JPH0232771A - Traveling-wave motor - Google Patents

Abstract

PURPOSE:To simplify the structure of an apparatus and to improve the efficiency thereof by using a thin plate in the elastic body of a laminated type piezoelectric material actuator. CONSTITUTION:A plurality of laminated type piezoelectric material actuators 61 to 68 laminating a plurality of piezoelectric ceramics are arranged on the whole peripheral face of an elastic body 1. A metal sheet is used as said elastic body 1 and a rotator 2 is brought into contact therewith. Respective actuators 61 to 68 are arranged through adhering between a fixed support base 7 and the elastic body 1. Also, alternate actuators 61 to 64 out of respective actuators 61 to 68 are designated as A-phase and these actuators 61 to 68, as B-phase. Thus, said A- and B-phase are supplied with driving signals S1, S0 having a phase difference of 90 deg. to generate a progressive wave in the elastic body 1 and to turn the rotator 2. Said rotator 2 is pressurized from above by a spring, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a traveling wave motor in which a rotor is driven by traveling waves generated in an elastic body.

[Summary of the invention]

The present invention arranges a plurality of laminated piezoelectric actuators around the entire circumferential surface of a ring-shaped elastic body. This is shown in principle.

In FIGS. 4 and 5, a ring-shaped rotor 2 is attached to one surface of a ring-shaped elastic body 1 made of metal or the like.
is in contact with the piezoelectric material 3 such as piezoelectric ceramic on the other surface.
1 to 310 are glued together.

In addition, each piezoelectric body 3. The symbol - attached to ~3111 indicates the polarization direction in the thickness direction.

Piezoelectric bodies 31-3. , which forms a human figure, is made up of one pair with a ten piezoelectric body and a negative piezoelectric body in one cycle, and in the illustrated example, 2.5 pairs are provided.

The length λ of one period is selected to be equal to the wavelength λ of the drive signal S0. The piezoelectric bodies 36 to Lo form the B phase and are configured in the same manner as the above A phase.

Further, the A phase and the B phase are arranged with a mechanical phase difference of Aλ from each other.

In the above configuration, a drive signal S0 having a resonance frequency of the elastic body 1 determined by the wavelength λ is applied from the drive signal source 4 to the B-phase piezoelectric bodies 36 to 31°, and this drive signal S0 is applied to the phase shifter 5. A drive signal Sl whose phase is shifted by 90'' is applied to the A-phase piezoelectric bodies 3. to 3. As a result, the wavelength λ as shown by the solid line in FIG. A vibration having a phase difference of 2λ from the vibration vibration is generated.This vibration causes the rotor 2 to rotate on the elastic body l.

Moreover, if the drive signals S0 and S are replaced, A in FIG.
The phase relationship between the phase vibration and the B-phase vibration is reversed, and the rotation direction of the rotor 2 is reversed.

[Problem to be solved by the invention]

The conventional traveling wave motor described above has the following drawbacks.

(1) Since the elastic body 1 made of metal is vibrated at its resonant frequency, it is easily affected by internal loss.

(2) The piezoelectric body 3 is bonded to the elastic body 1 using an adhesive, but the strength of this adhesive is generally weak in the shear direction, and the piezoelectric body generates distortion in the shear direction, which tends to cause loss. .

(3) The elastic body l vibrates due to bending vibration, but in that case,
As shown in FIG. 7, the bending vibration causes expansion and contraction strain on the surface of the elastic body 1, and this expansion and contraction strain is not uniform. on the other hand,
In the case of a single piezoelectric material, the expansion and contraction strain is uniform (1).The difference in strain in both cases is t.

(4) As shown in Fig. 7, the amplitude δ of the elastic body 1 is obtained by the distortion of the piezoelectric body, so it is an indirect method, and therefore the load is reduced on the piezoelectric body, resulting in a large output. is difficult to obtain.

(5) In an actual traveling wave motor, the elastic body 1 is fixedly supported, but this fixed portion hinders vibration, which tends to result in loss.

(6) When applied to an actual device such as a camera lens barrel, the structure becomes complicated and costs increase.

[Means to solve the problem]

In the present invention, a plurality of laminated piezoelectric actuators are arranged around the entire circumferential surface of a ring-shaped elastic body.

[Effect]

By driving the expansion and contraction directions of adjacent laminated piezoelectric actuators in directions opposite to each other, vibrations necessary for rotation of the rotating body can be obtained.

〔Example〕

As shown in FIGS. 1 and 2, the present invention provides a plurality of laminated piezoelectric actuators 6I to 6. are arranged on the entire circumferential surface of the elastic body 1. As shown in the figure, the elastic body 1 is made of a thin metal plate, and the rotating body 2 is in contact with this thin plate-like elastic body 1. Each of the actuators 61 to 6[l is bonded and arranged between the fixed support base 7 and the elastic body 1. In addition, every other actuator 61 to 64 of each actuator 6 to 68 is set to the A phase, and these actuators 6
Actuators 65 to 66 arranged at intervals of 2λ between □ and 64 are designated as B phase. These A phase and B
Drive signals S+ and So having a phase difference of 906 as in FIG. 4 are supplied to the phases. Thus, when one of the adjacent actuators is extended, the other actuator is retracted.

According to the above configuration, each of the A-phase and B-phase actuators 6
By driving the actuators 1 to 68, an amplitude δ is generated in the elastic body 1 as shown in FIG. 1, whereby each actuator expands and contracts to generate a traveling wave, and the rotating body 2 rotates. It is assumed that the rotating body 2 is pressurized from above by springs or the like.

In the case of the traveling wave motor according to the present invention, it is necessary to provide n actuators 61 to 61 over the entire circumferential surface of the elastic body 1. Furthermore, four actuators are required to create one crest of a wave generated in the elastic body 1. Further, it is not necessary to vibrate the elastic body 1 at a resonant frequency as in the conventional case. If a thick metal plate is used for the elastic body 1, its rigidity will actually hinder the generation of vibrations, so a thin metal plate with a smooth and uniform surface is used as the elastic body 1.

FIG. 3 shows another embodiment of the present invention, in which an elastic body 1 is provided with comb teeth 8 made of a rigid metal body, and a rotating body 2 is brought into contact with the comb teeth 8 via a slider 9. .

In the embodiment shown in FIG. 1 described above, since a thin plate is used as the elastic body 1, the elliptical motion generated by the expansion and contraction of the actuator may be difficult to be transmitted to the rotating body 2. In such a case, the elliptical motion is magnified by the comb teeth 8 and transmitted to the rotating body 2, which is more efficient.

〔Effect of the invention] According to the present invention, the following effects can be obtained.

(1) By using the FIV plate as the elastic body, the influence of internal loss due to the material of this thin plate is extremely small, and the performance of the laminated piezoelectric actuator can be fully utilized.

and is not easily affected by adhesives.

(3) Since the displacement of the actuator section becomes the displacement of its traveling wave, displacement is easily obtained.

(4) Since the behavior is limited to one direction, there is no influence of fixed support parts such as support bases, and the structure is simplified.

(5) The entire motor can be easily formed into a ring shape.

(6) Since reflected waves are not generated, a linear type can also be used.

(7) Since the resonance frequency of the elastic body is not used, the driving frequency can be freely set depending on the application, and therefore the elastic body can be made into various shapes to expand the field of application.

[Brief explanation of the drawing]

1 and 2 show embodiments of the present invention.
The figure is a side view of the main part, Fig. 2 is a plan view, Fig. 3 is a side view of the main part showing another embodiment, Fig. 4 is a plan view showing the principle of a conventional traveling wave motor, and Fig. 5 is a side view of FIG. 4, FIG. 6 is a vibration waveform diagram, and FIG. 7 is a side view showing the state of vibration of a conventional traveling wave motor. In addition, in the symbols used in the drawings, 1--...-- Ring-shaped elastic body 6I~
64.--Laminated piezoelectric actuators 6, 6 to 6 e'-' laminated piezoelectric actuators constituting A phase.

Claims (1)

[Claims] A progression characterized in that a plurality of laminated piezoelectric actuators are arranged around the entire circumferential surface of a ring-shaped elastic body, and the expansion and contraction directions of adjacent laminated piezoelectric actuators are opposite to each other. wave motor.