JPS6185079A - Actuator - Google Patents

Abstract

PURPOSE:To increase the available range by providing a conductive layer divided into a plurality on the surface of a shape memory cell, and independently supplying currents thereto, thereby increasing the output. CONSTITUTION:An actuator 10 is composed of a supporting mechanism 11, a shape memory cell 12 secured to the mechanism, 1 transmitting mechanism 13 for transmitting the opening regulator of a valve Z for the mechanical displacement of the movable end side of the cell, and a current supply unit 14 for heating the cell 12 by Joule heat. After the element 12 is linearly stored in the shape, it has a strip alloy plate 24 formed in an arcuate shape. In this case, conductive layers 25-27 are coated longitudinally at three positions on one surface of the plate 24, conductive layers 28, 29 are coated on both end faces, and the layers 25-29 are energized from the unit 14. Thus, one zone partitioned by the layers 25-29 is selectively energized to partly recover the shape in the cell 12, thereby stepwisely controlling finely the operation amount.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an actuator that obtains an operating state by utilizing the shape memory effect of a shape memory element, and particularly relates to an actuator in which the shape memory element is formed of a shape memory alloy, and The present invention relates to a type of actuator that controls shape recovery of a shape memory element using Joule heat generated by a current supplied to the shape memory element itself.

[Technical background of the invention and its problems]

As is well known, Ni-7i alloys and Cu alloys whose composition ratios are appropriately set have a shape memory function.

Such shape memory alloys have the unique property of recovering their memorized shape when heated to a predetermined temperature. This unique property can be effectively utilized in things that require mechanical displacement, such as various actuators and switches.

By the way, in order to cause a shape memory element formed of a shape memory alloy to perform a shape recovery operation, heat is applied to the shape memory element by some means, and the temperature is raised to a temperature higher than the reverse transformation point required to return to the memorized shape. In other words, it is necessary to raise the temperature to a temperature that can eliminate martensite. There are various ways to raise the temperature in this way, but an actuator that incorporates this type of shape memory element (well, in general, when current is passed through the shape memory element itself, A method of raising the temperature using Joule heat is adopted.

This so-called energization heating method allows shape recovery control to be performed by energization without 1<), which contributes to the simplification of the control system compared to other methods.

In conventional actuators equipped with a shape memory element made of a shape memory alloy, electrodes are usually provided at both ends of the shape memory element. Then, during shape recovery control, a current is passed through these electrodes to the entire shape memory element to perform Joule heating. At this time, the current flowing through the shape memory element flows almost uniformly throughout the shape memory element.

Therefore, Joule heat is also generated uniformly over the entire shape memory element, and shape recovery caused by this heat also occurs uniformly over the entire shape memory element. In this way, in conventional actuators of this type, the temperature of the entire shape memory element is raised to a temperature exceeding the reverse transformation point temperature, and the entire shape memory element is instantly displaced to the memorized shape. A method that uses displacement is adopted.

However, as mentioned above, conventional actuators that utilize only stepwise displacement of the entire shape memory element can only perform one simple operation.
The disadvantage is that the usable range is significantly narrower. For example, a human finger-like grip with one actuator
It cannot be made to perform any action or to perform multiple types of complex actions. For this reason, there was a problem in that the range of use was inevitably specified.

In addition, in this type of actuator, it is desired to increase the payload as the use of the actuator expands, and for this reason, there is a desire for an actuator with a large output. The output can be increased by increasing the cross-sectional area of the shape memory alloy member used in the actuator, or by increasing the total cross-sectional area by using a plurality of shape memory alloy members. However, when a plurality of shape memory alloy materials are used, there are problems such as differences in shape recovery of each shape memory alloy member and complicated shape recovery control of each shape memory alloy member. Therefore, to increase the output power of the actuator, it is advantageous to increase the cross-sectional area of a small number of shape memory alloy members, preferably one shape memory alloy member. However, increasing the cross-sectional area of the shape memory alloy member reduces the total resistance of the shape memory alloy member, thus requiring a significant increase in current to raise the temperature to the required Joule heating. For this reason, a high-voltage, large-current, or large-capacity electrical heating power source is required, making it difficult to make the entire device compact.

[Purpose of the invention]

This invention was made in view of these circumstances,
The purpose of this is to increase the output while suppressing the increase in the capacity of the power source for energizing heating, and also to enable the desired complex operation, greatly expanding the range of use. The objective is to provide an actuator that can be expanded to

[Summary of the invention]

This invention includes a shape memory element formed of a shape memory alloy member that recovers its memorized shape when heated to a predetermined temperature, and shape recovery control of this element is generated by electric current supplied to the element itself. The target is actuators that operate using Joule heat.

In such an actuator, in the present invention, a conductive layer is provided over a plurality of locations on the surface of the shape memory element to partition the shape memory element into a plurality of sections, and these conductive layers are used as electrodes to independently divide the shape memory element into each section. A current supply device is provided to supply 1i current to the current.

〔Effect of the invention〕

According to the actuator of the present invention, one actuator can perform a desired complex operation.

That is, by using the above-mentioned conductive layer as an electrode and passing current through only a desired section of the shape memory element or sequentially to each section, shape recovery operation can be performed independently for each section. Therefore, one shape memory element can perform a plurality of types of complicated operations compared to the conventional one. Therefore, the range of use can be greatly expanded, such as being able to be applied to objects that require -M"am movements, such as the fingers of robots.

Further, according to the actuator of the present invention, it is possible to increase the output without increasing the capacity of the power supply for energization heating.

In other words, since a conductive layer is provided in the above relationship, a single electrical heating power source can be used to alternately supply current to, for example, two specified sections in time series, thereby restoring the shape of these two sections. You can also do it.

In this case, the electrical heating power supply only needs to be provided for the customer group that can flow the required current in one section. Therefore, even if the cross-sectional area of the shape memory alloy member constituting the shape memory element is increased in order to increase the output of the actuator, there is no need to correspondingly increase the capacity of the power source for energization. do not have. For this reason, it is possible to achieve a large output while at the same time making the entire device more compact.

[Embodiments of the invention]

FIG. 1 shows an example in which the opening degree of a valve 2 is controlled by an actuator 10 according to an embodiment of the present invention.

The actuator 10 includes a support mechanism 11 , a shape memory element 12 fixed to the support mechanism 11 in a cantilevered manner, and a mechanical displacement of the free end side of the shape memory element 12 that is transmitted to the opening adjustment section of the valve 2 . and a current supply device [14] that selectively supplies current necessary for Joule heating of the shape memory element 12 to the shape memory element 12.

The support mechanism 11 has one end side of a metal fitting 22 formed in an L-shape fixed to a support member 21 which is fixed to a member (not shown) by an appropriate means, and a relatively thick insulating metal fitting 22 on the other end side of the metal fitting 22. A base 23 formed of a plate is fixed.

The shape memory element 12 has a thickness of 0.5 mm and a width of 3 mm, for example.
M, length 60# Ni (50at%)-Ti (5
A band-shaped alloy plate 24 formed of an alloy plate (0at%), which is formed by shape memory treatment in a straight line as shown by x1 in the figure, and then deformed into an arc shape with a radius of curvature of 40 m, and this alloy plate 2.
It is composed of conductive layers 25, 26, and 27 deposited over three locations in the longitudinal direction on one surface of the alloy plate 24, and conductive layers 28 and 29 deposited on both ends of the alloy plate 24, respectively. .

The conductive layers 25, 26, 27, 28, and 29 are each composed of an electroplated copper layer having a thickness of 20 [μTrL]. The width of the conductive layer 25, 26, 27 along the longitudinal direction of the alloy plate 24 is set to 2111II+. The shape memory element 12 configured as described above has a conductive layer 29
The side where the conductive layer 28 is provided is the free end, and the side where the conductive layer 28 is provided is the base end, and the free end is located on the right side of the base 23 in the figure, and the free end is located at a distance from the base end with respect to the right side. They are arranged facing each other in a spaced apart relationship, and in this state, the proximal end side is fastened to the base 23 with a bolt 30. That is, a hole 31 is provided in the center of the portion of the alloy plate 24 covered with the conductive layer 28 so as to integrally penetrate the conductive layer 28, and a perforated conductive plate 32 is provided coaxially with the hole 31. , Apply the perforated spacer 33 to the surface of the conductive layer 28 located on the base 23 side of the above type, and insert the bolts 30 integrally into the hole 31, the perforated conductive plate 32, and the eight holes of the perforated spacer 33,
The tip of this bolt 30 is inserted into the hole 3 provided in the base 23.
4 and the tightening is fixed. The conductive plate 32 and the conductive layer 25, 26, 27, 29 are provided with flexible lead wires 35, 36, 37, 3, respectively.
8. One end side of 39 is soldered, and the other end side of these lead wires 35 to 39 is connected to the terminal 4 fixed to the support member 21.
0.41.42.43.44.

A through hole 45 is provided at a position of the base 23 facing the free end of the alloy plate 24, and a guide tube 46 is inserted and fixed into this through hole 45.

The transmission mechanism 13 is supported by the guide cylinder 46. The transmission mechanism 13 is inserted into the guide tube 46 so as to slidably pass through the guide tube 46,
A rod 47 made of an insulating material whose one end is in contact with the free end of the alloy plate 24 and whose other end is connected to the opening adjustment part of the valve 2 is connected between the base 23 of the rod 47 and the valve 2. A flange 48 protrudes from the outer periphery of the position, and a bias coil spring 49 that is inserted between the flange 48 and the valve Z and always applies a force to the rod 47 in the right direction in the figure. It is configured.

On the other hand, one end side of another lead wire 50.51.52.53.54 is connected to the terminals 40.41, 42.43.44, and the other end side of these lead wires is connected to the current supply device 14. It is connected.

The current supply device 14 is specifically configured as shown in FIG. That is, this current supply device 14 is
A DC N source 60 is provided, and the positive terminal of this DC power source 60 is connected to a semiconductor switch 61 composed of a transistor, a thyristor, etc.
~65 are connected in common to one end of each of them. The other ends of these semiconductor switches 61-65 are connected to the lead wires 50-54, respectively. These lead wires 50 to 54 are connected to one end of separate lead wires 71 to 75, respectively, and the other ends of these leads 171 to 75 are connected to semiconductor switches 81 to 85, which are also made of transistors, thyristors, etc. Each is connected to one end. The other ends of the semiconductor switches 81 to 85 are commonly connected to the negative electrode of the DC power supply 60. The semiconductor switches 61 to 65 and 81 to 85 are turned ON and 0FFIIJ@ by the switch controller 90. This inch controller 90 receives control signals 81 to S4 from a control system (not shown).
When this control signal is given, each semiconductor switch is turned ON so that a current flows through the section of the alloy plate 24 designated by this control signal. Specifically, it is configured to perform ON/OFF control as follows. That is, if a control signal designating the section A1B located between the conductive layer 29 and the conductive layer 26 of the alloy plate 24 is given, first the semiconductor switches 61 and 82 are turned off for a short period T.
A current is caused to flow through section iiA located between the conductive layer 29 and the conductive layer 27 by controlling the current to be in the N state. Subsequently, at the end of the above period, the semiconductor switches 61 and 82 are turned OFF #JIII, and the semiconductor switch 62.83 is controlled to be ON for a period T to be located between the conductive layer 2.7 and the conductive layer 26. A current is applied to section B. Next, the semiconductor switch 6 is turned on again.
1.82 is controlled to be ON for a period T to flow a current through the section 11flA located between the conductive layer 29 and the conductive layer 27. Thereafter, the above-described energization control is repeated. That is, in any case, each semiconductor switch is controlled to be ON so that current flows only in one section defined by the conductive layer, thereby restoring the shape of the designated section of the alloy plate 24. FIG. 3 shows the time relationship of the current flowing in each section when all sections A, 81C, and D are specified.

With such a configuration, the shape memory element 12 can be partially restored in shape by providing the conductive layers 25 to 29 so as to partition the shape memory element 12 into a plurality of sections in the longitudinal direction. , the amount of operation can be controlled finely and in multiple types in a stepwise manner. Further, since the conductive layers 25 to 29 are provided in the above-mentioned relationship, it is possible to adopt a method in which current is always passed only in one section, which is the minimum unit divided by the conductive layers, as in the embodiment. Therefore, even if the cross-sectional area of the alloy plate 24 is increased in order to increase the output, the DC power supply 60 only needs to be capable of supplying current to one section, and a large-capacity one is required. This not only makes it possible to use a lead wire with a small diameter, but also enables the use of lead wires with a small diameter, and as a result, the effects of the present invention described above can be achieved.

As can be seen from the operation of this embodiment, the conductive layers 25 to 29 provided on the surface of the alloy plate 24 are used as electrodes. Therefore, the material forming the conductive layer should preferably have high electrical conductivity, and in addition to copper, gold, silver, aluminum, nickel, or alloys thereof are preferable. In addition, by actively dissipating heat through the conductive layer, it is possible to suppress heat transfer between sections located on both sides of the conductive layer, and to perform highly accurate displacement control.

Therefore, as a constituent material of the conductive layer, a material having a higher thermal conductivity than a shape memory alloy is more preferable. Furthermore, by selecting the thickness or width of the conductive layer, it is possible to suppress recovery of the shape of the portion where the conductive layer is provided. Therefore, it is also possible to prevent the connection portion of the lead wire from coming off due to repeated stress.

Here, a basic experimental example related to this example will be disclosed.

Experimental example 1 N1 (at5
0%)-Ti (at50%) alloy wire with a diameter of 0°2M
Wm's first, second, and third copper wires are wound around the above type at intervals of 1.7α and mechanically joined, and then the radius of curvature between the wound portions of the above copper wires is 3ttm. A shape memory element that was uniformly deformed was obtained. A voltage of 0.3■ is applied to the section where these copper wires are connected through the first and second copper wires to the shape memory element configured in this way, and a current of 0.38A is caused to flow. Also, 0.5V is applied to the section where these copper wires are connected via the second and third copper wires.
A voltage of 0.5 A was applied and a current of 0.5 A was caused to flow. the result,
The section where 0.38A flowed completely recovered its shape in about 3.5 seconds, and the section where 0.5A flowed completely recovered its shape in about 1.5 seconds.

Experimental Example 2 In Experimental Example 1, the copper wire was wound with a width of approximately 2 mm and a thickness of approximately 2 mm on the surface of the alloy wire where the first, second, and third copper wires were connected in order to reduce the resistance. Copper plating layers of 30 [μm] in thickness were provided, and first, second, and third copper wires were soldered to these plating layers. Then, as in Experimental Example 1, the first
, a voltage of 0.3■ is applied between the second copper wire, and the second and third copper wires are
When a voltage of 0.5V was applied between the copper wires of -, 0.3
The section where V was applied recovered its shape in about 2.5 seconds, and the section where 0.5 V was applied recovered its shape in about 1 second.

Experimental Example 3 Using the shape memory element used in Experimental Example 1, a voltage of 1.3 V was applied only to the section where the first and second copper wires were connected, and a current was caused to flow. When examining the transfer of heat to the section to which the third copper wire was connected, it was found that the shape began to recover approximately 5 seconds after the start of energization, and the shape was completely recovered approximately 90 seconds later. When the applied voltage was set to 0.5V, the second and third
The section where the copper wire was connected did not recover its shape even after 180 seconds.

Experimental Example 4 Using the shape memory element used in Experimental Example 2, a voltage of 1.3cm was applied only to the section where the first and second copper wires were connected, and a current was applied to the second and second copper wires. When we investigated the transfer of heat to the section where the No. 3 copper wire is connected, we found that the section where the No. 2 and No. 3 copper wires are connected did not completely recover its shape even after 180 seconds had passed from the start of energization. There wasn't. Also, the applied voltage is 0.5V
As a result, the section where the second and third copper wires were connected did not recover its shape at all even after 180 seconds had passed since the start of energization.

Next, an actuator 10a according to a second embodiment of the invention will be described with reference to FIG. This actuator 10a is used as a device for grasping an object.

This actuator 10a is basically constructed in the same way as the actuator shown in FIG.

That is, the shape memory element 12a incorporated in this actuator 10a is made of Ni, similar to that shown in FIG.
(at50%)-Ti (at50%)'' alloy plate 100 formed into a band shape, and a copper plating layer deposited on one surface of the alloy plate 100 at equal intervals along the longitudinal direction. It is composed of conductive layers 101, 102, 103, and 104, and a similar conductive layer 105 deposited on both sides of one end of the alloy plate 100. The alloy plate 100 is subjected to shape memory treatment so that the portion opposite to the side on which the conductive layer 105 is provided has an arc shape, as shown by the two dotted chain lines in the figure, and then deformed into a straight line. has been done. Each conductive layer 101
The width in the longitudinal direction of the alloy plates 100 104 to 104 is set to, for example, 2M. The shape memory element 12a configured as described above is fixed in a cantilever manner to the base 108 with a bolt 107 with the portion where the conductive layer 105 is provided with the conductive plate 106 interposed therebetween. Note that the base 108 is selectively controlled to move in the vertical direction in the figure and in the direction orthogonal to the plane of the paper by a drive mechanism (not shown). The conductive plate 106 and the conductive layers 101 to 104 each have a lead I1111.11.
One end of 2.113, 114, and 115 is electrically connected, and the other end of these lead wires is connected to a current supply (not shown) configured as shown in FIG. 2 via connection terminals (not shown), respectively. connected to the device.

Next, a description will be given of the operation when the actuator 10a configured as described above is used to grasp a cylindrical object and convey this object to a desired location.

First, the base 108 is moved and the shape memory element 12a is
The position is set so that the surface on the side where the conductive layer is not provided is in contact with the outer peripheral surface of the object W. Subsequently, a current is passed through the section located between the conductive layer 101 and the conductive layer 102 to restore the shape of this section. When the shape is restored in this way,
As shown in FIG. 5(a), the section whose shape has been restored comes into close contact with a part of the outer peripheral surface of the object W. Subsequently, conductive layers 101 and 10
While current is flowing in the section between conductive layer 102 and conductive layer 103, current is further passed through the section between conductive layer 102 and conductive layer 103 to restore the shape of this part. When the shape is restored in this way, the shape memory element 12a becomes the object W as shown in FIG. 5(b).
It is in close contact with more than 1/2 of the outer circumference. Subsequently, the conductive layer 103
A current is also passed through the section located between and the conductive layer 104,
The shape of this section is restored. When this section is restored to its shape, the shape memory element 10a comes into close contact with more than two-thirds of the outer circumference of the object W, as shown in FIG. 5(C), and tightens the object W.

Therefore, by moving the base 108 in this state, the object can be transported to a desired location.

In this way, the actuator 10a according to this embodiment can grip an object by performing a motion similar to a human finger. Therefore, it can also be applied to manipulators.

In the two embodiments described above, the current supply device shown in FIG. 1 is used, but as shown in FIG. You may make it use the electric current supply apparatus 131 which has the power supplies 125-127 for energization heating corresponding one-to-one to each area set by 121-124. In addition, in the figure, 128 to 130 indicate switches. Furthermore, in each of the above embodiments, a shape memory element formed in a plate shape is used, but as can be seen from the description of these embodiments, the shape memory element may be shaped into a line, film, or rod depending on the application. , it may be formed into a coil shape. Further, a Cu-based shape memory alloy can also be used. Furthermore, methods for providing a conductive layer include mechanical joining such as pressure welding, welding, brazing, and pressure bonding, surface treatment methods such as plating, thermal spraying, vapor deposition, CVD, and sputtering, and ion sputtering to form conductive layers inside the shape memory alloy. Methods such as conversion can be adopted. Then, after forming the conductive layer, if heat treatment is performed at 450 to 800° C., a diffusion bonding layer is obtained, so that peeling of the conductive layer can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an actuator according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a current supply device in the same actuator, and FIG. 3 explains one supply form of current supplied to a shape memory element. FIG. 4 is a diagram for explaining the main parts of an actuator according to another embodiment of the present invention, FIG. 5 is a diagram for explaining the operation of the same actuator, and FIG. FIG. 2 is a schematic configuration diagram of an actuator according to an example. 10.10a, 10C-...actuator, 12.
12a, 12b--Shape memory element, 14.131 ・
...Current supply device, 24.100...Alloy plate, 25.
26.27.28.29.101.102.103.1
04... Conductive layer.

Claims (2)

[Claims] (1) It is configured to obtain the operating amount by the displacement of a shape memory element formed of a shape memory alloy member that recovers its memorized shape when heated to a predetermined temperature, and controls the shape recovery of the shape memory element. In the actuator, the actuator is actuated by Joule heat generated by a current supplied to the shape memory element itself, wherein a conductive conductor is provided over a plurality of locations on the surface of the shape memory element and divides the shape memory element into a plurality of sections. An actuator comprising: a conductive layer; and a current supply device that independently supplies current to each section using the conductive layers as electrodes. (2) The current supply device is characterized in that it is equipped with one power source and sequentially supplies current to the specified sections for short periods of time so that current always flows in only one section of the specified sections. An actuator according to claim 1.