JPH07105813A - Thermal fuse - Google Patents

Abstract

PURPOSE:To surely prevent slight current from running after arc generated during operation is extinguished by adding a bending and forming process of lead wire's end part in a case. CONSTITUTION:A low melting point fusable metal piece 3 is bridged between the tip ends of a pair of parallel lead wires 2, 2 and a flux 4 is applied to the low melting point fusable metal piece 3. The flux applied low melting point fusable metal piece 3 is stored in a flat case 1 having a mouth 11 at one end through the mouth 11. After that, the mouth 11 is sealed with an adhesive 5 (e.g. epoxy resin). Further, the lead wires' tip ends 20 in the case are bent and formed so as to separate the lead wires' tip ends 20 and the flux applied low melting point fusable metal piece 3 from the inner face 10 of the case.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat case type alloy type temperature fuse.

[0002]

2. Description of the Related Art In an alloy type temperature fuse using a low melting point fusible alloy piece as a fuse element, when an electric device to be protected by the temperature fuse generates heat due to an overcurrent, the generated heat is generated. The fuse element is blown out by cutting off the power supply to the equipment to prevent abnormal heat generation or fire of the equipment.

The operation mechanism of the alloy type temperature fuse is such that the low melting point fusible alloy piece is melted by the heat generated by the overcurrent of the electric equipment, and this molten metal coexists with the flux already melted on the surface. The spheroidization is performed by energy, the molten metal is divided by the progress of the spheroidization, and when the arc generated at the initial stage of the division is no longer sustained due to the increase of the division distance, the current interruption is terminated.

As a conventional type of such an alloy type temperature fuse, as shown in (a) of FIG. 5 and (b) of FIG. 5 [a cross-sectional view taken along the line of (a) of FIG. A low melting point fusible metal piece 3'is bridged between the parallel lead wires 2 ', 2', and a flux 4'is applied to the low melting point fusible metal piece 3 ', and the flux is applied. Low melting point metal piece 3
It is known that 0 'is accommodated in a flat case 1'having an opening 11' at one end through the opening 11 'and the opening 11' is sealed with an adhesive 5 '.

As is well known, in the temperature fuse, since the circuit current is small and the failure current is low, it is used when it is difficult to perform the fusing operation of the current fuse due to the jule heat. To be done. Therefore, the operating voltage and current of the circuit to be protected by the temperature fuse are low, the energy of the arc during the operation of the temperature fuse is small, and the current fuse is low.
Unlike the case described above, the rupture of the case by the arc does not usually occur.

[0006]

Generally, in an electric device protected by a temperature fuse, a heat source based on a load current is used.
And is repeatedly subjected to heating within a temperature range lower than its operating temperature before operating the temperature fuse.

The temperature of this repetitive heating is determined by the rated energizing current of the equipment and therefore the heat resistance of the equipment, and the higher the heat resistance of the equipment, the higher the operating temperature of the temperature fuse is set. In the case of fuses, the above-mentioned repeated heating temperature may become considerably high and may exceed the melting point of the flux.

However, in the conventional flat case type alloy type temperature fuse, the lead wire comes into contact with one of the opposing flat surfaces in the case, and the tip of the lead wire is in contact. Flux application Since the low melting point fusible metal piece is close to one of the planes, if the flux is melted by repeated heating based on the heat cycle of the equipment, it will melt to the plane part in the case immediately below it. The flux transfer is unavoidable, and due to repeated heating, the transferred flux is adhered to the flat portion in the case, and under such a condition, it is generated during the operation of the temperature fuse.
The craters come into contact with the cohesive flux, forcing the carbonization of the flux.

Under such carbonization of the flux,
Since the carbonization path causes a low electrical resistance even after the fuse has been extinguished, it is difficult to reliably cut off the energization, and it is inevitable that a small amount of current continues to flow.

As described above, in the flat case type alloy type temperature fuse, the flux of the flux-coated low melting point soluble metal piece is melted due to the heat cycle of the equipment and is formed on the inner surface of the case. Adhesion, an alarm during the operation of the temperature fuse
This adhesion flux is carbonized due to the arc, and after the arc disappears, a slight current flows in this carbonization path, which may make it difficult to reliably cut off the current.

An object of the present invention is to provide a temperature fuse capable of easily solving the problem inherent to the flat case type alloy type temperature fuse.

[0012]

In the temperature fuse of the present invention, a low melting point soluble metal piece is bridged at a tip portion between a pair of parallel lead wires, and the low melting point soluble metal piece is connected to the low melting point soluble metal piece. In an alloy type temperature fuse in which a flux is applied, the flux-coated low melting point soluble metal piece is housed in the flat case having an opening at one end through the opening, and the opening is sealed with an adhesive. -The structure is characterized in that the lead wire tip and the flux-coated low melting point soluble metal piece are separated from the inner surface of the case by bending and forming the lead wire tip in the case. The voltage is 250 volts or less and the working current is 7 amps or less.

The structure of the present invention will be described below with reference to the drawings. 1 (a) is an explanatory view showing the alloy type temperature fuse of the present invention, and FIG. 1 (b) is a flow chart in FIG. 1 (a).
2B is a sectional view, and FIG. 1C is a sectional view taken along line HB in FIG. In FIGS. 1A to 1C, reference numeral 1 is a flat case having one end opened, and ceramics, plastic (for example, phenol resin) or the like can be used. 2 and 2 are a pair of parallel lead wires (usually copper wires are used), 3 is a low melting point as a fuse element bridged by welding at the tip between the lead wires 2 and 2. It is a soluble metal piece. Reference numeral 4 is a flux applied to the low melting point soluble metal piece 3, and this flux applying low melting point soluble metal piece 30
Is housed in the case 1 through the case opening 11 and the lead wire tip 20 and the flux-coated low melting point fusible metal piece 30 are formed on the inner surface of the case by bending the lead wire tip. Plane 1
Separated from zero. Reference numeral 5 denotes an adhesive that seals the opening 11 of the case 1. For example, an epoxy resin can be used.

2 (a) and 2 (b) [a sectional view taken along line (b) of FIG. 2] shows another embodiment of the present invention, in which the lead wire tip 20 is inclined. The lead wire tip portion 20 and the flux-coated low-melting point fusible metal piece 30 are formed by bending to form a space apart from the plane 10 of the inner surface of the case.

3 (a) and 3 (b) [a sectional view taken along line (b) of FIG. 3] shows another embodiment of the present invention, in which the lead wire tip portion 20 is Fold back the tip of the folded wire by abutting the tip of the folded back against the corner at the back of the case.
0 and the flux-applied low melting point fusible metal piece 30 are separated from the plane 10 of the inner surface of the case.

In the above embodiment, both lead wires are arranged on one side of both planes in the case. However, as shown in FIG. One lead wire 2 is arranged and the tip 20 of each lead wire 2 is bent to form the lead wire tip 20 and the flux-coated low melting point fusible metal piece 30 on the inner surface of the case. It may be separated from the plane 10. In each of the above embodiments, each plane 1 in the case
The distance between 0 and the flux melting low melting point metal piece 30 is
It is about 1 mm to 1.5 mm.

[0017]

Function: The equipment to be protected by the temperature fuse is
Even if the flux of the low melting point fusible metal piece is melted by being heated at a temperature higher than the flux and lower than the melting point of the low melting point fusible metal piece by thermal cycle, the molten flux does not cause "dag". Since the melted low melting point fusible metal piece and the case inner plane are sufficiently separated from each other, the molten flux is transferred to the case inner plane, Adhesion to the inner surface of the case due to repeated heating can be avoided.

In the temperature fuse, when the flux is melted together with the low melting point fusible metal piece, the molten metal is spheroidized by the surface energy together with the molten flux, and the spheroidization progresses and the spheroidization is performed. An arc occurs in the meantime. Even if this arc comes into contact with the inner surface of the case, since there is no adhesion of the flux at that portion, it is possible to avoid the generation of a conductive path due to the flux carbonization between the divisions. Therefore, the resistance between the divisions after the arc is extinguished can be sufficiently ensured, and the energization interruption can be completed. This can be confirmed by comparing the measurement results of the insulation resistance values after the operation of the following Examples and Comparative Examples.

[0019]

EXAMPLE In FIGS. 1A to 1C, the flat cable
As the case 1, a ceramic case having a vertical length (lead wire direction) of 8.5 mm, a horizontal width of 6.6 mm, and a flat space inside the case having a thickness of 2.7 mm is used. 2 has an outer diameter of 0.
7 mm copper wire is used, and the low melting point fusible metal piece 3 is a eutectic alloy having a melting point of 143 ° C. and an outer diameter of 0.5 mm.
For the flux 4, a rosin-based compound having a softening point of 70 ° C. is used, and further, the length L of the lead wire tip portion 20 is set to 2 mm,
The product of the example was manufactured by setting the distance h between each flat surface 10 in the case and the lead wire tip portion 20 to 1.0 mm.

With respect to this embodiment, the lead wire end portion was not bent and the lead wire in the case was attached to one of the planes in the case as shown in FIG. A comparative example product was manufactured in the same manner as the example product except that the portions were contacted over the entire length.

With respect to these example products and comparative example products (each of which has 20 samples), heating at 130 ° C. for 1 hour while continuing to apply a voltage of 275 V and 12 amps,
After cooling was repeated 10 times for 10 minutes, the temperature fuse was activated, and after the activation, the voltage was released and the resistance value between the lead wires was measured. Although it was 50 MΩ, it was 0.1 in the comparative example product.
One MΩ, two 0.2MΩ, the rest 2MΩ to 10M
It was Ω.

[0022]

The temperature fuse of the present invention is constructed as described above, and in the flat case type alloy temperature fuse, after the arc generated during operation disappears, the lead wire is removed. Since the resistance between them can be made sufficiently high, it is possible to reliably prevent a slight current from flowing after the arc disappears.

Thus, according to the present invention, a flat case type alloy type temperature fuse capable of surely completing energization interruption can be simply formed by adding a step of bending the lead wire tip. Can be provided to.

[Brief description of drawings]

1A is an explanatory view showing an embodiment of the present invention, FIG. 1B is a cross-sectional view taken along the line of FIG. 1A, and FIG. FIG. 3 is a cross-sectional view taken along the line 1- (I) of FIG.

2 (a) is an explanatory view showing an embodiment of the present invention different from the above, and FIG. 2 (b) is a flowchart in FIG. 2 (a).
FIG.

3 (a) is an explanatory view showing an embodiment of the present invention different from the above, and FIG. 3 (b) is a flowchart in FIG. 3 (a).
FIG.

FIG. 4 is an explanatory view showing another embodiment of the present invention different from the above.

5 (A) is an explanatory view showing a conventional example, and FIG. 5 (B) is a cross-sectional view taken along line (B) of FIG.

[Explanation of symbols]

 1 Case 10 Plane in 10 Case 11 Opening of Case 2 Lead Wire 20 Lead Wire Tip 3 Low Melting Melt Metal Piece 4 Flux 5 Adhesive

Claims (1)

[Claims] 1. A low melting point soluble metal piece is bridged at a tip portion between a pair of parallel lead wires, a flux is applied to the low melting point soluble metal piece, and the flux coating low melting point soluble metal piece is applied. In an alloy type temperature fuse in which a piece is housed in a flat case having an opening at one end through the opening, and the opening is sealed with an adhesive, bending of the lead wire tip portion in the case is performed. By the same lead
A temperature fuse characterized in that the wire end and the flux-coated low melting point metal piece are separated from the inner surface of the case.