JPS606982Y2 - electronic components - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement in an electronic component, such as a temperature fuse, in which an element is housed in a metal case and a lead wire is led out through an insulating plug from an open end of the metal case.

2. Description of the Related Art In order to maintain reliability in various electronic components, it is well known that elements are housed in a metal case, and lead wires are led out while being insulated from the metal case.

For example, in recent years, overtemperature rise prevention devices have been used from the viewpoint of the safety of electrical equipment, and in particular, non-resettable temperature fuses that use a temperature sensitive agent that melts at a specific temperature have been gaining popularity.

As shown in Fig. 1, a typical temperature fuse of this type includes a bottomed cylindrical metal case 1 made of a metal with good conductivity and good thermoelectricity such as copper, and a metal case 1 at the bottom of the metal case 1. The first lead wire 2 fixed by caulking, the elements housed in order in the metal case 1, that is, the temperature-sensitive agent 3 that melts at a specific temperature, the press plates 4 and 5, and the press plates 4 and 5 interposed in a compressed state. a strong compression spring 6 for closing the circuit, a movable contact 7 whose peripheral portion elastically engages with the inner wall surface of the metal case 1, and an insulating plug 8 made of ceramic or the like that closes the open end of the metal case 1. , a second lead wire 9 passing through the center hole of the insulating plug 8 , a large-diameter fixed contact 10 provided at the inner end of the second lead wire 9 , and a connection between the movable contact 7 and the insulating plug 8 . A weak compression spring 11 for opening the circuit is interposed in a compressed state between the two, and a sealing resin 12 made of epoxy resin or the like is adhered to the outer surface of the insulating plug 8.

In such a configuration, the temperature-sensitive agent 3 is solid at room temperature, and the elastic force of the strong compression spring 6 is blocked by the temperature-sensitive agent 3, so that the movable contact resists the elastic force of the weak compression spring 11. 7 is strongly pressed into contact with the fixed contact 10.

Therefore, the lead wires 2 and 9 are maintained in a conductive state through the lead wire 2 - metal case 1 - movable contact 7 - fixed contact 10 - lead wire 9 path.

When the ambient temperature rises abnormally and exceeds the melting point of the temperature sensitive agent 3, the temperature sensitive agent 3 melts.

Then, the blocking force of the temperature-sensitive agent 3 against the strong compression spring 6 disappears, and the strong compression spring 6 expands.

Accordingly, the elastic force of the strong compression spring 6 weakens, and as a result, the elastic force of the weak compression spring 11 exceeds the elastic force of the strong compression spring 6, the weak compression spring 11 expands, and the movable contact 7 separates from the fixed contact 10. As a result, the lead wires 2 and 9 become non-conductive.

FIG. 2 shows the state after this operation.

This type of temperature fuse can have a temperature fuse of any operating temperature with the same structure by using a temperature sensitive agent 3 with a predetermined melting temperature, and since it uses a metal case 1, it can operate quickly and Because it has the advantage of being reliable,
It is widely used in various fields.

In the temperature fuse of the above structure, the withstand voltage after operation is generally given by the distance between the fixed contact 10 and the weak compression spring 11 or the creepage distance l of the sealing resin 12 between the metal case 1 and the lead wire 9. .

Therefore, both the interval dimension and the creepage distance l are set to be sufficiently large.

Although the distance between the fixed contact 10 and the weak compression spring 11 is smaller than the creepage distance of the sealing resin between the metal case 1 and the lead wire 9, this type of temperature switch cannot be assembled and sealed in dry gas. Since it is sealed with the metal case 1, the withstand voltage can be made sufficiently high.

On the other hand, even if the latter creepage distance l is large, dew condensation may form on the surface of the sealing resin 2 depending on the environment in which the temperature fuse is used, so the withstand pressure tends to be low.

However, as is clear from FIG. 1, since the lead wire 9 has a large-diameter fixed contact 10 formed at its inner end,
The fixed contact 10 acts as a stopper and can resist the pulling force F1 directed outward (rightward in the drawing), but resists the pushing force F2 directed inward (leftward in the drawing). small.

Therefore, as shown in FIG. 3, if the amount of sealing resin 12 deposited is small, the resistance force becomes smaller and smaller, and if the lead wire 9 moves inward due to the inward pressing force F2, The fixed contact 10 contacts the movable contact 7 and becomes closed again, and even if the fixed contact 10 does not contact the movable contact 7, the two become extremely close and the withstand voltage decreases.
Reliability will be low.

In order to prevent such inward movement of the lead wire 9, it is conceivable to form a bulge by machining at the outer base of the insulating plug 8 of the lead wire 9. Then, in a bending test or a torsion test of the lead wire 9, there is a problem that the test stress is concentrated on the bulged portion and the bending strength and torsion strength are reduced.

Furthermore, when the amount of the sealing resin 12 deposited is small, the creepage distance l also becomes small.

On the other hand, when the amount of the sealing resin 12 is increased, the sealing resin 1
2 flows to the circumferential surface of the metal case 1 and adheres thereto, resulting in a problem that the appearance is likely to be poor.

This invention was proposed to solve the above-mentioned problems, and one embodiment thereof will be described below with reference to the drawings.

4 is similar to FIG. 1 except for the following points, and the same or corresponding parts as in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted.

First, the difference is that a bulge 13 is formed at the outer root portion of the insulating plug 8 of the lead wire 9.

This bulge 13 is formed by mechanically crushing a part of the lead wire 9, as shown in FIGS. 5A and 5H.

After coating the outer surface of the insulating plug 8 with a required amount of sealing resin 12, an insulating cylinder 14 made of ceramic or the like is inserted into the lead wire 9 until it abuts the bulge 13, and the sealing resin 12 is applied to the outer surface of the insulating plug 8. The difference is that it is solidified.

According to the above configuration, since the bulge 13 is formed at the outer root portion of the insulating plug 8 of the lead wire 9, the lead wire 9
Even if an inward stress F2 is applied, the bulging portion 13 prevents the lead wire 9 from moving inward, and the movable contact 7 and the fixed contact 10 do not come into contact or come close to each other after operation. All will be gone.

In addition, since the insulating cylinder 14 is inserted into the lead wire 9,
Even if bending stress or twisting stress is applied to the lead wire 9, these stresses will not be concentrated on the bulge portion 13, and the bending strength or twisting strength will be improved.

Furthermore, the creepage distance between the metal case 1 and the lead wire 9 is significantly increased by the insulating cylinder 14, and since the insulating cylinder 14 is positioned by the bulge 13, the creepage distance is constant and the sealing resin 12 can also be prevented from protruding onto the peripheral surface of the metal case 1.

Although this invention is particularly effective in the above-mentioned temperature fuse, it can also be applied to other electronic components.

According to this idea x, as described above, it is possible to prevent the lead wire from moving inward, and a sufficient and constant creepage distance can be obtained, so that a highly reliable electronic component can be provided.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a temperature fuse as an example of an electronic component that is the background of this invention, Fig. 2 is a cross-sectional view showing the state of the temperature fuse in Fig. 1 after operation, and Fig. 3 is a cross-sectional view of the temperature fuse in Fig. 1. 4 is a cross-sectional view of the temperature fuse which is an embodiment of the electronic component of this invention, FIG. 5A is a front view of the bulge 13, and FIG. Figure 5A
FIG. 2 is a sectional view taken along line BB of FIG. 1...Metal case, 2,9...Lead wire, 3...Temperature sensitive agent, 6...High pressure cotton spring, 7...・Movable contact, 8...Insulating plug, 10...Fixed contact, 11...Weak compression spring, 12...Sealing resin, 13... ...Bulging part, 14...Insulating cylinder.

Claims (1)

[Scope of utility model registration request] An element is housed in a metal case, and a lead wire is led out from an open end of the metal case through an insulating plug, and a bulge is formed at the outer base of the insulating plug of the lead wire, and An electronic component characterized in that an insulating cylindrical body inserted up to the position of the bulge of the wire is fixed to the insulating plug and the lead wire with a sealing resin.