JPH01315274A - Piezoelectric motor - Google Patents

Abstract

PURPOSE:To enhance conversion efficiency by dispersively forming a plurality of cutouts circumferentially on the parts of first and second supports of a stator in contact with a rotor. CONSTITUTION:A tuning forklike cross-sectional annular support 21 is composed of a pair of disclike supports 22, 23 so disposed as to be opened toward its outside and opposed to a thicknesswise direction. A stator is composed of the support 21. A first disclike piezoelectric vibration plate 24 adheres to the lower face of the support 22, and a second disclike piezoelectric vibration plate 25 adheres to the upper face of the support 23. A rotor 29 is so provided as to surround the stator, and disclike metal plates 30, 31 are composed by coupling them by an elastic member 32. In this case, a plurality of cutouts 26, 27 are dispersively formed circumferentially on the outer edges (the parts under pressure contact with the rotor 29) of the supports 22, 23. Thus, the moving direction displacements of the supports 22, 23 are amplified, and the cutouts 26, 27 are dispersively formed circumferentially. Accordingly, the parts 26a, 27a disposed therebetween are largely displaced as compared with the bases of the supports 22, 23.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an annular piezoelectric motor that utilizes traveling waves based on solid-state resonance in an ultrasonic band. Regarding improvements.

[Prior Art] FIG. 2 is a partially cutaway perspective view of a conventional piezoelectric motor.
FIG. 3 is a sectional view of essential parts of the piezoelectric motor.

With reference to FIGS. 2 and 3, this piezoelectric motor has the following characteristics:
A stator is constructed using an annular support 1 having a tuning fork-shaped cross section. That is, the first... A second piezoelectric diaphragm 4.5 is attached, and the pressure 1! Vibration plate 4
．． A traveling wave is generated in the circumferential direction of the support 1 by bending and vibrating the support 1 .

1st. In the second piezoelectric diaphragms 4 and 5, a plurality of regions connected in the circumferential direction are decentralized as shown in FIG. That is, in the first piezoelectric diaphragm 4, the ? jl number of polarized regions 7a, and a second
A plurality of decentralized regions 7b and unpolarized regions 7c and 7d are formed to constitute an excitation source. In Figure 4, the + and - symbols enclosed in circles indicate the polarization direction of each polarization region, respectively, with + indicating polarization extending from the top side to the bottom side, and - indicating polarization from the bottom side. Indicates that the top surface is polarized.

As is clear from FIG. 4, the second piezoelectric diaphragm 5 also has a plurality of polarized regions 7a and 7b formed in order to constitute the first and second excitation sources, and also has unpolarized regions. 7c and 7d are arranged between them.

Note that the polarization direction of the polarized region in the second piezoelectric diaphragm 5 is polarized in the opposite direction to that of the corresponding polarized region in the first piezoelectric diaphragm 4. This is the first. This is because by vibrating the second piezoelectric diaphragm 4.5 in an opposite phase, a rotor, which will be described later, is rotated.

Although not particularly illustrated, the first. Appropriate electrodes are formed on both sides of the second piezoelectric diaphragm 4.5 to vibrate each piezoelectric diaphragm 4.5.

Since the piezoelectric diaphragm 4.5 is polarized as shown in FIG. 4, when a voltage is applied to the piezoelectric diaphragm 4.5 to generate a traveling wave,
- The following bending vibrations occur and the support 1 is vibrated as shown schematically in FIG. And the first. By generating traveling waves based on the above-described bending vibration in the second piezoelectric diaphragms 4 and 5, the rotor 11, which is pressed against the support 1, is rotationally driven.

As shown in FIG. Second annular metal plate 12.1
3 are connected by bolts 14. Reference numeral 15 denotes an elastic material, which is provided to adjust the degree of connection between the two metal plates 12 and 13 using bolts 14, thereby adjusting the pressure contact force between the rotor 11 and the support l.

[Technical Problem to be Solved by the Invention] In the piezoelectric motor using the support 1 having a tuning fork cross-sectional shape as described above, the two support parts 2 and 3 arranged above and below are subjected to bending vibration, and The rotor 11 is rotationally driven by the traveling wave based on this.

Therefore, since the rotor 11 is rotated by the drive sources arranged above and below, it has the advantage of excellent rotational efficiency.

However, when the piezoelectric motor shown in FIG. 2 was actually rotated, it was found that it was not necessarily possible to achieve the intended efficiency, that is, high conversion efficiency and high torque.

Therefore, an object of the present invention is to provide a piezoelectric motor that exhibits higher energy conversion efficiency and has high torque.

[Means for solving technical problems]

The piezoelectric motor of the present invention includes an annular support having a tuning fork-shaped cross section and having a pair of disc-shaped support portions facing each other in the thickness direction; , and is supported and vibrates in a bending vibration mode to generate a traveling wave in the circumferential direction of the support. The stator includes a second piezoelectric diaphragm and a second piezoelectric diaphragm.

Also, 1st. A rotor is pressed into contact with the second support portion, and is configured to be rotated by traveling waves caused in the stator.

Then, the first part of the support. A plurality of notches or through holes are formed distributed in the circumferential direction of the second disk-shaped support portion in a portion that comes into contact with the rotor.

[Effect]

The present invention was made based on the fact that the inability to obtain the intended efficiency in conventional annular piezoelectric motors with a tuning fork cross section is caused by slippage between the rotor and stator8. In the present invention, the first . Since a plurality of notches or through holes are formed distributed in the circumferential direction in the second disc-shaped support part in the part that comes into contact with the rotor, the part sandwiched by the notches or through-holes of the disc-shaped support part The displacement in the traveling direction is amplified. At the same time, since the portions sandwiched by the notches or through holes are brought into point contact with the rotor one after another, slippage between the rotor and stator is also reduced.

[Explanation of Examples]

FIG. 1 is a perspective view of a stator portion according to a first embodiment of the present invention, and FIG. 7 is a partial cross-sectional view of a state in which a rotor of the first embodiment is assembled.

Referring to FIGS. 1 and 7, an annular support 21 having a tuning-fork cross section has a pair of disc-shaped supports that are open toward the outside and are arranged to face each other in the thickness direction. 22.23.

A stator is constructed using this supporting body 21 having a tuning fork shape in cross section.

That is, a first disc-shaped piezoelectric diaphragm 24 is disposed on the lower surface of the support portion 22, and a second piezoelectric diaphragm 2 is disposed on the upper surface of the support portion 23.
5 is attached. Note that since the piezoelectric motor of this embodiment utilizes the primary resonance mode of the annular support 21, the piezoelectric diaphragms 24 and 25 are the same as the piezoelectric diaphragms 4 and 25 of the conventional example shown in FIG. It is configured similarly to 5.

The feature of this embodiment is that a plurality of notches 26 and 27 are formed distributed in the circumferential direction on the outer edge of the disc-shaped support portion 2'2, 23, that is, on the portion that will be pressed into contact with the rotor, which will be described later. It lies in being.

Note that 28 indicates a cylindrical bracket for fixing the support body 21.

Returning to FIG. 7, the rotor 29 surrounds the stator.
is provided. The rotor 29 is constructed similarly to the conventional example shown in FIG. That is, a disc-shaped metal plate 30. has annular walls extending in the direction of each other on the outer peripheral edge side.
31 are connected via an elastic material 32.

In the piezoelectric motor of this embodiment, the first. By vibrating the second piezoelectric diaphragm in a bending vibration mode, the support part 22 of the annular support body 21 is
．． 23, a traveling wave is caused. Therefore, the support part 22
．． The rotor 29, which is pressed against the rotor 23, is rotated based on the traveling wave.

However, in this embodiment, FIG. 8(a).

As shown schematically in (b) as seen from the outside, the first
．． When the second piezoelectric diaphragm 24.25 is vibrated, the displacement of the support portion 22.23 in the advancing direction is amplified. That is, since the notches 26 and 27 are formed dispersedly in the circumferential direction,
The portions 26a and 27a sandwiched between the notches 26 and 27 (for ease of understanding, the outer peripheral end faces are shown hatched) are thicker (displacement be done.

Therefore, the portions 26a and 2 sandwiched between the notches 26 and 27
Since the amount of displacement in the advancing direction of 7a is larger than that of the base portions of the support portions 22 and 23, a larger torque is applied to the rotor 29 side.

At the same time, a portion 26a sandwiched between the notches 26 and 27.

Since the portions 27a are formed in a distributed manner in the circumferential direction, the portions 26a
a and 27a are successively pressed against the rotor 29 in a point-contact manner, so that slippage between the stator and rotor is effectively reduced.

Although the above embodiment utilizes the primary resonance mode of the annular elastic body, a similar piezoelectric motor can also be constructed using the secondary resonance mode.

FIG. 9 is a partially sectional perspective view of a second embodiment using a secondary resonance mode, with the rotor removed, and FIG. 1O is a sectional view of a main part of the second embodiment.

When the secondary resonance mode is used, the support 4I is subjected to bending vibration as schematically shown in FIG.

Therefore, as shown in FIG. 10, fixing parts 42 and 43 for fixing the stator to a bracket (not shown) are provided above and below the tuning fork-shaped support 41.

Further, as shown in FIG. 6, the support body 41 having a tuning-fork cross-sectional shape is displaced most in the radial center region of the disk-shaped support portions 44 and 45.

Therefore, in this embodiment, a plurality of through holes 46, 47 are formed distributed in the circumferential direction in the radially central region of the support portion 44, 45. The rest of the structure is the same as that of the first embodiment, so the description of corresponding parts will be omitted by assigning corresponding reference numbers.

In the second embodiment, a plurality of through holes 46 , 47 are formed distributed in the circumferential direction in the central region of the support portion 44 , 45 , that is, in the portion pressed against the rotor 48 . The portions 46a, 47a sandwiched by the notches 47 are the portions 26a, 27a sandwiched by the notches 26, 27 of the first embodiment.
Similar to 7a, it is largely displaced in the traveling direction. That is,
Since the amount of displacement of the portions 46a, 47a sandwiched between the through holes 46.41 is larger than that of the support portions 44.45 themselves, the rotational efficiency of the rotor is effectively increased.

In addition, the portions 46a and 47 sandwiched between the through holes 46 and 47
Since the points a contact the rotor in a point-to-point manner, slippage between the rotor and stator is also reduced.

It goes without saying that when the secondary resonance mode is used as in this embodiment, it is necessary to decentralize the piezoelectric diaphragms 44a and 45a so that secondary resonance is likely to occur.

1st. In the second embodiment, the driving force was transmitted to the rotor using the outer main surfaces of the support parts 22, 23, and 44.45 of the support body 21.41, but the inner surface of the support parts The motor may be configured to rotate by arranging a rotor.

FIG. 11 shows a third embodiment in which the rotor is arranged between such supports.

As is clear from FIG. 11, in the piezoelectric motor using the secondary resonance mode, the support 41 constituting the stator
The first . Second piezoelectric diaphragms 44a and 45a are attached.

This is because the inner main surfaces of the support portions 44 and 45 are brought into pressure contact with the rotor 48.

Similar to the second embodiment, a plurality of through holes 46 and 47 are formed in the support portions 44 and 45 in a distributed manner in the circumferential direction. On the other hand, the rotor 4B is inserted and arranged in the space between the support parts 44 and 45, and is constituted by a metal ring having a U-shaped cross section. Reference numeral 49 denotes an elastic material, which is provided to adjust the degree of repulsion between the driven parts 48a and 48b of the rotor 48, thereby adjusting the pressing force with the parts sandwiched between the through holes 46 and 47.

Also in the embodiment shown in FIG.
．． 47 are distributed in the circumferential direction, so that the through holes 4
6. Part 46a sandwiched by 47.

47a, the first. Similar to the second embodiment, the amount of displacement in the traveling direction is amplified.

〔Effect of the invention〕

As described above, according to the present invention, the first and second
Since a plurality of notches or through holes are distributed in the circumferential direction in the portion of the support portion that comes into contact with the rotor, the amount of displacement in the traveling direction is amplified in the portion sandwiched by the notches or through holes. . Therefore, the conversion efficiency of the annular piezoelectric motor using the support body having a tuning fork shape in cross section can be effectively increased.

Similarly, since the portions sandwiched by the notches or through holes are successively brought into point contact with the rotor, slippage between the rotor and stator is also reduced.

Therefore, it is possible to realize a high torque annular piezoelectric motor.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional perspective view for explaining the stator portion of the first embodiment of the present invention, FIG. 2 is a partial cross-sectional perspective view of a conventional piezoelectric motor, and FIG. 3 is a cross-sectional view of a conventional piezoelectric motor. ,
Figure 4 is a perspective view for explaining the polarization state of the piezoelectric diaphragm, Figure 5 is a schematic diagram for explaining the bent state of the stator when using the primary resonance mode, and Figure 6 is for the secondary resonance mode. FIG. 7 is a sectional view of the fourth embodiment, and FIG. 8 (a
) and (b) are schematic cross-sectional views for explaining the functions of the notches in the first embodiment, FIG. 9 is a partial cross-sectional perspective view showing the stator portion of the second embodiment of the present invention, and FIG. The figure is a sectional view of the second embodiment, and FIG. 11 is a sectional view of the third embodiment of the present invention. In the figure, 21 is an annular support body, 22 and 23 are the first
．． Second support part, 24.25 is a piezoelectric diaphragm, 26.27
26a and 27a are portions sandwiched between the notches, and 29 is a rotor. 1 z Figure 7 1 ” 27 Ka 31 Figure 2 Figure 5 No. 6 ♂ I+4 - ゝヰ5 Figure 8 @ Figure 9

Claims (1)

[Scope of Claims] An annular support member having a tuning fork-shaped cross section and having a pair of disc-shaped support parts that are open to face each other in the thickness direction, and a main surface of each of the pair of support parts of the support member, a stator having first and second piezoelectric diaphragms that are supported and vibrated in a bending vibration mode to generate traveling waves in the circumferential direction of the support; and first and second supports for the stator. It is pressed against the
A piezoelectric motor comprising a rotor rotated by a traveling wave caused in the stator, wherein the first and second disc-shaped support parts of the support body have a plurality of notches or penetrations in a portion that comes into contact with the rotor. A piezoelectric motor characterized in that holes are formed distributed in a circumferential direction.