JP2862316B2 - Thermal fuse circuit board with protective case - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is a function of preventing damage to a thermal fuse circuit of an enameled planar resistance circuit board used as a control board of an air conditioner for an automobile and preventing repair after a fuse is activated. The present invention relates to a thermal fuse circuit board with a protective case having:

[Prior art] Conventionally, in an insulating substrate for control used in an air conditioner for an automobile, a resistance circuit is changed due to abnormal heat generation during use and the intended control function is not exhibited. For the purpose of preventing such a situation, a fuse for protecting the circuit is provided.

However, most of the conventionally proposed fuses have a method in which one end of a wire or a leaf spring is fixed with a low-melting metal, so that there is a large variation in operating temperature, which is preferable as a function of the original intended fuse. It could not be said. Therefore, the present inventors previously divided the enameled resistor circuit board so that if the temperature became higher than a predetermined temperature due to abnormal heat generation or the like in the enameled resistor circuit board excellent in heat dissipation and mechanical strength, the fuse would operate correctly. It is proposed to use the enameled resistance circuit board with temperature fuse formed by precisely printing and sintering a low melting point metal to a predetermined shape thickness and area between the circuits as a control board of an air conditioner for automobiles. The problem was solved.

[Problems to be solved by the invention]

However, the enameled substrate with a fuse circuit proposed earlier by the present inventors is a very excellent operating characteristic of the thermal fuse, but the low melting point metal forming the fuse is relatively soft, Because it is formed in a thin layer,
In some cases, the device does not operate at a predetermined temperature due to abrasion caused by vibration during packing or transportation, or abrasion when the device is mounted on a device, and causes malfunction.

Also, if the thermal fuse is exposed in this way, if the thermal fuse is activated for any reason, it may be erroneously repaired by service personnel or general users. There is a possibility that the intended function of the fuse will not be exhibited.

The present invention prevents damage caused by vibrations during packing and transportation in such an enameled circuit board with a thermal fuse, and abrasion when mounted on a device.
In general, an object of the present invention is to provide an enameled circuit board with a thermal fuse, which prevents erroneous repair by a user and has precise and accurate operating characteristics intended for the intended purpose.

[Means for solving the problem]

According to the present invention, a protective case made of a metal plate is provided on a thermal fuse formed on an enameled substrate so as to cover the fuse, and a hole having an outer diameter fitted into a mounting hole on the enameled substrate is protruded from the metal case by punching. This is a thermal fuse circuit board in which a metal case formed by punching so as to generate a portion (burr) and forming a protruding portion by punching is attached by caulking the protruding portion.

As the heat-resistant material, a metal plate such as an aluminum plate, a heat-resistant resin (engineering plastics), or the like is preferable.

FIG. 1 is a perspective view in which a protective case 1 of the present invention is attached to an enamel substrate 10.

After forming the resistance circuit layer 5 on the enamel substrate 10, the fuse 4 is formed on the substrate on which the overglaze layer 7 has been formed except for the fuse portion, and an aluminum plate, a heat-resistant resin, etc. A protective case 1 made of a heat-resistant material is attached.

In the enamel substrate 10, the mounting hole 3 is formed in the metal core 9 in advance, and the enamel layer is formed and insulated to the inner surface of the hole when enameling the enamel. Hole diameter is 1 after glaze
About 2 mm is preferable. FIG. 1-1 is a detailed view in which a fuse 4 is attached to an end of a resistance circuit 5 via a conductor circuit 6, and FIG.

A hole having the same diameter as the mounting hole 3 on the enamel substrate is formed in the protective case 1 and mounted with a mounting tool 2 such as an eyelet.

When a metal plate made of aluminum or the like is used for the protective case 1, a hole slightly smaller than the diameter of the mounting hole is formed in the flat surface of the metal plate, and a punch-out portion (burr) is formed on the back surface of the metal plate. And thereby caulking.

FIG. 3 is a cross-sectional view in which a hole is formed in a metal plate so as to generate a protruding portion by punching, and a protection case is attached by caulking the protruding portion as shown in FIG.

FIG. 2 is a sectional view showing another embodiment in which the protective case 1 of the present invention is attached to an enamel board.

That is, the protection case is not mounted so as to straddle the resistance circuit layer, but is mounted in a direction perpendicular to the protection case.
Since there is the overglaze layer 7, it is insulated from the resistance circuit.

The conductor circuit layer 6 provided on the enamel substrate and the protective case 1 are insulated by an overglaze layer 7 provided on the conductor circuit.

In addition, short circuit of the resistor circuit can be prevented by using an insulating heat-resistant resin as a material of the protective case.

FIG. 2 is a sectional view of the mounting hole 3 where the protective case is mounted. Therefore, the resistance circuit layer does not come out on the cross section, and is indicated by a dotted line.

In this sense, the fuse 4 does not come out on the cross section,
Although only the overglaze layer 7 should appear in the cross section,
Since the cross section becomes complicated, only this portion is cut away, and the fuse 4 portion is shown by a dotted line.

1 and 2, 1 is a protective case, 2 is a fixture, 4
Denotes a fuse, 5 denotes a resistance circuit layer, 6 and 7 denote overglaze layers, 8 denotes an enamel layer, and 9 denotes a metal core.

The height of the convex portion of the protective case 1 is 1.0 to 5.0 mm as an inner dimension from the substrate surface to the inner surface of the case. If this dimension is smaller than 1.0 mm, the inner surface of the case may come into contact with the fuse 4. If this dimension is larger than 5.0 mm, the protective case 1 may become an obstacle during the packaging and transportation of the substrate, and may cause the protective case 1 to fall off, which is not preferable.

Further, in order not to affect the operation of the fuse 4, a structure as shown in FIG. 1 in which no wall is provided at both ends of the fuse 4 connected to the resistance circuit is preferable.

The area of the fuse 4 is usually about 2.5 to 4.0 × 5.0 mm, whereas the area of the projection of the protective case 1 covering the fuse 4 is about 8 × 15 mm, and the fuse 4 is located at the center thereof. Preferably, it is attached.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples, but it is needless to say that the present invention is not limited to these Examples.

FIG. 1 will be described. Two holes for attaching the protective case 1 are previously formed in a metal core having a thickness of 0.6 mm, and the enamel is applied to the inner surface of the hole when enameling the enamel. After baking, the hole diameter was 1.6 mm. A resistive circuit layer 5 and a conductive circuit layer 6 were formed on the fired substrate at a thickness of 15 μm and a width of 4.0 mm.
And the fuse portion separates the conductor circuit layer 6 so as to form both ends. Further, the entire substrate except the fuse portion including the resistance circuit layer 5 is covered with the overglaze layer 7. The fuse area was 4.0 mm x 5.0 mm. Protective case 1
Is made of aluminum plate and the area covering the fuse is 8.0mm x 1
5.0 mm. In the aluminum case, two holes having the same outer diameter as the inner diameter of the mounting hole 3 on the enamel board are formed so as to form a burr so that the outer diameter of the protruding portion becomes 1.6 mm by punching. The part was attached to the enamel substrate by caulking. The height inside the aluminum case was 4.0 mm.

〔The invention's effect〕

By attaching the protective case of the structure of the present invention,
Repair after fuse operation is virtually impossible, and a strong protective case prevents damage due to abrasion during packaging, transportation, storage or assembling into equipment. It has become possible to obtain operating characteristics.

[Brief description of the drawings]

FIG. 1A is a perspective view in which the protective case of the present invention is attached to an enamel substrate. FIG. 1B is a detailed view of a portion where the fuse 4 is constructed by sandwiching the conductor circuit layer 6 between the left and right resistance circuit layers 5 in FIG. FIG. 1C is a detailed view showing a mounting cross section of a mounting tool 2 for fixing the protective case 1 of FIG. 1A. FIG. 2 is a sectional view of another embodiment in which the protective case of the present invention is attached to an enamel substrate. FIG. 3 shows a view in which a hole is formed in the protective metal case so as to form a projection (burr) by punching. FIG. 4 is a cross-sectional view of a view in which a metal case having a projecting portion formed by punching is attached by caulking the projecting portion.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kiyoshi Yajima 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Electric Wire Co., Ltd. (72) Inventor Masanori Ito 1-1-5-1 Kiba, Koto-ku, Tokyo Fujikura Inside Electric Wire Co., Ltd. (72) Inventor Kenichi Uruga 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Electric Wire Co., Ltd. (72) Inventor Okuyama, etc. Inside 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Nobutaka Yamamoto 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonic Co., Ltd. (72) Inventor Hisaga Hirabayashi 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonic Corporation (72) Inventor Jun Ichikawa 2--11-22 Shimozato, Higashikurume-shi, Tokyo Inside the Tanashi Plant of Kowa Seisakusho Co., Ltd. (56) References Japanese Patent Laid-Open No. Sho 50-30042 (JP, A) 59-159847 (JP, U) (58 ) investigated the field (Int.Cl. ^6, DB name) H01H 37/76

Claims (1)

(57) [Claims] 1. A protective case made of a metal plate is provided on a thermal fuse formed on an enamel substrate so as to cover the fuse.
A hole having an outer diameter that fits into the mounting hole on the enamel board is formed in the metal case so as to form a projecting portion (burr) by punching, and the metal case having the projecting portion formed by punching is fixed to the metal case. Thermal fuse circuit board that is mounted by mounting.