JPH01214271A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To enhance the torque and efficiency of an ultrasonic motor by alternately disposing in series two or more vibrators and a movable body. CONSTITUTION:In an annular ultrasonic motor, vibrators 3, 10 are so disposed in series as to hold a movable body 7. The vibration 3 is composed by adhering an annular piezoelectric element 2 to an annular elastic element 1. Similarly, the vibrator 10 is composed by adhering an annular piezoelectric element 9 to an annular elastic element 8. The body 7 is composed by adhering wear resistant frictional materials 4, 6 and an elastic element 5, and brought into contact through frictional materials 4, 6 with the vibrators 3, 10. Thus, the vibrators 3, 10 and the body 7 are alternately composed in series with arbitrary numbers, thereby providing a motor having a large output and large torque weight ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic motor that generates driving force using a piezoelectric material.

BACKGROUND OF THE INVENTION In recent years, a driving voltage of several tens of KHz is applied to a vibrating body using a piezoelectric body such as a piezoelectric ceramic to excite elastic vibration, and the vibrating body is caused to move in an elastic motion or in a thickness motion, and this motion is used as a driving force. 2. Description of the Related Art Ultrasonic motors that rotate or linearly move a driven body (moving body) such as a rotor by pressing and driving the body are attracting attention.

Hereinafter, the conventional technology of an ultrasonic motor will be explained with reference to the drawings.

FIG. 5 is a perspective view of a toroidal ultrasonic motor, in which a toroidal piezoelectric body 55 is bonded to a toroidal elastic body 54 to form a vibrating body 5.
8. 53 is a friction material made of wear-resistant material; 52
are elastic bodies, and are pasted together to form the moving body 57. The moving body 57 is in contact with the vibrating body 58 via the friction material 53. When a voltage is applied to the piezoelectric body 55, bending motion is excited in the circumferential direction of the vibrating body 58, which becomes a traveling wave, thereby driving the movable body 57. Note that a protrusion 56 for extracting mechanical output is installed on the vibrating body 58 in the figure.

FIG. 6 shows an example of the electrode structure of the piezoelectric body 55 used in the ultrasonic motor of FIG. In the figure, the structure is such that nine elastic waves are placed in the circumferential direction. In the same figure,
A and B are electrode groups each consisting of a small region corresponding to a half wavelength, C is an electrode group corresponding to a three-quarter wavelength, and D is an electrode group corresponding to a quarter wavelength.

Electrodes C and D create a positional phase difference of 1/4 wave length (90°) between electrode groups A and B. Adjacent small electrode parts in electrodes A and B are electrodes used when polarizing the piezoelectric body 55, and the adhesive surface of the piezoelectric body 55 with the elastic body 54 is the opposite side to the surface shown in FIG. The electrodes on that surface are flat electrodes. During use, electrode groups A and B are short-circuited, as indicated by diagonal lines in FIG. 6.

A piezoelectric body of an ultrasonic motor configured as shown in FIG.

55 electrodes A and B with vl=vo ・5in(ωD ---(
1) V2=VO-CO3((,1t)
---(2) However, vO: Instantaneous value of voltage ω: Angular frequency t: Voltage expressed in time If ■1 and v2 are respectively applied,
The vibrating body has ξ:ξ0◆(cos(ωt)◆cos(kX)+5in
(ωt) Life 5in (kX)):ξO-C03((J
t-k Vibrations are excited.

FIG. 7 shows that point A on the surface of the vibrating body 58 moves in an ellipse with the major axis 2 and the minor axis 2 U due to the excitation of the traveling wave, and the movable body 57 placed under pressure on the vibrating body 58 moves in an elliptical motion. When the waves come into contact near the apex of the wave, the frictional force causes the wave to move in the opposite direction to the direction of wave movement at a rotational speed of ω:ωxU. Moreover, this speed becomes smaller than the above-mentioned V when there is slippage between the vibrating body 58 and the moving body 57. Arrow B in the figure indicates the traveling direction of the moving body 57, and arrow C indicates the traveling direction of this traveling wave. Further, the speed V of the moving body 57 described above is proportional to the instantaneous value ξO of this bending vibration.

Problems to be Solved by the Invention Although the ultrasonic motor configured as described above has a high torque-to-weight ratio, it has still been difficult to use in the field of robots and the like due to its low output. Another problem is that when multiple ultrasonic motors are used together for one movement, it is difficult to achieve highly efficient and controllable movement due to variations in the characteristics of each ultrasonic motor, and the weight becomes heavy. was there.

In view of the above, an object of the present invention is to provide an ultrasonic motor with high efficiency and high output.

Means for Solving the Problems The present invention provides a mobile device that includes at least two vibrating bodies each consisting of a piezoelectric body and an elastic body, and a mobile device that receives a moving motion by an elastic traveling wave generated by the vibrating bodies that is in surface contact between the vibrating bodies. The vibrating body and the movable body are alternately arranged in series so that the body and each of the contact surfaces receive substantially equal pressing pressure, and the elastic traveling waves of the vibrating bodies disposed on both sides of the movable body are The phase is shifted by approximately 180 degrees.

Function: With the above-described configuration, when pressing pressure is applied from both ends of the ultrasonic motor, the pressure is transmitted substantially evenly in the pressing direction. Therefore, substantially equal and uniform pressing pressure is applied to the contact surfaces between each vibrating body and the movable body.

In addition, the magnitude and direction of the force generated from the vibrating bodies on both sides of the movable body to the movable body is such that the elastic traveling waves generated by the vibrating body are approximately 180
Since the phase is shifted by one degree, the angles are equal and opposite at any point on the moving body. Therefore, how strong is the internal piezoelectric body?
Even if it moves, the resultant force on the moving body will be approximately O. Therefore, the moving body does not vibrate, and interference vibrations between the piezoelectric bodies do not occur.

Through the above-mentioned effects, an ultrasonic motor with large torque and high efficiency is realized.

EXAMPLES Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an exploded perspective view for explaining the basic configuration of the annular ultrasonic motor of the present invention. In FIG. 1, vibrating bodies 3.10 are arranged in series so as to sandwich a movable body 7 therebetween. With this arrangement, substantially uniform pressing pressure is applied to the contact surfaces between the vibrating body and the movable body. The vibrating body 3 is constructed by bonding an annular piezoelectric body 2 to an annular elastic body 1. Similarly, the vibrating body 10 is constructed by bonding an annular piezoelectric body 9 to an annular elastic body 8. Numeral 4.6 denotes a friction material made of wear-resistant material, and 5 denotes an elastic body, which are pasted together to form the moving body 7.

The moving body 7 is in contact with the vibrating body 3.10 via the friction material 4.6.

FIG. 2 shows how, in the ultrasonic motor configured as shown in FIG. 1, a movable body is moved by elastic traveling waves generated by vibrating bodies on both sides.

When the surfaces of the two vibrating bodies generate elastic traveling waves,
The moving body moves in the opposite direction to the direction of wave propagation due to frictional force. Arrow B in the figure indicates the traveling direction of the moving body 7, and arrow C indicates the traveling direction of the traveling wave. A method for shifting the phase of the vibrating body 3.10 by 180 degrees is to attach the piezoelectric bodies of both I-oscillating bodies to a phase shift of 180 degrees. By doing so, no matter how strongly the piezoelectric body vibrates, the resultant force on the moving body becomes approximately zero.

Therefore, the moving body does not vibrate, and interference vibrations between the piezoelectric bodies do not occur.

FIG. 3 is an exploded perspective view of an annular ultrasonic motor with higher torque, which is another embodiment of the present invention.

A movable body 35 is below the vibrating body 34, a vibrating body 36 is below the movable body 35, a movable body 37 is below the vibrating body 36, a movable body 37
This is an embodiment of an ultrasonic motor in which a vibrating body 38 is arranged in series below. The vibrating body 34 is constructed by bonding the annular piezoelectric body 21 to the elastic body 22 of the annular ring W'4. Similarly, the vibrating body 38 is constructed by bonding an annular piezoelectric body 33 to an annular elastic body 32. Numerals 23 and 25 are friction materials made of wear-resistant materials, and 24 is an elastic body, which are pasted together to form a moving body 35. Similarly, 29 and 31 are friction materials made of wear-resistant materials, and 30 is an elastic body, which are pasted together to form a moving body 37.

The vibrating body 36 is constructed by arranging elastic bodies 26 and 27 on both sides of a piezoelectric body 27.

FIG. 4 shows an ultrasonic motor realized based on FIG. 3.

A movable body 49 is mounted on a stator that integrates a vibration isolating table 51, a vibrating body 50, and a shaft 43 at the bottom, and a key 41 is installed on the movable body 49 so that torque is transmitted only in the rotational direction. The vibrating body 48 is placed, the movable body 47 is placed on top of the vibrating body 48, and the key 42 is installed so that the torque is transmitted only in the rotational direction onto the movable body 47. It is constructed by arranging an integrated stator. The shaft 43 is tightened with a nut 44. The torque becomes a combined torque and is transmitted to the transmission section 39 via the pin 40.

From the above embodiments, it can be seen that an ultrasonic motor can be produced by configuring an arbitrary number of vibrating bodies and movable bodies alternately in series.

As described in detail, according to the present invention, an ultrasonic motor having a large output and a high torque-to-weight ratio can be constructed, so that the practical effects are great. Further, since the pressing pressure applied to the contact surface is approximately equal, there is little variation in the characteristics of each vibrating body, and efficiency is high.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway exploded perspective view for explaining the basic configuration of an ultrasonic motor according to an embodiment of the present invention, Fig. 2 is a diagram of the operating principle of the ultrasonic motor according to the embodiment, and Fig. 3 is a diagram of the present invention. FIG. 4 is a diagram showing the configuration of the ultrasonic motor of the embodiment of FIG. 3, and FIG. 5 is a conventional annular ultrasonic motor. FIG. 6 is a plan view showing the shape and electrode structure of the piezoelectric body used in the ultrasonic motor of FIG. 5, and FIG. 7 is a diagram of the operating principle of the ultrasonic motor. 1.5.8.22.24.26.28.30.32.5
2.54...Elastic body, 2.9.21.27-33.5
5...Piezoelectric body, 3.10.34.36.38.46.
48, 50, 58... vibrating body, 4, 6, 23, 25
・29・31 ・53...Friction material, 7.35.37.
47・49・57... Moving body, 56... Projection body, 4
5.51...Boujindai, 41-42...Key, 40.
...Bin, 39...Transmission part, 43...Shaft, 44...
・Natsuto. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] at least two or more vibrating bodies consisting of a piezoelectric body and an elastic body; a movable body that is in surface contact between the vibrating bodies and receives moving motion by an elastic traveling wave excited in the vibrating bodies; and each of the contact surfaces is approximately The vibrating bodies and the movable body are alternately arranged in series to receive equal pressing pressure, and the phase of the elastic traveling wave of each vibrating body disposed on both sides of the movable body is approximately 1.
An ultrasonic motor characterized in that it is configured to be shifted by 80 degrees.