JPS60257385A - Temperature actuating element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature-operated element using a shape memory alloy spring used in various sensors, actuators, and the like.

[Conventional technology]

Shape memory alloy is a constant temperature (martensitic transformation point)
The property of memorizing a shape at a higher temperature (hereinafter abbreviated as high temperature), and even if it is deformed at a temperature lower than a certain temperature (hereinafter abbreviated as low temperature), it will recover to the memorized shape simply by heating to a high temperature. including Ni-Ti alloys,
Cu-Zn-Af alloys, Au-cd alloys, and the like are known. This type of shape memory phenomenon is normally an irreversible phenomenon; when an alloy is deformed at a low temperature and then heated to a high temperature, it returns to the memorized shape, but even if it is cooled to a low temperature again, the shape that was deformed at a low temperature will not be retained. Dont return.

In order to utilize such characteristics industrially, it is desirable to operate reversibly and repeatedly, and various methods have been proposed for this purpose, one of which is known as a bias method. This method takes advantage of the properties of shape memory alloys, which are soft at low temperatures and have low yield stress, hard at high temperatures where they recover their shape, and have high yield stress, and deformation at low humidity is performed using an appropriate external force (paisuka). This structure has advantages such as a high degree of freedom in design and the use of a small amount of shape memory alloy, and is widely used in temperature-activated devices and the like.

Various types of temperature-activated elements using the bias method are known, but generally, as shown in Fig. 3, a bias spring (1) made of a shape memory alloy spring (1) and a normal spring material is used.
2), the load (3) is placed so as to give an appropriate deflection and pull the load (3) against each other. Since the shape memory alloy spring (1) of this actuating element is soft at low temperatures, the bias spring (2)
The load (3) is pulled by the elastic force of the bias spring (
2) side (right side in the figure).

When the temperature rises to a high temperature, the shape memory alloy spring (1) recovers its shape and at the same time becomes harder and stronger than the bias spring (2), and the load (3) is pulled by the shape memory alloy spring (1) and the shape memory alloy Move to the spring (1) side (left side in the figure). When the temperature drops to a low temperature, the load (3) is pulled by the bias spring (2) and moves toward the bias spring (2) again, and this operation is repeated reversibly in response to changes in temperature.

[Problem that the invention seeks to solve]

However, the temperature-activated element described above has a structure in which a shape memory alloy spring and a bias spring are simply stretched together. As the deflection of the spring decreases, the tensile force gradually decreases, and conversely, the elastic force of the bias spring gradually increases as it is stretched and stretched.
The force applied to the load, that is, the difference in force between the shape memory alloy spring and the bias spring will rapidly decrease as the shape memory alloy spring recovers its shape. This is exactly the same when the temperature drops to a low temperature and the shape memory alloy spring is pulled by the elastic force of the bias spring to transfer the load. If an attempt is made to widen the operating range (stroke) of the element and increase the force applied to the load, the entire element becomes large, which not only makes it difficult to downsize the device, but also causes an increase in cost.

[Means for solving problems]

In view of this, as a result of various tests, the present invention has a larger operating range and generated force than conventional ones by using a constant force spring whose load does not depend on deflection for either or both of a shape memory alloy spring and a bias spring. A temperature-operated element is obtained, in which a shape-memory alloy spring that recovers its shape depending on temperature and a bias spring are combined, and the actuator is operated reversibly by changes in temperature.
This is characterized in that either or both of the ear springs are constant force springs.

That is, in the present invention, a shape memory alloy spring and a bias spring are given appropriate deflection and arranged so that the load is pulled against each other, and at low temperatures the elastic force of the bias spring is used to pull the load and move it to the bias spring side, and at high temperatures the shape is In an actuating element that pulls a load and moves it toward the shape memory alloy spring by restoring the shape of the memory alloy spring, either or both of the shape memory alloy spring and the bias spring are fixed load springs.

A constant force spring is a special spring in which the elastic force of the spring hardly changes with the amount of deflection of the spring. Which spring to use or which spring to use may be determined depending on the use of the actuating element, its purpose, etc.

[For production]

When a constant force spring is used as a bias spring, when the shape memory alloy spring contracts due to shape recovery when the temperature changes from low temperature to high temperature,
The tensile force of the spring gradually decreases as it contracts, but the tensile force of a constant force spring does not increase as the spring stretches, greatly improving the loading force and range of motion. Further, a similar improvement can be obtained by using a constant force spring for the shape memory alloy spring, and an even further improvement can be obtained by using a constant force spring for the bias spring and the shape memory alloy spring. In particular, using a constant force spring as the bias spring facilitates the design of the actuating element.

〔Example〕

As shown in Figure 1, Ni-'Fi shape memory alloy (
1) and a spiral-shaped constant force spring (4) made of ordinary spring material.
) as a bias spring, give an appropriate deflection and load (
3) were arranged so as to be pulled together to form an actuating element of the present invention. Regarding this, the operating state was calculated by taking the elastic forces and deflection curves of each spring (1) and (4) under -U(fi temperature) and the high temperature, and compared to the case of the conventional actuating element shown in Fig. 3. A comparison is shown in FIG.

Figure 2 shows the elastic force and deflection curve of each spring, with the vertical axis representing the elastic force of the spring and the horizontal axis representing the amount of spring deflection. The elastic force and deflection curves of the shape memory alloy spring at high temperature, (2) the bias spring of the conventional element, and (4) the bias spring consisting of the constant force spring of the present invention element are shown. The points where the elastic forces are balanced at high temperatures are points A and B in conventional elements, and the operating range under no load is between AB (approximately e
mm), whereas the operating range of the device of the present invention is between CDs (approximately 23 M), which is more than twice the operating range of the conventional device.

〔Effect of the invention〕

According to the present invention, the operating range and generated force of the temperature-operated element can be greatly improved [1], and it can be used in sensors, actuators, etc., and can be made lighter and smaller, which is industrially significant. It is something that reduces the effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the actuating element of the present invention, and FIG.
The figures are elastic force and deflection curves of each spring in the actuating element of the present invention and the conventional actuating element, and FIG. 3 is an explanatory diagram showing an example of the conventional actuating element. 1... Shape memory alloy spring 2... Bias spring 3... Load 4... Constant force spring

Claims (1)

[Claims] In an actuating element that combines a shape memory alloy spring that recovers its shape depending on temperature and a bias spring, and operates reversibly according to temperature changes, either or both of the shape memory alloy spring and the bias spring are fixed force springs. A temperature-activated element characterized by: