JPS6020775A - Rotary actuator - Google Patents

Abstract

PURPOSE:To transmit a drive force in high efficiency by rotating a rotary member by the moving unit for producing circulating locus of a piezoelectric unit. CONSTITUTION:A shaft 2 is rotatably supported to a casing 1 via a bearing 3. A piezoelectric unit 4 has a movable unit 4A for producing a circulating locus by distortions of the longitudinal or lateral effect and shearing effect. A plurality of units 4 are secured to the shaft 2 to have a gap to the inner surface of the casing 1 at the movable unit 4A. AC power source is supplied to the unit 4, and the casing 1 or shaft 2 is rotated by the unit 4A for producing the circulating locus.

Description

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

[Background of the invention]

Conventionally, DC servo motors, AC servo motors, hydraulic motors, and the like have been used as drive actuators for drive parts that require low speed and high torque, such as robot joints. Hydraulic motors can be driven at low speeds and high torque, but there are problems with oil leakage and the need for a large hydraulic power source.In addition, electric motors have a rated rotational speed of 10,000, so when used for parts that drive at low speeds, they must be decelerated. machine becomes essential. The use of this speed reducer causes problems such as increased weight and decreased rigidity.

On the other hand, in recent years, with the development of piezoelectric elements, various drive devices using piezoelectric elements have been proposed.

This piezoelectric element exhibits a so-called piezoelectric effect, which causes distortion when a voltage is applied to it, and has been known for a long time. Examples of rotary actuators using this piezoelectric element are those described in JP-A-53-82286 and JP-A-57-78378. These rotary actuator actuators have two piezoelectric bodies arranged in perpendicular directions, each having a type of longitudinal strain effect or transverse strain effect, in order to apply driving force to the driven object through contact. The two piezoelectric bodies are connected by a flexible structure in order to construct a power transmission section having orbital motion by fully synthesizing each strain form.

When a rotary actuator using this type of piezoelectric element is applied to the drive section that requires low speed and high torque as described above, since it has a power transmission section of a flexible structure, the drive section Currently, high torque cannot be transmitted with high efficiency.

[Purpose of the invention]

The present invention was made based on the above-mentioned matters, and an object of the present invention is to provide a rotary actuator that can transmit driving force with high efficiency.

[Summary of the invention]

The present invention is characterized in that a rotary actuator that outputs rotational force includes a cylindrical body;

A piezoelectric device having a shaft rotatably supported within a cylinder, and a moving part that generates a circumferential motion locus due to strain caused by a longitudinal effect, a transverse effect, and a shear effect, on either the cylinder or the shaft. and a power supply means for supplying alternating current power to the piezoelectric body, and the rotating member of the other of the cylindrical body and the shaft body is rotated by a moving part that generates a circular movement locus of the piezoelectric body. This is what I did.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the rotary actuator of the present invention. In these figures, 1 is a casing, and 2 is a shaft rotatably supported by the casing 1 by a bearing 3. FIG. Reference numeral 1 denotes a piezoelectric body including a moving part 4A that draws a circular contact locus B. As shown in FIG.
A plurality of numbers (six in this example) are fixed. Further, in this embodiment, as shown in FIG. 1, a group of six piezoelectric bodies provided in the circumferential direction at one axial position is arranged in two stages in the axial direction.

The detailed structure of one embodiment of the piezoelectric body 4 described above is shown in FIGS. 3 to 6.
This will be explained using figures.

In this example, the piezoelectric body 4 is formed into a rectangular parallelepiped shape. This piezoelectric body 4 is made of, for example, lead zirconate titanate (Pb (Z
r, Tl0a) (abbreviated as PZT). Furthermore, this piezoelectric body 4 is polarized as shown by arrow A. This polarization treatment may be performed in advance, or the piezoelectric body 4 may be assembled later. Pairs of electrodes 5A, 5B and 6A are provided on the opposing surface perpendicular to the polarization A and the opposing surface parallel to the polarization A of the piezoelectric body 4, respectively.
, 6B are provided. These pairs of electrodes 5A, 5B
and 6A, 6B are connected to power sources 7, 8, respectively, through slip rings (not shown) provided on the shaft body 2. For the electrodes 5A, 5B and 6A, 6B described above, for example, an electrode plate, a vapor-deposited electrode, or the like is used. And electrodes! 5A, 5B, 6A.

In order to ensure insulation between the electrodes, it is preferable to provide the electrodes 6B not over the entire surface of each opposing surface of the piezoelectric body 4, but at a very small distance from the corner of the adjacent surface. Electrode 5A as described above.

The piezoelectric body 2 including 5B, 6A, and 6B is an electrode 5B.

It is fixed to the shaft body 2 via a fixing plate 9. The fixed plate 9 is made of an electrically insulating material such as alumina ceramics. Since the electrode 58 portion of the piezoelectric body 4 becomes a moving portion that contacts the inner surface of the casing l and applies rotational driving force to the shaft body 2, a wear-resistant member 10 is provided to prevent wear of this portion.

Attachment of this member 10 is not essential. This member 10 is preferably made of an electrically insulating material such as alumina ceramics. The power source 7.8 described above can output an alternating current voltage with an arbitrary waveform of an arbitrary frequency such as a sine wave, a rectangular wave, a triangular wave, a trapezoidal wave, etc., for example. By changing the frequency and waveform of this alternating current voltage, the circular movement locus B of the moving section 4A can be changed into various shapes. In other words, you can control the rotation speed.

Next, the operation of one embodiment of the above-mentioned rotary actuator of the present invention will be described.

Now, apply a sine wave voltage to the 5 electrodes using the power supply 7.

5B, the compressed body 4 generates a vibration mode in the same direction as the polarization A direction (so-called longitudinal strain effect), as shown by the two-dot chain line in FIG. Furthermore, when a sinusoidal voltage is applied to the electrodes 6A and 6B by the power source 8, the piezoelectric body 4 exhibits a vibration mode in a direction perpendicular to the polarization A (so-called shear strain effect), as shown by the two-dot chain line in FIG. arise. For this reason, the power supply 7,
Sine wave voltage with equal frequency and 90 degree phase difference from 8?
, respectively, to the electrodes 5A, 5B and the electrodes 6A, 6B, the moving part 4A of the piezoelectric body 4 undergoes a synthesis of the longitudinal strain effect and the shear strain effect of the piezoelectric body 4.
As shown in the figure, an elliptical orbit indicated by arrow B is drawn in the plane of the X and Z axes of the orthogonal coordinate system. 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.

At this time, if the casing l is held fixed, the shaft body 2 will rotate clockwise in FIG. Conversely, if the shaft body 2 is held fixed.

The casing 1 rotates counterclockwise in FIG.

Furthermore, by setting the phases of the voltages from the power sources 7 and 8 in the opposite direction to that described above, the shaft body 2 or the casing 1 can be rotated in the opposite direction to that described above. Furthermore, since the orbital movement of the piezoelectric body 4 itself is directly transmitted to the shaft body 2 or the casing 1, the driving force can be transmitted with high efficiency.

In the above-mentioned embodiment, the longitudinal strain effect and the shear strain effect are applied to the piezoelectric body 4, and by combining these effects, the movable portion 4A is given circular locus motion, but as shown in FIG. The piezoelectric body 4 is attached to the fixed plate 9 so that the direction of polarization A of the piezoelectric body 40 is lateral, and a transverse strain effect and a shear strain effect are applied to the piezoelectric body 4, so that the movable part 4A has a circular movement locus B. It is also possible to draw it. Furthermore, it is also possible to use a stack of these piezoelectric bodies 4. In this case, a large rotational driving force can be obtained. Further, in the above example, each piezoelectric body 4 is configured to have a longitudinal strain effect, a transverse strain effect, and a shear strain effect, but as shown in FIG. It is also possible to laminate the piezoelectric material 4C and the piezoelectric material 4C that produces a shear strain effect.

It is also possible to stack a plurality of these piezoelectric bodies 4B and 4c as a unit.

An embodiment of the rotary actuator of the present invention shown in FIGS. 1 and 2 includes two members L1. FIG. 9 shows an example in which the present invention is applied to the drive section of L2. In this figure, parts with the same reference numerals as in FIGS. 1 and 2 are the same parts. In this example, the shaft body 4 of the embodiment of the rotary actuator of the present invention shown in FIG. 1 is fixed to one member L1, and the casing 1 is fixed to the other member L2. With this configuration, the piezoelectric body 4 has a movable portion 4A drawing a circular movement locus, which contacts the inner surface of the casing 1 and applies a driving force to the casing 1. Therefore, the other member L2 is driven relative to the one member L1. According to this example:
The rotary actuator of the present invention is connected to member L1. Since it can be built into the L20 connection part, the structure of the drive part can be simplified. Moreover, the moving part of the piezoelectric body 4 is in direct contact with the casing 1 81! and drive this with
Driving force can be transmitted with high efficiency. Furthermore, a large driving force can be output by providing a plurality of piezoelectric units around the shaft along the axial direction.

10 and 11 show another embodiment of the rotary actuator of the present invention, in which the moving part 4A of the piezoelectric body 4 has a gap with the outer peripheral surface of the shaft body 2. , a plurality of piezoelectric bodies 4 are fixed to the inner surface of the casing 1 along the shaft rotation. This embodiment can exhibit the same functions and effects as the embodiment shown in FIG. FIG. 12 shows an example in which another embodiment of the rotary actuator of the present invention shown in FIG. 10 is applied to a driving section of two relatively rotating members Lr and L2. In this example, the same operation and effect as the application example shown in FIG. 9 can be achieved.

FIGS. 13 to 15 show still another embodiment of the rotary actuator of the present invention, and this embodiment shows an insert body 1
1 between two disc-shaped elastic members 12, and the shaft body 2
A disk 13 is provided on one surface of the elastic member 12, and a plurality of piezoelectric bodies 4 each having a moving part 4A that generates a circumferential locus movement are provided on the inner surface of the casing facing the disk 13. It is composed of three parts.

In this example, eight piezoelectric bodies 4 are arranged as shown in FIG.

In still another embodiment of the rotary actuator of the present invention shown in FIG. 13, a moving portion 4A that draws a circular movement locus of the piezoelectric body 4 comes into contact with the disk 13 to transmit a driving force as shown in FIG. 16. At this time, if the casing 1 is held fixed, the shaft body 2 can be rotated, and conversely, if the shaft body 2 is held fixed, the casing 1 can be rotated. According to this embodiment, the same effects as the embodiments shown in FIGS. 1 and 10 described above can be achieved, and the axial dimension of the shaft body 2 can be reduced.

The rotary actuator of the present invention shown in FIG. 13.

- In another embodiment, two members L that rotate relative to each other.
FIG. 17 shows an example in which this method is applied to the connecting portion of L and Lm.

FIG. 18 shows another embodiment of the rotary actuator of the present invention, and in comparison with the embodiment shown in FIG. 13, this embodiment has a disk 13 fixed to the inner surface of the casing 1. One elastic member 12 facing
A plurality of piezoelectric bodies 4 are provided. With this configuration, as shown in FIG. 19, the moving portion 4A of the piezoelectric body 4 comes into contact with the disk 13 along its circular movement locus and transmits a driving force. At this time, if the casing is held fixed, the shaft body 2 can be rotated, and conversely, if the shaft body 2 is held fixed, the casing 2 can be rotated. According to this embodiment, the same effects as the embodiment shown in FIG. 13 can be achieved. FIG. 20 shows an example in which this embodiment is applied to a connecting portion of two parts #, Lx, and Lx that rotate relatively.

FIG. 21 shows still another embodiment of the rotary actuator of the present invention. In this embodiment, disks 13 are provided on both sides of the elastic member 12, and these disks 1
On the inner surface of the casing 1 facing the piezoelectric body 3, a plurality of piezoelectric bodies 4 each having a moving part 4A that generates a circular locus movement are provided. With this configuration, as shown in FIG. 22, the movable portions 4A of the piezoelectric body 4 come into contact with the disks 13 on both sides of the elastic member 12, and driving force is transmitted. At this time, if the casing 1 is held fixed,
The shaft body 2 can be rotated. On the contrary, shaft body 2
If it is held fixed, the casing 1 can be rotated. According to this embodiment, FIGS.
The transmitted torque can be doubled compared to the embodiment shown in the figure.

Two members L that relatively rotate the embodiment shown in FIG.
1. FIG. 23 shows an example in which this method is applied to the connecting portion of L2.

FIG. 24 shows another embodiment of the rotary healing actuator of the present invention, and this embodiment differs from the embodiment shown in FIG. 21 in that the mounting of the disk 13 and the piezoelectric body 4 is different. be. Due to this configuration, the second
The same effects as the embodiment shown in FIG. 1 can be achieved. In addition, in this embodiment, two members L1. Lz
FIG. 25 shows an example in which this method is applied to a connecting portion.

In addition, in the above-described embodiment of the present invention, if the friction coefficient of the moving part 4A of the piezoelectric body 4 and the part facing it is increased, slippage will not occur and the driving force can be transmitted with high efficiency. I can do it.

Next, the rotational speed obtained in the rotary actuator of the embodiment shown in FIG. 13 will be described.

As the piezoelectric body 4, a single piezoelectric body capable of producing a longitudinal strain effect and a shear strain effect is used. and piezoelectric body 4
is a square prism with a length t of 2 squares, the number Nm of layers of this piezoelectric body 4 laminated along a plane parallel to the disk 13 is 15, and the number NA of layers laminated along a direction perpendicular to the disk 13 is 1
5. The piezoelectric constant VA due to the longitudinal strain effect of this piezoelectric body 4 is set to 600X 1 o-12 (m/V), and the piezoelectric constant Vs due to the shear hismi effect is 900X10-12 (m/V).
m/V) and the applied voltage (■) is 500V, the displacement DA of the moving part of the laminated piezoelectric body in the disk direction is DA
=VA X V X NA =4.5 μm (1). Also, when the applied voltage () is set to 40 V, the amount of displacement D per one step of driving the disk in the circumferential direction is D! l is DB=VpowerXVXNm=0.54μm...(2). Twelve stacked piezoelectric units are arranged in the circumferential direction, and these piezoelectric units are divided into two sets and driven with a phase difference of 180 degrees. The piezoelectric moving part contacts and drives the disk 13 twice in one cycle. Further, if the piezoelectric body unit is placed at a position 20 m in the radial direction from the center of the shaft body 2, and the frequency of the applied voltage ■ is 20 KH2,
The rotational circumferential speed U of the disk is as follows.・=0.0216 (m/S) -=-<3) Next, the rotation speed N is as follows.

= 10.3 rpm (4) [Effects of the Invention] As described above, according to the present invention, it is possible to provide a rotary actuator that can output rotational driving force with high efficiency. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the rotary actuator of the present invention, FIG.
The figure is a side view showing the configuration of an example of a piezoelectric body used in the actuator of the present invention, Figure 4 is a perspective view thereof, Figures 5 and 6 are illustrations of its operation, and Figure 7 is a piezoelectric body used in the present invention. FIG. 8 is a perspective view showing the configuration of another example of the piezoelectric body used in the present invention, and FIG. 9 is a perspective view showing the configuration of still another example of the piezoelectric body used in the present invention. A sectional view showing an application example of one embodiment of the rotary type actuator, FIG. 1θ is a longitudinal sectional view showing another embodiment of the rotary type actuator of the present invention,
11 is a sectional view taken along the line Xl-XI in FIG. 10, FIG. 12 is a sectional view showing an application example of the actuator shown in FIG. 10, and FIG. 13 is a further embodiment of the rotary actuator of the present invention. Fig. 14 is a vertical cross-sectional view showing the W-■ of Fig. 13.
15 is a sectional view taken along the ff-XV arrow in FIG. 13, FIG. 16 is a diagram explaining the operation of the actuator shown in FIG. 13, and FIG. 17 is an application of the actuator shown in FIG. 13. 18 is a longitudinal sectional view showing another embodiment of the rotation actuator of the present invention, FIG. 19 is an explanatory diagram of its operation, and FIG. 20 is an example of application of the actuator shown in FIG. 18. FIG. 21 is a longitudinal sectional view showing still another embodiment of the rotary actuator of the present invention.
2 is an explanatory diagram of its operation, FIG. 23 is a sectional view showing an example of its application, FIG. 24 is a longitudinal sectional view showing another embodiment of the rotary actuator of the present invention, and FIG. 25 is an explanatory diagram of its operation, 26 is a sectional view showing an example of its application. 1...Casing, 2...Shaft body, 3...Bearing, 4
．． 4B. 4C...piezoelectric body, 5A, 5B, 6A, 6B...electrode, 7.8...power supply. Agent Patent Attorney Akio Takahashi r q Figure χlθ Figure 11% 12 Figure z 4 1 Compensation/y rJ Tutorial 1f -' T- ~ 1 7iA. The top is 2%/7 Figure fJ, tg Figure 2θ 1 Figure not 21 Figure 22 Figure''''y5 Z, 3 Figure ■ 74 Rofu 26 Mouth

Claims (1)

[Claims] 1. In a rotary actuator that outputs rotational force,
A cylindrical body, a shaft body rotatably supported within the cylindrical body, and a circumferential motion locus caused by strain due to longitudinal or transverse effects and shear effects in either the cylinder body or the shaft body. The piezoelectric body includes a piezoelectric body having a moving part, and a power supply means for supplying alternating current power to the piezoelectric body, and the rotating member of either the cylinder body or the shaft body is rotated by the moving part that generates a circular motion locus of the piezoelectric body. A rotary actuator that rotates by t%. 2. The rotary actuator according to claim 1, wherein a plurality of the piezoelectric bodies are provided around the shaft body so that the moving portion thereof has a gap with respect to the inner surface of the casing. rotary actuator. 3. The rotary actuator according to claim 1, wherein a plurality of the piezoelectric bodies are provided on the inner surface of the casing so that the moving parts thereof are four spaces apart from the outer peripheral surface of the shaft body. rotary actuator. 4. The rotary actuator according to claim 2 or 3, wherein the plurality of piezoelectric bodies are provided in plural sets in the axial direction of the shaft body. 5. In the rotary actuator according to claim 1, a disc body is provided on the shaft body, and a piezoelectric body is mounted on one side of the disc body so that a moving part of the piezoelectric body faces. A rotary actuator characterized by being fixed to a casing. 6.% Allowance In the rotary actuator according to claim 1, the shaft body is provided with a disc body, and the piezoelectric body is attached to the disc body so that the moving part of the piezoelectric body faces the inner surface of the casing. A rotary actuator characterized by being fixed to either side. 7. In the rotary actuator according to any one of claims 2 to 6, the piezoelectric body causes the moving part to follow a circular motion trajectory by combining a longitudinal strain effect and a shear strain effect. A rotary actuator that features drawing. 8. In the rotary actuator according to any one of claims 2 to 6, the piezoelectric body has a movable portion that follows a circular motion trajectory due to the combination of a transverse strain effect and a shear strain effect. A rotary actuator that features drawing. 9. In the rotary actuator according to any one of claims 2 to 6, the piezoelectric body is formed by laminating a piezoelectric body that causes a longitudinal strain effect and a piezoelectric body that causes a shear strain effect. A rotary actuator characterized in that the moving part thereof draws a circular motion locus. 10. In the rotary actuator according to any one of claims 2 to 6, the piezoelectric body is formed by laminating a piezoelectric body that causes a transverse strain effect and a piezoelectric body that causes a shear strain effect. A rotary actuator characterized in that the moving part thereof draws a circular motion locus.