JP2001165036A - Shape memory alloy coil actuator and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SMA coil actuator given a coil spring for a bias capable of responding to even diametrically thinning though having a displacement amount and generating force exceeding a general coil spring and an oscillating structural body capable of effectively displaying a characteristic of this actuator. SOLUTION: An actuator of competitive type structure is constituted by connecting an SMA coil spring 1 and a coil spring 2 for a bias so as to compete with each other, the SMA coil spring of super elasticity, formed so as to indicate reset force by super elasticity at a peripheral temperature at use time of this actuator, is used as the coil spring 2 for a bias. An oscillating structural body is formed by providing this actuator in a long-scaled object having a part which must be flexed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an actuator using a shape memory alloy (hereinafter also referred to as "SMA") coil spring.

[0002]

2. Description of the Related Art An SMA coil actuator is an SMA coil actuator.
The operation in which the coil spring is deformed (recovered) into a memory shape is used as a driving source. Hereinafter, a shape obtained by deforming the “memory shape” stored in the SMA coil spring to a state in which the SMA coil spring can operate as an actuator will be referred to as an “initial shape”.

[0003] The structure of the SMA coil actuator is mainly an antagonistic structure in which an SMA coil spring as a driving source and a bias coil spring for opposing the SMA coil spring are combined so as to antagonize each other like an antagonistic muscle. The reason for adopting the antagonistic structure is that the SMA coil spring generally cannot return from the memorized shape to the initial shape again by itself. By reversing the bias coil spring so that the SMA coil spring that has recovered to the memorized shape returns to the initial shape when not heated, repetitive reciprocating operation as an actuator becomes possible.

As a bias coil spring in the conventional antagonistic structure, a coil spring made of SUS or general spring steel (hereinafter, "general coil spring") is used, and a normal SMA coil spring (the same as the driving side) is used. )).

[0005]

However, the coil specifications (element wire diameter, coil outer diameter, etc.) of the bias coil spring may be almost the same size as the SMA coil spring on the drive side due to space limitations. Many. Under such conditions, when a general coil spring is used for bias, there is a problem that the general coil spring has a small elastic range, and thus the amount of operation displacement is small.

In the latter case, in which the SMA coil spring is used for biasing, the displacement and the generated force are more advantageous than the former. However, in order to operate the SMA coil spring, it is necessary to heat the coil using a means such as energization. Therefore, not only for driving but also for bias, a connection portion with an energizing lead wire, a space for wiring, etc. Is required. Generally, it is difficult to join the SMA to another metal, and it is not preferable in terms of manufacturing to increase the number of connection parts. Further, an increase in the space for wiring is disadvantageous in applications requiring a small diameter, such as a swing structure of the endoscope distal end portion.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a shape memory alloy coil actuator provided with a bias coil spring capable of responding to a reduction in diameter while having a displacement and a generation force larger than those of a general coil spring. It is another object of the present invention to provide a swing structure that is an application that can effectively exhibit the features of the shape memory alloy coil actuator.

[0008]

SUMMARY OF THE INVENTION The present invention has the following features. (1) An actuator having an antagonistic structure in which a shape memory alloy coil spring and a bias coil spring are connected so as to oppose each other, and are configured to output a reciprocating operation in accordance with heating / non-heating of the shape memory alloy coil spring. Wherein the bias coil spring is a superelastic shape memory alloy coil spring formed so as to exhibit a restoring force due to superelasticity at an ambient temperature during use of the actuator.

(2) The shape memory alloy coil actuator according to the above (1) is provided on a long object having a portion to be bent, and the shape memory alloy coil actuator is configured to directly or via a traction wire to bend the shape memory alloy coil actuator. A swing structure which is attached to a long object so as to connect both ends of a portion to be bent, and wherein a portion to be bent according to a reciprocating operation of the actuator performs a swing operation.

(3) A plurality of the shape memory alloy coil actuators are provided in parallel so that a part to be bent is swung in different directions.
A swing structure as described.

(4) The shape memory alloy coil actuator has a configuration in which a shape memory alloy coil spring and a bias coil spring are connected in series, and when the shape memory alloy coil spring contracts, it is pulled by it. The swing structure according to the above (2), wherein the bias coil spring extends.

(5) The bias coil spring of the shape memory alloy coil actuator is attached to the elongated object such that the bias coil spring is located on the side opposite to the shape memory alloy coil spring of the actuator with respect to the longitudinal axis of the elongated object. The shape memory alloy coil spring and the bias coil spring are connected in parallel via a long object, and when the shape memory alloy coil spring contracts, the bias coil spring is extended by being pulled by the bent long object. The above configuration (2)
A swing structure as described.

(6) The shape memory alloy coil spring of the shape memory alloy coil actuator is heated and contracted, and one end of the coil spring is connected to one end of the portion to be bent, and the portion to be bent. And the other end of the coil spring are connected via a pulling wire, and the biasing coil spring of the actuator is a compression spring and is elongated along the portion to be compressed by bending of the portion to be bent. The swing structure according to the above (2), which is attached to a shaku.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An SMA coil actuator according to the present invention (hereinafter, also simply referred to as "actuator").
As shown in FIG. 1, a SMA coil spring 1 and a bias coil spring 2 are connected so as to oppose each other and are attached to a support a. The SMA coil spring 1 is a driving source, and recovers to a memory shape by heating. The biasing coil spring 2 is a superelastic SMA coil spring, and is formed so as to exert a biasing force by superelasticity at an ambient temperature during use.

With the above configuration, the bias coil spring is restored to the memory shape by superelasticity when the load is removed without heating. Therefore, the return force shown when the bias coil spring 2 is displaced by the SMA coil spring 1 is mainly a force due to superelasticity, and the normal S
Large displacement and generated force equivalent to the case where the MA coil spring is used for bias can be obtained. In addition, as in the case where a general coil spring is used for bias, a compact design that does not require any additional components or connection parts for heating becomes possible.

The operation itself as an antagonistic structure or an actuator may refer to a known one. Hereinafter, each part will be described with reference to some examples of the antagonistic structure.

FIG. 1A shows an example of an antagonistic structure in which an SMA coil spring 1 and a bias coil spring 2 are pulled in series with each other. In the example shown in the figure, the recovery of the SMA coil spring 1 to the stored shape is contraction. First, from the state of the initial shape where both are balanced, the SMA coil spring 1
Is heated and contracted, the bias coil spring 2 is expanded and stores a restoring force. Next, SMA coil spring 1
When the temperature of the coil spring 1 is lowered, the coil spring 1 is again deformed to the initial shape by the coil spring for bias, and
Complete the cycle. At this time, the force reciprocating in the direction of the arrow can be taken out, for example, from the connection portion m. An SMA coil spring 1 of a type whose recovery to the memory shape is elongated may be used, and an antagonistic structure in which the coil springs 1 and 2 press in series with each other may be used.

In the example of FIG. 1B, the SMA coil spring 1
And the biasing coil spring 2 are connected in parallel via a connection portion m, and the SMA coil spring 1 has a parallel antagonistic structure in which the biasing coil spring 2 contracts. As in the case of FIG. 1A, the SMA coil spring 1 may be of a type in which the operation of recovering the memory shape is extension.

In the example of FIG. 3A, the SMA coil spring 1
And the biasing coil spring 2 are attached to the bendable support member A so as to be located on opposite sides (front and back) with respect to the longitudinal axis. In this example, the support A also serves as a connection portion between the two coil springs.
The two coil springs 1 and 2 oppose each other in parallel on the front and back sides of the support A. When the SMA coil spring 1 contracts, the support A bends in the direction of the arrow, and the bias coil spring 2 is extended by being pulled by the bending. Stores resilience. This example uses SMA
Although it is a coil actuator, it is itself a single swing structure.

The ambient temperature at the time of use of the actuator is not limited as long as it is a general temperature such as air temperature, room temperature, body temperature and the like in terms of application. For example, if used as a general manipulator, temperature and room temperature are important,
The standard is about 0 ° C to 50 ° C, and 25 ° C to 38 ° C for normal controlled use at room temperature or application to living organisms.
It is about. Conversely, the ambient temperature when the actuator is used is changed to the temperature (transformation temperature) at which the shape memory effect of the SMA coil spring on the drive side is manifested, or to the A _f point of the superelastic material (the martensite reverse transformation occurs when heated). (Temperature to complete). The ambient temperature during use is S
If it is lower than the transformation temperature of the MA coil spring, the actuator operates theoretically. The ambient temperature during use may be any temperature as long as it is equal to or higher than the _Af point of the bias coil spring. If no stress is applied to the actuator, the ambient temperature during use may be slightly higher than the point _Af . However, some stress is usually applied to the actuator,
The greater the stress, the greater the difference between the ambient temperature and the point from the A _f point. From these points, an appropriate ambient temperature is generally in the range of (A _f point + 10 ° C.) to (A _f point + 50 ° C.).

The bias coil spring used in the present invention is a superelastic SMA coil spring formed of SMA exhibiting superelasticity as described above, and uses SMA exhibiting superelasticity (such as a Ni-Ti alloy described later). This is a coil spring formed to recover to its original shape by superelasticity from deformation due to compression and tension applied at the temperature during use. Superelasticity (pseudoelasticity) is one of the phenomena exhibited by SMA. When the SMA is deformed at a temperature higher than the point A _f , an external force is applied even when a strain of several percent, and in some cases, 20% is generated. When removed, it is a phenomenon in which it apparently recovers to its original shape like elastic deformation. In the present invention, the super elasticity of SMA is
This is applied to the return force of the bias coil spring of the SMA coil actuator.

The material for making the bias coil spring a superelastic SMA coil spring may be any superelastic SMA material that exhibits superelasticity at least at the ambient temperature during use. Among them, Ni-Ti alloy is a preferable material which exhibits particularly remarkable superelasticity at the operating temperature of the actuator of the present invention. Other examples include copper-based alloys such as Cu-Al-Ni alloys.

The superelasticity of the Ni-Ti alloy includes superelasticity due to martensitic transformation and superelasticity due to work hardening, and the former mode of utilizing superelasticity is preferred. Ni-
In the case of a Ti alloy, the energy density that can be stored and the energy storage efficiency can be changed by appropriately selecting the composition, processing, and heat treatment of the alloy. For example, Ti-50.
The 6 at% Ni alloy is not preferable in terms of superelasticity when it is a solution-treated material from 1273 K, but when it is aged at 673 K for 1 hour, good superelasticity can be obtained. For an alloy having a Ni concentration of 50.5 at% or less without age hardening, preferable superelasticity can be obtained by annealing at 673 K without solution treatment after cold working.

The A _f point of the Ni—Ti alloy varies depending on the composition ratio and heat treatment (solution treatment, aging, annealing, etc.), but is in the range of about −50 ° C. to about 70 ° C. And
The behavior that can be regarded as superelasticity is from _Af point to ( _Af point + 100
° C), and a particularly preferable superelastic behavior is about ( _Af point + 10 ° C) to ( _Af point + 50 ° C), depending on the stress applied to the actuator. is there. For example, some Ti-49.2 at% Ni alloys have an A _f point of 5 ° C., so that a preferable superelastic behavior can appear in a range of about 25 ° C. Compatible with ambient temperature.

Using the above superelastic SMA material, superelastic SM
The method of manufacturing the A coil spring is roughly as follows: a superelastic SMA material suitable for the ambient temperature at the time of use is processed as a wire, the wire is used as a wire to form a coil spring, and a necessary heat treatment is performed. A coil spring capable of generating a returning force mainly composed of superelasticity at ambient temperature. As an example, a superelastic SMA material Ti-49.2 at% Ni
By winding a wire (alloy diameter 0.2 mm) made of an alloy into a coil shape (coil specification is arbitrary), and heat-treating this at 500 ° C. for 1 hour, the A _f point is about 5 ° C.
A bias coil spring that generates a preferable return force mainly composed of a superelastic material is obtained.

The coil specifications of the SMA coil spring and the bias coil spring constituting the actuator may be freely determined. For example, the coil shape may be a simple cylindrical shape, a conical shape, or the like, and the pitch may be constant or variable. The processing and processing of both ends of the coil may be in the form of the end of a coil spring used in a conventional antagonistic SMA coil actuator, such as processing for flattening the end face and processing for forming a hook-shaped hook.

Although there is no limitation on the use or scale of the actuator, the feature of using a biasing coil spring having a large generating force and capable of reducing the diameter is most remarkable in medical instruments for insertion into the body and micro-power. This is a case where the present invention is used for a long micromachine such as a manipulator, which requires a finer outer diameter. In particular, the tip end swing mechanism of an endoscope or the like (mechanism capable of repeating reciprocating bending operations)
And an active bending mechanism of a catheter (a mechanism that can be bent according to the internal shape of the insertion object so that it can be smoothly inserted into a bent blood vessel, etc., and is the same as a swing mechanism) Actuators for forming are preferred applications.

The outer diameter of each coil of the SMA coil spring and the bias coil spring may be an ultra-fine value that can be used for such a long micromachine as described above. Specifically, a preferable value is 1 mm or less, which is a unique range required for the coil outer diameter in the field of micromachines. For example, in the application to a catheter, the specific coil outer diameter of the SMA coil spring and the bias coil spring is 0.15 mm to 0.6 mm.
It is about. Further, the lower limit of the coil outer diameter is not limited, and may be reduced without limit in accordance with the improvement of the processing technique of the single filamentary wire, the processing technique of the bundled wire, the processing technique of the coil winding, etc. It is about 075 mm.

A known shape memory alloy may be used for the SMA coil spring on the drive side. For example, Ti
-Ni-based alloy, Ti-Ni-Cu-based alloy, Ti-Ni-
Fe-based alloy, Ni-Al-based alloy, Ag-Cd-based alloy, A
u-Cd alloy, Cu-Al-Ni alloy, Cu-Au
-Zn alloy, Cu-Sn alloy, Cu-Zn alloy,
Cu-Zn-Al alloy, In-Ti alloy, In-C
d-based alloys and the like.

In order to operate the actuator by remote control, the SMA coil spring on the driving side may exhibit a shape-memory effect by various heating methods. Examples of the heating method include a method of irradiating a laser beam through an optical fiber and a method of energizing an SMA coil spring.

Next, the swing structure of the present invention will be described.
The swing structure includes a swing mechanism (active bending) configured to attach the actuator to a long object and freely swing the long object by an external heating operation on the SMA coil spring of the actuator. Mechanism).

The swing operation is an operation of displacing or twisting and returning at least to the original position. If the head swing is only required to be displaced in one direction and returned to the original state from a certain state, one actuator for displacing and a bias force for returning to the original state are required. The bias force may be a bias force due to the elasticity of the bending object itself such as a long object, or a spring may be used. However, in the following example, the long object can be bent at least in the opposite directions with respect to the state where the long object is linear (that is, there are three or more stable positions including the center position). As described above, an embodiment in which a plurality of actuators are provided will be described.

The long object may have any part to be bent. The portion to be bent only has to be bendable, and the entire section may be flexible or elastic, or may be one where a rigid body bends like a universal joint. The long object is an object that can be freely bent by the actuator, and is also a support body described in the description of the actuator. Examples of the long object include a catheter, a medical device for insertion into a living body such as an endoscope, a central body portion such as a micromanipulator, and a tube through which these are inserted, as described above as applications of the actuator.

In the following example, a long object will be described as a small-diameter flexible tube used for an endoscope or the like.
The portion of the tube that should be bent (hereinafter referred to as the “swinging portion”) is a portion that bends by receiving a pulling force or an extension force from the actuator. Thus, the bent portion can be freely set.

In the example shown in FIG. 2A, two actuators are mounted on the front and back of the flexible tube, and can swing in the direction of the arrow. The number of actuators is preferably three as described later, but is two for the sake of explanation (the same applies to other examples below). In the example shown in the figure, an actuator (100, 101) is attached to one end of the swinging part, and the other end of the swinging part is pulled by the pulling wires (3, 13). In the example of the figure, the actuator section is between A1 and A2,
The part between A2 and A3 is the swing part. The antagonistic structure (antagonism between the SMA coil spring 1 and the biasing coil spring 2 and also between 11 and 12) in each actuator is as follows.
This is the same as the example of FIG. By controlling each actuator and pulling the pulling wire, it is possible to perform a swing motion in which the actuator is bent from the center position to both sides.

Although the pulling wire is used in the example shown in FIG. 2A, the other end of the swinging portion may be directly pulled by the biasing coil springs 2 and 12 as another mode. That is, SM is attached to the side A1 at one end of the swing part.
One end of the A coil spring is connected, one end of the bias coil spring is connected to the other end of the SMA coil spring, and the other end of the bias coil spring is connected to the other end A3 of the swing part.

Although the number of actuators in the example shown in FIG. 2A is two, three or more actuators are required to make the flexible tube freely bendable in any direction. As shown in the cross section in (b), a mode in which three are provided in parallel at equal intervals around the body of the flexible tube (that is, a mode in which the flexible tubes are arranged every 120 °) is preferable because the objective can be achieved with a minimum number. . The combination of the forces generated by the actuators (100, 101, 102) enables bending in an arbitrary direction. Hereinafter, the same applies to other embodiments.

In the example of FIG. 3A, as described in the description of the actuator, the SMA coil spring 1 and the bias coil spring 2 are set on the front and back with the flexible tube A interposed therebetween to form a swinging structure. This configuration,
In comparison with a mode in which the actuator section and the swinging section are separately provided in series in the longitudinal direction of the long object, the actuator section and the oscillating section are compact.
The A coil spring and the bias coil spring are arranged in parallel to be compact. Accordingly, the actuator portion is completely overlapped with the swing portion, and the bending operation can be freely performed only in the section required for the swing portion.

Also in this example, in order to enable free bending in any direction, three sets of actuators are provided at equal intervals around the body of the flexible tube as shown in FIG. 3B. preferable. The set of SMA coil spring and bias coil spring of each actuator is:
1 and 2, 11 and 12, 21 and 22. Three SMAs
Paying attention to the coil springs 1, 11, and 21, they are arranged at every 120 ° around the body of the flexible tube, as in FIG. 2B.

In the example of FIG. 4, the swing portion is a section between A2 and A3. As in the examples of FIGS.
Although one is provided, one of the actuators will be described as a representative. Actuator 100 in the embodiment shown in FIG.
The SMA coil spring 1 is of a type that recovers in the direction of being heated and contracted, and one end thereof is connected to a predetermined portion A1 on one end side of the swing part. In the example shown in the figure, A1 is a position separated from one end A2 of the swing part by the length of the SMA coil spring. And the coil spring 1
And the other end A3 of the part to be bent,
It is connected via a traction wire 4.

On the other hand, a compression spring is used as the bias coil spring 2. Both biasing coil springs 2 are attached to a long object along the oscillating portion so as to be compressed when the oscillating portion is bent. For example, in the embodiment shown in FIG. 4, compression spring setting support portions A20 and A30 are provided to protrude at both ends A2 and A3 of the swinging portion, respectively, and a bias coil spring is set therebetween. The pulling wire 4 passes through the hole of the support portion A20, passes through the inside of the bias coil spring, and passes through the support portion A3.
Connected to 0. In this configuration, when the SMA coil spring 1 of the actuator is contracted, the swinging portion bends toward the actuator 100 by pulling through the pulling wire. At this time, the biasing coil spring 2 is compressed by the support portions A20 and A30. It can store the restoring force.

As described above, when the swing structure is formed by using the actuator of the present invention, since the superelastic SMA coil used for the bias coil spring has already completed the transformation when operating, the transformation is completed. It is in a stiffer spring state than when it is not. Therefore, as shown in FIG. 4, in a mode in which the bias coil spring is arranged along the oscillating portion, it is possible to impart to the oscillating portion a strength that does not cause buckling even when it is opposed to the SM coil spring.

Further, since the superelastic SMA coil can take a larger distortion than a general coil spring, it is possible to increase the stroke at the same size. In other words, when the same stroke is taken, the set length can be shorter than that of a general coil spring, and the length of the swing part and the length of the swing structure can be shortened accordingly.

Also, as described in the description of the actuator, by using the superelastic SMA coil as the bias coil spring, a compact design that does not require any additional parts for heating or connection parts can be made, similarly to a general coil spring. Becomes

In the embodiments illustrated in FIGS. 2 to 4, only the mounting relationship between the long object and the actuator is shown. However, in an actual swing structure, the connection of each part between the long object and the actuator is shown. For this purpose, as shown in FIG. 5, various structures are provided, such as providing connection ring-shaped portions (which may be integral with the long object or may be separate parts) A10, A20, and A30 that protrude from the long object. May be.

When a plurality of actuators are mounted around the body of a long object, as shown in FIG. 5, the node rings R1 and R1 can maintain the positional relationship of each coil spring in the direction around the body.
R2 and R3 may be used so that the coil springs do not shift in the direction around the body of the long object.
The node ring is a member provided for each fixed section in the longitudinal direction of the long object, and may be an integral part of the long object or a separate part. The node ring has a hole for inserting a long object at the center thereof and a hole for inserting a coil spring around the hole. In the example of FIG. 5, the bias coil spring is inserted into a hole around the node ring, and is fixed so as not to be displaced in the direction around the body of the long object. In addition, the swing structure may be provided with a jacket tube that covers the entire mechanism.

[0047]

EXAMPLES The present invention will be specifically described below with reference to examples. In the present embodiment, the swing structure of the mode described in FIG. 4 was actually manufactured. The specific appearances of the coil spring and the node ring are as illustrated in FIG. 5, but the outer diameter of the long object does not change such that the bent portion becomes thin. 3 actuators
And is attached to a long object in the positional relationship shown in FIG. The specifications of each part are as follows.

Elongate object: The outer diameter of the central body of the fiberscope as an endoscope, where the SMA coil spring 10 is set, is 2.8 mm, and the swinging part A2
The outer diameter of A3 is 2.8 mm. SMA coil spring: material Ni-Ti alloy, strand diameter 0.1
mm and a coil outer diameter of 0.3 mm were bundled to form a set of actuator driving coils, and three sets of these were mounted around a long object. Initial shape length (set length)
46mm, length 39mm in memory shape. Coil spring for bias: Material Ni-Ti alloy, wire diameter 0.2 mm, coil outer diameter 0.75 mm, natural length 32 m
m, set length 29.5 mm. The outer diameter (circumscribed circle diameter) of the portion to which the bias coil spring is attached is 2.8 mm, and the entire length A1 to A of the portion that has become the oscillating structure in the longitudinal direction of the fiberscope.
3 was 78 mm.

Each SMA coil spring is individually and arbitrarily combined and energized, and each coil spring is contracted by exhibiting a shape memory effect. I found it.

Comparative Example In this comparative example, a swing structure having bending performance equivalent to that of the above-described embodiment was manufactured using a general coil spring as a bias coil spring, and the shapes such as the outer diameter and the overall length were compared. A swing structure was manufactured in the same manner as in Example 1 except that a general coil spring was used as the bias coil spring, and the dimensions required for the coil spring were changed. The specifications of a bias coil spring using a general coil spring are as follows: a wire diameter of 0.2 mm, a coil outer diameter of 0.9 mm, a natural length of 60 mm, and a set length of 57.5 mm. The outer diameter (circumscribed circle diameter) of the portion to which the bias coil spring was attached was 3.1 mm, and the total length of the portion that became the swing structure was 106 mm.

By comparison between this embodiment and the comparative example, when a swing structure having the same performance is formed, the actuator according to the present invention is thinner and shorter than one using a general coil spring for bias. It became clear what we could do.

[0052]

As described above, in the actuator of the present invention and the swing structure using the same, the super-elastic SMA coil spring is used as the bias coil spring, and the displacement is larger than that in the case of using the same size general coil spring. Has quantity and power. Moreover, as compared with the case where the SMA coil spring is used as the bias coil spring, the diameter can be reduced by the absence of the heating structure.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration example of an actuator of the present invention.

FIG. 2 is a schematic diagram showing a configuration example of a swing structure of the present invention.

FIG. 3 is a schematic view showing another configuration example of the swing structure of the present invention.

FIG. 4 is a schematic view showing another configuration example of the swinging structure of the present invention.

5 is a diagram more specifically showing the configuration of each part of the swinging structure shown in FIG. 4;

[Explanation of symbols]

 A long object a support 1 SMA coil spring 2 bias coil spring 3 traction wire

Claims (6)

[Claims] An actuator having an antagonistic structure in which a shape memory alloy coil spring and a bias coil spring are connected so as to oppose each other, and are configured to output a reciprocating operation in accordance with heating / non-heating of the shape memory alloy coil spring. Wherein the bias coil spring is a superelastic shape memory alloy coil spring formed so as to exhibit a restoring force due to superelasticity at an ambient temperature when the actuator is used. 2. A long object having a portion to be bent,
A shape memory alloy coil actuator according to claim 1 is provided, wherein the shape memory alloy coil actuator is attached to a long object so as to connect both ends of the portion to be bent directly or via a pulling wire, A swing structure, wherein a portion to be bent in accordance with a reciprocating operation of the actuator performs a swing operation. 3. The swing structure according to claim 2, wherein a plurality of the shape memory alloy coil actuators are provided in parallel so as to swing a portion to be bent in different directions. 4. The shape memory alloy coil actuator has a configuration in which a shape memory alloy coil spring and a bias coil spring are connected in series, and when the shape memory alloy coil spring contracts, the bias is pulled by the bias. 3. The swing structure according to claim 2, wherein the coil spring is extended. 5. A bias coil spring of the shape memory alloy coil actuator is attached to the elongated object so as to be located on a side opposite to the shape memory alloy coil spring of the actuator with respect to a longitudinal axis of the elongated object. A configuration in which the shape memory alloy coil spring and the bias coil spring are connected in parallel via a long object, and when the shape memory alloy coil spring contracts, the bias coil spring is extended by being pulled by the bent long object. 3. The swing structure according to claim 2, wherein 6. The shape memory alloy coil spring of the shape memory alloy coil actuator is heated and contracted, and one end of the coil spring is connected to one end of the portion to be bent, and The other end is connected to the other end of the coil spring via a pull wire, and the bias coil spring of the actuator is a compression spring, and is elongated along the portion to be compressed by bending of the portion to be bent. Attached to an object,
The swing structure according to claim 2.