JPS61295882A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To extend a motor service life by composing the contact of a movable unit with a vibrator of many rotatable spheres, and increasing a frictional force between the spheres and the unit body by the frictional force between the spheres and the vibrator, thereby reducing the wear. CONSTITUTION:Many electromechanical energy converter 1 is mounted on a vibrating plate 2. A movable unit 3 is composed of a ringlike movable structure 3a having U-shaped section of body, an elastic unit 3b of rubber sponge formed on the bottom of the U-shape, wear resistant sphere 3c made of resin or metal contained in the U-shape, and a retainer 3d for holding the positions of the spheres 3c. Only the spheres 3c contact the plate 2, and the frictional force between the plate 3b and the sphere 3c is selected to increase from the frictional force between the plate 2 and the sphere 3c. The contacting position of the sphere 3c with the vibrator 2 moves as the motor is driven, thereby reducing the wear of the sphere 3c.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a so-called vibration wave motor that frictionally drives a moving body in contact with the vibrating body by progressive vibration waves generated in the vibrating body, and particularly to a vibration wave motor for frictionally driving a moving body in contact with the vibrating body. It's about structure.

[Background of the invention]

A known example of a vibration wave motor will be schematically explained with reference to FIGS. 6 and 7. Reference numeral 1 is an electromechanical Nehru transducer element such as an electrostrictive element or a magnetostrictive element, for example, PZT (lead zirconium titanate). Reference numeral 2 denotes a ring-shaped vibrating body made of an elastic material, and the electrostrictive element 1 is adhered to one side of the vibrating body. The vibrating body 2 is a stator (not shown) together with an electrostrictive element l.
held on the side. Reference numeral 3 denotes a moving body, which in this example forms a ring plate-shaped rotor that is pressed into contact with the other surface of the moving body 2 . A plurality of electrostrictive elements l are arranged in the circumferential direction of the vibrating body 2, and some groups of the electrostrictive elements l are arranged with a pitch shifted from other groups by 1/4 wavelength of the wavelength λ of the vibration wave. be done. The electrostrictive elements in the group are arranged at a pitch of A wavelength so that adjacent ones have opposite polarities.

In a vibration wave motor having such a configuration, when an AC voltage of Vo-8inωT is applied to the electrostrictive elements in one group and an AC voltage of KvO-CO8inωT is applied to the electrostrictive elements in the other group, each electrostrictive element becomes Neighboring units have opposite polarities, and an alternating current voltage 90@out of phase is applied to the two groups, causing them to vibrate. This vibration is transmitted, and the vibrating body 2 bends and vibrates in accordance with the arrangement pitch of the electrostrictive elements 1. This bending vibration occurs in such a way that the vibrating body 2 protrudes at every other electrostrictive element position and then retracts at every other electrostrictive element position. On the other hand, as described above, since one group of electrostrictive elements is located at a position shifted by 1/4 wavelength from the other group, the bending vibration advances in the arrangement direction of the voltage elements. While the alternating current voltage is applied, vibrations are excited one after another and become progressive bending vibration waves that propagate in the circumferential direction of the vibrating body 2.

The progress state of the wave at this time is shown in Figure 7 (a) (b) (c
) (d). Now, assume that the progressive bending vibration wave advances in the direction of arrow X1. If 0 is the center plane of the vibrating body in a stationary state, this center plane becomes a neutral plane 6 shown by a chain line in a vibrating state, and stress due to bending is balanced on this neutral plane 6. Now, the cross section perpendicular to the neutral plane 6 is generally represented by 7, the line of intersection between the cross section 7 and the neutral plane 6 is generally represented by 5, and the cross section 7 and the surface of the vibrating body 2 on the movable body 3 side are A point on the intersection line of is generally represented by P, and when these are specifically represented, they are represented by a subscript number. Looking at the cross section 7 perpendicular to the neutral plane 6, no stress is applied to the intersection line 5 of these two surfaces, and the intersection line 5 only vibrates vertically.

At the same time, the cross section 7 vibrates as a pendulum to the left and right with the intersection line 5t as the center. Therefore, point P moves in a combination of vertical and horizontal movements, which will be explained in detail next.

FIG. 7 (&) shows the state at an arbitrary point in time, and shows a cross section 71 passing through the intersection line 51 k of the plane 0 and the neutral plane 6, and the vibrating body 2.
Point P1 on the line of intersection with the surface of the moving body 3 is the right dead center of the left-right vibration, and only upward movement is possible. Line 5! Point P corresponding to !
A motion component in the left direction (X, direction opposite to the wave traveling direction The motion component of is added.

Thereafter, as the wave progresses, as shown in FIG. 7(b) K, when the intersection line 5K comes to the positive side of the wave, point P1 moves to the left and at the same time moves upward.

Furthermore, at the time point shown in FIG. Furthermore, at the time of IC(a), reading point P1 moves leftward and downward.

The wave further advances, moving to the right and downward, moving to the right and upward, and then returning to the state shown in FIG. 3(a). Other points P
The same can be said about @s P s.

Through such a series of motion processes, the point P moves in an ellipsoid of revolution, and the radius of rotation thereof is a function of the length from the neutral plane 6 of the photographing body 2 to the moving body side surface (that is, to the point P).

On the other hand, since the movable body 3 is in pressure contact with the vibrating body 2, for example, as typically shown in FIG. The spheroidal motion of P1 frictionally drives the moving body 3t-X in the direction. Not only the point P1 but all points on the surface of the vibrating body 2 on the movable body 3 side frictionally drive the movable body 3 in the same way as the point P. The above is the principle of a vibration wave motor.

By the way, in this vibration wave motor, the contact surface of the movable body with the vibrating body is composed of a large number of spherical surfaces, and an improved one is proposed in Japanese Patent Application No. 60-66 by the present applicant.
093. As a result, there is no air film trapped between the camera and the moving body while the motor is running, and the output is improved without reducing the frictional force. Also, due to the contact shape, abrasion particles are removed from the contact area. This has the advantage of preventing the motor from stopping or reducing output due to abrasion powder being swept outside, but it has the disadvantage of high contact pressure due to point contact, resulting in severe wear.

[Purpose of the invention]

An object of the present invention is to reduce the problem of wear in a vibration motor in which a moving body makes point contact with a vibrating body at multiple points, maintain the point contact state for a long time, and extend the life of the motor.

[Summary of the invention]

The structural feature of the present invention is that in the vibration wave motor, the contact portion with the vibrating body of the movable body is composed of a large number of rotatable balls,
The reason is that the frictional force between the nuclear sphere and the main body of the moving body is made greater than the frictional force between the nuclear sphere and the vibrating body.

Furthermore, in a more preferable form of the present invention, it is configured to restrict rotation of the nuclear sphere in the circumferential direction of the moving body.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 to 5. Figures 1(&) and (b) show one embodiment of the present invention,
1 is an electro-mechanical energy conversion element (for example, PZT
), 2 is a photographic plate with a large number of these attached, and the configuration of this part is different from that shown in Figure 6).

3 is a movable body, a ring-shaped movable body structure 3a having a U-shaped main body, an elastic body 3b such as a rubber sponge provided on the bottom of the U-shaped portion, and an elastic body 3b housed within the U-shaped portion. It consists of a wear-resistant ball 3c made of resin, metal, etc., and a taker 3d that holds the position of the core ball 3c. The above-mentioned members 3a and 3b and 3a and 3d are fixedly joined to each other, but the others are not joined.The vibrating body 2 is made of a metal material such as brass or steel that has low internal loss of vibration energy. It will be done. The moving body structure 3& may be made of any material such as metal or plastic as long as it can maintain its shape. Each ball 3c is positioned in a hole provided in the retainer 3d so that it partially protrudes from the hole. Only the ball 3C contacts the diaphragm 2. The frictional force between the elastic plate 3b and the ball 3C is selected to be greater than the frictional force between the diaphragm 2 and the ball 3c. For this reason, the rotational movement of the ball is almost restricted. However, the vibration from the diaphragm 2 is directly transmitted to the sphere, and in addition to the y-direction vibration, the force in two directions accompanying the movement of the mass on the surface of the diaphragm and the torsion in the (See Figure 2), the ball rotates little by little in two directions and in the X direction. Therefore, the contact position of the ball 3C with the vibrating body 2 moves with the motor drive, reducing wear on the ball.
Motor life is significantly extended.

As described above, the ball makes a slight rotational movement both in the circumferential direction and in the radial direction of the moving body. In particular, when the motor is started and stopped, the acceleration of the moving body is at its maximum and the rotational movement of the ball also increases. In particular, since there is a problem in that the rotational movement of the ball in the direction of the mobile station deteriorates the start-up and stop characteristics of the motor, an embodiment that eliminates this problem will be described next.

In the embodiment shown in FIGS. 3(a) and 3(b), an elastic body whose width in the radial direction of the movable body is smaller than the diameter of the sphere 3α extends in a band shape in the circumferential direction, and a notch provided in the elastic body extends in the circumferential direction. It comes into contact with the ball 3d in the circumferential direction.

Due to the structure of such an elastic body, the frictional force of the ball in the circumferential direction of the moving body can be made larger than the frictional force in the radial direction of the moving body, so that the ball does not easily rotate in the circumferential direction of the moving body. It is possible to eliminate the problem. Furthermore, in another embodiment shown in FIG. 4, in the embodiment shown in FIG.
If the rotation of the ball 3ci in the circumferential direction of the moving body is restricted), the above problem can be solved more effectively.

Figure 5 shows a structure in which the U-shaped portion of the movable body structure in Figure 1 is filled with 3 f gold of a flexible porous material such as sponge. This is what I did.

〔Effect of the invention〕

According to the present invention, since the contact position of the ball with the moving body moves little by little while the motor is being driven, wear is reduced and the point contact state is maintained for a long time, significantly extending the life of the motor. The amount of rotation of the rotated ball is extremely small, and the resulting drop in motor rotational speed is extremely small, resulting in almost no reduction in motor efficiency.Also, since the vibrating body and the moving body are in contact with each other through a large number of spheres, there is no air film between them. Needless to say, there is no reduction in output due to pinching, and the effect of sweeping away wear particles is good.

[Brief explanation of drawings]

Fig. 1 (,) (b) is a longitudinal cross-sectional view of one embodiment of the present invention and a view taken along AA', Fig. 2 is a diagram showing a nine-point system used for explanation, and Fig. 3 (,) ( b) is a longitudinal cross-sectional view and a cross-sectional view taken along BB' of a movable body according to another embodiment of the present invention, and FIGS. 4 and 5 respectively show movable bodies according to still other different embodiments. 1 is an electro-mechanical energy conversion element, 2 is a vibrating body, 3 is a moving body, 3a is a structure,
3b is an elastic material, 3c is a ball, 3
d is a retainer, 13e is a pin, and 3f is a cleaning member. Figure 1 (b) Broom 2

Claims (1)

[Claims] In a vibration wave motor that frictionally drives a moving body in contact with the vibrating body by a progressive vibration wave generated in a vibrating body in which a plurality of electro-mechanical energy conversion elements are arranged and joined,
The contact portion of the movable body with the vibrating body is composed of a large number of rotatable balls, and the frictional force between the balls and the movable body body is greater than the frictional force between the spheres and the vibrating body. A vibration wave motor characterized by: