JPH0418997B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a rotating device that converts thermal energy into rotational energy using a shape memory alloy.

[Prior art]

Conventional rotating devices use electric motors, hydraulic devices, pneumatic devices, etc. to rotate objects. The disadvantages were that the structure was complex and the weight was large.

On the other hand, various devices have been proposed that utilize the shape memory effect of shape memory alloys to rotate objects, and such rotation devices that utilize shape memory alloys have a simpler structure and lighter weight. It is possible. However, conventional rotating devices using shape memory alloys have disadvantages in that only a small rotational force can be obtained and the operating speed is slow for the reasons explained below.

In other words, in general, when a shape memory alloy attempts to recover from a deformed state to its memorized shape, the shape recovery force is significantly greater when a shape memory alloy is subjected to elongation deformation than when it is subjected to bending or torsional deformation. It is well known that this will happen.

Also, related to this, the speed at which a shape memory alloy recovers from its deformed state to its memorized shape also depends on
It is also well known that when a shape memory alloy is subjected to elongation deformation, it deforms faster than when it is subjected to bending or torsional deformation.

However, conventional rotation devices using shape memory alloys rotate objects by utilizing shape recovery from bending and torsional deformation of the shape memory alloy, and therefore only a small rotational force can be obtained as described above. Moreover, the operating speed was slow.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and provides a rotating device that has a simple structure, can be made lightweight, can obtain a large rotational force, and can increase the operating speed. The purpose is to provide.

[Summary of the invention]

The rotating device according to the present invention includes a first member and a second member that are rotatable relative to each other around a rotation axis extending in one direction, and the first member and the second member are respectively arranged so as to surround the rotation axis. and a plurality of linear shape memory alloys stretched between the first member and the second member, and relatively rotating these members in a predetermined direction. The apparatus includes a means for applying a tensile force to the shape memory alloy to mainly cause elongation deformation to the shape memory alloy by applying a force, and a means for heating the shape memory alloy.

In the present invention, the shape memory alloy undergoes elongation deformation when the temperature is lower than a certain temperature range. However, when the shape memory alloy is heated to a certain temperature range, the shape memory effect generates a shape recovery force that tries to return to the memorized length, causing the first and second members to move in the opposite direction from the predetermined direction. Rotate relative to direction.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

1 to 3 show one embodiment of the present invention. One end of a shaft 2 is fixed to the first member 1, and a second member 3 is fixed to the other end of the shaft 2.
is supported rotatably and immovably in the axial direction with respect to the shaft 2. Between the outer periphery of the first member 1 and the outer periphery of the second member 3, there is a linear
A suitable number of shape memory alloys 4 such as Ti--Ni alloy are stretched at equal angular intervals. The shape memory alloy 4 each remembers a straight shape with a predetermined length, and is connected to a current supply device (not shown).

Said second member 3 is rotated relative to the first member 1 by a spring 5 (shown only in FIG. 3).
It is biased in the direction of arrow A (counterclockwise) in the figure. When the shape memory alloy 4 is not heated, the second member 3 is rotated by a certain angle in the direction of arrow A with respect to the first member 1 as shown in FIG. 1 due to the biasing force of the spring 5. In this state, the shape memory alloy 4 is subjected to a tensile force and undergoes elongation deformation compared to the memorized length.

Next, the operation of this embodiment will be explained.

As mentioned above, when the shape memory alloy 4 is not heated, the second member 3 is rotated by a certain angle in the direction of the arrow A as shown in FIG. 1 by the biasing force of the spring 5, and the shape memory alloy 4 has undergone elongation and deformation compared to the memorized length.

However, the shape memory alloy 4
When a current is applied to the alloy 4 and the alloy 4 is heated to a certain temperature or higher by Joule heat, the shape memory alloy 4
shrinks in an attempt to return to its memorized length due to the shape memory effect. As a result, the second member 3 is
The first member 1 is rotated in the direction of arrow B (the opposite direction to the direction of arrow A).

Further, when the current supply to the shape memory alloy 4 is stopped and the alloy 4 is cooled, the second member 3 is again rotated in the direction of arrow A by the biasing force of the spring 5.
The shape memory alloy 4 is again subjected to elongation deformation.

In addition, in this rotating device, as mentioned above, the second member 3 is rotated relative to the first member 1 using the shape recovery force from elongation deformation, so the shape memory alloy 4 is It is not necessarily necessary to store a straight shape as in this embodiment; it is acceptable to store a curved shape as long as a predetermined length is stored.

4 to 6 show other embodiments of the invention.

One end of a shaft 7 is fixed to the first member 6, and a second member 8 is fixed to the other end of the shaft 7.
It is supported rotatably and immovably in the axial direction of the shaft 7.

An appropriate number of alloy support members 9 are interposed between the outer circumference of the first member 6 and the outer circumference of the second member 8, and these alloy support members 9 are independently attached to the shaft 7. is rotatably supported. A portion of the first member 6 has a protrusion 6a having a shape similar to a Soroban ball. Further, the alloy receiving member 9 also has a protrusion 9a due to its shape resembling a Soroban ball.

Between the first member 6 and the second member 8,
An appropriate number of linear shape memory alloys 10 such as Ti--Ni alloys are stretched at equal angular intervals, and these shape memory alloys 10 are in contact with the protrusions 6a and 9a. Note that the shape memory alloy 10 memorizes a straight shape over a predetermined length (however, even in this embodiment, the shape memory alloy 10 may memorize a curved shape). Further, the shape memory alloy 10 is connected to a current supply device (not shown).

The second member 8 is urged in the direction A (counterclockwise) in FIG. 4 relative to the first member 6 by a spring 11 (shown only in FIG. 6).
When the shape memory alloy 10 is not heated, the biasing force of the spring 11 causes the second member 8 to move toward the first member 6 as shown by the arrow A in FIG.
It is rotated by a certain angle in the direction, and in this state,
The shape memory alloy 10 is subjected to a tensile force and undergoes elongation deformation compared to the memorized length.

Next, the operation of this embodiment will be explained.

As mentioned above, when the shape memory alloy 10 is not heated, the second member 8 is rotated by a certain angle in the direction of arrow A as shown in FIG. 4 by the urging force of the spring 11, and the shape memory Alloy 10 has undergone elongation deformation compared to its memorized length. In this embodiment, when the second member 8 is rotated in the direction of arrow A, the shape memory alloy 10 becomes roughly spiral and comes into contact with the protrusion 9a of each alloy receiving member 9 (however, each protrusion 9a In between, shape memory alloy 10
is almost linear).

However, the shape memory alloy 10
When a current is applied to the alloy 10 and the alloy 10 is heated to a certain temperature or higher due to Joule heat, the alloy 10 shrinks in an attempt to return to its memorized length due to the shape memory effect. Therefore, the second member 8 is rotated in the direction of arrow B (opposite to the direction of arrow A) as shown in FIG.

Further, when the current supply to the shape memory alloy 10 is stopped and the alloy 10 is cooled, the second member 8 is again rotated in the direction of arrow A by the biasing force of the spring 11, and the shape memory alloy 10 is deformed again. Given.

Further, in the above embodiment, the shape memory alloy 4 is
Since no means is provided to prevent the second member 3 from moving to the side, when the second member 3 is largely rotated in the direction of arrow A (the direction in which the shape memory alloy 4 undergoes elongation deformation), the shape memory alloy 4 will move toward the shaft 2. The second member 3 cannot rotate with respect to the first member 1 in a large range because the shape memory alloys 4 may get caught or come into contact with each other, making it difficult to rotate smoothly.

However, in this embodiment, since the alloy receiving member 9 is provided, the shape memory alloy 10 cannot move toward the shaft 7, so the above-mentioned disadvantage does not occur, and the second The rotatable range of the member 8 can be increased.

Further, the first member 6 and the alloy receiving material 9 may all be integrated, but as in this embodiment, the alloy receiving material 9 may be divided so that each alloy receiving material 9 can rotate independently of each other. By doing so, it is possible to reduce the frictional force that acts between the shape memory alloy 10 and the first member 6 via the alloy receiving member 9 and the shaft 7, and to reduce the loss of force.

Further, in this embodiment, a part of the first member 6 and the alloy receiving member 9 have a shape similar to a Soroban ball, but these members may have a cylindrical shape.
However, in that case, since the contact area between the shape memory alloy 10, the first member 6, and the alloy support material 9 becomes large, (a) the shape memory alloy 10, the first member 6, and the alloy support material 9 becomes large, and the loss of force becomes large.

(b) During heating, heat loss due to heat conduction from the shape memory alloy 10 to the first member 6 and the alloy receiving member 9 increases, and the heating rate of the shape memory alloy 10 becomes slower, and when cooling, the shape memory alloy 1
The contact between the shape memory alloy 10 and the first member 6 and the alloy receiving member 9 impedes heat dissipation of the shape memory alloy 10, resulting in a slow cooling rate. Therefore, the operating speed of the device becomes slow both during heating and cooling.

This inconvenience arises.

However, if the first member 6 and the alloy receiving member 9 are shaped as in this example, the shape memory alloy 1
The contact area between the shape memory alloy 10 and the first member 6 and the alloy receiving material 9 becomes smaller, the frictional force generated between the shape memory alloy 10 and the first member 6 and the alloy receiving material 9 becomes smaller, and the force is reduced. Loss becomes smaller. In addition, during heating, heat loss due to heat conduction from the shape memory alloy 10 to the first member 6 and the alloy receiving member 9 is reduced, and the heating rate of the shape memory alloy 10 becomes faster, and during cooling, the Heat radiation is the first member 6
Also, the cooling rate of the shape memory alloy 10 becomes faster because it is less hindered by the alloy receiving material 9. Therefore, the operating speed of the device is increased both during heating and cooling.

Furthermore, in each of the above embodiments, a spring is used to apply a tensile force to the shape memory alloy to give the alloy elongation deformation, but the means for applying a tensile force to the shape memory alloy is other than the spring. It's okay,
For example, two rotating devices as shown in each of the above embodiments may be used.
separately prepared, and connect the second members to each other (in this case, the second members of both devices may be integrated),
When the shape memory alloy of one rotating device is heated and contracts, and the device and the second member of the other rotating device are rotated in one direction, the shape memory alloy of the other rotating device is subjected to a tensile force. It may also be configured to stretch and deform.

〔Effect of the invention〕

As described above, the rotating device according to the present invention (a) is driven by a shape memory alloy, so the structure can be simplified and the weight can be reduced.

(b) Since shape recovery from elongation deformation of the shape memory alloy is utilized, a large rotational force can be obtained and the operating speed can be increased.

(c) A linear shape memory alloy is arranged between the first member and the second member so as to surround the relative axis of rotation between the first member and the second member, which extends in one direction. Since the structure is such that the shape memory alloys that apply force in the same rotational direction can be easily installed in parallel between the first member and the second member, By increasing the number of rods, it is easy to further increase the rotational force and increase the operating speed.

This excellent effect can be obtained, and it is suitable for use in, for example, a manipulator.

[Brief explanation of drawings]

1 and 2 are perspective views showing one embodiment of the rotating device according to the present invention, FIG. 3 is a sectional view showing the embodiment, and FIGS. 4 and 5 are other views of the rotating device according to the present invention. FIG. 6 is a perspective view showing the embodiment, and FIG. 6 is a sectional view showing the embodiment. DESCRIPTION OF SYMBOLS 1, 6... First member, 2, 7... Shaft, 3, 8... Second member, 4, 10... Shape memory alloy, 5, 11...
Spring.

Claims (1)

[Claims] 1. A first member and a second member that are rotatable relative to each other around a rotating shaft extending in one direction, and the first member and the second member, respectively, arranged so as to surround the rotating shaft. By applying a force to relatively rotate these members in a predetermined direction between a plurality of linear shape memory alloys stretched between the first member and the second member. . A rotating device comprising means for applying a tensile force to the shape memory alloy to mainly cause elongation deformation to the shape memory alloy, and means for heating the shape memory alloy.