JPS61116078A - Drive unit - Google Patents

Abstract

PURPOSE:To generate driving power by making excellent responsive use of a formal change by inserting a small pipe made of shape memory alloy into a large pipe and providing a means of forcibly flowing at least either of cooling or heating liquid into a clearance between both the pieces and the inside of the small pipe. CONSTITUTION:A small cylindrical pipe 2 is inserted into a large cylindrical pipe 1, and flow paths 3a, 3b are formed between the pipes 1, 2 and in the cylindrical pipe 2 respectively. Both the pipes 1, 2 are made of shape memory alloy respectively and fixed to a base 4 and an end plate 5. When a control valve 9 of piping 10 is closed by a control device 12, and both the pipes 1, 2 are heated through lead wires 11a, the pipes 1, 2 make an effort to shrink into a form kept in memory at high temperature to generate recovering force. Since the recovering force is stronger than the bias force of a compression coil spring 7, both the pipes 1, 2 and the spring 7 shrink to lift an object to be driven. On the other hand, when the control valve 9 is opened to supply a cooling liquid between both the pipes 1, 2 and in the cylindrical pipe 2 from its supply source, the pipes 1, 2 and the spring 7 elongate to lower the object to be driven.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a drive device using a shape memory alloy, and particularly to improving the cooling efficiency of a device suitable for exerting a large driving force.

[Background of the invention]

For drive devices (manipulators, etc.) that use conventional shape memory alloys,
As mentioned in 211-212, wire (wire diameter 0.2-0.5 mm) was mainly used as shape memory alloy, but it is not suitable for drive devices such as large robots that require large driving force. It is. This is because the force generated by the shape memory alloy is approximately proportional to the cross-sectional area of the shape memory alloy, so a wire cannot provide a sufficient cross-sectional area. In addition, since an increase in the cross-sectional area of the shape memory alloy leads to an increase in heat capacity, it is necessary to especially devise a cooling method.

[Purpose of the invention]

An object of the present invention is to provide a drive device using a shape memory alloy that exhibits a large driving force with good responsiveness.

[Summary of the invention]

The present invention is characterized in that in order to generate a large driving force, a tube is used as the shape memory alloy member, and a cooling fluid is forced to flow inside the tube, thereby improving responsiveness.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. 1st
The figure is a perspective view of a case where one small-diameter circular tube 2 is inserted inside one large-diameter circular tube 1, where 3a is the flow path created by the gap between the tubes 1 and 2, and 3b is the thin tube. This is the inner flow path of No. 2. Further, FIG. 2 is a sectional view showing an embodiment in which a plurality of circular tubes 2 having a small diameter are inserted inside one circular tube 1 having a large diameter. Furthermore, FIG. 3 shows an embodiment in which thin diameter circular tubes 2 are tightly packed inside one large diameter circular tube 1. Here, the material of the circular tube 1 with a large diameter may be made of a shape memory alloy like the circular tube 2 with a small diameter, or may be made of other metals or resins, but if a material other than a shape memory alloy is used, it has a heat insulation effect. The better the quality, the more desirable it is.

FIG. 4 shows an example of a drive device using the shape memory alloy circular tube 1°2 shown in FIG. The shape memory alloy circular tubes 1 and 2 shown in FIG. 4 have been subjected to memory treatment in advance so that they will shrink at high temperatures, and have an irreversible shape memory effect that requires external force to deform at low temperatures. 4 is the fixed end of the base;
5 is the end plate which is the movable end, and 6 is the object to be driven.

Corresponds to the fingers of a robot handle. Reference numeral 7 denotes a compression coil spring, which is one of the elastic bodies that imparts a piascus to the shape memory alloy circular tubes 1 and 2. Here, both the circular tubes 1 and 2 are fixed to a base 4 and an end plate 5. Further, 8 is a supply source of cooling fluid, which corresponds to a compressor or a blower when air is used. 9 is a control valve, 10 is a pipe, and the above three constitute a cooling system. 11 is a lead wire, and 12 is a control device including a heating power source, which controls heating and cooling depending on the situation.

Next, the operating principle will be explained. First, when heating the circular tubes 1 and 2, the control valve 9 is closed (no fluid flows), and the electric power is applied to heat the tubes through the lead wire 11a.Then, the temperature of the circular tubes 1 and 2 rises. However, it tries to shrink to the memorized shape at high temperature and generates a restoring force.This restoring force is considerably larger than the pie spacing of the compression coil spring 7, so the circular tubes 1 and 2
The coil spring 7 contracts and lifts the driven object 6. Next, when the energization heating is stopped and the control valve 9 is opened, the cooling fluid is forced to flow as shown by the arrow 13, and the circular tube 1.degree. 2 is forcibly cooled rapidly. Then, the restoring force of the circular tubes 1, 2 suddenly decreases, the piascus becomes larger, the circular tube 1.2 and the coil spring 7 extend, and the driven object 6 lowers. In the present invention, heating may be performed using a high temperature fluid. In this case, a switching valve for cooling fluid and heating fluid (in place of control valve 9) is required, but a heating power source is not required. By repeating the heating and cooling of the circular tube 1.degree.2 as described above, the driven object is moved up and down by the displacement amount Q14, resulting in a highly responsive drive device that exerts a large driving force, and can be applied as an actuator for large robots, etc. In FIG. 4, rubber, polymer, or tension coil springs may be used instead of the compression coil spring 7 as the elastic body. Furthermore, since this figure shows a structure in which fluid is discharged to the surrounding area (discharged from the end plate 5 to the vicinity thereof), it is most desirable that the fluid be harmless, such as air.

Further, when water or the like is used, it may be configured so that it is collected without being discharged from the end plate 5.

In FIG. 4, when a tube made of a material other than a shape memory alloy is used as the large diameter tube 1, it may be fixed only to the base 4 and not to the end plate 5. Figure 5 shows the area near the end plate. The length of the large-diameter tube 1 at this time should be slightly shorter than the length when the small-diameter circular tube 2 is most contracted.

In FIG. 4, when a circular tube having a reversible shape memory effect is used as the shape memory alloy circular tube, the compression coil spring 7 (elastic body) shown in the figure becomes unnecessary.

Further, it is preferable that the circular tubes 1 and 2 of the present invention have thin walls in order to enhance heating and cooling effects.

[Effects of the Invention] According to the present invention, a drive device having a good cooling effect, excellent responsiveness, and a large driving force can be obtained.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a shape memory alloy circular tube, Figures 2 and 3 are cross-sectional views of the same tube, Figure 4 is a configuration diagram of the present invention, and Figure 5 is a method of attaching the circular tube and end plate. FIG. 1... Thick diameter circular tube, 2... Thin diameter circular tube, 3...
Channel, 4... Base, 5... End plate, 6... Drive target, 7... Compression coil spring, 8... Fluid supply source,
9... Control valve, 10... Piping, 11... Lead wire, 12... Control device, 13... Fluid flow, 14...
...Displacement amount.

Claims (1)

[Claims] 1. In a drive device that performs repetitive motion by heating and cooling a shape memory alloy member, one or more shape memory alloy members are placed inside one large diameter tube. 1. A drive device comprising a means for inserting a narrow-diameter tube into which at least one of cooling or heating fluid is forced to flow into the gap between the tubes and inside the narrow-diameter tube. 2. The drive device according to claim 1, wherein a tube made of a shape memory alloy is used as the large diameter tube.