JPS59170508A - Actuator - Google Patents

Abstract

PURPOSE:To provide an actuator capable of performing a repetitive operation under a fast speed and capable of obtaining a substantial deformation irrespective of a small sectional area by a method wherein a bellows type shape memory alloy pipe is heated and cooled to make a deformation of the shape thereof. CONSTITUTION:A pipe 1 made of shape memory alloy is formed as a bellows to make an actuator 3. In this case, the pipe 1 is processed to perform a shape memory treatment to have a bent shape at a temperature higher than a reverse- transformation point, for example. A usual coil spring 2 is arranged within the pipe 1 to assist the linear variation at a temperature lower than the transformation point. With the foregoing arrangement, for example, nitrogen gas of low temperature is caused to flow in the pipe 1 and a repetitive energization of the pipe 1 is applied to perform the heating and cooling thereof, resulting in that the pipe 1 is rapidly varied in its shape. Therefore, it is possible to utilize the actuator as various types of actuators under a repetitive operation of the variation in shape of the pipe 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to actuators that utilize shape memory alloy members.

＆ Stand 1 "Self" Order 1 Conventionally, various actuators have been proposed using the shape memory effect of shape memory alloys. However, conventional actuators made of shape memory alloy members use shape memory alloy members in the shape of round wires or tapes. Shape memory alloy members with these shapes are heated with electricity,
Alternatively, it is operated by heating from the outside.

By the way, in order to return an actuator made of a shape memory alloy member to its original shape, it is necessary to cool it to a temperature lower than the martensitic transformation temperature. however,
In conventional actuators made of shape memory alloy members,
There was a problem that this cooling could not be performed efficiently.

Therefore, when operated repeatedly, it is not possible to cause a rapid change, and it cannot be used in fields where high-speed movement is required.

On the other hand, the force generated by the shape memory effect is proportional to the cross-sectional area of the shape memory alloy actuator. Therefore, if greater force is desired, the cross-sectional area must be increased. However, when the cross-sectional area is increased, the cooling rate decreases, resulting in a decrease in the amount of allowable bending strain for shape recovery. Therefore, conventional shape memory alloy actuators cannot meet the demands for both an increase in force based on shape recovery and an increase in allowable bending strain.

111L disturbance Therefore, it is an object of the present invention to solve the above-mentioned problems and provide an actuator that can be operated repeatedly at high speed and that can obtain a large amount of deformation in relation to its cross-sectional area. .

1L1L Simply put, this invention is an actuator characterized by being made of a bellows-shaped shape memory alloy pipe. That is, the actuator of the present invention is made of a shape memory alloy pipe having a bellows-like shape, and by forming the pipe into a bellows-like shape, it is possible to increase the cooling rate and to achieve larger bending deformation.

The "shape memory alloy" used in this invention is an alloy member having a shape memory effect, and this shape memory effect is produced by martensitic transformation and reverse transformation.
This is a phenomenon in which, after being deformed at a temperature lower than the transformation temperature, if heated to a higher temperature than the reverse transformation temperature, the material returns to its shape at the high temperature before deformation.

In some cases, the material may exhibit a bidirectional shape memory effect that can memorize the shape to some extent on the low humidity side. As an alloy member exhibiting such a shape memory effect, for example, NI having a composition consisting of 55 Shigeyamao's N1 and 45% by weight of T1
T+gold alloy is known. In addition, Cu-Zn
, Cu-AL, Cu-Zn-AIL, CU
Alloys such as -Ami-NI, Nl-A alloys are also known to have shape memory effects.

Preferably, the bellows-shaped shape memory alloy pipe is heated to a temperature higher than the martensitic transformation temperature by electrical heating to recover its shape. By recovering the shape through electrical heating, the shape memory alloy pipe can be heated with a simple configuration. However, it goes without saying that all known heating means other than electrical heating can be used.

In addition, in the case of an actuator made of a bidirectional shape memory alloy member, if the shape memory alloy pipe is cooled to a temperature lower than the martensitic transformation temperature, it returns to the shape before shape recovery. To achieve this cooling more efficiently, cooling fluid is preferably passed through the shape memory alloy pipe. Various fluids can be used as the cooling fluid, such as air, water, etc. However, more preferably a non-oxidizing gas is used, such as nitrogen gas.

Furthermore, a conventional spring member may be provided within the bellows-shaped shape memory alloy pipe to assist in shape change upon cooling. However, in an actuator made of a unidirectional shape memory alloy member, this spring member is essential.

Other features of the invention will become clear from the following description of embodiments with reference to the drawings.

5- After welding a 0.211 thick NI T1 alloy tape into a pipe shape, we corrugated it to a maximum outer diameter of 8.
■Make a bellows-shaped pipe with a minimum diameter of 5 sm (see Figure 1) and shape it so that it becomes bent as shown in Figure 2 at temperatures higher than the inverse S temperature (approximately 70°C). A pipe 1 which had been subjected to memory treatment was obtained. A normal coil spring 2 is placed inside the pipe 1. This is to assist the bellows-shaped pipe 1 to change into a straight shape at a temperature lower than the variable WA temperature.

Low-temperature nitrogen gas was flowed into the bellows-shaped pipe 1 of the actuator 3 obtained in this way, and the shape memory alloy pipe 1 itself was repeatedly heated and cooled by repeatedly turning on and off the electricity. The shape change is amazing! It was noticed.

[Similar to Example 1, cu-zn-A with thickness Q of 3 mm
A bellows-shaped, ie, corrugated, pipe 1 was created by welding a metal alloy tape. This 6-concert-shaped shape memory alloy vibrator 1 contracts so that it contracts as shown in FIG. 4 when heated and expands when cooled (
(see Figure 3) was subjected to heat treatment. In addition, a coil spring 2 made of a normal metal member was provided inside the shape memory alloy vibrator 1 in order to assist the shape change during elongation.

When low-temperature air was circulated through the shape memory alloy vibe 1 of the actuator 3 obtained in this manner, heating and stopping of electricity supply to the shape memory alloy vibe 1 was repeated, and the actuator 3 responded quickly and repeatedly expanded and contracted. Ta.

As described above, according to the present invention, since the actuator is made of a bellows-shaped shape memory alloy vibrator, the surface area of the shape memory alloy member is large, and therefore the cooling rate is large, so that high-speed repetitive motion can be achieved. Can be done. Further, since it is a bellows-shaped shape memory alloy pipe, it is possible to perform large deformations such as bending in relation to its cross-sectional area.

It is noted that this invention can be used in various fields such as various actuators and solid state engines.

[Brief explanation of drawings]

1 and 2 are longitudinal sectional views showing an embodiment of the present invention, and FIG. 1 is a variation W! Figure 2 shows the shape at a temperature lower than the reverse transformation temperature. 3 and 4 are longitudinal sectional views showing other embodiments of the present invention, with FIG. 3 showing the shape at a temperature lower than the transformation temperature, and FIG. 4 showing the shape at a temperature higher than the reverse transformation temperature. Show shape. DESCRIPTION OF SYMBOLS 1... Bellows shape memory alloy vibe, 2... Spring member, 3... Actuator.

Claims (4)

[Claims] (1) An actuator comprising a serpentine shape memory alloy vibrator. (2) The actuator according to claim 1, wherein the shape of the bellows-shaped shape memory alloy pipe 1 is restored by heating with electricity. (3) In order to cool the bellows-shaped shape memory alloy pipe, a cold! 3. The actuator according to claim 1, wherein the Jl'a body is passed through. (4) A spring member is provided in the bellows-shaped shape memory alloy pipe, thereby causing martensitic transformation 1!
! The shape change when cooling to a lower temperature than the temperature is assisted,
An actuator according to any one of claims 1 to 3.