JPS63215882A - Actuator - Google Patents

Abstract

PURPOSE:To secure such an actuator that is longer in service life and makes the form of a form memory alloyed plate reverse and then reciprocate a shaft, by alternately heating each of plural shape memory alloyed plates stored into a semielliptic or conical form having a flat part on the top. CONSTITUTION:A strip plate of a shape memory alloy is stored into a semielliptic form having a flat part L on the top, and this plate 1 is reversed at room temperature, setting it down to the shape memory plate 1. This reversed shape memory plate 1 and an original shape memory plate 2 are pierced through a shaft 4 together with a stopper 3. Forming an actuator, and each upper and lower end of these shape memory plates 1 and 2 is fixed there. And, the shape memory plate 1 being in a (b) state at the room temperature is heated whereby this plate 1 is restored to the memory form, and simultaneously the shape memory plate 2 is buckled and reversed. Next, the shape memory plate 2 is heated in a (c) state, whereby both these shape memory plates 1 and 2 rotated in the reverse direction, and the shaft 4 is driven by suchlike actuation.

Description

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

(Prior Art and its Problems) Various actuators using shape memory effects such as Ni-Ti alloys are known. These poly(things) have high properties when the shape memory alloy itself has two-way properties.
Since the shape of each low temperature side cannot be set accurately,
It utilizes a shape memory alloy with unidirectional properties. 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.

Namely, shape memory alloy coil (5) and coil spring (6)
are arranged in parallel to the central axis (8) via a stopper (7).When the temperature is low, the shape memory coil is in a contracted shape due to the coil spring's piascus, but when the shape memory coil is heated, it can be heated to a high temperature. When this happens, they move towards the carp. 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 central axis to the left.

By repeating such operations, driving forces in two directions are applied to the central shaft. In addition, the differential type uses a shape memory coil instead of the coil spring (6) in Figure 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. 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. 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, 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.

The present inventor studied the above problems, made this improvement, and “
A patent application was filed on January 31, 1986 for the title "actuator". As shown in Fig. 2, this invention allows a rectangular plate of shape memory alloy to memorize the shape of a rectangular shape as shown in Fig. 2 [al]. One sheet has an inverted shape, and the other has a bow-shaped shape memory (
2) in parallel with the shaft (4) via the stopper (3).
), the upper and lower ends of the shape memory alloy plates are fixed, and each shape memory alloy plate can be heated alternately. When the shape memory alloy plate (1) is heated to a predetermined temperature when it is stable at low temperatures in this state, the second
As shown in Figure (cl), the shape memory alloy plate fi+ returns to its original memorized shape. At this time, the shape memory alloy plate (2) also
From the memorized shape of l (like cl, it jumps, buckles, and reverses, and the shaft (4) is driven to the right, stops heating, and remains stable in this state even when it is cooled.Next, when in this state When the shape memory alloy plate (2) is heated, the shape shown in Fig. 1 (bl
At No. 5, the shape memory alloy plate (2) returns to its original memorized shape, and the shape memory alloy plate (11) also jumps, buckles and reverses, and the shaft (4) is driven to the left. By repeating the above operations, it is possible to provide intermittent or continuous drive to the shaft in two directions.

That is, since it is a combination in which at least one of the shape memory alloy plates is reversed from the memorized shape, it jumps and reverses during operation and becomes a buckled state, so that a stable stationary state can be maintained even during cooling.

(Problems to be Solved by the Invention) Although the above invention achieved the intended purpose, it was found that another problem arose. That is, when viewed microscopically, at low temperatures, the arc appears to be collapsed by a length b) according to the stress distribution, as shown by the dotted line in FIG. 3, and the displacement decreases by that amount. This causes some play in the actuator itself, resulting in backlash.

To prevent this, it is extremely difficult to memorize a shape that corresponds to the stress distribution at low temperatures due to changes in plate thickness, heat treatment errors, etc. In order to prevent the above-mentioned backlash, it is necessary to apply a stopper to the shaft further before the position shown by the dotted line, but this causes large distortion to the alloy plate, causing fatigue to the alloy plate and reducing the number of operations.
In other words, it has been found that this causes a decrease in the repeat life.

The present invention is an actuator that prevents backlash and has a long life as a result of studying the above-mentioned problems.

(Means and effects for solving the problems) The present invention stores a plurality of shape memory alloy plates in an arcuate or conical shape having a flat portion at the top, and one or more of these shape memory alloy plates is memorized. The shape memory alloy plate is reversed symmetrically with the shape and combined in parallel with the shaft, and the reversed shape memory alloy plate is returned to the memorized shape by heating, and the other shape memory alloy plate is reversed to drive the shaft in two directions. This actuator is characterized by:

That is, in the present invention, as shown in FIG. 1, a rectangular plate of a shape memory alloy made of Ni-Ti or the like is memorized into an arcuate shape having a flat portion at the top, as shown in FIG. 1(a). One of these sheets is inverted to be symmetrical to the memorized shape at room temperature as shown in (1) in FIG. ) is inserted into the shaft (4).

The upper and lower ends of the shape memory alloy plates (1) and (2) are fixed, and each can be heated separately.
The actuator is thermally insulated. To explain this operation, when shape memory alloy plates (1) and (2) are stable at low temperatures in the state shown in Figure 1 (bl), when shape memory alloy plate (1) is heated to a predetermined temperature, Figure 1 (c ), the shape memory alloy plate (2) returns to its original memorized shape. At this time, the shape memory alloy plate (2)
Even if the shaft (4) is driven to the right, stops heating, and is cooled, it remains stable and stationary in this state. Next, in this state, when the shape memory alloy plate (2) is heated with electricity, the shape memory alloy plate (2) returns to its original memorized shape as shown in Fig. The shaft (4) moves and buckles and reverses, driving to the left and stably stationary in this state.By repeating the above operation, it is possible to give the shaft intermittent or continuous driving in two directions. becomes.

Therefore, in the present invention, at least one of the shape memory alloy plates is inverted from the memorized shape and combined, and this jumps and inverts during operation, resulting in a buckled state, so that a stable stationary state can be maintained during cooling.

In addition, in the present invention, since the shape memory alloy plate is memorized in an arcuate or conical shape with a flat part at the top, it retains the shape of the solid line at high temperatures, but at low temperatures, as shown in Figure 1 (al). The distributed stress results in a shape approximately shown by the dotted line, that is, the displacement of the actuator increases by the length a.

However, if this actuator is constructed so that the moving point of the shaft can only move up to the position of the memorized shape, the stress generated by the strain a acts on the shaft as back pressure.

Therefore, it is possible to manufacture an actuator without backlash. Also, when it is reversed, it acts as a turning point.

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 alloy, shape memory alloys include Fe.
, Ni-Ti alloys containing a third element such as Go, and Cu alloys such as Cu-AJ-Ni and Cu-Au-Zn.
In addition to these alloys, commonly used shape memory alloys can be used.

Furthermore, as heating methods for shape memory alloys, in addition to electrical heating,
Conventional heating methods such as hot air and gas flames can be used.

(Example) An embodiment of the present invention will be described below.

As shown in FIG. 1(a), a rectangular plate made of a Ni--Ti alloy was shaped into an arcuate shape having a flat portion (Ll) at the top thereof, and was then subjected to shape memory heat treatment.

Next, this plate was inverted at room temperature and the same figure (bl (1)
As shown in Figure 1, the shaft (4) was passed through the stopper (31) together with the alloy plate (2) in its memorized shape to form an actuator.The shape memory alloy plate (1),
(2) can be heated separately by electricity or gas flame heating. The above-mentioned actuator is stable and stationary in the state shown in Fig. 1 (in the state bl) at room temperature, but when the shape memory alloy plate 11 is heated, it rolls and buckles, and the shaft (4) is driven to the right. Even if the heating is stopped and the product 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 its original memorized shape as shown in the same figure (b), and the shape memory alloy plate (1) also flies away. The shaft 4) is moved and reversed and buckled, and is driven to the left and remains stable in this state. By repeating the above operations, it is possible to drive the shaft intermittently or continuously.

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 (11 or (2)), and the initial heating is reversed. When applied to an alloy, the alloy returns to its original shape, and the force causes another alloy to go into an inverted buckled state, and then by alternately heating it, drive in two directions can be obtained.

(Effects) 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, giving reciprocating motion in two directions, and at the same time heating can be performed. can be stopped and maintain its position even in low temperatures. In addition, it can select and maintain two required positions, has no backlash, has high operating precision (and has a long repeat life, etc.), and has extremely significant effects.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the operating state of the actuator of the present invention, Fig. 2 is a schematic diagram showing the operating state of the actuator of the prior art, Fig. 3 is a schematic diagram showing the operating state of the actuator of the prior art, and Fig. 4 is a schematic diagram showing the operating state of the actuator of the prior art. The figure is a schematic diagram showing the operating state of a conventional actuator. DESCRIPTION OF SYMBOLS 1... Shape memory alloy plate which was reversed and combined, 2... Shape memory alloy plate, 3... Stopper, 4... Shaft, 5... Shape memory coil, 6... Coil spring, 7.
... Stopper, 8... Central axis. Patent applicant Furukawa Electric Co., Ltd. (a) (b) (c
)Figure I (a) (b) (C)Figure 2Figure 4

Claims (1)

[Claims] A plurality of shape memory alloy plates are memorized into an arcuate or conical shape having a flat portion at the top, one or more of the shape memory alloy plates are inverted symmetrically with the memorized shape and combined in parallel on a shaft, An actuator characterized in that a shape memory alloy plate that has been inverted by heating is returned to its memorized shape, and the other shape memory alloy plate is inverted to drive a shaft in two directions.