JPH0224006B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an electric circuit using a shape memory alloy.

[Conventional technology]

Recently, shape memory alloy (Shape Memory Alloy)
SMA (hereinafter referred to as SMA) is an alloy that has the dual functions of a temperature sensor and acts as an actuator using the sensor, and its range of uses is expanding. For example, various applications were introduced in Asahi Shimbun (morning edition) ``Science of Life'' on Nov. 9, 1984, and KK Agne ``Metals'' May 1984 issue Vol.
No. 5, pages 2 to 8 describe practical application to air conditioner wind direction adjustment mechanisms.

When ordinary metals deform beyond their elastic limit,
It becomes plastically deformed and never returns to its original shape.
However, SMA recovers its shape even when subjected to plastic strain. This is done by reversible martensitic transformation, and the shape memorized at a high temperature is deformed by lowering the temperature below the temperature at which martensitic transformation occurs. Conversely, when the temperature is increased, a reverse transformation occurs from the martensitic phase to the original matrix phase, and the material deforms to the original shape memorized at the high temperature.

This alloy has Ti-Ni type and Cu type, and Cu type has
Cu-Zn alloy, Cu-Al alloy, Cu-Zn-Al alloy, etc. are used.

The temperature at which deformation occurs varies depending on the type of alloy, processing, heat treatment, etc., and various applications have been made to cause deformation at a predetermined temperature.

[Problem that the invention seeks to solve]

All conventional uses of SMA are based on temperature sensors and their mechanical action, and an example of their use as an element in an electrical circuit is in thermostats (which also use mechanical action). It was about warm.

An object of the present invention is to provide an element that uses SMA to form a mutual inductance circuit due to temperature changes.

[Means for solving problems]

The mutual inductance element of the present invention uses at least two SMA wires that can be deformed into a coil shape, and when deformed into a coil shape, forms a mutual inductance circuit.

[Effect]

When the deformation temperature exceeds or falls below the specified deformation temperature,
The SMAs transform into a coil shape and couple electromagnetically to each other.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In Figure 1 a and b, 1 and 2 are SMA lines,
10 and 20 are support points of the SMA wires 1 and 2. First, the coiled shape shown in FIG. 1b is memorized at a high temperature, and then deformed into the linear shape shown in FIG. 1a at a low temperature.
When the ambient temperature or the temperature of the SMA wires 1 and 2 exceeds a predetermined deformation temperature, the coil deforms to its original memorized shape and becomes the shape shown in FIG. 1b. In this way, the coiled SMA wires 1 and 2 can be electromagnetically coupled, and an electric circuit can be used as a mutual inductance element.

FIG. 2 shows an example of the circuit. In FIG. 2a, the circuit from the AC power source 4 through the resistor 5 does not transmit a signal to the circuit on the terminals 6a and 6b side. When the temperature exceeds the deformation temperature, the coiled SMA wires 1 and 2 are electromagnetically coupled, as shown in Figure 2b, and the terminal 6
The signal is transmitted to the a and 6b sides. There are various other circuits that use mutual inductance elements,
It can be used as a temperature sensor for fire alarms and temperature monitoring.

Figures 3a and 3b show another embodiment of the invention, 7
is an ordinary coil that is wound with copper wire, etc., and its shape does not change due to temperature changes. Then
Using SMA wire 2, arrange it corresponding to coil 7,
When the temperature rises, it deforms into a coil shape as shown in FIG. 3b and is electromagnetically coupled to the coil 7. In this way, a circuit may be formed using only one of the two coils using an SMA wire.

In addition, in the example shown in Fig. 4, when an overcurrent flows through the load 9, the state changes from the state shown in Fig. 4 a to the state shown in Fig. 4 b.
The SMA wire 1 is deformed into a coil shape and gives a signal to the coil 7, and this signal can be used to issue an alarm or cut off the load.

In Figures 5a and 5b, the two SMA wires 1 and 2 are coiled and transmit two signals to terminals 6a, 6b and 8.
This is an example of a circuit taken out from a and 8b, in this case,
By setting the deformation temperatures of SMA wires 1 and 2 to be different, signals can be detected at different temperatures. In this way, various circuits can be constructed using a plurality of coils.

In the above embodiment, the wire is deformed into a coil shape at high temperatures, but an SMA wire that deforms into a coil shape at low temperatures and into a straight line at high temperatures may also be used. Further, although the deformation has been described in terms of two shapes, a coil shape and a linear shape, the coil may change into two shapes: a case where the coil is tightly wound and a case where the coil is loosely wound.

〔Effect of the invention〕

As described above, according to the present invention, since a shape memory alloy that deforms into a coil shape is used as a mutual inductance element, a mutual inductance circuit that responds to temperature changes can be formed.

[Brief explanation of drawings]

FIGS. 1a and 1b are principle diagrams of a mutual inductance element according to an embodiment of the present invention, FIGS. 2a and 2b are electrical circuit diagrams using a mutual inductance element according to an embodiment of this invention, and FIGS. 4 and 5 are electrical circuit diagrams showing other embodiments of the invention, respectively. In the figure, 1 and 2 are shape memory alloy wires, 3 is a shape changing section, 4 is an AC power source, 5 is a resistor, and 7 is a coil. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A mutual inductance element having at least two shape memory alloys that deform into a coil shape at a temperature above or below a predetermined temperature, and arranged so as to be electromagnetically coupled to each other when the shape memory alloys are deformed into a coil shape. 2. The mutual inductance element according to claim 1, which uses a shape memory alloy that deforms into coil shapes at different deformation temperatures. 3. Coiled deformation refers to changing the degree of electromagnetic coupling by deforming from a sparsely wound coil shape to a densely wound coil shape, or from a densely wound coil shape to a sparsely wound coil shape. A mutual inductance element according to claim 1 or 2. 4 It has a deformable coil made of a shape memory alloy that deforms into a coil shape at a temperature above or below a predetermined temperature, and another non-deformable coil, and when the deformable coil deforms into a coil shape, it electromagnetically interacts with the non-deformable coil. Mutual inductance elements arranged to couple.