JPH0375758B2 - - Google Patents

Description

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

[Prior art]

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 desirable 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 and utilize the shape recovery force from the elongation deformation as described above, it was difficult to increase the stroke of the movable part of the device. Bending deformation (and torsional deformation) was applied to shape memory alloys, and the shape recovery force from the bending deformation (and torsional deformation) was utilized. Therefore, it has the disadvantage that only a relatively small force can be generated and the operating speed is relatively slow.

Therefore, the applicant first applied for patent application No. 57-118457.
In this issue, we proposed a thermo-mechanical energy conversion device that utilizes the shape recovery force of a shape memory alloy from elongation deformation, can increase the stroke of a movable part, and is suitable for use in manipulator arms, etc.

In this device, one end side of a linear shape memory alloy is attached to one of two members rotatably connected to each other, and the shape memory alloy is attached to the other of the two members. The other end of the alloy is attached, and the middle part of the shape memory alloy is wrapped around the shape memory alloy wrapping part. The shape recovery force acts in the direction of increasing the angle between the two members.

[Purpose of the invention]

The present invention has been made in view of these circumstances, and utilizes shape recovery from elongation deformation of shape memory alloys, and can increase the stroke of the movable part, and furthermore, the shape recovery force is It is an object of the present invention to provide a thermo-mechanical energy conversion device that acts in a direction that reduces the angle between members.

[Summary of the invention]

The thermo-mechanical energy conversion device according to the present invention comprises:
two members rotatably connected to each other, a shape memory alloy wrapping part, one end side attached to one of the two members, and the other end side attached to the other of the two members. As well as being installed respectively,
The shape memory alloy has a linear shape memory alloy whose intermediate portion is wound around the shape memory alloy wrapping portion, and a means for applying a tensile force to the shape memory alloy, and the shape memory alloy is The above object is achieved by being wrapped around the shape memory alloy wrapping portion in such a manner that as the angle between the two members increases, the elongation deformation of the shape memory alloy increases. .

〔Example〕

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.

5 is a linear shape memory alloy such as a Ti-Ni alloy, and this shape memory alloy 5 has one end attached to the structural member 1, the other end attached to the structural member 2, and an intermediate portion. The shape memory alloy wrapping material 4 is wound around the 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 alloy 5 in this memorized shape
The total length of is L.

Further, the shape memory alloy 5 is wound around the shape memory alloy wrapping material 4 in a cross state, so that when the angle θ between the structural members 1 and 2 increases, the alloy 5 undergoes elongation deformation ΔL is made to grow.

A spring 6 is interposed between the structural members 1 and 2 (see FIG. 2), and this spring 6 biases the structural members 1 and 2 in the direction in which the angle θ becomes larger.

Further, the shape memory alloy 5 is connected to the current supply device 7 at both ends thereof.

Next, the operation of this embodiment will be explained.

When no current is applied to the shape memory alloy 5 from the energizing device 7 and the alloy 5 is cooled, the force of the spring 6 changes the angle θ between the structural members 1 and 2 and the shape memory alloy 5. The elongation ΔL is at its maximum.

Next, when a current of an appropriate magnitude is passed through the shape memory alloy 5 from the energizing device 7, the alloy 5 is heated by Joule heat, reaches a certain temperature or higher, starts phase transformation, and due to the shape memory effect, a third Attempts to return to the memory shape of the figure (straight state).

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 clockwise in the figure against the spring 6, as shown by the dashed line in FIG. The angle θ between 1 and 2 becomes smaller.

Note that since the shape memory alloy 5 is linear, its shape recovery force from bending deformation is small, so the shape memory alloy 5 exhibits only slight shape recovery with respect to bending deformation.

Since this thermo-mechanical energy conversion device utilizes the shape recovery force of the shape memory alloy 5 from elongation deformation as described above, 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, so ΔL cannot be increased beyond a certain level, but this thermo-mechanical energy In the conversion device, the minute deformation of 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 counterclockwise in the figure by the force of the spring 6, and the angle θ becomes large again.

In addition, the elongation ΔL of the shape memory alloy 5 during heating, and therefore the angle θ 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 θ between the structural members 1 and 2 can be controlled.

In addition, in the above embodiment, the shape memory alloy wrapping material 4
The part around which the shape memory alloy 5 is wrapped is circular, and its center is aligned with the shaft 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.

Then, depending on the shape of the portion of the shape memory alloy wrapping material 4 and the positional relationship between the portion and the shaft 3, the relationship between the angle θ and the elongation ΔL, and furthermore, the The characteristic curve showing the relationship between the angle θ and the torque generated by the device can be varied.

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.

Alternatively, the shape memory alloy wrapping material 4 is made a separate member from the structural member 1, and the shape memory alloy wrapping material 4 is not fixed to the structural member 1, and the wrapping material 4 is attached to either the structural member 1 or 2. It may also be rotatable.

Furthermore, in the above embodiments, 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 by irradiation with laser light or ordinary light.

Further, in the above embodiments, a spring is used to stretch and deform the shape memory alloy, but it goes without saying that a configuration in which the shape memory alloy is stretched and deformed by gravity or other forces other than the spring force may also be used. stomach.

〔Effect of the invention〕

As described above, the thermo-mechanical energy conversion device according to the present invention utilizes the shape recovery from elongation deformation of the shape memory alloy, and can increase the stroke of the movable part, and furthermore, the shape recovery force is 2.
This provides an excellent effect of acting in the direction of reducing the angle between the two members.

[Brief explanation of drawings]

Fig. 1 is a front view showing an embodiment of the thermo-mechanical energy conversion device according to the present invention, Fig. 2 is a plan view showing the embodiment, and Fig. 3 shows the memorized shape of the shape memory alloy in the embodiment. FIG. DESCRIPTION OF SYMBOLS 1, 2... Structural member, 3... Shaft, 4... Shape memory alloy wrapping material, 5... Shape memory alloy, 6... 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; means for applying a tensile force to the memory alloy,
The shape memory alloy is wound around the shape memory alloy wrapping portion in such a manner that as the angle between the two members increases, elongation deformation of the shape memory alloy increases. Thermo-mechanical energy conversion device.