JPH082186B2 - Vibration wave motor - Google Patents

Description

TECHNICAL FIELD The present invention relates to the structure of a vibration wave motor, and more particularly, to a structure of a traveling wave ring motor that drives a rotor by a traveling wave.

(Prior Art) A vibration wave ring motor for frictionally driving a moving body that is brought into pressure contact with the vibrating body by applying a voltage to an electrostrictive element bonded to the vibrating body and applying frictional vibration to the vibrating body Akira
It is known by 57-206299 (Japanese Patent Publication No. 5-14510).

First, such a ring motor will be described. First
In the figure, reference numeral 1 is an electrostrictive element such as PZT (lead zirconate titanate), which is joined to a vibrating body 2 made of a ring-shaped elastic plate as shown in FIG. 2 and held by a fixed body (not shown). It constitutes the stator. A movable body 3 is rotatably held by the fixed body and is a moving body which is in pressure contact with the vibrating body 2 to form a rotor. Reference numeral 4 is a vibration absorbing material inserted between the fixed body and the vibrating body 2.

A plurality of electrostrictive positions are joined, and the other group is arranged by a pitch shifted by 1/4 wavelength of the vibration wave with respect to one group. The electrostrictive elements in the group are pitches of ½ wavelength and are arranged so that the polarities of adjacent ones are opposite.

One AC voltage electrostrictive element V _O sin (.omega.T) groups in total of the vibration wave motor having such a structure is applied, to apply an AC voltage of V _O cos (.omega.T) in the other group within the whole of electrostrictive elements. Therefore, each electrostrictive element has a polarity opposite to each other,
The two groups vibrate when an alternating voltage with a 90 ° phase shift is applied between them. When this vibration is transmitted, the vibrating body 2 becomes the electrostrictive element 1
Bending vibration according to the arrangement pitch. When the vibrating body 2 travels at the position of every other electrostrictive element, the position of every other electrostrictive element retracts.

On the other hand, as described above, one group of electrostrictive elements is
Bending vibration progresses because of the position shifted by 1/4 wavelength. While the AC voltage is being applied, vibrations are excited one after another to form a progressive bending vibration wave and propagate through the vibrating body 2.

The wave traveling state at this time is shown in FIGS. 3 (a), (b) and (c).
It shows in (d). It is assumed that the progressive bending vibration wave advances in the direction of arrow X. When O is the center plane of the vibrating body in the stationary state, the center plane 0 is in the state of the chain line 6 in the vibrating state, and the stress due to bending antagonizes this center plane 6 (note that the stress due to this bending antagonizes). The surface is referred to below as the neutral surface). Looking at the cross section 7 orthogonal to the neutral plane, no stress is applied at the line 5 of intersection between these two planes, and only the vertical vibration occurs. At the same time, the cross section 7 oscillates from the cross line 5 to the left and right. In the state shown in FIG. 7A, a point P on the line of intersection between the cross section 7 and the surface of the vibrating body 2 on the moving body side is the right dead point of the left and right vibration, and only the upward movement is performed. This pendulum vibration is stressed in the left direction (the direction opposite to the wave progression) on the positive side (when it is above the center plane O) of the five waves of intersection,
On the negative side of the wave (when it is also on the lower side), rightward stress is applied. That is, in the figure (a), stress F'is applied to the point P'when the line of intersection 5'and the cross section 7'is the former, and point P "when the line of intersection 5" and the cross section 7 "is the latter. Is subjected to stress F ″. When the wave progresses and the intersection line 5 comes to the positive side of the wave as shown in (b), the point P moves leftward and at the same time moves upward. In (c), the point P is the top dead center of the vertical vibration and only moves to the left. In (d), a leftward motion and a downward motion are performed. The wave further progresses, and then returns to the state of (a) through rightward and downward movements, rightward and upward movements. When this series of motions is combined, the point P has a spheroidal motion, and its radius of rotation is a function of t / 2 where t is the plate thickness of the vibrating body. On the other hand, as shown in FIG. 6C, at the point where the point P contacts the moving body 3, the moving body 3 is frictionally driven in the X ′ direction by the movement of the point P.

Similarly to the upper surface, the lower surface of the vibrating body 2 also makes an elliptic motion accompanied by a horizontal motion, and as described above, a large energy loss occurs due to the friction with the absorber fixed to the fixed body.

(Summary of the Invention) The present invention is intended to reduce the energy loss due to the friction between the vibrating body and the absorber as described above, and to improve the efficiency of the motor. In the neutral plane, attention is paid only to vertical vibration and no horizontal vibration, and the neutral plane is configured to support the vibrating body.

(Example) An example is described below with reference to the drawings.

4 to 6 are longitudinal sectional views showing an embodiment of a traveling wave ring motor according to the present invention, respectively, which are constructed in substantially the same manner as in FIG. 3, and corresponding members are designated by the same reference numerals.

In FIG. 4, the ring-shaped diaphragm 2 is configured such that the lower part is scraped off from the center of the plate thickness in the vicinity of the inner periphery thereof, and the neutral surface is supported on a fixed body (not shown) by an absorber. Since the vertical amplitude of the vibrating body is smaller on the inner peripheral side, supporting loss can be minimized by supporting the vibrating body on the center plane near the inner peripheral side.

FIG. 5 shows a structure in which a step is provided near the outer periphery of the diaphragm 2 to support the neutral surface, and it has an advantage that it is easy to mount by utilizing the annular structure which is a characteristic of the ring motor.

FIG. 6 shows a structure in which a brim is projected on the outer periphery of the diaphragm 2 and the lower surface thereof is supported by an absorber.

By supporting the vibrating body with the brim in this way, it is possible to absorb the vertical vibration of the vibrating body by utilizing the spring property of the brim itself and to increase the area of the electrostrictive element, so that a large output can be obtained. Suitable to get. The collar may be configured to project not only on the outer circumference but on the inner circumference.

(Effect of the invention) According to the present invention, since the vibration absorber is supported on the neutral surface by contacting the vibration absorber on the upper surface of the stepped portion provided on the vibrator as described above, Not only can the energy loss due to friction be reduced, but the entire upper surface of the vibrating body can be used as the contact portion of the contact body (moving body).
A sufficient contact area can be taken, the degree of freedom in design is increased, and it is also advantageous for wear.

[Brief description of drawings]

1 to 3 show a conventional example, FIG. 1 is a longitudinal sectional view of a vibration wave motor, FIG. 2 is a perspective view showing the shape of the main part of the vibration wave motor, FIG. 3 (a), (B), (c),
(D) is a diagram for explaining the driving principle of the vibration wave motor, and FIGS. 4, 5, and 6 are sectional views showing the respective embodiments. 1: electrostrictive element, 2: vibrating body, 3: rotor, 4: absorber

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-213286 (JP, A) JP-A-55-17411 (JP, A) JP-B-59-20230 (JP, B2)

Claims (1)

[Claims] 1. A vibration wave motor having a vibrating body for generating a traveling wave and a vibration absorbing material for supporting the vibrating body, wherein the vibrating body is formed on an upper surface and a lower surface side to which a contact body is pressed. And having a step portion along the traveling direction of the traveling wave, with the neutral surface as an upper surface, and the absorber supports the vibrating body by contacting the upper surface of the step portion. Vibration wave motor.