JPS63136985A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To control to arbitrarily switch the rotational direction of an ultrasonic motor by bonding a piezoelectric element of the same polarizing polarity to the base positions of both sides of a driver, dividing them into two groups, connecting them in parallel, and switching them by a switch to supply power thereto. CONSTITUTION:Piezoelectric elements 2a-5b are bonded on an equal angle dividing lines on the lower surface of a circular base 1 of an elastic unit, and a slider is engaged with the ends of drivers 6-9 projecting integrally from the base 1 to drive it. The elements 2a, 2b, 3a, 3b and 4a, 4b, 5a, 5b are reversely polarized, and provided in parallel as first and second groups 11, 12. The groups 11, 12 are connected through a changeover switch 13 to an ultrasonic oscillator 14, and power supply is switched to the groups 11, 12 by this switching. As a result, the slider can be reversely rotatably operated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic motor, and more specifically, a piezoelectric element is bonded to an annular base body in which a plurality of drive elements are integrally formed. The present invention relates to an ultrasonic motor that applies an ultrasonic signal to a piezoelectric element to excite a base body at a frequency near resonance, thereby causing a slider engaged with a driver to rotate.

[Conventional technology]

What is shown in FIGS. 5 and 6 is a conventional ultrasonic motor previously proposed by the present inventor (Japanese Patent Application No. 181866/1982), which has an annular base 31 and four drive elements 32a. −'
s 2 d is integrally formed in a protruding manner at equal dividing points, and the piezoelectric element 36 divided into four parts is joined to the base body 31, and two dashed dotted lines 34a intersect at right angles.

This is an ultrasonic unit in which the vibration node is located at the part 34k), and the drive elements 32a, 32b and 32C, 32
d vibrate in opposite phases to each other.

With the above configuration, the annular slider (not shown) engaged with the end portions of the drive elements 32a to 32d is rotated in one direction as shown by the arrow (a).

[Problem that the invention seeks to solve]

The conventional ultrasonic motor as described above has a problem in that the direction of rotation is limited to one direction and cannot be controlled to be switched arbitrarily in the left and right directions.

This invention attempts to solve such problems.
The object of the present invention is to obtain an ultrasonic motor whose rotation direction can be arbitrarily switched.

[Means for solving problems]

In the ultrasonic motor according to the present invention, piezoelectric elements of the same polarization property are bonded to the base portions on both sides of the drive element, and these piezoelectric elements are divided into two groups with every other piezoelectric element in the circumferential direction. Piezoelectric elements are connected in parallel, and a switch is provided to switch between groups and supply power.

[For production]

In this invention, an alternating signal is applied to the first group of piezoelectric elements to excite the base body near resonance. Accordingly, the tip of the driver vibrates in a predetermined direction, causing the slider to rotate in one direction. From this state, when power is supplied to the second group by switching the switch, the slider rotates in the opposite direction.

Additionally, by using a rotary encoder, the rotation angle or rotation speed can be controlled at any desired angle.

〔Example〕

1 to 6 show an embodiment of the present invention, and FIG.
In FIG. 2, piezoelectric elements 2a, 2b, and 3a having a piezoelectric effect d31 are disposed on the lower surface of an annular base 1 made of an elastic material such as iron or aluminum.

3b, 4a, 4b and 5a, 5b are joined on equal angle dividing lines. The driving elements 6, 7, 8, and 9 integrally formed to protrude from the base body 1 are located between the nodes and antinodes of the base body 1 when it vibrates. A slider 10 is engaged across the tips of the drive elements 6 to 9.

The polarizations of the piezoelectric elements 2a, 2b and 3a, 3b are opposite to each other, and the polarizations of the piezoelectric elements 4a, 4b and 5a, 5b are opposite to each other.

The piezoelectric elements 2a to 5b are connected as shown in FIG. That is, piezoelectric elements 2a and 2b.

'5a and 3b are connected in parallel to each other as a first group 11, and piezoelectric elements 4a, 4b, 5a and 5b are connected in parallel to each other as a first group 11.
are connected in parallel to each other as a group 12. 1st. The second group I+, +2 is connected to an ultrasonic oscillator 14 via a changeover switch 13. Reference numeral 15 denotes a feedback signal extraction section of a part of the piezoelectric element, and the drive frequency of the piezoelectric element is determined by the feedback signal to form a self-exciting circuit so that the piezoelectric element operates stably even with changes in external temperature and load fluctuations.

With the above configuration, the first group 1 of piezoelectric elements is now
1, each piezoelectric element 2 in FIG.
The central parts of a, 2b, 3a, and 3b (a), (wing, ()), and C> are on the upper side of the vibration.

It exhibits a resonant vibration mode in which the positions of (mouth), (he), (ho), and (gradation), which are the lower antinodes and the central portions of each piezoelectric element of the second group 12 of piezoelectric elements, form nodes. Therefore, for example, since the position of the driver element 6 is between the antinode (a) and the node (mouth), the base body 1 is tilted and the tip of the driver element 6 also moves up and down. I ended up shaking my head,
The slider 10 will be moved.

Since the piezoelectric elements 2a, 2b and 3a, 3b have opposite polarization, the drivers 6 and 7 and 8 and 9 engage the slider 10 alternately during periods e and e of one cycle of the two-phase alternating current. become.

Next, when the changeover switch 13 is switched and the second group 12 of piezoelectric elements is energized, the inclination of the driver portion is reversed and the direction of rotation of the slider 100 is also reversed.

The rotation speed of the slider 100 increases or decreases in proportion to the input voltage when the load is constant.

The tip abutting portions of the drive elements 6 to 9 are easily worn out, so
The entire structure can be made of a lightweight, high-strength material such as FRM (fiber-reinforced metal), or plastic or rubber can be used as the material on the slider side. But it is effective.

The slider 10 may be annular or disc-shaped with an axis at the center. In addition, to prevent center deviation,
It is effective to provide an annular step in the portion where the driver engages.

The output waveform of the ultrasonic oscillator 14 may be a sine wave or a rectangular wave.

In the above embodiment, the protruding direction of the driver element is parallel to the axis of rotation, but as another structure, the driver element may be formed to protrude toward the center of the annular base or in the opposite direction. Good too.

In this case, the piezoelectric elements are bonded and arranged at predetermined positions on the outer circumferential surface and the inner circumferential surface of the base, respectively. At the same time, the slider also has a circular shape that is circumscribed or inscribed in the drive element.

FIG. 4 shows another embodiment, in which the annular bases 1K and 12o
``3 open drive elements 20° 21. 22 and 25.
An example of 24,25 pairs, or 6 drivers,
Piezoelectric elements 16a are placed on both sides of each drive element 20 to 25.
18a.

16 bhl 8 b + I 6 C@l 8 Ce
l 7 a*+ 9 a + I 7 b4Tl 9
b and +7c and +9c are provided, and the piezoelectric element 16
a.

16b, 16c, 17a, 17b, 17c as the first group, piezoelectric elements j8a, +8b, 18c, 19a, +9
b and +9c are connected in parallel as a second group, and the direction of rotation is controlled by switching the energization with a changeover switch.

In this case, since the number of drive elements is large, it is suitable for high-load applications, and there is an advantage that the thickness of the base 1 can be designed to be thin.

In the above embodiments, the cases where the number of drive elements is four or six have been shown, but the number of drive elements can be selected to be any even number of four or more. Further, it is also conceivable that the driver is provided protrudingly from both the upper and lower surfaces of the base.

Further, the piezoelectric element may be formed into a ring shape, with only the electrodes individually printed and polarized in a predetermined manner. Furthermore, R(
It is also conceivable to thin out and install the l elements as appropriate.

Alternatively, in order to stabilize the position of the antinode of vibration of the annular base, a transverse groove may be provided in the antinode of the base.

〔Effect of the invention〕

As is clear from the above description, the present invention includes a pair of piezoelectric elements having the same polarization polarity bonded to the base on both sides of each of the four drive elements protruding from the annular base. These piezoelectric elements were divided into two groups, one per m-yen snow white, each connected in parallel, and the power supply to the two groups was switched using a changeover switch.As a result, the rotation direction can be easily controlled with a simple structure and operation. It has the effect of being able to switch arbitrarily.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a plan view of a main part, FIG. 2 is a side view, and FIG. 3 is a wiring diagram. FIG. 4 is a plan view of main parts of another embodiment. FIG. 5 is a plan view of essential parts of a conventional ultrasonic motor, and FIG. 6 is a side view of the motor shown in FIG. 1--Substrate, 2a, 2b, 3a, 3b, 4a, 4b. 5a, 5b @ piezoelectric element, 6, 7, 8.9 --driver, 10 @ slider, 1+, +2... 1st piezoelectric element.
2nd group, 16... selector switch. Figure 1 6-9,! I-ku Jinzi Figure 2 Figure 3 Figure 13: Sumansha Switch Figure 4

Claims (7)

[Claims] (1) an annular base from which at least four even-numbered drive elements are integrally formed in a protruding manner; piezoelectric elements having the same polarization bonded to both sides of each of the drive elements of the base; and the piezoelectric a changeover switch for dividing the elements into every other element in the circumferential direction of the base body and selectively supplying power to the first and second groups connected in parallel; An ultrasonic motor that switches between (2) The ultrasonic motor according to claim 1, wherein the piezoelectric elements are arranged on equiangular lines on the entire circumference of the base body. (3) The ultrasonic motor according to claim 1, wherein drive elements are formed between the antinodes and nodes of the vibration of the base body. (4) The ultrasonic motor according to claim 1, wherein the driver is provided on either one side or both sides of the base body in the vibration direction. (5) The ultrasonic motor according to claim 1, wherein the piezoelectric element is formed by individually printing electrodes on an integral annular element and subjecting it to predetermined polarization. (6) The ultrasonic motor according to claim 1, comprising a feedback terminal formed of either a partially divided piezoelectric element or a separate piezoelectric element. (7) The ultrasonic motor according to claim 1, further comprising a slider having a step formed at the engaging/disengaging portion of the driver element to serve as a guide for preventing extrusion.