JPS5854452B2 - electric wire fuse - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire fuse with improved breaking performance and airtightness.

Conventional wire fuses come in two types: partially open types that release the cutoff gas pressure outside the fuse when cutoff occurs due to short circuits, and sealed types. They emit gas, which is not desirable in terms of environmental safety, and because they are partially open, there is a risk that the fuse element will become contaminated and deteriorate in the polluted atmosphere or in coastal areas due to salt damage.

In addition, the sealed type uses thick resin such as strong polycarbonate, has a double structure of fiber and polycarbonate, and fills the breaking part with arc extinguishing agent in order to contain the explosive power at the time of breaking. Methods such as these were used.

However, because it is completely sealed, large gas pressures are generated due to the metal gas in the element when shutting off and the combustion gas on the resin surface due to the high heat when shutting off, and it is difficult to create a structure that can withstand this. There were drawbacks such as a decrease in insulation resistance between both terminals of the fuse (more than 0.2 MΩ at 500 V) due to carbonization of the surface and adhesion of combustion gas to the resin.

Furthermore, due to the difference in thermal expansion between the sleeve and the resin on the airtight surface, it has been difficult to completely prevent moisture from being sucked in as air enters and exits through slits generated in the joint due to heat cycles.

The present invention greatly suppresses the cutoff gas pressure at the time of cutoff, facilitates complete sealing of the wire fuse, greatly suppresses the decrease in insulation resistance value after cutoff, and significantly improves airtightness. As shown in FIG. 1, one end 3 of the conductor wire 2 having partially narrow cutoff portions 5 on both sides of the low melting alloy 1 is heated to melt the low melting alloy 1. After the narrow breaker part 5 of the fuse element inserted and connected and the inner part of the conductor wire 2 are covered by passing through a small diameter heat-resistant ceramic tube 6, the conductor wire is inserted into a large diameter ceramic tube 7. The other end 8 of the wire 2 is inserted into the tube with the other end 8 protruding from the tube, and the metal cap 10 with which the wire connection sleeve 9 is integrated is capped and sealed with an inorganic heat insulating material 12 interposed therebetween. A fuse body a is formed by airtightly connecting the other end 8 of the conductor wire 2 and the wire connection sleeve 9 by compression, soldering, or both, and the wire connection portion of the wire connection sleeve 9 is made to protrude. It is inserted airtight into the resin case 11.

In addition, as shown in FIG. 2, the metal cap 10 is a bowl-shaped cap, and the resin case 11 is replaced by a resin mold 1.
It can also be set to 1.

In this case, the metal cap 10 may have the shape shown in FIG. 1, but by forming it into a bowl shape, it is possible to avoid increasing the thickness of the metal cap 10. This is effective in preventing severe deformation of the metal cap 10 due to the high pressure of the injected resin in the mold when injection molding is performed using a resin such as the above.

In addition, the large diameter ceramic tube 7 is a transparent glass tube, and the first
By making the cylindrical portion of the resin case 11 shown in the figure and at least the cylindrical portion of the resin mold 11 of FIG. There is.

With the above structure, the low melting metal 1 and the conductor wire 2 of the fuse element are first connected by heating one end 3 of the conductor wire 2 in the low melting alloy 1 to melt the low melting metal 1. Since the welding area is large because the welding area is large and one end 3 of the conductor wire 2 is inserted into the low melting alloy 1, the adhesion is perfect and unlike conventional methods. , the repeated instantaneous melting of the adhesive surface that occurs when a large current flows repeatedly for a short period of time, such as the starting current of an electric motor, which occurs in the case of surface bonding, which gradually causes the surface bonded part to shift, eventually leading to melting. This is completely eliminated, and it is possible to obtain a fuse that is stable over time and will not blow out at a predetermined current other than the large current at the time of an accident.

Further, in the electric wire fuse of the present invention, the narrow breaker part 5 of the fuse element and the inner part of the conductor wire 2 are heat-insulatingly coated with a heat-resistant ceramic tube 6 such as porcelain, and the outside is covered with an inorganic material such as porcelain or a transparent glass tube. Since it is covered by the metal cap 10 via the large diameter ceramic tube 7 and the inorganic heat insulating material 12, when the narrow breaker section 5 breaks off the arc, the heat-resistant ceramic tube 6 is able to handle the arc. It is shielded and arc heat is greatly reduced.

Since the remaining arc heat is shielded by the large diameter ceramic tube T and the metal cap 10 with inorganic heat insulating material 12 such as ceramic paper on both sides, there is no burning out of the resin case 11 or the resin mold 11 due to the interrupting arc. .

For this reason, the inner wall surface of the organic material container is directly exposed to arc heat, as in conventional electric wire fuses made of explosion-proof materials such as resin or fibers, and is instantaneously burnt out and gasified, creating a very large gas pressure, causing the fuse element itself to Explosive force at the time of shutoff, such as when the resin container is superimposed on the shutoff gas and bursts, or when the ridge part flies off, is greatly reduced, and the strength of the case is also reduced, and the ridge part is pinned to the case. It can be sealed without any need to do anything.

In addition, since the resin and the inner surface of the container are not carbonized, there is no drop in insulation resistance between both terminals on the shield side edge, and the most important problem in sealing electric wire fuses, which is a countermeasure against leakage, can be solved with a simple structure. It has excellent functions such as being completely explosion-proof and greatly reducing the strength of resin explosion-proof containers.

In addition, some conventional electric wire fuses have a double structure using glass tubes, but the ridges on both sides of the glass tube are made of resin, or the glass tube is thin, so the arc heat when it is cut off can damage the glass tube. In order to prevent the resin gas pressure generated at that time from being easily suppressed by instantaneous penetration and burning out the inner surface of the resin outer tube, a strong container that can withstand the gas pressure is required.
Although an arc extinguishing agent or the like was required in the breaker section, in the present invention, as described above, the narrow breaker section 5 and the conductor wire 2
The inner part of the tube is covered with a small-diameter heat-resistant ceramic tube 6, and the outside is further interposed with an inorganic ceramic tube such as a glass tube and an inorganic heat insulating material 12, and a metal cap 10 is used to shield arc heat, thereby preventing resin burnout. In order to reduce the explosive force caused by the gas pressure when the fuse is cut off, no arc extinguishing agent is required, and the fuse can be easily sealed in an explosion-proof manner.

Furthermore, in terms of airtightness, the large-diameter ceramic tube 7 such as a transparent glass tube and the metal cap 10 are sealed with an inorganic adhesive, and the connection between the other end 8 of the conductor wire 2 and the wire connection sleeve 9 is compressed. Since the seal is made by soldering, there is little difference in the thermal expansion coefficient between the members at the bonded part, so there is no risk of airtightness leaking from the bonded surface even during heat cycles, and a complete airtightness can be maintained.

Furthermore, the outside of the fuse body a is double airtight with a resin case 11 to ensure completeness, and also protects the large diameter ceramic tube 7 from mechanical shock and provides insulation protection for the metal cap 10. This is to ensure safety.

Furthermore, when the fuse body a in FIG. 2 is made of a resin mold 11, the large diameter ceramic tube 7 and the metal cap 10 as well as the wire connection sleeve 9 and the resin mold 11 are in complete contact with each other, and there is no air between them. Since there is no layer, there is no expansion or contraction of the air layer during heat cycles, so there is no air inflow or outflow, making it even more effective in terms of airtightness, and also making it easier to bond the cylindrical part and the cap like in the case of resin cases. It has many features such as saving time and being more economical to manufacture.

The electric wire fuse of the present invention has a feature that it can be applied to fuse elements of any structure.

[Brief explanation of the drawing]

1 and 2 are sectional views for explaining the electric wire fuse of the present invention. 1 is a low melting alloy, 2 is a conductor wire, 3 is one end of the conductor wire 2, 4 is a welded part, 5 is a narrow cutoff part, 6 is a heat-resistant ceramic tube, 7 is a large diameter ceramic tube, 8 is a conductor The other end of line 2,
9 is a wire connection sleeve, 9' is a wire connection portion of the wire connection sleeve, 10 is a metal cap, 11 is a resin case or resin mold, and 12 is an inorganic heat insulating material.

Claims (1)

[Scope of Claims] 1. Narrowing of a fuse element in which one end of a conductor wire having a narrow cut-off part on both sides of a low-melting alloy is heated and inserted while melting the low-melting alloy. After covering the breaker part and the inner part of the conductor wire with a small-diameter heat-resistant ceramic tube, the conductor wire is inserted into a large-diameter ceramic tube with the other end protruding outside the tube, and the wire connection sleeve is integrated. A fuse body is formed by sealing a metal cap with an inorganic heat insulating material interposed between the cap and the conductor wire inserted into the wire connection sleeve and the wire connection sleeve being hermetically connected by compression, soldering, or both. An electric wire fuse characterized in that the electric wire connection portion is made to protrude and is hermetically sealed in a resin case. 2 One end of a conductor wire that has a narrow cut-off part on both sides of the low-melt alloy is heated and inserted while melting the low-melt alloy to connect the narrow cut-off part of the fuse element and the conductor wire. After covering the inner part of the tube with a small-diameter heat-resistant ceramic tube, the conductor wire is inserted into the large-diameter ceramic tube with the other end protruding outside the tube, and a bowl-shaped metal cap with an integrated wire connection sleeve is attached with an inorganic The fuse body is formed by interposing a heat insulating material, sealing the cap, and airtightly connecting the conductor wire inserted into the wire connection sleeve and the wire connection sleeve by compression, soldering, or both, and the wire connection. An electric wire fuse characterized by having a protruding portion, resin molded, and hermetically sealed. 3 One end of a conductor wire that has a narrow cut-off part on both sides of the low-melt alloy is heated and inserted while melting the low-melt alloy, and connected to the narrow cut-off part of the fuse element and inside the pipe of the conductor wire. After covering the section with a small-diameter heat-resistant ceramic tube, the conductor wire is inserted into a large-diameter transparent glass tube with the other end protruding outside the tube, and a metal cap with an integrated wire connection sleeve is wrapped with an inorganic heat insulating material. The fuse body is formed by capping and sealing the conductor wire inserted into the wire connection sleeve and the wire connection sleeve by compressing or soldering, or both, and the wire connection portion is sealed. An electric wire fuse, characterized in that at least a cylindrical portion thereof is protruded and hermetically sealed as a transparent resin within a resin case or by a resin mold.