JP4652547B2 - Actuator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shape memory material and an actuator using a superconducting phenomenon. The shape memory material of the present invention is applicable as a substitute for a movable aggregate such as an antenna in space and a powerful servo motor. The actuator of the present invention can be applied as a powerful aerospace actuator.
[0002]
[Prior art]
In general, shape memory materials change in shape according to temperature, and are applied to medical materials such as movable aggregates such as antennas in deep space, actuators of deep sea robots, and artificial valves.
[0003]
However, the shape memory material has a weak force, and it is difficult to apply it to a large-sized servo motor instead of a large servo motor. In addition, devices and systems such as large aircraft and spacecrafts that require advanced technology have major technical problems such as an increase in the number of parts, associated complexity, increased man-hours, and increased costs.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and includes a substrate and a thin film made of a shape memory material using a superconducting phenomenon formed on the substrate, and the shape memory material is in a magnetic field. Providing actuators that are likely to reduce the size of equipment and systems, reduce the number of parts, reduce man-hours, reduce costs, etc. by arranging materials that change shape with temperature. The purpose is to do.
[0006]
[Means for Solving the Problems]
The present invention comprises a substrate and a thin film made of a shape memory material using a superconducting phenomenon formed on the substrate, and the shape memory material is placed in a magnetic field and changes its shape depending on temperature. It is an actuator characterized by being.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
The features of the superconductivity-induced shape memory material are as follows.
1) In general, a shape memory material changes its shape by a unit stimulus such as temperature. In the present invention, a shape change is manifested by various stimuli such as temperature, magnetic field, current amount, light of a specific wavelength, and mechanical stress.
2) The shape memory effect is often exhibited at low temperatures. As a result, the force acting on the outside is often high output.
[0009]
In the present invention, examples of the superconducting material include metal Nb, YBa ₂ Cu ₃ O _7-x . In addition, it has been confirmed from experiments that A15 type compounds represented by NbTi alloy, Nb ₃ Sn, and V ₃ Si exhibit a shape memory effect. In addition, various superconductors including ceramics similarly include materials exhibiting a shape memory effect.
[0010]
In the present invention, the shape memory material changes its shape due to various environmental stimuli such as temperature, magnetic field, current value, specific wavelength light, and mechanical stress. Here, “various stimuli” means the above-mentioned temperature, magnetic field, current value, specific wavelength light, and mechanical stress.
[0011]
In the present invention, the actuator is configured by forming a thin film made of the shape memory material on the substrate. However, when forming a thin film on the substrate, for example, a magnetron sputtering apparatus as shown in FIG. 1 is used. . In FIG. 1, reference numeral 1 indicates a reaction vessel. In the reaction vessel 1, a target 2 is disposed at the upper portion, a holder 4 for supporting the substrate 3 is disposed at the lower portion, and a shutter 5 is disposed therebetween. Here, the shutter 5 is opened after being stabilized. A vacuum device (TP) 7a and a vacuum device (RP) 7b are connected to the lower and side portions of the reaction vessel 1 through valves 6a and 6b, respectively. Both vacuum devices 7a and 7b are also connected by a pipe 8 having a valve 6c interposed therebetween. The reaction vessel 1 is connected to a cylinder 9 containing H ₂ gas and a cylinder 10 containing Ar gas.
[0012]
【Example】
An embodiment of the present invention will be described below with reference to FIG.
FIG. 2 shows a cross-sectional view of a shape memory alloy actuator according to the present invention. In FIG. 2, reference numeral 21 indicates a substrate. On the Si substrate 21, a thin film 22 made of YBa ₂ Cu ₃ O _7-x or metal Nb is formed. The YBa ₂ Cu ₃ O _7-x , the metal Nb, the temperature, the magnetic field, the current value, the specific wavelength light, and the property that the shape changes due to various stimuli of the environment such as mechanical stress.
[0013]
Next, a method for manufacturing the actuator 23 having such a configuration will be described.
First, the Si substrate 21 is set on the holder 4 using the magnetron sputtering apparatus of FIG. Subsequently, after the inside of the reaction vessel 1 is evacuated using the vacuum devices 7a and 7b, the shutter 5 is opened, H ₂ gas and Ar gas are simultaneously sent into the reaction vessel 1, and a DC planar magnetron type sputtering gun is used. A thin film 22 having a thickness of about 2 μm was formed on the Si substrate 21. The film forming conditions were: ultimate vacuum: 3.9 × 10 ⁻⁵ Pa, leaked (gas leakage): 5.0 × 10 ⁻⁷ Pa · m ³ / s, Ar partial pressure: 6.0 × 10 ^{− 2} Pa, sputtering gas: Ar, target input power: 200 W, sputtering time: 3600 s, substrate material: Si (100) surface, substrate temperature: 300 K (room temperature).
[0014]
The shape memory alloy actuator according to the above embodiment is composed of a Si substrate 21 and a thin film 22 formed on the substrate 21 and made of YBa ₂ Cu ₃ O _7-x or metal Nb whose shape changes with temperature. Therefore, effects such as downsizing of devices and systems, a reduction in the number of parts, reduction of man-hours, and cost can be obtained.
[0015]
FIG. 3 shows a change in linear expansion using a uniaxial tensile linear dilatometer accompanying a change in temperature of a pure Nb superconducting material. In FIG. 3, Tc represents the superconducting transition temperature, and Load represents the tensile load. From FIG. 3, it was confirmed that when Nb wire was used as the superconducting material, softening / expansion phenomenon was observed just above the superconducting transition temperature.
[0016]
FIG. 4 is a diagram showing the relationship between temperature and excess strain in the superconducting material (YBa ₂ Cu ₃ O _7-x sintered material). In FIG. 4, the compressive stress is 4.6 MPa. From FIG. 4, it was confirmed that excessive strain was observed between 90K to 145K and 145K to 155K. In the case of the YBa ₂ Cu ₃ O _7-x sintered material, it was confirmed that the shape memory phenomenon was expressed like Nb.
[0017]
FIG. 5 is a diagram showing the relationship between temperature and strain in the superconducting material (YBa ₂ Cu ₃ O _7-x rapid solidification (QMG) material) in a magnetic field. From FIG. 5, when the temperature was raised to a superconducting transition temperature or lower in a magnetic field, a very large excess strain was found at the time of temperature rise. This is because the magnetic flux is pinned on the superconductor. That is, a sudden excess strain occurs due to repulsion between eddy current regions in the superconductor centered on the pinned magnetic flux. This means that a shape memory phenomenon with a large deformation amount and force is developed.
[0018]
A clear superconducting transition in the electrical resistance of this material is seen from 80K to 100K. 6A and 6B, the temperature dependence of the electrical resistance in this material has an inherent relationship similar to that of metal from room temperature to around 160 to 180 K (reference: Journal of Materials Science Letters, 8 (1989) pp. 700-702).
[0019]
When the temperature is 160 to 180 K or less, this relationship is deviated, and a superconducting transition phenomenon is started, and softening / expansion occurs. This volume change induces a shape memory phenomenon. Currently, softening is generally seen as a precursor of a superconducting transition, but it can be considered that it has already begun. Since the existing shape memory effect is mainly a martensitic transformation near room temperature, the volume change is not so large and a large stress cannot be expected. However, in the case of the YBa ₂ Cu ₃ O _7-x superconducting material shown in FIGS. 4 and 5, there is a large acting force due to the excessive strain observed in the low temperature region and the large atomic force (cohesive force) at the low temperature. It can be a shape memory material.
[0020]
In the above-described embodiment, the case where YBa ₂ Cu ₃ O _7-x and metal Nb are used is described. However, the present invention is not limited to this, and other superconductive materials may be used.
[0021]
In the above embodiment, the case where the superconducting material whose shape changes depending on the temperature and the magnetic field is described. However, the shape is not limited to this. To do.
[0022]
【The invention's effect】
As described above in detail, according to the present invention, a substrate and a thin film made of a shape memory material using a superconducting phenomenon formed on the substrate are provided, and the shape memory material is disposed in a magnetic field. with the structure that the shape by temperature is a material that changes Te, miniaturization of equipment and systems, such as large aircraft or spacecraft, a small amount of parts, man-hours decreased, likely attained cost reduction or the like actuator Can provide.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a magnetron sputtering apparatus according to the present invention.
FIG. 2 is a cross-sectional view of a shape memory alloy actuator according to an embodiment of the present invention.
FIG. 3 is a diagram showing a change in linear expansion using a uniaxial tensile linear dilatometer accompanying a change in temperature of a pure Nb superconductive material.
FIG. 4 is a graph showing the relationship between temperature and excess strain in a superconducting material (YBa ₂ Cu ₃ O _7-x sintered material).
FIG. 5 is a diagram showing the relationship between temperature and strain in a superconducting material (YBa ₂ Cu ₃ O _7-x rapid solidification (QMG) material) in a magnetic field.
FIG. 6 is a state diagram showing the relationship between electrical resistance and temperature in a YBa ₂ Cu ₃ O _7-x superconducting material.
[Explanation of symbols]
1 ... reaction vessel,
2 ... Target,
3 ... substrate,
4 ... Holder,
5 ... Shutter,
6a, 6b ... valves,
7a, 7b ... vacuum device,
8 ... Piping,
9, 10 ... cylinder,
21 ... Si substrate,
22 ... thin film,
23: Actuator.

Claims (2)

A substrate and a thin film made of a shape memory material using a superconducting phenomenon formed on the substrate, wherein the shape memory material is a material that is placed in a magnetic field and changes its shape depending on temperature. Characteristic actuator. The actuator according to claim 1, wherein the shape memory material is metal Nb or YBa ₂ Cu ₃ O _7-x .

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