (not shown)
Seal the container tightly (not shown).

As described above, since the protective cover 24 is provided with the engagement groove 27 for engaging the conductive plate 7 attached to the insulating outer cylinder 1, it can be attached to the insulating outer cylinder 1 without being able to rotate relative to it. Therefore, the display tube 20 fixed to the protective cover 24 during assembly and the insulating core 11 fixed to the display tube 20 are also rendered immovable relative to the insulating outer tube 1.

Therefore, the fuse element 12 whose lower end is connected to the relay electrode 9 provided integrally with the conductive plate 1 attached to the insulating outer cylinder 1 is connected to the insulating core 11.
Since the fuse element 12 does not rotate relative to the other end, a predetermined winding state of the fuse element 12 can be obtained.

In addition, in the case where the engagement groove 27 is omitted in the protective cover 24, the protective cover 24 can be removed during assembly.
There is a risk that the display tube 20 and the insulating core 11 fixed to the insulating outer tube 1 may rotate relative to the insulating outer tube 1, which may cause the insulating core 11 of the fuse element 12 to
This may cause problems such as the winding becoming loose or winding more than necessary. However, with this invention, those concerns are eliminated.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view showing the whole of an embodiment of this invention, Fig. 2 is a sectional view of the main parts, Fig. 3 is a perspective view of the display tube, and Fig. 4 is an exploded perspective view of the main parts. , FIG. 5 is a perspective view of the relay electrode. Insulating outer tube 1, upper electrode fitting 3, lower electrode fitting 4, conductive plate 7, relay electrode 9, engagement piece 10, insulating core 11, fuse element 12, display tube 20,
Protective cover 24, engagement groove 27, current limiting fuse F.

Claims (1)

[Claims for Utility Model Registration] 1. An upper electrode and a relay electrode are provided at both the upper and lower ends of an insulating outer cylinder, and the two electrodes are connected to each other by a fuse element wound around an insulating core, so that almost all of the insulating outer cylinder A lower electrode connected to the relay electrode via a conductive plate is provided on the outer periphery of the central part, and an indicator tube connected to the insulating core is installed at the lower end of the insulating outer tube and performs an indicating operation when the fuse element is blown. In the current limiting fuse, a pair of engagement grooves located 180 degrees opposite each other are formed on the inner circumferential surface of the bottomed cylindrical protective cover that covers the lower end of the insulating outer cylinder so as to cover the relay electrode. 1. A protective cover for a current-limiting fuse, characterized in that a conductive plate is provided in each case so as to be inserted therein, and a protrusion hole for protruding an indicator rod for performing an indicating operation of the indicator cylinder is provided in the bottom wall. 2. The conductive plate is formed integrally with the relay electrode, and an engaging portion is provided on the side of the relay electrode 180 degrees opposite to the conductive plate along the outer periphery of the insulating outer cylinder and capable of engaging in the engaging groove. A protective cover for a current-limiting fuse as set forth in claim 1 of the utility model registration claim, characterized in that: