JPH04473Y2 - - Google Patents

Description

[Detailed description of the invention] This invention fixes one end of a rectangular plate-shaped body of a shape memory alloy to the inner wall surface of a non-magnetic duct partition, which is plastically deformed by applying a deforming force and returns to its pre-deformed shape by heating. This is a temperature sensor in which a rod-shaped permanent magnet is fixed to the other end, and a reed switch is attached to the outer wall of the bulkhead at a position corresponding to the position of the permanent magnet so that the direction of the magnetic pole matches the direction of the reed contact piece. .

Conventionally, in temperature sensors for fire alarms, an electric current is constantly passed through a fusible metal that melts at a specified temperature, and when the temperature rises due to a fire, etc., the alloy melts and the electric current is cut off, causing an alarm. Something that emitted was used. However, this type of sensor is designed so that the current is cut off in the event of a disaster, so even if the alarm circuit is disconnected or the wiring between the sensor and the alarm is disconnected, the alarm will be activated and the alarm will not be detected. It was mistakenly recognized as something detected by a device. In addition, easy-to-fuse metals are melted and cannot be used again.
Since it is not reusable, it has the disadvantage that individual operations cannot be inspected.

The present invention eliminates such drawbacks of the conventional method and uses a permanent magnet fixed to a shape memory alloy whose shape returns to its original shape before plastic deformation when heated after being plastically deformed, and a reed switch in close proximity to the reed switch. It is a temperature sensor that can be opened or closed, and is reusable and allows individual characteristic testing.

Next, an embodiment of the present invention is shown in FIG. It consists of a plate-like body 1 made of a shape memory alloy with a permanent magnet 2 fixed to its tip, and a reed switch 5 provided at a position facing the magnet.

Shape memory alloys are made of nickel-titanium alloys, nickel-aluminum alloys, copper-based alloys, etc., and have a shape-memory effect in which the shape returns to the plastically deformed state when it is heated after being plastically deformed by applying a deforming force. When these alloys are heated, they are deformed by causing reverse transformation to an austenite phase at a temperature that is a reverse transformation point. Furthermore, the temperature is 20℃ higher than the reverse transformation point.
When the temperature reaches ~50℃ lower, martensitic transformation occurs from austenite phase to artensite phase,
It returns to its original form again.

As shown in Fig. 1, the present invention uses a shape memory alloy as a rectangular plate, and attaches one end of the shape memory alloy to the inner wall surface of a non-magnetic partition wall 3' of a duct 3 through which ventilation, smoke exhaust, piping, wiring, etc. are passed. It is fixed via a spacer 4. Also, at the other end of the plate-like body 1, there is a partition wall 3' of the duct.
A permanent magnet 2 is fixed on the opposite surface so that the direction of the magnetic pole is parallel to the longitudinal direction of the plate-like body 1. The outer wall surface of the partition wall 3' of the duct 3 is leaded so that when the permanent magnet 2 approaches the partition wall 3', the internal contact pieces 6 and 6' match the direction of the magnetic poles at a position facing the permanent magnet 2. Fix switch 5.

Now, under normal conditions, the plate-like body 1 is plastically deformed into an arcuate shape by setting the weight of the permanent magnet 2 to be larger than the yield force of the plate-like body 1, and the permanent magnet 2 is separated from the reed switch 5. It is assumed that the contact pieces 6, 6' are separated.

If a fire breaks out in the room, the temperature rises abnormally, and the shape memory alloy reaches its reverse transformation temperature.
The plate-like body 1 reversely transforms from the martensite phase to the austenite phase and returns to the flat state before plastic deformation. Therefore, as shown in FIG.
is close to the reed switch 5, and its contact pieces 6, 6'
close. When the leads 7 and 7' connected to the outside of this reed switch 5 are connected to the alarm circuit,
When a fire breaks out indoors, it can be notified.

When the fire is extinguished and the temperature inside the duct 3 decreases and reaches the transformation point, the plate-shaped body 1 undergoes martensitic transformation from the austenite phase to the artensite phase, becomes arched again as shown in Fig. 1, and becomes permanent. The magnet 2 is separated from the reed switch 5 and its contact pieces 6, 6' are separated.

The shape memory alloy forming this plate-like body 1, for example, in the case of a nickel-titanium alloy, undergoes repeated transformation between an austenite phase and a martensitic phase unless oxidation progresses by exposing it to a high temperature state of 500°C or higher for a long time. I can give it back.

In the drawings for the above explanation, FIG. 1 shows the plate-shaped body 1 fixed in parallel to the cross-sectional direction of the isolation 3'.
In FIG. 2, the partition wall 3' of the duct is fixed parallel to the longitudinal cross-sectional direction. FIG. 3 shows another embodiment of the present invention, in which the plate-shaped body 1 is not attached through the spacer 4 as shown in FIG. 1, but is attached to a part of the partition wall 3'. When the spacer 4 is unnecessary and the partition wall 3' is made of non-magnetic metal,
Since heat conduction is also good, there is an advantage that heat can be quickly and reliably transmitted to the plate-shaped body 1.

As described above, the present invention can quickly detect abnormal temperatures and issue an alarm when a fire occurs. Furthermore, since the sensor is capable of self-recovery, it has the advantage of being able to be tested individually as a single component. The sensor of the present invention can be used not only for detecting fire, but also as a sensor for detecting temperature in liquid tanks and air tanks.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional perspective view of an embodiment of the sensor of the present invention fixed parallel to the cross-sectional direction of the partition; Fig. 2 is a cross-sectional perspective view of the sensor of the present invention fixed parallel to the longitudinal cross-section of the partition; FIG. 3 is a sectional view of another embodiment in which the sensor of the present invention is directly inserted into the partition wall. The symbols in the drawings are 1... plate-shaped body, 2... permanent magnet, 3... duct, 3'... partition wall, 5... reed switch, 6, 6'... contact piece.

Claims (1)

[Scope of utility model registration request] In a temperature sensor for a duct fire alarm, one end of a rectangular plate-like shape memory alloy that has been plastically deformed by applying a deforming force is fixed to the inner wall surface of the duct partition, and a rod-shaped permanent magnet is fixed to the other end. A temperature sensor for fire alarm, comprising a reed switch that faces the permanent magnet and has a magnetic pole aligned with and close to the direction of the contact piece, and is attached to the outer wall surface of the duct partition.