JPH1189257A - Vibrating type actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibrating type actuator the supporting body of which can be moved in a presribed direction, without interposing any transmitting means that generates a frictional force, and which can generate uniformly accelerated motions. SOLUTION: A vibrator 3 is supported by a supporting body 1 to whose wheels are attached so that the body 1 can be moved in the y-direction. To the vibrator 3, angular speeds +Ωand -Ωof twisting vibrations are alternately applied by means of a piezoelectric element 4 and, simultaneously, speeds of bending vibrations +V and -V are alternately applied by means of another piezoelectric element 5. Consequently, a Coriolis force Fc is generated in the vibrator 3 and the supporting body 1 moves at uniform acceleration. No frictional force works for generating the moving force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration type actuator which moves in a predetermined direction by itself, or a vibration type actuator which continuously applies a force in a predetermined direction to a controlled object.

[0002]

2. Description of the Related Art A piezoelectric motor is an example of an actuator using a piezoelectric element. This causes the vibrating body to vibrate so as to reciprocate linearly by the piezoelectric element, or distortion around the axis is given to the vibrating body. Then, the movable body in contact with the vibrating body is continuously linearly fed by friction with the vibrating body, or the movable body is rotated around the axis by the friction.

[0003]

The piezoelectric motor is excellent in that it can realize high torque at low speed rotation and has low noise. However, since the movable body is operated by the frictional force between the vibrating body and the movable body, energy loss due to friction occurs, and the energy transmission efficiency is not always good. Further, there is a problem that a frictional force causes abrasion at a contact portion between the vibrating body and the movable body and generates heat. Further, in the conventional piezoelectric motor, it is possible to give a constant speed motion to the movable body, but it is not possible to give a constant acceleration motion.

The present invention has been made to solve the above-mentioned conventional problems, and can move a support in a predetermined direction without intervening a transmission means for generating a frictional force, and can generate a uniform acceleration movement. It is an object of the present invention to provide a vibration-type actuator capable of performing the above-described operations.

[0005]

According to the vibration type actuator of the present invention, an angular velocity applying means for alternately and periodically applying a predetermined mass and an angular velocity in a direction opposite to a predetermined axis to the mass is provided on the support. And vibration applying means for applying vibration in a direction intersecting the axis to the mass at the same cycle as the cycle in which the angular velocity in the opposite direction is applied, wherein the angular velocity and the vibration Is applied in the same direction crossing both the axis and the vibration direction, and the support is movable in a direction in which the Coriolis force acts. It is.

Further, a roller, a rail or a friction mechanism having a clutch mechanism is interposed between the support and a fixed portion on which the support moves, so that the support moves only in the direction in which the Coriolis force acts. , It is preferable not to move in the opposite direction.

[0007] For example, a vibrator having the mass is provided, and the angular velocity applying means and the vibration applying means generate a torsional vibration around the axis of the vibrator and a bending vibration in a direction crossing the axis. A composite vibration is given.

The following are examples of the structure of the vibrator. A shaft body is provided, and the shaft body has vibrators formed on both sides thereof with a central portion as a node, torsional vibrations which are opposite to each other are given to the vibrators by the angular velocity applying means, and the vibration applying means is provided. Accordingly, both vibrators are subjected to bending vibrations having phases opposite to each other in a direction crossing the axis.

Alternatively, there is provided a tuning-fork type vibrating body having a plurality of vibrators which are connected to each other at their base ends and extend in parallel, and torsional vibrations in opposite directions are applied to the vibrators by the angular velocity applying means. In addition, the vibrating means applies vibration to each vibrator so that the free end of the vibrator opens and closes.

Alternatively, a disk-shaped vibrator is provided, an angular velocity about the axis is given to the disk by the angular velocity applying means, and the disk is attached to the shaft by the vibration applying means. Vibration that alternately repeats expansion and contraction in the crossing direction is applied.

In the present invention, a support which is movable in a space or a liquid is provided, and a predetermined mass provided on the support is given angular velocities in directions opposite to each other, and this angular velocity changes. In synchronization with the period, the mass is vibrated in a direction intersecting with, preferably orthogonal to, the axis serving as the center of the angular velocity. Coriolis force is generated by the velocity of the mass due to the vibration and the angular velocity. Since the cycle of the angular velocity and the cycle of the vibration are synchronized, the Coriolis force always acts as a high frequency increasing / decreasing force in the same direction. Thus, the support moves in space or liquid. In particular, the support can be smoothly moved in the direction in which the Coriolis force acts by allowing the support to move only in the direction in which the Coriolis force acts and not in the opposite direction.

In the vibration type actuator, since the vibration force is converted into the driving force of the support, there is no portion that relies on frictional force unlike the conventional piezoelectric motor, and the movement resistance is such that the support moves. In this case, only frictional resistance, air resistance, fluid resistance, etc. are obtained, and the energy use efficiency is improved.
In addition, unlike the conventional piezoelectric motor, there is no portion that is easily worn by friction or a portion that generates heat. Therefore, a long service life can be realized, and a large amount of heat is not applied to the environment in use, which is suitable for use in a constant temperature environment.

[0013]

FIG. 1 is a perspective view showing a first embodiment of a vibration type actuator according to the present invention, and FIG. 2 (A).
(B) is an explanatory diagram of the operation mode. The support 1 is
It is movable in a space or in a liquid.
Or has a rail or the like and can be moved in the y direction. In particular, it is preferable to provide a one-way clutch roller or the like so that the support can move only in the + y direction and cannot move in the opposite direction.

A vibrator 3 having an axis O in a direction orthogonal to the y direction which is the direction of movement of the support 1 is provided on the support 1.
Is provided. The vibrator 3 has a cylindrical arm 3a.
And a weight 3b fixed to the free end of the arm 3a. The base end of the arm 3a is fixed to the upper surface of the support 1. The arm 3a of the vibrator 3 is formed of a constant elastic material. Assuming that the mass of the vibrating portion of the arm 3a of the vibrator 3 is m1 and the mass of the weight 3b is m2, the mass of the vibrating portion of the vibrator 3 is substantially M = m1 + m2.

At the base end of the arm 3a, a piezoelectric element 4 for generating torsional vibration is provided as an angular velocity applying means.
By the piezoelectric element 4, a clockwise angular velocity + Ω with respect to the axis O and a counterclockwise angular velocity −Ω opposite thereto with respect to the axis 3 are alternately applied to the arm 3a and the weight 3b at a constant period. Can be Also, a piezoelectric element 5 is adhered to both sides or one side in the x direction of the arm 3a as vibration applying means. By the piezoelectric element 5, the arm 3a and the weight 3b
A bending vibration in the x direction is given, and the arm 3a and the weight 3b
The velocity + V in the + x direction orthogonal to the axis O, and -x
And the velocity in the direction -V are given alternately.

The driving power applied to the piezoelectric element 4 and the driving power applied to the piezoelectric element 5 have the same period. As a result, the vibrator 3 generates a composite vibration of the torsional vibration and the bending vibration. Further, as shown in FIG. 2A, when the angular velocity −Ω is given to the vibrator 3, the velocity −V due to bending vibration is given, and as shown in FIG. Is given, a velocity + V due to bending vibration is given. As a result, the motion system mounted on the support 1 allows the direction (y direction) orthogonal to both the axis O direction (z direction) serving as the center of the angular velocity Ω and the vibration direction (x direction) at which the velocity V is given. Direction), the Coriolis force F
c acts, and the support 1 moves by receiving a force in the + y direction. The Coriolis force increases and decreases in the same cycle as the period of the torsional vibration and the bending vibration. The average value of the increasing and decreasing Coriolis force always acts as a moving force with respect to the support 1, and as a result, the support 1 produces a uniform acceleration motion.

If the wheel 2 is a one-way clutch roller and the support 1 is configured to be movable only in the + y direction, the Coriolis force Fc acting periodically on the vibrator 3 causes the support 1 to rotate. Can be smoothly moved in the + Y direction. Here, the Coriolis force Fc (absolute value)
Is represented by the following equation 1.

[0018]

## EQU1 ## Fc = 2 · MV · Ω

(However, Fc, V, and Ω are absolute values, respectively) Next, Ω and V are determined. Assuming that the maximum amplitude of the torsional vibration of the vibrator 3 is Aθ (rad; radian) and the maximum amplitude of the bending vibration of the vibrator 3 in the x direction is Au, the displacement amount θ of the vibrator 3 due to the torsional vibration and the displacement of the bending vibration The quantity u is
It can be approximated by the following equation.

[0020]

Equation 2 θ = Aθ · cos (ω · t) u = Au · cos (ω · t)

(However, ω = 2 · π · f. F is the vibration frequency. Since the torsional vibration and the bending vibration are synchronized, ω is the same in the torsional vibration and the bending vibration. T
Is time. Therefore, the angular velocity Ω generated in the vibrator 3 by the torsional vibration that changes with time and the velocity V generated in the vibrator 3 by the bending vibration are as follows.

[0022]

Ω = (dθ / dt) = Aθ · ω · sin (ω · t) V = (du / dt) = Au · ω · sin (ω · t)

For example, the mass M = 10 (g), the vibration frequency f = 20 (kHz), the maximum amplitude Aθ = π due to twisting
/ 180 (rad), maximum amplitude Au due to bending vibration =
1.0 (μm), the Coriolis force Fc is about 551.2 × 10 ³ (dyne), which is approximately 5
60 (g weight). Under this condition, the support 1 constantly moves while receiving the Coriolis force Fc. In addition, it is possible to always apply a pressing force to another controlled object by this actuator.

FIG. 3 is a perspective view showing a second embodiment of the vibration type actuator according to the present invention, and FIGS. 4 (A) and 4 (B) are explanatory views of its operation mode. In the vibration type actuator shown in FIG. 3, a shaft 13 having a predetermined mass is provided on the support 1.
It is installed with its axis center O oriented in the x direction. The shaft 13 is made of a constant elastic material, and is rigidly supported on the support 1 by the bracket 11 so that the center in the axial direction becomes a node of vibration. And this bracket 1
1 are the vibrator 13a and the vibrator 13
b.

Between the base ends of the vibrators 13a and 13b and the bracket 11, torsional vibration type piezoelectric elements 14, 14 are provided as angular velocity applying means. In addition, each vibrator 1
Piezoelectric elements 15 that generate bending vibration as vibration applying means are provided on both side surfaces or one side surface in the z direction of 3a and 13b.
15 is stuck. In this embodiment, the piezoelectric elements 14 and 14 apply torsional vibrations around the axis O in opposite directions to the vibrators 13a and 13b. For example, when the vibrator 13a is in the phase of the torsional vibration that generates the angular velocity -Ω, the vibrator 13b is in the phase of the torsional vibration that generates the angular velocity + Ω. When the vibrator 13a has an angular velocity of + Ω, the vibrator 13b has an angular velocity of −Ω.

The vibrator 1 is formed by the piezoelectric elements 15 and 15.
Bending vibrations in opposite directions (opposite phases) in the z direction are applied to 3a and the vibrator 13b. For example, when bending vibration having a speed −V is applied to the vibrator 13a, bending vibration having a speed + V in the opposite direction is applied to the vibrator 13b. In addition, the frequency of the torsional vibration matches the frequency of the bending vibration, and the torsional vibration and the bending vibration are synchronized.

As shown in FIG. 4A, when an angular velocity -Ω is given to the vibrator 13a, z is applied to the vibrator 13a.
The velocity -V in the direction is given, and at this time, the angular velocity + Ω is given to the vibrator 13b, and the velocity + V in the z direction is given to the vibrator 13b. Therefore, Coriolis force Fc always acts on support 1 in the + y direction orthogonal to both the axis of the torsional vibration (x direction) and the direction of the bending vibration (z direction). FIG. 4B shows a moment when the phases of the torsional vibration and the bending vibration are opposite to those in FIG. 4B. At this time,
Angular velocity Ω of torsional vibration given to vibrators 13a and 13b
4 and the direction of the velocity V due to the bending vibration are shown in FIG.
In this case, the direction is opposite to that of (A), but also in this case, a Coriolis force is generated in the + y direction, and the support 1 moves in the + y direction at a constant acceleration.

FIG. 5 is a perspective view showing a third embodiment of the vibration type actuator according to the present invention, and FIGS. 6 (A) and 6 (B) are explanatory views of its operation mode. In this vibration type actuator, as shown in FIGS. 1 and 3, a tuning fork type vibration body 20 is mounted on a support that can move in the + y direction.
However, illustration of the support 1 and the wheels 2 is omitted in FIG. The vibrating body 20 shown in FIG. 5 is formed of a piezoelectric material, a pair of vibrators 21a and 21b extend parallel to the z direction, and the base ends of the vibrations 21a and 21b are integrally connected by a connecting portion 22. ing.

Each of the vibrators 21a and 21b is dielectrically polarized in the thickness direction (x direction). On the outer surface of the vibrator 21b,
As angular velocity applying means, electrodes 23 and 24 for generating torsional vibration are formed at both edges in the y direction and at a distance in the z direction, and at the center in the y direction as vibration applying means. An electrode 25 for causing bending vibration is provided. A ground electrode 26 is formed on the inner surface of the vibrator 21b. The other vibrator 21a also has a vibrator 21b
The electrodes are formed symmetrically with the electrodes. However, an electrode may be formed only on one of the vibrators.

In the vibrating body 20, drive voltages having opposite phases whose phases are different from each other by 180 degrees are applied to the electrodes 23 and 24 serving as angular velocity applying means. Therefore, when the piezoelectric material of the vibrator 21b expands at the portion where the electrode 23 is formed,
When the piezoelectric material of the vibrator 21b contracts at the portion where the electrode 24 is formed, and then contracts at the portion where the electrode 23 is formed, the piezoelectric material expands at the portion where the electrode 24 is formed. . Therefore, torsional vibration is generated in the vibrator 21b about the axis extending in the z direction. Further, a drive voltage having the same frequency as the drive voltage applied to the electrodes 23 and 24 is applied to the electrode 25 provided at the center.
Since the electrode 25 is formed at the center of the vibrator 21b, the vibrator 21b vibrates in the x direction by the drive voltage applied to the electrode 25.

Therefore, the vibrator 21b generates a composite vibration of the torsional vibration in which the angular velocities + Ω and −Ω change alternately around the z-axis and the bending vibration in the x direction. Similarly, the vibrator 21a is provided with an electrode and is provided with a drive voltage, or the vibrator 21b is provided with an electrode only. In any case, the entire vibrating body 20 vibrates at a predetermined natural frequency. That is, the directions of the torsional vibration of the vibrator 21a and the vibrator 21b are always opposite to each other as shown in FIGS. 6A and 6B, and when the angular velocity + Ω is generated in one of the vibrators, the other is vibrated. An angular velocity -Ω is generated in the child. The vibrators 21a and 2a
The bending vibration in the x direction of 1b is caused by the vibrator 21a and the vibrator 21a.
The bending in the direction in which both free ends of b are closed and the direction in which the free ends are opened are alternately repeated. The frequency is set to be the same as the frequency of the torsional vibration and the bending vibration.

As shown in FIG. 6A, when the vibrator 21a has an angular velocity of -.OMEGA.
Has an angular velocity of + Ω, the vibrator 21a has a velocity of −V due to bending vibration, and the vibrator 21b has a velocity of + V. At this time, a Coriolis force in the + y direction is generated in both vibrators 21a and 21b. Immediately thereafter, as shown in FIG. 6B, an angular velocity + Ω is generated in the vibrator 21a and an angular velocity −Ω is generated in the vibrator 21b, and at the same time, the velocity + V is generated in the vibrator 21a.
The speed -V is generated in the vibrator 21b. At this time, the direction in which the Coriolis force Fc acting on each of the vibrators 21a and 21b is also the + y direction.

In the cross-sectional shape of each of the vibrators 21a and 21b of the tuning fork vibrator 20 shown in FIG. 5, the width in the direction in which the Coriolis force Fc acts is large, and the rigidity in the + y direction is high. Therefore, when the Coriolis force Fc acts, the vibrators 21a and 21b are hardly deformed in the + y direction,
The Coriolis force Fc tends to mainly act as a moving force on the support 1.

FIGS. 7A and 7B show a modified example of the vibrating body shown in FIG. 5, which is made of a piezoelectric material or the like. In this vibrating body, three parallel bodies whose base ends are fixed are shown. Vibrator 21
c, 21d and 21e are integrally formed. The same electrodes as the vibrator 21b shown in FIG. 5 are provided on each of the vibrators 21c, 21d, 21e or, for example, the central vibrator 21d, and all three vibrators 21c, 21d, 21e vibrate at the natural frequency. .

As shown in FIG. 7A, at a certain point, the vibrators 21c and 21e are subjected to an
When Ω occurs, an angular velocity + Ω opposite to the above occurs at the center vibrator 21d. At the same time, the vibrators 21c and 21e
Due to the bending vibration, a velocity -V is generated in the x direction, and a velocity + V is generated in the vibrator 21d. In the next phase, the angular velocity + Ω is applied to the vibrator 21c and the vibrator 21e, as shown in FIG.
The angular velocity −Ω acts on the vibrator 21d, and the vibrators 21c and 2
The speed + V acts on 1e, and the speed -V acts on the vibrator 21d. Therefore, the phase of FIG. 7A and the phase of FIG.
The Coriolis force Fc acts, and a driving force by the Coriolis force Fc is applied to the support on which the vibrating body is mounted.

FIGS. 8A, 8B, and 8C show a fourth embodiment of the vibration type actuator according to the present invention. FIG. 8A is a perspective view, FIG. 8B is a side view, and FIG. (C) is a plan view. A drive shaft 31 is provided on the support 1 having the wheels 2, and a disk-shaped vibrator 32 having a predetermined mass is fixed to an upper end of the drive shaft 31. As shown in FIG. 8B, the drive shaft 31 is provided with a torsional vibration type piezoelectric element 33 as an angular velocity imparting means. Orientation angular velocities + Ω and −Ω are provided alternately.

The vibrator 32 is made of a piezoelectric material and is polarized in the thickness direction. On the surface of the vibrator 32, drive electrodes 35a and 35b, which are divided into two in the x direction, are formed as vibration applying means, and a ground electrode is formed on the front surface on the back surface. Driving voltages having phases different from each other by 180 degrees are applied to the driving electrodes 35a and 35b. The frequency of the drive voltage is the same as the frequency of the drive voltage applied to the piezoelectric element 33 that generates the torsional vibration, and is synchronized.

As shown in FIG. 8C, the drive electrode 35a
And 35b are supplied with a drive voltage having a phase difference of 180 degrees, at one point, one half of the vibrator 32 divided in the x direction is extended and the other half is contracted. At the next point, expansion and contraction are reversed. This is called the (1,1) mode, and alternately generates velocities + V and -V in the x direction. Since the velocity in the x direction is synchronized with the angular velocities −Ω and + Ω due to the torsional vibration, the Coriolis force Fc in the y direction is applied to the support 1.
Acts, and the support 1 moves at a constant acceleration.

[0039]

As described above, in the present invention, by utilizing the Coriolis force, a driving force that does not generate a frictional force in the driving force generating portion can be exhibited. In addition, heat and abrasion hardly occur, so that it has a long life and is easy to use in a constant temperature environment. Further, uniform acceleration movement can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a vibration-type actuator according to a first embodiment of the present invention;

FIGS. 2A and 2B are explanatory diagrams of an operation mode of the actuator of FIG. 1;

FIG. 3 is a perspective view showing a vibration-type actuator according to a second embodiment of the present invention;

FIGS. 4A and 4B are explanatory diagrams of operation modes of the actuator of FIG. 3;

FIG. 5 is a perspective view showing a vibration-type actuator according to a third embodiment of the present invention;

6A and 6B are explanatory diagrams of an operation mode of the actuator of FIG. 5,

7A and 7B are explanatory diagrams of operation modes in a modified example of the actuator of FIG. 5,

8A and 8B show a vibration-type actuator according to a fourth embodiment of the present invention, wherein FIG. 8A is a perspective view, FIG. 8B is a side view, and FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 support 2 wheels 3 vibrator 4 piezoelectric element serving as angular velocity applying means 5 piezoelectric element serving as vibration applying means 13 shaft 13a, 13b vibrator 14 piezoelectric element serving as angular velocity applying means 15 piezoelectric element serving as vibration applying means 20 tuning fork Type vibrators 21a, 21b vibrators 23, 24, 25 electrodes 31 drive shafts 32 disk-shaped vibrators

Claims (5)

[Claims] 1. A predetermined mass, an angular velocity applying means for alternately and periodically applying an angular velocity in a direction opposite to a predetermined axis to the mass, and intersecting the axis with the mass. Vibration providing means for providing vibration in the direction at the same cycle as the cycle in which the opposite angular velocity is provided,
Coriolis force based on the angular velocity and the vibration speed is applied to the mass in the same direction crossing both the axis and the vibration direction, and the support is movable in a direction in which the Coriolis force acts. A vibration type actuator characterized by the following. 2. A vibrator having the mass is provided, wherein the angular velocity imparting means and the vibration imparting means cause the vibrator to generate torsional vibration around an axis and bending vibration in a direction crossing the axis. The vibration type actuator according to claim 1, wherein a composite vibration is provided. 3. A shaft body is provided, and the shaft body has vibrators formed on both sides thereof with a central portion as a node, and torsional vibrations in opposite directions are given to the vibrators by the angular velocity applying means, 3. The vibration type actuator according to claim 2, wherein the vibration applying means applies bending vibrations of opposite phases in a direction intersecting the axis to both vibrators. 4. A tuning-fork type vibrating body having a plurality of vibrators extending in parallel with their base ends connected to each other is provided, and said angular velocity applying means applies torsional vibrations in opposite directions to each vibrator. 3. The vibration-type actuator according to claim 2, wherein said vibration applying means applies vibrations to open and close a free end of each of the vibrators. 5. A disk-shaped vibrator is provided, an angular velocity about the axis of the disk is given to the disk by the angular velocity applying means, and the disk is given to the disk by the vibration applying means.
3. The vibration-type actuator according to claim 2, wherein a vibration that alternately expands and contracts in a direction crossing the axis is applied.