JPS61148802A - Electric circuit - Google Patents

Abstract

PURPOSE:To change a circuit constant according to a change of temperature by using a shape memorizing alloy transformed into a coil shape in an electric circuit as a variable impedance element. CONSTITUTION:A shape of a coil of the illustration (b) is memorized at a high temperature by using a shape memorizing alloy (SMA) wire 1, and it is transformed into a linear shape of the illustration (a) at a low temperature. As a resonance circuit is formed by an inductance L of the SMA wire 1 and a capacitance C, whether it is over a predetermined temperature or not is detected by existance of a resonance state. For instance, when it is used as a fire alarm, it picks up a signal from the resonance circuit and reports, and it is also used as a temperature sensor without any contact. When it is used for gain adjustment of an amplifier, phase correction and a bridge circuit, it picks up the signal, and when it is used in a series with alternating current load and a temperature of the SMA wire is raised by excess current, a the current is automatically limited by a portion of the L, or the voltages at both ends of the portion of the L are detected to disconnect the circuit.

Description

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

[Conventional technology]

Recently, shape memory alloy (Shape Memory A1
1AY (hereinafter referred to as 8MA) is an alloy that has two functions: a temperature sensor and an actuator that operates by itself using the sensor, and its range of use is expanding. For example, 859.11.9 Asahi Shimbun (morning edition)
Various applications were introduced in "Science of Life", Mayu KM Agne "Metal J May 19B4 issue Vow 54. NO,
5'P2-8 is the practical application of Enercon's wind direction adjustment mechanism (
It is written about.

When ordinary metals are deformed beyond their elastic limit, they become plastically deformed and never return to their original shape.

However, even after applying 8 MAFi plastic strain, the shape is recovered. This is carried out by reversible martensitic transformation of deformation, which is memorized at high temperatures and deformed to a low mGc 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 parent phase, and it memorizes the high temperature and transforms into a dimensional shape.

This alloy has Ti-Ni type and Cu type, and Cu type includes Cu-Zn alloy, Cu-At alloy, Cu-Zn-At
Alloys etc. are used.

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

[Problem that the invention seeks to solve]

Conventional uses of SMA all involve the use of temperature sensors and their mechanical actions, and an example of a device being used as a single circuit element is a thermostat (which also uses mechanical actions). It is almost used for.

This invention uses 8MA as an electric circuit element.
'? The goal is to realize it (!).

[Means to resolve the issue once and for all]

The electric circuit of the present invention is constructed by using an SMA that deforms into a coil shape as a variable impedance element.

[Effect]

In the electric circuit of the present invention, when the deformation temperature becomes above or below a predetermined deformation temperature, the SMA changes into a coil shape, the inductance of the electric circuit changes, and the circuit constant of the electric circuit changes.

[Embodiments of the invention]

Hereinafter, a complete illustration of an embodiment of the present invention will be explained. 1st
In Figures (a) and (BL), 11 is a shape memory alloy (SMA) wire. When the ambient temperature or the temperature of the SMA wire tll reaches a predetermined deformation temperature or higher, it deforms to the original memory shape and becomes the shape shown in Figure 1 (bl). If used as an impedance element in an SMA'i electric circuit, it can be used as an impedance element in the circuit after reaching a predetermined deformation temperature.

An example thereof is shown in FIG. (2) is a capacitor (3
) are four sources of alternating current. At room temperature, the shape is as shown in FIG. 2(a), but when the temperature reaches a predetermined deformation temperature or higher, the shape becomes as shown in FIG. 2(b). At this time, if the inductance (L) of the coil of the SMA wire il+, the capacitance (C) of the capacitor, and the entire resonant circuit that resonates in series with the frequency of the AC source (3) are formed, the temperature will exceed the predetermined temperature. This can be known from the resonance state of M. Using this circuit, for example, it is possible to output a signal from the resonant circuit as a fire alarm to notify the fire alarm, and to generate radio waves from this circuit through an antenna, which can be used for alarms and monitoring. That is, it can be used as a non-contact temperature sensor.

In this example, the series resonant circuit can also be configured as a parallel resonant circuit, and it can also be used for amplifier gain adjustment, gain correction, phase correction, and one arm of the bridge circuit. 9. The signal 'kltX comes out. When an overcurrent flows in series with an AC load and the temperature of the SMA wire rises, the L component of the coil automatically limits the current and detects the full potential difference between both the L component and the L component. The detection signal can be used to disconnect the circuit. This can also be used to prevent overheating of IC circuits. This coil can be used as an AC or DC electromagnet, that is, by using the magnetic flux from the coil and detecting the magnetic flux, for various applications.

In this way, the effect of deforming the SMA wire into a coil shape can be widely used in electric circuits.

However, since these circuits can switch circuit constants without arranging contacts, there is a great advantage that leads to Nobukamo's note above.

FIG. 3 shows another embodiment of the invention.

(4) is a resistance, (la) and (lk+) are SMA wires that deform into coil shapes at different deformation temperatures, and (1b)
The force of (1a) makes the deformation temperature pi'i lower. (
5a) (51)) (5c) are terminals. Figure 3 (
a) is a case of low temperature, between terminals (5a) (5b) and (
5b) There is no signal between (5c). Next, the SMA wire (
When the y-shape of 1b) becomes m degrees or more, the state shown in FIG. 3('b) occurs, and a potential difference occurs between the terminals (5b) and (5c), and a signal appears. Furthermore, when the temperature exceeds the diamond shape of the SMA wire (1a), a signal also appears between the terminals (5a) and (5b).In this way, an electric circuit that detects multiple temperature change points is created. For example, a signal between terminals (5b) and (5c) generates an alarm, and a signal between terminals (5a and 5b) generates a treatment signal for an emergency situation. It may be inserted into multiple arms.

However, it can be widely applied to resonance circuits and other spiritual circuits.

In FIG. 3, two rows of SMA lines may be omitted, or three or more SMA balls may be used, each having a different degree of melody.

Well, in the Am example above, fih! In this case, it is possible to use an 8MA ball that deforms into a coil shape, but conversely becomes a coil shape at low temperatures and a 1α line shape at high knitting. Incidentally, the inductance of the coil changes even if the shape is changed from a coarsely wound coil shape to a densely wound coil shape without deforming it to a straight line shape, and therefore, it can be used in the same way.

〔Effect of the invention〕

As described above, according to the present invention, a shape memory alloy that deforms into a coil shape is used as a variable impedance element, and
Since it is used in @, it is possible to provide an entire electric circuit that changes the constant electric constant in response to a 1 m degree change.

[Brief explanation of the drawing]

Figure 1 (al '(b) is a principle diagram of a variable inductance element of this invention, and Figure 2 (a) (1)) is a principle diagram of a variable inductance element of this invention. (Is the air circuit diagram, Figure 3, another embodiment of this invention?
FIG. In the figure, ill (la) (1b) U shape memory alloy powder, (2) is a capacitor, and (3j is an AC flashlight. In the figure, the same reference numerals indicate 1- or equivalent parts.

Claims (3)

[Claims] (1) An electric circuit in which a shape memory alloy that deforms into a coil shape at a temperature above or below a predetermined temperature is used as a variable inductance element in the circuit. (2) The electric circuit according to claim 1, wherein when the variable inductance element is deformed into a coil shape, it forms a resonant circuit that resonates at a desired frequency. (3) Claim 1 characterized in that the plurality of variable inductance elements are each deformed into a coil shape at different predetermined temperatures to change the circuit constant thereof.
The electric circuit according to item 1 or 2.