JP2524878B2 - Alloy type temperature fuse - Google Patents

Description

TECHNICAL FIELD The present invention relates to an alloy type thermal fuse.

(Prior Art) In an alloy type thermal fuse, a low melting point fusible alloy is used for a fuse element, and various types are known. FIG. 1 shows a linear type, in which a linear low melting point fusible alloy piece 2 is welded between lead wires 1 and 1 which face each other on a straight line, and a flux is applied onto the low melting point fusible alloy piece 2.
A heat resistant insulating cylinder 4 (for example, a ceramic cylinder) is inserted on the low melting point fusible alloy piece, and each end of the insulating cylinder 4 and the lead wire 1,
The space between 1 and 1 is sealed by adhesives 5 and 5 (epoxy resin).

The thermal fuse is attached to the part of the electrical equipment to be protected and where heat generation is easily detected. When the electric equipment to be protected generates heat due to overcurrent, the heat generation heats the thermal fuse to melt the low melting point fusible alloy piece, and the molten alloy is divided, and the electric equipment is energized. It is shut off and the equipment is prevented from overheating.

The mechanism of fragmentation of the molten alloy is that the molten alloy tries to be spheroidized due to its surface tension, and the spheroidization causes fragmentation. In this case, if an oxide film exists on the surface of the low melting point fusible alloy piece before melting, the oxide film forms an insoluble hard outer skin, so that spheroidizing is difficult even if the inside of the outer skin is in a molten state. is there. Therefore, the flux on the surface of the low melting point fusible alloy has a function of preventing the formation of such an oxide film. This flux usually contains active rosin, and in addition, an activator such as diethylamine hydrochloride is added to enhance the activity. , Has a function of rapidly reacting with an oxide to solubilize the oxide and accelerate the above spheroidization.

(Problems to be Solved) The ideal state of the spheroidization of the molten alloy is that the molten alloy is completely spheroidized with the tips of the lead wires 1 and 1 as cores, as shown in FIG. is there. The interval between the spherical bodies has a significant effect on the withstand voltage after the division, and if the spherical shape is incomplete and the interval is narrow, re-conduction is likely to occur. In particular, when the load is inductive, there is induction of an excessive transient voltage due to a sharp change in magnetic flux when the power is cut off.
The probability of re-conduction is high.

This withstand voltage depends on the difficulty of spheroidization of the molten alloy, and therefore, it is clear that the activation force of the flux is involved in the withstand voltage, but the increase in the activation force of the flux alone will increase the withstand voltage. Molten alloy that cannot be effectively improved,
It is considered that the surface energy of the molten flux and the insulating property of the molten flux are also involved, and it is difficult to select the flux unconditionally.

In the present applicant, an alloy characterized in that a fuse element is applied with a rosin having a fatty acid amide having 15 to 20 carbon atoms and optionally an activator, from a low melting point melting alloy having a melting point of 90 ° C. or higher. A type thermal fuse has already been proposed (Japanese Patent Publication No. 7-60627). In this alloy type thermal fuse, with respect to a low melting point fusible alloy with a melting point of 90 ° C or more, the addition of fatty acid amide can significantly improve the withstand voltage after the operation of the alloy type thermal fuse. 90 ° C
With respect to the above-mentioned low melting point soluble alloy, there is no effect in improving the withstand voltage property, or rather, the addition of the fatty acid amide causes a decrease in withstand voltage property.

Therefore, it is required to improve the withstand voltage after the operation of an alloy type thermal fuse having a low melting point fusible alloy with a melting point of 90 ° C or less as a fuse element. The improvement is not easy due to the complicated factors.

However, in the present inventor, unexpectedly, if a straight chain saturated fatty acid having 12 to 24 carbon atoms is added to the flux, the alloy type thermal fuse having a low melting point fusible alloy having a melting point of 98 ° C. as a fuse element will be used. As well as melting point 57 ℃
Moreover, it has been found that the withstand voltage can be dramatically improved even for an alloy type thermal fuse having a low melting point fusible alloy having a melting point of 71 ° C. as a fuse element.

The object of the present invention is to make the operating temperature 10
It is to improve the withstand voltage after the operation of the alloy type thermal fuse of 0 ° C. or less.

(Means for Solving the Problems) The alloy-type thermal fuse according to the present invention has a melting point of 100 ° C., which is obtained by adding a rosin containing a linear saturated fatty acid having 12 to 24 carbon atoms and an activator.
The composition is characterized by being applied to a fuse element made of the following low melting point molten alloy, and the addition of an activator can be omitted.

Examples of the straight chain saturated fatty acid having 12 to 24 carbon atoms used in the present invention include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid and lignoceric acid.

As the rosin, natural rosin, modified rosin (for example, hydrogenated rosin, disproportionated rosin, polymerized rosin) and purified rosins thereof can be used.

Diethylamine hydrochloride, hydrobromide and the like can be used as the activator.

The usual compounding ratio of the flux used in the present invention is rosin: 90 to 60 parts (parts by weight, hereinafter the same), carbon number 1
2 to 24 linear saturated fatty acids; 10 to 40 parts, activator; 0 to 3 parts, and if the amount of the linear saturated fatty acids is 10 parts or less, it is difficult to satisfactorily achieve the effect of improving the withstand voltage. Above the above range, the internal pressure generated due to the vaporization of the flux due to the arc heat during the operation of the thermal fuse becomes excessively large, and the scattering range of the molten alloy becomes extremely wide.

The present invention is directed to an alloy type thermal fuse having a melting point of a low melting point fusible alloy piece of 100 ° C. or less as a fuse element, and as such a low melting point fusible alloy, Bi; 33 parts, Pb; 18.
, Sn; 9 parts, Cd; 7 parts, In; 33 parts alloy (solidus temperature; 5
6 ℃, liquidus temperature; 59 ℃), Bi; 50 parts, Pb; 25 parts, Sn; 12.5
, Cd; alloy consisting of 12.5 parts (solidus temperature; 70 ℃, liquidus temperature; 72 ℃), Bi; 50 parts, Pb; 31 parts, Sn; alloy consisting of 19 parts (solidus temperature; 95 ℃, liquidus temperature; 95 ℃) etc. can be used.

INDUSTRIAL APPLICABILITY The present invention can be applied to any type of alloy-type thermal fuse without limitation, a linear type, a low melting point fusible alloy piece is bridged to the tips of mutually parallel lead wires, and a flux is applied onto the low melting point fusible alloy piece. Which is coated with a curable resin by dipping, a pair of film electrodes is provided on one surface of the insulating substrate,
A lead wire is connected to each electrode, a low melting point fusible alloy piece is bridged between these electrodes, flux is applied on the low melting point fusible alloy piece, and one surface of the insulating substrate is covered with an insulating layer. Applicable to (board type thermal fuse) etc.

Regarding the dimensions of the alloy type thermal fuse, for example, in the case of a linear type thermal fuse, the lead conductor diameter: 0.5 to 1.0 mm, the linear fusible alloy diameter: 0.5 to 1.0 mm, the linear fusible alloy length: 2.0 to 5 .
0 mm, thickness of flux layer: 0.05 to 1.0 mm, outer diameter of insulating cylinder: 1.0
~ 3.0mm, insulation tube length: 5.0 ~ 12.0mm. The amount of the above flux is preferably 0.5 to 3.5 times the amount of the low melting point soluble alloy.

(Description of Example) Hereinafter, an example of the present invention will be described.

Examples 1 and 2 The type of thermal fuse used is a linear type. Dimensions are: lead wire diameter: 0.6 mm, low melting point fusible alloy piece diameter: 0.6 mm, low melting point fusible alloy piece length: 4.0 mm, ceramic insulation cylinder inner diameter:
1.5mm, ceramics insulation cylinder outer diameter: 2.5mm, insulation cylinder length: 9.
It is 0 mm. An epoxy resin was used as the sealing resin. For the low melting point alloy, Bi: 33 parts, Pb: 18 parts, Sn: 9 parts, Cd: 7 parts, I
n; alloy consisting of 33 parts (solidus temperature; 56 ° C, liquidus temperature; 59
C) was used. As the flux, in Example 1, polymerized rosin: 65 parts, myristic acid: 35 parts, diethylamine hydrochloride: 1 part, and in Example 2, polymerized rosin: 8 parts
0 part, myristic acid: 20 parts, diethylamine hydrochloride: 1 part were used, respectively. In any of the examples, the flux amount was tripled with respect to the low melting point soluble alloy amount.

The products of these Examples were heated to 62 ° C. to melt and separate the low melting point alloy pieces, and then the withstand voltage between both lead wires was measured. In Example 1, 2.1 Kv, Example 2 Then 2.2
It was Kv.

Examples 3 and 4 As compared with Examples 1 and 2, Bi; 5 was added to the low melting point fusible alloy pieces.
Same as Examples 1 and 2 except that an alloy consisting of 0 part, Pb; 25 parts, Sn; 12.5 parts, Cd; 12.5 parts (solidus temperature; 70 ° C, liquidus temperature; 72 ° C) was used. did.

The products of these Examples were heated to 75 ° C. to melt and separate the low melting point alloy pieces, and then the withstand voltage between both lead wires was measured. In Example 3, 2.3 Kv, Example 4 Then 2.4
It was Kv.

Examples 5 and 6 In contrast to Examples 1 and 2, Bi; 5 was added to the low melting point fusible alloy pieces.
Alloy consisting of 0 part, Pb; 31 parts, Sn; 19 parts (solidus temperature: 95 ° C,
Liquidus temperature; 95 ° C.), except Examples 1 and 2
Same as.

The products of these Examples were heated to 98 ° C. to melt and separate the low melting point fusible alloy pieces, and the withstand voltage between both lead wires was measured. In Example 5, 2.2 Kv, Example 6 Then 2.4
It was Kv.

Comparative Example 1 The same as Example 1 or 2 except that 100 parts of natural rosin and 1 part of diethylamine hydrochloride were used as the flux.

This comparative example product was heated to 62 ° C. to melt and separate the low melting point fusible alloy pieces, and the withstand voltage between both lead wires was measured and found to be 1.0 Kv.

Comparative Example 2 The same as Example 3 or 4 except that 100 parts of natural rosin and 1 part of diethylamine hydrochloride were used as the flux.

This comparative example product was heated to 75 ° C. to melt and separate the low melting point fusible alloy piece, and the withstand voltage between both lead wires was measured and found to be 1.3 Kv.

Comparative Example 3 The same as Example 5 or 6 except that 100 parts of natural rosin and 1 part of diethylamine hydrochloride were used as the flux.

The comparative example product was heated to 98 ° C. to melt and separate the low melting point fusible alloy piece, and the withstand voltage between both lead wires was measured and found to be 1.2 Kv.

From the comparison of the withstand voltage values of the above-mentioned Example and Comparative Example, as is apparent, by adding linear saturated fatty acid having 12 to 24 carbon atoms to the flux, the withstand voltage after the operation of the alloy type thermal fuse was confirmed. It is clear that the property can be sufficiently improved.

(Effects of the Invention) As described above, according to the alloy type thermal fuse according to the present invention, the withstand voltage property of the alloy type thermal fuse having an operating temperature of 100 ° C. or less can be improved, so that an excessive transient voltage is generated when the energization is cut off. It is useful for generating inductive load circuits.
Further, the space between the lead wires can be reduced to downsize the alloy type thermal fuse.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a linear thermal fuse, and FIG. 2 is an explanatory diagram showing an operating state of the thermal fuse. 2 ... Low melting point fusible alloy, 3 ... Flux.

Claims (2)

(57) [Claims] 1. An alloy-type thermal fuse, characterized in that a rosin to which a straight chain saturated fatty acid having 12 to 24 carbon atoms is added is applied to a fuse element made of a low melting point fusible alloy having a melting point of 100 ° C. or less. 2. An alloy type thermal fuse characterized in that a rosin containing a straight chain saturated fatty acid having 12 to 24 carbon atoms and an activator is applied to a fuse element made of a low melting point fusible alloy having a melting point of 100 ° C. or less. .