JP2000356557A - Shape memory alloy heat sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate electronic equipment at a setting temperature without causing malfunction by combining a shape memory alloy and a normal spring and hence simplifying structure and miniaturizing a heat sensor. SOLUTION: The sensor is provided by combining a spring made of a shape memory alloy 2 and a normal reset spring 3, and a switch 4 is mounted to the end of a shaft 1. Then, the shape memory alloy 2 is pressed to the normal reset spring 3 and is held by a stopper that is fixed to the shaft 1. In this case, when a set operating temperature is reached, the shape memory alloy 2 reacts with it, exceeds the tension of the reset spring 3, operates on the stopper of the shaft 1, and operates the shaft 1. The released switch 4 is linked by the operation of the shaft 1, thus operating the switch 4 at a required temperature. In this manner, electrical equipment can be operated at a setting temperature with simple structure, the sensor can be utilized for detecting heat and for generating an alarm by mounting itself to the inside of a fire alarm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly used in a fire alarm for detecting heat and issuing an alarm.

[0002]

2. Description of the Related Art A conventional heat sensor for a fire alarm uses a diaphragm, bimetal, or the like.

[0003]

A problem to be solved by the present invention is to make a heat sensing sensor which is small and hard to cause a malfunction due to contamination or the like practical.

[0004]

Now, the solution will be described with reference to the drawings. A spring made of a shape memory alloy (2) and a reset spring are installed on a mandrel (1).

[0005] A switch (4) is attached to the end of the mandrel (1).

[0006]

According to the present invention, when the shape memory alloy (2) reaches the set temperature due to a change in heat, the tension of the reset spring (3) is exceeded and the mandrel (1) acts.

When the mandrel (1) operates, it activates the switch (4) fixed to the end, so that the switch (4) performs the set ON / OFF.

When the ambient temperature returns and the shape memory alloy (2) loses its acting force, the reset spring (3) acts and the mandrel (1)
To the initial state.

When the mandrel (1) is in the initial state, the switch (4) is released, loses its working force, and stops ON / OFF.

Embodiments will be described below.

Usually, the shape memory alloy (2) is stopped by a stopper fixed to the mandrel (1) and is held down by a reset spring (3).

When the operating temperature of the shape memory alloy (2) is reached,
The shape memory alloy (2) overcomes the tension of the reset spring (3) and causes the stopper of the mandrel (1) to act, thus actuating the mandrel (1).

When the mandrel (1) is operated, the switch (4) which has been released is operated in conjunction with the operation.

For this purpose, the switch (4) can be operated at a required temperature.

As described above, since the electronic device is operated at the set temperature with such a simple structure, an alarm or the like of a fire alarm can be activated.

[Brief description of the drawings]

FIG. 1 is a normal drawing of the present invention.

FIG. 2 is a drawing of the present invention in operation.

[Explanation of symbols]

 1 Mandrel 2 Shape memory alloy 3 Reset spring 4 Switch 5 Base

Claims (1)

[Claims] 1. A thermal sensor comprising a combination of a shape memory alloy and a normal spring.