JPS60210175A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To obtain a high output by forming the peripheral surface of a vibrator as the contacting surface with a movable element in a motor for driving the element by generating a vibration wave by an electrostrictive element, and polarizing the elements into inner and outer rows, thereby efficiently generating the bending vibration in the ring surface. CONSTITUTION:A polarized ring-shaped electrostrictive element 112 is secured to the planar surface of a ring-shaped vibrator 31. The element is polarized in inner and outer rows in a plane oppositely in the polarizing direction. A movable element 35 energized by a spring 20 is planely contacted with the inner or outer peripheral surface of the vibrator 31, a frequency voltage to generate a bending vibration on the ring surface of the vibrator 31 is applied to the element 112 to drive the element 35. Thus, the bending vibration can be efficiently utilized, and the contacting area can be increased. Accordingly, high output can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a rotary type vibration 1jJ driven by progressive vibration waves.
This relates to the structure of a J-wave motor.

A vibration wave motor converts the vibration motion that occurs when a frequency voltage is applied to an electrostrictive element into rotational motion or -dimensional motion, and has a simpler structure than conventional electromagnetic motors because it does not require windings. It has been attracting attention in recent years because it is simple, compact, and can provide high torque even when rotating at low speeds.

1 and 2 show the driving principle of a conventional vibration wave motor, and FIG. 1 shows the state in which vibration waves are generated by the motor. Electrostrictive elements 2a and 2b bonded to the vibrating body 1 (usually metal) are placed on one side of the vibrating body 1 at a moderate distance.
They are arranged to spatially satisfy a phase shift of 1/4.

The vibrating body 1 is used as one electrode of the electrostrictive elements 2a and 2b, and the electrostrictive element 2a is supplied with ■ = VO sin ωt from the AC IQ power source 3a.
, an AC voltage of v=v□sin (ωt±π/2) with input/four phases is applied to the electrostrictive element 2b through a 90″ phase shifter 3b. The phase shifter 3b changes υ depending on the direction in which the moving body 5 is moved.
−) side, and the electrostrictive element 2b has ■=V□5.
Assume that a voltage of in(ωt-π/2) is applied.

Only the electrostrictive element 2a has a voltage v=v□ s i nω
When vibration occurs due to t, vibration occurs due to standing waves as shown in FIG.
=VQsin (ωt-π/2), vibration occurs due to a standing wave as shown in FIG. 2(b). When the two phase-shifted AC voltages are simultaneously applied to each electrostrictive element 2a, 22b, the vibration wave becomes progressive. (a) is time t=2nπ/ω, (b) is t=π/2ω+2
nπ/ω, (c) is when t=π/ω+2nπ/ω, and (d) is when t=3π/2ω+2nπ/ω, and the wavefront of the vibration wave advances in the X direction.

Such progressive vibration waves are accompanied by longitudinal waves and transverse waves, and if we focus on the mass point A of the vibrating body l as shown in Fig. 2, we can see that it forms an ellipse of revolution in the counterclockwise direction with a longitudinal amplitude U and a transverse amplitude W. I'm exercising. Since the movable body 5 is in pressure contact with the surface of the vibrating body 1 and is in contact only with the apex of the vibrating surface (actually, it is in surface contact with a certain width), the mass points A and A at the apex are The moving body 5 moves in the direction of the arrow N, driven by the component of the longitudinal amplitude U of the elliptical motion of ', . . . . If the phase is shifted by +90° using a 90@ phase shifter, the vibration wave will proceed in the -X direction, and the moving body 5 will move in the opposite direction to the N direction.

FIG. 3 shows the structure of a rotary vibration wave motor that uses this vibration wave motor to generate rotational motion. FIG. 4 is a sectional view thereof. In FIG. 3, 11 is an elastic vibrating body mainly made of metal, 12 is an electrostrictive element joined to the vibrating body 11, 15 is a movable body that presses into contact with the vibrating body 11,
16 is a rotating disk (rotating shaft), 17 is a vibration absorber that supports the vibrating body it, and 18 is a fixed body.

A frequency voltage is applied from an external power source to an electrostrictive element 12 having a structure similar to that of the electrostrictive element 2, and a driving frequency is set such that the vibrating body 11 resonates. Frictional force acts on the movable body 15 that is pressed into contact with the vibrating body 11 via the thrust bearing 9 by the spring 20, and the rotating shaft 16 joined to the movable body 15 rotates. The fixed cover 21 is fixed to the fixed body 18 with screws 22, and has a structure in which the ultrasonic vibration of the vibrating body 11 is not transmitted to the fixed body 18 by inserting a vibration absorber 17 between the electrostrictive element 12 and the fixed body 18. It becomes.

However, when this vibration wave motor is rotated, since the vibrating body 11 has a ring shape, it not only vibrates in the mode shown in Fig. 2, but also vibrates in a direction perpendicular to the ring surface. Bending vibration occurs in the direction, and twisting occurs around the circumferential direction of the ring surface as shown in Figure 5, and both bending vibration perpendicular to the ring surface and twisting around the circumferential direction of the ring surface occur. . Here, in the vibration wave motor, since the moving body 15 is driven using the traveling wave caused by the bending vibration generated in the direction perpendicular to the ring surface, the torsional component number of the vibration generated around the circumferential direction of the ring surface is determined. Since the traveling waves were not used effectively, the energy of the torsional component of the vibration generated around the circumference was lost.

Therefore, there is a drawback that the efficiency of the vibration wave motor is reduced.

Furthermore, since the amplitude of the torsional component of the vibration around the circumferential direction of the ring surface of the vibrating body 11 increases from the inner diameter side to the outer diameter side of the ring surface as shown in FIG. The elliptical motion of the mass point that occurs in the curve increases from the inner diameter side to the outer diameter side. As a result, the movable body 15 mainly contacts the outer diameter side portion of the ring surface, and does not contact the inner diameter side portion of the ring surface of the vibrating body 11.

That is, the contact area between the movable body 15 and the vibrating body 11 becomes substantially small, and the efficiency with which the traveling wave of the vibrating body 1 is transmitted to the movable body 15 decreases, resulting in a disadvantage that a sufficient output cannot be obtained.

In view of this, instead of using the vibration of the torsional component of the amplitude around the circumferential direction of the ring surface to drive the motor, a method has been considered that uses in-plane bending vibration to the ring surface to drive the moving body. It is being In-plane bending vibration of the ring surface will be explained using FIG. 6.

FIG. 6 is a diagram showing the bending vibration within the ring plane of the vibrating body 11 and the electrostrictive element 12, and is a diagram obtained by analyzing the natural vibration mode of the vibrating body 11 using the finite element method.

(When the wave number is 3) In Fig. 6, 11' is a vibrating body, and the minute units to be analyzed by the finite element method are divided into lattices. 11'' indicates that the vibrating body 11' is causing in-plane bending vibration, and only the inside and outside of the vibrating body are shown. Figure 6 expresses the in-plane bending vibration of the vibrating body 11 in an easy-to-understand manner. Therefore, the magnitude of the amplitude of the in-plane bending vibration is exaggerated.The frequency f2 suitable for causing the in-plane vibration can be determined by the following formula.

Here, A: sectional view of the vibrating body, E: Young's modulus, n: wave number of vibration, r: half of the vibrating body ring. A method of arranging the electrostrictive element 12 of a conventionally used vibrator is shown in FIG.

Incidentally, FIG. 7 is a plan view showing the arrangement of the electrostrictive element 12. In Figure 7, the O'' phase pole is 12a, and the ±90° phase pole is 1
2b are shown and are separated by λ/4 from each other, in this case showing an example of a wave number of 6.

However, the conventional method of arranging the electrostrictive element 12 has the disadvantage that the amplitude of the in-plane bending vibration shown in FIG. 6 cannot be increased. Therefore, there were drawbacks in that efficiency could not be improved and output could not be increased.

In view of this point, it is an object of the present invention to provide a vibration wave motor in which an electrostrictive element is arranged to cause in-plane bending vibration of a vibrator.

FIG. 8 is a sectional view of a vibration wave motor according to an embodiment of the present invention.
FIG. 9 is a plan view showing the arrangement of the electrostrictive element 112. In FIG. 8, 112 is an electrostrictive element, 35 is a movable body, and 36 is a rotating disk, and the description of other elements that are the same as those in FIG. 4 will be omitted. In FIG.
906 phase poles are indicated by l 12b, respectively input/4#
This is the same as the conventional example shown in FIG. This is also an example of wave number 6. However, the difference is that electrostrictive elements with different polarization directions are arranged in two inner and outer rows. Therefore, when the outer electrostrictive element extends in the longitudinal direction, the inner electrostrictive element contracts, and when the outer electrostrictive element contracts, the inner electrostrictive element stretches, causing bending vibration within the ring plane. 10(a) is a cross-sectional view showing a cross section of a friction drive unit made of an electrostrictive element 112, and FIG. 10(b) is an example in which the inner diameter surface of the vibrating body is the contact surface with the moving body. This is an example in which the outer diameter surface of the vibrating body is the contact surface with the moving body. According to the embodiment shown in FIG. 1O, the inner diameter surface or outer diameter surface of the vibrating body is used as the contact surface with the moving body, and vibration within the ring surface can be used for driving. Actually, as shown in FIG. 1O, the contact surface has a certain inclination with respect to the ring surface, and is designed to have self-centering properties.

As explained above, by using the inner diameter or outer diameter surface of the vibrating body as the contact surface with the moving body, and arranging the electrostrictive element where bending vibration within the ring surface is likely to occur, bending vibration within the ring surface can be suppressed. Since the contact area can be efficiently used for driving and the contact area can be expanded according to the thickness of the vibrating body, high output can be obtained. Further, since the contact surface is inclined with respect to the ring surface, it has self-aligning property and stable output with little rotational unevenness can be obtained.

Furthermore, since a flat plate-shaped electrostrictive element is used, it is easy to open the park, and the third
Figure 4 is a perspective view and sectional view of the conventional example, and Figure 5 is a perspective view and a sectional view of the conventional example, respectively.
The figure is a cross-sectional view showing the vibration of the vibrating body and moving body of a conventional vibration wave motor, FIG. 6 is a diagram showing the bending vibration within the ring plane of the vibrating body 11 and the electrostrictive element 12, and FIG. FIG. 8 is a cross-sectional view of a vibration wave motor according to an embodiment of the present invention, FIG. 9 is a diagram showing a method of arranging an electrostrictive element of the present invention, and FIG. FIG. 2 is a cross-sectional view showing a cross section of a friction drive unit including a vibrating body and an electrostrictive element.

1.11.31.41a and 41b are vibrating bodies.

5.15, 35.45a, 45b are moving objects.

2. 12 and 112 are electrostrictive elements, and 17 is a vibration absorbing bond.

Category 1 C2) χ Procedural amendment (method) Indication of the July 26, 1980 case 1982 Patent application No. 65402 Name of the invention Vibration wave motor Amendment person Relationship with the case Patent applicant's office 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (+0
0) Canon Co., Ltd. 5. Date of amendment order: June 26, 1980 (shipment date) 6. Specification subject to amendment 7. Contents of amendment

Claims (1)

[Claims] (, t) A plurality of ゛-E strain elements are joined to the plane part of the ring-shaped vibrating body in a phase difference manner, or a plurality of electrostriction elements polarized in a phase difference manner are joined to the plane part of the ring-shaped vibrating body. In a motor that applies a frequency voltage to generate a progressive vibration wave in the vibrating body, and uses the progressive vibration wave to frictionally drive a movable body that is brought into pressure contact with the vibrating body, the inner diameter surface of the vibrating body or The outer diameter surface is the contact surface with the moving body, and the electrostrictive element is arranged as follows.
A motor in which two rows of inner and outer polarization directions are arranged at 1rki intervals and the driving frequency is set to a resonant wave number at which bending vibration occurs in the plane of the vibrating ring.