JPH0880070A - Ultrasonic motor - Google Patents

Abstract

PURPOSE: To enable free traveling in a cylinder by constituting an ultrasonic motor such that it has two discs for generating elliptic vibration at the tips, and a coupling for coupling with the two discs, and two piezoelectric bodies joined to the coupling. CONSTITUTION: A motor 10 has two disclike elastic substances 10a and 10b, and two piezoelectric materials 15 are stuck to the surface of the coupling 10c. And, when the piezoelectric substance 15 is supplied with high frequency voltages A and B, the peripheries of the discs 10a and 10b oscillates compositely, so the motor 10 travels, but in the motor 10, the elastic bodies 10a and 10b are roughly round, and besides a coupling 10 is made between them, so it can rotate freely in the direction orthogonal to the direction of advance. Therefore, it can rotate according to the condition of inclination, even if it inclines in various directions within a cylinder 50, and the inside periphery of the cylinder 50 and the outside peripheries of the discs 10a and 10b contact with each other. As a result, even in the case that the cylinder 50 meanders in all directions, it can travel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor using composite vibration (elliptic vibration) of bending vibration and longitudinal vibration.

[0002]

2. Description of the Related Art A linear type ultrasonic motor as shown in FIG.
Presented at the Japan Society of Mechanical Engineers, the Institute of Electrical Engineers, and the Japan AEM Society. "Differential degenerate vertical L1-bending B4 mode flat plate motor" is described in "222 Piezoelectric linear motor for moving optical pickup" in "Proceedings of the 5th Symposium on Dynamics Related to Electromagnetic Force" of this society. Has been done.

This flat plate motor is constructed so as to drive a rectangular flat plate in a vertical L1 mode and a bending B4 mode in two phases to obtain a driving force by utilizing a composite vibration (elliptical motion) of the displacement, and it is required to travel on the ground surface. You can

[0004]

However, since the two legs of this ultrasonic motor are flat for contact with the ground, they can be used in circular pipes (for example, earth pipes, water pipes, wiring pipes such as electric cords). Etc.) cannot be driven. In particular, circular pipes running through the ground or the inner wall of a building are difficult to run because they have an infinite number of vertical and horizontal windings.

Therefore, it is an object of the present invention to provide an ultrasonic motor which can freely travel in a circular pipe.

[0006]

The ultrasonic motor of the present invention has two disk bodies (10) in which elliptical vibration is generated at the tip.
a, 10b) and a connecting part (10
c) and two piezoelectric bodies (15) bonded to the connecting portion.

[0007]

The operation principle of the ultrasonic motor will be described with reference to FIGS. 7 and 8. This ultrasonic motor includes a plate-like elastic member 1 and a pair of driving force extracting portions 1
It is composed of a and 1b and piezoelectric elements (PZT etc.) 2 and 3. The ultrasonic motor applies high-frequency voltages A and B to the two piezoelectric elements 2 and 3 to cause a combined vibration of bending vibration and longitudinal vibration on the plate-like elastic member 1, and thereby the driving force extracting portion 1a. And 1b, the driving force is generated by causing elliptical motion at the tips of the points 1b and 1b. Incidentally, G is a ground. The two piezoelectric elements 2 and 3 are polarized so that their polarities are in the same direction, and the high frequency voltage A,
B has a time phase difference of π / 2. There is no problem even if the polarization directions of the two piezoelectric elements 2 and 3 are opposite to each other.

The left diagram of FIG. 7 shows changes with time of the two-phase high frequency voltages A and B input to the ultrasonic motor at t1 to t9. The horizontal axis of the left diagram of FIG. 7 indicates the effective value of the high frequency voltage. The middle left diagram of FIG. 7 shows the state of deformation of the cross section of the ultrasonic motor, and shows the temporal change (t1 to t9) of the bending vibration generated in the ultrasonic motor. The middle part of the right side of FIG. 7 shows how the cross section of the ultrasonic motor is deformed, and shows the temporal change (t1 to t9) of the longitudinal vibration generated in the ultrasonic motor. The right diagram of FIG. 7 shows a temporal change (t) of the elliptic motion generated in the driving force extracting portions 1a and 1b of the ultrasonic motor.
1 to t9) are shown.

The operation of the ultrasonic motor is changed with time (t1
~ T9) will be described. At time t1, in the left diagram, the high frequency voltage A generates a positive voltage, and similarly, the high frequency voltage B generates the same positive voltage. In the middle diagram on the left, bending vibrations due to high-frequency voltages A and B cancel each other out,
The mass points Y1 and Z1 have zero amplitude. Further, in the middle diagram on the right, the longitudinal vibrations due to the high frequency voltages A and B are generated in the extending direction. The mass points Y2 and Z2 show the maximum elongation around the node X, as indicated by the arrow. As a result, the above two vibrations are combined, and the composite of the mass points Y1 and Y2 becomes the mass point Y,
Further, in the right figure, the composite of the mass points Z1 and Z2 becomes the mass point Z.

At time t2, as shown in the left figure, the high frequency voltage B becomes zero and the high frequency voltage A generates a positive voltage. As shown in the middle diagram on the left, bending vibration is generated by the high-frequency voltage A, the mass Y1 oscillates in the positive direction, and the mass Z1 oscillates in the negative direction. Further, as shown in the middle diagram on the right, longitudinal vibration is generated by the high frequency voltage A, and the mass points Y2 and Z2 are generated at time t1.
Shrink more than when. As a result, as shown in the right figure, both of the above vibrations are combined, and the mass points Y and Z move clockwise from the time t1.

At time t3, the high frequency voltage A generates a positive voltage, and the high frequency voltage B similarly generates the same negative voltage, as shown in the left figure. As shown in the middle diagram on the left, flexural vibrations due to high-frequency voltages A and B are combined and amplified,
The mass point Y1 is amplified in the positive direction from the time t2 and shows the maximum positive amplitude value, and the mass point Z1 is amplified in the negative direction from the time t2 and shows the maximum negative amplitude value. Further, as shown in the middle diagram on the right, the longitudinal vibrations due to the high frequency voltages A and B cancel each other out, and the mass points Y2 and Z2 return to their original positions. As a result, as shown in the right figure, both of the above vibrations are combined and the mass Y
And Z move clockwise from the time t2.

At time t4, the high frequency voltage A becomes zero and the high frequency voltage B produces a negative voltage as shown in the left figure. As shown in the middle diagram on the left, bending vibration occurs due to the high frequency voltage B, the amplitude of the mass point Y1 decreases from the time t3, and the amplitude of the mass point Z1 decreases from the time t3. Further, as shown in the middle diagram on the right, longitudinal vibration is generated by the high frequency voltage B, and the mass points Y2 and Z2 contract. As a result, as shown in the right figure, both vibrations are combined, and the mass points Y and Z move clockwise from the time t3.

At time t5, the high frequency voltage A produces a negative voltage and the high frequency voltage B produces the same negative voltage as shown in the left figure. As shown in the middle diagram on the left, the bending vibrations due to the high-frequency voltages A and B cancel each other out, and the masses Y1 and Z1 have zero amplitude. Further, as shown in the middle diagram on the right, the longitudinal vibrations due to the high frequency voltages A and B are generated in the contracting direction. The mass points Y2 and Z2 are, as shown by the arrows,
Maximum contraction around node X is shown. As a result, as shown in the right figure, both of the above vibrations are combined, and the mass points Y and Z move clockwise from the time t4.

As the time changes from t6 to t9, bending vibration and longitudinal vibration are generated similarly to the above-mentioned principle,
As a result, as shown in the right figure, the mass points Y and Z move clockwise and make an elliptic motion. Based on the above principle, this ultrasonic motor is configured to generate an elliptic motion at the tips of the driving force extracting portions 1a and 1b to generate the driving force.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an ultrasonically driven motor 10 according to a first embodiment of the present invention. The motor 10 is 2
It has two disk-shaped elastic bodies 10a and 10b. The two elastic bodies 10a and 10b are connected by a connecting portion 10c which is smaller than the cross section of the disk-shaped elastic bodies 10a and 10b. The cross-sectional shape of the connecting portion 10c may be a circular shape (including an ellipse) or a polygonal shape such as a quadrangular shape (see FIG. 3 described later). Hard metal such as stainless steel or Invar material is used for the elastic body and the connecting portion.
Such a motor 10 has two elastic bodies 10a and 10b.
The connecting portion 10c may be manufactured by welding or may be cut out from a cylindrical member.

Two piezoelectric materials (for example, PZT) 15 are attached to the surface of the connecting portion 10c. The high frequency voltages A and B described in FIGS. 6 and 7 are input to the two piezoelectric materials 15. FIG. 2 shows how the motor 10 travels in the circular pipe 50. FIG. 2A shows the view seen from the traveling direction side of the motor 10, and FIG. 2B shows the view seen from the side orthogonal to the traveling direction of the motor 10.

When the high frequency voltages A and B are supplied to the piezoelectric body 15, the outer peripheral portions of the disk portions 10a, 10b vibrate in the traveling direction and expand or contract in the radial direction, so that the motor 10 runs. In the motor 10 of the first embodiment, since the elastic bodies 10a and 10b are substantially circular and the connecting portion 10c is formed at the center thereof, they can freely rotate in the direction orthogonal to the traveling direction. it can. Therefore, even if the circular pipe 50 is tilted in various directions, the circular pipe 50 can be rotated according to the degree of inclination, and the inner peripheral surface of the circular pipe 50 and the outer peripheral surfaces of the disk portions 10a and 10b always come into contact with each other. Therefore, even when the circular pipe 50 is inexhaustibly twisted vertically and horizontally, it can travel.

On the other hand, since the motor 10 can move in various directions inside the circular pipe 50, the disk portions 10a, 1a of the motor 10 are
The entire outer circumference of 0b comes into contact with the inner circumferential surface of the circular pipe 50. Therefore, high frequency voltages A and B are applied to the piezoelectric body 15.
There is a problem of how to handle the power cord for supplying power. In order to solve this problem, holes 10d are provided in a part of the disk-shaped elastic bodies 10a and 10b. Further, the connecting portion 10c also has a tubular shape. And the hole 10d
The high frequency voltages A and B are supplied to the piezoelectric body 15 through the power cord 16.

FIG. 3 shows a sectional view of the connecting portion 10c. 3A and 3B show the case where the connecting portion 10c is a tube having a quadrangular cross section. 3C and 3D show the connecting portion 10c.
Shows the case of a tube having a circular cross section. Connecting part 10c
Is provided with a through hole portion 10e penetrating from the inside to the outside of the pipe. Therefore, the power cord 16 is connected to the piezoelectric body 15 from the hole 10d through the inside of the pipe of the connecting portion 10c. In addition, in FIG. 3, the piezoelectric body 15 corresponds to the through-hole portion 1.
Although it is bonded so as to cover 0e, the through hole 1
It is not necessary to cover and bond 0e.

FIG. 4 shows a motor 20 driven by ultrasonic waves according to the second embodiment. The same parts as those in the first embodiment are designated by the same reference numerals. In the first embodiment, the elastic body has a disk shape, but in the second embodiment, the elastic body is composed of tunnel types 20a and 20b. this is,
Since it is sometimes desired that the motor 20 not only move in the circular tube 50 but also move on a flat surface, it can be used in both cases. The connecting portion 20c
Must be formed above the center of gravity of the tunnel-type elastic bodies 20a and 20b. Otherwise, the corner will be down in the circular tube 50.

FIG. 5 shows the motors 10 and 2 of the first and second embodiments.
In order to increase the displacement amount of the composite vibration (elliptic motion) of the outer peripheral portion of the elastic body 10a of 0, the rigidity of the elastic portions 10a and 20a is reduced. That is, the elastic portions 10a, 2
A through hole is provided near the outer periphery of 0a. In addition, FIG.
The elastic portion 10a of the motor 10 of the first embodiment is such that the width of the elastic body becomes narrower from the center of the elastic body to the outer periphery. This also makes it possible to increase the amount of displacement of the composite vibration (elliptic movement) and increase the moving speed.

[0022]

According to the ultrasonic motor of the first aspect, since the elastic body has the circular portion on the outer peripheral portion, the ultrasonic motor can travel in the circular pipe. According to the ultrasonic motors of claims 2 to 4, the cable for high-frequency voltage supplied to the piezoelectric body does not interfere with traveling.

According to the ultrasonic motor of the fifth aspect, since the composite vibration of the elastic body is increased, the vibration efficiency is improved and the moving speed of the ultrasonic motor is increased.

[Brief description of drawings]

FIG. 1 is a perspective view of an ultrasonic motor according to a first embodiment.

FIG. 2 is a schematic diagram when the ultrasonic motor of the first embodiment travels in a circular pipe.

FIG. 3 is an enlarged view of a connecting portion of the ultrasonic motor according to the first embodiment.

FIG. 4 is a perspective view of an ultrasonic motor according to a second embodiment.

FIG. 5 is a conceptual diagram for increasing the efficiency of composite vibration of an elastic body.

FIG. 6 is a conceptual diagram for increasing the efficiency of composite vibration of an elastic body.

FIG. 7 is an explanatory diagram of an operation in a modified degenerate vertical L1-bending B4 mode.

FIG. 8 is a view showing a flat motor in a modified degenerate vertical L1-bending B4 mode.

[Explanation of symbols]

 10, 20 Ultrasonic motor 15 Piezoelectric body 10a, 20a Elastic body 10c, 20c Connection part

Claims (5)

[Claims] 1. An ultrasonic motor capable of relative movement by a composite vibration generated by a longitudinal vibration mode and a bending vibration mode, wherein the composite vibration has a circular portion generated at a tip portion.
One elastic body, and two piezoelectric bodies that are connected to the two elastic bodies and that are joined to the connection portion and that generate mechanical vibration by being supplied with a high-frequency signal. And ultrasonic motor. 2. The ultrasonic motor according to claim 1, wherein a hole is formed in a part of the elastic body. 3. The ultrasonic motor according to claim 1, wherein the connecting portion has a hollow portion. 4. The linear ultrasonic motor according to claim 3, wherein a through hole is formed so that an outer surface of the connecting portion and the hollow portion are connected to each other. 5. The linear ultrasonic motor according to claim 1, wherein the elastic body becomes less rigid as it goes from the central portion to the outer peripheral portion of the elastic body.