JPS6326279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermo-mechanical energy conversion device that converts thermal energy into mechanical energy using a shape memory alloy.

This type of device utilizes the restoring force (hereinafter referred to as "shape restoring force") that occurs during the process in which the shape memory alloy recovers from its deformed state to its memorized shape. It is well known that when subjected to elongation deformation, the value becomes significantly larger than when subjected to bending or torsional deformation.

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 the process is faster when subjected to elongation deformation than when applied to bending or torsional deformation.

Therefore, in this type of device, it is preferable to apply elongation deformation to the shape memory alloy and utilize the shape recovery force from the elongation deformation.

However, in the past, when trying to apply elongation deformation to a shape memory alloy as described above and utilize the shape recovery force from the elongation deformation, it was not possible to increase the stroke of the movable part of the device, so conventional This type of device typically applies bending deformation (and torsional deformation) to a shape memory alloy, and utilizes the shape recovery force from the bending deformation (and torsional deformation). For this reason, it has the disadvantage that only a relatively small force can be generated and the operating speed is relatively slow.

The present invention has been made in view of these circumstances, and utilizes the shape recovery force of shape memory alloys from elongation deformation, and can increase the stroke of the movable part, making it suitable for use in manipulator arms, etc. It is an object of the present invention to provide a suitable thermo-mechanical energy conversion device.

A thermo-mechanical energy conversion device according to the present invention that achieves such an object includes two members rotatably connected to each other, a shape memory alloy wrapping portion, and one end connected to the two members. a linear shape memory alloy whose other end is attached to one of the two members, the other end of which is attached to the other of the two members, and whose middle portion is wrapped around the shape memory alloy wrapping portion; and means for applying a tensile force to.

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

In FIGS. 1 and 2, one end of a structural member 1 and a structural member 2 are connected to each other by a shaft 3 so as to be relatively rotatable. The structural member 1
A pulley-shaped shape memory alloy wrapping material 4 constituting a shape memory alloy wrapping portion in this embodiment is fixed to the shaft 3 with its center aligned with the shaft 3.

Reference numeral 5 denotes a linear shape memory alloy such as a Ti-Ni alloy, and this shape memory alloy 5 is attached at one end near the end opposite to the shaft 3 of the structural member 1, and at the other end. A section is attached near the end of the structural member 2 on the opposite side to the shaft 3, and an intermediate section is wrapped around a shape memory alloy wrapping material 4. Here, the shape memory alloy 5 memorizes a straight shape as shown in FIG. 3 by being subjected to a predetermined shape memory treatment, and the total length of the same alloy 5 in this memorized shape is L. It's summery.

A tension spring 6 is interposed between the structural members 1 and 2. In other words, the shape memory alloy 5 is biased in a direction in which a tensile force is applied to the shape memory alloy 5. Also,
The shape memory alloy 5 is connected to a current supply device 7 at both ends thereof.

Next, the operation of this embodiment will be explained.

First, in this embodiment, since the portion of the shape memory alloy wrapping material 4 that comes into contact with the shape memory alloy 5 is circular, when the angle α between the structural members 1 and 2 reaches a certain value, the As shown in Figure 4, the angle formed by the two straight lines connecting the shaft 3 and both ends A and B of the arc formed by the contact area between the shape memory alloy 5 and the shape memory alloy wrapping material 4 is
If it becomes θ [rad], then the shape memory alloy 5 will have undergone elongation deformation by ΔL=r・θ (1) compared to the memorized shape shown in Fig. 3 (however,
r is the radius of the portion of the shape memory alloy wrapping material 4 that comes into contact with the shape memory alloy 5).

Now, when no current is applied to the shape memory alloy 5 from the energizing device 7 and the alloy 5 is cooling, the angle α between the structural members 1 and 2 is minimized by the force of the spring 6. (the state shown in FIG. 1), the angle θ becomes maximum. Therefore, as is clear from equation (1), at this time, the elongation ΔL of the shape memory alloy 5 is at its maximum.

Next, the energizing device 7 causes the shape memory alloy 5 to
When a certain amount of current is applied, the alloy 5 is heated by Joule heat, reaches a certain temperature or higher, starts phase transformation, and attempts to return to its memorized shape due to the shape memory effect.

Therefore, in terms of the expansion and contraction direction, the shape memory alloy 5 tries to contract so that its total length becomes L (in other words, so that ΔL becomes 0).

Therefore, if the structural member 2 is now fixed, the structural member 1 is rotated counterclockwise in the figure against the spring 6, as shown by the dashed line in FIG. The angle α between parts 1, 2 is enlarged.

At this time, some shape recovery from the bending deformation of the shape memory alloy 5 is also observed, but the specific gravity of the shape recovery force from the bending deformation of the shape memory alloy 5 contributing to the operation of the device is very small.

In this way, this thermo-mechanical energy conversion device utilizes the shape recovery force from the elongation deformation of the shape memory alloy 5, so that the structural member 1 can be driven at high speed with a very large force.

Furthermore, if the elongation ΔL of the shape memory alloy 5 is too large, plastic deformation will occur and complete shape recovery will not occur. In the conversion device, the minute change in ΔL is greatly magnified and becomes the displacement of the structural member 1.
The stroke of the structural member 1 can be increased.

Note that when the current supply by the current supply device 7 is stopped and the shape memory alloy 5 is cooled, the structural member 1 is rotated clockwise in the figure by the force of the spring 6, and the above-mentioned angle α
becomes smaller again.

In addition, the elongation ΔL of the shape memory alloy 5 during heating, and therefore the angle α between the structural members 1 and 2, are the progress state of phase transformation of the shape memory alloy 5, and the magnitude of the thermal energy input to the shape memory alloy 5. corresponds to
Therefore, by controlling the magnitude of the current flowing from the current supply device 7 to the shape memory alloy 5, the angle α between the structural members 1 and 2 can be controlled.

In addition, in the above embodiment, the shape memory alloy wrapping material 4
Of these, the part around which the shape memory alloy 5 is wrapped is circular, and its center is aligned with the axis 3, but the part of the shape memory alloy wrapping material 4 does not necessarily have to be circular, There is no need for its center to coincide with axis 3.

However, depending on the shape of the part of the shape memory alloy wrapping material 4 and the positional relationship between the part and the shaft 3, the relationship between the angle α and the elongation ΔL, and furthermore, the above when the shape memory alloy 5 is energized. The characteristic curve showing the relationship between the angle α and the torque generated by the shape memory alloy 5 changes.

In addition, in the above embodiment, the shape memory alloy wrapping material 4
Although it is a separate member from the structural member 1, the shape memory alloy wrapping material 4 may be provided integrally with the structural member 1.

Furthermore, the shape memory alloy wrapping material 4 may not be fixed to the structural member 1, but may be rotatable with respect to either of the structural members 1 and 2.

FIG. 5 shows another embodiment of the invention. One ends of the structural members 8 and 9 are connected to each other by a shaft 10 so as to be relatively rotatable. Shape memory alloy wrapping members 11 and 12 are attached to portions of these structural members 8 and 9 near the shaft 10, respectively. In addition, these shape memory alloy wrapping materials 11, 1
2 may be rotatable relative to the structural members 8 and 9, respectively, or may be fixed.

13 is a linear shape memory alloy, one end of which is attached near the end of the structural member 8 on the opposite side to the axis 10, and the other end thereof is attached near the end of the structural member 9 on the opposite side to the axis 10. At the same time, the intermediate portion is wrapped around shape memory alloy wrapping members 11 and 12. Here, the shape memory alloy 13 is
As in the case of the previous embodiment, a straight shape is memorized.

A tension spring 14 is provided between the structural members 8 and 9.
is interposed, and this spring 14 moves the structural members 8 and 9 in a direction that reduces the angle between the structural members 8 and 9, that is, in a direction that applies a tensile force to the shape memory alloy 13. It is energizing. Further, the shape memory alloy 13 is connected to an energizing device (not shown) at both ends thereof.

In this embodiment as well, the shape memory alloy 13 is subjected to elongation deformation by the force of the spring 14. When the shape memory alloy 13 is energized from the energizing device in this elongated and deformed state and the alloy 13 is heated, the same alloy 13 is heated in the same manner as in the above embodiment. contracts in an attempt to return to its memorized shape length, and the structural members 8 and 9 are driven against the spring 14.

As a result, the same effects as in the embodiment described above can be obtained.

FIG. 6 shows yet another embodiment of the invention.
Structural members 16 and 17 have their one ends connected to each other.
They are connected by a shaft 18 so as to be relatively rotatable. Further, the intermediate portion of the structural member 16 and one end portion of the structural member 19 are coupled via a shaft 20 so as to be relatively rotatable. Furthermore, the structural member 19
The other end of the structural member 21 and the other end of the structural member 21 are relatively rotatably connected by a shaft 22, and the other end of the structural member 21 and the intermediate portion of the structural member 17 are connected to each other by a shaft 23. are relatively rotatably connected.

Shape memory alloy wrapping members 24, 25, and 26 are provided near the shafts 20, 22, and 23, respectively. Here, these shape memory alloy wrapping materials 2
4, 25, 26 are structural members 16, 17, 19,
21, or may be rotatable relative to any of these structural members.

27 is a linear shape memory alloy; one end of the shape memory alloy 27 is attached near the end opposite to the shaft 18 of the structural member 16, and the other end is attached to the opposite end of the structural member 17. It is attached near the end opposite to the shaft 18, and its intermediate portion is wrapped around shape memory alloy wrapping members 24, 25, and 26. Here, the shape memory alloy 27 is
As in each of the above embodiments, a straight shape is memorized.

A tension spring 28 is interposed between the structural members 16 and 17, and this spring 28 holds the structural members 16 and 17 at an angle _α1 between the structural members 16 and 17. The force is applied in the direction in which both the angle α ₂ between the structural members 16 and 19 and the angle α ₃ between the structural members 21 and 17 become smaller, that is, in the direction in which a tensile force is applied to the shape memory alloy 27.

The shape memory alloy 27 is connected to a power supply device (not shown) at both ends thereof.

In this embodiment, as in the previous embodiments, when a current is passed from the current supply device to the shape memory alloy 27 and the alloy 27 is heated to a certain temperature or higher, the length in the memorized shape changes. As they try to contract, the structural members 16, 17, 19, 21 are each rotated in a direction in which the angles α ₁ , α ₂ and α ₃ become larger. As a result, the same effects as in each of the embodiments described above can be obtained.

In addition, in each of the above examples, the shape memory alloy is heated by electrical heating, but in the present invention, the shape memory alloy may be heated by other methods such as irradiation with a laser beam or ordinary light. .

Furthermore, in each of the above embodiments, a spring is used to apply a tensile force to the shape memory alloy, but the tensile force is applied to the shape memory alloy by gravity or other forces other than the spring force. Needless to say, it is also good to have a configuration in which

As described above, the thermo-mechanical energy conversion device according to the present invention utilizes the shape recovery force from elongation deformation of the shape memory alloy, so it is possible to generate a large force and increase the operating speed. Moreover, the excellent effect of increasing the stroke of the movable part can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the thermo-mechanical energy conversion device according to the present invention, FIG. A front view showing the memorized shape of the shape memory alloy, FIG. 4 is an enlarged front view showing the shape memory alloy wrapped around the shape memory alloy wrapping material in the same embodiment, and FIG. 5 is another embodiment of the present invention. FIG. 6 is a front view showing still another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1, 2... Structural member, 3... Shaft, 4... Shape memory alloy wrapping material, 5... Shape memory alloy, 6... Spring, 8, 9...
Structural member, 10... Shaft, 11, 12... Shape memory alloy wrapping material, 13... Shape memory alloy, 16, 17, 19
...Structural member, 20...Shaft, 21...Structural member, 22,
23... Shaft, 24, 25, 26... Shape memory alloy wrapping material, 27... Shape memory alloy, 28... Spring.

Claims (1)

[Claims] 1. Two members rotatably connected to each other, a shape memory alloy wrapping portion, and one end thereof connected to the above-mentioned 2 members.
a linear shape memory alloy whose other end is attached to one of the two members, and whose middle portion is wrapped around the shape memory alloy wrapping portion; A thermo-mechanical energy conversion device comprising means for applying a tensile force to a memory alloy.