JPH01308174A - Rotary driven actuator - Google Patents

Abstract

PURPOSE:To smoothly drive a rotor by expanding the displacements of axial piezoelectric elements and the displacement of circumferential piezoelectric elements by belt-shaped elastic members to transmit them to the rotor. CONSTITUTION:A rotary driven actuator is constituted by a rotor 11, stator 12, first and second axial piezoelectric elements 13a and 13b, first and second circumferential piezoelectric elements 14a and 14b, first and second belt-shaped elastic members 15a and 15b, a bearing 16, a bearing 17, a supporting plate 18 and drive contact parts 19a and 19b. The axial piezoelectric elements 13a and 13b are connected to the belt-shaped elastic members 15a and 15b, and the displacement of the axial piezoelectric elements 13a and 13b is expanded to be the displacement in the drive contact parts 19a and 19b of the belt-shaped elastic members 15a and 15b. The circumferential piezoelectric elements 14a and 14b similarly are displaced at the drive contact parts 19a and 19b. Thus when the circumferential piezoelectric elements 14a and 14b extend and contract, the drive contact parts 19a and 19b in the circumferential direction of the rotor 11, and it is rotated by equalizing the drive frequencies of both the elements 13a to 14b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary drive actuator using a piezoelectric element.

[Conventional technology]

FIG. 9(&) is a partial sectional view of a rotary drive actuator using a conventional piezoelectric element, as shown in Japanese Unexamined Patent Publication No. 60-20'/'75, and FIG. This is a cross-sectional view taken along line IX (b) - IX Cb') in figure (a), and in the figure, (1) is the casing, (2) is the shaft, (3) is the bearing, and (4) is the piezoelectric body. . Moreover, FIG. 10 is a configuration diagram showing the driving state of a conventional rotary drive actuator, and in the figure, (4A) is a moving part, (5A), (5
B) # (6A) l (6B) is the electrode, (7) +
(8) is a power source.

Next, the operation will be explained. As shown by the arrow (A) in FIG. 10, the piezoelectric body (4) is polarized.

A pair of electrodes (
5A), (5B) and (6A), (6B) are provided.

A sinusoidal voltage is applied to the electrode (5A) by the power supply (7),
(5B) produces a vibration mode in the same direction as the polarization (A) direction. Further, when a sinusoidal voltage is applied to the electrodes (6A) and (6B) by the power source (8), a vibration mode in a direction orthogonal to the polarization (A) is generated. Therefore, a sinusoidal voltage with equal frequency and a 90 degree phase difference is applied to each electrode (5
A).

(5B) and (6A)? (6B) causes the moving part (4A) of the piezoelectric body (4) to draw an elliptical orbit shown by the arrow (E) in FIG. Then, the moving part (4A) contacts the inner surface of the casing (1) at the upper part of the elliptical orbital movement and generates a rotational driving force.

[Problem to be solved by the invention]

Conventional rotary drive actuators using piezoelectric elements are configured as described above, and since the displacement of the piezoelectric element of several μm at most is directly utilized, the processing accuracy of each component must be extremely high. In addition, there were problems in that it was difficult to drive due to thermal expansion and contraction due to changes in humidity, making it difficult to say that it was a practical configuration.

This invention was developed to solve the above-mentioned problems, and it is a rotary drive with a practical configuration that does not require high machining accuracy of each component and is less affected by thermal expansion and temperature changes. The purpose is to obtain an actuator.

[Failure to solve the problem]

The rotational drive actuator according to the present invention magnifies the displacement of the axial piezoelectric element and the circumferential piezoelectric element using a band-shaped elastic body, and transmits the expanded displacement to the rotor to drive the rotor.

[Effect]

The displacement of the piezoelectric element is magnified by the band-shaped elastic body and becomes the displacement of the driving contact portion. [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway perspective view of a rotary drive actuator according to an embodiment of the present invention. In the figure, αp is a rotor, (6) is a stator, (138L) is a first axial piezoelectric element, (14-) is a first circumferential piezoelectric element, which is connected to the first elastic band (15-). (13b
) is a second axial piezoelectric element, (14b) is a second circumferential piezoelectric element, and is connected to the second band-shaped elastic body (15b). (to) is the bearing, 071 is the shaft, (to) is the support plate,
(19-) is a driving contact portion on the first elastic band (15-), and (, 9b) is a driving contact portion on the second elastic band (15b).

Next, the operation will be explained. As shown in the configuration diagram in FIG. 2 showing the f'+4+ state of the rotary drive actuator according to an embodiment of the present invention, an axial piezoelectric element (13a),
(13b) is a band-shaped elastic body (15a), (15b)
The axial piezoelectric elements (13a), (1
The displacement of sb) is expanded, and the elastic band (15-)
(15b) drive contact parts (19a), (19b)
The displacement is . Axial piezoelectric element (131L),
(1sb) expands, the band-shaped elastic body (15a),
(15b) moves in the direction away from the rotor 01), and when the axial piezoelectric elements (13a) and (13b) contract, the band-shaped elastic bodies (15a) and (15b) move in the direction closer to the rotor (sha). . Circumferential piezoelectric element (14-),
(14b) is connected to the band-shaped elastic bodies (15a) and (lδb) as shown in the configuration diagram of FIG. The displacements of (14a) and (14b) are magnified and drive contact parts (19a) and (19b)
The displacement is .

When the circumferential piezoelectric elements (14a) and (14-'b) expand and contract, the driving contact portions (19a) and (19b) move in the circumferential direction of the rotor (11). Axial piezoelectric element (
lj5a), (13b) and circumferential piezoelectric element (14a
) and (14b) are made equal in driving frequency to rotate the rotor.

Next, FIG. 4 is a partially cutaway perspective view of a rotary drive actuator according to another embodiment of the present invention, α9 is an axial piezoelectric element, 041 is a circumferential piezoelectric element, αG is a band-shaped elastic body,
α0 is a driving contact portion on the elastic band. Figure 5(a)
(b) is a front view and a side view of a band-shaped elastic body related to a rotary drive actuator according to another embodiment of the present invention, respectively. , in the example shown in FIG. 5, they are manufactured in one piece. Similar to the example shown in FIG. 1, the axial piezoelectric element 0
When QI3 is displaced, the elastic band QI3 moves toward or away from the rotor (11). However, the driving torque is generated by the circumferential piezoelectric element (14) in the same manner as in the example shown in FIG. 1. In the example shown in Fig. 4, the band-shaped elastic body has a shape as shown in Fig. 5, so when the circumferential piezoelectric element α is driven at the resonance frequency of the system or at a frequency close to the resonance frequency, the band-shaped elastic body The drive contact portion αI (2) produces a large displacement, allowing the rotor 01) to rotate at high speed. If the circumferential piezoelectric element α4 is driven away from the resonance frequency of the system, the rotor 0 can be rotated with high accuracy, and positioning can be performed with high accuracy.

In the above embodiment, the band-shaped elastic body is separated at its tip as shown in the perspective view of the band-shaped elastic body related to the rotary drive actuator of the embodiment of the present invention in FIG.
A plurality of 9 may be provided. Further, the number of piezoelectric elements may be different from the embodiment. For example, the example shown in FIG. 1 may be configured as shown in FIG. 7, which is a configuration diagram of a piezoelectric element and a band-shaped elastic body related to a rotary drive actuator according to an embodiment of the present invention. The example shown in FIG. 4 may be configured as shown in FIG. 8, which is a configuration diagram of a piezoelectric element and a band-shaped elastic body related to a rotary drive actuator according to an embodiment of the present invention. The invention uses a belt-shaped elastic body to magnify the displacement of the piezoelectric element in the axial direction and the displacement of the piezoelectric element in the circumferential direction, and transmits it to the rotor to drive the rotor.
It is possible to obtain a rotary drive actuator that does not require high machining accuracy of each component, has smooth drive even under temperature changes, and can provide a practical rotary drive actuator.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a rotary drive actuator according to an embodiment of the present invention, and FIGS. 4 is a partially cutaway perspective view of a rotary drive actuator according to another embodiment of the present invention, and FIG. 5(a)
(b) is a front view and a side view of a band-shaped elastic body related to a rotary drive actuator according to another embodiment of the present invention, and FIG. 6 is a perspective view of a band-shaped elastic body related to a rotation drive actuator according to an embodiment of the present invention. 7 and 8 are configuration diagrams of a piezoelectric element and a band-shaped elastic body related to a rotary drive actuator according to an embodiment of the present invention, FIG. 9(a) is a partial sectional view of a conventional rotary drive actuator, and FIG. b) is a sectional view taken along line IX(b)--(b) in FIG. 9(,), and FIG. 10 is a configuration diagram showing the driving state of a conventional rotary drive actuator. In the figure, 0°C is the rotor, (to), (13a),
(1, 3b) is an axial piezoelectric element, σ411 (141
L) + (14b) is a circumferential piezoelectric element, QI191
(15a) + (15b) is a band-shaped elastic body. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A rotary drive actuator that magnifies the displacement of an axial piezoelectric element and the circumferential piezoelectric element using a band-shaped elastic body, and transmits the amplified displacement to a rotor to drive the rotor.