JPS61262091A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To secure a vibrator to an accurate position without adverse influence to the vibration of the vibrator by setting the length of supporting pins for supporting the vibration for a motor and the interval of the pins to have prescribed relationships. CONSTITUTION:A stationary cover 2 is secured with screws 1 to a stationary unit 10. A rotational shaft 5 and a movable body 6 are contacted under pressure with a vibrator 21 by a spring 3 through a thrust bearing 4. A piezoelectric element 8 is bonded to the vibrator 21, and the vibrator 21 is secured by supporting pins 23 to a stationary ring 22. The pins 23 are provided at an interval of integer number times of 1/2 wavelength of a traveling vibration wave generated at the vibrator 21, and the length of the pins 23 is determined so that the vibrator 21 and the pins 23 are vibrated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a vibration wave motor driven by progressive vibration waves.゛〈Prior Art〉 As disclosed in the description of the prior art in JP-A-60-13481, for example, a vibration wave motor utilizes the vibration motion generated when a frequency voltage is applied to a piezoelectric vibrator for driving. Compared to conventional electromagnetic motors, they do not require windings, so they have the advantage of being simpler and smaller in size, and can provide high torque even when rotating at low speeds, and have attracted attention in recent years.

As a means for exciting vibrations in the vibrating body, an electro-mechanical energy conversion element that periodically deforms, such as a piezoelectric element, an electrostrictive element, and a magnetostrictive element, may be used, but for the sake of simplicity, a piezoelectric element will be explained below.

Conventionally, vibration wave motors frictionally drive a moving body by the vibrations of a vibrating body, and therefore are usually used by causing the vibrating body to resonate in a desired vibration mode so as to generate large vibrations in the vibrating body.

In this case, the vibrating body is supported using a vibration absorbing material such as felt so that the vibrations generated in the vibrating body are not transmitted to other components of the motor, but accurate positioning is difficult. Impossible.

There were also problems with durability and maintenance. In addition, in order to drive a moving wave motor efficiently, it is generally necessary to bring the vibrating body and the moving body into pressure contact with a large force.
This support method has the drawback that the loss of support due to pressurization increases as the pressurization force increases.

Regarding the method of supporting this vibrating body, as an improvement to the support method using a vibration absorbing material as described above, the present applicant proposed a method of using a bending vibrator of a holding body such as a pin and supporting it at the antinode of the vibration. (Special No. 58-200371).

However, it has been confirmed through experiments that depending on the length of the pins and the gap between the pins, the vibrations of the vibrating body may be adversely affected and progressive vibration waves may not be efficiently generated.

(Objective of the Invention) The present invention solves the conventional drawbacks by supporting the vibrating body of a vibration wave motor accurately and efficiently, and in a manner that does not adversely affect the vibration of the vibrating body. The purpose is to provide a vibration wave motor.

<Embodiment> FIG. 1 is an exploded perspective view showing the configuration of a vibration wave motor according to an embodiment of the present invention, FIG. 2 is a sectional view thereof, and FIG. 3 is an enlarged view of the vicinity of a vibrating body.

In FIGS. 1 to 3, 1 is a screw 1 that fixes the fixed cover 2 to the fixed body 10, and 3 is a rotary shaft 5 and a movable body 6 connected to the rotary shaft 5 via a thrust bearing 4. This is a spring that brings the vibrator into pressure contact with the vibrating body 21. Note that the vibrating body 21 is an elastic body mainly made of metal, and the piezoelectric element 8 is bonded thereto. 23 is a support pin for fixing the vibrating body 21 to the fixing ring 22, and is shown three times in the figure. Further, one of the support pins 23 is attached to the neutral axis position of the vibrating body 21 by adhesive, and the other is attached to the fixing ring 22.

Here, as a first example, the vibrating body 21 and the support pin 23
The length intersection of the support pins 23 is determined so that the support pins 23 vibrate. In this case, the support pin gap δ is assumed to be the wavelength of the progressive vibration wave generated in the vibrating body 21.

It has been determined to satisfy the following. This was found experimentally.

At this time, the length of the support pin 23 is determined by the following equation, and the joint between the support pin 23 and the vibrating body 21 causes a bending vibration that becomes the antinode of vibration.

α---Constant number (2,3B5,5.498,8.839
-----)ω---Resonance angular vibration wave of elastic body 21However, r---m-Secondary moment of area A of support pin 23
---When the cross-sectional area of the support pin 23 is E-11 and the Young's modulus length of the support pin 23, the pin bonding portion 27 acts as a discontinuous point of vibration, and slight processing of the pin bonding portion 27 With an error of A
The resonance points of the phase and B-phase standing waves will shift, that is, it will not be possible to properly generate progressive vibration waves.

In the embodiment shown in FIG. 2, as shown by a dashed line 25 in FIG.
Letting the wavelength of the progressive vibration wave generated in the vibrating body 21 be, the following is satisfied. This was found experimentally.

When the spacing between the support pins 23 satisfies (3), the length of the support pins 23 must not be set to a length that resonates with the vibration of the vibrating body 21. 2
If the length is set to resonate with the vibration of 1, the vibrating body 21 receives the vibration of the support pin 23 strongly, and the phase of the vibration at the joint between the support pin and the vibrating body does not match (from equation (3)), so the process progresses smoothly. Sexual vibration waves no longer occur.

Also, if the spacing between the support pins 23 satisfies (3), the third
As shown by the dashed line in the figure, the amplitude of the vibration at the joint between the support pin 23 and the vibrating body 21 may become slightly smaller;
Progressive vibration waves can be successfully generated.

In Fig. 3, the dotted line indicating the state of vibration of the support pin is shown as a straight line, but this is different from the amplitude when the support pin resonates as shown by the dotted line in the first embodiment. This is for the purpose of comparison, and although the amplitude is small, it actually vibrates in the same way as in the first embodiment.

The relationship between the spacing of the support pins and the length of the support pins explained above holds true not only when the pins are three-shaped, as shown in FIGS. The pin is not limited to a cylindrical shape as shown in the figure, but may have another cross-sectional shape, such as a flat plate.Furthermore, in this embodiment, the support pin is linear, but the support pin may be L-shaped or other. It may also have a bent shape.

Further, power may be supplied to the piezoelectric element 8 joined to the vibrating body 21 via the support pin.

Furthermore, although this embodiment has been described using a rotary motor, the same applies to a linear motor.

<Effects of the Invention> As explained above, according to the present invention, when supporting a vibration wave motor, the length of the support pin supporting the vibrating body of the motor and the gap between the support pins are set in a predetermined relationship. By doing so, the vibrating body can be fixed at an accurate position without adversely affecting the vibration of the vibrating body, and support loss due to pressurization is also reduced.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing the structure of an embodiment of the present invention, FIG. 2 is a sectional view thereof, and FIG. 3 is an enlarged view of the vibrating body 21 and the vicinity of a support pin that supports the vibrating body 21. . 6 is a moving body, 8 is a piezoelectric element, 21 is a vibrating body, 22 is a fixed body, and 23 is a support pin.

Claims (2)

[Claims] (1) Generating progressive vibration waves in a vibrating body including an electro-mechanical energy conversion element that periodically deforms in accordance with a frequency voltage, and driving a moving body brought into contact with the vibrating body by the progressive vibration waves. In the vibration wave motor, support pins supporting the vibrating body at the connecting portion are provided at intervals of an integral multiple of 1/2 wavelength of the progressive vibration wave, and the support pins are arranged at a frequency of the progressive vibration wave, A vibration wave motor characterized in that the connecting portion has a length that resonates so as to form an antinode of vibration. (2) Generating progressive vibration waves in a vibrating body including an electro-mechanical energy conversion element that periodically deforms in accordance with a frequency voltage, and driving a moving body brought into contact with the vibrating body by the progressive vibration waves. In the vibration wave motor, support pins that support the vibrating body at the connecting portion are provided at intervals other than an integral multiple of 1/2 wavelength of the progressive vibration wave, and the length of the support pins is set to be equal to the length of the progressive vibration wave. A vibration wave motor characterized in that the length of the connecting portion is such that the connecting portion does not resonate at the frequency of vibration.