JPS59110387A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To obtain a vibration wave motor capable of normally and reversely rotating in a high drive efficiency by bonding a plurality of electrostrictive elements to the outside surface of an annular vibrator formed in a hollow frustoconical shape, applying a frequency voltage to the elements to pressure contact it to the vibrator in a movable unit to frictionally drive the unit. CONSTITUTION:A vibration absorber 4 is mounted on the stepwise difference part of a stationary cylinder 5 to become a base, and an annular metal vibrator 2 bonded with electrostrictive elements 3 is mounted on the absorber 4. A thrust roller bearing 10 which is formed of rollers 9 and a seat 6 is retained by a regulating ring 7 engaged with the cylinder 5 and a spring 8, and a rotor 1 is pressure contacted with the front surface of the vibrator 2. The vibrator 2 is formed in a hollow frustoconical shape, and the elements 3 are bonded to the outside face 2a. The elements 3 are formed of two groups of electrostrictive elements 3a, 3b, which are arranged at 1/2 pitch of the wavelength (lambda) of a vibrating plate. An AC voltage is applied from an AC power source 6a to the elements 3a, and the AC voltage is applied from the power source 6a through a 90 deg. phase unit 6b. In this manner, a vibration wave motor capable of normally and reversely rotating in a high drive efficiency can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a vibration wave motor driven by progressive vibration waves.

As disclosed in, for example, Japanese Unexamined Patent Publication No. 52-29192, a vibration wave motor converts vibrational motion generated when a frequency voltage is applied to an electrostrictive element into rotational motion or -dimensional interlocking motion. Compared to conventional electromagnetic motors, they do not require windings, so they have a simpler and more compact structure, can deliver high torque even when rotating at low speeds, and have the advantage of having a small moment of inertia, so they have been attracting attention recently. .

However, conventionally known vibration wave motors use standing vibration waves generated in a vibrating body to frictionally drive a moving body such as a rotor in one direction when converting vibratory motion into rotational motion. The vibrating body and the moving body come into frictional contact during the forward motion of vibration, and separate during the backward motion. Therefore, the vibrating body and the moving body have a structure in which they contact each other within a minute range,
In other words, the structure must be close to point or line contact, which results in poor friction drive efficiency.

Further, since the driving force acts in a fixed direction, the moving body moves in only one direction. In order to move in the opposite direction, it is necessary to mechanically switch the direction of the vibration force using another vibrator. Therefore, in order to obtain a vibration wave motor capable of forward and reverse rotation, multiple devices are required, and the simplicity and compactness of the structure, which are the characteristics of the vibration wave motor, are halved.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to overcome these drawbacks of conventional vibration wave motors and to provide a vibration wave motor that has a very simple structure, has high drive efficiency, and is capable of forward and reverse rotation.

In order to achieve the above object, the present invention provides a plurality of 'It! , the strain elements 3a and 3b4 are arranged and bonded with a phase difference, and a frequency voltage is applied to each of the electrostrictive elements 3a and 3b to generate a progressive vibration wave in the vibrating body 2, and by the vibration wave, This vibration wave motor is characterized in that a movable body 1 brought into pressure contact with the vibrating body 2 is frictionally driven.

FIG. 1 is a side view of a vibration wave motor to which the present invention is applied, with a cutaway -Δ1.

A vibration absorber 4 made of felt or rubber is attached to the stepped portion of the fixed cylinder 50 that serves as a pace, and an electric current 1r? Take the metal vibrating body 2 to which the element 3 is glued (-J), each of which is designed not to rotate. 7 and spring 8 to press the rotating body 1 against the surface of the vibrating body 2.

FIG. 2 shows a disassembled state of the vibrating body 2 and electrostrictive element 3 of the vibration wave motor having the above structure.

The annular vibrating body 2 made of metal has a hollow truncated cone shape, and a plurality of electrostrictive elements 3 are bonded to its outer surface 2a. The reason why the vibrating body 2t is shaped like this is because it is necessary to minimize the difference between the inner diameter D1 and the outer diameter D2 of the vibrating body 2 as much as possible, and to make the width of the electrostrictive element 3 in the axial direction sufficient. and ensure a sufficient contact area between the vibrating body 2 and the rotating body 1,
This is to obtain high torque. However, the cylindrical shape is not preferable because the mechanism for pressing the rotating body 1 against the vibrating body 2 becomes complicated.

The electrostrictive element 3 includes a plurality of electrostrictive elements 3a and a plurality of electrostrictive elements 3b.
Each of the electrostrictive elements 3a is arranged with a half-pinch of the wavelength of the vibration wave, and the electrostrictive elements 3b are similarly arranged with a half-pinch of the wavelength of the vibration wave. Note that the electrostrictive element 3a
(or 3b) may be made into a single element without arranging a plurality of them, and it may be polarized to the above-mentioned pitch. The mutual pitch between the electrostrictive elements 3a and 3b is (n0+174).
, 2.3...e) A shifted phase difference arrangement is made. Each of the electrostrictive elements 3a has a lead of 3 A l l on the absorber 4 side.
A beam 1 and a wire 11 are connected to each of the electrostrictive elements 3b connected to the
b are connected, each of which has a trace source 6a and a 900 phase 6b.
(See Figure 3). Further, a lead wire 11c is connected to the metal vibrating body 2, and the wires FjQ and 6a are connected to each other.

The operation of the vibration wave motor configured as described above is as follows.

FIG. 3 shows how vibration waves are generated in the motor.

The electrostrictive elements 3a and 3b bonded to the metal vibrating body 2 are
For convenience of explanation, they are shown adjacent to each other, but since the phase shift condition of ``2 entry/4'' is added by l11-, the first
This arrangement is substantially equivalent to the arrangement of electrostrictive elements 3a and 3b of the motor shown in the figure.

``■'' in each of the electrostrictive elements 3a and 3b indicates that the alternating current voltage expands when the cycle is on the positive side, and θ indicates that the voltage is also reduced by 1 during the cycle on the positive side.

The fully flexural vibrating body 2 is made into the upper pole of the centering elements 3a and 3b, and the centering element 3a is connected to the AC power supply 6a by V=V.
An AC voltage of sin ωt is applied to the electrostrictive element 3b, and V with a phase shift of 4 is input from the AC power source 6a through a 900 phase shifter 6b. An AC voltage of sin (ωt±π/2) is applied. The ten or minus sign in the equation is switched by the phase shifter 6b depending on the direction in which the movable body 1 (omitted in this figure) is moved;
When you switch it to the side, the phase shifts +90' and moves in the positive direction.
When switched to the - side, the phase shifts by 190 degrees and moves in the opposite direction.

It is now switched to the negative side, and the electrostrictive element 3b has V=V(,
Assume that a voltage of 5 inches (ωt-π/2) is applied. When the electrostrictive element 3a alone vibrates with the voltage v=v0sinωt, vibrations due to the Anzai wave as shown in FIG.
When vibrating according to i n ((1) tw/2), vibrations due to standing waves as shown in (b) occur. When the above-mentioned two phase-shifted alternating currents are simultaneously applied to each of the central elements 3a and 3a, the vibration waves become progressive. (A) is time t = 2nπ/ω, (B) is t = π/2ω + 2nπ/ω
, (c) is t=π/ω+2nπ/ω, (d) is L=3π
/2ω+2nπ/ω, and the wavefront of the vibration wave travels 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 2 as shown in Fig. It's doing an elliptical motion. , since the moving body 1 is in contact with the surface of the vibrating body 2 and is in contact only with the apex of the vibrating surface, the component of the longitudinal amplitude U of the elliptical motion of the mass point A-A... at the apex is The moving body l moves in the direction of arrow N.

If the phase is shifted by +90° using a 90° phase shifter, the vibration wave will be -
Moving in the X direction, the moving body l moves in the opposite direction to the N direction.

As described above, the vibration wave motor driven by progressive vibration waves can be switched between forward and reverse directions with an extremely simple configuration.

The velocity at the apex of the mass point A is V = 2πfu (f is the frequency), and the moving speed of the moving body I depends on this, and the lateral amplitude W ie, the magnitude of the elliptical motion is proportional to the voltage applied to the electrostrictive element.

Since the frictional drive of the moving body 1 is performed at the apex of the wave surface of the progressive vibration wave of the vibrating body 2, the resonance of the wave surface in the direction of the apex (Z-axis direction in Figure 4) improves the driving efficiency. It is necessary to do so.

Since the vibrating body 2 in the embodiment is annular, it is necessary that the ring diameter of the vibrating body 2 satisfies the relationship: wavelength input - π/nD (n is a natural number). The 6th diameter in the ring is the average diameter of the inner diameter of the ring and the outer diameter D2, and D = (Dl +D
2)/2.

For efficiency, it is necessary to make the difference between the inner diameter and outer diameter D2 of the ring as small as possible in order to achieve resonance.

Therefore, as mentioned above, the vibrating body 2 is shaped like a truncated cone.

As explained above, since the vibration wave motor of the present invention utilizes progressive vibration waves, it can easily be switched between forward and reverse directions by simply changing the timing of shifting the phase of the applied AC voltage. Since the vibrating body 2 has a circular G1 trapezoidal shape, the difference between the inner diameter and the outer diameter of the vibrating body 2 can be reduced while keeping the width of the piezoelectric element 3 wide, and the dynamic effectiveness can be improved. In addition, since the rotating body 1 and the vibrating body 2 come into contact with each other on the circular AL plane, an alignment action occurs that automatically brings the centers of both closer together, resulting in smooth rotation, and the contact area becomes larger, improving rotational efficiency and reducing vibration. (
This can reduce wear and tear.

The above-mentioned vibration wave motor can be used as a driving source for all types of equipment, including driving the aperture, zoom, etc. of lens barrels of still cameras, cine cameras, television cameras, and the like.

[Brief explanation of drawings]

Figure 1 shows an embodiment of a vibration wave motor to which the present invention is applied.
811 notch side view, Figure 2 is an exploded enlarged perspective view of the vibrating body and °6 strain element of the vibration wave motor of the present invention, Figures 3 and 4 are illustrations of the operating principle of the vibration wave motor, and l indicates movement. 2 is a vibrating body, 3 is an Ik strain element, and 4 is a vibration absorber. 'hmm! 3 Figure 4 ;゛... 1;

Claims (1)

[Claims] (1) A plurality of strain elements are arranged and bonded with a phase difference to the outer surface of a hollow truncated cone-shaped annular vibrating body, and a frequency voltage is applied to each of the electrostrictive elements, so that the vibrating body A vibration wave motor, characterized in that a progressive vibration wave is generated, and the vibration wave frictionally drives a moving body that is brought into pressure contact with the vibration body.