JPH0332376A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE:To reduce a size and to increase an output by outputting a rotary force from an axial elastic vibration wave from four sector-shaped piezoelectric elements. CONSTITUTION:An ultrasonic actuator is composed of a base 1, a resonator 5 of an elastic material secured to the base 1 through an ultrasonic vibrator 4, and a rotor 7 rotatably provided on the shaft of the base 1. Four radial slits 15 are formed on the resonator 5, and partitioned to sector shapes. The disc face of the rotor 7 is formed in a slightly inclined conical face. As a result, a motion equivalent to a tilting motion of a swash plate is generated at the contact face of the resonator 5 with the rotor 7.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an ultrasonic actuator that converts the deformation of an ultrasonic vibrator made of a piezoelectric element into regenerative force and extracts it. The axial deformation of the sonic vibrator is converted into a motion equivalent to the permissible rocking rotation of the swash plate.
The present invention relates to an ultrasonic actuator that extracts this as rotational output.

(Prior art) Ultrasonic actuators, which utilize the expansion and contraction of an ultrasonic vibrator made of a piezoelectric element to generate rotational force, are small, lightweight, high torque, and have small inertia, so they can be used in various control devices. It is expected to be a 6-effective driving source.

(Unexamined Japanese Patent Publication No. 58-148682, Unexamined Japanese Patent Publication No. 63-59
(See Publication No. 777) (Problems to be Solved by the Invention) However, in the Ifi1O1 wave actuator as seen in the above-mentioned Japanese Patent Application Laid-Open No. 58-148682: In order to move the actuator without any movement, it is necessary to install a large number of piezoelectric elements in circulation, and along with this, a large number of lead wires must also be installed, and efforts are still being made to make actuators smaller, lighter, and more compact. I have no choice but to guess that it will take less than 1 minute.

In addition, in conventionally known ultrasonic actuators, in principle, a constant proportional relationship is always maintained between the longitudinal wave amplitude and the transverse wave amplitude. It has been difficult to freely control the amplitude of the transverse wave that provides the supporting force for the moving body, and it has been difficult to control it in response to changes in the required load and speed.

On the other hand, the ultrasonic actuator disclosed in Japanese Patent Application Laid-Open No. 63-59777 obtains driving force by exciting bidirectional vibration waves, but those that utilize bending vibration utilize axial vibration. Although it is easy to obtain a large displacement compared to the conventional actuator, it is difficult to generate a large torque, and for this reason, it has been difficult to obtain a large torque actuator.

Also, if you want to obtain a large torque with this type of actuator, you will have to increase the voltage applied to the piezoelectric element, but this requires a high-voltage power supply and a high-voltage piezoelectric element, which requires a large drive circuit. Not only will this change the shape of the device, but the cost of the device will also increase significantly. These problems have their roots in the use of bending vibration.

On the other hand, the ultrasonic vibrator consists of a piezoelectric element consisting of an annular disk, and the piezoelectric element is polarized in a positive and negative manner in semicircles, and one side of the piezoelectric element is polarized. A ground electrode is provided, and on the other side, four electrode plates in a 90 degree fan shape are arranged, two on the + semicircular part and two on the - semicircular part, and the above four electrodes Among the plates, opposing electrode plates are short-circuited, and an alternating current voltage is applied to two adjacent electrode plates with a phase shift of 90 degrees, and two such annular piezoelectric elements are connected to each other. One of the inventors of the present invention invented an ultrasonic motor in which two electrode plates are overlapped so that their polarities match, and one distribution electrode is provided in contact with the piezoelectric element, and this is already known. . (l Kaisho 63-2
(See Publication No. 09479) The ultrasonic transducer made of the above-mentioned known piezoelectric element is named an electrostrictive rotor.

In this known ultrasonic motor, rotation of the rotor is obtained by utilizing radial deformation of the ultrasonic vibrator.

Therefore, an object of the present invention is to
Using the upper-shaped electrostrictive rotor shown in No. 9, the axial vibration of the piezoelectric element is used to realize a motion equivalent to the so-called oscillating motion of a swash plate, thereby achieving a compact, high output, The aim is to obtain an ultrasonic actuator with a simple structure.

(Means for Solving the Problems) The present invention is characterized by a rotor, a resonator made of an elastic material that partially contacts the end face of the rotor, and a resonator that vibrates the end face of the resonator in the axial direction. In an actuator comprising an ultrasonic vibrator, the actuator generates a movement equivalent to the oscillating movement of a swash plate on the contact surface between the resonator and the rotor, the ultrasonic vibrator comprising a piezoelectric element consisting of an annular disk, Polarize the piezoelectric element so that the semicircles are + and -, 1!1
3, one ground electrode is provided on one side of the piezoelectric element r, and four electrode plates in a 90 degree fan shape are provided on the other side. Two electrode plates are arranged in the area and two electrode plates are arranged in the - semicircular part, and among the four electrode plates, the electrode plates facing each other are short-circuited, and the phase of the two adjacent electrode plates is shifted by 90 degrees. 3. (Example) Hereinafter, an example of the present invention will be described. will be explained with reference to FIGS. 1 to 4.

Referring to the figure, a shaft 3 having a screw 2 is provided on a base 1 in a protruding manner. A resonator 5 made of an elastic material is fixed to the base 1 with a 'Mi sonic vibrator 4 interposed therebetween. The resonator 5 is provided with an h groove 6 into which the screw 2 of the shaft 3 is screwed,
The h-shaped groove 2 of the shaft 3 is screwed into the groove 6 and fixed.

The shaft 3 passes through the resonance T-5, and a rotor 7 is rotatably provided at the tip of the shaft 3 by means of a pole 8. The bolt 8 is screwed into a screw hole 9 formed at the end of the pongee 3, and the rotor 7 is rotatably attached using the bolt 8 as a rotation pongee. The rotor 7 is provided with a hole 10 and four parts 11 through which the bolt 8 passes. A bearing 12 and a leaf spring 13 are provided in the four parts 11, and the bolt 8 is inserted through the bearing 12 and the disk f213. The strength of the pressure bonding between the rotor 7 and the resonator 5 can be adjusted by changing the degree of tightening of the bolt 8.

Since the disk surface of the rotor 7 comes into contact with the resonator 5 as it is deformed, it has a slightly inclined conical surface, and the contact surface 14 of the resonator 5 is coated with surface hardening treatment to prevent wear. For example, heat treatment, alumite treatment, hard chrome plating treatment, etc. are performed. Note that the configuration does not necessarily require the rotor 7 to be tilted, and it may be flat as long as the rotor 7 is configured to be movable in the axial direction.

The resonator 5 is partitioned into a fan shape of 90 degrees by four radial slits 15 (see especially FIG. 4).

Note that it is also possible to have a structure that is completely divided into 90 degree sector shapes.

The ultrasonic vibrator 4 is made by polarizing the piezoelectric element 16 to 1', 1', 1', and 1', similar to the electrostrictive rotor disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 63-209479. It consists of four fan-shaped electrode plates arranged at 90 degree intervals, two stacked on top of each other, and one distribution electrode 17 in contact with the piezoelectric element 16.

A more detailed explanation of the piezoelectric element 16 is shown in FIG. 3 (A).
, (B) is shown in detail ↓ Sea urchin, - A ground electrode 18 is applied to the face of the sword, and fan-shaped electrode plates 19, 20, 21, 22 are applied to the other side at 90 degree intervals, Electrode 19.2
A positive DC voltage is applied to the electrodes 21 and 22, and a negative DC voltage is applied to the electrodes 21 and 22, resulting in remanent polarization as shown by + and - in the figure. In this embodiment, the two piezoelectric elements 16 treated as described above are connected to the four electrode plates 19.2o and 21.22 with the same polarity (+
The polarities of the negative polarities overlap each other and the negative polarities overlap each other.

Further, the distribution electrode 17 is disposed between the two piezoelectric elements 16, and is in contact with the electrodes 19.2o and 21.22, respectively, as shown in FIG. 3(c). Electrode plates 19A, 2OA.

21, A, and 22A, short-circuit electrode plate 19A and electrode plate 2]A, short-circuit electrode plate 20A and electrode plate 22A, and connect two leads a23 and 24 to each. are doing. The ultrasonic vibrator 4 has a ground electrode 1 of a piezoelectric element 1G.
A t' line 25 is provided to connect to the line 8.

The sector-shaped electrode 19.20.21.22 has a slit 1
It corresponds to the fan shape of the resonator 5 divided by 5.

]? The operation of the ultra-f wave actuator of the present invention configured as J and -L will be explained 4''.

First, the so-called swinging motion of the swash plate will be explained with reference to FIG.

The swash plate 31 swings and rotates with its top slanted, and operates in the same way.Here, the peeling plate 31 does not rotate itself, but simply swings and swings at an angle of inclination θ. However, one point on the conical surface 32 of the swash plate 31 is the rotor 33
When the conical surface 32 comes in contact with the swash plate tooth 1, the conical surface 32 frictionally drives the rotor 33 at that circumferential speed.
It is known as a speed reduction mechanism using
125443), and its reduction ratio is as follows.

That is, if the inclination angle of the swinging rotation is θ, the reduction ratio is 1/S inθ.

Now, if the displacement amount of the piezoelectric element is ΔL and the radius of the swash plate is R, then since ΔL f is minute, Sinθ=θ, and the reduction ratio is 1/S inθ=1/θ=1/(ΔL/ R)=R/
ΔL.

11 Now, in the ultrasonic actuator of the present invention, when AC voltages of the same frequency are applied to the lead wires 23 and 24 with a phase shift of 90 degrees, the electrode plates 19A, 2OA, 21A
, 22A, the piezoelectric elements 16 polarized like the electrodes 19, 20, 21, 22 expand and contract sequentially (alternately), and this vibration propagates through the resonator 5 as a longitudinal elastic vibration wave, and the contact surface 14 The rotor 7 is driven to rotate on top of this motion, which does not produce a motion equivalent to the motion that occurs when the swash plate oscillates.

The above are examples of the present invention, and the present invention is not limited to the above examples.

For example, the structure of the piezoelectric element that causes axial vibration is not limited to the above-mentioned embodiment, and may be a structure in which four piezoelectric elements having a substantially 90 degree sector shape are provided (! It is sufficient, for example, one piezoelectric element is provided. Instead of subjecting the annular disk to polarization treatment, it is also possible to adopt a structure in which four piezoelectric elements are arranged on the circumference.

Further, in the above embodiment, two piezoelectric elements are installed, but the number of piezoelectric elements of the present invention is not limited to two, and it goes without saying that one piezoelectric element may also be used. ,
It is also possible to use three or more sheets.

Furthermore, in the above embodiment, the polarized parts of the piezoelectric elements are stacked so as to face each other so that only one distribution electrode plate is required. It is also possible to have a structure in which two plates are grounded.

(Effects of the Invention) The effects of the present invention explained above are as follows.

Since the rotational force is extracted from the axial elastic vibration waves generated by four fan-shaped piezoelectric elements, it is possible to obtain a large torque and a small, high-output ultrasonic actuator, and at the same time, it is small and compact. becomes.

According to the configuration of the present invention, it is possible to easily stack two or more piezoelectric elements, so that -
A layered, high-output ultrasonic actuator can be obtained.

According to the present invention, basically only three lead wires need be installed, so wiring can be simplified.

[Brief explanation of drawings]

Fig. 1 is a front view of an ultrasonic actuator showing an embodiment of the present invention, Fig. 2 is an exploded view of the ultrasonic actuator shown in Fig. 1, and Fig. 3 (a) is a plane view of the piezoelectric element from one side. 3(B) is a plan view of the piezoelectric element seen from the other side, FIG. 3(C) is a front view showing the distribution electrode plate, FIG. 4 is a plan view of the resonator, and FIG. 5 is the main FIG. 3 is a diagram for explaining the swinging motion of the swash plate, which is the operation of the invention. 2: hji 3: pongee 4: ultrasonic vibrator 6: faji groove 7: rotor 8: bolt 0: hole 11
: Recess 12: Bearing 14: Contact surface 15 Nislit 17 Two-part electrode 19.20.21.22: Electrode 1: Base 5: Resonator 9: F2 hole 13: Disc plate h 16: Piezoelectric element 18: Ground electrode 1 9A. 0A1 2 1, A, 22A: Electrode plate 23. 24. 25: Lead wire

Claims (5)

[Claims] (1) Consisting of a rotor, a resonator made of an elastic material that partially contacts the end surface of the rotor, and an ultrasonic vibrator that vibrates the end surface of the resonator in the axial direction, contact between the resonator and the rotor In an actuator that generates a motion equivalent to the oscillating motion of a swash plate on a surface, the ultrasonic vibrator is composed of a piezoelectric element consisting of an annular disk,
The piezoelectric element is polarized in the thickness direction so that semicircles are + and -, and one ground electrode is provided on one side of the piezoelectric element, and a 90 degree fan-shaped electrode is provided on the other side. The four electrode plates thus formed are arranged, two in the + semicircular part and two in the - semicircular part, and among the four electrode plates, opposing electrode plates are short-circuited to each other, and the adjacent electrode plates are arranged. An ultrasonic actuator characterized in that an alternating current voltage is applied to two electrode plates with a phase difference of 90 degrees. (2) The ultrasonic actuator according to claim 1, wherein four radial slits are formed in the resonator, and the resonator is partitioned into a 90-degree fan shape, the same as the electrode plate. (3) The ultrasonic actuator according to claim 1, wherein the resonator is radially divided into four parts, and the resonator is arranged in the same 90 degree fan shape as the electrode plate. (4) The ultrasonic actuator according to any one of claims 1 to 3, wherein the contact surface of the resonator is subjected to surface hardening treatment. (5) The rotor and the resonator are sandwiched and fixed via an elastic body,
5. The ultrasonic actuator according to any one of claims 1 to 4, characterized in that means is provided for moving the rotor and the resonator relatively closer to each other and moving them apart to vary their mutual pressing force.