JPH0795776A - Wave circulating type actuator - Google Patents

Abstract

PURPOSE:To provide a wave circulating type actuator having a high driving efficiency without requiring any feedback passage except a driving section. CONSTITUTION:A wave circulating type actuator composed of a bar-shaped vibrating body 1, piezoelectric body 2, and traveling body 3. Since the actuator has no feedback passage except a driving section, the body 1 has reflecting sections at both ends to reflect waves oscillating in the length direction. In order to improve the driving efficiency of the actuator, in addition, the cross section of the body 1 is formed in such a way that the natural vibration of the body 1 in the direction perpendicular to the first surface group can become almost equal to that in the direction perpendicular to the second surface group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator for circulating a wave in a rod-shaped vibrating body and moving the moving body by the wave.

[0002]

2. Description of the Related Art As a conventional device of this type, there has been one disclosed in, for example, JP-A-59-122385. There
An annular type, a vibration feedback type, an energy feedback type and the like as shown in FIGS. 12 to 14 are disclosed. Annular ultrasonic motor (Fig. 1
2) includes an elastic body 8c, a piezoelectric body 2c, and a moving body 30a. Since the elastic body 8c has an endless structure, surface waves circulate. The moving body 30a is the elastic body 8
The bending vibration generated by the piezoelectric body 2c bonded to the
c is converted into a surface wave and driven.

The vibration feedback type ultrasonic motor (see FIG. 13A) has elastic bodies 8a, 8b, a piezoelectric body 2a, a connector 9a,
9b and the moving body 30b. The elastic body 8b converts the bending vibration generated by the piezoelectric body 2a adhered thereto into a surface wave, and the surface wave is the connector 9a, the elastic body 8a, and the connector 9a.
It propagates in order to b and returns to the elastic body 8b. Moving body 30
b is driven by the surface wave generated on the elastic body 8a.

The vibration feedback type ultrasonic motor (see FIG. 13B) has elastic bodies 8a and 8b, a piezoelectric body 2b and a resonator 11.
It is composed of a, 11b and a moving body 30c. Elastic body 8
b converts the bending vibration generated by the piezoelectric body 2b adhered to it into a surface wave, which is generated by the resonator 11a, the elastic body 8a,
It is sequentially propagated to the resonator 11b and returned to the elastic body 8b.
The moving body 30c is driven by the surface wave generated on the elastic body 8a.

The energy absorbing ultrasonic motor (see FIG. 14) includes an elastic body 8d, vibrators 12a and 12b, and a moving body 3.
It is composed of 0d. The first vibrator serves as a vibration source, and the second vibrator serves as an energy absorber. The vibration generated by the vibration source propagates through the elastic body 8d and the vibrator 12 on the energy absorber side.
It is converted into electric energy by b, and the electric energy is returned to the vibrator 12a. The moving body 30d is driven by the surface wave generated on the elastic body 8d.

[0006]

However, in the above-mentioned conventional devices, there is a problem in that the size of the entire device becomes large because a return path is required separately from the drive section. It was Therefore, an object of the present invention is to provide an actuator that does not require a return path outside the drive section and has high drive efficiency.

[0007]

In order to achieve the above object, a wave circulation type actuator of the present invention (FIGS. 1 and 9) is used.
(Refer to) is a rod-shaped vibration having the first and second surface groups in the longitudinal direction, which are a first surface group composed of two opposed surfaces and a second surface group composed of two opposed surfaces different from the first surface group. A body (1 in FIG. 1 and 10 in FIG. 9) and an electro-mechanical conversion element (2 in FIG. 1 and FIG. 1) provided in the second surface group of the rod-shaped vibrating body for generating waves traveling in the longitudinal direction. 9) 2), and a first reflecting portion (E surface, F surface) for reflecting the wave traveling in the longitudinal direction of the second surface group provided at both ends of the rod-shaped vibrating body and transmitting it to the first surface group.
And a second reflection part (G surface, H) for reflecting the waves transmitted to the first surface group and propagating in the longitudinal direction to circulate in the second surface group.
Surface) and a moving body (3 in FIG. 1 and 3 in FIG. 9) that is pressed against the rod-shaped vibrating body and moves by the traveling wave. Then, the wave circulation type actuator makes the natural frequency of vibration in the direction orthogonal to the surface of the first surface group and the natural frequency of vibration in the direction orthogonal to the surface of the second surface group substantially the same. Characterize.

[0008]

In the present invention, as described above, the natural frequency of the vibration in the direction orthogonal to the surface of the first surface group and the vibration in the direction orthogonal to the surface of the second surface group having the electromechanical conversion element. Since the wave circulation type actuator is configured such that the natural frequencies of the wave circulation type actuator are substantially the same, the drive efficiency of the wave circulation type actuator is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A wave circulation type actuator which is a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a wave circulation type actuator.

FIG. 2 is an explanatory view of a method of supporting the wave circulation type actuator. FIG. 3 is a detailed view of the rod-shaped vibrating body 1 of FIG. FIG. 4 is an explanatory diagram of circulation of bending waves traveling in the rod-shaped vibrating body 1. FIG. 5 is an explanatory diagram of the circulation of surface waves traveling in the rod-shaped vibrating body 1. FIG. 6 is a developed view of the surface of the rod-shaped vibrating body 1.

FIG. 7 is an explanatory view of the structure of the electro-mechanical conversion element 2 and the method of applying power. FIG. 8 is a sectional view of a wave circulation type actuator. The structure of the wave circulation type actuator will be described. The wave circulation type actuator includes a rod-shaped elastic body 1, an electro-mechanical conversion element 2 including a plurality of plate-shaped piezoelectric bodies, a moving body 3, and support members 4 and 5.

The rod-shaped vibrating body 1 has four surfaces A to D in the longitudinal direction, and the surfaces A and C face each other to form a first surface group, and the surfaces B and D face each other to form a second surface. It constitutes a surface group. Further, for convenience of explanation of the traveling direction of the wave, the left end in the longitudinal direction will be referred to as "N end" and the right end will be referred to as "S end" hereinafter. Details of the shape will be described later with reference to FIG. The electromechanical conversion element 2 is composed of a plurality of plate-shaped piezoelectric bodies. Details will be described later with reference to FIG. 7.

The moving body 3 has a U-shaped moving body 3a which comes into pressure contact with the longitudinal right surface portion (B surface in FIGS. 1 and 9) of the rod-shaped elastic body 1 and the longitudinal left surface portion of the rod-shaped elastic body 1 ( 1 and 9
And a U-shaped moving body 3b that comes into pressure contact with the middle D surface). The moving bodies 3a and 3b are coupled by urging members 3c, 3d, 3e and 3f (3e and 3f are not shown) so as to sandwich the rod-shaped elastic body 1 (see FIG. 8).

The support member 4 is connected to the N end of the rod-shaped vibrating body 1 and has a thin rod shape extending in the longitudinal direction of the rod-shaped vibrating body 1 to support the rod-shaped vibrating body 1. The support member 5 is also connected to the S end of the rod-shaped vibrating body 1 and supports the rod-shaped vibrating body 1 in the shape of a thin rod extending in the longitudinal direction of the rod-shaped vibrating body 1. Only one of these two support members may be provided.

The operation of the wave circulation type actuator will be described. The supporting method will be described with reference to FIG. Support members 4, 5
Are arranged between the rod-shaped vibrating body 1 and the fixed portions 6 and 7, respectively, and have a vibration-proof function of preventing the vibration of the rod-shaped vibrating body 1 from propagating to the fixed portions 6 and 7. The vibration generated in the rod-shaped vibrating body 1 vibrates in the direction perpendicular to the longitudinal direction, and because of the surface wave, the total length in the longitudinal direction does not change with time. Therefore, supporting with a thin rod-shaped support member is unlikely to displace in the longitudinal direction and is likely to displace in the direction perpendicular thereto. In order to improve the reflection efficiency of the support member (see FIG. 2 (b)), the length X of the cross section of the rod-shaped vibrating body 1 and the length Y of the cross section of the support members (4, 5).
The ratio should be increased. From the above, it becomes possible to suppress the supporting loss to a minimum.

The rod-shaped vibrating body 1 will be described with reference to FIG.
3A to 3D are detailed views of the rod-shaped vibrating body 1 of FIG.
It is drawn by the third angle method. (A) is a front view, (b)
Is a plan view, (c) is a left side view, and (d) is a right side view. The four surfaces in the longitudinal direction are labeled A to D.

The N end is composed of two triangular surfaces E and F (FIG. 3 (c)). The S end is also composed of two triangular surfaces G and H (FIG. 6D). Surfaces E to H are reflection portions provided to reflect waves traveling in the longitudinal direction,
The fact that the G and H planes are twisted by 90 ° with respect to the E and F planes is the main point of circulating waves without providing a return path outside the drive section.

FIG. 3 (e) is a sectional view of the rod-shaped vibrating body 1 of FIG. The first surface group (A surface, C surface) and the second surface group (B surface,
The lengths of the intervals between the respective surfaces of the cross section of the (D surface) are a and b. (See FIG. 3 (e)). In order to make the natural frequency of the vibration in the direction orthogonal to the surface of the first surface group and the natural frequency of the vibration in the direction orthogonal to the surface of the second surface group substantially the same, in the first embodiment, the a Make b and b the same length. Therefore, the rod-shaped vibrating body 1 is characterized in that the cross-sectional shape thereof is square.

A bending wave traveling on the rod-shaped vibrating body 1 will be described with reference to FIG. A bending wave vibrating in a direction perpendicular to the A-plane and the C-plane is generated by applying a high-frequency voltage to the electromechanical conversion element 2 provided on the A-plane of the rod-shaped vibrating body 1, as shown in FIG. As shown, it progresses from the S end to the N end. Then, by being reflected by the E and F surfaces at the N end, a bending wave oscillating in a direction perpendicular to the B and D surfaces is formed, and travels from the N end to the S end direction.

Further, by being reflected by the G and H surfaces at the S end, it becomes a bending wave that vibrates again in the direction perpendicular to the A and C surfaces, and circulates on the rod-shaped vibrating body 1. In addition, a bending wave vibrating in a direction perpendicular to the A and C planes, and B
A bending wave that oscillates in a direction perpendicular to the plane and the D plane is a polarized wave that is polarized perpendicularly to each other, and thus is incoherent even if the phases match each other.

The surface wave traveling on the rod-shaped vibrating body 1 will be described with reference to FIG. A surface wave that is generated by applying a high frequency voltage to the electromechanical conversion element 2 provided on the A surface of the rod-shaped vibrating body 1 and vibrates in a direction perpendicular to the A surface is
As shown in FIG. 5A, it proceeds from the S end to the N end. Then, it reaches the E surface at the N end and is reflected at the intersection of the E surface and the F surface,
The surface wave reaches the B surface and oscillates in a direction perpendicular to the B surface, and travels from the N end to the S end direction.

Then, it reaches the G surface at the S end, is reflected by the line of intersection of the G surface and the H surface, reaches the C surface and becomes a surface wave oscillating in a direction perpendicular to the C surface, and from the S end to the N end direction. proceed. Then, it reaches the F surface at the N end, is reflected by the line of intersection of the F surface and the E surface, reaches the D surface, and becomes a surface wave oscillating in a direction perpendicular to the D surface.
Proceed from the edge toward the S edge. And it reaches the H side of the S edge,
It is reflected by the line of intersection of the H surface and the G surface, reaches the A surface again, and circulates.

The relationship between the bending wave and the surface wave on the surface of the rod-shaped vibrating body 1 will be described with reference to FIG. Although the circulation of the bending wave has been described with reference to FIG. 4 and the circulation of the surface wave has been described with reference to FIG. 5, these two types of waves have a small attenuation in the deep portion of the rod-shaped vibrating body 1 or the electro-mechanical conversion element 2. When the vibration amplitude due to is large, the bending wave becomes dominant. On the contrary, when the attenuation of the deep portion of the rod-shaped vibrating body 1 is large or the vibration amplitude by the electromechanical conversion element 2 is small, the surface wave becomes dominant.

FIG. 6 shows the two waves on the same drawing. What is important in this figure is that both the bending wave and the surface wave travel in the same direction in the planes A to D in the longitudinal direction. This confirms that the bending wave and the surface wave do not cancel each other out. The electro-mechanical conversion element 2 will be described with reference to FIG.
The configuration and the method of applying power will be described.

The electromechanical conversion element 2 is composed of eight driving piezoelectric elements 2a to 2h and a vibration detecting piezoelectric element 2i. The driving piezoelectric elements 2a to 2h are arranged in pairs so that the polarization directions are alternately reversed as shown in the figure.
In the figure, "+" indicates that the polarization direction is from the front side to the back side of the paper, and "-" indicates that the polarization direction is from the back side to the front side of the paper.

The driving piezoelectric elements 2a, 2c, 2
A high frequency voltage V1 is applied to the surface electrodes every other e, 2g, and a high frequency voltage V2 is applied to the surface electrodes of the remaining driving piezoelectric elements 2b, 2d, 2f and 2h. The high frequency voltage V2 has the same frequency as the high frequency voltage V1 and has a temporal phase difference of π / 2. The back surfaces of the driving piezoelectric elements 2a to 2h are bonded to the surface A of the rod-shaped vibrating body 1 while electrically conducting. Therefore, the rod-shaped vibrating body 1 is connected to the common electrode “GN
D ”.

By applying the high frequency voltages V1 and V2, the driving piezoelectric elements 2a to 2h expand and contract, and progressive waves are generated in the rod-shaped vibrating body 1. A more detailed pattern regarding the generation of the wave is described in Japanese Patent Application Laid-Open No. 60-245482 by the applicant of the present invention, and thus the description thereof is omitted here. The vibration detecting piezoelectric element 2i is for converting the vibration generated in the rod-shaped vibrating body 1 into a voltage, and the input can be controlled while monitoring the magnitude and phase difference of the generated voltage.
The details are described in JP-A-59-204477 and JP-A-61-251490 by the applicant of the present invention, and therefore the description thereof is omitted here (second embodiment). The wave circulation type actuator which is the second embodiment of the present invention will be described with reference to FIG.

FIG. 9 is a perspective view of a wave circulation type actuator. FIG. 10 is a sectional view of a wave circulation type actuator. FIG. 11 is a cross-sectional view of the rod-shaped vibrating body 1. The second embodiment is a modification of the wave circulation type actuator used in the first embodiment.

The same components as those in the first embodiment (excluding the rod-shaped vibrating member) are designated by the same reference numerals, and the description thereof will be omitted. The second embodiment is one in which a plurality of protrusions are provided on the surfaces B and D of the rod-shaped vibrating body 1 of the first embodiment to improve the driving efficiency. In Figure 9,
A plurality of protrusions 10a to 10 are formed on the surfaces B and D of the rod-shaped elastic body 10.
h and 10i-10p are provided. The surface wave generated by the electro-mechanical conversion element 2 provided on the A surface is
Similar to FIG. 1, the moving body 3 is reflected at the N end and the S end, travels to the B surface and the D surface where a plurality of protrusions are provided, and is in pressure contact so as to sandwich the B surface and the D surface (FIG. 10). (See), the rod-shaped vibrating body 1
0 longitudinal drive.

By providing a plurality of protrusions 10a to 10h and 10i to 10p on the B and D surfaces of the rod-shaped elastic body 10, the amplitude of the surface wave is increased and the efficiency is improved. The portion of the rod-shaped elastic body 10 other than the protrusions 10a to 10h and 10i to 10p (the hatched portion in FIG. 11) has a dimension that is larger than that of the portion not provided with the protrusion. The dimension b is designed thicker. As for the vibration of the portion where the protrusion is provided, the natural frequency is lowered due to the additional mass of the protrusion. Therefore, by making the b dimension thicker than the a dimension, the natural frequency of vibration of the portion where the protrusion is provided and the natural frequency of vibration of the portion where the protrusion is not provided are made the same.

[0031]

As described above, according to the present invention, the natural frequency of the vibration of the rod-shaped elastic member in the direction between the first surface groups having the protrusions and the second surface group having the electro-mechanical conversion element Since the wave circulation type actuator is configured so that the natural frequencies of the vibrations in the directions are substantially the same, a wave circulation type actuator having high driving efficiency can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a wave circulation type actuator that is a first embodiment of the present invention.

FIG. 2 is an explanatory diagram related to the supporting method of FIG.

FIG. 3 is a detailed view of the rod-shaped vibrating body 1 of FIG.

FIG. 4 is an explanatory diagram showing a state of circulation of a bending wave.

FIG. 5 is an explanatory diagram showing how a surface wave is circulated.

FIG. 6 is an explanatory diagram in which the surface of the rod-shaped vibrating body 1 is developed.

FIG. 7 is an explanatory diagram of a configuration of the electro-mechanical conversion element 2 and a power supply application method.

FIG. 8 is a cross-sectional view illustrating the relationship among the rod-shaped vibrating body 1, the electro-mechanical conversion element 2, and the moving body 3 in FIG. 1.

FIG. 9 is a perspective view of a wave circulation type actuator that is a second embodiment of the present invention.

10 is a sectional view of FIG. 9.

11 is a cross-sectional view of the rod-shaped vibrating body 1 of FIG.

FIG. 12 is an explanatory diagram of a conventional linear ultrasonic motor.

FIG. 13 is an explanatory diagram of a conventional linear ultrasonic motor.

FIG. 14 is an explanatory diagram of a conventional linear ultrasonic motor.

[Explanation of symbols]

 1, 10 Rod-shaped vibrating body 2, 2a, 2b, 2c Electro-mechanical conversion element, piezoelectric body 3 Moving body 4, 5 Supporting member 6, 7 Fixed part 8, 8a, 8b, 8c Elastic body 9a, 9b Connector 11a, 11b Resonator 12a, 12b Transducer

Claims (4)

[Claims] 1. A first surface group consisting of two opposing surfaces and a second surface group consisting of two opposing surfaces different from the first surface group, wherein the first and second surface groups are in the longitudinal direction. A rod-shaped vibrating body formed on the second vibrating body, an electro-mechanical conversion element that is provided on the second surface group of the rod-shaped vibrating body, and generates a wave traveling in the longitudinal direction of the second surface group; A first reflecting portion provided on the first surface group for reflecting a wave traveling in the longitudinal direction of the second surface group and transmitting the wave to the first surface group; and a wave transmitting to the first surface group traveling in the longitudinal direction. A second reflecting portion that reflects the light and circulates it to the second surface group; and a moving body that is pressed against the rod-shaped vibrating body and moves by the traveling wave motion, and is orthogonal to the surface of the first surface group. The natural frequency of the vibration in the direction and the natural frequency of the vibration in the direction orthogonal to the surface of the second surface group are substantially the same. Wave circulation type actuator characterized and. 2. The wave circulation type actuator according to claim 1, wherein the rod-shaped vibrating body has a square cross-sectional shape. 3. The wave circulation type actuator according to claim 1, wherein a plurality of protrusions are provided on the first surface group of the rod-shaped vibrating body. 4. The wave circulation type actuator according to claim 3, wherein the distance between the two surfaces forming the first surface group is thicker than the distance between the two surfaces forming the second surface group. Characterize.