JPS626643Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an electronic component that is directly connected between power lines, and when the electronic component is overrated and an excessive current flows into the component, the electronic component is electrically disconnected from the power line. The purpose of the present invention is to provide a device equipped with a mechanism that prevents burnout, etc.

A ceramic varistor will be explained as an example of an electronic component. Ceramic varistors, which are mainly made of zinc oxide, have been widely used in recent years to protect electronic devices from surge voltages caused by lightning, mainly by connecting them between power lines, and their protective effects are recognized as extremely excellent. It's coming.

However, when these varistors are subjected to stress that significantly exceeds their maximum ratings (eg, circuit voltage, energy withstand capacity, surge withstand capacity, power), there is a risk that short-circuit damage may occur. If an appropriate overcurrent breaker, such as a fuse, is not installed on the power supply side of the power line, the varistor may burn out and have a large negative impact on the surrounding area.

Conventionally, it has been recommended to attach a fuse to the external circuit as a countermeasure against burnout, but due to the problem of installation space for the fuse and the problem of increasing the cost of electrical equipment, there are many cases in which the equipment is used without such a fuse.

FIG. 1 shows the general structure of the varistor. 1 is a varistor body, 2 and 2' are lead wires taken out from the front and back sides of the varistor body 1, and 3 is an exterior coated with epoxy resin.
It covers part of 2'. This configuration requires the incorporation of a fuse into the external circuit.

The present invention is an electronic device that has a mechanism that blocks excessive short-circuit current to the varistor and prevents burnout when a short circuit occurs due to overload, etc., without requiring extra space and minimizing cost increase. It provides parts.

FIG. 2 shows the configuration using a varistor as an example. 4 is a varistor body, 5 and 5' are lead wires taken out from the front and back of the varistor body 4, 6 is an insulating exterior formed by coating with epoxy resin, etc., 7
is a coated part of the insulating sheath 6 to the lead-out part of the lead wires 5, 5', and is usually called a foot hanging part of the coating. Reference numeral 8 denotes a portion provided inside the coating foot sagging portion 7 and having an overcurrent interrupting function. If a short circuit occurs in the varistor body 4 for some reason, the overcurrent cutoff function section 8 will operate due to the current that flows in at that time, and the varistor body 4 will be virtually disconnected from the power line, resulting in burnout, etc. This will not lead to the spread of accidents. The overcurrent cutoff function section 8 is insulated by the insulating exterior 6.
The reason why it is located at the foot hanging part 7 is as follows.

The varistor element 4 and the lead wires 5, 5' are connected with solder dips to avoid the effects of heat, arc, etc. when the varistor element 4 is short-circuited. , the influence of solder can be avoided, and the mechanical force applied to the lead wires 5 and 5' can be absorbed by the foot sagging part 7, so that the influence on the overcurrent cutoff function part 8 can be kept to a minimum; Furthermore, if the current exceeds the interrupting ability of the overcurrent interrupting function section 8, a crack will occur in the foot sagging section 7, and mechanical disconnection can be expected.

Next, an embodiment of the overcurrent cutoff function section 8 will be described. FIG. 3 shows an example in which a small glass tube fuse is embedded in the foot sag 7. 5 is the lead wire, 9
1 is a fuse wire, and 10 is a cylindrical glass tube. In FIG. 4, the fuse wire 9 is directly soldered, welded, or mechanically pressure-bonded to the lead wire 5 without using a glass tube, and numeral 11 shows the soldered part as an example.

On the other hand, Fig. 5 A, B, and C do not use fuses,
This is an attempt to locally reduce the cross-sectional area of the lead wire 5 and cause it to melt in response to an overcurrent. Reference numeral 12 denotes a portion where the cross-sectional area of the lead wire 5 is locally reduced along the circumference or in a wedge shape.

As described above, the electronic component of the present invention can obtain the following effects by embedding an overcurrent interrupting function in the foot sagging portion of the insulating exterior.

(1) Operates in the event of a short circuit and prevents the accident from spreading.

(2) Provides an overcurrent interrupt function that is less susceptible to the effects of short-circuit breakdown, solder dip, and mechanical force from lead wires.

(3) Mechanical disconnection of the foot sag can be expected in response to excessive current.

Furthermore, by using a fuse for the overcurrent interrupting function, the interrupting current value can be set relatively accurately, and furthermore, it is possible to operate the fuse before short-circuit damage occurs.

Furthermore, by processing the lead wires to locally reduce the current carrying area, it is possible to provide an overcurrent cutoff function at a low cost and to obtain characteristics that are less susceptible to the influence of external heat.

[Brief explanation of the drawing]

Figure 1 is a front view of a conventional electronic component, Figure 2 is a front view of an embodiment of the electronic component of the present invention, and Figures 3 and 4 are examples of the overcurrent cutoff function of the electronic component. FIGS. 5A to 5C are front views showing other embodiments of the overcurrent cutoff function. 4... Ballista element body, 5, 5'... Lead wire,
6...Insulating exterior, 7...Coating foot sag,
8... Overcurrent cutoff function section, 9... Fuse wire, 1
0...Glass tube, 11...Solder, 12...Small cross-sectional area part.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) Lead wires are drawn out from the front and back of a component body, an insulating sheath is applied to this component body, and a foot sagging portion of the insulating sheath is provided at the part where the lead wire is drawn out from the component body. An electronic component having an overcurrent cutoff function built into the lead wire portion within the foot hanging portion. (2) The electronic component according to claim 1 of the utility model registration claim, which uses a fuse as an overcurrent interrupting function. (3) The electronic component according to claim 1, which is a utility model, and is constructed by providing a portion of the lead wire with a reduced effective cross-sectional area for current passage as an overcurrent cutoff function.