JPS598933B2 - temperature fuse - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal fuse that operates safely even when an overcurrent flows.

Conventional insulated sealed thermal fuses using fusible alloys and fluxes are: 1. It is an insulated type.

2. No mounting directionality.

3. Operation is reliable. It has advantages such as transformer,
It can be wound into the coils of motors, etc., making it extremely useful in practice.

However, when this type of thermal fuse fuses due to an overcurrent exceeding the rated current, an arc occurs, and 1. Flux burns.

2. The fusible alloy paperizes and adheres to the inside of the container, resulting in poor insulation.

3. There were drawbacks such as the container being damaged due to an increase in internal pressure.

The present inventors have previously provided a thermal fuse that improves this drawback by making the lead wire portion thinner and having a current fusing function.

(Utility Application No. 50-162072).

In this case, if an overcurrent flows when the ambient temperature is low, the current will melt at the thinner part of the lead wire and it will operate reliably.
If an overcurrent flows while the ambient temperature is rising close to the melting temperature of the fusible alloy, the fusible alloy may be blown by the current, resulting in the above-mentioned failure.

In view of the drawbacks of the conventional products, the present invention provides a thermal fuse that operates safely when an overcurrent flows regardless of the ambient temperature.

In the thermal fuse according to the present invention, the temperature fusing part and the current fusing part are made of the same fusible alloy, and in the temperature fusing part, 7 lux is arranged around the fusible alloy, and in the current fusing part, the fusible alloy is An arc extinguishing agent is placed around the current fusing part, and the current capacity of the current fusing part is smaller than that of the temperature fusing part, and the two fusing parts are connected in series.

When such a thermal fuse of the present invention is thermally fused within the rated current, the fusible alloy in the thermally fused portion is fused by the action of flux.

Next, when an overcurrent flows, the fusible alloy pieces in the current fusing part having a small current capacity are fused.

At this time, the arc does not increase due to the action of the arc extinguisher, and safe fusing occurs.

Furthermore, even if an overcurrent flows when the ambient temperature is close to the melting point of the fusible alloy, since the fusible alloy in the temperature fusing part and the current fusing part are the same, the current with a small current capacity will always flow. Fuses at the fused part.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 denotes a eutectic fusible alloy (melting point: 143° C.) made of Sn-Pb-Cd, which has a cylindrical shape, and lead wires 4 are connected to both ends of the eutectic fusible alloy.

Reference numeral 2 is active resin-based flags, which is applied to the outer circumferential surface of the fusible alloy 1.

Reference numeral 3 is an arc extinguishing agent, which is made into a paste by mixing approximately 20 μm of silica sand and silicone grease, and is applied to the outer peripheral surface of the fusible alloy 1.

Reference numeral 5 is a flame-retardant epoxy paint that insulates the entire soluble portion including the lead wire 4.

Here, the part A is a temperature-fused part and is composed of a fusible alloy 1 and a flux 2.

On the other hand, part B is a current fusing part, and is composed of a fusible alloy having a smaller diameter than part A and arc extinguishing agent 3.

In a thermal fuse with such a configuration, a temperature rise occurs within the rated current, and when the temperature reaches the melting point of fusible alloy 1, 143°C,
The fusible alloy 1 is fused at the part where Clattus 2 is applied.

On the other hand, when an excessive current exceeding the rated current flows, the fusible alloy is fused at the current fusing portion B where the fusible alloy is thinned, and the action of the arc extinguisher 3 can prevent the arc from increasing.

Further, even if an excessive current flows at a temperature around 120 to 130° C., the same operation as in the above case is performed.

That is, the current fusion section B is fused.

As described above in the embodiments, the thermal fuse according to the present invention consists of a temperature fusing part and a current fusing part, both of which are made of the same fusible alloy, and the fusible alloy of the current fusing part is higher than that of the temperature fusing part. It is also designed to melt with a small current.

Furthermore, the temperature-fusing part is equipped with flux so that the fusible alloy melts quickly at abnormal temperatures, and the current-fusing part is equipped with an arc extinguisher to prevent damage from arcing when it melts due to excessive current. It is.

'Therefore, when a thermal fuse with the above structure is installed in a device, it will quickly melt when the device's temperature rises abnormally or if there is an excessive current, thereby preventing the device from emitting smoke or catching fire.

Note that even if the thermal fuse according to the present invention has a shape other than that shown in the examples, for example, the thermal fuse and the current fuser are made separately and connected later, or the thermal fuse is made of a fusible type in order to reduce the shape. The alloy may be formed into flakes, and a temperature fusing portion and a current fusing portion may be arranged on both sides of an insulating substrate.

Further, the current capacities of the temperature fusing section and the current fusing section are determined in consideration of the equipment used, the shape of the thermal fuse, the fusing temperature of the fusible alloy, and the like.

Furthermore, commonly used fluxes and arc quenching agents can be used.

Furthermore, the insulating film may be made of something other than epoxy paint, such as an inorganic or organic paint, a ceramic case, a resin case, or a metal case.

[Brief explanation of drawings]

The drawing is a diagram showing the configuration of a thermal fuse in an embodiment of the present invention. 1...fusible alloy, 2...flux,
3... arc extinguishing agent, 4... lead wire, 5...
...Insulating film.

Claims (1)

[Scope of Claims] 1. A temperature fusing part made of a fusible alloy and flux and a current fusing part made of the same alloy as the fusible alloy and an arc extinguisher are connected in series, and the current in the current fusing part is A thermal fuse whose capacity is smaller than that of the thermal fusion section. 2. The temperature according to claim 1, characterized in that the fusible alloy of the current fusing part is covered with an arc extinguisher on its outer periphery and has a smaller diameter than the diameter of the fusible alloy covered with flux. fuse.