JPH0377389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in actuators using shape memory alloys.

[Conventional technology and its problems]

Various actuators using shape memory effects such as Ni-Ti alloys are known. In many of these, shape memory alloys having unidirectional properties are used because if the shape memory alloy itself has two-way properties, it is not possible to accurately set the shapes on the high and low temperature sides. Methods for obtaining bidirectional characteristics using a unidirectional shape memory alloy include a bias method and a differential bidirectional element. These methods utilize the properties of being soft at low temperatures and hard at high temperatures, such as the bias method shown in FIG. 4.

That is, a shape memory alloy coil 11 and a coil spring 12 are arranged in parallel to a central axis 14 via a stopper 13, and when the temperature is low, the shape memory coil has a contracted shape due to the bias force of the coil spring. When the shape memory coil is heated to a high temperature, it overcomes the bias force of the coil spring and stretches, pushing the stopper to the right in the drawing.
The central axis moves to the right. When the heating is stopped and the temperature becomes low, the bias force of the coil spring becomes stronger, pushing back the shape memory coil and moving the stopper and central axis to the left. By repeating such operations, driving forces in two directions are applied to the central shaft.

Also, in the differential type, a shape memory coil is used instead of the coil spring 12 shown in Fig. 4, and the two left and right shape memory coils are alternately heated to obtain driving force in two directions in the same way as above. . However, both the bias type and the differential type use the property of returning to the memorized shape when heated, so they return to the original position when the temperature becomes low. When maintaining the moved position, it is necessary to maintain that temperature for the period necessary to maintain the memorized shape.
That is, in the bias type shown in FIG. 4, if the stopper is moved to the right and the temperature is to be maintained for a certain period of time, it is necessary to keep the shape memory coil at a certain temperature for a certain period of time. Normally, methods for heating shape memory coils include heating the coil by directly applying electricity to the coil, heating with hot air, etc. However, current control devices, adjustment devices such as timers, and hot air heating devices are required. However, the cost is high, and there are also restrictions on the installation location, which pose major obstacles to the use of this type of drive device.

[Problem that the invention seeks to solve]

As a result of considering the above problem, the inventor has found that
The shape memory alloy is heated to return to the desired shape and driven in one direction, and this state is maintained even when the heating is stopped and cooled. Then, when the other shape memory alloy is heated, it is driven in the other direction. This state is maintained even if the heating is stopped and the device is cooled. In other words, we have developed an actuator that can select any two positions and operates reliably even at low temperatures.

[Means and actions for solving problems]

The present invention memorizes a plurality of shape memory alloy plates in an arcuate or conical shape, inverts one or more shape memory alloy plates to be approximately symmetrical to the memorized shape, and forms a central portion of the shape memory alloy plate. It is characterized by being installed in an independent heated chamber connected by a shaft and partitioned by a partition wall, and the shape memory alloy plates in the independent chamber are alternately heated to return to the memorized shape, thereby driving the shaft in two directions. It is an actuator that

That is, as shown in FIG.
A rectangular plate of shape memory alloy made of alloy etc.
The shape is memorized into an arched shape as shown in FIG. 1a. This is inserted into the shaft 4 through the spacer 3 in parallel with 1 inverted symmetrical shape to the memorized shape as shown in 1 in Fig. 1b and 2 in parallel with the arched shape memorized. be. The upper and lower ends of the memory alloy plates 1 and 2 are fixed by fixtures 5 and 5', and the memory alloy plates 1 and 2 are placed in an independent heating chamber separated by a partition wall, and each shape memory alloy plate is electrically heated. The actuator is physically and thermally insulated. To explain this operation, see Figure 1b.
When the shape memory alloy plates 1 and 2 are stable at low temperatures in the state shown in FIG. Returns to the original memorized shape. At this time, the shape memory alloy 2 jumps from the memorized shape of b to the shape of c, buckles, and reverses, and even if the shaft 4 is driven to the right, stops heating, and is cooled, it remains stable in this state. Next, when the shape memory alloy plate 2 is heated in this state, the shape memory alloy plate 2 returns to the memorized original shape as shown in FIG. The shaft 4 is driven to the left and remains stable in this state. By repeating the above operations, it becomes possible to provide intermittent or continuous drive in two directions to the shaft. However, in the present invention, at least one of the shape memory alloy plates is inverted from its memorized shape and combined, so that it jumps, inverts, and becomes buckled during operation, so that a stable stationary state can be maintained during cooling.

The number of shape memory alloy plates used in the present invention can be two or more, and it is preferable in terms of force balance during operation that half of these plates are reversed from the memory shape and combined. Further, instead of the rectangular shape, a disc shaped like a cone may be used.
In addition to Ni-Ti alloys, shape memory alloys include
Ni-Ti alloys with added tertiary elements such as Fe and Co,
In addition to Cu-based alloys such as Cu-Al-Ni and Cu-Au-Zn, commonly used shape memory alloys can be used. Further, as the thermal fluid for heating the shape memory alloy plate, commonly used fluids such as heating gas fluid and hot water are used.

〔Example〕

An embodiment of the present invention will be described below.

As shown in Figure 2, shape memory alloy plates 1 and 2
A shaft 4 passes through the center of the shaft, a spacer 3 is fixed to the center of the shaft, and both ends of the spacer regulate the distance between the shape memory alloy plates 1 and 2. In addition, the upper and lower ends of the shape memory alloy plates 1 and 2 are made of synthetic resin base 6 by integral injection molding or the like.
embedded within. The base body 6 is provided with a central partition wall 7, and the internal space of the base body 6 is divided into spaces 8, 8'.
It is divided into 2 minutes. A shape memory alloy plate 1 is provided in the space 8, and a shape memory alloy plate 2 is provided in the space 8'. port 10,
10' is provided.

The memorized shape of the shape memory alloy plate 1 shown in FIG. 2 is obtained by inverting the memorized shape shown in FIG. 1 a into a symmetrical shape at room temperature as shown in FIG. 1 b. One of the shape memory alloy plates 2 incorporates the shape memorized.

Although this actuator is stably stationary at room temperature in the state shown in Fig. 2, heated gas is introduced into the space 8 from the heated gas inlet port 9 to heat the shape memory alloy plate 1 therein above the transformation point. When heated to a temperature of , the shape memory alloy plate 1 returns to its memorized shape and is reversed to take the shape shown in FIG. 3. At this time, shaft 4
The spacer 3 fixed to the shape memory alloy plate 2 is pushed to the right, the shape memory alloy plate 2 is flipped and reversed, and buckled in the opposite direction to the memorized shape, and the shaft moves to the right and remains stable in this state. This state does not return to its original state even when the heated gas is removed from the heated gas outlet port 10 and the space 8 is cooled, because the shape memory alloy plate is in a buckled state. That is, even if heating is interrupted, it is possible to maintain the drive position in one direction.

Next, heated gas is introduced into the space 8' from the heated gas inlet port 9' in FIG. 3 and the shape memory alloy plate 2 therein is heated to a temperature higher than the transformation point. The shaft returns to its original shape and reverses as shown at 2 in Figure 2, and the shaft moves to the left and comes to a stable standstill. In this way, shape memory alloy plates 1 and 2
By alternately heating the shaft, the shaft can be driven intermittently or continuously.

In the above, an example was explained in which the shape memory alloy plate 1 is inverted from the memorized shape and combined, but either 1 or 2 alloy plates may be inverted and assembled, and the initial heating should be applied to the inverted alloy. For example, since the alloy returns to its original shape, the force causes another alloy plate to flip over and become buckled, and then by alternately heating it, drive in two directions can be obtained.

〔effect〕

As explained above, according to the present invention, by alternately heating a plurality of shape memory alloy plates, the shape can be reversed and the shaft can be moved to provide reciprocating motion in two directions, and the heating can be stopped to reduce the temperature to a low temperature. It can maintain its position even if Furthermore, it is possible to select and maintain two necessary positions, which has extremely remarkable effects.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the operating state of the actuator of the present invention, FIGS. 2 and 3 are side sectional views showing one embodiment of the present invention, and FIG. 4 is the operating state of the conventional actuator. FIG. 1... Shape memory alloy plate that is inverted and combined, 2...
...Shape memory alloy plate, 3,3'...Spacer, 4
...Shaft, 5...Fixing tool, 6...Base, 7...
...Partition wall, 8, 8'... Space, 9, 9'... Gas inlet port, 10, 10'... Gas outlet port.

Claims (1)

[Claims] 1 A plurality of shape memory alloy plates are memorized in an arcuate or conical shape, one or more of these shape memory alloy plates is inverted to be approximately symmetrical to the memorized shape, and a shaft in the center of the shape memory alloy plate is An actuator characterized in that the actuator is arranged in an independent heated chamber that is connected to the inner chamber and partitioned by a partition wall, and that the shape memory alloy plates in the independent chamber are heated alternately to return to the memorized shape and drive the shaft in two directions. Yueter.