JPS60219476A - Actuator - Google Patents

Abstract

PURPOSE:To obtain an actuator which performs complicate movement by making partially different the shape recovery time of a shape memory alloy material. CONSTITUTION:The diameter of a shape memory alloy wire 1 is made different. The electric resistance is made partially different because of the difference of diameter. The part having the thinner diameter earlier reaches the shape recovery temperature through conduction heating. Different shape recovery time can be obtained by forming a conductive layer 2 having the equal resistance to that of the wire 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an actuator, and particularly to an actuator using a shape memory alloy.

[Technical background of the invention and its problems]

Conventionally, actuators using hydraulic pressure, pneumatic pressure, motors, etc. have been widely used. In addition, recently 'I'1-Ni alloy, Cu-Zn alloy, Cu-A
Attempts have been made to use shape memory alloys such as L alloys as actuators. Actuators using these shape memory alloys are lightweight and can achieve much higher output per unit weight than conventional actuators, but on the other hand, they mainly perform relatively simple movements such as reciprocating motion. For example, actuators for opening and closing windows, temperature switches, etc.

On the other hand, if it is equipped with arms, joints, pulleys, etc., it is possible to make complex movements similar to those of a robot hand, but it has disadvantages such as the complexity of the structure and the overall weight of the system.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and an object of the present invention is to provide an actuator using a shape memory alloy that has a simple structure and can perform complex movements.

[Summary of the invention]

The present invention provides an actuator in which a shape memory alloy element is driven multiple times by electrically heating the actuator, characterized in that the shape memory alloy element is configured such that shape recovery timings are partially different from each other. be.

The concept of driving a shape memory alloy element by electrical heating is known. The present invention is an actuator that is capable of performing complex movements by heating with electricity by partially varying the shape recovery timing of the element body.

Shape memory alloys include Ti-Ni alloy, Cu-Zn
Various commonly known alloys such as alloy and Cu-k1 alloy can be used.

As a means for partially varying the shape recovery timing, there is a method of applying two currents.

(1) Partially changing the shape recovery temperature.

(2) Partially slowing down the temperature rise.

When using the method (I), the shape recovery time can be changed by, for example, partially shifting the alloy composition. For example, Ti-Ni alloy has a Ti content of 49 to 51a.
The shape recovery temperature can be changed from 100 to 100° C. by changing t%. Therefore, assuming that the temperature rises uniformly during electrical heating, if shape recovery occurs from the lowest point at the shape recovery temperature, then K. Such a shape memory alloy can be obtained, for example, by coating a Ti wire with Ni and diffusing it to varying degrees.

When using the method (2), for example, it is conceivable to partially change the electrical resistance value. It is also possible to partially change the resistance value by adding a dopant. Furthermore, if the wire diameter is made thinner in a portion, the resistance value of that portion increases, so when heating with electricity, it is similar to a series resistance, so the portion where the wire diameter is thinner generates the most heat. Therefore,
The thinner diameter portion of the wire reaches the shape recovery temperature the fastest, and shape recovery occurs. It is also conceivable to apply a conductive coating such as Cu plating and change the film thickness.

Such an actuator of the present invention can produce displacement partially at different times. Therefore, by continuously changing the timing of shape recovery in the longitudinal direction of the wire, the displacement can be made to progress. For example, if the waveform is stored, a traveling wave can be formed, and a self-propelled actuator can be constructed.

Although it depends on the degree of heating, shape memory alloys recover their multiple shapes when heated with electricity, and return to their original shapes when heating is stopped. Generally, it takes time for return to return, so it is also possible to speed up return by twisting multiple shape memory alloy wires together, selectively heating them, and using the unheated wires as spring material.

Alternatively, it may be used simply in combination with a spring material such as phosphor bronze.

Furthermore, the recovery speed can also be increased by covering with insulating rubber such as silicone rubber.

〔Effect of the invention〕

As explained above, according to the present invention, complex movements can be produced with a simple configuration. An actuator using a shape memory alloy can be obtained.

[Embodiments of the invention]

The present invention will be explained in detail below.

First, shape memory alloy wires (1) with partially different shape recovery times are prepared. As mentioned above, there are several methods, but for example, as shown in Figure 1 (as shown as a cross-sectional view)
There is a method of varying the diameter of the wire (1). Electrical resistance is inversely proportional to the cross-sectional area, so when heating with electricity, the smaller the cross-sectional area, that is, the smaller the diameter, the greater the amount of heat generated.If the wire (1) is made of the same composition, the smaller the diameter. When the shape recovery temperature is reached first, it becomes K. Also, the first
As shown in Figure (b), a conductive layer (2) is formed on the surface of the wire (1) by plating or the like, and the thickness of the conductive layer (2) is changed to change the current flowing through the wire (1). can. At this time, it is meaningless if no current flows through the wire (1), so it is preferable to use a material having a resistivity similar to that of the wire (1) as the conductive layer (2).

All of the devices shown in FIG. 1 are constructed so that the shape recovery time is delayed from the cloth to the left in the figure.

Next, as shown in FIG. 2, the actuator (4) is constructed by combining the wires (1) II)' with two wires that maintain electrical insulation. At this time, the entire body may be covered with an elastic body (3) such as silicone rubber. Movement is smoother when covered. The wires (1) and (1)' can each be heated with electricity.One wire (1) is heated with electricity to recover its shape, and then the heating is stopped and the other wire (IY is a spring material) is heated. Wire (1)
to restore its shape. Shape memory alloys vary depending on the degree of heating.
Since it is possible to return without a spring material, it is not necessary to make a pair, but when the return speed is taken into account, it is preferable to use a combination of spring materials. Moreover, instead of the wire (barb), a spring material such as phosphor bronze may be used. Also, the above-mentioned elastic body (3) also has a restoring force.

However, if both wires CI) (1)' are made of a shape memory alloy, more complex movements are possible.

Next, FIG. 3 shows an example of the movement of the actuator of this embodiment. The specially constructed actuator (4
) have their shapes memorized so that each wire (1) (1γ (not shown in FIG. 3) has a waveform as shown in FIG. 3(C) in a high temperature state. Assume that the wire is configured so that its shape changes and returns sequentially from the right side to the left side in the figure.Then, due to electrical heating, the shape recovery occurs sequentially from the right side, and due to friction, the left side is pulled toward the right side. K (Fig. 3 (b)). In the figure, G indicates the position of the center of gravity, but when the overall shape recovery occurs, the position of the center of gravity shifts to the right by δ from the initial position (Fig. 3 (C)
)).

Next, when the current heating is stopped, the actuator (4) returns to the shape of the low temperature state due to the restoring force of the wire that has not been heated, and as a result moves in the direction of the arrow (A) in the figure (ψ) in the figure. A displacement of δ can be obtained.

Here, for example, if the other wire that was not heated by electricity when the movement in Figure 3 occurs is configured so that it recovers its shape from left to right in the figure, it will be similar to the arrow (A).
Movement in both directions is possible.

In this way, in this embodiment, a self-propelled actuator can be obtained, which is particularly effective for use in narrow spaces and in bad environments. Furthermore, although the above-mentioned embodiments are self-propelled, it is also possible to form standing waves, for example, and it is possible to obtain actuators that produce various movements depending on the desired application.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a shape memory alloy wire obtained according to the present invention;
FIG. 2 is a sectional view of the actuator according to the present invention, and FIG. 3 is a conceptual plan view showing the operation of the actuator according to the present invention. Agent: Patent attorney Noriyuki Chika (and 1 other person) Figure 1

Claims (3)

[Claims] (1) An actuator in which a shape memory alloy element body is driven by electrical heating, wherein the shape memory alloy element body is configured so that shape recovery timings are partially different from each other. (2) The actuator according to claim 1, wherein the shape memory alloy element body has partially different shape recovery temperatures. (3) The actuator according to claim 1, wherein the shape memory alloy element body has partially different electric resistances.