JPH0251367A - Electrostatic actuator - Google Patents

Abstract

PURPOSE:To miniaturize an apparatus by constituting a capacitor group from respective pluralities of first and second electrodes and by selectively charging the part between said electrodes with electricity through a switching circuit to cause an electrostatic force to act on said group. CONSTITUTION:In the sun cylinder 1 of a first tubular body fixed at a stationary part, an output shaft 2 is supported in the central part of a flat, bottomed base wall 1a via a bearing 3. Then, e.g., eight first electrodes 4a-4h are arranged at a given pitch so as to be embedded in the inner peripheral face of said cylinder 1 and an insulating film 5 of high dielectric constant is attached to the whole inner peripheral face in the manner of covering said electrodes 4a-4h. Further, the planet cylinder 6 of a second tubular body is smaller in diameter than the sun cylinder 1, its base wall part 6a is arranged in said cylinder 1, and said planet cylinder 6 is connected with the output shaft 2 via a universal coupling 7. Second electrodes 8a-8g are arranged so as to be embedded in the inner peripheral face of said planet cylinder 6 to form a capacitor group. Thus, the part between said electrodes is selectively charged with electricity by change-over switches 10a-10h of a switching circuit 9 and a torque is taken out.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an electrostatic actuator that uses electrostatic force to drive a load, particularly for industrial robots, precision machines, The present invention relates to electrostatic actuators used to drive mechanical parts of automobile equipment parts, home appliances, office automation equipment, medical equipment, etc.

(Conventional technology) Traditionally, servo motors, linear motors, stepping motors, etc. have been used exclusively to drive the mechanical parts of industrial robots, precision machines, automobile equipment parts, home appliances, office automation equipment, medical equipment, etc. Magnetic actuators are used, and electrostatic actuators for driving the above-mentioned mechanical parts are just on the verge of practical application.

(Problem to be solved by the invention) In recent years, there has been an increase in demand for technologies that require higher power density and higher power density of actuators for driving the above-mentioned mechanical parts, more complex drive patterns, and control of minute displacements. It's coming. However, conventional magnetic actuators are approaching their performance limits due to processing technology and physical constraints, and further miniaturization is not realistic as it will only cause negative effects such as a significant drop in performance. . In addition, it is difficult to manufacture small motors that can obtain high torque at low speeds, and of course, reduction gears are also used to obtain high torque, but this This becomes an obstacle to downsizing the entire device.

The present invention has been made in view of the above circumstances, and its purpose is to make it possible to reduce the overall size and to achieve high output torque without reducing the resolution of output control. An object of the present invention is to provide an electrostatic actuator that exhibits the following effects.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, an electrostatic actuator according to the present invention includes a first cylindrical body and a diameter smaller than that of the first cylindrical body. a second cylindrical body arranged in the first cylindrical body; first electrode ζ
and a plurality of second electrodes arranged at a predetermined pitch in the circumferential direction on the outer circumferential surface of the second cylindrical body, and these first electrodes.
The second cylindrical body is connected to the first by selectively charging between the second electrodes and applying an electrostatic force between the two electrodes.
A switching circuit is provided for relatively planetary rotation along the inner circumferential surface of the cylindrical body, and the rotational force is extracted from one of the first and second cylindrical bodies.

In addition, after providing the first cylindrical body and the second cylindrical body similar to the above, it is possible to extend a plurality of first electrodes arranged at a predetermined pitch; and a plurality of first electrodes disposed on the outer circumferential surface of the second cylindrical body or the inner circumferential surface of the first cylindrical body over the entire circumferential direction thereof. The second cylindrical body is connected to the inner periphery of the first cylindrical body by selectively charging the second electrode and between the first and second electrodes to apply an electrostatic force between the two electrodes. A configuration may also be adopted in which a switching circuit is provided to rotate the rotation star relative to each other along the surface, and the rotational force is extracted from one of the first and second cylindrical bodies.

A plurality of pairs of the first cylindrical body and the second cylindrical body are provided in a connected state for each cylindrical body, and the inner circumferential surface of each of the first cylindrical bodies and the second cylindrical body are It is also possible to provide a first electrode and a second electrode on each outer circumferential surface of the shaped body.

(Function) A capacitor group is constituted by a plurality of first electrodes and a plurality of second electrodes, and the switching circuit selectively charges between the first and second electrodes to form a picture electrode. By applying an electrostatic force, the second cylindrical body is planetarily rotated relative to the inner peripheral surface of the first cylindrical body. As a result, an internal reduction function can be obtained, and when the rotational force is extracted from one of the first and second cylindrical bodies, the torque of the rotational force increases in accordance with the reduction ratio.

Also, when a plurality of first electrodes and a second electrode extending over the entire circumferential direction are provided on the outer peripheral surface of the first cylindrical body or the inner peripheral surface of the second cylindrical body, the switching circuit This enables the second cylindrical body to be planetarily rotated relative to the inner peripheral surface of the first cylindrical body, and due to the accompanying internal deceleration function, one of the first and second cylindrical bodies The torque of the rotational force extracted from the engine increases.

Furthermore, if a plurality of pairs of the first cylindrical body and the second cylindrical body are provided in a state where each cylindrical body is connected, the torques generated in each pair will be superimposed. The torque of the rotational force extracted as described above becomes even larger.

(Example) First, a first example of the present invention will be described with reference to FIGS. 1 and 2.

In Figures 1 and 2, numeral 1 denotes a solar cylinder, which is a first cylindrical body fixed to a stationary part as appropriate, and is formed into a flat bottomed shape from a non-conductive material with relatively high rigidity. An output shaft 2 is supported through a bearing 3 at the center of the bottom wall 1a. For example, eight first electrodes 4a to 4 are arranged on the inner peripheral surface of the solar cylinder 1.
4h are arranged in an embedded manner in the circumferential direction at even pitches (equal pitches). Further, an insulating coating 5 having a high dielectric constant is uniformly attached to the entire inner peripheral surface of the solar cylinder 1 so as to cover the electrodes 48 to 4h.

Reference numeral 6 denotes a planetary cylinder as a second cylindrical body, which is formed of a non-conductive material with relatively high rigidity into a flat bottomed shape with a diameter smaller than that of the solar cylinder 1. It is arranged with the bottom wall part 6a on the front side (opening edge side of the solar cylinder 1), and in this arrangement state, the center part of the bottom wall part 6a is connected to the output shaft 2 via the universal joint 7. There is. Therefore, when the planetary cylinder 6 is subjected to relative planetary motion along the inner peripheral surface of the solar cylinder 1, since the solar cylinder 1 is in a fixed state, the rotational force of the planetary cylinder 6 is transferred to the output shaft. It can be taken out from 2. Then, on the inner peripheral surface of the planetary cylinder 6, for example, seven second electrodes 8a to 8g, which are smaller than the first electrodes 4a to 4h, are arranged in the circumferential direction of the first electrodes 8a to 8g.
The second electrodes 8a to 8g and the first electrodes 4a to 4h are arranged in a buried manner at the same pitch as the electrodes 4a to 4h, and a group of capacitors is formed with an insulating film 5 interposed between the second electrodes 8a to 8g and the first electrodes 4a to 4h. will be done. The dimensional relationship between the inner diameter of the solar cylinder 1 and the outer diameter of the planetary cylinder 6 is such that the arrangement pitches of the first electrodes 4a to 4h and the second electrodes 88 to 8g are equal (8 near in this case). It is set.

Therefore, as shown in FIG. 1, the second electrodes 8a to 8g
are commonly connected to the ground terminal, and the first electrodes 4a to 4
h is a changeover switch 10a included in the switching circuit 9;
~10h are individually connected to each common contact C. At this time, each of the changeover switches 10a to 10h has a state in which the corresponding first electrode 4a to 4h is connected to the positive electrode side of the DC power supply 11 via the contact point (c-a), and a state in which the corresponding first electrode 4a to 4h is connected to the positive electrode side of the DC power supply 11 via the contact point (ca), and
It is possible to switch between a to 4h connected to the ground terminal via the contacts (c and b).

Note that the negative pole of the DC power supply 11 is connected to a ground terminal.

Next, the operation of the above configuration will be explained. Now, in a state where the solar cylinder 1 and the planetary cylinder 6 are in the positional relationship as shown in FIG. and a DC power supply 1 to the first electrodes 4a, 4b, 4c.
Voltage starts to be applied from 1. Then, the first electrode 4a.

The capacitors formed by each pair of electrodes 4b, 4c and second electrodes 8a, 8b, and 3c are charged, and an attractive force due to electrostatic force acts between each pair of electrodes, and in response, the planet The cylinder 6 begins to rotate (rotate) counterclockwise. When the planetary cylinder 6 is rotated in this way, as shown in FIG. In this case, the suction force acting between the electrodes 4a and 8c will impede the rotation. Therefore, in reality, just before the contact point between the first electrode 4a and the second electrode 8a passes the midpoint between the electrodes 4a and 8a, the changeover switch 10a is turned on between the contacts (c and b). The electrode 4a is switched to the above electrode 4a.

While discharging the charge between 8a and the selector switch 10
d to the on state between the contacts (c and a), and the first electrode 4
An attractive force due to electrostatic force is applied between the electrode d and the second electrode 8d. From this point on, each changeover switch 10b to 1
By sequentially switching 0h and 10a as described above, the planetary cylinder 6 is prevented from rotating counterclockwise (
It can be rotated clockwise from
The output shaft 2 is rotated in accordance with such planetary rotation of the planetary cylinder 6. In FIG. 1, Sl and S2 are the rotation center and revolution center of the planetary cylinder 6, respectively.

By the way, when the number of electrodes of the planetary cylinder 6 is n and the number of electrodes of the solar cylinder 1 is m, in order for the planetary cylinder 6 to rotate once, the first electrodes 4a to 4h and the second electrodes 88 to 8g must be It is necessary that the contact point between them rotates the inner circumferential surface of the solar cylinder 1 by m/(m−n). Therefore, the output torque of the output shaft 2 is generated when the contact points between the first electrodes 48 to 4h and the second electrodes 8a to 8g rotate once, in other words, when the planetary cylinder 6 revolves once. It is approximately m/(m-n) times the torque.

In other words, according to this embodiment in which m-8 and n=7 are set, it is possible to obtain a high output torque that is about eight times the torque generated when the planetary cylinder 6 revolves once. In this case, the minimum rotational displacement amount of the output shaft 2 is 360”/
(mXn), so the resolution of rotation control of the output shaft 2 does not deteriorate.

Moreover, according to the present embodiment, the solar cylinder 1. has the first electrodes 4a to 4h. In addition to the planetary cylinder 6 with the second electrodes 8a-8g, the output shaft 2. The main parts can be constructed by simply providing the bearing 3 and the universal joint 7, and the structure is extremely simple.

Furthermore, since the inertia of the planetary cylinder 6 functioning as a rotor can be reduced, it is possible to simultaneously improve the start/stop characteristics and suppress vibration and noise.

Of course, the first electrodes 4a to 4h and the second electrodes 8a to 8g
Since no electrostatic energy is consumed unless there is a leak in the capacitor comprised between The energy conversion efficiency when the cylinder 6 is rotated intermittently can be dramatically improved. Furthermore, in manufacturing the solar cylinder 1 and the planetary cylinder 6, lithography is used.

By applying semiconductor manufacturing technology such as thin film deposition, it is possible to create extremely fine and precise structures and integrate them, making it possible to achieve ultra-high performance that was not possible with conventional magnetic actuators. Miniaturization will become possible.

Incidentally, as shown in FIGS. 3 and 4 showing a second embodiment of the present invention, a larger number of first electrodes and a larger number of second electrodes may be provided. That is, in FIG. 3, 50 first electrodes 13 are arranged on the inner peripheral surface of the solar cylinder 12, which is the first cylindrical body.
are arranged at equal pitches, and 49 second electrodes 15 are arranged on the outer peripheral surface of the planetary cylinder 14 which is the second cylindrical body.
An example is shown in which the electrodes 13 are arranged at the same pitch,
In such a configuration, the output torque via the universal joint 16 and the output shaft 17 is approximately 50 times the torque generated when the planetary cylinder 14 revolves once, as can be understood from the above explanation. becomes. Furthermore, in this case, the degree of eccentricity between the rotation center S1 and the revolution center S2 of the planetary cylinder 14 becomes small, and the rotation of the planetary cylinder 14 becomes smooth. Note that in FIGS. 3 and 4, the illustration of the high dielectric constant insulating coating attached to the inner circumferential surface of the solar cylinder 12 is omitted.

Further, FIG. 5 shows a third embodiment of the present invention, and only the parts different from the first embodiment will be described below. That is, in this embodiment, a crank-shaped eccentric shaft portion 2a is integrally provided at the tip of the output shaft 2, and this eccentric shaft portion 2a is connected to the center portion of the bottom wall portion 6a of the planetary cylinder 6 via a bearing 18. It has a structure that supports it. In such a configuration, the number of rotations of the output shaft 2 becomes equal to the number of revolutions of the planetary cylinder 6, which is suitable for rotating the output shaft 2 at high speed.

FIG. 6 shows a fourth embodiment of the present invention, and hereinafter only the differences from the first embodiment will be explained. That is, in this embodiment, the first electrodes 4a to 4h on the solar cylinder 1 side are left as they are, and the second electrode 19 is attached to the outer peripheral surface of the planetary cylinder 6 over the entire circumferential direction. , the second electrode 19 is connected to a ground terminal. With this configuration as well, the planetary cylinder 6 is rotated in accordance with the switching operation of the changeover switches 10a to 10h in the switching circuit 9 in the same way as in the first embodiment, and the inner peripheral dimension of the solar cylinder 1 is set to Ls, Planetary cylinder 6
The outer circumferential dimension (actually the outer circumferential dimension of the second electrode 19) is L
When p, the rotation number of the planetary cylinder 6 is L of its revolution number.
s/(Ls-Lp) times. In particular, according to this embodiment, since the structure of the second electrode 19 is simplified, the planetary cylinder 6
The processing is simpler than in the first embodiment.

In the fourth embodiment, second electrodes 8a to 8g similar to those in the first embodiment are provided on the planetary cylinder 6 side, and a first electrode similar to the second electrode 19 is provided on the solar cylinder 1 side. It is also possible to have a configuration in which electrodes are provided.

7 and 8 show a fifth embodiment of the present invention, which focuses on the fact that increasing the effective surface area of the first electrode and the second electrode leads to higher output torque. Yes, this will be explained below. That is, in FIGS. 7 and 8, 20.degree. 21.22 is a solar cylinder which is a first cylindrical body, and these are integrally connected by a substrate 23 and are provided concentrically. 24, 25. 26 is a planetary cylinder which is a second cylindrical body that pairs with the solar cylinders 20, 21, and 22, and these are integrally connected by a substrate 27 and installed concentrically.

At this time, each planetary cylinder 24, 25.26 is formed to have a smaller diameter than the corresponding solar cylinder 20, 21.22, and is placed in each solar cylinder 20, 21.22 with the substrate 27 on the front side. has been done. Further, an output shaft 28 is supported through a bearing 29 in the central part of the substrate 23 on the side of the solar cylinders 20 to 22, and this output shaft 28 and the planetary cylinder 2
There is a universal joint 3o between the center part of the board 27 on the 4-26 side.
are connected via. And the solar cylinder 2°0.
For example, eight first electrodes 31, 32, 33 are arranged on the inner circumferential surface of each of the solar cylinders 20, 21° 22 at equal pitches, and the planetary cylinders 24° 25.26 For example, seven second electrodes 34, 35 .
36 are arranged at equal pitches for each planetary cylinder 24, 25, 26.

In this embodiment configured in this way, the first electrode 31.3
2.33 and each pair of second electrodes 34, 35.36,
A voltage is simultaneously applied to a predetermined pair of electrodes, and thereby an output torque approximately three times that of the first embodiment can be obtained.

In this fifth embodiment, the second electrode 34°35.3
6 are provided in the same manner as in the first embodiment, but these second electrodes 34, 35 . 36, a second electrode may be provided which is positioned over the entire outer peripheral surface of each planetary cylinder 24.degree. 25.26, as in the fourth embodiment.

Further, in each of the above embodiments, the solar cylinder is fixed and the rotational force of the planetary cylinder is extracted as an output, but the planetary cylinder may be fixed and the rotational force of the solar cylinder is extracted as an output. Furthermore, the first cylindrical body and the second cylindrical body are not necessarily limited to cylindrical shapes.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, and may be implemented with various modifications within the scope of the invention, for example, the switching circuit may be configured with semiconductor switching elements. can do.

[Effects of the Invention] As is clear from the above description, in the electrostatic actuator of claim 1, the overall size can be reduced, and high output torque can be achieved without reducing the resolution of output control. Of course, this makes it possible to apply it to applications where high torque is obtained at low speeds.

Further, according to the electrostatic actuator of the second aspect, in addition to the above-mentioned effects, the structure of the second electrode is simplified, so that it is possible to improve the manufacturability.

Furthermore, according to the electrostatic actuator of claim 3, the first
The effective total surface area of the electrode and the second electrode can be increased,
This makes it possible to further increase the output torque.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a first embodiment of the present invention, and FIG. 2 is a longitudinal sectional side view showing the first embodiment. 3 and 4 are views corresponding to FIGS. 1 and 2, respectively, showing a second embodiment of the present invention, and FIG. 5 is a view corresponding to FIG. 2, showing a third embodiment of the present invention. 6 is a view corresponding to FIG. 1 showing the fourth embodiment of the present invention, and FIGS. 7 and 8 are a longitudinal sectional front view and a view corresponding to FIG. 2 showing the fifth embodiment of the present invention, respectively. In the figure, 1, 12.20-22 are solar WJs (first cylindrical body), 2, 17.28 are output shafts, 4a-4h, 13,
31, 32.33 are the first electrodes, 6°14.24.25
．． 26 is a planetary cylinder (second cylindrical body), 7, 16.30
is a universal joint, 8a-8g. 15, 19, 34 and 35, 36 are second electrodes, 9 is a switching circuit, 10a to 10h are changeover switches, and 11 is a DC power source.

Claims (3)

[Claims] 1. a first cylindrical body; a second cylindrical body formed with a smaller diameter than the first cylindrical body and disposed within the first cylindrical body;
a plurality of first electrodes arranged on the inner circumferential surface of the first cylindrical body at a predetermined pitch in the circumferential direction; and a plurality of first electrodes arranged on the outer circumferential surface of the second cylindrical body at a predetermined pitch in the circumferential direction. By selectively charging between the plurality of second electrodes and the first and second electrodes to apply an electrostatic force between the two electrodes, the second cylindrical body is connected to the first cylindrical body. An electrostatic device comprising: a switching circuit for relatively planetary rotation along the inner circumferential surface of the cylindrical body; and configured to extract rotational force from one of the first and second cylindrical bodies. actuator. 2. a first cylindrical body; a second cylindrical body formed with a smaller diameter than the first cylindrical body and disposed within the first cylindrical body;
a plurality of node 1 electrodes arranged at a predetermined pitch in the circumferential direction on the inner circumferential surface of the first cylindrical body or the outer circumferential surface of the second cylindrical body; , selectively charging between a second electrode disposed on the outer peripheral surface or the inner peripheral surface of the first cylindrical body over the entire circumferential direction thereof, and the first and second electrodes. a switching circuit that planetarily rotates the second cylindrical body relative to the inner circumferential surface of the first cylindrical body by applying an electrostatic force between the electrodes,
An electrostatic actuator characterized in that it is configured to extract rotational force from one of the first and second cylindrical bodies. 3. A plurality of pairs of the first cylindrical body and the second cylindrical body are provided in a connected state for each cylindrical body, and each inner peripheral surface of the first cylindrical body and the second n-shaped body 3. The electrostatic actuator according to claim 1, wherein a first electrode and a second electrode are provided on each outer peripheral surface of the electrostatic actuator.