JPS63205467A - Actuator - Google Patents

Abstract

PURPOSE:To obtain a reciprocating motion in dual direction by electrifying a a surface heating element provided on the surface of a single or plural number of alloy plate, which is or are one or some of the plural number of shape memory alloy plate to be made memorize in a bow shape or the like, and which is to be reversed to be symmetrical to a memorized shape and combined in parallel with a shaft. CONSTITUTION:A shape memory alloy plate 1 composed of Ni-Ti alloy in a bow shape is built in after reversing it to be symmetrical to a memorized shape under a normal temperature, and a memory shape alloy plate 2, which is composed of the same material and the same bow shape as the shape memory alloy plate 1, is built in with the memory of this shape. Further, the memory alloy plates 1 and 2, having surface heating elements 5 and 5' adhered to their surface, are at a stable standstill under a normal temperature. When the surface heating element 5 is electrified and heated, the memory alloy plate 1 is heated, is made to return to its original shape, is made to turn reversely and move to the right as shown with dotted line B. Simultaneously, the shape memory alloy plate 2 jumps as shown with dotted line B', makes a reverse turn and makes a shaft 4 to move to the right and stabilize it as well as to bend it in the direction opposite to the memorized shape. Next, the surface heating element 5' is electrified, heated and returned to the original position at left following the same operation as in the case of the surface heating element 5. Thereafter, a drive in dual direction can be obtained by heating the surface heating element alternately.

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. 3.

That is, the shape memory alloy coil (2) and the coil spring (12
) are placed in parallel with the shaft (4) via the stopper (3), and when the temperature is low, the shape memory coil is in a contracted shape due to the coil spring's pie spacing.
When the shape memory coil is heated to a high temperature, it overcomes the coil spring's bias and expands, pushing the stopper back to the right in the drawing, and the shaft moves to the right. When the heating is stopped and the temperature becomes low, the coil spring's piascus becomes stronger, pushing back the shape memory coil and moving the stopper and shaft to the left. By repeating these operations, driving force in two directions is obtained on the shaft.

In addition, the differential type uses a shape memory coil instead of the coil spring (12) in Figure 3, 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. It is. However, both the bias type and the differential type utilize 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. 3, 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 maintain 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, hot air heating devices, etc. are required, and therefore the cost is high. Due to the high cost and restrictions such as installation location, this type of drive device has been a major obstacle in its use.

[Problems to be Solved by the Invention] As a result of studying the above-mentioned problems, the inventor of the present invention discovered that the shape memory alloy can be heated to return to the required shape and driven in one direction, and even if the heating is stopped and the alloy is cooled. This state is maintained, and when the other shape memory alloy is then heated, it is driven in the other direction, and this state is maintained even when the heating is stopped and cooled. In other words, we have developed an actuator that can select any two positions even at low temperatures.

[Means and effects for solving the problems] The present invention memorizes a plurality of shape memory alloy plates in an arcuate or conical shape, and inverts one or more of these shape memory alloy plates to a shape symmetrical to the memorized shape. A planar heating element is provided on the surface of the shape memory alloy plate, and electricity is applied to the planar heating element to alternately heat and reverse the shape memory alloy plate to drive the shaft in two directions. This actuator is characterized by the ability to

That is, the present invention uses a rectangular plate of a shape memory alloy made of Ni-Ti alloy as shown in FIG.
The shape is memorized into an arched shape as shown in the figure.

As shown in (1) in Fig. 1 (1)), a stopper (3) is placed in parallel with one inverted symmetrical shape to the memorized shape and the arched shape memorized (2). through the shaft (
4). and memory alloy plate (1),
(2) is provided with planar heating elements (5) and (5') on its surface, and shape memory alloy plates (1) and (2) can be heated by applying electricity to the planar heating elements. The shape memory alloy plate is electrically and thermally insulated and used as an actuator. Note that shape memory alloy plate (1), (
The upper and lower ends of 2) are fixed by fixtures (7) and (7'). To explain this operation, when the shape memory alloy plates (1) and (2) are stable at low temperatures in the state shown in Fig. 1(b), the sheet heating element (5) is energized and the shape memory alloy plate (1) is heated. When heated to a predetermined temperature, the shape memory alloy plate (1) returns to its original memorized shape as shown in FIG. 1(C). At this time, the shape memory alloy (2) jumps from the memory shape of (b) as shown in (C), buckles and reverses, and the shaft (4)
) remains stable in this state even if it is driven to the right to stop heating and cool down. Next, in this state, when the sheet heating element (5') is energized and the shape memory alloy plate (2) is heated, the shape memory alloy plate (2) returns to its original memorized shape as shown in Figure 1(a). Returning to , the shape memory alloy plate (1) jumps, buckles, and reverses, and 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, since the present invention is a combination in which at least one of the shape memory alloy plates is reversed from the memorized shape, this jumps and reverses during operation and becomes a buckled state, 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 inverted 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 Fe,
Ni-Ti alloys containing a third element such as Co, and Cu-A/l! In addition to Cu-based alloys such as -Ni and Cu-Au-Zn, commonly used shape memory alloys can be used. In addition, sheet heating elements include those made by printing copper, carbon, or other heat-generating substances on a flexible, heat-resistant film made of polyethylene, polyester, nylon, ethylene vinyl acetate, etc., or other ordinary sheet heating elements. can be used.

〔Example〕

An embodiment of the present invention will be described below.

As shown in Figure 2 (a) and (b), planar heating elements (5) and (5') are placed on the surfaces of arcuate shape memory alloy plates (1) and (2) made of Ni-Ti alloy. The shaft (4) is passed through the small hole in the center of each of the shafts, and the stopper (3) is attached by caulking or the like. Furthermore, insulators (7) and (7'
) are provided with terminals (8) and (8') insulated by the insulating block (9) to supply electricity to the planar heating element.
) and (9') are firmly assembled to the case (10) and (10') by a plurality of bolts (11). Note that the shaft and stopper are made of insulating material or have been subjected to necessary insulation treatment.

The combination of the shape memory alloy plates shown in Fig. 2 above is shown in Fig. 1(a).
The shape memory alloy plate (2) is formed by inverting the memorized shape shown in FIG. It incorporates what is memorized into the shape.

This actuator is stable and stationary at room temperature in the state shown in FIG. In this state, when the planar heating element (5) is heated by electricity, the shape memory alloy plate (1) is heated and returns to the memorized original shape and is reversed, as indicated by the dotted line (B).
) to the right as shown.

At this time, the shape memory alloy plate (2) jumps and reverses as shown by the dotted line (B'), buckling in the opposite direction to the memorized shape, and the shaft (4) moves to the right and remains stable in this state. . Next, when the planar heating element (5') is heated by electricity, the shape memory alloy plate (2) is heated and returns to the memorized shape and is reversed, and the shaft moves to the left and comes to a stable standstill. In this way, when the sheet heating elements (5) and (5') are alternately energized, the shape memory alloy plates are heated alternately, and the shape memory alloy plates are reversed to move the shaft and drive it intermittently or continuously. It is possible to do so.

! In the above, an example was explained in which the shape memory alloy plate (1) is reversed from the memorized shape and combined, but the alloy plate to be reversed may be either (1) or (2), and the initial heating is reversed. When applied to an alloy plate, that alloy plate returns to its original shape, and the force causes another alloy plate to flip over and buckle, and then by alternately heating it, drive in two directions can be obtained. be.

〔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. It can maintain its position even if Furthermore, two necessary positions can be selected and maintained without heating. Furthermore, since a planar heating element is used for heating, heating conditions are easy to set, and it is compact and inexpensive, and has many other remarkable effects.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the operating state of the actuator of the present invention, and Fig. 2 is a diagram showing an embodiment of the present invention.
3 is a vertical cross-sectional view seen from the front, (b) is a vertical cross-sectional view seen from the side, and FIG. 3 is a diagram showing a conventional actuator. 1...Shape memory alloy plates combined inverted, 2...
Shape memory alloy plate, 3... Stopper, 4... Shaft, 5, 5'... Planar heating element, 6, 6'...
・Fixing tool, 7, 7'... Insulator, 8, 8'...
Terminal, 9/9'...Insulator, 10/10'...Case, 11...Volt, 12...Coil spring.

Claims (1)

[Claims] A plurality of shape memory alloy plates are memorized in an arcuate or conical shape, and one or more of the shape memory alloy plates is inverted symmetrically with the memorized shape and combined in parallel with the shaft, and the shape memory alloy plates are An actuator characterized in that a sheet heating element is provided on the surface, and the sheet heating element is energized to alternately heat and reverse the shape memory alloy plate to drive the shaft in two directions.