JPH038080Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a piezoelectric ultrasonic motor that utilizes vibrations produced by piezoelectric ceramics.

[Technical background of the invention and its problems]

Conventionally, to convert electrical energy into mechanical energy, the method used was to first convert the electrical energy into magnetic energy, and then use the magnetic attraction and repulsion to obtain mechanical energy. Motors are widely used. However, this method has problems such as a complicated and heavy structure, leakage of magnetic flux to the outside, inrush current when the power is turned on, and high back electromotive force generated when the power is turned off. For this reason, in recent years, piezoelectric ultrasonic motors have been proposed that utilize vibrations produced by piezoelectric ceramics such as BaTiO ₃ and PZT. FIG. 7 shows an example of the configuration of a piezoelectric linear motor. An elastic rail 1 made of an elastic material such as metal or plastic; a piezoelectric vibrator 2 made of piezoelectric ceramic such as BaTiO ₃ or PZT; and the rail 1.
It is composed of a sliding body 3 that is brought into pressure contact with. When either one of the piezoelectric vibrators 2 is driven with an alternating voltage at the resonant frequency of the piezoelectric vibrator 2, the elastic rail 1
An elastic body as shown in the enlarged view in FIG. 8 is generated and propagates on the rail 1. At this time, the mass point 4 on the surface of the elastic rail 1 is moving in an ellipse in the opposite direction to the direction of wave propagation, and this wave has a vertex 5 for each wavelength.
When the sliding body 3 is brought into pressurized contact with the rail 1 by holding it, the surface of the sliding body 3 in contact with the rail 1 contacts only the apex 5 of the elastic wave, so the sliding body 3 is affected by the frictional force with the rail 1. Therefore, it moves in the direction opposite to the direction of elliptical motion, that is, the propagation direction of the elastic wave. The piezoelectric vibrator 2 which is not driven in FIG. 7 performs impedance matching so that the elastic waves generated on the rail 1 propagate efficiently on the rail 1.

Such piezoelectric ultrasonic motors have a simple structure, can directly obtain linear motion, and have high positional accuracy because the sliding body is fixed on the rail by friction when stopped, but on the other hand, rotary motion is Moreover, since the force generated on the sliding body is proportional to the number of waves existing at the contact portion between the rail and the sliding body, it has the disadvantage of increasing the size in order to obtain a large force.

[Purpose of invention]

The purpose of this invention is to obtain a rotary piezoelectric ultrasonic motor with large torque.

[Summary of the idea]

The piezoelectric ultrasonic motor devised consists of a ring made of an elastic material such as metal or plastic with a part cut out, and a ring fixed at right angles to the plane formed by the ring across the cut out part. It is equipped with two piezoelectric vibrators and a sliding disk that is pressed into contact with the opposite surface of a ring to which the piezoelectric vibrators are fixed.

[Example of idea]

As shown in the front view in FIG. 1, in the plan view in FIG. 2, and in the side view in FIG. . The ring 11 has, for example, a circular or angular cross section (including polygons such as triangles and hexagons), and there are two pieces perpendicular to the plane formed by the ring 11 with the cutout 12 in between. The piezoelectric vibrators 13 and 14 are fixed by welding, brazing, or the like. Further, the sliding disk 15 is brought into pressure contact with the surface opposite to the surface on which the piezoelectric vibrators 13 and 14 are fixed, and the pressure contact of the sliding disk 15 is made by using a spring or the like to bring the sliding disk 15 into pressure contact. and is strongly pressed against the ring 11. Note that 16 is a shaft provided on the sliding disc 15 to which various devices are attached. In the piezoelectric ultrasonic motor having such a configuration, one of the piezoelectric vibrators 13 and 14, for example 13, is driven with an alternating voltage at the resonant frequency of the piezoelectric vibrator 13, and the other piezoelectric vibrator 14 is driven with a resistor. When the impedance is matched by connecting an inductor and an inductance, the vibration generated in the piezoelectric vibrator 13 causes the ring 1 to
An elastic wave is generated at 1, and the elastic wave propagates on the ring 11 in the direction of the piezoelectric vibrator 14 for impedance matching. At this time, the mass point on the ring 11 is moving in an ellipse in the direction opposite to the traveling direction of the elastic wave, as shown in FIG. The disk 15 contacts the apex of the elastic wave and is sent by friction in the direction of the elliptical motion of the mass point in the ring 11 to perform rotational motion. Therefore, on the shaft 16 provided on the sliding disc 15,
For example, by attaching gears or pulleys, rotational motion can be guided to the outside and used as mechanical power.

Although the piezoelectric ultrasonic motor according to the present invention was explained in principle in the above embodiment, various specific structures are shown in FIGS. 4 to 6. FIG. 4 shows a case where a compression coil spring 27 is used as a means for bringing the sliding disk into pressure contact with the elastic rail, where 21 is the elastic rail, 22 is a piezoelectric vibrator, 23 is a buffer material, and 24 is a compression coil spring 27.
25 is a cushioning material holder, 25 is a sliding disc, 26 is a shaft of the sliding disc, 27 is a compression coil spring, and 28 is a case. The cushioning material 23 is used to maintain balance due to pressure when the sliding disc 25 is brought into pressure contact with the compression coil spring 27. FIG. 5 shows an example in which a leaf spring 37 is used in place of the compression coil spring 27, and FIG. 6 shows an example in which an elastic body 47 such as rubber is used. In addition, in the specific structure shown in FIGS. 4 to 6 above, an example using the case 28 was described, but in the present invention, the case does not necessarily refer only to the surrounding area; for example, the case 28 As shown in the bottom and lid portions of the case 28 in Figures 2 to 6, the structure of the piezoelectric vibrator 22 mounted on the mounting plate and the sliding disk pressed against the elastic rail using an arcuate spring is also based on the concept of the case. It includes.

[Effect of idea]

The force generated in a piezoelectric ultrasonic motor is proportional to the number of waves existing at the contact area between the rail and the sliding body where elastic waves propagate. Since it contacts the entire surface, it contacts all the vertices of the elastic waves generated on the ring 11. Therefore, there is an effect that the energy of elastic waves can be utilized to the maximum extent. Furthermore, if the piezoelectric vibrator 13 to be driven and the piezoelectric vibrator 14 for impedance matching described in the embodiment are switched, the propagation direction of the elastic waves will be reversed, and therefore the direction of rotation of the sliding disc 15 will also be reversed. You can easily change direction. Furthermore, compared to currently used electromagnetic motors, it has advantages such as a simple structure, light weight, no magnetic flux leakage, no inrush current, and no generation of back electromotive force.

[Brief explanation of drawings]

Fig. 1 is a front view showing the configuration of the piezoelectric ultrasonic motor of the present invention, Fig. 2 is a plan view, Fig. 3 is a side view, and Figs. 4 to 6 are piezoelectric ultrasonic motors of the present invention. FIG. 4 is a front cross-sectional view showing the structure of an ultrasonic motor, and FIG. 4 shows an embodiment in which a compression coil spring is used as the pressure contact means for the sliding disc, FIG. 5 shows an embodiment in which a leaf spring is also used, and FIG. The figure also shows an embodiment using an elastic body, FIG. 7 is a block diagram showing the configuration of a conventional piezoelectric linear motor, and FIG. 8 is a perspective view showing the operating principle of the piezoelectric motor. 11... Circular ring, 12... Resection part, 13, 14...
... Piezoelectric vibrator, 15... Sliding disk, 16... Axis of sliding disk.

Claims (1)

[Scope of utility model registration request] An elastic rail 2 which is made of an elastic material such as metal or plastic and has a part cut out in the case 28.
1, and the elastic rail 21 across the cut portion.
A sliding disk 25 having two piezoelectric vibrators 22 fixed at right angles to the plane formed by the piezoelectric vibrators 22 and a shaft 26 with a spring material inserted on the opposite side of the elastic rail 21 to which the piezoelectric vibrators are fixed. A piezoelectric type ultrasonic motor is provided with a shaft 26 protruding from the case, and a sliding disc 25 brought into pressure contact with an elastic rail 21 by the spring material.