JPH012238A - electrical fuse - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) This invention comprises a molten conductor in a particularly cylindrical casing whose ends are sealed with caps or lids, a lead wire starting from both caps, and a synthetic resin. The present invention relates to an electric fuse as a device protection fuse having a covering part made of aluminum.

(Prior art/Problems to be solved by the invention) The resin-coated fuse of the above type is disclosed in US Pat. No. 4,385,281.
No. 4,460,887. There, the syfuse is coated with a synthetic resin either by applying a synthetic resin powder and heating or by a synthetic resin dip coating method.

In either case, a fuse body coating is formed that roughly corresponds to the fuse contour. Since the bonding area between the cap and the lead wire is also covered, the lead wire will not easily break like in the case of an uncoated fuse even if handled carelessly, but the bonding strength between the lead wire and the cap is still strong. cannot be fundamentally enhanced. Additionally, the outer shape of one known covered fuse has a throat or radius that precludes printing or other fuse markings on the synthetic resin outer circumferential surface. This coating method also does not allow for strictly uniform coating, resulting in variations in the shape of the series products. Additionally, the selection of synthetic resins should not only provide the necessary electrical insulation properties, but also provide a coating that is permanently bonded to the casing, cap, and adjacent leads.

The invention therefore aims at eliminating or at least essentially reducing the aforementioned disadvantages.

(Means for Solving the Problem) According to the present invention, the casing, including the adjacent portions of the cap and the lead wire, has a free outer shape that is independent of the shape formed by the casing, the cap, and the lead wire. This is achieved by embedding it in a shaped synthetic resin body.

(Function) In contrast to the prior art, the molded body is formed from a synthetic resin in which the fuse and the adjacent lead wire sections are completely embedded; thus, in contrast to the results and possibilities of coating methods, the synthetic The resin body can be of any desired or most convenient shape for each application, no longer common to the shape of the embedded fuse.

The fuse according to the invention has excellent mechanical strength. Its breaking capacity is considerably higher than that of an uncoated fuse, and is even stronger than that of a fuse simply coated with synthetic resin. The trap is therefore designed to virtually preclude explosion or rupture of the fuse even under very high short circuit loads.

The bond strength between the cap and the adjacent lead portion is also substantially improved by the present invention.

This lead wire portion is also embedded in the synthetic resin body and cannot be removed from the cap. Even when twisted or bent, or under high tensile stress, the lead wires will at most tear or break outside the plastic body.

In contrast to coating methods, synthetic resin bodies can easily be constructed substantially longer than the length corresponding to the actual fuse, if this is desired.

This means, for example, that it can be much longer than the cap.

The location of the fusible conductor within the tubular casing has no bearing on the embedding of the fuse and depends primarily on the respective fuse type and the method utilized for attaching the fusible conductor.

Fuses are typically mass-produced items, and therefore embedding them in synthetic resin bodies can be carried out very inexpensively by injection molding of suitable synthetic resins. After manufacturing the fuse body, the steps required for embedding it in synthetic resin can easily be fully automated.

Since the embedding is carried out in a suitable mold, each synthetic resin body has a strictly defined shape, the dimensions of which are very precisely reproducible, in contrast to dip-coating or coating methods.

The synthetic resin body desirably seals around and is in tight contact with the casing, cap and leads.

Molding of synthetic resin bodySpecial liquid synthetic resin is supplied under high pressure, so that there is no possibility of air being mixed in, for example, in the transition area between the cap and the casing.

Preferably, the synthetic resin body is cylindrical, and the lead wire protrudes from its end face.

Printing on the cylindrical outer circumferential surface can be carried out very simply with both annular and axial markings.

If necessary, the longitudinally elongated synthetic resin body can be easily manufactured to have a polygonal cross section.

The synthetic resin body is preferably manufactured from a thermoplastic resin.

Suitable materials for this purpose are special polyamide 6 (PA6), polyamide 1s6 (PA61), polyphenylene oxide (PP0), polyethylene terephthalate (PETP), and polyphenylsulfide (PP8).

As all described in part above, the synthetic resin body is preferably produced by injecting liquid synthetic resin around the casing and other parts in a mold that receives the completed casing, including the cap and the leads. formed by. After the synthetic resin has hardened, the embedded fuse is removed from the mold.

The above advantage is that the synthetic resin body is configured in a rectangular parallelepiped shape, and the lead wires are connected to opposite sides of the synthetic resin body or both sides of the resin body.
This also applies to variants of the invention drawn out from the surface. This results in a component which can be used in radial construction technology or by bending the connecting legs and can be used as an SMD component if the lead wires are configured accordingly.

(Example ) The present invention will be described in detail below with reference to the drawings.

A cap 2 having a solder intermediate layer 7 at both ends of a small tubular casing 1 usually made of glass or ceramic.
Each is sealed.

A fusible conductor (not shown) extends diagonally or axially through the free space inside the casing 1, and its ends are electrically connected to the cap 2 through the solder intermediate layer 7, respectively. Adjacent portions 3 of lead wires 4 are conductively fixed to the outer end surface of metal cap 2 (2). Solder intermediate layer 7 is made of, for example, silver-lead solder (965% lead, 5% Sengo; melting point 221°C).
) or zinc solder (95% zinc, 5% antimony; melting point 236-243°C).

The aforementioned fuse is embedded in a solid synthetic resin body 5 to which a portion 5 of the lead wire 4 adjacent to the cap 2 is also connected, as shown in the drawings.

For the production of the synthetic resin body 5, thermoplastic resins of the type described above are used. After the manufacture of the fuse consisting of parts 1, 2, 3, 4.7, the fuse is placed in a fully automated manufacturing process into a mold which gives it the desired shape of the plastic body. After the mold is closed, heated liquid synthetic resin is supplied to the mold through the sprue under appropriate pressure, and the synthetic resin is completely injected around the fuse to fill the mold.

After the synthetic resin has hardened, the mold is automatically opened, and the fuse that has been embedded in the formed synthetic resin body 5 is taken out and sent to a regular quality control department.

In this case, the portion 3 of the lead wire 4 starting from the end face 6 of the cylindrical synthetic resin body 5 is only firmly joined to the synthetic resin body 5, and therefore cannot be removed from the cap 2.

Fuses produced in this way are used in particular as equipment protection fuses.

In the embodiment shown in FIG. 3, the fuse is embedded in a rectangular parallelepiped synthetic resin body 5 together with a small tubular casing 1, a cap 2 and a lead wire 4 originating from the cap 1. Lead wire 4
Depending on the configuration, especially into an overhang, the embedded fuse can be used as a radial part (see FIG. 4) or as an 8MD part (see FIG. 5).

(Effects of the Invention) According to the structure of the present invention, since the lead gland portion is also embedded in the synthetic resin body, the bonding strength between the lead wire and the cap is increased, the mechanical strength of the fuse is improved, and the fuse It can increase the interruption capacity and eliminate fuse rupture under high short-circuit loads.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a fuse embedded in a synthetic resin. FIG. 2 is a front view of the buried fuse shown in FIG. 1. FIG. 3 is a perspective view of the second embodiment. 4 and 5 are partial views showing the form of the lead wire in FIG. 3. FIG. 1...Casing, 2...Cap, 3...
Part 4...Lead wire, 5...Synthetic resin body. Patent applicant: Wickmann Querke GmbH
l 4

Claims (7)

[Claims] (1) In a fuse, especially a device protection fuse, which has a fusible conductor in a cylindrical tube sealed at both ends with a cap or lid, lead wires starting from both caps, and a synthetic resin covering part, the casing (1) includes the cap (2) and the adjacent portion (3) of the lead wire (4);
An electrical fuse characterized in that it is embedded in a synthetic resin body (5) whose outer shape is substantially independent of the shape formed by a casing (1), a cap (2), and a lead wire (4). (2) The electricity according to claim 1, characterized in that the synthetic resin body (5) seals around the casing (1), the cap (2), and the lead wire (4) and contacts them tightly. fuse. (3) The synthetic resin body (5) is cylindrical, and its end surface (6
3. Electrical fuse according to claim 1, characterized in that the exposed part (6) of the lead wire (4) starts from ). (4) The electrical fuse according to claim 1 or 2, wherein the synthetic resin body (5) has a polygonal cross section. (5) The synthetic resin body (5) is configured in a rectangular parallelepiped shape,
An electrical fuse according to claim 1 or 2, characterized in that the lead wires (4) are drawn out from opposite sides or both sides of the synthetic resin body (5). (6) The electrical fuse according to any one of claims 1 to 5, wherein the synthetic resin body (5) is made of thermoplastic resin. (7) The synthetic resin body (5) is connected to the cap (2) and the part (5).
) and the completed casing (1) including the lead wire (4)
) is formed in a mold receiving the casing (1) and other parts by injecting a liquid synthetic resin around the casing (1) and other parts. An electrical fuse as described in any of the above.