JPH0241670A - drive device - 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 drive device, and more particularly to a drive device that uses a thermal expansion and contraction element and is highly accurate and durable.

[Prior Art] A drive device that drives a drive body using ultrasonic vibrations is also called an ultrasonic motor, and has been widely used in recent years for automatic control etc. because it has advantages such as low noise and high positioning accuracy. There is.

Fig. 2 is a basic configuration diagram of an example of a conventional drive device using ultrasonic waves, and Fig. 3 is an explanatory diagram of its principle. 12, and the electrostrictive element 1 is placed on the surface of this elastic body 12.
3 is attached. Note that, although not shown, a pressure regulating mechanism is also added so that a pressure proportional to the driving force is applied. In this drive device using ultrasonic waves, as shown in FIG.
3 gives vibration to the surface of the elastic body 12, an elastic wave is generated, and this elastic wave propagates on the surface of the elastic body 12.

This elastic wave is a surface wave accompanied by longitudinal waves and transverse waves, and its mass point moves in an elliptical orbit as shown in Figure 3. In other words, if the traveling direction of the surface wave is the 10X direction, the mass point A will rotate counterclockwise. Therefore, when the driving body 11 is brought into pressure contact with the surface of this elastic body 12, the surface of this driving body 11 comes into contact with only the mass points A and A', so this driving body 11 is brought into contact with the elastic body 12. It is driven in the direction of arrow N by friction.

[Problem to be solved by the invention] Conventional driving devices using ultrasonic waves are driven by the principle described above, and because they use frictional force,
This has a serious drawback in that it is undesirable to use it for long periods of time or for applications where it is frequently used, since wear of the contact member is unavoidable and the positioning accuracy decreases.

The present invention aims to eliminate this drawback of the drive device, and provides a highly durable drive device using a thermal expansion and contraction element.
The present invention aims to provide a novel drive device with high positioning accuracy.

[Means for Solving the Problems] This invention consists of three pillar-shaped thermal expansion and contraction elements combined in an H shape to form a driving body, and two guide rails installed parallel to the end surfaces of the driving body. The above-mentioned problem is solved by positioning the drive body on the side surface and causing the drive body to move along the guide rail by passing a controlled signal current through the drive body.

[Function] When a positive signal current is applied by a signal generator to the thermally elastic element located at the rearmost position in the direction of movement among the three thermally elastic elements that make up the driving body, this heat is released. The telescopic element thermally expands in the longitudinal direction, presses against the kitrail from the inside, and is secured to it.

Next, when a positive signal current is applied to the central thermally expandable element located laterally, this thermally expandable element thermally expands in the lateral direction and pushes out the thermally expandable element located at the front in the traveling direction. Next, a signal current is applied to the extruded thermally extensible element to cause it to thermally expand in the longitudinal direction, thereby pressing and fixing the kite rail.

Thereafter, when the supply of signal current to the rear and central thermal expansion elements is stopped, they will contract to their original length and move in the direction of travel.

In this way, by supplying control current to the three thermal expansion and contraction elements in a fixed order, the driving body moves along the guide rail.

[Embodiment] FIG. 1 is a side view schematically depicting an embodiment of an ultrasonic driving device according to the present invention.

In the figure, 1 is a driving body, and there are three thermal expansion and contraction elements 2a and 2b.
, 2c are combined into an H shape.

The thermal expansion and contraction elements 2a, 2b, and 2c are elements that expand and contract by supplying a signal current, and may be electrically controlled heating elements or electronic cooling elements that utilize the Beltier effect.

These thermally expandable elements 2a, 2b, 2c are combined in an H shape to constitute a driving body 1, and the thermally expandable element 2a is placed between a pair of kite rails 8a, 8b positioned in parallel. , 2b, and 2c are positioned such that both ends thereof touch each other when extended.

Note that the spacing between the guide rails 8a, 8b is made to be slightly narrower than the length of the thermally expandable elements 2a, 2b, 2c when they are extended, so that a gap is widened when they are contracted.

In this embodiment, the kite rails 8a and 8b are installed in a straight line, but they may also be installed in an annular shape, in which case the driving body 1 will perform rotational movement.

Next, the operation of this embodiment will be explained. Three thermal expansion and contraction elements 2a constitute the driving body l.

When a positive signal current is applied by a signal generator (not shown) to the thermal expansion/contraction element 2C, which is located at the rearmost position in the direction of movement, among 2b and 2c, this thermal expansion and contraction element 2C as shown in FIG. The expandable element 2C thermally expands in the y-axis direction (vertical direction), presses the guide rails 8a and 8b from the inside, and is fixed thereto. Next, when a positive signal current is applied to the thermally expandable element 2b located laterally in the center, this thermally expandable element 2b thermally expands in the X-axis direction (lateral direction), as shown in FIG. 1(b). The thermal expansion and contraction element 2a located at the front is pushed out 66 minutes in the direction of travel. Next, a signal current is applied to the extruded thermally expandable element 2a to cause it to thermally expand in the y-axis direction (vertical direction), thereby pressing and fixing the guide rails 8a and 8b.

Then the rear and central thermal expansion elements 2b.

When the supply of signal current to 2C is stopped, they contract to their original length and move by Δα in the direction of travel, as shown in FIG. 1(C).

In this way, there are three thermally expandable elements 2a, 2b.

By supplying control currents to 2C in a fixed order, the driver l will move along the kite rails 8a, 8b.

If a thermoelectric cooling element is used for the central thermally elastic element 2b, by reversing the polarity of the signal current supplied to it and passing a negative current, the thermally elastic element 2b will be cooled and its length will be shorter than its original length. It further becomes shorter, and the amount of displacement increases to Δd', as shown in FIG. 1(d).

On the other hand, when it is desired to move the driving body 1 backward, the thermal expansion and contraction elements 2a and 2b are moved in the reverse order to the above-mentioned case.

It is sufficient to supply a signal current to 2C.

[Effects of the Invention] As described above, the drive device according to the present invention is capable of moving the drive body in any left or right direction while supplying a signal current to the drive body, and is capable of moving the drive body in any direction left or right. Since it uses the expansion and contraction action of the element, the noise level is extremely low. Also, since it does not use frictional force for driving, it does not wear out. Since it turns ON and OFF using electrical signals, it is fast and highly accurate. This method has an excellent effect in that positioning can be performed using the same method.

[Brief explanation of the drawing]

FIGS. 1(a), (b), (c), and (d) are side views schematically depicting an embodiment of a drive device according to the present invention. Further, FIG. 2 is a perspective view of a conventional example, and FIG. 3 is a diagram illustrating its principle.

Claims (1)

[Claims] Three column-shaped thermal expansion and contraction elements are combined in an H shape to form a driving body, and the end faces of the driving body are positioned on the inner surfaces of two guide rails installed in parallel, and the driving body receives a controlled signal. An ultrasonic driving device characterized in that the device is moved along the guide rail by passing an electric current through the device.